Joining Web Dissimilar Metals

User Manual: Joining-Dissimilar-Metals Welding

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Joining

Table of Contents

JOINING

Introduction . . . . . . . . . . . . . . . . . . .1

General Considerations . . . . . . . . . . .2

Safety . . . . . . . . . . . . . . . . . . . . . . . .2

Surface Preparation . . . . . . . . . . . . .3

Joint Design . . . . . . . . . . . . . . . . . . .3

Shielded Metal-Arc Welding . . . . . . .6

Gas Tungsten-Arc Welding . . . . . . . .7

Gas Metal-Arc Welding . . . . . . . . . . .8

Flux-Cored Arc Welding . . . . . . . . .11

Submerged-Arc Welding . . . . . . . . .12

Plasma-Arc Welding . . . . . . . . . . . .15

Overlaying . . . . . . . . . . . . . . . . . . . .16

Welding Nickel Alloy

Clad Steel Plate . . . . . . . . . . . . . . . .24

Welding Metallurgy

and Design . . . . . . . . . . . . . . . . . . .25

Welding Product Selection . . . . . . . .29

Corrosion Resistance . . . . . . . . . . . .29

Welding Precipitation –

Hardenable Alloys . . . . . . . . . . . . . .29

Fabricating Nickel-Alloy

Components for

High Temperature Service . . . . . . .32

Testing and Inspection . . . . . . . . . .33

BRAZING

Introduction . . . . . . . . . . . . . . . . . . .35

Silver Brazing . . . . . . . . . . . . . . . . .37

Copper Brazing . . . . . . . . . . . . . . . .39

Nickel Brazing . . . . . . . . . . . . . . . . .40

Other Brazing Alloys . . . . . . . . . . . .42

Inspection of Brazements . . . . . . . .43

SOLDERING

Introduction . . . . . . . . . . . . . . . . . . .44

Joint Design . . . . . . . . . . . . . . . . . .45

THERMAL

CUTTING

Introduction . . . . . . . . . . . . . . . . . . .46

Plasma-Arc Cutting . . . . . . . . . . . . .46

Powder Cutting . . . . . . . . . . . . . . . .47

Air Carbon-Arc Cutting . . . . . . . . . .47

Gas Tungsten-Arc Cutting . . . . . . .48

High-quality joints are readily produced in nickel

alloys by conventional welding processes. However,

some of the characteristics of nickel alloys necessi-

tate the use of somewhat different techniques than

those used for commonly encountered materials such

as carbon and stainless steels. This bulletin endeav-

ors to educate the reader in the processes and prod-

ucts used for joining the various high-performance

alloy products manufactured by Special Metals and

the basic information required to develop joining

procedures.

Special Metals Corporation (SMC) manufactures

companion welding products for the full range of its

wrought alloys and for many other materials. The

flux-covered electrodes, bare filler and flux-cored

wires, weldstrip and fluxes are designed to provide

strong, corrosion-resistant weld joints with the prop-

erties required to meet the rigors of the service for

which the fabricated component is designed. When

used with SMC alloys, they ensure single-source reli-

ability in welded fabrications. The SMC line of weld-

ing products also includes high-quality consumables

for welding iron castings and for joining dissimilar

metals. Descriptions and properties of all the weld-

ing products manufactured by Special Metals

Corporation and guidelines for welding product

selection are found in the brochure, “Special Metals

Welding Products Company: Welding Products

Summary” and on the websites, www.special met-

als.com and www.specialmetalswelding.com.

The scope of “Special Metals: Joining” is generally

limited to the joining of nickel alloys to themselves,

other nickel alloys, or steels. While the NI-ROD®line

of welding products are used for joining iron castings,

specific information on their use and the develop-

ment of procedures for joining cast iron are not

specifically addressed here. For detailed information

on welding iron castings with the nickel-base NI-

ROD welding products, the reader is directed to

“Special Metals Welding Products Company: NI-ROD

Welding Products”.

The choice of welding process is dependent upon

many factors. Base metal thickness, component

design, joint design, position in which the joint is to

be made, and the need for jigs or fixtures all must be

considered for a fabrication project. Service condi-

tions and corrosive environments to which the joint

will be exposed and any special shop or field-con-

struction conditions and capabilities which might be

required are also important. Also, a welding proce-

dure must specify appropriate welding products. The

information contained in “Special Metals: Joining”

should assist those tasked to develop procedures for

joining materials with SMC welding products with

identifying significant variables and determining

optimum joining processes, products, process vari-

ables, and procedure details. To discuss specific

applications and needs, the reader is encouraged to

contact sales, marketing, or technical service repre-

sentatives at any of the Special Metals Corporation

offices listed on the back cover.

Unless specifically noted otherwise, all procedures

described in this publication are intended for joining

alloy products that are in the annealed condition.

Values reported in the publication were derived

from extensive testing and experience and are typical

of the subject discussed, but they are not suitable for

specifications. Additional product information and

publications are available on the Special Metals web-

Joining

Introduction

sites, www.specialmetals.com and www.special-

metalswelding.com.

General Considerations

Most persons experienced in welding operations and

design have had experience with joining carbon,

alloy, and/or stainless steels. Thus, much of the

information in “Special Metals: Joining” is presented

as a comparison of the characteristics of nickel alloys

and steels and the processes and procedures used to

join them.

Welding procedures for nickel alloys are similar to

those used for stainless steel. The thermal expansion

characteristics of the alloys approximate those of car-

bon steel so essentially the same tendency for distor-

tion can be expected during welding.

All weld beads should have slightly convex con-

tours. Flat or concave beads such as those com-

monly encountered when joining stainless and car-

bon steels should be avoided.

Preheating nickel alloys prior to welding is not

normally required. However, if the base metal is cold

(35°F (2°C) or less), metal within about 12 in. (300

mm) of the weld location should be warmed to at

least 10° above the ambient temperature to prevent

the formation of condensate as moisture can cause

weld porosity. Preheat of the steel component may be

required when joining a nickel alloy to alloy or car-

bon steel. Preheat is often beneficial when joining

iron castings.

The properties of similar composition weldments

in nickel alloys are usually comparable to those of

the base metal in the annealed condition. Chemical

treatment (e.g., passivation) is not normally required

to maintain or restore corrosion resistance of a weld-

ed nickel alloy component. Most solid solution nick-

el alloys are serviceable as welded. Precipitation-

hardenable alloys welded with hardenable welding

products must be heat treated to develop full

strength. It may also be desirable to stress relieve or

anneal heavily stressed welded structures to be

exposed to environments which can induce stress cor-

rosion cracking.

In most corrosive media, the resistance of the weld

metal is similar to that of the base metal.

Overmatching or non-matching weld metals may

be required for some aggressive environments.

Safety

Like many industrial processes, there are potential

dangers associated with welding. Exposure of skin to

the high temperatures to which metals are heated

and molten weld metal can cause very serious burns.

Ultraviolet radiation generated by the welding arc,

spatter from the transfer of molten weld metal, and

chipped slag from SMA weldments cause serious eye

damage. Welding fumes can be harmful especially if

the welder is working in a confined area with limited

circulation. Thus, welders must be cognizant of the

dangers associated with their craft and exercise nec-

Figure 1. Sulfur embrittlement of root bend in Nickel 200

sheet. Left side of joint cleaned with solvent and clean cloth

before welding; right side cleaned with solvent and dirty cloth

exhibits cracking.

Figure 2. Typical effect of lead in MONEL alloy 400 welds.

Figure 3. Combined effects of sulfur and lead contamination.

Specimen removed from fatty-acid tank previously lined with

lead and not properly cleaned before installation of MONEL

alloy 400 lining.

essary precautions. Care must be taken and person-

al protection equipment must always be used.

The American Welding Society (AWS) has estab-

lished guidelines and standards for welding safety

and is an excellent source of information on the sub-

ject. AWS headquarters is at 550 LeJeune Road,

Miami, FL 33126-5671. Their telephone number is

(305) 443-9353. Those involved in welding opera-

tions are encouraged to visit their website,

www.aws.org.

Surface Preparation

Cleanliness is the single most important require-

ment for successfully welding nickel and nickel-

based alloys. At high temperatures, nickel and its

alloys are susceptible to embrittlement by sulfur,

phosphorus, lead, and some other low-melting point

substances. Such substances are often present in

materials used in normal manufacturing processes.

Examples are grease, oil, paint, cutting fluids,

marking crayons and inks, processing chemicals,

machine lubricants, and temperature-indicating

sticks, pellets, or lacquers. Since it is frequently

impractical to avoid the use of these materials during

processing and fabrication of the alloys, it is

mandatory that the metal be thoroughly cleaned

prior to any welding operation or other high-temper-

ature exposure.

The depth of attack will vary with the embrittling

element and its concentration, the alloy system

involved, and the heating time and temperature.

Damage under reducing conditions generally occurs

more quickly and is more severe than that taking

place in oxidizing environments. Figures 1, 2 and 3

show typical damage to welded joints that can result

from inadequate cleaning.

For a welded joint in material that will not be sub-

sequently reheated, a cleaned area extending 2 in.

(50 mm) from the joint on each side will normally be

sufficient. The cleaned area should include the edges

of the work piece and the interiors of hollow or tubu-

lar shapes.

The cleaning method depends on the composition

of the substance to be removed. Shop dirt, marking

crayons and ink, and materials having an oil or

grease base can be removed by vapor degreasing or

swabbing with suitable solvents. Paint and other

materials require the use of alkaline cleaners or spe-

cial proprietary compounds. If alkaline cleaners that

contain sodium sesquisilicate or sodium carbonate

are used, they must be removed prior to welding.

Wire brushing will not completely remove the

residue; spraying or scrubbing with hot water is the

best method. The manufacturer’s safety precautions

must be followed during the use of solvents and

cleaners.

A process chemical such as a caustic that has been

in contact with the material for an extended time

may be embedded and require grinding, abrasive

blasting, or swabbing with 10% (by volume)

hydrochloric acid solution followed by a thorough

water wash.

Defective welds can also be caused by the presence

of surface oxide on the material to be joined. This is

usually important in repair welding since new mate-

rial is normally supplied annealed and pickled clean.

The light oxide that results when clean material is

exposed to normal atmospheric temperatures will

not cause difficulty during welding unless the mate-

rial is very thin, below about 0.010 in. (0.254 mm).

However, the heavy oxide scale that forms during

exposure to high temperatures (hot-working, heat-

treating, or high-temperature service) must be

removed.

Oxides must be removed because they normally

melt at higher temperatures than the base metal. For

example, Nickel 200 melts at 2615 – 2635°F (1435 –

1446°C), whereas nickel oxide melts at 3794°F

(2090°C). During welding, the base metal may melt

and the oxide remain solid, causing lack-of-fusion

defects. The oxide should be removed from the joint

area before welding by grinding, abrasive blasting,

machining, or pickling.

Joint Design

Many different joint designs may be used when join-

ing nickel alloy products. Examples of some of the

joints commonly used are shown in Figure 4 (page 5).

Approximate amounts of weld metal needed with

these designs are given in Table 1 (page 4). The same

basic designs are used for all welding processes.

However, modification of the designs may be required

for submerged arc and gas metal arc welding to allow

adequate access to the joint. This is normally accom-

plished by either increasing the root gap or increas-

ing the included angle.

The most economical joint is usually that which

requires the minimum of preparation, requires the

least amount of welding consumables and welding

time while still resulting in the deposition of a satis-

factory weldment.

JOINT DESIGN

CONSIDERATIONS

The first consideration in designing joints for nickel

alloys is to provide proper accessibility. The joint

opening must be sufficient to permit the torch, elec-

trode, or filler metal to extend to the bottom of the

joint.

In addition to the basic requirement of accessibili-

ty, the characteristics of nickel-alloy weld metal

necessitate the use of joint designs that are differ-

ent than those commonly used for ferrous materi-

als. The most significant characteristic is the slug-

gish nature of the molten weld metal. Nickel alloy

weld metal does not flow or spread as readily as

steel weld metal. The operator must manipulate the

weld puddle so as to direct the weld metal to

the proper location in the joint. The joint must,

therefore, be sufficiently open to provide space for

movement of the torch or filler metal. The impor-

tance of producing slightly convex beads has been

Removeable Copper Backing

Reinforcement

.03-.06 in.

(0.76-1.5 mm)

stated previously and cannot be overemphasized. The

joint design chosen must allow for the first weld bead

to be deposited with a convex surface.

Small included angles and narrow roots induce con-

cave beads and often lead to centerline cracking.

Another different characteristic is the lower weld

penetration encountered when welding nickel

alloys. This is caused by the physical properties of

nickel alloys and must be considered in the weld

design. The lower penetration makes necessary

the use of smaller lands in the root of the joint.

Increases in weld current will not significantly

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Removeable Copper Backing

Reinforcement

.03-.06 in.

(0.76-1.5 mm)

Removeable Copper Backing

Reinforcement

.04-.08 in.

(1.0-2.0 mm)

No Backing Used. Under Side

of Weld Chipped and Welded.

Reinforcement

.04-.08 in.

(1.0-2.0 mm)

LAP

(a) To find linear feet of weld per pound of electrode, take reciprocal of pounds per linear foot. If underside of first

bead is chipped out, and welded, add 0.21 lb of metal deposited (equivalent to 0.29 lb of electrode).

increase the penetration of the arc. Excessive weld

current when shielded metal arc welding can cause

overheating of covered electrodes such that the

flux spalls off and the deoxidizers in the flux are

destroyed. The use of excessive heat with gas

shielded processes results in weld spatter and

overheating of the welding equipment. With proper

joint selection and design, the welding product can

be effectively used within the recommended

current ranges and a sound, full penetration

weld deposited.

GROOVE JOINTS

Beveling is not normally required for material 3/32

in. (2.36 mm) or less in thickness.

Material thicker than 3/32 in. (2.4 mm) should be

beveled to form a V-. U-, or J- groove, or it should be

welded from both sides. Otherwise, erratic penetra-

tion will result, leading to crevices and voids that will

be potential areas of accelerated corrosion in the

underside of the joint. It is generally that surface

which must withstand corrosion. Notches resulting

from erratic penetration can also act as mechanical

stress risers and propagate to form cracks.

Deposition of the root pass by gas tungsten-arc

welding results in the best underbead contour on

joints that cannot be welded from both sides. A com-

mon example is the root pass of butt welds in pipes

1/16"

(1.6 mm)

1/16"

(1.6 mm)

V-Groove

Double

V-Groove

U-Groove

Double

U-Groove

J-Groove

80˚

15˚

3/16" - 5/16"

(4.8 - 7.9 mm)

3/32"

(2.4 mm)

3/32"

(2.4 mm)

3/8"

(9.5 mm)

1/8"

(3.2 mm)

15˚

50˚

15˚

3/16" - 5/16"

(4.8 - 7.9 mm)

.015" - .035"

(0.381 - 0.889 mm)

3/16" - 1/4"

(4.8 - 6.4 mm)

1/8"

(3.2 mm)

Drilled for Root Gas Purge

Standard Design

3/16" - 1/4"

(4.8 - 6.4 mm)

Figure 5. Groove designs for backup bars.

Figure 4. Typical joint designs.

and tubes.

For material over 3/8 in. (9.5 mm) thick, a double

U-or double V-joint design is preferred. The increased

cost of joint preparation is usually offset by savings

in welding products and welding time. The double

joint design also results in less residual stress than

will be developed with a single-groove design.

As shown in Figure 4, V-groove joints are normal-

ly beveled to an 80-degree included angle, and U-

groove joints to a 15-degree side angle and a 3/16 in.

to 5/16 in. (4.8-7.9 mm) bottom radius. Single beveled

for T-joints between dissimilar thicknesses of materi-

al should have an angle of 45 degrees. The bottom

radius of a J-groove in a T-joint should be 3/8 in.

(9.5 mm) minimum.

CORNER AND LAP JOINTS

Corner and lap joints may be used where high serv-

ice stresses will not be developed. It is especially

important to avoid their use at high temperatures

or under thermal or mechanical cycling conditions.

Butt joints (in which stresses act axially) are pre-

ferred to corner and lap joints (in which stresses tend

to be eccentric). When corner joints are used, a full-

thickness weld must be made. In most cases, a fillet

weld on the root side will be required.

JIGS AND FIXTURES

When fabricating thin sections (e.g., sheet and strip),

jigs, clamps, and fixtures can reduce the cost of weld-

ing and promote consistent, high-quality welds.

Proper jigging and clamping will facilitate welding

by holding the material firmly in place, minimizing

buckling, maintaining alignment, and when needed,

providing compressive stress in the weld.

Steel and cast iron may be used for all parts

of gas-welding fixtures. For arc welding processes,

any portion of the fixture which might potentially

come in direct contact with the arc should be made

of copper.

Backup or chill bars should be provided with a

groove of the proper contour to permit penetration of

weld metal and to avoid the possibility of gas or flux

being trapped at the bottom of the weld. The width of

the groove and the spacing of hold-down bars should

be adjusted to obtain a proper balance of restraint,

heat transfer, and heat input.

Grooves in backup bars for arc welding should be

shallow. They are usually 0.015 to 0.035 in. (0.381-

0.889 mm) deep and 3/16 to 1/4 in. (4.8 to 6.4 mm)

wide. The grooves are normally rounded; drilled

grooves are generally used in conjunction with back-

up gas. Both types are shown in Figure 5.

Nickel alloy parts require about the same amount

of clamping or restraint as mild steel. The hold-down

bars should be located sufficiently close to the weld to

maintain alignment and the proper degree of heat

transfer. Except as described below, the hold-down

pressure should be sufficient to maintain alignment

of the parts.

The restraint provided by a properly constructed

fixture can be utilized to particular advantage when

the gas tungsten-arc process is used to weld thin

material. If the groove is appropriately contoured

and if a high level of hold-down force is used with the

hold-down bars placed near the line of welding, the

expansive force created in the exposed welding area

will result in compressive force in the weld. The com-

pression will have an upsetting effect on the hot weld

metal, and welds having a slight top and bottom rein-

forcement can be produced without filler metal.

Shielded Metal-Arc Welding

In general, shielded metal-arc welding is used for

material about 1/16 in. (1.6 mm) and over in thick-

ness. Thinner material, however, can be welded by

the process if appropriate jigs and fixtures are used.

ELECTRODES

For most welding applications, the composition of the

deposit of the welding electrode resembles that of the

base metal with which it is used. The weld metal

composition is sometimes adjusted by the manufac-

turer to better satisfy weld requirements.

Prior to their use, flux covered electrodes should

remain sealed in their moisture-proof containers in

a dry storage area. All opened containers of elec-

trodes should be stored in a cabinet equipped with a

desiccant or heated to 10-15°F (6-8°C) above the

highest expected ambient temperature. The flux

coating is hygroscopic and will absorb excessive

moisture if exposed to normal humidity.

Electrodes that have absorbed excessive moisture

can be reclaimed by heating to drive off the absorbed

moisture. They may be baked at 600°F (316°C) for

1 hr or 500° (260°C) for 2 hrs. Heating should be in a

vented oven. The electrodes must be removed from

the containers during baking.

CURRENT

Each electrode diameter has an optimum range of

operating current. When operated within the pre-

scribed current range, the electrodes have good arc-

ing characteristics and burn with a minimum of

spatter. When used outside that range, however,

the arc becomes unstable and the products tend to

overheat before the entire electrode is consumed.

Excessive current can also lead to porosity, compro-

mised properties and bend test failures because

alloying elements and deoxidizers are destroyed

(oxidized) before they can be melted into the weld

puddle.

The current density required for a given joint is

influenced by such variables as material thickness,

welding position, type of backing, tightness of clamp-

ing, and joint design. Slight reductions in current

(5 to 15A) are necessary for overhead welding.

Vertical welding requires 10 to 20% less current than

welding in the flat position. Actual operating current

levels should be developed by trial welding on scrap

material of the same thickness having the specified

joint design. Recommended operating ranges for cur-

rent are printed on the product label affixed to each

electrode container.

WELDING PROCEDURE

Nickel and nickel-alloy weld metals do not flow and

spread like steel weld metal. The operator

must direct the flow of the puddle so the weld metal

wets the joint sidewalls and the joint is filled appro-

priately. This is sometimes accomplished by

weaving the electrode slightly. The amount of

weave will depend on such factors as joint design,

welding position, and type of electrodes. A straight

drag (stringer) bead deposited without weaving may

be used for single-bead work, or in close quarters on

thick sections such as in the bottom of a deep groove.

However, a weave bead is generally desirable. When

the weave progression is used, it should not be wider

than three times the electrode core diameter.

Regardless of whether the welder uses weaving or

the straight stringer technique, all weld beads should

be deposited such that they exhibit the recommend-

ed slightly convex surface contour.

When used properly, SMC flux covered welding

electrodes should exhibit a smooth arc and no pro-

nounced spatter. When excessive spatter occurs, it is

generally an indication that the arc is too long,

amperage is too high, polarity is not reversed, or that

the electrode has absorbed moisture. Excessive spat-

ter can also be caused by magnetic arc below.

When the welder is ready to break the arc, it

should first be shortened slightly and the travel

speed increased to reduce the puddle size. This prac-

tice reduces the possibility of crater cracking and oxi-

dation, eliminates the rolled leading edge of the

crater, and prepares the way for the restrike.

The manner in which the restrike is made will

significantly influence the soundness of the weld. A

reverse or “T” restrike is recommended. The arc

should be struck at the leading edge of the crater and

carried back to the extreme rear of the crater at a

normal drag-bead speed. The direction is then

reversed, weaving started, and the weld continued.

This restrike method has several advantages. It

establishes the correct arc length away from the

unwelded joint so any porosity resulting from the

strike will not be introduced into the weld. The first

drops of quenched or rapidly cooled weld metal are

deposited where they will be remelted, thus,

minimizing porosity.

Another commonly used restrike technique is to

strike the arc on the existing bead In this manner,

the weld metal likely to be porous can be readily

removed by grinding. The restrike is made 1/2 to 1 in.

(13 to 25 mm) behind the crater on top of the previ-

ous pass, and the restrike area is later ground

level with the rest of the bead. This technique is

often used for applications requiring that welds

meet stringent radiographic inspection standards.

It is also noteworthy that it is much easier for

welders with lesser levels of skill to produce high

quality welds than they can using the “T” restrike

technique.

CLEANING

The slag on shielded metal-arc welds is quite brittle.

It is best removed by first chipping with a hammer

and chisel or a welder’s chipping hammer. It should

then be brushed clean with a stainless steel wire

brush that has not been contaminated with other

metals or deleterious compounds. Brushing may be

manual or by using powered brushes.

Complete slag removal from all welds is recom-

mended. When depositing a multiple pass weldment,

it is essential that all slag be removed from a

bead before the subsequent one is deposited.

Removal is mandatory for applications requiring

resistance to aqueous corrosion. Weld slag can act

as a crevice and induce localized corrosion in aqueous

environments. Also, the slag contains halides

which can greatly increase the corrosivity of aqueous

media. At high temperatures the slag can become

molten and reduce the protective oxide layer on

the surface of nickel-base alloys, thus accelerat-

ing corrosion (oxidation, sulfidation, carburization,

etc.).

Gas Tungsten-Arc Welding

Gas tungsten-arc welding is widely used for nickel

alloys. It is especially useful for joining thin sections

and when flux residues are undesirable. The GTAW

process is also the primary joining method for pre-

cipitation-hardenable alloys. GTAW is performed

with direct current and straight polarity (DCEN).

GASES

Recommended shielding gases are helium, argon, or

a mixture of the two. Additions of oxygen, carbon

dioxide or nitrogen can cause porosity in the weld

or erosion of the electrode and should be avoided.

Small quantities (up to 5%) of hydrogen can be added

to argon for single-pass welding. The hydrogen

addition produces a hotter arc and more uniform

bead surfaces. The use of hydrogen is normally

limited to automatic welding such as the production

of tubing from strip.

For welding thin material without the addition of

filler metal, helium has shown the advantages over

argon of reduced porosity and increased welding

speed. Welding travel speeds can be increased as

much as 40% over those achieved with argon. The

arc voltage for a given arc length is about 40%

greater with helium. Consequently, the heat input

is greater. Since welding speed is a function of heat

input, the hotter arc permits higher speeds.

The arc is more difficult to start and maintain in

helium when the welding current is below about 60

amps. When low currents are required for joining

small parts or thin material, either argon shielding

gas should be used or a high-frequency current

arc-starting system should be added.

Shielding gas flow rate is critical. Low rates will

not protect the weld while high rates can cause

turbulence and aspirate air, thus, destroying the

gas shield. For argon, 10 to 20 cu.ft./hr (0.28 to 0.57

cu.m./hr) is typical for manual welding. Machine

welding may require considerably higher rates.

Helium should flow at 1-1/2 to 3 times the rates for

argon to compensate for helium’s greater buoyancy.

The largest gas cup practical for the job should be

used. The cup should be maintained at the minimum

practical distance from the work.

Welding grades of argon and helium are produced

to a very high degree of purity of the gases. Even a

small amount of air will contaminate the protective

gas shield and cause porosity in the weld. Shielding

gas flow can be disrupted by drafts, wind, fans, and

the cooling systems of electric equipment. Air move-

ment from such sources should be avoided. A gas lens

should be used on the torch to stabilize the gas col-

umn and provide more efficient shielding.

Contamination can also result from air picked up in

the gas stream as it leaves the torch or from ineffi-

cient distribution of the gas shield around the elec-

trode and joint. The gas protection afforded an edge

weld is not as good as that for a flat butt joint.

Proper maintenance of equipment is essential. If

the electrode extension cap or the gas cup is loose, a

Venturi effect can be created that will draw air into

the gas stream. The O-rings in water-cooled equip-

ment should be checked periodically. Even a small

leakage of air or water into the shielding can provide

sufficient contamination to cause porosity and weld

oxidation and discoloration.

ELECTRODES

Tungsten electrodes or those alloyed with thorium

may be used. A 2% thoria electrode will give good

results for most welding applications. Although the

initial cost of the alloyed electrodes is greater, their

longer life, resulting from lower vaporization and

cooler operation in conjunction with greater current-

carrying capacity make them more economical in the

long term. Regardless of the electrode used, it is

important to avoid overheating them at excessive

current levels.

The shape of the electrode tip can have a signifi-

cant effect on the depth of penetration and the

width of the bead, especially with welding current

over 100 amps. The best arc stability and penetration

control are achieved with a tapered tip. For most

work, the vertex angle should be between 30 and 120

degrees with a flat land of about 0.015 in (0.38 mm)

diameter on the tip end. Larger angles (blunter tips)

can be used to produce narrower beads and deeper

penetration.

The tungsten electrode will become contaminated

if it contacts the weld metal or the base metal surface

during the welding operation. If this occurs, the elec-

trode should be cleaned and reshaped by grinding.

Chemical compounds that chemically react with the

electrode to point it are also available.

CURRENT

Direct current, straight polarity (electrode negative)

is recommended for both manual and automated

welding. A high-frequency circuit for assistance in

starting the arc and a current-decay unit for slowly

stopping the arc should also be used when GTA weld-

ing nickel base alloys. Contact starts and “pull away”

arc stops are unacceptable techniques.

A high-frequency circuit eliminates the need to

contact the work with the electrode to start the arc.

Contact starting can damage the electrode tip and

also result in tungsten inclusions in the weld metal.

Another advantage of a high-frequency circuit is that

the starting point can be chosen before the welding

current starts, eliminating the possibility of arc

marks on the base material.

Rough, porous, or fissured craters can result from

an abrupt arc break. A current-decay unit gradually

lowers the current before the arc is broken to reduce

the puddle size and end the bead smoothly. Units

with stepless control are preferred over those using

step reduction.

FILLER METALS

Welding products for the gas-tungsten arc process

are normally similar in chemical composition to the

base metals with which they are used. Because of

high arc currents and high puddle temperatures, the

filler metals often contain small additions of alloying

elements to deoxidize the weldment to prevent solid-

ification and hot cracking.

WELDING PROCEDURE

The torch should be held at nearly 90 degrees to

the work. A slight inclination in the forehand posi-

tion is necessary for good visibility during manual

welding. However, too acute an angle can cause aspi-

ration of air into the shielding gas.

The electrode extension beyond the gas cup should

be as short as possible. However, it must be appro-

priate for the particular joint design. For example, an

extension of 3/16 in. (4.8 mm) maximum is used for

butt joints in thin material, whereas 3/8 to to 1/2 in.

(9.5 to 13 mm) may be required for some fillet

welds.

To ensure a sound weld, the arc length must be

maintained as short as possible. When no filler

metal is added, the arc length should be 0.05 in. (1.27

mm) maximum and preferably 0.02 to 0.03 in (0.51 to

0.76 mm). Excessive arc length during autogenous

GTAW can cause porosity as shown in Figure 6.

The arc length may be longer if filler metal is to be

added but it should be the minimum length practical

for the diameter of filler metal to be used.

The size of filler metal used must be appropriate

for the thickness of the material being welded. The

filler metal should be added carefully at the leading

edge of the puddle to avoid contact with the elec-

trode. The hot end of the filler metal should always

be kept in the protective atmosphere. Agitation of the

puddle should be avoided. The molten pool must be

kept as quiet as possible to prevent burning out of

the deoxidizing elements.

Filler metals contain elements which impart

resistance to cracking and porosity to the weld metal.

For optimum benefit from these elements, the com-

pleted weld should consist of at least 50% and prefer-

ably 75% filler metal.

Welding speed has a significant effect on the

soundness of the weld, especially when no filler

metal is added. For a given thickness of material,

there is an optimum speed range for minimum poros-

ity. Travel speeds outside that range can result in

porosity.

Shielding of the weld root is usually required with

gas-tungsten-arc welding. If a full penetration weld

is made without root protection, the underside of the

weld bead will likely be discolored (oxidized) and

porous. Shielding can be provided by grooved back-

up bars or inert-gas backing.

Gas Metal-Arc Welding

Gas metal-arc welding is a popular process because

of its high deposition rate and welder appeal. Most

nickel alloys may be GMA welded using the spray,

Figure 6. Effect of arc length on soundness of welds in

MONEL alloy 400. Top weld made with correct 0.050 in. (1.27 mm),

arc length. Bottom weld made excessive, 0.150 in. (3.81 mm), arc

length.

short-circuiting, and pulsing modes of transfer with

excellent results. Welding in the globular transfer

mode is not recommended as the erratic arc often

results in inconsistent penetration and uneven bead

contour.

Guidelines for selection of mode of transfer are

much the same for nickel alloys as those for ferrous

materials. Some power sources are capable of multi-

ple mode use while others may only be used in a

single mode. Power sources for welding nickel alloys

in the short-circuiting mode of transfer must

have good slope control. The current generation of

power sources for GMAW in the pulsing transfer

offer excellent solid state controls and very pleasing

welding characteristics. Their arc wave control

.035 475-520 26-32 175-260

.045 250-300 26-32 225-300

.062 150-200 27-33 250-330

.035 475-575 26-32 200-300

.045 250-320 26-32 225-325

.062 175-220 27-33 275-350

.035 425-520 26-32 200-300

.045 275-320 26-32 250-325

.062 175-220 27-33 275-350

.035 425-520 26-32 175-240

.045 250-310 26-32 225-300

.062 175-220 27-33 250-330

.030 550-700 26-32 175-240

.035 450-520 26-32 175-240

.045 250-310 26-32 225-300

.062 125-200 27-33 250-330

.035 425-520 26-32 175-240

.045 250-320 26-32 225-300

.062 125-200 27-33 250-330

.045 300-400 29-33 200-270

.062 175-250 29-33 250-330

.030 550-700 26-32 175-240

.035 450-600 26-32 180-245

.045 250-350 26-32 225-300

.062 125-225 27-33 250-345

FFiilllleerr MMeettaall

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WWiirree

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((iinn))((iinn//mmiinn))((vvoollttss))((aammppss))GGaass

MONEL Filler Metal 60

MONEL Filler Metal 67

Nickel Filler Metal 61

INCONEL Filler Metal 62

INCOLOY Filler Metal 65

INCONEL Filler Metal 82

INCONEL Filler Metal 52

INCONEL Filler Metal 92

NILO Filler Metal CF36

NILO Filler Metal CF42

INCONEL Filler Metal C-276

INCONEL Filler Metal 617

INCONEL Filler Metal 622

INCONEL Filler Metal 625

INCONEL Filler Metal 686CPT

Argon

Argon or

A/25-He

Argon or

Ar/25-He

Argon or

Ar/25-He

Argon

Argon or

Ar/25-He

(a) Gas flow of 35 - 60 ft3/h (CFH), Polarity Direct Current Electrode Positive (DCEP).

makes them particularly useful for out-of-position

welding.

Short-circuiting transfer is normally used for join-

ing thin sections of material (up to about 1/8-in (3.2-

mm) thick). Short-circuiting transfer takes place at

low heat input and gives good results in joining

material such as thin sections that could be distorted

by excessive heat. Short-circuiting transfer is nor-

mally limited to single pass welding. When used for

multiple pass welds, it often results in lack of fusion

and penetration defects.

GMAW in the spray transfer mode is a very effec-

tive means of welding heavy sections of material.

Spray transfer takes place at high heat input which

results in a stable arc and high deposition rates.

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.035 (0.9)

.045 (1.2)

WWiirreeWWiirreeFFlloowwAAvveerraaggeePPeeaakkSSttaarrttTTiimmee @@BBaacckkggrroouunndd

DDiiaammeetteerrFFeeeeddGGaassRRaatteeVVoollttaaggeeCCuurrrreennttFFrreeqquueennccyyCCuurrrreennttCCuurrrreennttPPeeaakkCCuurrrreenntt

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300-500

250-450

75Ar/25 He

65Ar/35 He

75Ar/25 He

65Ar/35 He

35-50

22-29

24-30

90-140

120-170

50-110

60-120

250-400

300-450

300

1.5-3.5

1.8-4.0

40-80

40-120

Spray transfer is generally limited to flat-position

welding. GMAW in the spray transfer mode is a very

severe process with respect to its effect on the metals

being welded. Some alloys are not capable of being

welded by this process due to problems with solidifi-

cation and hot cracking. Settings for spray transfer

are found in Table 2.

When GMA welding in the pulsing mode of trans-

fer, the current actually pulses generally along a

square wave pattern. At the peak current transfer is

in the spray mode. The background current is much

lower so transfer is in the globular range. The cur-

rent normally pulses 60 or 120 cycles per sec-

ond. However, some machines allow the operator to

adjust the pulse frequency. The result of the high

pulse rates is that the arc action resembles spray

transfer but the puddle is cold enough so the process

can be used out-of-position. The high peak current

eliminates the erratic arc and limited penetration

problems associated with conventional globular

transfer. Settings for pulsing transfer are found in

Table 3.

SHIELDING GASES

The protective atmosphere for gas metal-arc welding

is dependent upon the metals being joined and the

welding procedure. The optimum shielding gas will

vary with the type of metal transfer used. Argon or

argon mixed with helium are used for most nickel

alloy GMA welding applications. Carbon dioxide

(CO2) or a mixture of argon and CO2are often used

when welding iron castings with NI-ROD filler met-

als.

Welding torches that are rated for use with inert

gases (argon and helium) should be selected for use

with nickel alloy filler metals. They are shielded

with inert gas with an air-cooled torch. Occasionally

wire feed problems are reported. These problems are

usually traced to torch overheating. This is because

air-cooled torches are normally rated for use with

CO2shielding gas. CO2provides significantly more

cooling than inert gases. When inert gas shielding is

used, the torch rating is reduced by approximately

half of the standard duty cycle rating with CO2.

GASES FOR

SHORT-CIRCUITING TRANSFER

Argon with an addition of helium usually gives the

best results with short-circuiting transfer. Argon

alone provides a pronounced pinch effect, but it may

also produce excessively convex beads which leads to

cold lapping (lack of fusion). The wetting action pro-

vided by helium results in flatter beads, and the ten-

dency for cold lapping is reduced.

Gas flow rates for short-circuiting transfer range

from 25 to 45 ft3/h (0.71 to 1.3 m3/h). As the percent-

age of helium is increased, the flow rate must be

increased to maintain adequate protection.

The size of the gas cup can have important effects

on welding conditions. For example, with 50:50

argon-helium at a flow rate of 40 ft3/h (1.1 m3/h), a

3/8-in (9.5-mm) diameter cup limits wire feed to

250 in/min (6.4 m/min) and current to about 120 A.

With a 5/8-in (16-mm) diameter cup, however, wire

feed can be increased to over 400 in/min (10.2 m/min)

and current 160-180 A without oxidation of the weld

bead.

GASES FOR

PULSING TRANSFER

Argon with an addition of helium is recommended

as the atmosphere for pulsing-arc transfer. Good

results have been obtained with helium contents

of 15-20%. The flow rate should be at least

25 ft3/min (0.7 m3/h) and 45 ft3/min (1.3 m3/h)

maximum. Excessive rates can interfere with the arc.

For some specialized applications, pure helium

and higher helium mixes have been used with the

pulsed-GMAW process. As the percentage of

helium increases, there is greater tendency for arc

instability. However, for this low heat input process,

helium greatly enhances wetting.

GASES FOR

SPRAY AND GLOBULAR TRANSFER

With spray and globular transfer, good results have

been obtained with pure argon. The addition of oxy-

gen or carbon dioxide to argon will result in heavily

oxidized and irregular bead surfaces. Oxygen and

carbon dioxide additions can cause severe porosity in

pure nickel and MONEL alloy welds. Pure helium

has also been used. However, its use results in an

unsteady arc and excessive spatter.

Gas flow rates range from 25 to 100 ft3/h (0.71 to

2.83 m3/h), depending on joint design, welding posi-

tion, gas-cup size, and whether a trailing shield

is used.

FILLER METALS

The proper wire diameter depends on the type of

metal transfer and the thickness of the base materi-

al. In general, 0.062 in (1.1 mm) diameter wire is

used with spray transfer, 0.035 in (0.9 mm) and 0.045

in (1.1 mm) with pulsing-arc transfer, and 0.035 in.

(0.9 mm) with short-circuiting transfer.

CURRENT

Reverse-polarity direct current (DCEP) should be

used for gas metal-arc welding with all methods of

metal transfer.

Spray transfer requires current in excess of

the transition point, the value at which transfer

changes from the globular to the spray mode. The

transition point is affected by variables such as

wire diameter, wire composition, and power source

characteristics.

Constant-voltage power sources are recommended

for all gas metal-arc welding. For short-circuiting

transfer, the equipment must have separate slope

and secondary inductance controls. Power sources for

welding in the pulsing transfer vary greatly in

design, operation, and control systems. It is suggest-

ed that the user contact the manufacturer for specif-

ic operating instructions.

WELDING PROCEDURE

Best results are obtained with the welding gun posi-

tioned at about 90 degrees to the joint. Some slight

inclination is permissible to allow for visibility for

manual welding. However, excessive displacement

can result in aspiration of the surrounding atmos-

phere into the shielding gas. Such contamination will

cause porous or heavily oxidized welds.

Optimum welding conditions vary with method of

metal transfer. The arc should be maintained at a

length that will not cause spatter. Too short an arc

will cause spatter, but an excessively long arc is diffi-

cult to control. The wire feed should be adjusted in

combination with the current to give the proper arc

length.

Lack of fusion can occur with the short-circuiting

method if proper manipulation is not used. The gun

should be advanced at a rate that will keep the arc in

contact with the base metal and not the puddle. In

multiple pass welding, highly convex beads can

increase the tendency toward cold lapping. With

pulsing transfer, manipulation is similar to that used

for shielded metal-arc welding. A slight pause at the

limit of the weaves is required to avoid undercut.

The filler wire and guide tube must be kept clean.

Dust or dirt carried into the guide tube can cause

erratic feed and wire jams (“bird nests”). The tube

must be blown out periodically, and the spool of wire

must be covered when not in use to avoid dirt

buildup.

Flux-Cored Arc Welding (FCAW)

The flux-cored arc welding (FCAW) process is becom-

ing more widely accepted for nickel alloys. The fea-

ture that best distinguishes this process from other

semi-automatic arc welding processes is the flux in

the core of the filler metal. The process can be either

self-shielded or gas-shielded depending on the com-

position of the flux. The type of flux also determines

whether or not the process can be used in the down-

hand position or out of position. The flux also pro-

vides for better protection of the weld surface against

oxidation, and provides uniform and superior wetting

characteristics which may, at times, be marginal for a

bare wire that is shielded only by inert gases. This

assists in producing a slightly convex bead shape or

profile.

WELDING EQUIPMENT

The equipment for welding with flux-cored wire is

usually the same as that used for GMAW or SAW.

Direct-current power sources with constant

potential and reverse polarity generally give the

best results. Wire feed rolls should be knurled

and have grooves of either “U” or “V” shape. Smooth

rolls can slip or flatten the wire. The wire must feed

evenly through the gun. Four-roll feeders generally

feed wire more reliably than those with two

rolls. Contact tips should be the same diameter as

the wire used.

GAS

Most FCAW wires are used with additional gas cov-

erage. A wide range of gases are used, including

argon, carbon dioxide, or a combination of the two.

The shielding gas protects the arc and molten metal

from the oxygen and nitrogen in air. The slag

ingredients shape the weld bead, stabilize the arc,

deoxidize the molten weld puddle, and form the

protective slag covering. When additional shield-

ing gas is used, a gas flow rate of 25 to 50 ft3/h

(.7 to 1.4 m3/h) is recommended. Like other welding

processes, the FCAW process generates fumes.

Smoke extracting equipment or ventilation systems

improve operator comfort and are essential for oper-

ator safety.

Self-shielding FCAW electrodes contain flux ingre-

dients which vaporize and displace the air protecting

the weld from gas contaminants. The self-shielding

process lends itself to use in field welding applica-

tions. Generally, longer electrode extensions are used

with self-shielding electrodes, while shorter electrode

extensions are used with additional shielding gases.

FLUX

The flux ingredients have a dramatic effect on the

welding operability of the product. Fluxes can be

designed for down-hand or out of position welding.

For down-hand or flat welding, the nature of the

molten flux allows for ease of arc control, superior

flow of weld metal, and penetration.

All position FCAW products utilize flux systems

from which the molten slag freezes more quickly,

thus, holding the weld metal in place. They general-

ly form a smaller puddle. Even though, in most cases,

the product will perform satisfactory in the down-

hand position, the operability characteristics are

optimum when used out-of-position. FCAW products

specifically designed for flat position welding will

give better results.

The fused flux should be removed from the

deposited weld bead before proceeding with the next

bead. Welds should be completely free of all slag

Note: Above referenced parameters are for INCO-CORED 82 DH & 82 AP,

NI-ROD FC55, INCO-CORED 625 DH & 625 AP, FCAW consumables

where “DH” denotes (1G) or Down Hand Position and “AP” denotes

(1G through 6G) or all positions.

*INCO-CORED 82 AP and 625 AP only.

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ffoorr FFlluuxx--CCoorreedd WWiirree

WWeellddiinnggEElleeccttrrooddee

WWiirreeWWiirree ffeeeeddccuurrrreenntt WWeellddiinnggeexxtteennssiioonn

ddiiaammeetteerrssppeeeedd((DDCCRRPP))vvoollttaaggee((ssttiicckk oouutt))

iinn ((mmmm))iinn//mmiinn ((mm//mmiinn))aammppss vvoollttssiinn ((mmmm))

0.093 (2.4) 100-200 (2.5-5) 250-350 28-33 0.75-1 (19-25)

0.078 (2.0) 150-250 (3.75-6.3) 225-325 28-32 5/8-7/8(16-22)

0.062 (1.6) 200-300 (5-7.5) 200-300 27-32 1/2-3/4 (12.5-19)

0.045 (1.1) 250-350 (6.3-9) 130-180 26-30 3/8-5/8 (9.5-16)

0.045 (1.1)* 275-350 (7-9) 150-210 26-31 0.5-1 (12.5-25)

before entering service for the same reasons dis-

cussed under SMAW. Prior to use, the wire should be

stored so it does not absorb moisture. Wire which is

not being used should be stored in a cabinet equipped

with a desiccant or heated to 10°-15°F (6°- 8°C)

above the highest expected ambient temperature.

Flux-cored wires which have absorbed moisture may

be re-baked at 400°F (204°C) for 6 hours.

WELDING PARAMETERS

The current setting can significantly affect the weld-

ing deposition rate and finished weld characteristics.

The average welding current (direct current, reverse

polarity) for 0.045 in. (1.1 mm) diameter wire is

approximately 170 amps. An increase in welding cur-

rent will increase penetration and dilution, and a

decrease in welding current may improve out-of-posi-

tion welding operability and lower dilution.

Excessive current can cause a lack of slag coverage

and excessive spatter, and increase cracking suscep-

tibility.

Arc length increases with increasing voltage. High

voltage levels increase the possibility of contamina-

tion from the atmosphere and, thus, the likelihood of

porosity. Bead width and weld spatter also will

increase with higher voltage levels. Since a short

arc length should be maintained with all nickel

alloys, the average welding voltage should be approx-

imately 28 volts.

The amount of electrode extension (“stickout”)

also affects spatter and penetration. With longer

extension, more of the available power is used to

heat the wire, leaving less power to penetrate the

workpiece. In addition, the overheating of the wire

could cause excessive spatter. Shorter extensions

may be necessary for better penetration and reducing

spatter, but should generally be 3/8 - 5/8 in. (9.5 - 16.0

mm). After electrode extension is established for a

particular application, it should be closely main-

tained for consistent results.

Welding travel speed has a major effect on heat

input, penetration and dilution. At a given current

level, faster travel speeds reduce heat input but

increase penetration and dilution. Slower travel

speeds increase the amount of weld metal deposited

in a given length of bead, providing a molten metal

“cushion” which decreases penetration, dilution and

undercutting tendencies. Flux-cored wires may be

deposited with a slight “drag” or a “push”, but gener-

ally perform better with the torch angle perpendicu-

lar to the work. Stringer or weave techniques can be

employed depending upon the application and joint

design.

WELDING PROCEDURE

High quality, crack-resistant welds are readily

attainable with proper welding procedure. In gener-

al, even though the nature of the flux allows for some

cleaning of surface impurities and oxides, joint

preparation and base metal cleanliness are just as

important as when welding with solid nickel alloy

wires. The condition of the base metal greatly

affects the quality of the welded joints. As with all

nickel alloys, all surfaces to be welded should be rel-

atively free from oxides (especially scale from base

metal heat treatments) and impurities. A light sand-

ing or grinding is recommended, followed by a sol-

vent wipe.

Best results are obtained with the welding gun

positioned at about 90 degrees to the joint. Excessive

inclination can result in aspiration of air into the

shielding gas and cause porous or oxidized welds.

Slag entrapment is always a possibility with any

welding process involving a flux. Proper joint design

and bead placement is essential to ensure good

results. For multiple pass welds, beads should be

deposited so as to provide reasonable access to the

next bead to be deposited.

Submerged-Arc Welding

The submerged-arc process can be used to advantage

in many applications, especially for welds in thick

sections. For example, compared with automatic

gas metal-arc welding, submerged-arc welding pro-

vides 35-50% higher deposition rates, thicker beads,

a more stable arc, and smoother as-welded surfaces.

The process is also readily applicable to overlay

applications. Submerged-arc welding is usually done

with automated equipment. Because the low pene-

tration and viscous molten puddle of nickel alloys

require precise electrode positioning, manual (hand

held) submerged-arc welding is not recommended.

FLUX

Use of the proper flux is essential to successful sub-

merged-arc welding. In addition to protecting the

molten weld metal from atmosphere contamination,

the fluxes provide arc stability and contribute impor-

tant metallic additions to the weld deposit.

The flux burden should be only sufficient to

prevent arc breakthrough. Excessive amounts of

flux can cause defects, such as “pock” marks, craters,

and embedded flux. Conventional submerged-arc

welding equipment may require modification to be

usable with SMC’s submerged-arc welding fluxes.

The flux delivery nozzle should be removed or adjust-

ed such that the flux is delivered in front of the torch

about 1-2 in. to a depth of about 3/4-7/8 in. deep.

Feeding the flux directly onto the arc can result in

excessive flux burden and the problems previously

described.

Fused flux (“slag”) is readily removed from most

joints and is self-lifting on exposed weld beads. The

slag is inert and should be discarded. Unfused flux

can be recovered by clean vacuum systems and

reused. To maintain optimum particle size, reclaimed

flux should be mixed with an equal amount of new

(unused) flux.

Submerged-arc fluxes are somewhat hygroscopic

and must be protected from moisture. The fluxes

should be stored in a dry area, and open containers of

flux should be resealed immediately after use. Flux

that has absorbed moisture can be reclaimed by bak-

ing at 600°F (315° to 480°C) for 2 hrs. Fused fluxes

TTaabbllee 55 -- TTyyppiiccaall SSuubbmmeerrggeedd AArrcc WWeellddiinngg PPaarraammeetteerrss

FFiilllleerr MMeettaallPPoollaarriittyy

TTrraavveell SSppeeeedd iinn//mmiinn

((mmmm//mmiinn))

4 INCONEL 82 0.062 (1.6) DCEP 250 30-33 8-11 (200-280) 7/8-1 (22-25)

0.093 (2.4) DCEP 250-300 30-33 8-11 (200-280) 7/8-1 (22-25)

5 MONEL 60 0.062 (1.6) DCEP 260-280 30-33 8-11 (200-280) 7/8-1 (22-25)

NI-ROD FC 55 0.093 (2.4) DCEP 300-350 28-30 8-12 (200-300) 3/4 (20)

6 Nickel 61 0.062 (1.6) DCEP 250 28-30 10-12 (250-300) 7/8-1 (22-25)

NI-ROD 44 0.062 (1.6) DCEP 250 32 10 (254) 1 (25)

NI-ROD 99 0.062 (1.6) DCEP 250 28-30 8-12 (200-300) 3/4 (20)

CF 36 0.045 (1.1) DCEP 230-260 31-34 8-12 (203-300) 1/2-3/4 (13-19)

CF 42 0.045 (1.1) DCEP 230-260 31-34 8-12 (203-300) 1/2-3/4 (13-19)

7 INCONEL 625 0.062 (1.6) DCEP 250-260 32-33 8-9 (200-230) 1.0 (25)

0.093 (2.4) DCEP 300-320 32-33 8-9 (200-230) 1.0 (25)

8 MONEL 67 0.062 (1.6) DCEP 280-300 31-33 7-9 (178-230) 7/8-1 (22-25)

0.093 (2.4) DCEP 300-400 34-37 8-10 (200-250) 7/8-1 (22-25)

NT 100 Nickel 61 0.062 (1.6) DCEP 250 28-30 10-12 (250-300) 7/8-1 (22-25)

NI-ROD 44 0.062 (1.6) DCEP 250 32 10 (254) 1 (25)

NI-ROD 99 0.062 (1.6) DCEP 250 28-30 10 (254) 1 (25)

CF 36 0.045 (1.1) DCEP 230-260 31-34 8-12 (203-300) 1/2-3/4 (13-19)

CF 42 0.045 (1.1) DCEP 230-260 31-34 8-12 (203-300) 1/2-3/4 (13-19)

NT 120 INCONEL C-276 0.062 (1.6) DCEP 260 31-32 8-10 (200-254) 7/8 (22)

INCO-WELD 686CPT 0.062 (1.6) DCEP 260 31-32 10 (254) 7/8 (22)

INCONEL 622 0.062 (1.6) DCEP 260 31-32 10 (254) 7/8 (22)

are less prone to absorb moisture compared to

agglomerated SAW fluxes.

FILLER METAL

Filler metals for submerged-arc welding are the

same as those used for gas metal-arc welding. Wire

diameters in the range of 0.045 to 0.093 in (1.1 to 2.4

mm) are used. The 0.062 in (1.6 mm) diameter is gen-

erally preferred. Small-diameter wire is useful for

welding this material, and the 0.093 in (2.4 mm)

diameter wire is used for heavy sections.

CURRENT

Direct current with either straight (DCEN) or

reverse polarity (DCEP) is used. Reverse polarity is

preferred for butt welds because it produces flatter

beads with deeper penetration at low arc voltage (30-

33 V). Straight polarity is preferred for overlaying

because it gives a slightly higher deposition rate and

less penetration. Straight polarity requires a deeper

flux burden which results in increased flux consump-

tion. Straight polarity is best used with an oscillating

technique for overlaying. Depositing stringer beads

with straight polarity is not recommended due to

poor wetting and “ropy” bead shape and the resulting

lack of fusion defects.

WELDING PROCEDURE

Recommended joint designs for submerged-arc butt

welding are shown in Figure 4 (page 5). Typical con-

FFlluuxx TTyyppee

WWiirree DDiiaammeetteerr

iinn ((mmmm))

CCuurrrreenntt

((AAmmppss))

VVoollttaaggee

((VV))

EElleeccttrrooddee

EExxtteennssiioonn

iinn ((mmmm))

Figure 7. INCONEL alloy 600 joint 3-in (76-mm) thick com-

pleted with 0.062-in. (1.6-mm) diameter INCONEL Filler

Metal 82 and INCOFLUX 4 Submerged Arc Flux (numerals

indicate sequence of bead placement).

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FFiilllleerr MMeettaall

4 INCONEL 82 INCONEL 600 Bal 0.07 3.21 1.75 0.006 0.40 – 19.25 0.17 3.38 – –

5 MONEL 60 MONEL 400 Bal 0.06 5.0 3.5 0.013 0.90 26.0 – 0.48 – – –

NI-ROD FC 55 Ductile Iron 50 1.0 4.2 44 – 0.60 – – – – – –

6 Nickel 61 Nickel 200 89 0.07 0.4 8.5 0.004 0.65 – – 1.7 – – –

& NI-ROD 44 Ductile Fe Bal 0.7 10 60 – – – – – – – –

NT100 NI-ROD 99 Ductile Fe 83.5 0.01 0.26 14.9 0.005 0.40 – 0.01 0.03 – 0.01 –

CF 36 NILO 36 36.0 0.2 1.5 60.8 – – – – – 1.5 – –

CF 42 NILO 42 42 0.2 1.5 Bal – – – – – 1.5 – –

7 INCONEL 625 INCONEL 625 60.15 0.02 0.74 0.75 0.001 0.29 – 21.59 0.13 3.29 8.60 –

8 MONEL 67 Cu-Ni 35 0.01 0.70 0.5 0.006 0.50 63 – 0.25 – – –

NT120 INCONEL C-276 INCONEL C-276 59 0.002 0.93 5.5 0.001 0.2 0.016 16 0.03 0.35 15 3.5

INCO-WELD 686CPT INCONEL 686 58 0.01 0.8 1.1 0.004 0.32 0.007 20 0.03 0.075 16.2 4.0

INCONEL 622 INCONEL 622 59 0.005 0.75 0.75 0.001 0.25 0.008 20.4 0.03 0.27 14 3.3

FFlluuxx

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TTyyppiiccaall MMeecchhaanniiccaall PPrrooppeerrttiieess..

FFiilllleerr MMeettaall

4 INCONEL 82 97 (669) 55 (379) 35 – 70-80 –

5 MONEL 60 75 (517) 40 (276) 40 – – –

NI-ROD FC 55 65-80 (450-550) 45-55 (300-380) 15-20 – – –

6 Nickel 61 68 (469) 38 (262) 32 38 – –

NI-ROD 44 92 (635) 58 (400) 26 42 – –

NI-ROD 99 65 (450) 45 (310) 10-15 20 – –

CF 36 71.5 (493) 49.8 (343) 29 – – 72 (98)

CF 42 – – – – – –

7 INCONEL 625 107.7 (743) 63.8 (440) 40 39 73 (99)* 52.5 (71)*

8 MONEL 67 – – – – – –

NT100 Nickel 61 68 (469) 38 (262) 32 38 – –

NI-ROD 44 92 (635) 58 (400) 26 42 – –

NI-ROD 99 65 (450) 45 (310) 10-15 20 – –

CF 36 71.5 (493) 49.8 (343) 29 – – 72 (98)

CF 42 71.5 (493) 49.8 (343) 29 – – –

NT120 INCONEL C-276 105.8 (729) 62 (427) 49.8 35.6 55 (75) –

INCO-WELD 686CPT 106.4 (734) 63.3 (436) 45.1 50 – –

INCONEL 622 99.8 (688) 56.2 (387) 51.2 43.5 – –

FFlluuxx

TTyyppee

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kkssii ((MMPPaa))

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00..22%% OOffffsseett,, kkssii ((MMPPaa))

EElloonnggaattiioonn

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* Impact values from 625 and INCOFLUX 7 on 9% Nickel Steel.

ditions for submerged-arc welding with various

flux/filler-metal combinations are given in Table 5.

Typical chemical compositions and mechanical prop-

erties of weld metal from submerged-arc groove welds

are shown in Table 6.

Slag entrapment is a possibility during any weld-

ing operation involving flux. The problem can be con-

trolled by the use of an appropriate joint design and

proper bead placement. In a multipass welding,

beads should be placed so as to provide an open or

reasonably wide root for the next bead. Figure 7 illus-

trates bead placement in a 3-in (76-mm) thick groove

weld in INCONEL alloy 600.

Bead contour is important. Slightly convex beads

(a) Approximately 1/2 in (13 mm) intervals beginning at top surface.

EElleemmeennttLLeevveell 11LLeevveell 22LLeevveell 33LLeevveell 44LLeevveell 55LLeevveell 66

Nickel 73.6 73.5 73.6 73.5 73.7 73.6

Chromium 18.1 18.0 18.1 18.0 18.1 18.0

Niobium 3.61 3.71 3.59 3.67 3.50 3.60

Iron 0.86 0.87 0.88 0.88 0.87 1.00

Silicon 0.44 0.44 0.43 0.43 0.44 0.44

Carbon 0.05 0.05 0.05 0.05 0.05 0.05

Sulfur 0.003 0.003 0.003 0.003 0.003 0.003

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LLeevveellssaaooff aa 33--iinn ((7766--mmmm)) TThhiicckk JJooiinntt iinn

IINNCCOONNEELL aallllooyy 660000 WWeellddeedd wwiitthh IINNCCOONNEELL

FFiilllleerr MMeettaall 8822 aanndd IINNCCOOFFLLUUXX 44 SSuubbmmeerrggeedd

AArrcc FFlluuxx

IImmppaacctt SSttrreennggtthh

are essential. Flat or concave beads are prone to cen-

terline cracking. Bead contour is most effectively con-

trolled by voltage and travel speed. Higher voltage

and travel speed results in flatter beads.

By the use of proper welding procedures, excellent

results are attainable when submerged-arc welding

heavy sections of nickel alloy products. Six inch

(150 mm) INCONEL alloy 600 plates have been

successfully welded from one side (single U-joint

design) in the fully restrained condition with

INCOFLUX 4 Submerged-Arc Flux and INCONEL

Filler Metal 82.

Weld composition remains essentially constant

through the thickness of heavy section weldments

with no accumulation of flux components. Table 7

Figure 8. Optimum electrode position for submerged-arc

circumferential welding.

End View

90˚

3˚ ElectrodeElectrode

Side View

Workpiece

lists compositions of samples removed at 1/2-in (13-

mm) intervals from the top surface of a 3-in (76-mm)

thick weld.

Circumferential welding of groove joints in pipe is

performed with the same procedures used for groove

joints in plate. The degree of difficulty increases as

the pipe diameter decreases. Welding parameters

must be adjusted accordingly. Six-inch (150-mm)

diameter is the practical minimum that may be read-

ily welded. The major difficulty in pipe welding is

preventing the molten slag from flowing either into

or away from the weld metal as the pipe is rotated.

The electrode position can be used to control weld-

metal dilution and bead shape (Figure 8). Pipe diam-

eter and joint design influence the operable electrode

positions. Better control of fusion and penetration

can be achieved by the use of the gas tungsten-arc

process for the root pass.

Plasma-Arc Welding

The plasma-arc process can be used to advantage for

joining nickel alloys in thicknesses from 0.1 to 0.3 in.

Thicknesses outside that range can be plasma-arc

welded, but better results can usually be obtained

with other welding processes.

An important application of the plasma-arc

process is the welding of thicknesses up to 0.3 in.

without the use of filler metal. That thickness is sig-

nificantly greater than the limiting thickness for

autogenous welding by the gas tungsten-arc process.

Filler metal is normally required for gas tungsten-

arc welding of material greater than 0.1 in. thick.

The following discussion applies specifically to

automatic welding by the “keyhole” method of opera-

tion and with a transferred arc. With the keyhole

method, the plasma stream completely penetrates

the joint, and fusion occurs at the trailing edge of the

keyhole-shaped penetrated area resulting from

movement of the torch along the joint.

GAS

The orifice gas has a significant effect on the depth of

penetration and the configuration of the penetration

pattern. Argon or a mixture of argon and 5 to 8%

hydrogen gives good results in autogenous keyhole

welding. Starting of the torch becomes more difficult

as hydrogen is added to the gas. The same gas sup-

ply is normally used for both the orifice and outer-

shield gas.

CURRENT

Power sources for plasma-arc welding are similar to

those for gas tungsten-arc welding. Straight-polarity

direct current is used.

WELDING PROCEDURE

The joint surfaces must permit a tight fit with no

gaps. Sheared or saw-cut edges are usually ade-

quate. Clamping fixtures must be used to maintain

joint fit-up. The backup bar should have a

3/4-in. relief for venting of the plasma gas. The weld

root should be protected by inert gas introduced

through the backup bar.

Typical welding conditions for various thicknesses

of several alloys are given in Table 8. Amperage, gas

flow, and travel speed must be in the proper relation

to provide consistent keyholing. Turbulence in the

weld puddle can result from an unstable keyhole.

One indication of a proper keyhole is a consistent

stream of plasma gas flowing from the bottom of the

joint. Figure 9 shows the relation of travel speed to

amperage. Excessive travel speeds can cause under-

cutting and should be avoided.

Undercutting can also be caused by an inclined

Figure 9. Travel speed and amperage required

for keyholing.

100

120

140

160

180

200

220

240

260

246810121416182022

Current, amp

Travel Speed, ipm

Nickel 200 INCONEL

alloy 600

MONEL

alloy 400

INCOLOY

alloy 800

torch and by joint mismatch. The torch must be

maintained perpendicular to the joint in both lon-

gitudinal and transverse directions. The torch must

also be kept on the joint centerline. A deviation of

0.040 in. can be sufficient to cause lack of fusion.

Torch-to-work distances are normally 1/8 to 3/16 in.

Longer distances result in porosity; shorter distances

can result in spatter accumulation on the orifice.

A small amount of filler metal can be added dur-

ing welding by the keyhole method. The amount is

limited by the ability of the puddle’s surface tension

to support additional molten metal.

Joints in material over 0.3 in. thick can be plasma-

arc welded by use of the keyhole method, without

filler metal, for the root pass, followed by a non-key-

holing pass with filler metal added.

Overlaying

Nickel-base, corrosion-resistant alloys are needed in

many applications to provide protection from corro-

sive environments. However, in many cases, the com-

parative high cost of these base materials makes the

weld deposit of a protective layer on less expensive

load-bearing mild or low alloy steel the most realistic

financial alternative.

Nickel-alloy weld metals are readily applied as

overlays on most structural grades of steel. For best

results, iron dilution must be kept at minimum lev-

els. Excessive amounts of iron in the overlay com-

promise the corrosion resistance of the overlay and

can cause weld cracking.

The same welding processes used for joining alloy

components can also be used for overlaying.

However, submerged-arc welding is the process most

commonly used for overlaying.

As with all nickel-alloy welding applications, base

metal cleanliness is essential. All oxides and foreign

material must be removed from the surface to be

overlaid. The procedures and precautions discussed

under “Surface Preparation” should be carefully fol-

lowed.

AAllllooyy

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((iinn))((iinn))((ccffhh))((aammppss))((vvoollttss))((iippmm))

0.325 0.136 10.0 310 31.5 9

0.287 0.136 10.0 250 31.5 10

0.235 0.136 10.0 245 31.5 14

0.125 0.136 10.0 160 31.0 20

0.250 0.136 12.5 210 31.0 14

0.260 0.136 12.5 210 31.0 17

0.195 0.136 12.5 155 31.0 17

0.325 0.155 14.0 270 31.5 11

0.230 0.136 12.5 185 31.5 17

0.125 0.136 10.0 115 31.0 18

Nickel 200

MONEL alloy 400

INCONEL alloy 600

INCOLOY alloy 800

(a) Orifice and outershield gas: 95% argon, 5% hydrogen. Outershield flow rate: 45 cfh.

Cracking can sometimes occur in the first layer of

nickel-base overlays on grades of steel that contain

high levels of sulfur. When this occurs, the cracked

overlay should be removed and a buffer layer of car-

bon-steel weld metal deposited onto the sulfur-bearing

steel base material. The nickel-alloy overlay can then

be redeposited.

Nickel-alloy overlays can be applied to some grades

of iron castings. To determine if the casting is weld-

able, a trial overlay should be attempted. If the casting

skin or as-cast surface is not removed, then a flux con-

taining NI-ROD 99X or NI-ROD 55 Welding Electrode

will aid in removing deleterious elements on the sur-

face of the casting. For higher production rates for

unprepared casting surfaces, NI-ROD FC55 should aid

in removing any casting skin issue to produce sound

weld deposits. When overlays are applied directly to

cast iron without a barrier layer, amperage should be

kept at a minimum to keep dilution at the lowest level

possible.

SHIELDED METAL-ARC OVERLAYS

Because of the versatility and portability of the

process, shielded metal-arc welding is often used for

in-situ overlay steel components. Applications such as

facing on vessel outlets and trim on valves are com-

mon. SMAW is also well suited for overlay of cast iron

parts. NI-ROD and NI-ROD 55 Welding Electrodes

deposit a sound buffer layer that can be used as a base

for other alloy overlays.

The procedures outlined for shielded metal-arc join-

ing are equally applicable for overlaying. Special care

must be taken to control iron dilution of the overlay.

Excessive dilution can compromise weld properties

and soundness as well as corrosion resistance. Welds

with too much iron are generally incapable of passing

bend qualification tests (Figure 10).

The current for weld overlay with SMAW should be

in the lower half of the recommended range for the

electrode. The arc force should be directed at the

fusion line of the previous bead so that the weld metal

will spread onto the steel with only minimum weaving

of the electrode. If deposits with thin feather edges are

applied, more layers will be required and the possi-

bility of excessive dilution will be greater. The pene-

tration pattern or underbead contour of the overlay

should be as smooth as possible.

GAS METAL-ARC OVERLAYS

Gas metal-arc welding with spray transfer is often

used for high-deposition overlaying of steel compo-

nents with nickel-alloy filler metals. The overlays are

usually produced with mechanized equipment and

with oscillation of the electrode.

Pure argon is often used as a shielding gas. The

addition of 15 to 25% helium has been found to be

beneficial for overlays of nickel and nickel-chromium

welding products. Beads become wider and flatter

with reduced penetration as the helium content is

increased to about 25%. Gas-flow rates are influ-

enced by welding technique and will vary from 25 to

100 ft3/h (0.99 to 2.83 m3/h). As welding current is

increased, the weld puddle will become larger and,

thus, larger gas cups are required for protection. The

cup should be large enough to deliver an adequate

quantity of gas under low velocity to the overlay

area. When oscillation is used, a trailing shield may

be necessary for adequate protection. It also must be

considered that when air-cooled torches designed to

use carbon dioxide shielding gas are used with inert

gas shielding, the duty cycle of the torch must be de-

rated due to the decreased thermal conductivity of

the inert gases.

The chemical compositions of automatic gas

metal-arc overlays are shown in Table 9 (page 18).

The overlays were produced with the following weld-

ing parameters and conditions:

Torch gas, 50 ft3/h (1.4 m3/h) argon

Trailing shield, 50 ft3/h (1.4 m3/h) argon

Electrode extension, 3/4 in (19 mm)

Power source, reverse-polarity (DCEP)

Oscillation frequency, 70 cycles/min

Oscillation width, 7/8 in (22 mm)

Bead overlap, 1/4 to 3/8 in (6.4 to 9.5 mm)

Travel speed, 4 1/2 in/min (114 mm/min)

When nickel-copper or copper-nickel overlays

are to be applied to steel by GMAW, a barrier layer of

Nickel Filler Metal 61 must be applied first. The

nickel weld metal will tolerate greater iron dilution

without fissuring than will the copper-bearing weld-

ing products.

GAS METAL-ARC WELDING

PULSING TRANSFER

When a single pass overlay is being considered or

when overlays are applied manually, the iron content

of the first bead will be considerably higher than that

of subsequent beads. The first bead should be applied

using a low energy process such as pulsed-arc at a

reduced travel speed to dissipate much of the digging

Figure 10 - Manual shielded-metal-arc overlays. (a) Overlay with scalloped underbead contour.

(b) Bend-test specimen with cracks caused by improper underbead contour.

(d) Bend-test specimen from overlay shown in (c).

(a) (b)

force of the arc and, thus, reduce the iron content of

that bead. The iron content and surface contour of

subsequent beads of the overlay can be controlled by

use of the stringer bead technique and directing the

arc at the edge of the preceding bead. Such a proce-

dure will result in a 50% overlap of beads without

excessive arc impingement. The welding gun should

be inclined up to 5 degrees away from the preceding

bead so that the major force of the arc impinges on

the preceding bead, not on the steel being overlaid.

Solid State Pulsed Gas Metal Arc Welding

(P-GMAW) has helped nickel base filler metals for

low heat input welding application. Low heat input

P-GMAW maximizes the corrosion resistance of the

as-deposited weld, for not only joining, but also weld

overlaying of stainless and steel pipe, vessels, heat

exchanger tube-sheets and water-wall tubes. Solid

state P-GMAW power sources can offer a stable arc

with high helium levels with argon and in some cases

pure helium can be used allowing for improved wet-

ting while maintaining low amperage weld deposits

with a significantly lower potential for weld toe lack

of fusion defects. One of the primary filler metal

properties that has a significant effect on the

P-GMAW welding parameters, as well as weld

deposit dilution, is the “burn-off” rate. Each filler

metal composition will have a unique burn-off rate

based on the composition of the filler metal. Figure

11 illustrates how different burn-off properties of

various Ni-Cr-Mo filler metals can affect the P-

GMAW weld deposit iron dilution from the steel sub-

Figure 11. - Wt% Iron vs. Layer No. & Alloy Ni-Cr-Mo overlay

on mild steel P-GMAW-pulsing transfer, 100% helium, 0.045 in

(1.1 mm) diameter.

0.0

3.0 1

6.0

INCO-WELD

Filler Metal

686CPT

INCONEL

Filler Metal

622

INCONEL

Filler Metal

C-276

INCONEL

Filler Metal

625

N06022

9.0

Weld Deposit, Wt% Iron

12.0

Layers 1, 2, 3

Iron Contribution

Filler Metal =

Substrate =

15.0

(a) Automatic overlays with 0.062-in (1.6-mm) dia. filler metal on SA 212 Grade B steel. See text for additional welding conditions.

(b) First layer applied with Nickel Filler Metal 61.

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Nickel

Filler Metal 61

MONEL

Filler Metal 60b

MONEL

Filler Metal 67b

INCONEL

Filler Metal 82

INCONEL

Filler Metal C-276

INCONEL Filler

Metal 622

INCONEL Filler

Metal 686CPT

UNS N06022

Filler Metal

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280-290 27-29 1 71.6 25.5 – – 0.12 0.28 0.005 0.32 – 2.08 0.06 – – –

2 84.7 12.1 – – 0.09 0.17 0.006 0.35 – 2.46 0.07 – – –

3 94.9 1.7 – – 0.06 0.09 0.003 0.37 – 2.76 0.08 – – –

280-300 27-29 2 66.3 7.8 – 19.9 0.06 2.81 0.003 0.84 0.008 2.19 0.05 – – –

3 65.5 2.9 – 24.8 0.04 3.51 0.004 0.94 0.006 2.26 0.04 – – –

280-290 27-28 2 41.1 11.5 – 45.8 0.04 0.53 0.007 0.14 – 0.83 – – – –

3 35.6 3.1 – 60.1 0.01 0.61 0.006 0.08 – 0.43 – – – –

280-300 29-30 1 51.3 28.5 15.8 0.07 0.17 2.35 0.012 0.20 0.017 0.23 0.06 1.74 – –

2 68.0 8.8 18.9 0.06 0.040 2.67 0.008 0.12 1.015 0.30 0.06 2.27 – –

3 72.3 2.5 19.7 0.06 0.029 2.78 0.007 0.11 0.020 0.31 0.06 2.38 – –

n/a n/a 1 54.9 11.2 15.0 – 0.008 0.382 – 0.021 – – – – 14.4 3.51

2 58.0 6.5 15.8 – 0.007 0.388 – 0.020 – – – – 15.2 3.70

3 58.5 5.7 16.0 – 0.005 0.393 – 0.019 – – – – 15.3 3.73

n/a n/a 1 57.4 4.5 20.0 – 0.004 0.212 – 0.027 – – – – 14.0 3.29

2 57.5 3.0 20.0 – 0.002 0.213 – 0.027 – – – – 14.0 3.30

3 58.7 2.5 20.5 – 0.002 0.212 – 0.026 – – – – 14.2 3.35

n/a n/a 1 56.9 2.0 20.3 – 0.006 0.227 – 0.019 – – – – 16.2 3.89

2 57.3 1.3 20.4 – 0.004 0.229 – 0.019 – – – – 16.3 3.91

3 57.5 1.1 20.5 – 0.004 0.230 – 0.020 – – – – 16.3 3.91

n/a n/a 1 54.5 8.3 20.2 – 0.008 0.224 – 0.033 – – – – 12.6 2.96

2 57.0 4.3 21.1 – 0.002 0.222 – 0.032 – – – – 13.2 3.10

3 57.4 3.7 21.2 – 0.002 0.222 – 0.032 – – – – 13.2 3.12

strate. INCO-WELD 686CPT filler metal has a high-

er burn-off rate due primarily to the high level of

refractory elements in its chemical composition.

P-GMAW also offers excellent low heat input out

of position welding of thin sheet materials for

cladding applications (wallpapering). Seal welds and

attachment welds are required when lining mild

steel and/or stainless steel structural components for

service in highly corrosive wet environments.

SUBMERGED-ARC OVERLAYS

The submerged arc process produces high quality

nickel-alloy overlays on carbon steel and low-alloy

steel. The process offers several advantages over gas-

metal arc overlaying:

1. Higher deposition rates, 25-50% increase with

0.062 in (1.6 mm) diameter filler metal and the

4 INCONEL 82 0.062 (1.6) 1 63.5 0.07 2.95 12.5 0.008 0.40 – 17.00 0.15 – 3.4 – –

2 70.0 0.07 3.00 5.3 0.008 0.40 – 17.50 0.15 – 3.5 – –

3 71.5 0.07 3.05 2.6 0.008 0.40 – 18.75 0.15 – 3.5 – –

5 MONEL 60 0.062 (1.6) 1 60.6 0.06 5.00 12.0 0.014 0.90 21.0 – 0.45 – – – –

2 64.6 0.04 5.50 4.5 0.015 0.90 24.0 – 0.45 – – – –

6 Nickel 61 0.062 (1.6) 2 88.8 0.07 0.40 8.4 0.004 0.64 – – 1.70 – – – –

INCONEL 82 0.062 (1.6) 2 68.6 0.04 3.00 7.2 0.007 0.37 – 18.50 – – 2.2 – –

INCONEL 625 0.062 (1.6) 2 61.0 0.06 0.34 6.1 – 0.30 – 20.4 – 3.1 – 8.4 –

7 INCONEL 625 0.062 (1.6) 1 60.2 0.02 0.74 3.6 0.001 0.29 – 21.6 0.13 – 3.29 8.60 –

8 MONEL 67b0.062 (1.6) - 27.5 0.03 1.10 8.0 – 0.02 63.3 – – – – – –

NT 100 NICKEL 61 0.062 (1.6) 2 88.8 0.07 0.40 8.4 0.004 0.64 – – 1.70 – – – –

INCONEL 82 0.062 (1.6) 2 68.6 0.04 3.00 7.2 0.007 0.37 – 18.50 – – 2.2 – –

INCONEL 625 0.062 (1.6) 2 61.0 0.06 0.34 6.1 – 0.30 – 20.4 – 3.1 – 8.4 –

NT110 MONEL 60 0.062 (1.6) FM 64.99 0.047 3.62 0.66 – 0.95 27.70 – – – – – –

1 48.19 0.036 5.28 23.83 – 0.67 21.48 – – – – – –

2 57.15 0.027 5.46 11.13 – 0.68 25.02 – – – – – –

3 62.38 0.024 5.65 3.83 – 0.69 26.95 – – – – – –

4 63.84 0.029 5.02 1.47 – 0.85 27.92 – – – – – –

MONEL 67b0.062 (1.6) FM 30.21 0.008 0.75 0.49 – 0.10 68.07 – – – – – –

1 30.27 0.003 0.84 1.77 – 0.02 65.46 – – – – – –

NT 120 INCONEL C-276 0.062 (1.6) FM 58.89 0.004 0.39 5.55 0.001 0.009 0.020 15.98 0.02 0.09 – 15.36 3.76

1 46.67 0.007 0.91 22.4 0.0003 0.136 0.014 13.41 0.016 0.146 – 12.46 3.57

2 53.90 0.013 0.94 12.59 0.005 0.165 0.010 15.02 0.023 0.323 – 13.68 3.23

3 56.74 0.006 0.95 8.05 0.003 0.180 0.180 15.73 0.025 0.331 – 14.44 3.43

4 57.75 0.002 0.93 6.47 0.0001 0.168 0.006 15.75 0.03 0.348 – 14.95 3.49

INCO-WELD 0.062 (1.6) FM 57.88 0.004 0.220 1.07 0.001 0.010 0.010 20.31 0.05 0.060 – 16.28 3.90

686CPT 1 46.80 0.007 0.819 18.42 0.0001 0.321 0.004 17.19 0.02 0.477 – 13.45 3.38

2 53.97 0.007 0.747 4.81 0.0001 0.344 0.003 18.82 0.03 0.482 – 16.04 4.23

3 55.68 0.007 0.697 2.24 0.0001 0.333 0.003 19.09 0.03 0.445 – 16.45 4.26

4 55.97 0.007 0.711 1.42 0.0001 0.349 0.002 19.11 0.03 0.476 – 16.83 4.26

INCONEL 622 0.062 (1.6) FM 59.06 0.001 0.23 2.4 0.001 0.02 0.01 20.45 0.05 0.0l – 14.38 3.39

1 40.48 0.026 0.852 31.76 0.001 0.196 0.009 15.04 0.02 0.213 – 9.28 2.04

2 50.48 0.007 0.722 13.90 0.001 0.182 0.007 18.78 0.03 0.257 – 12.21 3.10

3 54.58 0.004 0.739 7.20 0.0003 0.189 0.006 19.93 0.03 0.285 – 13.52 3.22

4 56.50 0.005 0.711 4.33 0.001 0.243 0.008 20.34 0.03 0.269 – 14.05 3.36

TTaabbllee 1100 -- TTyyppiiccaall CChheemmiiccaall CCoommppoossiittiioonn ooff SSuubbmmeerrggeedd AArrcc OOvveerrllaayyss oonn SStteeeellaa

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(a) Overlays on ASTM SA 212 Grade B steel or A36 carbon steel.

(b) When overlaying steel with MONEL 67 a barrier layer of NICKEL 61 is required.

ability to use larger electrodes.

2. Fewer layers are required for a given overlay

thickness. For example, with 0.062 in (1.6 mm)

filler metal, two layers applied by the submerged-

arc process have been found to be equivalent to

three layers applied by the gas metal arc process.

The chemical composition of submerged-arc over

lays are found in Table 10.

3. The welding arc is much less affected by minor

process variations such as wire condition and elec-

trical fluctuations.

4. As-welded surfaces smooth enough to be dye-pen-

etrate-inspected with no special surface prepara-

tion other than wire brushing.

5. Direct applications of nickel-copper alloy on steel

without a nickel barrier layer.

6. The increased control provided by the submerged

arc overlaying process generally yields fewer

defects and repairs along with no arc flash and lit-

tle smoke.

In addition, the increased control provided by the

submerged-arc process generally yields fewer defects

and repairs.

Typical conditions for submerged arc overlaying

with various flux/filler metal combinations are given

in Table 11. Chemical compositions of overlay

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4 INCONEL 82 0.062 (1.6) DCEN 240-260 32-34 3.5-5 (89-130) 7/8-1 (22-25) 45-70 7/8-1.5 (22-38)

0.093 (2.4) DCEN 300-400 34-37 3-5 (76-130) 1 1/8-2 (29-51) 35-50 1-2 (25-51)

5 MONEL 60 0.062 (1.6) DCEN 260-280 32-35 3.5-6 (89-150) 7/8-1 (22-25) 50-70 7/8-1.5 (22-38)

0.093 (2.4) DCEN 300-400 34-37 3-5 (89-130) 1 1/8-2 (29-51) 35-50 1-2 (25-51)

0.062 (1.6) DCEP 260-280 32-35 7-9 (180-230) 7/8-1 (22-25) – –

0.093 (2.4) DCEP 300-350 35-37 8-10 (200-250) 1.25-1.5 (32-38) – –

NI-ROD FC 55 – – – – – – – –

6 NICKEL 61 0.062 (1.6) DCEN 250-280 30-32 3.5-5 (89-130) 7/8-1 (22-25) 50-70 7/8-1.5 (22-38)

INCONEL 82 0.062 (1.6) DCEN 240-260 32-34 3-5 (76-130) 7/8-1 (22-25) 45-70 7/8-1.5 (22-38)

0.093 (2.4) DCEN 300-400 34-37 3-5 (76-130) 1 1/8-2 (29-51) 35-50 1-2 (25-51)

INCONEL 625 0.062 (1.6) DCEN 240-260 32-34 3.5-5 (89-130) 7/8-1 (22-25) 50-60 7/8-1.5 (22-38)

NI-ROD 44 0.062. (1.6) DCEP 250 32-34 4.5 (114) 1 (25) 60 1 1/8 (29)

NI-ROD 99 0.035 (0.9) DCEN 160-200 27-30 4-6 (100-150) 1/2-1 (13-25) 50-80 1/2-1 1/4 (13-32)

0.035 (0.9) DCEP 160-200 27-30 9-11 (230-280) 1/2-1 (13-25) – –

0.045 (1.1) DCEN 200-240 30-33 4-6 (100-150) 3/4-1 1/8 (19-29) 50-80 1/2-1 1/4 (13-32)

0.045 (1.1) DCEP 200-240 30-33 9-11 (230-280) 3/4-1 1.8 (19-29) – –

0.062 (1.6) DCEN 240-260 32-34 4-6 (100-150) 3/4-1 1/8 (19-29) 50-80 1/2-1/1/4 (13-32)

0.062 (1.6) DCEP 240-260 32-34 10-12 (250-300) 3/4-1 1/8 (19-29) – –

CF 36 – – – – – – – –

CF 42 – – – – – – – –

7 INCONEL 625 0.062 (1.6) DCEN 250-260 32-33 5-6 (130-150) 0.75-1 (19-25) 60-80 0.75 (19)

0.093 (2.4) DCEN 300-320 32-33 5-6 (130-150) 0.75-1 (19-25) 50-70 0.875 (22)

8 MONEL 67 0.062 (1.6) DCEN 280-300 32-35 3.5-6 (89-150) 7/8-1 (22-25) 50-70 7/8-1.5 (22-38)

NT100 NICKEL 61 0.062 (1.6) DCEN 250-280 30-32 3.5-5 (89-130) 7/8-1 (22-25) 50-70 7/8-1.5 (22-38)

INCONEL 82 0.062 (1.6) DCEN 240-260 32-34 3-5 (76-130) 7/8-1 (22-25) 45-70 7/8-1.5 (22-38)

0.093 (2.4) DCEN 300-400 34-37 3-5 (76-130) 1 1/8-2 (29-51) 35-50 1-2 (25-51)

INCONEL 625 0.062 (1.6) DCEN 240-260 32-34 3/5-5 (89-130) 7/8-1 (22-25) 50-60 7/8-1.5 (22-38)

NI-ROD 44 0.062 (1.6) DCEP 250 32-34 4.5 (114) 1 (25) 60 1 1/8 (29)

NI-ROD 99 0.035 (0.9) DCEN 160-200 27-30 4-6 (100-150) 1/2-1 (13-25) 50-80 1/2-1 1/4 (13-32)

0.035 (0.9) DCEP 160-200 27-30 9-11 (230-280) 1/2-1 (13-25) – –

0.045 (1.1) DCEN 200-240 30-33 4-6 (100-150) 3/4-1 1/8 (19-29) 50-80 1/2-1 1/4 (13-32)

0.045 (1.1) DCEP 200-240 30-33 9-11 (230-280) 3/4-1 1/8 (19-29) – –

0.062 (1.6) DCEN 240-260 32-34 4-6 (100-150) 3/4-1 1/8 (19-29) 50-80 1/2-1 1/4 (13-32)

0.062 (1.6) DCEP 240-260 32-34 10-12 (250-300) 3/4-1 1/8 (19-29) – –

CF 36 – – – – – – – –

CF 42 – – – – – – – –

NT 110 MONEL 60 0.062 (1.6) DCEP 240-290 32-35 7-9 (178-229) 7/8-1 (22-25) – –

0.093 (2.4) DCEP 300-400 35-37 8-10 (203-254) 1.25-1.5 (32-38) – –

MONEL 67 0.062 (1.6) DCEP 240-290 32-35 7-9 (178-229) 7/8-1 (22-25) – –

0.093 (2.4) DCEP 300-400 35-37 8-10 (203-254) 1.25-1.5 (32-38) – –

NT 120 INCONEL C-276 0.062 (1.6) DCEP 235-245 33-34 4 (102) 7/8 (22) 30 1.5 (38)

INCO-WELD 686 CPT 0.062 (1.6) DCEP 235-245 33-34 4 (102) 7/8 (22) 30 1.5 (38)

INCONEL 622 0.062 (1.6) DCEP 235-245 33-34 4 (102) 7/8 (22) 30 1.5 (38)

deposits are shown in Table 9 (page 18).

The recommended power supply for all overlays

applied by oscillating techniques is constant-voltage

direct current with straight polarity (DCEN).

Straight polarity produces a less-penetrating arc

that reduces dilution. Reverse polarity, however,

should be used for stringer-bead overlays to mini-

mize the possibility of slag inclusions. When the

stringer bead technique is used, it is essential to use

50% bead overlap to control dilution. To maintain-

Figure 13. - Cross sections and surface of hot-wire plasma-arc overlays of INCONEL Filler Metal 82 on steel.

One Layer

Two Layers

constant dilution, it is sometimes desirable to apply

the first bead on a “waste strip” or by using a lower

dilution process such as pulsed GMAW.

The most efficient use of the submerged-arc

process for overlaying requires equipment capable of

oscillating the electrode. Pendulum oscillation is

characterized by a slight hesitation at both sides of

the bead. It produces slightly greater penetration

and somewhat higher iron dilution at those points.

Straight-line oscillation gives approximately the

same results as pendulum oscillation. Straight-line

constant-velocity oscillation produces the lowest

level of iron dilution. It provides for movement on a

horizontal path so that the arc is maintained con-

stant. The optimum movement is that which is pro-

grammed to have no end dwell, so that the deeper

penetration at either side resulting from hesitation is

eliminated. Figure 12 illustrates bead shapes result-

ing from various oscillation techniques.

Iron dilution is influenced by oscillation width as

well as by current, voltage, and travel speed.

Generally, iron dilution will decrease as oscillation

width is increased with oscillating overlays. Only

enough overlap to produce a smooth top surface is

required. Usually smooth tie-ins are produced using

1/8-inch overlap and 0.1 secs dwell at the previous

bead edge.

Non-oscillating techniques are sometimes used for

making narrow overlays in inaccessible areas where

oscillation is not practical. Bead placement is of the

utmost importance. Iron dilution and surface con-

tour are controlled by positioning the electrode 1/16

in (1.6 mm) away from the fusion line of the previous

bead to yield 50% bead overlap. The major reason for

bend test failure in stringer bead weld overlay quali-

fication tests is deeply scalloped penetration patterns

as shown in Figure 10 (page 17). This is caused by

locating the subsequent beads too far from the exist-

ing bead.

The flux depth should be sufficient only to prevent

arc breakthrough. The depth required will vary with

voltage and electrode diameter. As the voltage is

Figure 12. Basic submerged-arc oscillation techniques and

bead configurations.

Stringer

Bead Straight

Line

Straight

Line

Constant

Velocity

Pendulum

increased, the amount of flux overburden and the

amount of molten flux should be increased. Use of the

proper flux is essential. As with groove welding, a

fluxburden of about 3/4 - 7/8 in. is optimum. The use

of flux-delivery systems that direct the flux onto the

arc are not recommended.

Stress relieving of overlays is usually not required.

However, specifications may require stress relieving

of the steel being overlaid. A stress relief of 1150°F

(620°C) for 1 hr or more for each inch of thickness is

often sufficient. However, the requirements of weld-

ing specification should be considered as controlling.

HOT-WIRE PLASMA-ARC OVERLAYS

High-quality overlays can be produced at high depo-

sition rates with the hot-wire plasma-arc process.

The process offers precise control of dilution. Dilution

rates as low as 2% have been obtained. However, for

optimum uniformity and control over lack of fusion

defects, a dilution rate of 5 to 10% range is recom-

mended.

The highest deposition rates are produced by feed-

ing two filler-metal wires which are resistance-heat-

TTaabbllee 1122 -- CCoonnddiittiioonnss ffoorr HHoott--WWiirree PPllaassmmaa--AArrcc OOvveerrllaayyiinngg

MMOONNEELL FFiilllleerr MMeettaall 6600IINNCCOONNEELL FFiilllleerr MMeettaall 8822

Filler Metal Diameter, in (mm) 0.062 (1.57) 0.062 (1.57)

Plasma-Arc Power Source Straight-Polarity DCEN Straight-Polarity DCEN

Plasma-Arc Current, A 490 490

Plasma-Arc Voltage, V 36 36.5

Hot-Wire Power Source AC AC

Hot-Wire Current, A 200 175

Hot-Wire Voltage, V 17 23.5

Plasma Gas and Flow Rate 75% He, 25% A; 55 ft3/h (1.6 m3/h) 75% He, 25% A; 55 ft3/h (1.6 m3/h)

Outershield Gas and Flow Rate Argon; 40 ft3/h (1.1 m3/h) Argon; 40 ft3/h (1.1 m3/h)

Trailing Shield Gas and Flow Rate Argon; 45 ft3/h (1.3 m3/h) Argon; 45 ft3/h (1.3 m3/h)

Torch-to-Work Distance, in (mm) 13/16 (21) 13/16 (21)

Travel Speed, in/min (mm/min) 7-1/2 (190) 7-1/2 (190)

Oscillation Width, in (mm) 1-1/2 (38) 1-1/2 (38)

Oscillation Frequency, cycles/min 44 44

Deposit Width, in (mm) 2 (51) 2-3/16 (56)

Deposit Thickness, in (mm) 3/16 (4.8) 3/16 (4.8)

Deposit Rate, lb/h (kg/h) 40 (18) 40 (18)

Preheat, °F (°C) 250 (120) 250 (120)

(a) Overlay on ASTM A 387 Grade B steel made with 0.062 in (1.6 mm) diameter filler metal.

TTaabbllee 1133 -- CChheemmiiccaall CCoommppoossiittiioonn,, %%,, ooff HHoott--WWiirree PPllaassmmaa--AArrcc OOvveerrllaayyss oonn SStteeeellaa

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MONEL Filler Metal 60 1 61.1 5.5 – 27.0 0.07 3.21 0.006 0.86 2.14 0.05 –

2 63.1 1.5 – 28.2 0.07 3.32 0.006 0.88 2.25 0.04 –

INCONEL Filler Metal 82 1 68.3 8.3 18.4 0.05 0.02 2.67 0.010 0.16 0.24 – 2.16

2 73.2 1.7 20.2 0.02 0.01 2.86 0.010 0.17 0.24 – 2.31

ed by a separate AC power source. The filler metal is

nearly molten when it enters the weld puddle.

Deposition rates for nickel-alloy welds are 35-40 lb/h

(16-18 kg/h), approximately double those obtained

with submerged-arc overlaying.

Figure 13 shows the surface and cross section of a

hot-wire plasma-arc overlay made with INCONEL

Filler Metal 82. Side-bend tests performed on the

overlay showed no fissures.

Weld parameters for hot-wire plasma-arc overlay-

ing with INCONEL Filler Metal 82 and MONEL

Filler Metal 60 are given in Table 12. Chemical com-

positions of two-layer overlays made with those filler

metals are listed on Table 13.

STRIP WELDING OVERLAYS

Strip welding overlays can be produced with the

Electroslag Strip Surfacing (ESS) process and the

Submerged-Arc Strip Surfacing (SAS) process. The

ESS welding process is similar to the SAS welding

process except the nature of the ESS flux prevents

the formation of an arc. With the ESS welding

process the electrical resistivity of the molten slag

provides the heat source to melt the strip as opposed

to melting by electric arc as occurs with the SAS

welding process.

The ESS and SAS processes utilize identical

equipment. Both processes offer high deposition

rates (35-50 lbs/hr). Both processes are limited to

use in the flat (1G) position. However, the ESS

process results in 50% less dilution than the SAS

process. Weldstrip alloys and suggested parameters

are presented in Tables 14 and 15.

Welding Procedure

The strip should be cut on a 30 degree angle. The

point of the strip should be brought into contact

with the workpiece. The strip stick-out (distance

from the contact tip to the workpiece) is normally 1-

2 inches (25-50 mm). The recommended flux burden

is 0.5 - 1.0 inch (13 - 25 mm) deep and should ini-

tially surround the strip. During ESS welding, the

flux should be distributed to the leading edge of the

strip and the coverage should be maintained uni-

formly. When SAS welding is used the flux should be

distributed to both sides of the strip. Excessive flux

burden should beavoided during both ESS and SAS

welding; exces-sive flux and slag weight tends to

deform the weld surface.

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ESS1 82 ESW 1.2 (30) DCEP 600-800 24-25 5-8 (127-203) 60-70 (1524-1778) 1-2 (25-50) 0.5-1 (13-25)

ESW 2.4 (60) DCEP 1100-1300 24-25 5-8 (127-203) 60-70 (1524-1778) 1-2 (25-50) 0.5-1 (13-25)

625 ESW 1.2 (30) DCEP 600-800 24-25 5-8 (127-203) 60-70 (1500-1800) 1-2 (25-50) 0.5-1 (13-25)

ESW 2.4 (60) DCEP 1100-1300 24-25 5-8 (127-203) 60-70 (1500-1800) 1-2 (25-50) 0.5-1 (13-25)

686 CPT ESW 1.2 (30) DCEP 600-800 24-25 5-8 (127-203) 60-70 (1500-1800) 1-2 (25-50) 0.5-1 (13-25)

ESW 2.4 (60) DCEP 1100-1300 24-25 5-8 (127-203) 60-70 (1500-1800) 1-2 (25-50) 0.5-1 (13-25)

ESS2 52SCC ESW 1.2 (30) DCEP 600-700 23-24 6-7 (150-180) 65-70 (1650-1800) 0.75-1 (19-25) 0.75-1.5 (19-38)

ESW 2.4 (60) DCEP 1100-1300 23-24 6-7 (150-180) 65-70 (1500-1800) 0.75-1 (19-25) 0.75-1.5 (19-38)

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ESS1 82 Steel Overlay Weldstrip 0.047 2.92 0.11 20.07 – 2.42 1.23 72.74 –

1 0.046 3.07 0.32 20.24 – 2.03 3.26 70.79 –

2 0.045 3.05 0.24 20.95 – 2.08 1.63 71.93 –

3 0.04 3.05 0.24 21 – 2.03 1.53 72.05 –

ESS1 625 Steel Overlay Weldstrip 0.011 0.05 0.07 21.5 8.84 3.45 3.87 61.7 –

1 0.024 0.5 0.24 21.44 8.12 3.02 7.96 58.4 –

2 0.021 0.49 0.27 22.02 8.45 3.07 4.67 60.6 –

3 0.021 0.44 0.25 22.08 8.66 3.13 4.17 60.81 –

ESS1 686 CPT Steel Overlay Weldstrip 0.002 0.25 0.01 20.4 16.27 0.02 0.36 58.65 3.88

1 0.0009 0.57 0.06 19.75 14.99 0.03 5.28 54.71 3.88

2 0.0001 0.56 0.07 20.27 15.72 0.03 1.51 56.8 3.88

3 0.0001 0.57 0.07 20.39 15.95 0.03 0.57 57.36 3.88

ESS2 52SCC Steel Overlay Weldstrip 0.03 0.14 0.07 30.01 – 0.01 9.11 59.58 –

1 0.02 1.48 0.27 29.0 – 1.2 10.3 57.3 –

2 0.02 1.38 0.27 29.5 – 1.2 8.9 58.4 –

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SAS1 82 SAW 1.2 (30) DCEP 300-450 25-28 4-5 (102-127) 3/4-1 (19-25) 1-2 (25-50)

SAW 2.4 (60) DCEP 700-900 25-28 4-5 (102-127) 3/4-1 (19-25) 1-2 (25-50)

625 SAW 1.2 (30) DCEP 300-450 25-28 4-5 (102-127) 3/4-1 (19-25) 1-2 (25-50)

SAW 2.4 (60) DCEP 700-900 25-28 4-5 (102-127) 3/4-1 (19-25) 1-2 (25-50)

SAS2 52SCC SAW 2.4 (60) DCEP 700-900 25-28 4-5 (102-127) 3/4-1 (19-25) 1-2 (25-50)

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SAS1 82 Steel Overlay Weldstrip 0.047 2.92 0.11 20.07 – 2.42 1.23 72.74

1 0.040 3.10 0.30 17.86 – 1.95 14.9 64.1

2 0.037 3.25 0.38 19.84 – 2.01 2.87 71.16

3 0.037 3.35 0.38 19.92 – 2.05 1.57 71.27

SAS1 625 Steel Overlay Weldstrip 0.026 0.08 0.09 21.52 9.02 3.45 0.75 64.02

1 0.037 0.91 0.39 18.51 7.76 2.78 13.15 55.92

2 0.036 0.86 0.40 20.71 8.58 2.99 3.05 62.45

3 0.028 0.85 0.41 20.84 8.79 3.03 1.30 63.36

SAS2 52SCC Steel Overlay 2 0.01 0.83 0.25 29.05 – 0.82 9.32 57.35

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Welding Nickel Alloy

Clad Steel Plate

When only a thin section of a nickel alloy is required

to protect a component from corrosion, significant

savings are possible by fabricating it from alloy clad

steel plate instead of solid alloy plate. By the use of

clad steel plate, the steel substrate meets the struc-

tural requirements while the thin cladding of alloy

protects the components from corrosive attack. Alloy

clad steel plate typically costs half the price of solid

alloy plate.

Alloy clad steel plates are readily joined by con-

ventional welding processes and procedures using

standard nickel alloy welding products. Welding pro-

cedures must be designed to maintain the integrity

and corrosion resistance of the alloy cladding as well

as the strength of the steel substrate. This require-

ment influences welding product selection, joint

design, and welding technique. Dilution of iron into

the alloy weldment is to be avoided as the content of

iron compromises the weld’s corrosion resistance and

mechanical properties.

The choice of welding products for joining alloy

clad steel plate is critical. Due to the propensity for

iron dilution of the weldment, it is suggested that a

welding product more highly alloyed than the

cladding material be used to offset the effects of iron

dilution commonly encountered when welding clad

steel plate. For example, INCONEL alloy C-276 clad

steel plate is best joined with INCO-WELD 686CPT

welding products.

Thinner section clad steel plates (3/16 to 3/8 inch

steel backing plate) are normally joined with full

alloy welds. It may be more economical when weld-

ing heavier plate to weld most of the steel section

with steel welding products and only the alloy

cladding and a small portion of the steel backing with

the more expensive nickel alloy welding products.

Depositing steel weld metal over nickel alloy weld or

base metal is not recommended as diluting the alloy

constituents into the steel weld metal can cause

excessive hardness and cracking.

Clad steel plates are joined by techniques in which

welding takes place from only the steel side, only the

alloy side, or both sides. Accessibility and plate

thickness will generally dictate the welding scenario

to use. It is generally best to weld from both sides of

the clad steel plate when possible.

Thin section clad steel plate is best joined by weld-

ing from both sides with the first weld pass being

deposited on the cladding side by a technique such

that it does not fully penetrate the alloy cladding. In

this manner, the weld does not penetrate into the

steel substrate and iron dilution is avoided. The steel

substrate is then back chipped and the weld complet-

ed with the alloy welding product (Figure 14).

Joining heavy section clad steel plate from both

sides is preferable so that the steel substrate can be

welded with economical steel welding products.

Prepared joints should be used when possible.

Figures 15a and 15b shows recommended designs

for two thickness ranges. The preferred scenario is

that the steel portion of the clad steel plate is welded

first from the steel side with the steel welding prod-

uct appropriate for the specific grade of steel. It is

important to avoid penetration of the cladding by the

first welding pass as dilution of nickel and other

alloying elements into the steel weld can cause exces-

sive hardness and cracking. Also penetration of the

cladding with the steel weld compromises the corro-

sion-resistance of that portion of the cladding. The

joint designs in Figures 15a and 15b include a small

steel land to help avoid penetration of the steel weld

into the nickel alloy cladding. After welding of the

steel substrate is completed, a joint on the clad side

of the plate should be prepared by machining, grind-

ing, or chipping, as appropriate, and a weld deposited

with the desired alloy welding product. The service

weld on the clad side of the plate will be somewhat

Figures 15a & 15b. Joint designs for clad steel.

(A) Material 3/16 to 5/8 in. (4.8 to 16 mm) thick.

(B) Material 5/8 to 1 in. (16 to 25 mm) thick.

30 - 40˚

10 - 15˚

1/16"

(1.6 mm)

3/16 - 5/16"

(4.8 - 8.0 mm) R

Steel Steel

Alloy Cladding

Figure 14. Welding Alloy Clad Steel Plate – The above bead

sequence is typical for clad plate compromised of 1/16” alloy

cladding on 1/4” steel backing. An over-alloyed welding product

is recommended.

1. Deposit First Bead on Clad Side

3. Deposit 2nd Bead to Achieve

Full Penetration of 1st Bead

4. Deposit 3rd and 4th Beads as necessary

to complete the weldment

2. Back-Chip Joint by Grinding

Figure 16. Strip-back method of joint preparation.

Steel Steel

Cladding

diluted with iron from the steel weld and backing. To

maintain corrosion resistance, at least two (prefer-

ably three or more layers) should be deposited in

making the cladding weld. Also, the use of highly

alloyed welding products is suggested. When welding

must be done from only one side, conventional joint

designs are used. If welding is done from the alloy

side, the steel backing may be welded with steel

welding products with only the cladding and steel

interface being joined with the alloy welding prod-

uct. If welding must be done from the steel side only,

the complete joint should be deposited with the alloy

welding product. It must be considered that the

welds deposited from only one side will to some

degree be diluted with iron. Thus, their corrosion

resistance will be accordingly reduced. To offset the

effects of dilution highly alloyed overmatching weld-

ing products should be used.

To better control residual stresses and minimize

distortion when welding heavy sections of alloy clad

steel plate, a double “V” joint such as is seen in

Figure 15c or a double “U” or double “J” joint may be

preferred when both sides of the weld joint are acces-

sible. With this joint configuration, one side will be

welded with steel welding products. Depending on

the thickness of the plate being welded, the other

side of the joint may be deposited with alloy welding

products or it may be partially welded with steel

welding products and only the top layers of the joint

deposited with the more costly alloy welding prod-

ucts. The welding engineer is cautioned to be sure

that the effects of iron dilution are considered when

determining what portion of the weldment to make

with alloy welding products. As above, the use of

overmatching welding consumables is encouraged.

The “strip-back” technique is sometimes used

when joining heavy section clad steel plate. With this

method the cladding adjacent to the weld joint is

removed as shown in Figure 16. The steel substrate

is then welded using a standard joint design and

welding product. After the steel weld is completed,

the integrity of the cladding is restored by a weld

overlaying technique. The main advantage of the

strip-back method is that it eliminates the possibili-

ty of cracking caused by penetration of the steel weld

metal into the cladding.

Welding Metallurgy and Design

Nickel-alloy joining procedures must reflect any spe-

cial metallurgical aspects of the operation. And,

since many of the high performance alloys utilize

rather complex phenomena in developing high levels

of strength and corrosion-resistance, the welding

engineer must thoroughly understand the metallur-

gy of the base metal and the welding product.

Metallurgical factors strongly influence proce-

dures for welding dissimilar materials and precipita-

tion-hardenable alloys. Any welded joint can undergo

metallurgical changes when subjected to cold work

and heat treatment. For high-temperature service,

both metallurgical and design considerations are

important in obtaining life in fabricated equipment.

WELDABILITY

In developing a welding procedure, the engineer

must first affirm that the products of interest are

indeed weldable. The alloy’s composition, structure,

and thermal mechanical history all affect its

response to welding.

Wrought alloys generally exhibit better weldabili-

ty than castings. The dendritic structure of castings

often exhibits severe elemental segregation. Also,

castings often contain significant additions of silicon

for fluidity. Silicon can compromise the hot-cracking

resistance of some alloys and, thus, their weldability.

Materials with a coarse grain structure (ASTM

Number 5 or coarser) are generally found to be less

weldable than those with finer grain structures.

Coarse grain material are particularly prone to base

metal microfissuring. Grain size can restrict the use

of processes having high energy input (e.g., GMAW in

the spray mode of transfer and electron beam weld-

ing). Table 16 illustrates the effect of grain size on

selection of welding processes for several alloys.

Alloys are best welded in the annealed condition.

Alloys with high levels of residual stress due to

rolling, drawing, or forming can be prone to cracking.

Alloy products annealed at lower temperatures (mill

anneal) generally exhibit finer grain structures than

those annealed at higher temperatures (solution

anneal) and, thus, are found to offer a better welding

response. Some alloys must be solution annealed

prior to final heat treatment (e.g., precipitation hard-

enable alloys) or being placed into high temperature

service conditions (e.g., INCONEL alloy 601 or 617 or

Alloy Cladding Alloy Cladding

Steel Steel

Alloy Weld

Steel Weld (Note: Steel welds placed

before nickel alloy welds.)

Figure 15c. Double “V” joint.

INCOLOY alloy 800HT or 803). If possible, such

alloys should be welded after a mill anneal and prior

to the solution anneal.

DISSIMILAR WELDING

The information presented here can be used as a gen-

eral guideline in the selection of a welding product

for a dissimilar joint. The effects of mixing dissimi-

lar materials are too complex to permit prediction of

results with absolute certainty in all cases. However,

with an accurate estimate of dilution rates, the pro-

cedures outlined will eliminate needless trials by

showing which electrodes and filler metals have a

high probability for success.

1) General Guidelines

Dissimilar welding often involves complex metallur-

gical considerations. The composition of the weld

deposit is controlled not only by the electrode or filler

metal but also by the amount of dilution of elements

from the two base metals joined. The amount of dilu-

tion varies with the welding process, the operator

technique, and the joint design. All of these influence

the selection of a joining method and a welding mate-

rial that will produce a welded joint having the prop-

erties required by the application.

Some Special Metals welding products are

especially applicable to dissimilar joining applica-

tions. Welding product recommendations for many

frequently encountered dissimilar joints are given

in Table 17 (pages 30 and 31). For more specific

recommendations, contact Special Metals Weld-

ing Products Company or visit the website,

www.specialmetalswelding.com. The nickel-

chromium electrodes and filler metals, INCO-WELD

A, B, C, and 686CPT Electrodes, INCONEL Welding

Electrodes 112, 122 and 182, INCONEL Filler Metals

82, 622 and 625, and INCO-WELD 686CPT Filler

Metal are particularly versatile materials for dissim-

ilar welding. They can tolerate dilution from a vari-

ety of base metals without becoming crack-sensitive.

In many cases, more than one welding product will

satisfy the requirement of metallurgical compatibili-

ty. The selection of the optimum product will be

determined by the requirements for strength, rigors

of the service environment, and economics. In gener-

al, the weld should be at least as strong at the oper-

ating temperature as the weakest material in the

dissimilar joint. Corrosion resistance to the service

environment is critical. For example, INCOLOY

alloy 825 may in theory be welded with either INCO-

WELD A Welding Electrode or INCONEL Welding

Electrode 112. If the weldment is to be exposed to a

corrosive environment, Welding Electrode 112 will

likely be preferred because of its superior corrosion

resistance. However, if a low carbon steel beam is to

be welded to the exterior of an alloy 825 vessel for

structural reinforcement, INCO-WELD A might be

preferred. It meets the strength requirement for

joining steel to alloy 825 (it is stronger than the low

carbon steel beam) and it is lower in cost than

Welding Electrode 112.

Sometimes the suitable welding product for a dis-

similar joint is not evident. Potential electrodes and

filler metals must be evaluated on the basis of their

ability to accept dilution from the two base metals

without the resulting weld being crack sensitive or

unsuitable in some other way. For a weld between a

nickel-base alloy and another material, the best

results will usually be obtained with a high nickel

alloy welding product.

2) Dilution Rates

Dilution rate resulting from a set of welding condi-

tions (welding process, technique, joint design, etc.)

can be accurately determined by chemical analysis of

a deposited bead. The dilution rate can also be deter-

mined by an area comparison on a joint cross section.

As shown in Figure 17, the rate is calculated from

measurements of the final weld-metal area and the

area of original base metal included in it.

Dilution rates for shielded metal-arc welding are

well established. Also, welder technique has less effect

on dilution rate with shielded metal-arc welding than

with other welding processes. For flat-position shield-

ed metal-arc welding, a dilution rate of 30% is typical

and may be used to calculate weld deposit composi-

tion. A 30% dilution rate means that 70% of the com-

plete weld bead is supplied by the electrode, and 30%

is supplied by the base metals with 15% coming from

each dissimilar member. For other welding processes,

dilution rates are dependent upon the specific welding

technique and can vary widely. Dilution rates with the

gas-metal arc process usually range from as little as

10% to over 50%, depending upon the type of metal

(a) Processes marked X are recommended.

(b) Fine grain is smaller than ASTM Number 5,

coarse grain ASTM Number 5 or larger.

Table 16 - Effect of Grain Size on

Recommended Welding Processesa

Gas Gas Shielded

Alloy Grain Metal ElectronTungsten Metal

SizebArccBeam Arc Arc

INCONEL alloy 600 Fine X X X X

Coarse – – X X

INCONEL alloy 617 Fine X X X X

Coarse – – – X

INCONEL alloy 625 Fine X X X X

Coarse – – X X

INCONEL alloy 706 Fine – X X X

Coarse – – – X

INCONEL alloy 718 Fine – X X X

Coarse – – – X

INCOLOY alloy 800 Fine X X X X

Coarse – X X X

AISI Type 316 Fine – – X X

Coarse – – X X

AISI Type 347 Fine X X X X

Coarse – – X X

Figure 17. Calculation of dilution rate from cross-sectional

area of weld bead.

Base Metal Dilution =

A + B

Weld Metal

Figure 18. Weld metal contributed by each source in a dissim-

ilar weld.

MONEL alloy 400 304 Stainless Steel

70%

15%15%

Figure 19. Multiple-pass dissimilar weld. Bead 1 is 15% A,

15% B, 70% filler metal. Bead 2 is 15% A, 15% Bead 1, 70% filler

metal. Bead 4 is 15% Bead 2, 15% Bead 3, 70% filler metal.

transfer and torch manipulation. The highest dilution

rates are encountered with spray transfer and the low-

est with short-circuiting transfer. Large variations in

dilution rate are also found with the gas tungsten-arc

process. Dilution rates can range from about 20% to

over 80% depending on the technique and the amount

of filler metal added. The dilution rate in a joint

between MONEL alloy 400 (67% Ni, 32% Cu) and

Type 304 stainless steel (8% Ni, 18% Cr, 74% Fe) made

with INCO-WELD A Electrode (70% Ni, 15% Cr, 8%

Fe) would be composed of 15% MONEL alloy 400, 15%

Type 304 stainless steel, and 70% INCO-WELD A

Electrode. Figure 18 shows the relative amounts of

each material in the weld bead. The amount of major

elements contributed by each source can be calculated

as follows:

Contribution of INCO-WELD A Electrode:

70% x 70% Ni = 49% Nickel

70% x 15% Cr = 10.5% Chromium

70% x 8% Fe = 5.6% Iron

Dilution by MONEL alloy 400:

15% x 67% Ni = 10% Nickel Dilution

15% x 32% Cu = 4.8% Copper Dilution

Dilution by Type 304 stainless steel:

15% x 8% Ni = 1.2% Nickel Dilution

15% x 18% Cr = 2.7% Chromium Dilution

15% x 74% Fe = 11.1% Iron Dilution

The electrode contribution added to base-metal dilu-

tion is the calculated composition of the weld deposit:

60.2% nickel (49% + 10% + 1.2%), 13.2% chromium

(10.5% + 2.7%), 16.7% iron (5.6% + 11.1%), and 4.8%

copper.

In a multiple-pass weld, composition remains con-

stant along each bead in a macro or bulk sense but

varies with bead location. The root bead is diluted

equally by the two base metals. As shown in Figure 19,

subsequent beads may be diluted partially by a base

metal and partially by previous bead or entirely by

previous beads.

3) Dilution Limits

Once the potential chemical composition of dissimilar

weldment is determined, it becomes necessary to

determine whether that composition is acceptable.

This can in general be done by use of the following

dilution limits. It is to be noted that these values are

general in nature and no warranty is made as to their

absolute accuracy. Also, the cracking tendency of a

weld will also be influenced by its configuration, size,

residual stresses, the welding process being used, etc.

The elements normally of concern in considering

dilution of nickel alloy welding products are copper,

chromium, and iron. All of the products can accept

unlimited dilution by nickel without detriment.

Dilution limits given in the following discussion

apply only to solid solution weld metal and wrought

base materials. The values should be considered as

guidelines. Questionable cases may require that a trial

joint be evaluated. When a weld metal will be diluted

by more than one potentially detrimental element

(e.g., Pb, Sn, or Zn), allowance should be made for pos-

sible additive or interactive affects.

Nickel Welding Products.

Nickel Welding Electrode 141 and Nickel Filler Metal

61 have high solubility limits for a variety of elements,

and, from the standpoint of dilution tolerance, they are

excellent dissimilar-welding materials. Use of the

products for dissimilar welding, however, is often lim-

ited by their lower strength, in comparison with other

nickel-alloy welding products.

The following dilution limits do not apply to NI-

ROD and NI-ROD 55 Welding Electrodes. Those elec-

trodes are specifically formulated for the welding of

cast iron.

The nickel welding products have complete solubil-

ity for copper and can accept unlimited dilution by

that element.

Chromium dilution of Filler Metal 61 and Welding

Electrode 141 should not exceed 30%.

Nickel Welding Electrode 141 can tolerate up to

about 40% iron dilution. Filler Metal 61, however,

should not be diluted with more than 25% iron.

MONEL (Ni-Cu & Cu-Ni) Welding Products.

The nickel-copper and copper-nickel welding products

(MONEL Welding Electrodes 190 and 187, MONEL

Filler Metals 60 and 67) can tolerate unlimited dilu-

tion by copper.

Nickel-copper weld deposits can be diluted with up

to about 8% chromium.

Copper-nickel deposits (Filler Metal 67 and Welding

Electrode 187) should not be diluted with more than

5% chromium.

Iron dilution limits for deposits of MONEL Filler

Metal 60 are influenced by the welding process used.

If the deposit is applied by submerged-arc welding, it

can tolerate up to about 22% iron dilution. With a gas-

shielded process, the deposit can only be diluted by up

to 15% iron without loss of mechanical properties.

If a joint involving steel is to be welded by a gas-

shielded process with Filler Metal 60, a barrier layer

of Nickel Filler Metal 61 should first be applied to the

steel. Shielded metal-arc deposits of MONEL Welding

Electrode 190 can be diluted with up to about 30%

iron.

Iron dilution of copper-nickel weld deposits

(MONEL Filler Metal 67 and Welding Electrode 187)

should not exceed 5%.

INCONEL (Ni-Cr, Ni-Cr-Mo, Ni-Cr-Co-Mo)

Welding Products.

The INCONEL nickel-chromium welding products are

the most widely used materials for dissimilar welding.

The products produce high-strength weld deposits,

and the deposits can be diluted by a variety of dissim-

ilar materials with no reduction of mechanical proper-

ties. Included in the nickel-chromium group of welding

products is INCO-WELD A Electrode, which has

exceptional dissimilar-welding capability.

Copper dilution of INCONEL welding products

should not exceed about 15%.

The maximum total chromium content in the com-

pleted weld can be up to 30%. Since the welding prod-

ucts contain 15-20% chromium, dilution by chromium

must be kept below 15%.

SMAW deposits of nickel-chromium from flux coat-

ed electrodes can accept up to about 50% iron dilution.

Iron dilution of nickel-chromium filler metals, howev-

er, should not exceed 25%.

Silicon dilution of nickel-chromium deposits should

also be considered, especially if the joint involves a

cast material. Total silicon content in the weld deposit

should not exceed about 0.75%.

4) Dissimilar Welding Products.

Environmental requirements of some welds will

necessitate that they be deposited with non-matching

weld metal. Iron castings are usually welded with

nickel and nickel-iron (NI-ROD and NI-ROD 55) weld-

ing electrodes for strength, ductility, machinability,

and other properties of interest. Nickel steels for cryo-

genic service (e.g. 9% Ni steel for liquid natural gas

service) are often welded with INCONEL welding

products because of their tensile strength and tough-

ness at low temperatures. MONEL alloy 400 for serv-

ice in hot saline is welded with INCONEL Welding

Electrode 112 and INCONEL Filler Metal 625 to avoid

preferential attack of the welds due to galvanic corro-

sion of the welds.

Super-Austenitic Stainless Steels (typically, Fe-25%

Ni-20% Cr-6% Mo-0.2% N) are usually welded with

INCONEL Welding Electrodes 112 and 122,

INCONEL Filler Metals 625 and 622 or products that

contain higher molybdenum contents. This is to pro-

vide welds that exhibit corrosion resistance equal to or

better than the base metal. Over-alloyed welds are

needed to offset the elemental segregation that occurs

during solidification of the weld. These examples are

by no means exhaustive but are intended to illustrate

the versatility of nickel alloy weld metals in solving

specific weld metal requirements in dissimilar metals

welding applications.

Some general guidelines for selection of welding

products for dissimilar joining applications are found

in Table 17.

5) Thermal Expansion and Melting Point

In addition to weld-metal dilution, differences in ther-

mal expansion and melting point can influence the

selection of filler metal for dissimilar joints, especially

when the welded parts will be exposed to high service

temperatures.

Expansion differences in pieces to be joined can

result in significant stresses in the joint area and a

resulting reduction in fatigue strength. If one of the

base metals is of lower strength, a filler metal that has

an expansion rate near that of the weaker base metal

should be selected. The stress resulting from unequal

expansion will then be concentrated on the stronger

side of the joint.

Joining pieces of austenitic stainless steel and mild

steel illustrates the importance of thermal expansion

considerations. The expansion rate of mild steel is

lower than that of stainless steel. From the stand-

point of dilution, either a stainless-steel electrode or

an INCONEL nickel-chromium welding product

would be suitable. The stainless electrode has an

expansion rate near that of wrought stainless steel.

Thus, if the joint is welded with a stainless steel

product, both the weld metal and the stainless base

metal expand in a similar manner to concentrate

stresses along the weaker (mild-steel) side of the

joint. If the joint is welded with an INCONEL

welding product, the stress resulting from unequal

expansion will be confined to the stronger, stainless

steel side of the joint. An example of this principle is

dissimilar joints in power generation boiler tubes.

T-11 (1.25% Cr-0.5% Mo) and T-22 (2.25% Cr-1% Mo)

waterwall tubes are welded to 304 stainless steel

superheater tubes. Welds made with INCO-WELD A

Welding Electrode or INCONEL Filler Metal 82 pro-

vide service life 5-7 times that of 309 stainless steel

weldments.

Differences in melting point between two base met-

als or between the weld metal and base metal can dur-

ing welding result in rupture of the material having

the lower melting point. Solidification and contraction

of the material with the higher melting point focuses

stresses on the lower melting point material while it is

in a weak, incompletely solidified condition. The prob-

lem can often be eliminated by the application of a

layer of weld metal on the low-melting-point base

metal before the joint is welded. Thus, a lower stress

level is present during application of the weld-metal

layer. During completion of the joint, the previously

applied weld metal serves to reduce the melting-point

differential across the weld joint.

Carbon migration can be an important considera-

tion in the selection of a filler metal for a dissimilar

joint with carbon steel. Nickel-alloy weld metals are

effective barriers to carbon migration. For example, in

joining carbon steels to stainless steels, high-nickel

weld materials are sometimes used to prevent unde-

sirable carbon migration from the carbon steel into the

stainless steel where it might cause sensitization by

combining with chromium and weakening of the

depleted carbon steel.

Welding Product Selection

The selection of the optimum welding product is

essential to the success of a joining application. In

addition to the alloys being joined, many factors

including strength, corrosion resistance, physical and

mechanical properties, and anticipated weld metal

dilution must be considered. However, as a general

rule it is best to select a welding product that produces

a weldment with strength and corrosion resistance

superior to that of the material (or materials) being

joined.

It is acknowledged that this is a complex subject

requiring a thorough evaluation of the required prop-

erties of the joint. However, some general guidelines

are presented in Table 17 (page 30 & 31) to assist the

welding engineer. Designers may also wish to contact

Special Metals Welding Products Company in Newton,

NC for consultation and visit the website at

www.specialmetalswelding.com.

Corrosion Resistance

The welding process and procedure and choice of weld-

ing product can greatly affect the corrosion resistance

of the component being fabricated. Thus, the welding

engineer must be cognizant of these effects and design

accordingly. In general, it is best to join materials with

over-matching composition (more highly alloyed, more

corrosion-resistant) welding products. A comprehen-

sive discussion of corrosion mechanisms is found in

publication number SMC-026, “Special Metals: High-

Performance Alloys for Resistance to Aqueous

Corrosion”.

Aqueous corrosion takes place as a flow of electric

current between an anode and a cathode. Corrosion

occurs at the anode. The relative sizes of the anode

and the cathode can significantly affect the corrosion

rate. If the cathode is significantly larger than the

anode, the rate can be significantly increased. Thus,

when designing a welded structure it is best that the

weld metal be cathodic to the base metal. In other

words, the weld should be more corrosion-resistant

than the base metal. Since the weld is generally much

smaller in area than the base metal, were the weld to

be anodic, disastrous consequences could result. For

example, the weld could simply corrode away prefer-

entially to the base metal. As an example, for service

in a marine environment, INCOLOY alloy 825 is best

joined with INCONEL alloy 625 welding products -

INCONEL Welding Electrode 112 or Filler Metal 625.

Or, for service in flue gas desulfurization systems,

INCONEL alloy C-276 is joined with INCO-WELD

686CPT welding products.

The idea of using over-matching composition

welding products is particularly important when

joining nickel-chromium-molybdenum corrosion-resis-

tant alloys. Elements with relatively high melting

points (e.g. molybdenum and tungsten) tend to segre-

gate. Welding products with over-matching composi-

tion are often chosen for welding corrosion-resistant

alloys. For example, 316 and 317 grades of stainless

steel, 6% molybdenum super-austenitic stainless

steels, duplex stainless steels, INCOLOY alloy 825,

and INCONEL alloy G-3 are often joined with

INCONEL alloy 625 welding products - INCONEL

Welding Electrode 112 and INCONEL Filler Metal

625. More highly alloyed corrosion-resistant materi-

als such as INCONEL alloys 625, 622, and C-276 are

welded with the INCONEL alloy 686 welding prod-

ucts, INCO-WELD 686CPT Welding Electrode and

Filler Metal. More information on the use of INCO-

WELD 686CPT products for over-matching welding is

included in publication SMC-024, “INCONEL alloy

686”, on our website, www.specialmetals.com.

Welding Precipitation –

Hardenable Alloys

The ability of precipitation-hardenable alloys to be

strengthened by heat treatment results from their com-

plex chemical composition and intricate metallurgical

reactions that must take place in a very exact manner.

Thus joining such alloys must be done exactly accord-

ing to complex welding and heat treating procedures.

The precipitation-hardenable alloys produced by

SMC are strengthened by two hardening systems.

One is the nickel-aluminum-titanium system, which

includes DURANICKEL alloy 301, MONEL alloy K-

500, and INCONEL alloy X-750. The other is the

nickel-niobium (columbium)-aluminum-titanium sys-

tem, which includes INCONEL alloys 706, 718 and

725.

Figure 20. Failure in INCONEL alloy X-750 induced by resid-

ual welding stress at a 2-in. (51-mm) thick joint which was

welded in the age-hardened condition and re-aged at 1300ÞF

(705ÞC) for 20 h after welding.

NNiicckkeell

220000

MMOONNEELL

aallllooyy

440000

IINNCCOONNEELL

aallllooyy

660000

IINNCCOONNEELL

aallllooyy

662255

IINNCCOONNEELL

aallllooyy

668866

IINNCCOOLLOOYY

aallllooyyss

880000,,

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&& SSuuppeerr

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&& NNiicckkeell

SStteeeellss

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CChhrroommiiuumm

SStteeeellss

AAuusstteenniittiicc

SSttaaiinnlleessss

SStteeeellss

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MMOONNEELLIINNCCOONNEELL IINNCCOONNEELLIINNCCOONNEELL 880000HH//HHTT aanndd

NNiicckkeell 220000 aallllooyy 440000aallllooyy 660000 aallllooyy 662255aallllooyy 668866 880000

Nickel 61 MONEL 60 INCONEL 82 INCONEL 625 I-W 686CPT INCONEL 82

Nickel 61 Nickel 61 INCONEL 82 INCONEL 622 Nickel 61

Nickel 61 INCONEL 82

Nickel 141 Nickel 61

MONEL 190 MONEL 60 INCONEL 625 INCONEL 625 I-W 686CPT INCONEL 625

Nickel 141 INCONEL 625 INCONEL 82 INCONEL 82 INCONEL 625 INCONEL 82

INCONEL 112 Nickel 61 INCONEL 82

MONEL 190 INCONEL 622

INCO-WELD A INCO-WELD A INCONEL 82 INCONEL 625 I-W 686CPT INCONEL 617

INCONEL 112 INCONEL 112 INCONEL 82 INCONEL 625 INCONEL 625

INCONEL 182 INCONEL 182 INCO-WELD A INCONEL 82

Nickel 141 INCONEL 182 INCONEL 622

INCO-WELD A INCO-WELD A INCO-WELD A INCONEL 625 I-W 686CPT INCONEL 617

INCONEL 112 INCONEL 112 INCONEL 112 INCONEL 62 INCONEL 625

INCONEL 182 Nickel 141 INCONEL 182 INCONEL 622 INCONEL 82

Nickel 141 INCONEL 112

INCO-WELD A I-W 686CPT INCO-WELD A I-W 686CPT I-W 686 CPT I-W 686CPT

I-W 686CPT INCO-WELD A INCONEL 82 INCONEL 112 INCONEL 622 INCONEL 617

Nickel 141 INCONEL 112 I-W 686CPT INCONEL 625

I-W 686CPT INCONEL 82

INCO-WELD A INCO-WELD A INCO-WELD A INCO-WELD A INCO-WELD A INCONEL 617

INCONEL 112 INCONEL 112 INCONEL 112 INCONEL 112 I-W 686CPT INCONEL 82

INCONEL 182 INCONEL 182 INCONEL 117 INCONEL 117 INCONEL 122 INCO-WELD A

Nickel 141 INCONEL 182 INCONEL 117

INCO-WELD A INCO-WELD A INCO-WELD A INCONEL 112 I-W 686CPT INCO-WELD A

Nickel 141 INCONEL 112 INCONEL 112 INCONEL 122 INCONEL 112 INCONEL 112

INCONEL 182 INCONEL 182 I-W 686CPT INCONEL 122

INCO-WELD A INCO-WELD A INCO-WELD A INCONEL 112 INCO-WELD A INCO-WELD A

INCONEL 112 INCONEL 112 INCONEL 112 INCO-WELD A I-W 686CPT INCONEL 117

INCONEL 182 INCONEL 182 INCONEL 182 INCONEL 122

Nickel 141 MONEL 190 INCONEL 182

INCO-WELD A INCO-WELD A INCO-WELD A INCONEL 112 INCO-WELD A INCO-WELD A

INCONEL 112 INCONEL 112 INCONEL 112 INCO-WELD A I-W 686CPT INCONEL 117

INCONEL 182 INCONEL 182 INCONEL 117 INCONEL 122

Nickel 141 INCONEL 182

INCO-WELD A INCO-WELD A INCO-WELD A I-W 686CPT INCO-WELD A INCO-WELD A

INCONEL 112 INCONEL 112 INCONEL 112 INCONEL 112 I-W 686CPT INCONEL 112

INCONEL 182 INCONEL 182 INCONEL 117 INCONEL 122 INCONEL 117

Nickel 141 MONEL 190 INCONEL 182 INCONEL 182

I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT

INCO-WELD A INCO-WELD A INCO-WELD A INCONEL 112 INCONEL 122 INCO-WELD A

Nickel 141 INCONEL 122 INCONEL 122 INCONEL 122 INCONEL 122

INCONEL 122

INCO-WELD A INCO-WELD A INCO-WELD A INCO-WELD A I-W 686CPT INCO-WELD A

INCONEL 112 INCONEL 112 INCONEL 117 INCONEL 117 INCONEL 117 INCONEL 117

INCONEL 182 INCONEL 182 INCONEL 122

Nickel 141 MONEL 190

MONEL 187 MONEL 187 INCO-WELD A INCO-WELD A I-W 686CPT INCO-WELD A

MONEL 190 MONEL 190 INCONEL 182 INCONEL 112 Nickel 141 INCONEL 182

Nickel 141 Nickel 141 Nickel 141 Nickel 141 INCONEL 122 Nickel 141

TTaabbllee 1177 -- SSuuggggeesstteedd NNiicckkeell AAllllooyy WWeellddiinngg PPrroodduuccttss

FFiilllleerr MMeettaallss ffoorr GGMMAAWW,, GGTTAAWW,, &&

SSAAWW ((aabboovvee hhiigghhlliigghhtteedd ddiiaaggoonnaall))

CCaarrbboonn,,DDuupplleexx aanndd

IINNCCOOLLOOYY LLooww aallllooyy 33 -- 3300%%AAuusstteenniittiiccSSuuppeerr DDuupplleexx CCaasstt hhiigghh-- CCooppppeerr--

aallllooyy 882255&& NNiicckkeell CChhrroommiiuumm SSttaaiinnlleessss SSttaaiinnlleessss tteemmppeerraattuurree NNiicckkeell

SStteeeellss SStteeeellssSStteeeellss SStteeeellss aallllooyyss aallllooyyss

INCONEL 625 INCONEL 82 INCONEL 82 INCONEL 82 I-W 686CPT INCONEL 82 MONEL 60

INCONEL 82 Nickel 61 Nickel 61 Nickel 61 INCONEL 82 Nickel 61 MONEL 67

Nickel 61 Nickel 61 Nickel 61

INCONEL 622

INCONEL 625 INCONEL 625 INCONEL 625 INCONEL 625 I-W 686CPT INCONEL 625 MONEL 60

INCONEL 82 INCONEL 82 INCONEL 82 INCONEL 82 INCONEL 625 INCONEL 82 MONEL 67

MONEL 60 MONEL 60 INCONEL 82 Nickel 61

INCONEL 622

INCONEL 625 INCONEL 625 INCONEL 625 INCONEL 617 I-W 686CPT INCONEL 617 INCONEL 82

INCONEL 82 INCONEL 82 INCONEL 82 INCONEL 625 INCONEL 82 INCONEL 625 Nickel 61

INCONEL 82 INCONEL 622 INCONEL 82

INCONEL 625 INCONEL 625 I-W 686CPT I-W 686CPT I-W 686CPT INCONEL 617 INCONEL 625

INCONEL 82 INCONEL 625 INCONEL 625 INCONEL 622 INCONEL 625 INCONEL 82

INCONEL 82 INCONEL 82 INCONEL 82 Nickel 61

I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT

INCONEL 625 INCONEL 625 INCONEL 625 INCONEL 625 INCONEL 617 INCONEL 625

INCONEL 82 INCONEL 82 INCONEL 82 INCONEL 82 Nickel 61

INCONEL 625 INCONEL 625 INCONEL 625 INCONEL 617 I-W 686CPT INCONEL 617 INCONEL 82

INCONEL 82 INCONEL 82 INCONEL 82 INCONEL 625 INCONEL 82 INCONEL 625 Nickel 61

INCONEL 82 INCONEL 622 INCONEL 82

INCONEL 625 INCONEL 625 INCONEL 625 INCONEL 625 I-W 686CPT INCONEL 625 INCONEL 82

I-W 686CPT INCONEL 82 INCONEL 82 INCONEL 82 INCONEL 625 INCONEL 82 Nickel 61

INCONEL 112 INCONEL 622

I-W 686CPT

INCO-WELD A INCONEL 625 INCONEL 625 INCONEL 625 I-W 686CPT INCONEL 625 INCONEL 82

INCONEL 112 INCONEL 82 INCONEL 82 INCONEL 82 INCONEL 82 INCONEL 82 Nickel 61

INCONEL 182 INCO-WELD A INCONEL 622

INCONEL 112

INCO-WELD A INCO-WELD A INCONEL 625/52 INCONEL 625 I-W 686CPT INCONEL 625 INCONEL 82

INCONEL 112 INCO-WELD 112 INCONEL 82 INCONEL 82 INCONEL 625 INCONEL 82 Nickel 61

INCONEL 182 INCONEL 82 INCONEL 82 INCONEL 617

INCONEL 112/152 INCONEL 622

INCO-WELD A INCO-WELD A INCO-WELD A I-W 686CPT I-W 686CPT INCONEL 82 INCONEL 82

INCONEL 112 INCONEL 112 INCONEL 112 INCONEL 82/625 INCONEL 82 Nickel 61

INCONEL 182 INCONEL 182 INCONEL 182 I-W A/686CPT INCONEL 622

INCONEL 112

I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT I-W 686CPT

INCONEL 112 INCO-WELD A INCO-WELD A INCO-WELD A INCONEL 622 INCONEL 82 INCONEL 82

INCONEL 122 INCONEL 122 INCONEL 122 INCONEL 122 INCONEL 122 INCONEL 622 INCONEL 622

INCONEL 182 I-W 686CPT

INCO-WELD A INCO-WELD A INCO-WELD A INCO-WELD A I-W 686CPT INCONEL 617 INCONEL 82

INCONEL 112 INCONEL 112 INCONEL 112 INCONEL 112 INCO-WELD A INCONEL 82 Nickel 61

INCONEL 182 INCONEL 117 INCONEL 117 INCONEL 122 INCO-WELD A

INCONEL 117

INCO-WELD A INCO-WELD A INCO-WELD A INCO-WELD A I-W 686CPT INCO-WELD A MONEL 67

INCONEL 182 INCONEL 182 INCONEL 182 INCONEL 182 INCO-WELD A INCONEL 182

Nickel 141 MONEL 190 Nickel 141 Nickel 141 INCONEL 122 Nickel 141

Nickel 141 MONEL 187

WWeellddiinngg EElleeccttrrooddeess ffoorr SSMMAAWW

((bbeellooww hhiigghhlliigghhtteedd ddiiaaggoonnaall))

Both types of alloy systems are weldable. The most

significant difference between the two systems is the

rate at which precipitation occurs. Precipitation of the

strengthening constituents in aluminum-titanium-

niobium hardened alloys occurs more slowly. The

delayed precipitation reaction enables the alloys to be

welded and directly aged with less possibility of crack-

ing.

Cracking can occur when high residual welding

stresses are present during the aging treatment as

shown in Figure 20. Cracking takes place in the base

metal near the heat-affected zone, the area of highest

stress. Stress relief occurs very slowly at aging tem-

peratures. Thus, high residual welding stresses in

conjunction with stresses resulting from aging can

exceed the rupture strength of the base metal and the

material cracks.

Precipitation-hardenable alloys are best joined by

processes which induce the least stresses in the weld-

ment. The gas tungsten-arc welding process is gener-

ally preferred. Ideally, matching composition welding

products are used. If similar composition products are

not available, a welding product of an alloy with prop-

erties similar to the alloy is used. When a dissimilar

welding product must be used, it is critical that a prod-

uct with similar aging constituents be chosen.

GENERAL WELDING PROCEDURES

Heat input during welding should be kept as low as

practical. For multiple-bead or multiple-layer welds,

several small beads should be used instead of a few

large, heavy beads.

Aluminum and titanium readily form high melt-

ing oxide compounds. Even under ideal welding

conditions, aluminum and titanium oxides form and

float to the top of the molten weld puddle. When

depositing multiple pass weldments, the oxide particle

can accumulate to the point that a scale is

formed. The oxide scale can inhibit proper fusion.

Also, flakes of the oxide scale can become entrapped

in the weldment. The trapped oxide particles can

act as mechanical stress raisers and significantly

reduce joint efficiency and service life. The oxide

film should be removed by abrasive blasting or

grinding when it becomes heavy enough to be visu-

ally apparent on the weld surface. Wire brushing

is not recommended for this purpose as it does not

actually remove the oxide film but only polishes it,

thus hiding it from sight.

Rigid or complex structures must be assembled and

welded with care to avoid excessively high stress lev-

els. Fabricated parts or subassemblies should be given

sufficient annealing treatments to ensure a low level

of residual stress before they are precipitation heat

treated. Any part that has been significantly worked

by bending, drawing or other forming operations

should be annealed prior to welding. Heat treating

should be done in furnaces with an atmosphere con-

trolled to limit oxidation and, thus, minimize subse-

quent cleaning operations. If a thermal treatment has

been performed on material containing partially filled

weld grooves, the oxide should be removed from the

welding area by grinding or abrasive blasting before

welding is resumed.

ALUMINUM-TITANIUM

HARDENING SYSTEM

Because of their rapid aging response, alloys hardened

by the aluminum-titanium precipitation reaction

are susceptible to weld-associated base-metal cracking

when they are welded and aged. Thus, special atten-

tion is required when preparing a welding/heat treat-

ing procedure.

Welding of aluminum-titanium hardened alloys is

best accomplished after the component has been

annealed or solution annealed prior to welding.

Components welded in the aged condition should not

be subsequently heat treated or exposed to service

temperatures in the aging range (>1000°F).

Weldments age hardenable by the aluminum-tita-

nium reaction should be solution-treated prior to

precipitation heat treating. It is important that the

thermal treatment be carried out with a fast, uni-

form rate of heating to avoid prolonged exposure to

temperatures in the precipitation-hardening range.

The best method to attain this high heating rate is

to charge the weldment directly into a furnace pre-

heated to the appropriate temperature. If the mass

of the part is large in relation to furnace area, it

may be necessary to preheat the furnace to 200-

500°F (110-280°C) above the annealing temperature.

It is sometimes impractical to anneal a part

after welding. Preweld heat treatments may be help-

ful in such cases. Two procedures that have been

used successfully for INCONEL alloy X-750 are:

Heat at 1550°F (845°C)/16 hrs., air-cool, and

weld, or

Heat at 1950°F (1065°C) 1 hr., furnace-cool

at a rate of 25-100°F (15-55°C)/h to 1200°F

(650°C),air-cool and weld.

ALUMINUM-TITANIUM-NIOBIUM

(COLUMBIUM) HARDENING SYSTEM

The addition of niobium (columbium) to the alu-

minum-titanium reduces the rate of the precipitation

reaction. This reduces the tendency of the alloy to

cracking during heat treatment.

Aluminum-titanium-niobium hardened alloys such

as INCONEL alloys 706, 718, and 725 are best welded

in the annealed or solution-treated condition. If com-

plex units must be annealed in conjunction with weld-

ing or forming operations, the annealing temperature

should be consistent with the specification and end-use

requirements. The alloys have good resistance to post-

weld cracking. Pierce-Miller weld-patch tests

have shown that annealed alloy 718 sheet can under

some conditions be welded and directly aged without-

cracking. However, direct aging of highly restrained

Equipment should be designed so that welds are

located where the effects of reduced rupture ductility

will not be detrimental. Generally, this involves

placing the welds in areas where minimum deforma-

tion at high temperatures occurs. For example, a

horizontal pipe supported at its ends and having a

longitudinal weld should be turned to locate the weld

at the top rather than at the bottom. Thus, the elon-

gation that occurs when the pipe sags during high-

temperature service takes place in the wrought por-

tion of the pipe.

To minimize the effects of thermal or mechanical

fatigue, welds should be located in areas of low-

stress concentration. Corners and changes in shape

and dimensions can tend to concentrate stresses.

thus, welds should, when possible, be located

elsewhere. Butt joints are preferred because the

stresses act axially rather than eccentrically as in

corner and lap joints. Figure 21 shows some examples

of design modifications that locate welds in areas of

low stress. Full penetration weldments are best and a

backing weld should be applied when the root side of

the joint is accessible.

Figure 21. Designs for high-temperature service.

Maximum Stress Area

Weld Relocated

Extruded-Wall

Flange

Wrought material

placed in maximum

stress area

Corner Joints

Marginal Design

Butt Joints

Preferred Design

Welded-in Fitting

Maximum Stress Area

Weld Vulnerable

PREFERRED DESIGN

MARGINAL DESIGN

Figure 22. Thermal-fatigue cracking emanating from incom-

plete welds.

sheet that has been welded in the aged condition can

result in base metal cracking. Highly restrained or

complicated structures should be annealed after weld-

ing and prior to age hardening to avoid base metal

cracking. Rapid heating as described above for

aluminum-titanium hardened alloys is also recom-

mended for aluminum-titanium-niobium hardened

alloys as well.

Fabricating Nickel-Alloy

Components for

High Temperature Service

Equipment and components for service at high tem-

peratures are often fabricated from nickel-chromium

and iron-nickel-chromium alloy (e.g., INCONEL alloys

600, 601, and 617 and INCOLOY alloys 800HT and

803) because of their excellent heat resistance. The

severe demands imposed by high temperatures must

be considered in equipment design and welding proce-

dures.

DESIGN FACTORS

Weldments sometimes have lower stress-rupture duc-

tility and/or resistance to thermal fatigue than

wrought products. Proper design of welded structures

can minimize the effects of these reduced properties.

WELDING PROCEDURE

The weld should completely penetrate or close the

joint. Lack of fusion and penetration should be

avoided. Thermal-fatigue failures can often be

traced to incomplete welds that create stress concen-

trations. Figure 22 shows an example. Some joint

designs that facilitate complete penetration are

shown in Figure 23.

If a joint must be located near dimension or shape

changes, careful welding procedures are required to

minimize the inherent stress concentrations. It is

important to avoid undercutting, lack of penetration,

weld craters, and excessive weld reinforcement. If a

joint in rod or bar stock cannot be completely pene-

trated, the weld metal should be continuous and seal

Figure 25. Attack by molten welding flux.

the joint so that none of the process atmosphere can

enter. Figure 24 shows two joint types that can be com-

pletely sealed with weld metal.

Welds of heat treating apparatus fabricated of round

or flat stock should be smoothly flared into the base

metal without undercut. When heat treating equip-

ment is to be exposed to cyclic heating and quenching,

wrap-around or loosely riveted joints are sometimes

desirable as they provide some freedom for movement.

When SMAW or SAW is employed for fabrication of

alloy parts or equipment for high temperature service,

it is essential that all welding slag be removed from

completed joints prior to exposing them to elevated

temperatures. Chromium-bearing nickel alloys exhibit

heat resistance because they form a protective oxide

layer on their surface which prevents corrodents (oxy-

gen, sulfur, carbon, nitrogen, etc.) from penetrating into

the alloy interior. Any slag remaining from welding

becomes molten when exposed to elevated tempera-

tures. The slag reduces the oxide layer on the surface

of the alloy part allowing corrosion to progress quickly

through the alloy section (Figure 25). Many types of

slag contain fluoride and other compounds which are

themselves corrosive and can attack the alloy compo-

nent. Under reducing conditions, the slag can absorb

and concentrate sulfur and other deleterious elements

and compounds and accelerate attack. For example, it

was found that when an alloy component that was con-

taminated with weld slag was exposed in an atmos-

phere containing 0.01% sulfur, the slag which original-

ly contained only 0.05% sulfur was found to contain

1.6% after only a one month exposure. Increased sulfur

content in the slag can also depress its melting temper-

ature, causing it to melt and become corrosive at lower

temperatures.

Testing and Inspection

Nickel alloy welds are normally tested and inspected by

procedures similar to those used for carbon and stain-

less steel welds. Typical inspection techniques include

visual examination, radiography, mechanical testing

(e.g., tensile and impact), and metallography.

Magnetic-particle inspection may be used to inspect

welds in pure nickel products (e.g., Nickel 200 and 201).

However, nickel alloys are non-magnetic under most

conditions so magnetic particle inspection is not possi-

ble. Liquid penetrant inspection is widely used to

locate small surface defects.

BEND TESTING

Bend testing is often used to evaluate the soundness

and ductility of welded joints. Both free and guided

bend tests are used. Specimens may be tested with the

weld oriented either transverse or longitudinal.

Transverse specimens are commonly used for weld

qualification. However, variations in properties across

the weld can yield confusing results leading to the

rejection of acceptable welds. A transverse bend test

specimen contains several distinct zones which may

have quite different properties. This can result in

uneven deformation of the sample during testing. For

example, if the weld metal is somewhat weaker than

the base metal (e.g., as when two pieces of cold worked

material are joined) deformation during bending will

largely take place in the weld. While the weld may be

sound and have excellent ductility, it may rupture dur-

ing bending because of preferential deformation in the

weld as compared to the stronger base metal.

The effect is more pronounced in dissimilar joints in

which one member is lower in strength than the other.

Figure 26 shows a transverse face-bend specimen of a

joint between Nickel 200 and carbon steel. Almost all

elongation took place on the Nickel 200 side of the

joint. Average elongation measured in a gauge length

spanning the entire joint may be 20%. However, the

elongation occurring preferentially on the Nickel 200

side of the joint may be 40% or more.

A longitudinal bend test specimen in which the

weld is in the center and parallel to the long edge

deforms more evenly, thus yielding more reliable test

Figure 23. Designs for achievement of completely penetrated

weld (high-temperature service).

BEVELING

Root

Spacing Spacing

SEPARATION

SIDE BUTT

TEE

Figure 24. Designs for sealed joints by weld-all-around tech-

niques (high-temperature service).

LAP TEE CROSS

OVER

Figure 26. Transverse face-bend specimen. Figure 27. Longitudinal bend-test specimen in which weld

runs central and parallel to the long edge.

TTaabbllee 1188 -- MMaaccrrooeettcchhiinngg SSoolluuttiioonnss ffoorr WWeelldd MMeettaallss

EEttcchhaannttEEttcchhaanntt PPrreeppaarraattiioonn

Nickel Welding Electrode 141 A

Nickel Filler Metal 61 A

MONEL Welding Electrode 187aA

MONEL Welding Electrode 190aA

MONEL Filler Metal 60aA

MONEL Filler Metal 67aA

INCONEL Welding Electrode 112 C

INCONEL Welding Electrode 132 A or B

INCONEL Welding Electrode 182 A or B

INCO-WELD A Electrode A or B

INCONEL Filler Metal 62 A or B

INCONEL Filler Metal 82 A or B

INCONEL Filler Metal 92 A or B

INCONEL Filler Metal 601 A or B

INCONEL Filler Metal 625 C

INCONEL Filler Metal 718aB

INCOLOY Welding Electrode 135 A or B

INCOLOY Filler Metal 65 A or B

WWeelldd MMeettaall

Etchant A

1 part H2O2(30%)

2 parts HCI

3 parts H2O

Must be freshly mixed. Use hot H2O to

speed reaction. Immerse specimen

30-120 sec.

Etchant B (Lepito’s Solution)

1. Dissolve 15 gm (NH4)2SO4in 75 cc of H2O

2. Dissolve 250 gm FeCI3in 100 cc of HCI

3. Mix 1 and 2 and add 30 cc of

HNO3(concentrated). Swab on specimen.

Heat specimen to speed reaction.

Etchant C

1 part H2O2(30%)

4 parts HCI

Must be freshly mixed. Heat specimen to

speed reaction. Immerse specimen 30-120 sec.

(a) Heat specimen to 200ÞF (95ÞC) before etching.

results. As shown in Figure 27, all areas of the joint

must elongate at the same rate regardless of differ-

ences in strength. While they require a greater

amount of welding for preparation of a specimen,

longitudinal bend tests give the inspector a much

more realistic assessment of the quality of a weld-

ment.

Just as the results of transverse bend tests can be

misleading, tensile tests pulled transverse to the

direction of welding can give equally misleading

results for the same reasons. Longitudinal tensile

tests are preferred for determining weld metal

strength and ductility.

VISUAL EXAMINATION

OF ETCHED WELD SPECIMENS

Certainly the most widely used method of weld inspec-

tion is simple visual examination. Visual inspection

can be enhanced by etching the specimen to be exam-

ined to better define details of the weld structure. The

surface of a sample to be etched should be prepared by

grinding. Rough grinding on an abrasive wheel or

emery-cloth belt is usually adequate. Etching solu-

tions for weldments deposited with various welding

products are described in Table 18.

Brazing

Introduction

Brazing is a popular method of joining materials in

which the bond is made without melting of the base

metal. The filler metal wets the base metal by capil-

lary flow. Thus, it is essential that the pieces to be

joined are properly cleaned. They must be free of any

external dirt and significant oxide films or scales

must be removed. Brazing filler metals melt at tem-

peratures below the melting point of the alloys being

joined so the effect of the heat on the properties of the

alloys are minimized. Furnace brazing is particular-

ly popular for joining large numbers of small compo-

nents. When properly designed and produced, the

strength of a brazement approaches that of a weld.

Most nickel and nickel alloy products can be joined

by brazing. General procedural information is pre-

sented here. However, for more detailed information

on procedures and the alloys used as filler metals for

brazing, the reader should contact the brazing filler

metal manufacturer for specific recommendations.

There are many proprietary brazing alloys available

for which information is only available from the man-

ufacturer.

Brazing may be performed manually by heating

with an oxy-fuel torch and by automated means such

as furnace brazing. Brazing is also possible with

high technology heat sources such as LASER.

Four factors are important in achieving high

strength: joint design, close control of joint clear-

ances, elimination of flux inclusions and unfused

areas, and effective wetting of the base material by

the brazing alloy. All these factors must be

addressed in a brazing procedure regardless of the

heat source.

For development of maximum bond strength, the

joint clearance should be small. Another approach

is to make the lap joint three times the thickness

of the thinner member. With this design, slightly

larger clearances and some defects such as flux in-

clusions and incomplete brazed areas can be tolerated.

Parts to be brazed should be designed to be self-

locating. If holding is required, some mechanical

means such as riveting, staking, bolting, or spot weld-

ing should be used.

In all brazing operations, it is essential that the

base material be clean. Common contaminants such

as shop dirt, oil, grease, cutting fluid, marking com-

pounds, etc. may be removed by chemical cleaning

with solvents. Oxide and other surface scales and

films, especially those on age-hardenable alloys (e.g.,

INCONEL alloys 718, 725 and X-750) and other

alloys containing aluminum and/or titanium (e.g.,

INCONEL alloy 601), may require grinding. When

brazing such alloys it may also be helpful to use a

flux to reduce the oxide, plate the parts to be brazed

with nickel or copper prior to brazing, or braze them

in a furnace with a highly reducing atmosphere, or a

vacuum chamber. The information on cleaning and

surface preparation of components for welding pre-

sented earlier in this bulletin pages 2 and 3 is also

applicable to brazing.

Parts which have been brazed must be thoroughly

cleaned before welding (e.g., weld repair of a brazed

part). All brazing alloy must be removed. Contam-

ination of the weld with the braze alloy will almost

certainly cause weld cracking because of the low

melting metals inherent in braze filler metals.

BRAZING ALLOYS

Several different types of braze filler metals may be

used to braze nickel alloys. The choice of the opti-

mum product will be dependent upon economics, the

temperature to which the braze will be exposed, the

alloy being brazed, and the brazing process to be

employed.

Brazing alloys that contain significant levels of

phosphorus (e.g., ASTM BCuP-5) should never be

used with any nickel alloy. The brittle nickel phos-

phide layer that forms at the bond line can fracture

under impact or bending.

Precipitation-hardenable alloys are normally

aged after brazing. Thus, brazing alloys with melting

temperatures above the aging temperatures must be

used.

Stress Cracking

(Liquid Metal Embrittlement)

Before discussing brazing alloys and techniques, it is

first necessary that the reader be warned about a

catastrophic problem that can result from improper

brazing procedures. Caution is advised when brazing

nickel alloys with silver brazing alloys and other

brazing materials containing low melting metals

which can induce base metal cracking (Figure 28).

This phenomenon is a type of stress-corrosion crack-

ing often referred to as liquid metal embrittlement.

It is encountered when brazing high-strength alloys

with annealing temperatures above the melting tem-

perature of the brazing alloy. Cracking occurs

instantaneously at the brazing temperature and is

usually detectable by visual examination.

Liquid metal cracking occurs by the action of a cor-

rosive medium (silver and/or other low melting met-

als in the molten brazing alloy) in conjunction with

Figure 28. Specimen of silver-brazed INCONEL alloy 718

showing stress-corrosion cracking.

stresses in the part being brazed. Both the corrosive

medium and stress must be present for the phenom-

enon to occur. Stresses can be induced by metallur-

gical or mechanical mechanisms. Residual stresses

in precipitation-hardenable alloys can result from

the age hardening heat treatment. Cold forming

(rolling, drawing, bending, spinning, etc.) can produce

enough internal stresses to cause cracking during

brazing. Improper restraint can also create excessive

stresses. Stress can be induced when a fixture does

not provide proper alignment of parts or the parts

are clamped too tightly. When socket joints in tubing

are being brazed, ovality (out-of-roundness) of both

the tube and fitting must be at a minimum.

Otherwise, stress will develop when the tube is

forced into the socket. Unequal, rapid heating can

also cause sufficient stress to cause cracking. If

heavy parts are heated so rapidly that the outside

surfaces become hot without appreciable heating of

the center, thermal stresses can result and stress

cracking may occur.

The precipitation-hardenable alloys must be

brazed only in the annealed condition as the aging

treatment stresses the material. While aged

INCONEL alloy 718 is less sensitive than the other

precipitation-hardenable alloys to stress-corrosion

cracking during brazing, more reliable results will

be obtained by brazing the alloy in the annealed

condition.

Stress-corrosion cracking can usually be eliminat-

ed by a change in procedure, such as:

• Using annealed rather than hard-temper

material.

• Annealing cold-worked parts before

brazing.

• Eliminating externally applied stress.

• Heating at a slower, more uniform rate.

• Using a braze alloy with a higher melt-

ing point. Thus, some stress relief of the

base material occurs during heating before

the brazing alloy melts.

• In torch brazing, heating the fluxed and

assembled parts to a high temperature

(1600°F) and then cooling to the appropri-

ate temperature before applying the braz-

ing alloy.

• Using an alloy not containing silver or

cadmium (Cadmium does not cause

cracking by itself but can aggravate condi-

tions conducive to cracking.)

AAWWSS DDeessiiggnnaattiioonnSSAAEESSoolliidduussaaLLiiqquuiidduussaa

SSiillvveerrCCooppppeerrZZiinnccOOtthheerrss((SSppeecciiffiiccaattiioonn AA55..88))SSppeecciiffiiccaattiioonn((MMeellttiinngg PPooiinntt)),, ÞÞFF((FFllooww PPooiinntt)),, ÞÞFF

15 80 – 5 P BCuP-5 – 1190 1475

35 26 21 18 Cd BAg-2 AMS-4768 1125 1295

40 30 28 2 Ni BAg-4 – 1240 1435

45 15 16 24 Cd BAg-1 AMS-4769 1125 1145

50 15-1/2 16-1/2 18 Cd BAg-1aAMS-4770 1160 1175

50 15-1/2 15-1/2 16 Cd, 3 Ni BAg-3 AMS-4771 1170 1270

60 25 15 – – – 1245 1325

63 28-1/2 – 6 Sn, 2.5 Ni – AMS-4774 1275 1475

72 28 – – BAg-8 – 1435 1435

Silver Brazing

Silver brazing alloys are popular because of their

excellent flow characteristics and ease of usage.

However, their cost is quite high. As noted on the

prior page, silver brazing alloys readily cause liquid

metal embrittlement of stressed alloy components.

Properly made silver braze joints will have the

strength near that of annealed alloys at room-tem-

perature. The strength of silver brazements drops

rapidly as the temperature exceeds 300°F with 400°F

being the maximum service temperature for highly

stressed joints. If design stresses are sufficiently low,

somewhat higher temperatures can be tolerated.

Special alloys are available for service temperatures

up to approximately 750°F.

SILVER BRAZING ALLOYS

Even though their main constituents are copper and

zinc, brazing alloys containing only a small percent-

age of silver carry the silver designation. Examples

are shown in Table 19. There are many silver braz-

ing alloys manufactured under various proprietary

trade names.

ASTM BAg-2, BAg-1, and BAg-1a are low-melting-

temperature materials commonly used with nickel

alloys. Brazing alloys ASTM BAg-4 and BAg-3 will

fill wide clearances and produce large fillets because

they are more viscous and sluggish when molten.

FLUXES

Fluxes for use with silver brazing are mixtures of flu-

orides and borates that melt below the melting tem-

perature of the brazing alloys.

Standard fluxes are used on most alloys not con-

taining aluminum. Special fluxes are available for

aluminum-containing alloys (e.g., MONEL alloy K-

500 and INCONEL alloys 718 and X-750. There are

also fluxes designed to have long life during extend-

ed heating cycles.

Proper safety procedures must be followed during

the preparation or use of fluxes. Fume control is

essential.

JOINT DESIGN

Some of the joint designs commonly used in silver

brazing are shown in Figure 29. Lap joints are pre-

ferred to butt joints. As shown in Figure 29, rings

and washers of brazing alloy are often used. In some

designs, vents must be provided for the escape of air

or steam from the flux. Application of the brazing

alloy should be taken into consideration when parts

are designed.

HEATING METHODS

Any means of heating may be used that will bring the

parts up to brazing temperature in a reasonable

length of time and hold them there long enough for

the alloy to flow. The joint must be uniformly heated.

Torch heating with oxyacetylene, oxy-hydrogen, oxy-

gas, or air-gas is commonly used. A large, soft, reduc-

ing flame will minimize oxidation.

Induction heating is an excellent way to heat a

large number of small parts. Resistance heating is

appropriate for brazing small parts and assembling

small parts to large ones if pressure on the parts can

be tolerated.

Salt bath brazing is feasible but seldom used with

nickel alloys. Metal-bath brazing is used for fine wire

and very small parts.

Electric or oil- or gas-fired furnaces are satisfacto-

ry. Temperature control is important especially

because flow of the brazing alloy cannot be observed.

Surrounding the work with an oxygen-free gas will

help extend the life of the flux during long heating

cycles. Combusted city gas, nitrogen, hydrogen, and

other gases have been used when heating at elevated

temperatures for short times.

ATMOSPHERES

Furnace brazing without flux can be in a vacuum, a

reducing atmosphere of dry hydrogen, dissociated

ammonia, or combusted city gas when proper proce-

dures are followed. Brazing alloys that contain low-

vapor-pressure materials (e.g., cadmium, zinc, lithi-

um) are not suitable for use with vacuum brazing.

A hydrogen atmosphere must be dry for successful

brazing. The dew point required will depend on the

TTaabbllee 1199 -- SSiillvveerr BBrraazziinngg AAllllooyyss

(a) Approximate temperatures, consult manufacturer for exact values.

NNoommiinnaall CCoommppoossiittiioonn,, %%

Figure 29. Some joint designs for silver brazing.

brazing temperature and the composition of the alloy

to be brazed. Figure 30 (page 40) can be used as a

guide in determining the dew point necessary for a

brazing operation. The curves show the temperatures

and dew points at which pure metals are at equilib-

rium with their oxides in hydrogen atmospheres.

Conditions represented by the area above and to the

left of an equilibrium curve are oxidizing to the

metal; conditions below and to the right of a curve

are reducing. For brazing, the dew point must be such

that the atmosphere is reducing to the metal at braz-

ing temperatures.

The plots in Figure 30 are for pure metals. For

alloys, the curve representing the most difficult-to-

reduce element present in an amount over 1% should

be selected as the controlling curve. In practice, the

dew point must be somewhat lower than the indicat-

ed equilibrium point, and a continuous flow of hydro-

gen is required.

PROCEDURE

The flux is generally applied by brush or swab. It is

good practice to apply a generous coating to the parts

prior to assembly and to assemble while the flux is

wet. More flux can be applied to the finished assem-

bly with particular attention paid to coating any pre-

placed brazing alloy. If parts to be heated are covered

by flux, oxidation will be prevented, and there will be

no need for a subsequent oxide-removal treatment.

The flux should be allowed to dry prior to applica-

tion of heat. Heating while the flux is wet often

results in sputtering of the flux as the water is driv-

en off.

When torch heating, the flame is played on the

work prior to applying the brazing alloy so that the

joint area comes up to a uniform temperature of 50°

to 100°F higher than the melting temperature of the

brazing alloy. The brazing alloy will flow to the

hottest area if the parts are properly cleaned.

Care must be taken not to overheat the part.

Overheating, evidenced by a lacy fillet instead of the

shiny appearance of normal molten brazes, is a com-

mon source of trouble as the fluxes break down and

excessive oxidation occurs.

Hand feeding of the brazing alloy is satisfactory

for torch heating. However, since the amount of alloy

used is a matter of operator judgement, it is usually

not as economical as other methods. Brazing alloy

rings, shapes, foil, or powder mixed in flux are gener-

ally more economical methods.

If torch brazing is employed, pre-placed braze

filler metal should not be in the open where it might

be melted prematurely. A neat joint with uniform

filler will not result. Where inspection of the brazed

joint will be difficult (such as the inside of a tube), it

is advisable to place the insert away from the outer

surface. Then a continuous fillet on the outside of the

brazed joint will be a good indication of complete

penetration. If washers or strips of brazing alloy are

used, the parts must be free to move together as the

alloy melts and flows.

When the alloy has flowed completely, the flame

Not Recommended Where

Strength is Important

Force

Better Design

Lap Joint with Minimum Lap

Spud to Tank Design

Flat Side

on Pin

as Vent

Vent Hole

Self Locating Feature

Good Flange Design

Reduced Section

for Better Healing

Use Washer of Alloy

Possible Locations

of Alloy Rings

Possible Locations

of Alloy Rings

Use Only

One

Good Tube to Tube

Sheet Designs

Method of Venting Blind Hole

A Poorly Designed Tubular Joint,

Wasteful of Alloy

and Low in Strength

Well Designed Tubular Joints

should be removed and the joint allowed to cool

undisturbed. A sudden change from a very shiny to a

dull surface appearance indicates solidification.

POSTBRAZING TREATMENT

After brazing, the flux must be removed as it will be

corrosive to some materials. If the parts are

quenched in water from about 700°F, most of the flux

will be broken off by the thermal shock. The balance

will wash off in hot water or steam and water. Flux

residue is soluble in hot water, but considerable soak-

ing time may be required for the removal of thick,

fused material.

If oxidation has occurred, a pickling operation may

be required to clean the assembly. An anodic treat-

ment in 25% sulfuric acid is sometimes helpful for

postbraze cleaning.

Heat treating of precipitation-hardenable alloys is

best performed in two steps:

1. Solution anneal before brazing.

2. Age harden after brazing.

Copper Brazing

Copper brazing is normally used for joining compo-

nents to be used at service temperatures up to 950°F.

-14

500

000

500

000

500

3000

3500

-12

-1

-4

-2

Temperature, F

ew Point

FeO

MoO

ZnO

MnO

CbO

SiO

MgO

TiO

ThO

BaO

BeO

CaO

ZrO

Figure 30. Metal/metal-oxide equilibria in pure hydrogen atmospheres. Metals easier to reduce than those plotted are

Ni, Au, Pt, Ag, Pd, Ir, Cu, Pb, Co, Sn, Os, and Bi. La is more difficult to reduce than those plotted.

At higher temperatures copper brazements exhibit a

drastic loss of strength and oxidize rapidly.

Nickel alloys can normally be copper-brazed with the

same equipment used with steels. Minor changes in

procedure may be necessary due to their spec-

ial characteristics. Brazing temperatures range from

1850° to 2100°F; most operations are done at 2050°F.

A slightly rough or lightly etched surface is pre-

ferred for the optimum flow of copper braze alloys.

Such a surface will be wet with copper for relatively

large distances from actual joints. Polished surfaces

will resist the flow of copper brazing metals.

Elements such as chromium, aluminum, and tita-

nium form refractory oxides in a normal copper

brazing atmosphere. Therefore, such alloys as

INCONEL alloys 718 and X-750 and MONEL alloy

K-500 will be more difficult to braze than Nickel 200

and MONEL alloy 400. To prevent the

formation of these refractory oxides, the parts

may be copper- or nickel-plated prior to brazing.

Before plating, the material should be thoroughly

cleaned and then given an anodic-cathodic strike

treatment in a nickel chloride bath. During the

anodic (reverse current) treatment oxides present

on the material will be removed. The plating may

then be applied with conventional current flow. While

either nickel or copper will help prevent the refracto-

placed as closely adjacent to the joint as possible.

There should be sufficient metal to fill the joint.

Excessive copper braze metal, however, can create exces-

sive alloying with the nickel-chromium base metals.

Depth of alloying (penetration) is a function of

brazing-alloy flow, quantity of brazing alloy, and time

at temperature. When copper flows over the base

metal, it can erode the surface. On heavy sections

this effect may not be significant. However, when

joining thin sections even shallow penetration may

be serious. This problem can be partially overcome

by limiting the amount of brazing alloy and reducing

brazing time.

Excessive oxygen and moisture in the brazing

atmosphere will impede or prevent flow of the copper

brazing alloy. The surface of the part will appear

dark and oxidized rather than bright. A positive

pressure should be maintained in the furnace to pre-

vent air from entering. Improper drying of the com-

bustion gas before it enters the furnace can result in

excessive oxidation.

POST-BRAZING TREATMENT

Copper-brazed parts usually require no post-brazing

treatment. They should appear bright when they are

removed from the furnace. Copper flash can be

removed, either in a bath of 20 parts household

ammonia and 1 part hydrogen peroxide or a solution

of 15 gal. water, 1 gal. sulfuric acid, and 80 lb. of

chromic acid. Immersion time depends on thickness

of copper to be removed. One hour (or more) immer-

sion time may be needed to remove a heavy flash.

Precipitation-hardenable alloys may be heat treat-

ed (age hardened) after brazing.

Flux must be removed from brazed parts by abra-

sive blasting, grinding, or chipping. It’s especially

critical that parts for high-temperature service be

thoroughly cleaned.

Nickel Brazing

Nickel brazing alloys produce joints with strength

and oxidation resistance for service at temperatures

up to 2000°F. While the brazements have good

strength (often approaching that of the base metal),

they generally exhibit only moderate ductility.

ry oxides from forming, but copper will, in addition,

become the brazing alloy. About 0.003 in. of copper is

usually adequate. If desired, the flash may be pickled

off after brazing.

COPPER BRAZING ALLOYS

Commercially pure grades of copper are commonly

used as brazing filler metals. Tough-pitch copper

containing as much as 0.04% oxygen is used.

However, it is generally believed that oxygen-free

copper will produce joints having somewhat greater

strength and ductility.

Alloys may be pre-placed in the form of wire,

strips, slugs, plating, or powder. Powder may be

applied as a slurry. The vehicles or binders most fre-

quently used are methyl cellulose and acrylic resins

whose products of combustion are gases that will not

interfere with the brazing operation. They are pre-

ferred to such binders as machine oil, glycerin, and

varnish, which leave a carbonaceous residue. A fairly

thin mix will be required for dipping, brushing, or

spraying. A stiffer mix may be used in a grease-gun-

like manner.

FLUXES

Fluxes for brazing with copper filler metals are sim-

ilar to those used for oxy-fuel welding. Mixtures of

chloride salts (calcium, sodium, and barium) and flu-

oride salts (barium) in an appropriate binder are

suitable. The addition of hematite and wetting

agents may be required for brazing the age harden-

able alloys. The flux mixture will become glass-like

after cooling and is insoluble in water. Common

methods of removal are abrasive blasting, chipping,

and grinding.

JOINT DESIGN

Joint designs for copper-brazing nickel alloys are

similar to those used for steel. Tolerances for assem-

bly range from a light press fit to 0.002 in. maximum

clearance. Butt-brazed joints will have strengths

approaching those of annealed wrought alloy products.

HEATING METHODS AND ATMOSPHERES

Copper brazing is usually limited to furnace heating

because of the atmosphere requirements. Heating

may be electric, gas, or oil as long as the atmosphere

can be maintained within desired limits. In some spe-

cial cases, other means such as induction or resist-

ance heating can be used, but only for highly special-

ized brazing of relatively small parts.

An atmosphere of combusted gas (containing not

more than 20 grains sulfur per 100 cu ft) is satisfac-

tory for MONEL alloy 400 and Nickel 200 but not

INCONEL alloy 600. Dissociated ammonia can be

used with alloy 400 and Nickel 200 and also for

INCONEL alloy 600 if the dew point is low (-80°F or

lower).

PROCEDURE

Copper brazing materials rapidly alloy with MONEL

alloy 400 and Nickel 200. The braze metal should be

Room Temperature 119,230 134,500

800 100,150 103,230

1200 91,300 94,880

1400 69,250 70,850

1500 – 53,600

1600 41,730 39,280

1700 – 35,100

1800 23,280 23,600

1900 – 18,650

2000 13,790 13,810

TTaabbllee 2200 -- SSttrreennggtthh ooff BBuutttt JJooiinnttss iinn NNiicckkeell--

CChhrroommiiuumm--CCoobbaalltt AAllllooyy SS--559900 ((AAMMSS 55557700)) BBrraazzeedd

wwiitthh NNiicckkeell--CChhrroommiiuumm--BBoorroonn--SSiilliiccoonn BBrraazziinngg AAllllooyy

((AAMMSS 44777755))

TTeesstt TTeemmppeerraattuurree

°°FF

TTeennssiillee SSttrreennggtthh,, ppssii

BBrraazzeedd JJooiinnttBBaassee MMeettaall

SSoolliidduuss,,LLiiqquuiidduuss,,BBrraazziinnggAAWWSSAAMMSS

NNiiCCrrBBSSiiFFeeCCPP°°FF°°FFRRaannggee,, °°FFCCllaassss..SSppeecc..RReemmaarrkkss

73.25 14 3.5 4 4.5 0.75 max – 1790 1900 1950-2200 BNi-1 4775 High strength and heat-resistant joints.

82.4 7 3.1 4.5 3 – – 1780 1830 1850-2150 BNi-2 4777 Similar to BNi-1. Lower brazing tempera

ture.

90.9 – 3.1 4.5 1.5 – – 1800 1900 1850-2150 BNi-3 4778 Good flowing characteristics.

92.5 – 1.5 3.5 1.5 – – 1800 1950 1850-2150 BNi-4 4779 Useful for large, ductile fillets.

70.9 19 – 10.1 – – – 1975 2075 2100-2200 BNi-5 4782 Can be used for nuclear applications.

89 – – – – – 11 1610 1610 1700-1875 BNi-6 – Extremely free flowing.

77 13 – – – – 10 1630 1630 1700-1900 BNi-7 – Useful for heat-resistant joints in thin sec

tions.

70 16.5 3.75 4 4 0.95 – 1740 1950 – – 4575A Good high-temperature corrosion resist

ance.

70 16.5 3.75 4 4 0.6max – 1740 1950 – – 4776 Low-carbon version of 4575A.

TTaabbllee 2211 -- NNiicckkeell--BBaassee BBrraazziinngg AAllllooyyss

NNoommiinnaall CCoommppoossiittiioonn,, %%

Brazing with nickel-base filler metals is particularly

useful for nickel-chromium superalloys such as

INCONEL alloys 718 and X-750 and many of the

NIMONIC and UDIMET alloys. Typical properties

are shown in Table 20.

NICKEL BRAZING ALLOYS

Nickel brazing alloys typically contain 70 to 95%

nickel. Some of these alloys are shown in Table 21.

They are often produced in the form of powder (200

mesh or finer). They are also avail-

able as powder-impregnated sheets that can be cut

or formed into rings, washers, and other shapes.

Powder can be applied directly to the parts to be to

joined by placing it in adjacent holes. More often, it

is applied as a slurry by brushing, spraying, dipping,

or extruding. The slurry should be allowed to thor-

oughly dry before heating. The binder chosen for the

slurry should leave no residue after brazing. Acrylic

resins are flammable but have good characteristics

for this purpose. Water-base methyl cellulose binders

are also satisfactory.

FLUXES

Brazing can be accomplished using protective

fluxes. Fluoride-base fluxes are popular. It is imper-

ative that all residue be removed after brazing

to avoid corrosive attack of the base metal. Flux

residue is generally glass-like and quite tenacious,

requiring grinding, chipping, or abrasive blasting for

removal. Any fluxes that leave residues should not

be used with joints that are inaccessible after assem-

bly. In such cases, fluxes that are highly volatile and

are expended during the brazing cycle are preferred.

JOINT DESIGN

Joint designs with nickel brazing alloys are the same

as those used for silver brazing. Clearance should be

maintained between 0.0005 and 0.005 in.

HEATING METHODS AND ATMOSPHERES

Nickel brazing is often performed in a furnace with

highly reducing atmospheres. Base metals contain-

ing elements that form the most refractory oxides

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(a) More than 0.5%.

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((CCOO22RReemmoovveedd

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AWS Brazing

Atmosphere

Type No.

Copper, Cobalt,

Nickel, Iron

Chromium

Silicon

Titanium

Aluminum

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X X XXXXXX

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require the most stringent atmospheres. For many

applications, dry hydrogen (at least -80°F dew point)

is satisfactory. Table 22 shows suggested guidelines

for atmospheres for use when either the base materi-

al or the brazing alloy contains the listed elements.

However, the choice of atmosphere may be influenced

by other factors in the manufacturing process. Also, if

elements such as lithium are present, they may act

as deoxidizers and permit the use of a less reducing

atmosphere.

Alloys containing aluminum and titanium (e.g.,

precipitation hardenable alloys such as INCONEL

alloy X-750 and 718) require special atmospheres for

successful brazing. Even a dry hydrogen atmosphere

may not be satisfactory for prevention of oxide for-

mation on alloys containing more than 0.5% alu-

minum and/or titanium.

Nickel brazing can also be accomplished in a vac-

uum. A vacuum of at least 0.76 µ Hg is suggested.

After evacuation, the chamber is sometimes back-

filled with dry argon.

Bell-type furnaces are often used for furnace braz-

ing with nickel-base filler metals because of their

ability to satisfy the stringent atmosphere require-

ments. A standard copper-brazing furnace can be

used for nickel-brazing. However, if low dew point

hydrogen is to be used, it may be necessary to use a

special retort to hold the work. Combusted city gas or

dissociated ammonia may be used to surround the

retort and protect the heating elements. There

should be a slight positive pressure in the retort and

it should be well sealed (sand seals containing alu-

mina or mechanical seals, for example). To insure

against an explosion, it should be thoroughly purged

of air.

Oxyacetylene torch brazing can also be accom-

plished with nickel-base braze metals. This is best

accomplished using the powder form of the brazing

alloy mixed with a special high-temperature flux and

a liquid vehicle to form a slurry. The brazing mixture

is then brushed onto the joint.

PROCEDURE

Because it is difficult to obtain wetting on alloys con-

taining more than about 0.5% aluminum and/or tita-

nium, such alloys are often nickel-plated prior to

brazing. The thickness of the plate required is

dependent upon the brazing time and temperature.

In general, however, a plate 0.0005 to 0.0015 inch is

usually sufficient.

Interalloying has a very pronounced effect on the

melting characteristics of the nickel brazing alloys.

At brazing temperatures, the brazing alloy diffuses

into the base metal. As diffusion occurs, the melting

point of the remaining alloy increases. This coupled

with vaporization of volatile elements can result in a

significant increase in the melting temperature of

the brazement. In service it will have useful strength

at temperatures up to and even exceeding the origi-

nal brazing temperature. Interalloying can be some-

what controlled by adjustment of time and tempera-

ture and quantity of brazing alloy.

Brazing

Ni Mn Pd Cr Si Temp, °F Room Temp 1450°F

48 31 21 – – 2060 49,300 22,400

38 – 25 33 4 2150 36,000 31,500

Table 23 - Nickel-Palladium Brazing Alloys

for High-Temperature Applications

Composition, % Shear Strength, psi

Heating the part to be brazed too slowly through

the melting range will cause the lower melting con-

stituents of the alloy to become fluid and flow before

the higher melting point elements. A “skull” of the

higher melting constituents will remain solid. This

material may not melt and flow even at the maxi-

mum brazing temperature. Because only part of the

brazing alloy has been used, incomplete filling may

result. The braze composition will also be altered and

there will be elemental segregation. This undesirable

situation can be avoided, particularly when joining

thin sections, by using a high heating rate and braz-

ing temperature and a shortened brazing time. If the

braze alloy is brought to temperature fast enough, it

will not separate.

POST-BRAZING TREATMENT

If good brazing practices are followed, parts should

emerge from the furnace bright and scale-free, such

that no post-brazing treatment is required.

Precipitation hardenable materials may be heat-

treated in the brazing furnace if desired. If flux has

been used, any residue must be removed.

Other Brazing Alloys

Gold brazing alloys are used in jewelry manufacture

for their color. The base material of gold-filled arti-

cles is often nickel. Procedures used are much like

those for silver brazing. Gold-copper and gold-silver

alloys are sometimes used in electronic vacuum

tubes. Gold-nickel alloys are finding increased use,

particularly in gas turbine and rocket engines.

Nickel and nickel-copper alloys are used as braz-

ing alloys in the electronics industry to join tungsten

and molybdenum to themselves and to other materi-

als. Heating for brazing is generally by induction in a

hydrogen bell.

Palladium-bearing brazing alloys have been devel-

oped for electronic devices and also for some high-

temperature applications. Joining of complex assem-

blies often requires they be brazed without a flux.

Special procedures may be necessary. Palladium

alloys are useful because they have low vapor pres-

sures at operating temperatures and because they

form a series of alloys with graded brazing tempera-

tures so that a number of successive brazing opera-

tions can be carried out on a single assembly..

Nickel-palladium brazing alloys are used for high-

temperature applications. Two of these are shown in

Table 23.

Other alloys for high-temperature brazing contain

gold, silver, platinum, palladium, and manganese.

While they do not produce joints as strong as those

made with nickel-chromium-boron alloys, they are

less prone to interalloying with the base metal.

Thus, they exhibit better flow characteristics without

attacking the base metal.

At elevated temperatures palladium alloy braze-

ments are lower in strength than nickel-chromium

brazements. For example, a nickel-chromium-boron-

silicon brazement deposited using AMS 4775 braze

metal typically exhibits a tensile strength at 1400°F

of about 70 ksi. A brazement of 38% nickel, 33%

chromium, 25% palladium, and 4% silicon has a

tensile strength under similar conditions of about 30

ksi. Such differences in strength must be considered

in the part design.

AWS BAu-4, a brazing alloy of 18% nickel and 82%

gold, can often be used to braze INCONEL alloys

600, X-750, and 718 and other high-temperature

alloys. Some of its desirable characteristics are

resistance to stress corrosion, ability to fill relatively

large clearances, small tendency to erode base metal,

ductility at all temperatures, and good oxidation

resistance. However, the brazements are not as

strong as those made with nickel-chromium-boron-

silicon brazing alloys.

Inspection of Brazements

To verify the quality of brazements, they must be

inspected after deposition. While some inspection

techniques for brazements are similar to those uti-

lized for weld inspection, others are quite different.

All flux residue should be removed before visual

inspection of brazed joints. Pinholes and unbrazed

areas are often easily detected visually. If the braz-

ing alloy has been preplaced so that it must flow com-

pletely through the joint to form a continuous fillet

on the other side, visual inspection is usually suffi-

cient to determine if the joint is sound and leaktight.

However, visual inspection cannot ensure complete

penetration.

A “lumpy” fillet-braze deposit not faired into the

base metal indicates that insufficient heat was used.

Too much heat may result in a fillet with a lacy

appearance and pinholes.

Faulty joints that are clean may be refluxed and

rebrazed. If serious oxidation has occurred, it is best

to remove the braze, clean the joint, and rebraze.

Soldering

Introduction

Soldering may be used to join nickel-base alloys to

themselves and other engineering materials if such

requirements as strength and corrosion resistance

will be met.

SOLDER ALLOYS

Common solders are composed of lead and tin.

Solders with special properties may also contain

antimony, silver, arsenic, bismuth, or indium.

Specifications for solder metals are shown in

ASTM Specification B32.

FLUXES

Selection of the proper flux is an important criterion

in achieving high quality solder joints in nickel and

nickel alloys. Alloys to be soldered should be cleaned

immediately before joining.

Zinc chloride-base fluxes are recommended for

use with Nickel and MONEL alloys in conjunction

with lead-tin or tin-lead solder. They may be pur-

chased or made as shown below.

1. Zinc chloride.......................1 lb.

Ammonium chloride..........1 lb.

Glycerin..............................1 lb.

Water.................................. 1 gal.

2. Neutralized acid (zinc added to hydrochloric

acid until all effervescence stops and an excess

of zinc exists). A small amount of ammonium

chloride may be added.

Rosin-base fluxes can sometimes be used but gen-

erally only under very limited conditions. Special

care is required to qualify the solder procedure to be

sure that the flux is acceptable.

Stronger fluxes are required for nickel-chromium

alloys such as INCONEL alloy 600. The commercial-

ly available fluxes designed for austenitic stainless

steels are satisfactory. The following may also be

satisfactory.

1. Neutralized acid plus 10% acetic acid.

2. Hydrochloric acid...............90 parts by weight

Ferric chloride....................50 parts by weight

Nitric acid...........................3 parts by weight

All of the above fluxes (except rosin-base) are

strongly corrosive and must be carefully removed

from the work after soldering. When washing after

soldering is not possible, the following procedures

may be substituted for those above.

For all nickel-base alloys, use one of the fluxes

described above and precoat (“pre-tin”) the parts.

Wash them thoroughly. Use a non-corrosive rosin-

base flux for final joining.

For Nickel 200 or MONEL alloy 400, use an

organic acid flux (several proprietary fluxes are

commercially available) that is corrosive at ambient

temperatures but becomes non-corrosive when heat-

ed to soldering temperatures. All parts coated with

flux must be heated to soldering temperature.

Proper safety procedures must be followed during

the preparation and use of fluxes.

Figure 31. Mechanical joints and edge reinforcements used for joints to be soldered.

Joint Design

Joints that depend on solder alone for strength are

relatively weak. They lose strength as the tempera-

ture increases, and some solders become brittle at

low temperatures. Thus, solder alone cannot make a

strong joint; it is used only to seal the joint. Joining

techniques such as lock-seaming, riveting, spot weld-

ing, bolting should be incorporated to carry the struc-

tural load of the joint. Examples of reinforced joints

are shown in Figure 31.

HEATING METHODS

The heating methods typically used for soldering are

normally acceptable for use with nickel alloys.

Heating procedures are also similar except that the

lower thermal conductivity of some alloys may

require slightly higher temperature, longer times,

and/or more effective distribution of heat.

Overheating must be avoided, as it results in

excessive oxide formation, carbonization of the flux,

and poor joint quality.

PROCEDURES

Material to be soldered must be clean and free of for-

eign material. Surface preparation is discussed in

detail in the front of this bulletin.

Joints with long laps, such as lock-seam joints and

tubular joints, should be precoated (pre-tinned)

prior to assembly with the same material to be used

for soldering. Parts may be dipped in a molten solder

bath or the surfaces may be heated and coated with

flux and the solder flowed on. Excess solder is

removed by shaking, wiping, or brushing while it is

molten. Parts may also be protected by tin plating or

hot tin dipping.

Precipitation-hardenable materials must be sol-

dered after aging. Temperatures required for age

hardening will melt most solders. Soldering temper-

atures will not significantly affect the properties of

the aged alloys.

POST-SOLDERING TREATMENT

Most flux residues are hygroscopic. When they

absorb moisture, they may become corrosive to nick-

el alloys. Even petroleum-base fluxes become corro-

sive as they oxidize with time. Residues, therefore,

must be removed.

Washing in water or aqueous alkaline solutions

(e.g., water containing ammonia or bicarbonate of

soda) will remove most residues. If the flux binder

contains oil or grease, the material must be

degreased and then washed.

INSPECTION

Visual inspection is easily accomplished and usually

gives one a good evaluation of the quality of a sol-

dered joint. Fillets should be smooth and uninter-

rupted and should fair into the base material. Lumps

are indicative of insufficient heat. Holes or disconti-

nuities can be caused by dirty material or overheat-

ing and should be viewed with suspicion as possible

leaks. Joints which must be leaktight should be

pressure-tested.

(a)

(b)

NO.1 – SINGLE EDGE

No.16 Gauge and Lighter

NO.2 – DOUBLE EDGE

No.20 Gauge and Lighter

(a)

(b)

(c)

(d)

NO.3 – WIRED EDGE

No.20 Gauge and Lighter

(c)

NO.4 – FLAT BAND

REINFORCEMENT

No.10 Gauge and Lighter

(b)

(a)

NO.5 – CURB ANGLE

REINFORCEMENT

No.10 Gauge and Lighter

(b)

(a)

NO.6 – PLAIN LAP

No.20 Gauge and Lighter

NO.7 – STRAPPED BUTT JOINT

Soldered only. No.22 Gauge and

Lighter. Riveted and

Soldered. Any Gauge

NO.8 – RIVETED LAP

Any Gauge

NO.9 – O-GEED

Riveted Lap. Any Gauge

NO.10 – PLAIN LOCK

No.18 Gauge and Lighter

NO.11 – FLUSH LOCKED SEAM

No.18 Gauge and Lighter

NO.12 – FLANGED RIVETED

Any Gauge

NO.13 – KEYED LOCK

No.16 Gauge and Lighter

NO.14 – SIDED LOCKED SEAM

No.18 Gauge and Lighter

(a) (b)

(a)

(b)

(c)

(d)

NO.15 – STANDING END LOCK

No.16 Gauge and Lighter

(a) (b)

(c)

NO.16 – FOLDED END LOCK

No.18 Gauge and Lighter

NO.17 – INSIDE LOCK

Wood Tank Lining

No.18 Gauge and Lighter

(a)

(b) (c)

NO.18 – LOCK SEAM

No.18 Gauge and Lighter

Wood

Lock Seamed Joint

Sheet Lining

Round-Head Screw

(a)

(b)

Thermal Cutting

Introduction

Cutting Nickel Alloys

Many thermal processes can be used to successfully

cut nickel-base alloy products. Determination of the

optimum process is dependent upon the alloy, form,

and thickness of the product being cut, the required

tolerances and quality of cut, the cutting speed

required, and whether the cutting operation will be

automatic or manual.

Plasma-Arc Cutting

Cutting by the plasma-arc process is fast, versatile,

and of the highest quality. High power and gas veloc-

ity are required for cutting so that the molten metal

is blown out rather than allowed to solidify. When

the proper procedures and modern equipment are

used, little or no grinding of the cut surface is

required prior to welding.

The energy required for cutting is generated by

a high-velocity, constricted electric arc that pass-

es between a tungsten electrode and the metal to

be cut. Temperatures reach 10,000° to 40,000°F

through the decomposition of superheated gas mole-

cules into higher-energy ions and electrons or ion

pairs.

In theory, several plasma-forming gases may be

used. However, in general, nitrogen-hydrogen mix-

tures produce better results than argon-hydrogen

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((iinn))((ccffhh))TTyyppee((kkww))((iippmm))

Nickel 200 1-1/2 220 85% N2, 15% H295 25

3 260 85% N2, 15% H2138 6

6 150 65% A, 35% H2104 5

MONEL alloy 400 2 270 85% N2, 15% H2155 35

2 260 85% N2, 15% H2134 5

INCONEL alloy 600 1-3/4 220 85% N2, 15% H295 25

3 260 85% N2, 15% H2135 5

6 150 65% A, 35% H2103 5

INCONEL X-750 2-1/2 270 85% N2, 15% H2148 20

INCOLOY alloy 800 1-1/2 220 85% N2, 15% H292 20

3 260 85% N2, 15% H2163 5

6 130 65% A, 35% H298 5

mixtures. Cuts are cleaner and less sensitive to vari-

ations in settings. Cutting of very thick sections (over

5 in.), however, can best be done with the argon-hydro-

gen mixtures. While air and oxygen have been used,

they are normally avoided because of short electrode

life.

Most plasma-cutting systems use a dual flow of

gases around the electrode and through the orifice.

Nitrogen forms an inner stream to cool and protect the

electrode and form an effective, efficient plasma col-

umn. An outer sheath of air or oxygen increases cut-

ting efficiency.

Some conditions for plasma-arc cutting are shown

in Table 24. Typical cuts are seen in Figure 32. Cuts

up to 6 in. thick have been made in nickel alloys.

Because of the restricted plasma column and the

speed of the cutting process, heat-affected zones are

usually quite narrow (0.010 to 0.015 inch wide). The

cut surfaces of the thinner sections (3 inches and

less) are very smooth and exhibit little or no dross.

They are essentially square. For many applications

little or no grinding is required.

Powder Cutting

Powder cutting, a variation of the gas cutting

process, is based on the use of an oxygen jet into

which is fed a fine metal powder. The powder initi-

ates an exothermic reaction that supplies the neces-

sary heat for cutting. Nickel alloys can be readily cut

with a mixture of 70% iron and 30% aluminum.

Table 25 shows data obtained from powder cutting.

Powder cutting results in the formation and accu-

mulation of considerable amounts of oxide, dross, and

burned material on the cut metal with the greatest

buildup occurring on the top surface (Figure 33). This

slag is more adherent on nickel-copper alloys than on

nickel or nickel-chromium alloys. All adherent slag,

powder, or dross must be removed prior to any fur-

ther operation.

The heat-affected area from powder cutting is

shallow. Corrosion resistance of the metal is not sig-

nificantly affected if all discoloration is removed.

However, tolerances of powder cuts are large such

that powder cutting is limited more to severing of

large sections as opposed to cutting of small parts

requiring close tolerances.

Air Carbon-Arc Cutting

and Gouging

The air carbon-arc process utilizes a graphite elec-

trode that has been copper-coated to improve cur-

rent-carrying characteristics and lengthen service

life. Molten metal is blown away by a high-velocity

stream of air flowing from the electrode holder. A

standard constant-current SMAW power source is

used.

The process is more effective for gouging opera-

tions rather than cutting and is widely used for back-

gouging operations on welds and for the removal of

fillet welds. By controlling the depth of the groove,

limited thicknesses of material can be cut. While

grooves up to 1 inch in depth can be made in a single

pass, gouging in multiple increments of 1/4 in. depth

yield optimum control. The width of the groove is

determined primarily by the size of electrode. Torch

Figure 32. Cuts produced by plasma-arc process. (Top to bottom: Nickel 200, 1-1/2 in.; MONEL alloy 400, 2 in.;

INCOLOY alloy 800, 1-1/2 in.; INCONEL alloy 600, 1-3/4 in).

angle and speed affect the depth of the groove and

the heat-affected zone.

Operating conditions must be carefully controlled

to ensure that all molten metal is blown away from

the workpiece. Air pressure and flow must be ade-

quate. Arc voltage must be sufficiently high to devel-

op a relatively long arc so that the air stream sweeps

below the tip of the electrode. Under proper condi-

tions, the surface of the groove will be smooth and

the kerf will be small. Only light grinding is required

to prepare the groove for welding.

Gas Tungsten-Arc Cutting

The gas tungsten-arc (GTA) process may be efficient-

ly used to cut nickel alloys up to 1/8 inch in thickness.

Under some conditions materials up to 2 inches thick

may be cut. Cutting is accomplished by a constricted

arc between a 1/8 or 5/32 in. diameter thoriated tung-

sten electrode and the workpiece. The cutting action

is very fast.

For automatic cutting, the gas stream is 65%

argon and 35% hydrogen. For manual cutting, a gas

stream of 80% argon and 20% hydrogen is preferred.

The stream should be of high velocity, with flow at

about 70 cfh.

The GTA process requires a power supply capable

of delivering 400 amperes at an arc voltage of 70-85

volts. Direct current - straight polarity (electrode

negative) yields the best cutting results though the

electrode life may be quite short.

Cuts in thinner material are smooth and have a

good appearance. Cuts in thicker material may have

more oxide and dross and may not be square. Bevel

cuts can be made successfully. Typical cutting condi-

tions are shown in Table 26.

An adherent metal dross normally forms on the

bottom edge of the sections being cut. This layer can

be minimized (or even eliminated) by clamping a sac-

rificial (“waster”) plate of 3/16 or 1/4 inch mild steel

to the bottom of the material to be cut.

TTaabbllee 2255 -- PPoowwddeerr CCuuttttiinngg CCoonnddiittiioonnss

PPoowwddeerraaOOxxyyggeennNNoozzzzllee

TThhiicckknneessssSSppeeeeddCCoonnssuummppttiioonnPPrreessssuurreeDDiiaammeetteerr

MMaatteerriiaall((iinn))((iinn//mmiinn))((oozz//mmiinn))((ppssii))((iinn))CCoommmmeennttss

Nickel 200 1/4 11.0 4.5 40 0.060 Good cut.

1-5/16 4.5 9.0 65 0.100 Very rough cut

1-5/16 4.0 9.0 65 0.100 Moderately rough cut, 500°F preheat.

5 – – 75 0.200 Would not cut.

MONEL alloy 400 1/4 11.0 4.5 40 0.060 Good cut.

1/2 5.5 5.0-6.0 30 0.060 Good cut.

1 4.6 6.0 65 0.100 Rough cut.

1 4.4 6.0 65 0.100 Moderately rough cut, 500°F preheat.

5 3.0 12.0 75 0.200 Fairly smooth cut, 700°F preheat.

INCONEL alloy 600 1/4 26.0 4.0-5.0 40 0.060 Good cut.

5/8 7.0 9.0 65 0.080 Fairly smooth cut.

(a) 70% iron, 30% aluminum.

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CCoonnddiittiioonnss ((6655%% aarrggoonn,, 3355%% hhyyddrrooggeenn ggaass aatt

7700 ccffhh))

CCuuttttiinngg

MMaatteerriiaallTThhiicckknneessssCCuurrrreennttAArrccSSppeeeedd

((iinn))CCuutt((aammpp))((vvoollttss))((iippmm))

Nickel 200 3/8 Straight 430 70 60

MONEL alloy 400 3/8 Straight 430 70 60

MONEL alloy K-500 3/4 Straight 430 75 30

INCONEL alloy 600 3/8 Straight 430 70 60

3/4 Straight 420 80 25

1-1/4 Straight 500 85 20

1-1/4 Bevel 450 90 15

1-3/4 Straight 580 95 15

INCONEL alloy 3/4 Straight 420 75 30

X-750 3/4 Bevel 420 85 20

1-1/8 Straight 400 80 25

1-1//8 Bevel 400 85 15

Figure 33. Iron oxide and burned material adhering to nickel

alloy cut by powder-cutting process.

BRIGHTRAY®

CORRONEL®

DEPOLARIZED®

DURANICKEL®

FERRY®

INCOBAR®

INCOCLAD®

INCO-CORED®

INCOFLUX®

INCOLOY®

INCONEL®

INCOTEST®

INCOTHERM®

INCO-WELD®

KOTHERM®

MONEL®

NILO®

NILOMAG®

NIMONIC®

NIOTHERM®

NI-ROD®

NI-SPAN-C®

RESISTOHM®

UDIMAR®

The Special Metals Corporation

trademarks include:

UDIMET®

601GC®

625LCF®

686CPT®

718SPF™

725™

725NDUR ®

800HT®

864™

925™

956HT™

Publication Number SMC-055

The data contained in this publication is for informational purposes only and may be revised at any time

without prior notice. The data is believed to be accurate and reliable, but Special Metals makes no repre-

sentation or warranty of any kind (express or implied) and assumes no liability with respect to the accura-

cy or completeness of the information contained herein. Although the data is believed to be representative

of the product, the actual characteristics or performance of the product may vary from what is shown in this

publication. Nothing contained in this publication should be construed as guaranteeing the product for a

particular use or application.

France

Special Metals Services SA

17 Rue des Frères Lumière

69680 Chassieu (Lyon)

Phone +33 (0) 4 72 47 46 46

Fax +33 (0) 4 72 47 46 59

Germany

Special Metals Deutschland Ltd.

Postfach 20 04 09

40102 Düsseldorf

Phone +49 (0) 211 38 63 40

Fax +49 (0) 211 37 98 64

Hong Kong

Special Metals Pacific Pte. Ltd.

Room 1110, 11th Floor

Tsuen Wan Industrial Centre

220-248 Texaco Road, Tsuen Wan

Phone +852 2439 9336

Fax +852 2530 4511

India

Special Metals Services Ltd.

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Block

Vasantha Vallabha Nagar

Subramanyapura Post

Bangalore 560 061

Phone +91 (0) 80 666 9159

Fax +91 (0) 80 666 8918

Italy

Special Metals Services SpA

Via Assunta 59

20054 Nova Milanese (MI)

Phone +390 362 4941

Fax +390 362 494224

The Netherlands

Special Metals Service BV

Postbus 8681

3009 AR Rotterdam

Phone +31 (0) 10 451 44 55

Fax +31 (0) 10 450 05 39

Singapore

Special Metals Pacific Pte. Ltd.

50 Robinson Road

06-00 MNB Building, Singapore

068882

Phone +65 6222 3988

Fax +65 6221 4298

Affiliated Companies

Special Metals Welding

Products

1401 Burris Road

Newton, NC 28658, U.S.A.

Phone +1 (828) 465-0352

+1 (800) 624-3411

Fax +1 (828) 464-8993

Regal Road

Stratford-upon-Avon

Warwickshire CV37 0AZ, U.K.

Phone +44 (0) 1789 268017

Fax +44 (0) 1789 269681

Controlled Products Group

590 Seaman Street, Stoney Creek

Ontario L8E 4H1, Canada

Phone +1 (905) 643-6555

Fax +1 (905) 643-6614

A-1 Wire Tech, Inc.

A Special Metals Company

840 39th Avenue

Rockford, IL 61109, U.S.A.

Phone +1 (815) 226-0477

+1 (800) 426-6380

Fax +1 (815) 226-0537

Rescal SA

A Special Metals Company

200 Rue de la Couronne des Prés

78681 Epône Cédex, France

Phone +33 (0) 1 30 90 04 00

Fax +33 (0) 1 30 90 02 11

DAIDO-SPECIAL METALS

Ltd.

A Joint Venture Company

Daido Building

7-13, Nishi-shinbashi 1-chome

Minato-ku, Tokyo 105, Japan

Phone +81 (0) 3 3504 0921

Fax +81 (0) 3 3504 0939

U.S.A.

Special Metals Corporation

Billet, rod & bar, flat

& tubular products

3200 Riverside Drive

Huntington, WV 25705-1771

Phone +1 (304) 526-5100

+1 (800) 334-4626

Fax +1 (304) 526-5643

Billet & bar products

4317 Middle Settlement Road

New Hartford, NY 13413-5392

Phone +1 (315) 798-2900

+1 (800) 334-8351

Fax +1 (315)798-2016

Atomized powder products

100 Industry Lane

Princeton, KY 42445

Phone +1 (270) 365-9551

Fax +1 (270) 365-5910

Shape Memory Alloys

4317 Middle Settlement Road

New Hartford, NY 13413-5392

Phone +1 (315) 798-2939

Fax +1 (315) 798-6860

United Kingdom

Special Metals Wiggin Ltd.

Holmer Road

Hereford HR4 9SL

Phone +44 (0) 1432 382200

Fax +44 (0) 1432 264030

Special Metals Wire Products

Holmer Road

Hereford HR4 9SL

Phone +44 (0) 1432 382556

Fax +44 (0) 1432 352984

China

Special Metals Pacific Pte. Ltd.

Room 1802, Plaza 66

1266 West Nanjing Road

Shanghai 200040

Phone +86 21 6288 1878

Fax +86 10 6288 1811

Special Metals Pacific Pte. Ltd.

Room 118, Ke Lun Mansion

12A Guanghua Road

Choa Yang District

Beijing 100020

Phone +86 10 6581 8396

Fax +86 10 6581 8381

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