SuperGlaze Aluminum MIG Welding Guide (pdf) Metallurgy And

User Manual: Aluminum-Metallurgy-And-Welding Igor's of metalworking and electrical manuals

Open the PDF directly: View PDF .
Page Count: 32

Gas Metal Arc Welding for Aluminum

Aluminum GMAW Welding Guide

2

www.lincolnelectric.com

Aluminum

For superior welding performance, turn to Super Glaze®aluminum

MIG wire from Lincoln Electric®. Super Glaze®prevents the problems

usually associated with aluminum wire feeding such as birdnesting,

tangling and burnback to provide a stable arc, great feedability and

exceptional control –– every time you weld! The keys are Super

Glaze’s smooth surface finish and consistent chemical composition.

What this means for you is quality wire that produces a quality weld.

Let Us Put Our Experience to Work for You

As a major supplier of welding wire, Lincoln Electric®is the leader in

MIG wire manufacturing technology. We carry that same technology

and expertise to our aluminum MIG wire manufacturing. Our fully

integrated aluminum MIG wire facility uses state-of-the-art equipment

to produce a complete range of aluminum alloys including 1100, 4043

4047, 5183, 5356, 5554 and 5556.

What Makes Our Super Glaze®Stand Out From the Rest?

Three unique features:

1. A proprietary process which gives Super Glaze®a superior surface

finish for optimum surface integrity.

2. A manufacturing process that precisely controls the alloy chemical

composition to produce consistent physical

characteristics.

3. State-of-the-art testing equipment to evaluate the

surface condition and feedability of the wire to ensure

problem-free welding.

What all this means to you is outstanding welding characteristics, spool

to spool, time after time. Lincoln’s aluminum MIG wire coupled with our

advanced MIG welding equipment makes aluminum as easy to weld as

any other material... and makes Lincoln®the one source for all your

aluminum welding needs.

Lincoln Electric

®

is the world’s leading

manufacturer of welding equipment and

consumables. Our focus is on helping

companies make their welding

operations more effective, more

efficient, more profitable.

We are dedicated to two equally

important goals: exceptional quality and

exceptional service. Our field support

team –– with hundreds of field sales

engineers and thousands of

knowledgeable and responsive Lincoln

®

distributors in countries all over the

world –– is the largest in the industry.

Innovative thinking.

A quality, service-first attitude.

Fresh approaches to design,

manufacturing, and packaging.

Worldwide strength.

That’s Lincoln Electric

®

.

LLiinnccoollnn’’ss SSuuppeerr GGllaazzee®®TTeecchhnnoollooggyy

AAbboouutt TThhee LLiinnccoollnn

EElleeccttrriicc CCoommppaannyy®®

Important Information on our Website

Consumable AWS Certificates:

www.lincolnelectric.com/products/certificates/

Material Safety Data Sheets (MSDS):

www.lincolnelectric.com/products/msds/

ANSI Z49.1 Safety in Welding and Cutting and Arc Welding

Safety Checklist:

www.lincolnelectric.com/community/safely/

Request E205 Safety Booklet:

www.lincolnelectric.com/pdfs/products/literature/e205.pdf

3

Aluminum

www.lincolnelectric.com

Here’s How Our Process Works:

Controlling Alloys

The process of making aluminum MIG wires is a complex one,

but one in which Lincoln®has a clear and distinct advantage.

First, we utilize automated titling furnaces to efficiently produce

the proper aluminum alloys. With this equipment, we are able to

hold tight tolerances in the composition. The alloy is carefully

refined prior to casting to minimize hydrogen, alkaline metals,

and inclusions.

Continuous Casting

Second, we use a continuous casting process specially

configured to high alloy materials. This process keeps the

surface free from imperfections and impurities.

Drawing the Wire

In the last manufacturing step of the process, we use advanced

wire drawing technology to preserve both surface integrity and

internal soundness.

Testing the Wire

To ensure superior quality of welding wire, continuous finished

product inspection is done. Surface quality is evaluated along

with feedability and welding performance. This guarantees every

spool of wire is problem-free.

Welding Performance

Most aluminum MIG welding problems are caused by poor

feeding. Since aluminum is relatively soft, it is important that the

wire surface be as smooth as

possible for best feedability.

Super Glaze®products provide

easier feeding than competitive

products because they have

fewer surface imperfections as

shown at the right.

Super Glaze®wire also feeds

with less force than typical

competitive products as the

feedability test graph shows.

What this means is better

control of the weld puddle for

the operator. t also means longer

gun liner and contact tip life as

burnbacks do not occur.

With our MIG welding process knowledge, we understand that

welding performance is one of the most important criteria used

when selecting a wire. Aluminum MIG wire tends to produce a

welding arc that is less stable than other materials because

aluminum conducts electricity better. Small changes in wire

diameter, wire feed speed, and current produce dramatic

changes in weld bead profile, arc length and can even cause

equipment downtime due to wire burnback and fusing to tip.

Our continuous evaluation of finished product ensures

consistency in manufacturing. You can count on Lincoln®

aluminum MIG wire for superior arc stability, weld appearance,

integrity and productivity.

The SuperGlaze Advantage

5356 Wire Surfaces Magnified 60x

Typical Competitive

Product

SuperGlaze

“Best in Class”

Excellent

Time

Poor

Wire Jams and Stops Feeding

Feedability

Lincoln

SuperGlaze™

Product

Typical

Competitive

Product

Typical

Competitive

Product

4

www.lincolnelectric.com

Aluminum

Contents Page

Effects of Alloying Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Welding Aluminum vs. Welding Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Metallurgy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Wrought Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Cast Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Alloying Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7

Temper Designations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8

Effects of Welding on Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Nonheat-treatable Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Heat-treatable Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Filler Metal Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-12

Aluminum Filler Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11

Aluminum Filler Metal Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Welding Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-14

Storage and Handling of Aluminum Prior to Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Forming the Weld Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Pre-weld Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-14

GMAW of Aluminum Alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-18

Properties of Aluminum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Modes of Metal Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

GMAW Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-16

GMAW-P Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Wire Drives and Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-17

Push and Push-Pull Type Feeders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-17

Push-Pull GMAW Torches and Spool Guns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Aluminum Feeding Enhancement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Shielding Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Welding Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Welding Defects — Causes and Cures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-20

Solving Problems in Qualifying Weld Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Meeting Tensile Test Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-22

Meeting Bend Test Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-22

General Welding Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-26

Typical Melting Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Current vs. Wire Feed Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Welding Joint Design for Groove Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-25

Welding Guidelines for Fillet and Lap Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Safety Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27-30

5

Aluminum

www.lincolnelectric.com

Effects of Alloying Elements

Introduction

The use of aluminum as a structural material is fairly recent. In

fact, when the Washington Monument was completed in

December, 1884, it was capped with a 100-ounce pyramid of

pure aluminum, because aluminum was considered to be a

precious metal at that time. The problem that impeded the use

of aluminum is that it is a reactive metal. It is never found in its

elemental state in nature, but is always tightly bound with

oxygen as aluminum oxide, Al2O3. Although aluminum oxide,

found as bauxite ore, is plentiful, no direct reduction method,

such as they used to make steel, has ever been found to produce

aluminum from bauxite.

It was only after the American Charles M. Hall and the

Frenchman Paul Heroult almost simultaneously, but indepen-

dently, discovered electrolytic processes for obtaining pure

aluminum from aluminum oxide (in 1886) that aluminum became

available in commercial quantities. These processes, with some

modifications, are still used today. In large part, it is the extremely

large amount of electrical power required to produce aluminum

that accounts for its higher cost relative to steel.

Since that time, aluminum has found wide use in numerous

applications:

• It conducts electricity and heat almost as well as copper.

• It is widely used in electrical bus bars and other conductors,

heat exchangers of all kinds, and cookware.

• It does not become brittle with decreasing temperature, but

does become stronger, so it has found wide application in

cryogenic equipment at temperatures as low as –452°F

(-269°C).

• It is very corrosion resistant in most environments, so it has

found wide applications in marine and chemical environments.

The characteristics of aluminum alloys which make them

attractive as structural materials are their light weight (one third

the weight of steel for equal volumes) and their relatively high

strength (equal in many cases to that of construction steel

grades). This combination has resulted in increased use of

aluminum alloys in applications such as passenger automobiles,

trucks, over-the-road trailers, and railroad cars. Additionally, the

structure of most aircraft is fabricated mainly from aluminum

alloys, although in these applications, pieces are most often

joined by riveting.

Welding Aluminum vs. Welding Steel

Most welders start out by learning how to weld steel. Some later

move over to welding aluminum. Most welding equipment is

designed to weld steel, with welding of aluminum alloys often

being an afterthought, although this is changing. Very often we

approach welding of aluminum as if it was just shiny steel.

However, there are differences between steel and aluminum that

usually make this approach doomed to failure.

The balance of this guide will discuss these differences and how

to overcome them. They can all be summed up in three

statements:

I. If you take enough care almost all steels are weldable.

There are some aluminum alloys that just are not arc weldable.

Fabricators fall into this trap regularly. We’ll discuss the

weldability of the various alloy families in detail. At this point, let’s

just say that many aluminum alloys, and especially the stronger

ones, are not weldable.

2. All steels are heat-treatable. Some aluminum alloys are

heat-treatable, but some are not.

Even for the heat-treatable aluminum alloys, the heat treatments

are totally different from those used for steel. In fact, if you heat

up some alloys and quench them, they will become softer, not

harder. Be aware of the differences and act accordingly.

3. When welding steels, you can almost always make a weld

that is as strong as the parent material. In aluminum alloys,

the weld will rarely be as strong as the parent material.

This is usually true for welds in both heat treatable and nonheat-

treatable alloys. The strength difference between the weld or

heat affected zone (HAZ) and the parent material is often

significant, often 30% or more.

Metallurgy

To understand aluminum, we must first understand some basics

about aluminum metallurgy. Aluminum can be alloyed with a

number of different elements, both primary and secondary, to

provide improved strength, corrosion resistance, and general

weldability.

The primary elements that alloy with aluminum are copper, silicon,

manganese, magnesium and zinc. It is important to note that

aluminum alloys fall into two classes: heat-treatable or

nonheat-treatable.

Heat-treatable alloys are those that are heat-treated to increase

their mechanical properties. To heat treat an alloy means heating

it at a high temperature, putting the alloying elements into solid

solution and then cooling it at a rate which will produce a super

saturated solution. The next step in the process is to maintain it

at a lower temperature long enough to allow a controlled

amount of precipitation of the alloying elements.

With the nonheat-treatable alloys it is possible to increase

strength only through cold working or strain hardening. To do

this, a mechanical deformation must occur in the metal

structure, resulting in increased resistance to strain, producing

higher strength and lower ductility.

6

www.lincolnelectric.com

Aluminum

Alloying Elements

Pure Aluminum (1XXX series) Contains no alloying elements,

and is not heat-treatable. It is used primarily in chemical tanks

and pipe because of its superior corrosion resistance. This series

is also used in electrical bus conductors because of its excellent

electrical conductivity. It is welded easily with 1100 and 4043 filler

wires.

Copper (2XXX series) Provides high strength to aluminum. This

series is heat-treatable and mainly used in aircraft parts, rivets

and screw products. Most 2XXX series alloys are considered

poor for arc welding because of their sensitivity to hot cracking.

Most of these alloys should not be welded, however, alloys

2014, 2219 and 2519 are easily welded with 4043 or 2319 filler

wire. These three alloys are widely used in welded fabrication.

Manganese (3XXX series) Yields a nonheat-treatable series

used for general-purpose fabrication and build-up. Moderate in

strength, the 3XXX series is used for forming applications

including utility and van trailer sheet. It is improved through strain

hardening to provide good ductility and improved corrosion

properties. Typically welded with 4043 or 5356 filler wire, the

3XXX series is excellent for welding and not prone to hot cracking.

Its moderate strengths prevent this series from being used in

structural applications.

Silicon (4XXX series) Silicon reduces the melting point of the

aluminum and improves fluidity. Its principle use is as filler metal.

The 4XXX series has good weldability and is considered a

nonheat-treatable alloy. Alloy 4047 is often used in the

automotive industry as it is very fluid and good for brazing and

welding.

Magnesium (5XXX series) When added to aluminum,

magnesium has excellent weldability, good structural strength

and is not prone to hot cracking. In fact, the 5XXX series has the

highest strength of the nonheat-treatable aluminum alloys. It is

used for chemical storage tanks and pressure vessels as well as

structural applications, railway cars, dump trucks and bridges

because of its corrosion resistance.

Aluminum Alloys

Much in the same manner that the American Iron and Steel

Institute (AISI) registers steel chemistries and grades, the

Aluminum Association (AA) registers alloy designations,

chemistries, and mechanical properties for aluminum alloys.

However, the alloy designation system is totally different than

that used for steels. Additionally, different designation systems

are used for wwrroouugghhttand ccaassttalloys.

Wrought Alloys

Wrought alloy designations use a four digit number, plus a

temper designation, discussed later. Aluminum alloys are

broken up into eight "families" depending on the main alloying

elements. The aluminum alloy families are shown in Table 1,

along with their heat treatability.

For example, if you have a piece of 6061, it’s clear that it is a

wrought alloy (4 digits), it’s heat treatable, and it contains

magnesium and silicon. The second digit of the four shows

whether the alloy is the first such alloy registered, in which case

the second digit will be "0", as in 5054. Digits other than "0"

indicate that the alloy is a modification of a registered alloy. 5154

would be the first modification of 5054. Alloy 5754 is the

seventh modification. The last two digits are assigned arbitrarily

by the Aluminum Association when the alloy is registered. Note

there is no indication of alloy or weld strength given by the

material designation.

Alloy Heat

Family Main Alloying Elements Treatable

1XXX Pure Aluminum No

2XXX Copper (sometimes with magnesium) Yes

3XXX Manganese (sometimes with magnesium) No

4XXX Silicon No

5XXX Magnesium No

6XXX Magnesium plus silicon Yes

7XXX Zinc (sometimes with magnesium and copper) Yes

8XXX All others Normally

Yes

NOTE: The designation 2XXX, etc. is an industry standard abbreviation

used to mean “all the alloys in the 2000 series”.

Table 1: Wrought Alloy Destinations

Alloy Heat

Family Main Alloying Elements Treatable

1XX.X Pure Aluminum No

2XX.X Copper Yes

3XX.X Silicon plus magnesium Yes

4XX.X Silicon Yes

5XX.X Magnesium No

6XX.X Not Used NA

7XX.X Zinc Yes

8XX.X Tin No

9XX.X Other

Table 2 — Cast Alloy Destinations

Cast Alloys

The designation system for cast alloys are classified into families

as shown in Table 2. The specific families are somewhat

different from the designations for wrought alloys and the

designations have only three digits followed by a decimal point

and one more digit. For these alloys, the first digit shows the

alloy family. The next two digits are arbitrarily assigned. Alloy

modifications are shown by a letter prefix, so 356 is the original

version of an alloy and A356 is the first modification, B356 is the

second modification, etc. The number following the decimal

point designates whether the alloy is produced as a casting of

final form or is produced as an ingot for re-melting.

7

Aluminum

www.lincolnelectric.com

Silicon and Magnesium (6XXX series) This medium strength,

heat-treatable series, is primarily used in automotive, pipe,

railings, and structural extrusion applications. The 6XXX series is

prone to hot cracking, but this problem can be overcome by the

correct choice of joint and filler metal. Can be welded with either

5XXX or 4XXX series without cracking — adequate dilution of the

base alloys with selected filler wire is essential. A 4043 filler wire

is the most common for use with this series. 6XXX alloys should

never be welded autogenously, they will crack.

Zinc (7XXX series) Zinc added to aluminum with magnesium

and copper produces the highest strength heat-treatable

aluminum alloy. It is primarily used in the aircraft industry. The

weldability of the 7XXX series is compromised in higher copper

grades, as many of these grades are crack sensitive (due to

wide melting ranges and low solidus melting temperatures).

Grades 7005 and 7039 are weldable with 5XXX filler wires. They

are widely used for bicycle frames and other extruded

applications.

Other (8XXX series) Other elements that are alloyed with alu-

minum (i.e. lithium) all fall under this series. Most of these alloys

are not commonly welded, though they offer very good rigidity

and are principally used in the aerospace industry. Filler wire

selection for these heat-treatable alloys include the 4XXX series.

In addition to the primary aluminum alloying elements, there are

a number of secondary elements, which include chromium, iron,

zirconium, vanadium, bismuth, nickel and titanium. These ele-

ments combine with aluminum to provide improved corrosion

resistance, increased strength and better heat treatability.

Figure 1: Relationship of Yield Strength, Amount of Cold

Work and Alloy Content

Temper Designations

The information above allows an aluminum alloy to be recognized

by its chemistry, but not by the heat treatment or mechanical

properties. To show these properties, temper designations are

assigned. The complete designation of an alloy might be 6061-T6

or 5083–H114. Most of these designations are different for heat-

treatable and nonheat-treatable alloys; however, two common

designations apply to all alloys:

• "O" Temper (not zero). When an alloy is given this designation,

the supplier has annealed the alloy, typically at 650-750°F

(343-300°C), and it is as soft as possible.

• "F" Temper. When an alloy is supplied in this temper it is

supplied "as fabricated". This means the supplier is guaran-

teeing that the chemistry of the material meets the chemical

requirements for the specified alloy, but there are no claims

regarding the mechanical properties of the alloy. This temper

is often specified by fabricators who subsequently forge or

form the supplied material and establish mechanical

properties by heat treatment after forming.

To discuss the remainder of the temper designations, we need

to discuss the heat-treatable and nonheat-treatable alloys.

Nonheat-Treatable Alloys — Strain-Hardened Designations

These alloys cannot be strengthened by heat treatment.

However, they can be strengthened by ccoolldd wwoorrkkiinngg,,also called

ssttrraaiinn hhaarrddeenniinngg. If an aluminum alloy is deformed at elevated

temperatures, [600°F (315°C) or higher], little or no strengthening

takes place. However, if the alloy is deformed at lower

temperatures, it will gain strength. In general:

• The more the alloy is deformed, the stronger it gets. Finally, at

some point, the alloy will have no ductility and will fracture.

• The higher the alloy content, the more it will gain strength by

being deformed.

Both of these phenomena are shown in Figure 1.

The temper designation for strain hardened alloys is usually

made up of two digits as shown in Table 3.

The first digit shows whether the alloy is only strained or whether

it has been partially annealed and/or stabilized. The second digit

shows how much strain hardening has been put into the alloy.

Higher numerical values mean higher strain levels, which means

higher yield and tensile strengths.

First Digit Indicates Basic Operations

H1 — Strain Hardened Only

H2 — Strain Hardened and Partially Annealed

H3 — Strain Hardened and Stabilized

Second Digit Indicates Degree of Strain Hardening

HX2 — Quarter Hard

HX4 — Half Hard

HX6 — Three-Quarters Hard

HX8 — Full Hard

HX9 — Extra Hard

Table 3: “H” Temper Designations

Heat Treatable Alloys

Strain hardened “H” tempers are not used for heat-treatable

alloys. Instead a series of “T” tempers indicating the heat

treatment state are used. A total of (10) tempers exist; “T1”

through “T10”. The commonly seen designations are “T4”

and “T6”. All 10 designations are listed in Table 4 on the

following page.

T1 Cooled from an elevated temperature shaping process

and naturally aged to a substantially stable condition.

Applies to products that are not cold worked after cooling

from an elevated temperature shaping process, or in which

the effect of cold work in flattening or straightening may not

be recognized in mechanical property limits.

T2 Cooled from an elevated temperature shaping process,

cold worked and naturally aged to a substantially stable

condition. Applies to products that are cold worked to

improve strength after cooling from an elevated temperature

shaping process, or in which the effect of cold work in flatten-

ing or straightening is recognized in mechanical property limits.

T3 Solution heat-treated(1),cold worked and naturally aged

to a substantially stable condition. Applies to products that

are not cold worked to improve strength after solution heat

treatment, or in which the effect of cold work in flattening or

straightening is recognized in mechanical property limit.

T4 Solution heat-treated(1) and naturally aged to a

substantially stable condition. Applies to products that are

cold worked after solution heat-treatment, or in which the

effect of cold work in flattening or straightening may not be

recognized in mechanical property limits.

T5 Cooled from an elevated temperature shaping process

and then artificially aged. Applies to products that are not

cold worked after cooling from an elevated temperature

shaping process, or in which the effect of cold work in

flattening or straightening may not be recognized in mechanical

property limits.

T6 Solution heat-treated(1) and then artificially aged. Applies

to products that are not cold worked after solution heat-

treatment, or in which the effect of cold work in flattening or

straightening may not be recognized in mechanical property

limits.

8

www.lincolnelectric.com

Aluminum

Aluminum alloys are heat treatable because of a phenomenon

called precipitation hardening. They do not harden by a

martensitic transformation as steel does. In precipitation

hardening, one metal can be dissolved in another in a "solid

solution" and solubility generally increases with temperature. For

example, just as sugar will dissolve in a glass of iced tea when

heated — copper, zinc or combinations of magnesium and

silicon will dissolve in aluminum as it is heated.

When the heat-treatable alloys are heated to approximately

950°F (510°C), and held for a few minutes, all the alloying

elements are taken into a solution in the solid aluminum. This is

termed a "solution heat treatment". Normally, the alloy is

quenched in water from this point to arrive at the T4 temper.

Although the T4 temper is substantially stronger than the

annealed “O” temper, the primary purpose of quenching is not

strengthening. Instead, the quenching serves to keep the alloy

additions in solution at room temperature — if the aluminum

were cooled slowly from the solution treatment, the alloying

additions would re–precipitate and no strengthening would

occur.

Table 4 — T1 through T10 Temper Designations

T7 Solution heat-treated(1) and overaged/stabilized. Applies

to wrought products that are artificially aged after solution heat

treatment to carry them beyond a point of maximum strength to

provide control of some significant characteristic(2). Applies to

cast products that are artificially aged after solution heat

treatment, to provide dimensional and strength stability.

T8 Solution heat-treated(1), cold worked, and then artificially

aged. Applies to products that are cold worked to improve

strength, or in which the effect of cold work in flattening or

straightening is recognized in mechanical property limits.

T9 Solution heat-treated(1), artificially aged, and then cold

worked. Applies to products that are cold worked to

improve strength.

T10 Cooled from an elevated temperature shaping process,

cold worked, and then artificially aged. Applies to

products that are cold worked to improve strength, or in

which the effect of cold work in flattening or straightening is

recognized in mechanical property limits.

(1) Solution heat treatment is achieved by heating cast or wrought products

to a suitable temperature, holding at that temperature long enough to

allow constituents to enter into solid solution and cooling rapidly enough

to hold the constituents in solution. Some 6XXX series alloys attain the

same specified mechanical properties whether furnace solution heat

treated or cooled from an elevated temperature shaping process at a rate

rapid enough to hold constituents in solution. In such cases, the temper

designations T3, T4, T6, T7, T8 and T9 are used to apply to either

process and are appropriate designations.

(2) For this purpose,

characteristic

is something other than mechanical

properties. The test method and limit used to evaluate material for this

characteristic are specified at the time of the temper registration.

The tensile and yield strengths of the material will increase for

several weeks after the heat treatment and, in some alloys, can

increase significantly. However, once past this initial period, the

alloy is stable indefinitely. The user normally is unaware of this

initial strength increase because the aluminum producer doesn’t

ship the alloy until the strength has stabilized.

The T4 temper, while stable, does not give maximum strength to

the alloy. Most alloys are sold in a maximum strength T6 temper.

To get from T4 to T6 temper, the material is put in a furnace at a

temperature of 325°F to 400°F (163°C to 204°C) and allowed to

age 1 to 5 hours. The dissolved alloying elements will form

submicroscopic pre-precipitates in the material and produce

maximum strength. If this aging heat treatment is carried out at

too high a temperature or for too long, the precipitates will get

too large and a lower strength "overaged" condition will result.

Note: This final aging heat treatment is carried out at 400°F (204°C)

maximum. The welding heat, which can heat the surrounding material to

well over this temperature, can significantly degrade the strength of the

weld heat affected zone (HAZ), which is discussed in more detail on the

following page.

9

Aluminum

www.lincolnelectric.com

As before, it is easiest to discuss the effects of welding on the

mechanical properties of aluminum weldments if we discuss

nonheat-treatable alloys and heat-treatable alloys separately.

Nonheat-Treatable Alloys

As was discussed earlier, these alloys can be, and often are,

strengthened by cold working. Cold worked alloys can have

yield and tensile strengths twice those of the annealed "O"

temper alloy. These cold worked alloys can be softened back to

the "O" temper by annealing at 650-700°F (343-371°C). Since

the heat of welding produces temperatures considerably higher

than this at the weld fusion line, the result of welding is that the

heat affected zone (HAZ) of welds in nonheat-treatable alloys (ie,

1XXX, 3XXX, 4XXX, and 5XXX alloys) becomes annealed.

Therefore, the strength of the weld joint is always equal to the

strength of the "O" temper annealed base material, regardless of

what the starting temper of the parent material was. If you weld

"O" temper material, the weld will be as strong as the starting

parent material. If you weld any material that is strain hardened

(ie, cold worked), the weld will be weaker than the starting

material, perhaps significantly weaker.

The HAZ can never become softer then the "O" temper, so that

excess welding heat input will not make the HAZ softer. It can,

however, make the HAZ wider. Normally, this will not further

reduce the strength of the welded joint, although other problems

can arise due to excessive heat input.

From a practical standpoint, there is no way to regain the

strength lost during welding. If the weld is cold worked, it will

begin to work harden again. However, this is not usually a

practical industrial solution, because, in most cases, the weld

will not be as strong as the starting cold worked material.

Heat-Treatable Alloys

There is no blanket statement that can be made about the

welded strength of heat-treatable alloys. As previously stated,

the weld will generally be weaker than the parent material.

However, the welded properties will strongly depend on the

temper of the material before welding and also on heat

treatments performed after welding. Figure 2 shows a

micro-hardness trace across a weld, starting at the center of the

weld. The graph actually shows four curves representing what

happens to material in the T4 and T6 tempers in the as-welded

(AW) and postweld heat-treated (PWA) conditions. The following

can be noted:

1) The HAZ is about 1/2” (12.7 mm) wide. The actual width of

the HAZ will depend on a number of things, including the

welding process used and the thickness of the material.

HAZ widths of 1” (25.4 mm) are not uncommon in thin materials.

2) The hardness and strength of the weldment is typically lowest

in the HAZ. Because of this, strength of the welding filler alloy is

not a primary concern when making butt welds. A weld will most

often fail in the HAZ.

3) Unlike nonheat-treatable alloys, the hardness (and therefore

strength) in the HAZ is not always the same. It depends on the

material temper prior to welding and whether the weld is

post-weld aged.

a) The weakest HAZ occurs when the material is welded in the

T6 temper and used as–welded.

b) The HAZ, and therefore the weldment, will actually be slightly

stronger if the material is used in the T4 temper and used

as–welded.

c) If the weldment in either T4 or T6 material is post-weld aged,

the strength of the HAZ can increase significantly. The exact

postweld heat treatment varies with the alloy, but is usually an

aging at around 400°F (204°C) for about one hour.

The fabricator has some options that he doesn’t have when

fabricating the nonheat-treatable alloys in terms of recovering

some of the strength lost during welding. For instance, since the

6XXX alloys also bend easier and around a smaller radius in the

T4 temper than in the T6 temper, these alloys can be bought in

the T4 temper, formed easily, welded, and then aged. The

resulting mechanical properties will be significantly higher than if

the material was purchased in the T6 temper.

Finally, if the right filler alloy is chosen, the finished weldment can

be completely heat-treated and the T6 properties restored. This

requires a re-solution heat treatment, quench, and re-aging. This

is often practical for small structures, but not for large ones. For

example, aluminum bicycle frames are often fabricated in this

way.

The HAZ of welds in heat-treatable alloys is significantly different

than those in nonheat-treatable alloys. The strength of the HAZ

in heat-treatable alloys can be made considerably wider and

weaker if excessive heat input is used. Therefore, it is very

important not to use excessive preheats [200°F (93°C)

maximum is recommended], to carefully monitor interpass

temperatures [250°F (121°C) maximum is recommended], and

to avoid practices such as wide weave passes which will result

in excessive heat input.

Figure 2: Hardness vs. Distance for 6061-T4 and -T6 in the

as-welded and post-weld aged conditions.

Effects of Welding on Mechanical Properties of Aluminum Alloys

AWS A5.10-99

ASME SFA-5.10

Classification

%Mn %Si %Fe %Mg %Cr %Cu %Ti %Zn %Be %Others(1) %Al

ER1100 & 0.05 — —— — 0.05-0.20 — 0.10 0.05 99.0

Alloy 1050

ER2319 0.20-0.40 0.20 0.30 0.02 — 5.8-6.8 0.10-0.20 0.10 (2) 0.05(3) Balance

ER4043 0.05 4.5-6.0 0.8 0.05 — 0.30 0.20 0.10 (2) 0.05 Balance

ER4047 0.15 11.0-13.0 0.8 0.10 — 0.30 — 0.20 (2) 0.05 Balance

Alloy 5052 0.10 0.25 0.40 2.2-2.8 0.15-0.35 0.10 — 0.10 (2) 0.05 Balance

Alloy 5056 0.05-0.20 0.30 0.40 4.5-5.6 0.05-0.20 0.10 — 0.10 (2) 0.05 Balance

Alloy 5154 0.10 0.25 0.40 3.1-3.9 0.15-0.35 0.10 0.20 0.20 (2) 0.05 Balance

ER5183 0.50-1.0 0.40 0.40 4.3-5.2 0.05-0.25 0.10 0.15 0.25 (2) 0.05 Balance

ER5356 0.05-0.20 0.25 0.40 4.5-5.5 0.05-0.20 0.10 0.06-0.20 0.10 (2) 0.05 Balance

ER5554 0.50-1.0 0.25 0.40 2.4-3.0 0.05-0.20 0.10 0.05-0.20 0.25 (2) 0.05 Balance

ER5556 0.50-1.0 0.25 0.40 4.7-5.5 0.05-0.20 0.10 0.05-0.20 0.25 (2) 0.05 Balance

ER5654 0.01 — — 3.1-3.9 0.15-0.35 0.05 0.05-0.15 0.20 (2) 0.05 Balance

10

www.lincolnelectric.com

Aluminum

Filler Metal Selection

Aluminum Filler Alloys

Most common aluminum filler alloys fall into the 4XXX and 5XXX

families, with a few coming from the 1XXX, 2XXX, and the

casting alloys. The chemical composition of the common

aluminum filler alloys is shown in Table 5, below.

There are a number of characteristics which determine the best

filler metal choice for a given base material, or combination of

base materials. Among these are:

• Freedom from hot cracking.

• Weld metal ductility.

• Weld metal corrosion resistance.

• Weld metal shear strength in fillet and lap joints.

• Ease of welding (i.e., weldability).

• Filler wire feedability.

• Weld color match with parent metal for applications requiring

postweld anodizing.

There are a number of filler metal selection charts which have

taken these factors into account and give good overall

recommendations for filler metal selection. A composite of these

charts covering most alloy combinations are shown in Table 7

on page 12.

In general, filler alloy recommendations for the various alloy

families can be summarized as follows:

1XXX alloys — These alloys are usually used for their electrical

conductivity and/or corrosion resistance. Their sensitivity to hot

cracking is very low. They are usually welded using 1100 or

1188 fillers, but matching filler metals are also available for

specialized alloys such as 1350. If electrical conductivity of the

joint is not of primary importance, 4043 may be used.

2XXX alloys — Many alloys in this series are not arc weldable.

Those that are include 2219, 2014, 2519, 2008, and 2036. Alloy

2319 is a matching filler alloy for 2219 and 2519 and can also

be used on the other weldable alloys. Alloys 4043 and 4145,

which contain copper, can also be used. Alloy 5XXX fillers

should not be used to weld 2XXX parent materials, because

cracking will result.

3XXX alloys — These moderate strength aluminum–manganese

alloys are relatively crack resistant and can be welded easily

using either 4043 or 5356.

4XXX alloys — These alloys are usually found as welding or

brazing fillers. In the rare event they are encountered as parent

materials, 4047 is usually the best choice as a filler metal.

Table 5

(1) Total of “others” shall not exceed 0.15%.

(2) Beryllium shall not exceed 0.0003%.

(3) Vanadium content shall be 0.05 - 0.15% and Zirconium content shall be 0.10 - 0.25%.

NOTE: Single values are maximum, except aluminum.

WIRE CHEMICAL COMPOSITION FOR COMMON ALUMINUM WIRES

Aluminum

AWS Lincoln

Classification Product Name

ER1100 Super Glaze®1100

ER4043 Super Glaze 4043

ER4047 Super Glaze 4047

ER5183 Super Glaze 5183

ER5356 Super Glaze 5356

ER5554 Super Glaze 5554

ER5556 Super Glaze 5556

11

Aluminum

www.lincolnelectric.com

Super Glaze®Aluminum GMAW Wire

5XXX alloys — These higher strength aluminum–magnesium

alloys are the most common structural aluminum sheet and

plate alloys. The general rule, except for the alloy 5052, is to

choose a 5XXX filler metal with slightly higher magnesium

content than the parent material being welded. For all alloys

except 5052, 5XXX alloys should not be welded using 4XXX filler

alloys. The high Mg content of the parent material, when

combined with the high Si content of the 4XXX fillers, will result

in a high level of Mg2Si — a brittle intermetallic compound which

will cause the weld to have poor ductility and toughness. In

choosing filler alloys for 5XXX alloys, there are several specific

recommendations as follows:

5052 — This alloy has just the right amount of Mg content to

exhibit a relatively high crack sensitivity. If it is welded with

5052 filler alloy, it will often crack. To avoid the tendency to

crack, 5052 is usually welded with a filler alloy of much higher

Mg content, such as 5356. The resulting weld metal, which is

an alloy of the 5356 and 5052, has a Mg content high

enough to be crack resistant. Additionally, the Mg content of

5052 is low enough so that it can be successfully welded

using 4043.

High temperature applications — Al-Mg alloys with Mg

content over 3% are unsuitable for service temperatures over

150°F (65°C) because they are susceptible to stress

corrosion cracking at higher temperatures. This is true for

filler alloys as well and should be taken into account in

selecting filler alloys

5454 — This alloy is a lower Mg alloy specifically developed

to be immune to the stress corrosion cracking noted above.

Filler alloy 5554 is designed as a matching filler alloy for 5454

and should be used whenever possible.

5083 and 5456 — These high Mg, high strength alloys can

be successfully welded using 5356. However, most structural

Codes require that welds in these alloys have a minimum

ultimate tensile strength of 40 ksi (276 MPa). When welded

using 5356, welds in these alloys often will not meet this

requirement. For this reason, 5183 or 5556 are recommend-

ed for these alloys.

6XXX alloys— These Al-Mg-Si alloys are primarily used for

extrusion alloys, although they can also often be found as sheet

and plate. The chemistry of these alloys makes them very sensi-

tive to hot short cracking. Autogenous welds (i.e., welds made

without adding filler metal) will almost always crack. This is why

6061 filler metal does not exist. If it did, welds made using it

would crack. Yet, these alloys are readily weldable using either

4043 or 5356 filler metal. Since the chemistry of 4043, Al with

5% Si, or 5356, Al with 5% Mg, is so different than that of 6061,

when either is mixed with 6061, the result is a weld with a crack

resistant chemistry.

The decision whether to use 4043 or 5356 depends on a

number of factors summarized in Table 6. This table compares

these two common filler metals and shows the advantages and

disadvantages of each.

As shown in Table 6, 4043 is easier for the welder to use, it

flows better, and is more crack resistant. Filler metal 5356 feeds

better and gives welds that are stronger, especially in lap welds

and fillet welds, and are more ductile. While 5356 should be

used to weld the 6XXX alloys to any of the 5XXX alloys, 4043

should be used to weld the 6XXX alloys to the common 3XX.X

casting alloys.

ER4043 ER5356

Smooth Bead, Good Wetting Black Smut, Distinct Ripples

Low Column Strength Best Feedability

Higher Penetration Lower Penetration

Lower Ductility Higher Ductility

Lower Tensile Higher Tensile

Less Prone to Porosity More Prone to Porosity

Anodizes a Dark Grey Anodizes with Good Color Match

Much Lower Shear Strength Higher Shear Strength

Lower Cracking Sensitivity Higher Cracking Sensitivity

Lower Melting Point Higher Melting Point

Narrower Melting Range Wider Melting Range

Table 6 — Comparison of Filler Metals 4043 and 5356

Note: 5356 should be used for applications that will be subsequently

anodized. 5356 will anodize to a color very similar to the parent material.

4043 will turn dark grey on anodizing. Since the 6XXX parent materials

anodize to a clear color, a 4043 weld is very visible and not desirable.

7XXX alloys – Although most of these alloys are not

arc-weldable, 7005, 7003, and 7039, display good weldability.

These alloys should be welded using 5356.

ALUMINUM PRODUCT SELECTION GUIDE

Request publication C8.05 for more information on Lincoln’s

Super Glaze®premium aluminum GMAW wires.

12

www.lincolnelectric.com

Aluminum

1060, 1100, 5086, 6005, 6061 356.0, A356.0, 357.0,

3003, 2219, 3004, 5005, 5052, 5083, 514.0, 5154, Alclad 6061, 354.0 A357.0, 359.0,

Base Metal to Base Metal Alclad 3003 A201.0 Alclad 3004 5050 5652 5456 535.0 5254 5454 6063, 6351 7005 C355.0 443.0 A444.0

356.0, A356.0, 357.0,

A357.0, 359.0, 443.0, 4043 4145 4043 4043 4043 5356 5356 4043 4043 4043 4043 4145 4043

A444.0

354.0, C355.0 4145 4145 4145 4145 4043 NR NR NR 4043 4145 4145 4145

7005 5356 4145 5356 5356 5356 5556 5356 5356 5356 5356 5356

6005, 6061, Alclad 6061, 4043 4145 5356 4043, 5356, 5356 5356 5356 5356 4043,

6063, 6351 5356 4043 5356

5454 4043 4043 5356 5356 5356 5356 5356 5356 5554

5154, 5254 4043 NR 5356 5356 5356 5356 5356 5356

5086, 514.0, 535.0 5356 NR 5356 5356 5356 5356 5356

5083, 5456 5356 NR 5356 5356 5356 5556,

5183

5052, 5653 4043 4043 4043 4043, 5356

5356

5005, 5050 4043 4145 4043 4043,

5356

3004, Alclad 3004 4043 4145 4043

2219, A201.0 4145 2319

1060, 1100, 3003, 1100

Alclad 3003

Notes:

1) The filler alloy shown is the best choice for most structural applications. Where two filler alloys are shown, either are acceptable.

2) Whenever 4043 filler alloy is shown, 4047 is an acceptable alternate.

3) Whenever 5356 filler alloy is shown, 5556 or 5183 are acceptable alternates.

4) Al-Mg alloys containing more than 3% Mg should not be used in applications where long term exposures above 150°F (65°C) are encountered.

5) There are applications where specific requirements make the selection of filler alloys other than those shown above necessary.

Table 7: Aluminum Alloy Filler Metals for Structural Welding of Various Base Aluminum Alloys

13

Aluminum

www.lincolnelectric.com

Welding Preparation

Preparation for welding includes storage and handling of

aluminum prior to welding, methods for making the weld

preparation, and methods for cleaning prior to welding. While

not strictly "welding preparation", methods for backgouging

and interpass cleaning will be included in this section.

Storage of Aluminum and Aluminum Wire

Prior to Welding

Improper storage of aluminum and aluminum wire prior to welding

makes preparation for welding much more costly at best. At

worst, it can result in welds of inadequate quality.

It is well known that all aluminum alloys form a thin oxide coating

immediately upon exposure to air. This coating is extremely thin,

approximately 100–150 Angstroms (one millionth of a centimeter)

thick. Because it is so thin, it is transparent and not visible to the

naked eye. When stored at ambient temperatures and relative

humidity levels of 70% or below, the oxide thickness increases

extremely slowly. It is safe to say that aluminum and aluminum

wires stored under these conditions will be usable for a couple

of years. Plus, the reverse polarity arc tends to strip off the

oxides. Therefore, if aluminum is stored in a dry area, oxide

removal prior to welding will be very easy or unnecessary.

However, if aluminum is subjected to temperatures above 200°F

(93°C) and/or very high humidity levels, the oxide layer thickness

can grow rapidly. Because of this, the following guidelines are

suggested:

• Aluminum plate which has ever become wet should be

scrapped. Boxes of wire where the cardboard box has

become wet on the inside should be discarded.

• Aluminum should never be stored outside.

• Wire should be stored in the original box and any plastic

interior bag it came in.

• It is helpful to store wire in a closed cabinet which is heated to

approximately 20°F (-6°C) above the ambient temperature to

reduce relative humidity. This can be done simply by mounting

an electrical fixture with a low wattage bulb inside the cabinet

and letting the bulb burn continuously.

• Wire which will not be used for 2 days or more should be

dismounted from the wire feeder, returned to its original

packaging, and stored properly.

Aluminum wire which is stored in accordance with the above

recommendations will be usable with no deterioration in

performance for at least 2 years. Wire older than this should

be discarded.

Oxides on aluminum plate can be removed by power wire

brushing, sanding, grinding, or chemical etching, however,

proper storage will prevent the formation of oxides. Aluminum

should be stored indoors in a dry environment. If stored outside,

it should be securely covered to keep it dry. Under no circum-

stances should it be stored uncovered with one plate laying flat

on top of another. This will allow water to “wick” in between the

plates from the edges. If this happens, thick hydrated oxide will

form very quickly on the plate surfaces, making it very difficult to

pry the two plates apart.

Welding Preparation

Even the hardest aluminum alloy is much softer than a high

speed steel or carbide cutting tool. While specialized tools are

available to cut aluminum, aluminum is easily cut using circular

saws, radial arm saws, etc. End preparations can be put on pipe

or tube using woodworking routers. The general rule is "if it will

cut wood, it will cut aluminum".

While aluminum can’t be cut using oxyfuel cutting equipment, it

can be easily cut using plasma cutting equipment. Thin aluminum,

less than 3/16" (4.8 mm) thick, can also be cut by high powered

lasers. However, care must be taken in plasma or laser cutting

of heat-treatable alloys. These alloys are prone to form micro-

cracks which can extend back from the cut edge as far as 1/8"

(3.2 mm). Therefore, laser or plasma cut edges in heat-treatable

alloys are usually machined to remove the edge before welding.

Methods of weld preparation are as follows:

Machining

Machining of weld preparations can be performed using a variety

of tools. Milling machines, bed planers, and shapers are

commonly used with carbide cutting tools. It is recommended

that any machining be performed dry, i.e., without any cutting

lubricants. Lubricants are either oil (hydrocarbon) or water-based.

If lubricants are used, the residue must be removed before

welding. If not removed, excessive porosity will result.

Sawing

Both band and circular saws are commonly used to make weld

preparations. Higher blade speeds and coarser teeth are

required than when cutting steel. Recommended blade surface

speeds are 8000 sfpm for circular saws and 5000 sfpm for band

saws. Band saw blades should have no more than 4 teeth per

inch. If circular saws are used, the cut quality can be good

enough so that no further preparation is necessary. Band saws

usually leave a coarse surface which must be sanded or grinded.

Grinding and Sanding

The use of grinding and/or sanding to form weld preparations

has been discouraged in the past, because organic binders in

the disc often left behind organic residues which then caused

weld porosity. However, there are a number of grinding and

sanding discs available today which are specifically formulated

for aluminum. These can give excellent results for forming weld

preparations on aluminum.

Shearing

Shearing is very useful to cut sheets or plates to size. However,

the edge quality is rarely acceptable for welding. It is relatively

rough and has a lot of crevices which can trap oils, greases, etc.

It is recommended that the edge be smoothed by machining,

grinding, or sanding after shearing.

14

www.lincolnelectric.com

Aluminum

Preweld Cleaning

Once the weld preparation is formed, it must be cleaned before

the weld joint is fit together. Cleaning consists of removing any

contaminants. These contaminants are as follows:

(1) Oils and Greases

Removal of oils and greases can be performed in one of several

ways. First, wiping with a clean rag saturated with a degreasing

solvent. This method is very effective. However, the use of many

solvents has been severely curtailed in recent times because of

environmental concerns. Second, mild alkaline solutions make

good degreasers. The part to be degreased can be sprayed

with these solutions or dipped into a tank containing them.

Since such cleaners are usually water based, it is important to

thoroughly dry the part after degreasing. Third, many suppliers

sell acid based cleaning solutions for cleaning aluminum. These

are usually effective. However, all are acidic and some contain

hydrofluoric acid, so caution in their use and disposal is

required. Again, since they contain water, the piece must be

thoroughly dried before welding.

Whichever method is used, it is important to degrease the part

to be welded before performing any of the oxide removal

procedures outlined below. Otherwise the oils and greases will

be spread by the oxide removal and will be difficult to remove.

(2) Excess Oxides

Once the oils and greases are removed, oxide removal can be

performed in several ways. The most common is to use a

stainless steel wire brush. The brush should be clean and not

previously used on materials other than aluminum. The brush

should be relatively flexible and should be used with only light

pressure in order to avoid unnecessarily roughening the surface

of the aluminum.

Oxide removal can also be performed by immersing the part in a

strong alkaline solution. However, these solutions are very

corrosive, and can etch the surface of the aluminum, therefore,

extreme care must be used.

In some industries, especially the aerospace industry, final oxide

removal is performed just before the joint is fit together by

mechanically removing the oxide using a steel scraper (identical

to those used in woodworking) or by draw filing. Once the

cleaning is performed, the joint is fit together as soon as possible.

These are very effective methods for oxide removal. However,

they are time consuming, costly, and are primarily used in

industries where the demand for extremely high quality overrides

the additional cost.

Interpass Cleaning

The surface of a weld usually has areas of oxides and weld

"smut" on it. This gray to black colored smut is composed of

aluminum oxide and magnesium oxide. Before depositing

another weld pass, it is recommended that the smut and oxides

be removed, because they can cause lack of fusion defects.

The easiest way to remove these oxides is to use a wire brush,

either manual or power driven. The wire brush should be clean

and used only on aluminum. It should be flexible and used with

light pressure.

Backgouging

When making a double-sided weld, it is necessary to remove the

metal on the back side to sound metal before depositing the

back side weld. If this isn’t done and the backside weld is made

with no preparation, lack of fusion will often result.

The usual geometry for the backgouged seam is a V preparation

with a 60° included angle and a 1/8" (3.2 mm) radius at the

base. There are a number of ways to perform this backgouging:

(1) Air Arc or Plasma Arc Gouging

Either of these processes can be used successfully. However,

they rely on the skill and steadiness of the operator to obtain a

uniform backgouge. In addition, they usually require cleaning up

with a grinding disk before welding. This is especially true of air

arc gouging, which leaves carbon deposits in the gouged

groove. If the carbon isn’t removed, porosity on the backside

weld can result.

(2) Grinding

A thin [1/8" (3.2 mm)] grinding disk on edge can be used for

backgouging. Again, the operator must be skilled in order to

produce a uniform gouge.

(3) Machining

Ideally, the best way to get a uniform backgouge is to mount the

weld in a milling machine and machine the backgouge.

Unfortunately, this usually isn’t practical. However, a number of

manufacturers supply a pneumatically powered circular saw

mounting a 4" (102 mm) diameter milling cutter. This milling

cutter is ground to have a tooth form with a 60° V with a 1/8"

(3.2 mm) tip radius. The depth of the backgouge is set by

setting the cutting depth of the saw. It is relatively easy to set up

a straightedge to guide the saw along to get a straight back-

gouge.

(4) Chipping

Although not used very often, the use of a pneumatic chipping

hammer with the appropriate chisel can be a very effective way

to backgouge. The problem with this method is the extremely

high noise level produced. It is very easy to regulate the cutting

depth to get down to sound metal because it is obvious to the

operator when sound metal is reached. The effectiveness of this

method is very dependent on the geometry of the chisel. The

correct geometry is shown in Figure 3.

Figure 3: Correct Pneumatic Chisel Geometry for

Backgouging Aluminum.

15

Aluminum

www.lincolnelectric.com

If available, GMAW-P is able to join thin and thick sections of

aluminum. For those materials that are less than or equal to

0.125" (3.2 mm), pulsed spray transfer is the preferred choice.

Pulsed spray transfer is more easily able to join materials less

than 0.125" (3.2 mm), and this is due to the fact that the

average current is lower in magnitude for GMAW-P than axial

spray transfer welding current. When compared to axial spray

transfer GMAW-P has the following advantages when used for

welding aluminum:

• Lower heat input – less distortion.

• Ability to handle poor fit-up.

• Ability to handle thinner materials.

• The lower heat input of GMAW-P reduces the size of the

heat affected zone.

• Out-of-position welding is greatly enhanced.

Power Supplies and Wire Drives

The history of the development of power sources for aluminum

GMAW welding relates to the development of constant current

(CC), or constant voltage (CV) output characteristics. Prior to the

development of CV power sources the use of CC or "drooper"

type power sources were used exclusively for welding aluminum.

Special techniques were required for arc striking and special

variable speed wire drives were developed as a solution for the

unstable arc length associated with constant current.

Constant current power sources provided excellent penetration

uniformity, and they reacted slowly to changing conditions. The

slower dynamic response to changes in arc length were desirable

for welding thicker sections of aluminum with electrode diameters

3/32" (2.4 mm) and larger. The primary disadvantage of CC

power sources is arc starting and the ability to regulate arc

length.

In the late 1950s, when selenium rectifiers were employed to

provide the CV output characteristics, many aluminum fabrica-

tors soon realized there was a problem. The output of the early

CV power sources produced wide welding current fluctuations

due to changes in arc length, and this was compounded by

changes in output due to fluctuations in input power. Because of

the higher thermal conductivity of aluminum the current changes

that occurred produced variations in weld penetration.

Properties of Aluminum

The engineering use of wrought and cast aluminum base materials

continues to increase, and it does so because of the basic

properties of this unique material. The more prominent features

of aluminum and its alloys are:

• Aluminum is lightweight. It weighs about one third that of

steel. A cubic inch of aluminum weighs 0.098 lbs./in.3com-

pared to steel, which weighs 0.283 lbs/in3.

• Aluminum has a wide range of strength properties that vary

from 13,000 tensile for pure aluminum up to 90,000 tensile for

the heat treatable aluminum alloys.

• Aluminum provides excellent corrosion resistance in many

environments. The thin refractory oxide that forms on the

surface of aluminum provides a protective barrier.

• Aluminum is an excellent conductor of heat. It is up to five

times more thermally conductive than steel.

• Aluminum is reflective of radiant heat, and the surface finish of

aluminum is frequently used to take advantage of this feature.

• Aluminum is widely available in either extruded shapes or

wrought sheet in an equally wide range of alloy compositions.

• Aluminum is widely available as a die cast base material.

For welding purposes, an important consideration for welding

aluminum is its thermal conductivity. This property has an

important facet:

• To compensate for the high rate of thermal conductivity,

aluminum requires the use of higher energy modes of metal

transfer. Axial spray and pulsed spray are the two recom-

mended GMAW modes of metal transfer for aluminum. The

use of the lower energy forms of metal transfer will usually

result in incomplete fusion defects.

Modes of Metal Transfer

What is important to note when welding aluminum base material

is that the thermal conductivity of the aluminum base material is

higher than it is for carbon steel, and because of this the lower

energy modes of metal transfer are unable to provide sufficient

melting of the base material to ensure good fusion.

Axial spray and pulsed spray metal transfers are the preferred

metal transfer modes for aluminum, each of these are capable

of providing the required energy levels for base metal melting to

assure good fusion.

Table 8 supplies the typical axial spray transfer transition

currents related to specific aluminum electrode diameters (note

that argon gas is the shielding gas associated with the transition

currents). In those cases where helium additions are made to

the argon, the required watt energy level (current x voltage) to

achieve the transition to axial spray will have to increase. Axial

spray is the higher energy transfer mode for GMAW, and

aluminum requires the use of higher energy modes of transfer to

compensate for the higher thermal conductivity. Because of

these two central facts, axial spray is generally applied to

aluminum base materials 0.125" (3.2 mm) or greater in material

thickness.

Table 8

Aluminum Electrode

Diameter Shielding Transition

(mm) Inches Gas Current

(0.8) 0.030 100% Argon 90 ± 5 Amps

(0.9) 0.035 100% Argon 110 ± 5 Amps

(1.2) 0.047 100% Argon 135 ± 5 Amps

(1.6) 0.062 100% Argon 180 ± 5 Amps

AXIAL SPRAY TRANSITION CURRENT

GMAW of Aluminum Alloys

16

www.lincolnelectric.com

Aluminum

Incomplete fusion defects often accompanied the penetration

problems. Because of this, many aluminum fabricators went

back to CC power supplies for consistent penetration. As a

result of these early difficulties, much of the available aluminum

welding literature continues to advocate the use of CC supplies.

Constant voltage power supplies produced since the 1990’s

demonstrate more consistent output. These newer CV power

sources are line voltage compensated, which assures consistent

delivery of output. CV enjoys widespread use, and is highly

recommended for aluminum gas metal arc welding.

GMAW-P Power Supplies

Pulsed arc power supplies have become much more sophisti-

cated than those of only a few years ago. Early pulsed power

supplies had a fixed pulsing frequency based upon multiples of

input frequencies, and they usually were 60 and 120Hz. These

systems were non-synergic, and they were difficult to set up.

The 1990’s introduced newer pulsed power sources that provided

synergic control (one knob control) with a high speed amplifier

used to control output. In the newer pulsed arc power sources,

either an inverter transformer or related Chopper Technology®

provide power for the arc, and software is used to direct the

output of the power source.

The software developed specifically for these newer power

sources provides a wide selection for a range of filler types,

diameters, and shielding gas compositions. In most cases the

newer power sources provide a wide selection of pulsed spray

transfer, synergic CV, and special Pulse on Pulse™ programs

for use with aluminum electrodes.

Wire Drives and Controls

Reliable feeding of the softer aluminum solid wire electrodes

through a welding torch presents more of a challenge than

feeding carbon steel electrodes. Aluminum wire is much less

rigid than steel wire and it is harder to push through a GMAW

torch. Special wire drives and GMAW guns are available to

enhance the feedability of aluminum electrode. They fall into four

main categories:

1. Push Type Feeders

Standard wire feeders, employed for carbon steel solid wire

electrodes, can also be referred to as "push type feeders." In

this type of equipment, a spool of wire is mounted on a spindle

located to the rear of the drive. A shielding gas pre-flow and

post-flow timer/control should be available. There is a set of

drive rolls (two-roll or four-roll), on the feeder which pushes the

wire through from the spool mounting device through the torch

cable and then through the contact tip.

For aluminum electrode, the use of highly polished "U"

groove drive rolls, is recommended. In all of the ensuing

scenarios the use of hard shell nylon or Teflon type liners is

strongly recommended. This type of system, with some modifi-

cations described below, can also be used to feed softer

aluminum wire under the following circumstances:

• The gun cable must be kept short, 10-12 ft. (3.0-3.6 m) is the

practical maximum length. The shorter the GMAW gun cable,

the better the overall performance. Teflon or hard shelled

nylon electrode liners must also be employed.

• If 1/16" (1.6 mm) diameter wire is used, either 4043 or 5356

filler alloys can be pushed. The thicker electrodes have higher

column strength. Again, Teflon or hard shell nylon electrode

liners must be employed.

• 3/64" (1.2 mm) 5356 filler metal can generally be pushed, but

3/64" (1.2 mm) 4043 filler metal will usually result in wire

feeding problems if pushed.

• Plastic or aluminum specific inlet and outlet guides and

special aluminum contact tips are also recommended.

• U-grooved type drive rolls should be used.

2. Push–Pull Type Feeders

A solution to the problem of feeding either small diameter or

softer aluminum wire is to use a "push–pull" feeder. In most

push-pull feeders, the pull motor in the welding torch is the

“master” motor and the push motor in the cabinet is the “slave”

motor.

Wire feed speed is controlled by the motor on the torch handle,

and the cabinet contains a motor system designed to provide a

slack wire reducing effect on the electrode. This push-pull type

of aluminum wire drive system provides the most consistent

daily performance when compared to the other type systems.

Figure 4 shows a complete push-pull system. Figure 5, on the

following page, shows the welding torch up close.

The push-pull systems handle aluminum diameters from 0.030"

to 1/16" (0.8 - 1.6 mm). They reliably feed aluminum wire up to

50 ft. (15.2 m) from the control cabinet.

Figure 4: Complete Push-Pull Drive System:

Power Wave® 355M power source, combined with the

Power Feed™ 10M wire feeder and push-pull aluminum torch.

For more information on this system, request

publications E5.146 and E8.267.

17

Aluminum

www.lincolnelectric.com

3. Push–Pull GMAW Torches

Figure 5 shows a closeup of a push-pull aluminum torch. The

bulged area of the gun handle houses the pull drive motor. This

permits the use of a more integrated approach for feeding

aluminum. The motor in the torch handle is variable torque —

constant speed, which permits the use of the wire feed speed

control at the wire feeder.

There are several “after market” add–on welding torches

available that can convert most wire feeders to push-pull. These

add-on welding torches usually function such that the pull torch

in the gun is the “slave” and the push motor in the wire feeder is

the “master”.

There is evidence that the more commonly used gun (master)

and feeder (slave) arrangement gives more consistent results,

but these add–on pull torches have also been shown to be

effective.

Both push and push-pull welding torches are available in air-

cooled and water-cooled versions. Even the largest air-cooled

torches are typically rated at 200 amps maximum at 60% duty

cycle for aluminum. It is recommended that water-cooled

torches be used for high-volume production or whenever

currents over 150 amps will be used.

Welding torches are available in straight barrel pistol grip, curved

barrel pistol grip or gooseneck styles. All are acceptable for

welding aluminum, however, if curved barrels are used, avoid

sharply bent barrels — they will add to wire feeding difficulties.

4. Spool Guns

Another solution for light duty aluminum welding is the spool gun

shown in Figure 6. In this system, a 1 lb. (0.5 kg) spool of filler

wire is mounted directly on the rear of the GMAW gun, so that it

is only pushed a few inches past the drive rolls, show in inset.

These spool guns are usually air-cooled and rated for 200 Amps

maximum at 60% duty cycle, so they are not recommended for

high current or high duty cycle welding.

Aluminum Feeding Enhancements

• Drive Rolls should always be highly polished "U" groove type

for aluminum. The “U" groove is designed to cradle the softer

electrode without altering its shape and the high polish prevents

the accumulation of aluminum oxide in the drive roll groove.

Steel electrodes use either knurled rolls or a "V" groove

configuration. Drive rolls designed for carbon steel electrodes

should not be used for feeding aluminum.

• Inlet and outlet wire guides for feeding aluminum should be

made from teflon, nylon, or other suitable plastic which will not

scrape the wire. A typical wire guide for aluminum is shown in

Figure 7. Wire guides for steel wire are usually made from

steel and should not be used to feed aluminum.

• Torch liners for aluminum welding should be either teflon,

nylon or other plastic liner material. Some of these types of

aluminum liners will have a short coiled brass liner section

located at the front of the plastic liner. Liners for torches made

to feed steel are usually made from spirally wound small

diameter steel wire. These types of liners should not be used

for feeding aluminum. They will shave the aluminum wire and

then quickly clog the path.

• Most manufacturers make contact tips specifically for

aluminum wire. Aluminum readily expands as it absorbs the

heat of the arc. Aluminum contact tips for a given size

aluminum wire are designed to accommodate the thermal

expansion of the wire — the inside diameter of the contact tip

is slightly larger than those for the same size steel wire.

Contact tips for welding steel are not suitable for welding

aluminum.

Some welders, after encountering aluminum feeding problems,

opt to use oversize contact tips, ie., 1/16” (1.6 mm) tips on

3/64” (1.2 mm) wire. This is usually unacceptable. The contact

tip must transfer current to the wire. An oversized tip will not

allow consistent current transfer. Arcing in the tip will occur

which will produce sharp burrs on the bore of the tip.

Another unacceptable practice is to use a wire straightener

and tighten it down hard so that all of the cast is removed

from the wire. Because the wire needs cast to make proper

contact in the tip, removing all of the cast usually results in

burnback.

• The contact tip should be flush with the end of the gas nozzle

or slightly recessed [approximately 1/8” (3.2 mm)]. The tip

should not extend past the gas nozzle.

Figure 5: Push-Pull GMAW Aluminum Torch

Figure 7: Drive Rolls and Wire Guide for Feeding Aluminum

Figure 6: Magnum® 250LX Spool Gun

For more information, request publication E12.25.

18

www.lincolnelectric.com

Aluminum

Shielding Gas

The recommended shielding gas for welding aluminum up to

approximately 1/2" (12.7 mm) in thickness is 100% argon.

Above this thickness, where additional energy is needed to melt

the material, it is common to use gas mixtures of 75% argon +

25% helium or 75% helium + 25% argon. The use of helium in

the arc provides additional energy used to accommodate heavier

section thickness welding. It also expands the cross sectional

shape of the finished weld giving it a more rounded appearance.

Shielding gas flow rates range from 30 to 100 cubic feet/hour

(cfh), (14 to 47 L/min). Higher flow rates are employed for wider

diameter gas nozzles and when using higher helium two-part

blends.

Shielding gas components such as oxygen, hydrogen, or CO2

should never be employed for aluminum GMAW. Even in trace

amounts these gases will adversely affect the weld.

Welding Techniques

The formation of black soot on the surface, or the adjacent

areas of a weld, is referred to as smut. It is made up of finely

divided oxides of aluminum and magnesium. They usually

indicate that adjustments in technique are necessary.

At the onset of learning to weld using aluminum GMAW, the

most common mistake made is to hold too long a contact tip to

work distance (CTWD). Shorter CTWD’s, 1/2" to 5/8"

(12.7 - 15.8 mm), are required when welding aluminum. If the

CTWD is too long, then the gas shielding will be insufficient. In

the absence of adequate shielding gas the weld will become

gray, and in the most severe case, the arc may bore into the

work piece.

At the start of an aluminum weld, it is not uncommon to get a

cold looking weld bead for the first 1/2" (12.7 mm). This is due

to the high thermal conductivity of aluminum. This condition can

be minimized by using a power supply with a hot start. A common

alternative used in the absence of a hot start control is to strike

the arc about 1" (25.4 mm) ahead of the nominal weld starting

point, and quickly maneuver the arc back to the desired starting

point. This action has the effect of providing preheat to the

aluminum base material, and it provides improved fusion at the

beginning of the weld.

While welding, the torch must be held with a push angle of 5° to

10° (also known as a leading torch angle). If the torch is applied

using a drag angle (also known as a lagging torch angle), then

the gas shielding will be absent from the molten puddle and the

finished weld will appear gray or black.

Care must be taken in extinguishing the arc. Terminating the arc

abruptly will result in a deep weld crater that may contain a

shrinkage crack in the crater. There are a number of ways to

minimize the size and depth of the crater.

• Weld tabs can be used and the weld may be started and

terminated on them.

• A power supply with an arc decay control allows the electrode

and current to tail off for a predetermined wire feed speed per

unit of time. This permits a controlled fill of the aluminum weld

crater.

• Near the end of the weld, progressively increase the travel

speed. The effect here is to reduce the size of the weld bead

and diminish the overall size of the crater. This is known as a

"feathering” or “back step” technique.

• At the end of the weld, reverse the direction of the torch to

place the crater within the body of the weld bead.

Some welders learn aluminum GMAW by keeping a very steady,

constant motion in the travel direction to make a very smooth

weld with a minimum of weld ripples. This is known as a straight

progression type weld bead, see Figure 8. Other welders learn

to weld by using the back step technique, see Figure 9. Each of

these techniques produce a weld with distinct, evenly spaced

ripples. Each technique produces acceptable finished welds.

The finished weld should be bright and free from oxides and

smut. A "frost line" or cleaning stripe approximately 1/16" to 1/8"

(1.6 to 3.2 mm) wide should be visible along each edge of the

weld. These stripes show the area where the reverse polarity arc

has removed the oxide from the aluminum surface. If the weld

metal is black or gray, or if the cleaning stripes are not present,

something is wrong. The most likely causes are either the arc

length is too long or the torch angle is wrong. If some weld smut

is present outside these areas - this is expected. There will also

be some weld smut present at weld starts, stops and at internal

and external corners. More smut will be present when using

5XXX filler than with 4XXX filler.

Figure 9: A Back Step Technique Weld

Figure 8: Straight Progession Weld

19

Aluminum

www.lincolnelectric.com

Figure 10: Radiograph Showing a Crater Crack

Weld Defects — Causes and Cures

Some weld defects — or discontinuities — may be small enough

that they don’t seriously impair the mechanical properties of the

weld joint. Other discontinuities may cause immediate joint failure.

The effects of other discontinuities may be more insidious. It is

not the purpose of this section to assess the acceptability or

rejectability of specific discontinuities. Instead, the appearance

of the various types of weld defects will be illustrated and

methods to eliminate or minimize these defects.

Cracking

Cracking occurs when a combination of a susceptible

microstructure or chemistry and a sufficiently high solidification

stress are present. If you reduce the stress or change the

microstructure or chemistry, the cracking can be eliminated.

All weld cracking in aluminum is caused by hot cracking.

That is, it takes place during weld solidification.

Crater Cracking

If the arc is extinguished rapidly, there isn’t enough filler metal

present to avoid forming a deep "crater". The geometry of the

crater locally intensifies the solidification stresses. If they are high

enough, a crack forms in and around the crater.

In order to eliminate crater cracking, the geometric discontinuity

of the crater must be minimized, i.e., the crater must be filled in

as much as possible. There are several methods to prevent

crater cracking:

• Use a power supply with a crater fill option.

• Rapidly restrike and extinguish the arc a few times while

keeping the wire tip in the crater. This will build up the crater.

• Run the weld bead to the end of the workpiece, then reverse

direction and increase travel speed in the new travel direction.

Figure 11: Radiograph Showing Longitudinal Weld Cracking

Longitudinal Cracking

Longitudinal cracking occurs relatively frequently. A radiograph

of a longitudinal weld crack is shown in Figure 11.

Weld cracking can usually be eliminated by taking following

precautions:

• Heat treatable alloys are crack sensitive and will crack if

welded autogenously. Make sure you add filler metal.

• Make sure you add enough filler metal in welding any alloy. Do

not deposit thin, concave groove welds or small or concave

fillets. They may crack. Weld passes in both groove welds and

fillet welds should be convex.

• If cracking is encountered in making a square butt weld, try

a V-weld preparation. It will allow the addition of more filler

metal. Similarly, if you’re using a bevel prep, go to a V-prep.

• Reduce the clamping pressure to allow the material to move

slightly during solidification. Occasionally high stress is caused

by the joint geometry, which may need to be changed.

Liquation Cracking

Liquation cracking is common in lap and fillet welds in thin heat-

treatable alloys. It usually is not seen in the nonheat-treatable

alloys or in butt joints. It manifests itself as a short longitudinal

crack in the parent material on the back side of a weld. It is

caused by the melting of low melting point compounds which

tend to segregate to the grain boundaries in heat-treatable

alloys. In order to minimize it, weld penetration into the parent

metal needs to be controlled in lap and fillet welds. Welds having

30 or 40% penetration into the parent metal will almost never

cause a crack, while welds penetrating 70 – 80% into the parent

metal will often cause a small crack on the back side of a weld.

20

www.lincolnelectric.com

Aluminum

Incomplete Penetration

A radiograph of a weld showing incomplete penetration is

shown in Figure 12. Incomplete penetration is often caused by

insufficient weld current at a welding travel speed that is too

high. However the use of an arc voltage that is too high can also

result in the arc bridging the weld root and not penetrating

completely.

Care must also be taken in backgouging a two–sided weld.

Insufficient backgouging can sometimes result in incomplete

penetration. It is sometimes surprising how deep the backgouge

must be to get to sound metal.

Figure 12: Radiograph Showing Incomplete Penetration

Figure 13: Fracture Surface of a Weld with Incomplete Fusion

Figure 14: Fracture Surface of a Weld with Excessive Porosity

Figure 15: Radiograph Showing Copper Contamination

(Copper contamination shows up as lighter and irregularly shaped areas.)

Incomplete Fusion

Incomplete fusion, Figure 13, is usually caused by welding over

heavy oxides, insufficient interpass cleaning, or poor bead place-

ment. Heavy oxides must be removed before welding. The weld

smut and/or oxides must be removed before making another

weld pass.

Porosity

Figure 14 shows excessive porosity in a fracture surface of a

weld. Porosity in aluminum welds is caused by bubbles of

hydrogen gas which are trapped in the welds as it cools. It has

already been discussed that the source of this hydrogen is oils,

greases, or water vapor that is dissociated by the welding arc.

In order to control weld porosity, the sources of these

contaminates must be eliminated. It is also helpful when welding

in the vertical position, to use an upward progression, rather

than the downward progression usually used to weld steel, to

minimize weld porosity.

Copper Contamination

Copper contamination will also appear white on a radiograph, as

seen in Figure 15. Copper contamination is usually larger and

"fuzzier" than tungsten, which appears as individual small

particles.

Copper contamination is often encountered in GMAW and is

caused when the wire burns back and fuses to the copper

contact tip. The copper and aluminum quickly alloy and deposit

copper in the aluminum weld. If this occurs, the copper

contamination must be ground out and repaired because the

aluminum/copper alloy that is deposited is very brittle.

Copper contamination can also be caused by copper backing

bars or copper tooling. While the use of copper backing bars is

acceptable, the joint preparation must be such that the arc is

not allowed to impinge directly on the copper bar. If it does, the

copper bar will melt and alloy with the aluminum. While copper

backing bars are acceptable, wide root openings must be

avoided.

21

Aluminum

www.lincolnelectric.com

Solving Problems in Qualifying Weld Procedures

Many fabricators encounter difficulties in qualifying welding

procedures or welders for aluminum. Most codes require the

use of reduced section tensile tests and guided bend tests for

procedure qualification. Therefore, we will discuss these two

requirements:

Difficulties in Meeting Tensile Test Requirements

All codes have minimum tensile test values. Samples removed

from procedure qualification test plates must meet these values.

However, the weld does not have to meet the same minimum

requirements as the parent material. For example, all codes

require that 6061–T6 material have a minimum tensile strength

of 40 ksi (276 MPa). Welds in 6061–T6 only have to meet 24 ksi

(165 MPa) minimum. It is important to understand what is

required for the specific alloy being used.

There are several reasons why samples fail tensile testing. For

heat-treatable alloys, usually it is because excessive heat input

has been used. Common reasons for excessive heat input are:

• Use of excessive preheat. Preheat should be no more than

200°F (93°C) and isn’t needed unless the ambient

temperature is below 32°F (0°C).

• Interpass temperature that is too high. Maximum interpass

temperature should be 250°F (121°C).

• Technique issues, such as the use of very wide weave

passes, which can cause heat input to be excessive.

Generally stringer passes should be used, although weaving

is acceptable as long as the weave width is no wider than

four times the wire diameter.

Weld defects can also cause premature tensile failures. Observe

the fracture face of the failed tensile sample. The presence of

weld defects should be fairly obvious. Lack of fusion or lack of

penetration defects are especially prone to cause tensile failure.

Where the code requires the tensile sample to meet 40 ksi

(276 MPa) minimum tensile strength, the use of 5356 is not

recommended. Higher strength filler alloys, such as 5183 or

5556, are recommended for these applications.

Difficulties in Meeting Bend Test Requirements

Most bend test failures are caused by the welder’s lack of

familiarity with the bend test requirements for aluminum welds.

Some points to remember are as follows:

1. The ductility of aluminum welds is lower than that of steel

welds. Ensure the test radius is correct for the alloy under

test. Figure 16, on the following page, shows the bend test

requirements of AWS D1.2.

2. If the bend sample fails with little or no distortion before

breaking, the most likely cause is a defect in the weld. Any

lack of fusion or insufficient penetration in the weld will

quickly open up on bending and cause the sample to break

in half. A visual examination of the fracture surface will reveal

these defects.

3. Ensure that the bend test sample preparation is correct.

a. Make sure grinding or machining marks go along the

length of the sample, not across it. Marks going across

the sample can act as crack initiation sites.

b. Don’t leave square-machined corners on the sample. All

codes allow a radius at the corners of 1/2 the sample

thickness or 1/4” (6.4 mm) , whichever is less. Adhering to

this radius reduces the probability of initiating a crack in the

corners.

4. Special precautions are necessary when testing welds in

6061 or other M23 (per AWS) or P23 (per ASME Section IX)

materials because of their limited ductility. In recognition of

this, both AWS D1.2 and ASME Section IX require bend test

samples in 6061 and other M23 materials to be machined to

1/8" (3.2 mm) thickness, instead of the normal 3/8" (9.5 mm)

thickness. If 6061 samples are machined to 3/8" (9.5 mm)

thickness and tested around a standard radius mandrel,

they often fail. AWS D1.2 alternatively allows samples in M23

materials to be machined to 3/8" (9.5 mm) thick and

annealed before testing, but ASME Section IX has no such

provision.

5. The use of the standard plunger-type bend tester is respon-

sible for most bend test failures. This test fixture works well

for steel because the mechanical properties of the weld,

HAZ, and parent material are all similar. However, in aluminum,

the HAZs are usually much weaker than the remainder of the

sample. If the sample is tested in a plunger–type tester, the

bend strain is concentrated in the HAZ. Instead of bending

smoothly around the mandrel, the sample often forms a

sharp kink at the HAZ and the sample fails at the kink.

A much better test for welded aluminum bend samples is the

Wraparound Guided Bend Test, shown in Figure 17, on the

following page. In this test, the sample is pulled around the

mandrel and forced to stay in contact with it. These test jigs

are often made from rotary tubing benders. Both AWS D1.2

and ASME Section IX encourage the use of these testers for

aluminum.

22

www.lincolnelectric.com

Aluminum

Figure 16: Bend Test Requirements from AWS D1.2 using Plunger Type Tester

Figure 17: Bend Test Requirements for Wraparound Bend Test Fixture

Thickness of

Specimen (Inches) A (Inches) B (Inches) C (Inches) D (Inches) Materials

3/8 1-1/2 3/4 2-3/8 1-3/16 M21 and M22

t 4t 2t 6t + 1/8 3t + 1/16

1/8 2-1/16 1-1/32 2-3/8 1-3/16 M23 and F23

t (<1/8) 16-1/2t 8-1/4t 18-1/2t + 1/16 9-1/4t + 1/32 Welds

3/8 2-1/2 1-1/4 3-3/8 1-11/16 M25 and

t 6-2/3t 3-1/3t 8-2/3t + 1/8 4-1/3t + 1/16 Annealed M23

3/8 3 1-1/2 3-7/8 1-15/16 M27 and

t 8t 4t 10t + 1/8 5t + 1/16 Annealed M24

Thickness of

Specimen

Inches A (Inches) B (Inches) Materials

3/8 1-1/2 3/4 M21 and M22

t4t 2t

1/8 2-1/16 1-1/32 M23 and F23

t (<1/8) 16-1/2t 8-1/4t Welds

3/8 2-1/2 1-1/4 M25 and

t 6-2/3t 3-1/3t Annealed M23

3/8 3 1-1/2 M27 and

t 8t 4t Annealed M24

Notes:

1. Dimensions not shown are the option of the designer. The essential consideration

is to have adequate rigidity so that the jig parts will not springs.

2. The specimen shall be firmly clamped on one end so that there is no sliding of the

specimen during the bending operation.

3. Test specimens shall be removed from the jig when the outer roll has been

removed 180° from the starting point.

NOTE: All dimensions in Inches

23

Aluminum

www.lincolnelectric.com

16

14

12

10

8

6

4

2

00

1

2

3

4

5

7

6

0 5 10 15 20

0 100 200 300 400 500 600 700 800 900

0.030 in. (0.8 mm)

0.035 in. (0.9 mm)

0.045 in. (1.2 mm)

0.062 in. (1.6 mm)

0.093 in. (2.4 mm)

Wire feed speed, inches per minute

Wire feed speed, meters per minute

Melting rate, lb/h

Melting rate, kg/h

800

700

600

500

400

300

200

100

00

5

20

15

10

0 50 100 150 200 250 300 350 400

Welding current A (DCEP)

Wire feed speed, inches per minute

Wire feed s

p

eed, meters

p

er minute

0.030 in. (0.8 mm)

0.035 in. (0.9 mm)

0.045 in. (1.2 mm)

0.062 in. (1.6 mm)

0.093 in. (2.4 mm)

450

Welding Current vs WFS for ER4043 Aluminum Electrodes

at a Fixed Stickout

Typical Melting Rates for Aluminum Electrodes

General Welding Guidelines

Welding Current vs WFS for ER5356 Aluminum Electrodes

at a Fixed Stickout

800

700

600

500

400

300

200

100

00

5

20

15

10

0 50 100 150 200 250 300 350 400

Welding current A (DCEP)

Wire feed speed, inches per minute

Wire feed speed, meters per minute

0.030 in. (0.8 mm)

0.035 in. (0.9 mm)

0.045 in. (1.2 mm)

0.062 in. (1.6 mm)

0.093 in. (2.4 mm)

450

24

www.lincolnelectric.com

Aluminum

Welding Joint Designs for Aluminum GMAW

Groove Welding — Flat, Horizontal, Vertical and Overhead

25

Aluminum

www.lincolnelectric.com

Welding Guidelines for Aluminum GMAW

Groove Welding — Flat, Horizontal, Vertical and Overhead

Welding Argon Travel Approx.

Joint Electrode Current(3) Arc Gas Flow Speed Electrode

Plate Weld Edge Spacing Weld Diameter (Amps) Voltage(3) CFH ipm Consump.

Thickness Position(1) Prep (2) In. (mm) Passes In. (mm) (DC+) (Volts) (L/min.) (M/min.) (lbs/100 ft)

1/16” F A None 1 0.030 (0.8) 70-110 15-20 25 25 - 45 1.5

(2 mm) (12) (0.64 - 1.14)

F G 3/32 (2.4) 1 0.030 (0.8) 70-110 15-20 25 25 - 45 2

(12) (0.64 - 1.14)

3/32” F A None 1 0.030-3/64 90-150 18-22 30 25 - 45 1.8

(2 mm) (0.8 - 1.2) (14) (0.64 - 1.14)

F, V, H, O G 1/8 (3.2) 1 0.030 (0.8) 110-130 18-23 30 25 - 30 2

(14) (0.64 - 0.76)

1/8” F, V, H A 0 - 3/32 10.030 - 3/64 120-150 20-24 30 24 - 30 2

(3 mm) (0 - 2.4) (0.8 - 1.2) (14) (0.60 - 0.76)

F, V, H, O G 3/16 (4.8) 1 0.030 - 3/64 110-135 19-23 30 18 - 28 3

(0.8 - 1.2) (14) (0.45 - 0.71)

3/16” F, V, H B 0 - 1/16 1F, 1R 0.030 - 3/64 130-175 22-26 35 24 - 30 4

(5 mm) (0 - 1.6) (0.8 - 1.2) (16) (0.60 - 0.76)

F, V, H F 0-1/16 13/64 140-180 23-27 35 24 - 30 5

(0 - 1.6) (1.2) (16) (0.60 - 0.76)

OF0-1/16 2F 3/64 140-175 23-27 60 24 - 30 5

(0 - 1.6) (1.2) (28) (0.60 - 0.76)

F, V H 3/32 - 3/16 23/64 - 1/16 140-185 23-27 35 24 - 30 8

(2.4 - 4.8) (1.2 - 1.6) (16) (0.60 - 0.76)

H, O H 3/16 33/64 130-175 23-27 60 25 - 35 10

(4.8) (1.2) (28) (0.63 - 0.89)

1/4” FB

0 - 3/32 1F, 1R 3/64-1/16 175-200 24-28 40 24 - 30 6

(6 mm) (0 - 2.4) (1.2 - 1.6) (19) (0.60 - 0.76)

FF

0 - 3/32 23/64-1/16 185-225 24-29 40 24 - 30 8

(0 - 2.4) (1.2 - 1.6) (19) (0.60 - 0.76)

V, H F 0 - 3/32 3F, 1R 3/64 165-190 25-29 45 25 - 35 10

(0 - 2.4) (1.2) (21) (0.63 - 0.89)

OF

0 - 3/32 3F, 1R 3/64, 1/16 180-200 25-29 60 25 - 35 10

(0 - 2.4) (1.2 - 1.6) (28) (0.63 - 0.89)

F, V H 1/8 - 1/4 2 - 3 3/64-1/16 175-225 25-29 40 24 - 30 12

(3.2 - 6.4) (1.2 - 1.6) (19) (0.60 - 0.76)

O, H H 1/4 4 - 6 3/64-1/16 170-200 25-29 60 25 - 40 12

(6.4) (1.2 - 1.6) (28) (0.63 - 1.02)

3/8” F C - 90° 0 - 3/32 1F, 1R 1/16 225-290 26-29 50 20 - 30 16

(10 mm) (0 - 2.4) (1.6) (24) (0.51 - 0.76)

FF

0 - 3/32 2F, 1R 1/16 210-275 26-29 50 24 - 35 18

(0 - 2.4) (1.6) (24) (0.60 -0.89)

V, H F 0 - 3/32 3F, 1R 1/16 190-220 26-29 55 24 - 30 20

(0 - 2.4) (1.6) (26) (0.60 - 0.76)

OF

0 - 3/32 5F, 1R 1/16 200-250 26-29 80 25 - 40 20

(0 - 2.4) (1.6) (38) (0.63 - 1.02)

F, V H 1/4 - 3/8 41/16 210-290 26-29 50 24 - 30 35

(6.4 - 9.5) (1.6) (24) (0.60 - 0.76)

O, H H 3/8 8 - 10 1/16 190-260 26-29 80 25-40 50

(9.5) (1.6) (38) (0.63 - 1.02)

3/4” F C-60° 0 - 3/32 3F, 1R 3/32 340-400 26-31 60 14 - 20 50

(19 mm) (0 - 2.4) (2.4) (28) (0.36 - 0.51)

FF

0 - 1/8 4F, 1R 3/32 325-375 26-31 60 16 - 20 70

(0 - 3.2) (2.4) (28) (0.41 - 0.76)

V, H, O F 0 - 1/16 8F, 1R 1/16 240-300 26-30 80 24 - 30 75

(0 - 1.6) (1.6) (38) (0.60 - 0.76)

FE

0 - 1/16 3F, 3R 1/16 270-330 26-30 60 16 - 24 70

(0 - 1.6) (1.6) (28) (0.41 - 0.61)

V, H, O E 0 - 1/16 6F, 6R 1/16 230-280 26-30 80 16 - 24 75

(0 - 1.6) (1.6) (38) (0.41 - 0.61)

(1) F = Flat; V = Vertical; H = Horizontal; O = Overhead. (2) See joint designs on page 24. (3) For 5xxx series electrodes, use a welding current in the high side of the range

and an arc voltage in the lower portion of the range. 1XXX, 2XXX and 4XXX series electrodes would use the lower currents and higher arc voltages.

26

www.lincolnelectric.com

Aluminum

Welding Guidelines for Aluminum GMAW

Fillet and Lap Welding — Flat, Horizontal, Vertical and Overhead

Welding Argon Approx.

Electrode Current(4) Arc Gas Flow Travel Speed Electrode

Plate Weld Weld Diameter (Amps) Voltage(4) CFH ipm Consump.

Thickness(1) Position(2) Passes(3) In. (mm) (DC+) (Volts) (L/min.) (M/min.) (lbs/100 ft)

3/32” F, V, H, O 1 0.030 100-130 18-22 30 24 - 30 1.8

(2 mm) (0.8) (14) (0.60 - 0.76)

1/8” F1

0.030 - 3/64 125-150 20-24 30 24 - 30 2

(3 mm) (0.8 - 1.2) (14) (0.60 - 0.76)

V, H 1 0.030 110-130 19-23 30 24 - 30 2

(0.8) (14) (0.60 - 0.76)

O1

0.030 - 3/64 115-140 20-24 40 24 - 30 2

(0.8 - 1.2) (19) (0.60 - 0.76)

3/16” F1

3/64 180-210 22-26 30 24 - 30 4.5

(5 mm) (1.2) (14) (0.60 - 0.76)

V, H 1 0.030 - 3/64 130-175 21-25 35 24 - 30 4.5

(0.8 - 1.2) (16) (0.60 - 0.76)

O1

0.030 - 3/64 130-190 22-26 45 24 - 30 4.5

(0.8 - 1.2) (21) (0.60 - 0.76)

1/4” F1

3/64 - 1/16 170-240 24-28 40 24 - 30 7

(6 mm) (1.2 - 1.6) (19) (0.60 - 0.76)

V, H 1 3/64 170-210 23-27 45 24 - 30 7

(1.2) (21) (0.60 - 0.76)

O1

3/64 - 1/16 190-220 24-28 60 24 - 30 7

(1.2 - 1.6) (28) (0.60 - 0.76)

3/8 F1

1/16 240-300 26-29 50 18 - 25 17

(10 mm) (1.6) (24) (0.46 - 0.64)

H, V 3 1/16 190-240 24-27 60 24 - 30 17

(1.6) (28) (0.60 - 0.76)

O3

1/16 200-240 25-28 85 24 - 30 17

(1.6) (40) (0.60 - 0.76)

3/4 F4

3/32 360-380 26-30 60 18 - 25 66

(19 mm) (2.4) (28) (0.46 - 0.64)

H, V 4-6 1/16 260-310 25-29 70 24 - 30 66

(1.6) (33) (0.60 - 0.76)

O10

1/16 275-310 25-29 85 24 - 30 66

(1.6) (40) (0.60 - 0.76)

(1) Metal thickness of 3/4” or greater for fillet welds sometimes employ a double vee bevel of 50° or greater included vee with 3/32” to 1/8” land thickness on the abutting

member. (2) F = Flat; V = Vertical; H = Horizontal; O = Overhead. (3) Number of weld passes and electrode consumption given for weld on one side only. (4) For 5xxx

series electrodes, use a welding current in the high side of the range and an arc voltage in the lower portion of the range. 1xxx, 2xxx and 4xxx series electrodes would use

the lower currents and higher arc voltages.

27

Aluminum

www.lincolnelectric.com

Introduction. The general subject of safety and safety practices in

welding, cutting, and allied processes is covered in ANSI Z49.18,

“Safety in Welding and Cutting,” and ANSI Z49.29. “Fire Prevention

in the Use of Welding and Cutting Processes.” The handling of

compressed gases is covered in CGA P-110.

Personnel should be familiar with the safe practices discussed in

these documents, equipment operating manuals, and Material Safety

Data Sheets (MSDS) for consumables.

In addition to the hazards discussed in the Arc Welding Safety

Precautions following this section, be familiar with the safety con-

cerns discussed below.

Safe Handling of Shielding Gas Cylinders and Regulators.

Compressed gas cylinders should be handled carefully and should be

adequately secured when in use. Knocks, falls, or rough handling

may damage cylinders, valves, or fuse plugs and cause leakage or

accident. Valve protecting caps, when supplied, should be kept in

place (handtight) until the connecting of container equipment.

Cylinder Use. The following should be observed when setting up

and using cylinders of shielding gas:

1. Properly secure the cylinder.

2. Before connecting a regulator to the cylinder valve, the valve

should momentarily be slightly opened and closed immediately

(opening) to clear the valve of dust or dirt that otherwise might

enter the regulator. The valve operator should stand to one side of

the regulator gauges, never in front of them.

3. After the regulator is attached, the adjusting screw should be

released by turning it counter-clockwise. The cylinder valve

should then be opened slowly to prevent a too-rapid surge of high

pressure gas into the regulator.

4. The source of the gas supply (i.e., the cylinder valve) should be

shut off if it is to be left unattended.

Gases. The major toxic gases associated with GMAW welding are

ozone, nitrogen dioxide, and carbon monoxide. Phosgene gas could

also be present as a result of thermal or ultraviolet decomposition of

chlorinated hydrocarbon cleaning agents located in the vicinity of

welding operations, such as trichlorethylene and perchlorethylene.

DEGREASING OR OTHER CLEANING OPERATIONS

INVOLVING CHLORINATED HYDROCARBONS SHOULD BE

SO LOCATED THAT VAPORS FROM THESE OPERATIONS

CANNOT BE REACHED BY RADIATION FROM THE WELD-

ING ARC.

Ozone. The ultraviolet light emitted by the GMAW arc acts on the

oxygen in the surrounding atmosphere to produce ozone, the amount

of which will depend upon the intensity and the wave length of the

ultraviolet energy, the humidity, the amount of screening afforded by

any welding fumes, and other factors. The ozone concentration will

generally be increased with an increase in welding current, with the

use of argon as the shielding gas, and when welding highly reflective

metals. If the ozone cannot be reduced to a safe level by ventilation

or process variations, it will be necessary to supply fresh air to the

welder either with an air supplied respirator or by other means.

Nitrogen Dioxide. Some test results show that high concentra-tions

of nitrogen dioxide are found only within 6 in. (152 mm) of the arc.

With normal natural ventilation, these concentrations are quickly

reduced to safe levels in the welder’s breathing zone, so long as the

welder keeps his head out of the plume of fumes (and thus out of the

plume of welding-generated gases). Nitrogen dioxide is not thought

to be a hazard in GMAW.

Carbon Monoxide. CO shielding used with the GMAW process will

be dissociated by the heat of the arc to form carbon monoxide. Only

a small amount of carbon monoxide is created by the welding process,

although relatively high concentrations are formed temporarily in the

plume of fumes. However, the hot carbon monoxide oxidizes to CO

so that the concentrations of carbon monoxide become insignificant

at distances of more than 3 or 4 in. (76 or 102 mm) from the welding

plume.

Under normal welding conditions there should be no hazard from

this source. When the welder must work with his head over the weld-

ing arc, or with the natural ventilation moving the plume of fumes

towards his breathing zone, or where welding is performed in a con-

fined space, ventilation adequate to deflect the plume or remove the

fumes and gases must be provided. Because shielding gases can dis-

place air, use special care to insure that breathing air is safe when

welding in a confined space. (See ANSI Z49.1.)

Metal Fumes. The welding fumes generated by GMAW can be con-

trolled by general ventilation, local exhaust ventilation, or by respira-

tory protective equipment as described in ANSI Z49.1. The method

of ventilation required to keep the level of toxic substances within

the welder’s breathing zone below acceptable concentrations is

directly dependent upon a number of factors. Among these are the

material being welded, the size of the work area, and the degree of the

confinement or obstruction to normal air movement where the welding

is being done. Each operation should be evaluated on an individual

basis in order to determine what will be required. Exposure limits for

toxic substances associated with welding, and designated as time-

weighted average threshold limit values (TLV) and ceiling values,

have been established by the American Conference of Governmental

Industrial Hygienists (ACGIH) and Permissable Exposure Limits

(PEL) by the Occupational Safety and Health Administration

(OSHA). Compliance with these acceptable levels can be checked by

sampling the atmosphere under the welder’s helmet or in the imme-

diate vicinity of the helper’s breathing zone. The principle composi-

tion or particulate matter (welding fume) which may be present

within the welder’s breathing zone are listed on the MSDS for the

consumable being used. Sampling should be in accordance with ANSI/

AWS F1.1, Method for Sampling Airborne Particulates Generated by

Welding and Allied Processes.

8ANSI Z49.1 is available from the American Welding Society, 550

N.W. LeJeune Road, Miami, Florida 33126. It may also be down-

loaded at no charge from the www.aws.org website.

9ANSI Z49.2 is available from the American National Standards

Institute, 11 West 42nd Street, New York, NY 10036.

10 CGA P-1 is available from the Compressed Gas Association, Inc.,

1235 Jefferson Davis Highway, Suite 501, Arlington, VA 22202.

SAFE PRACTICES

28

www.lincolnelectric.com

Aluminum

FOR ENGINE

powered equipment.

1.a. Turn the engine off before troubleshooting and maintenance

work unless the maintenance work requires it to be running.

____________________________________________________

1.b.Operate engines in open, well-ventilated

areas or vent the engine exhaust fumes

outdoors.

____________________________________________________

1.c. Do not add the fuel near an open flame

welding arc or when the engine is running.

Stop the engine and allow it to cool before

refueling to prevent spilled fuel from vaporiz-

ing on contact with hot engine parts and

igniting. Do not spill fuel when filling tank. If

fuel is spilled, wipe it up and do not start

engine until fumes have been eliminated.

____________________________________________________

1.d. Keep all equipment safety guards, covers and devices in

position and in good repair.Keep hands, hair, clothing and

tools away from V-belts, gears, fans and all other moving

parts when starting, operating or repairing equipment.

____________________________________________________

1.e. In some cases it may be necessary to remove safety

guards to perform required maintenance. Remove

guards only when necessary and replace them when the

maintenance requiring their removal is complete.

Always use the greatest care when working near moving

parts.

___________________________________________________

1.f. Do not put your hands near the engine fan.

Do not attempt to override the governor or

idler by pushing on the throttle control rods

while the engine is running.

___________________________________________________

1.g. To prevent accidentally starting gasoline engines while

turning the engine or welding generator during maintenance

work, disconnect the spark plug wires, distributor cap or

magneto wire as appropriate.

i

SAFETY

i

ARC WELDING CAN BE HAZARDOUS. PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH.

KEEP CHILDREN AWAY. PACEMAKER WEARERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE OPERATING.

Read and understand the following safety highlights. For additional safety information, it is strongly recommended that you

purchase a copy of “Safety in Welding & Cutting - ANSI Standard Z49.1” from the American Welding Society, P.O. Box

351040, Miami, Florida 33135 or CSA Standard W117.2-1974. A Free copy of “Arc Welding Safety” booklet E205 is available

from the Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, Ohio 44117-1199.

BE SURE THAT ALL INSTALLATION, OPERATION, MAINTENANCE AND REPAIR PROCEDURES ARE

PERFORMED ONLY BY QUALIFIED INDIVIDUALS.

WARNING

Mar ‘95

ELECTRIC AND

MAGNETIC FIELDS

may be dangerous

2.a. Electric current flowing through any conductor causes

localized Electric and Magnetic Fields (EMF). Welding

current creates EMF fields around welding cables and

welding machines

2.b. EMF fields may interfere with some pacemakers, and

welders having a pacemaker should consult their physician

before welding.

2.c. Exposure to EMF fields in welding may have other health

effects which are now not known.

2.d. All welders should use the following procedures in order to

minimize exposure to EMF fields from the welding circuit:

2.d.1.

Route the electrode and work cables together - Secure

them with tape when possible.

2.d.2. Never coil the electrode lead around your body.

2.d.3. Do not place your body between the electrode and

work cables. If the electrode cable is on your right

side, the work cable should also be on your right side.

2.d.4. Connect the work cable to the workpiece as close as

possible to the area being welded.

2.d.5. Do not work next to welding power source.

1.h. To avoid scalding, do not remove the

radiator pressure cap when the engine is

hot.

CALIFORNIA PROPOSITION 65 WARNINGS

Diesel engine exhaust and some of its constituents

are known to the State of California to cause

cancer, birth defects, and other reproductive harm.

The engine exhaust from this product contains

chemicals known to the State of California to cause

cancer, birth defects, or other reproductive harm.

The Above For Diesel Engines The Above For Gasoline Engines

29

Aluminum

www.lincolnelectric.com

ii

SAFETY

ii

ARC RAYS can burn.

4.a. Use a shield with the proper filter and cover

plates to protect your eyes from sparks and

the rays of the arc when welding or observing

open arc welding. Headshield and filter lens

should conform to ANSI Z87. I standards.

4.b. Use suitable clothing made from durable flame-resistant

material to protect your skin and that of your helpers from

the arc rays.

4.c. Protect other nearby personnel with suitable, non-flammable

screening and/or warn them not to watch the arc nor expose

themselves to the arc rays or to hot spatter or metal.

ELECTRIC SHOCK can

kill.

3.a. The electrode and work (or ground) circuits

are electrically “hot” when the welder is on.

Do not touch these “hot” parts with your bare

skin or wet clothing. Wear dry, hole-free

gloves to insulate hands.

3.b. Insulate yourself from work and ground using dry insulation.

Make certain the insulation is large enough to cover your full

area of physical contact with work and ground.

In addition to the normal safety precautions, if welding

must be performed under electrically hazardous

conditions (in damp locations or while wearing wet

clothing; on metal structures such as floors, gratings or

scaffolds; when in cramped positions such as sitting,

kneeling or lying, if there is a high risk of unavoidable or

accidental contact with the workpiece or ground) use

the following equipment:

• Semiautomatic DC Constant Voltage (Wire) Welder.

• DC Manual (Stick) Welder.

• AC Welder with Reduced Voltage Control.

3.c. In semiautomatic or automatic wire welding, the electrode,

electrode reel, welding head, nozzle or semiautomatic

welding gun are also electrically “hot”.

3.d. Always be sure the work cable makes a good electrical

connection with the metal being welded. The connection

should be as close as possible to the area being welded.

3.e. Ground the work or metal to be welded to a good electrical

(earth) ground.

3.f.

Maintain the electrode holder, work clamp, welding cable and

welding machine in good, safe operating condition. Replace

damaged insulation.

3.g. Never dip the electrode in water for cooling.

3.h. Never simultaneously touch electrically “hot” parts of

electrode holders connected to two welders because voltage

between the two can be the total of the open circuit voltage

of both welders.

3.i. When working above floor level, use a safety belt to protect

yourself from a fall should you get a shock.

3.j. Also see Items 6.c. and 8.

FUMES AND GASES

can be dangerous.

5.a. Welding may produce fumes and gases

hazardous to health. Avoid breathing these

fumes and gases.When welding, keep

your head out of the fume. Use enough

ventilation and/or exhaust at the arc to keep

fumes and gases away from the breathing zone. When

welding with electrodes which require special

ventilation such as stainless or hard facing (see

instructions on container or MSDS) or on lead or

cadmium plated steel and other metals or coatings

which produce highly toxic fumes, keep exposure as

low as possible and below Threshold Limit Values (TLV)

using local exhaust or mechanical ventilation. In

confined spaces or in some circumstances, outdoors, a

respirator may be required. Additional precautions are

also required when welding on galvanized steel.

5.b.

Do not weld in locations near chlorinated hydrocarbon

vapors

coming from degreasing, cleaning or spraying operations.

The heat and rays of the arc can react with solvent vapors

to f

orm phosgene, a highly toxic gas, and other irritating

products.

5.c. Shielding gases used for arc welding can displace air and

cause injury or death. Always use enough ventilation,

especially in confined areas, to insure breathing air is safe.

5.d. Read and understand the manufacturer’s instructions for this

equipment and the consumables to be used, including the

material safety data sheet (MSDS) and follow your

employer’s safety practices. MSDS forms are available from

your welding distributor or from the manufacturer.

5.e. Also see item 1.b. Mar ‘95

30

www.lincolnelectric.com

Aluminum

FOR ELECTRICALLY

powered equipment.

8.a. Turn off input power using the disconnect

switch at the fuse box before working on

the equipment.

8.b. Install equipment in accordance with the U.S. National

Electrical Code, all local codes and the manufacturer’s

recommendations.

8.c. Ground the equipment in accordance with the U.S. National

Electrical Code and the manufacturer’s recommendations.

CYLINDER may explode

if damaged.

7.a. Use only compressed gas cylinders

containing the correct shielding gas for the

process used and properly operating

regulators designed for the gas and

pressure used. All hoses, fittings, etc. should be suitable for

the application and maintained in good condition.

7.b. Always keep cylinders in an upright position securely

chained to an undercarriage or fixed support.

7.c. Cylinders should be located:

•Away from areas where they may be struck or subjected to

physical damage.

•A safe distance from arc welding or cutting operations and

any other source of heat, sparks, or flame.

7.d. Never allow the electrode, electrode holder or any other

electrically “hot” parts to touch a cylinder.

7.e. Keep your head and face away from the cylinder valve outlet

when opening the cylinder valve.

7.f. Valve protection caps should always be in place and hand

tight except when the cylinder is in use or connected for

use.

7.g. Read and follow the instructions on compressed gas

cylinders, associated equipment, and CGA publication P-l,

“Precautions for Safe Handling of Compressed Gases in

Cylinders,” available from the Compressed Gas Association

1235 Jefferson Davis Highway, Arlington, VA 22202.

iii

SAFETY

iii

Mar ‘95

WELDING SPARKS can

cause fire or explosion.

6.a.

Remove fire hazards from the welding area.

If this is not possible, cover them to prevent

the welding sparks from starting a fire.

Remember that welding sparks and hot

materials from welding can easily go through small cracks

and openings to adjacent areas. Avoid welding near

hydraulic lines. Have a fire extinguisher readily available.

6.b. Where compressed gases are to be used at the job site,

special precautions should be used to prevent hazardous

situations. Refer to “Safety in Welding and Cutting” (ANSI

Standard Z49.1) and the operating information for the

equipment being used.

6.c. When not welding, make certain no part of the electrode

circuit is touching the work or ground. Accidental contact

can cause overheating and create a fire hazard.

6.d. Do not heat, cut or weld tanks, drums or containers until the

proper steps have been taken to insure that such procedures

will not cause flammable or toxic vapors from substances

inside. They can cause an explosion even

though

they have

been “cleaned”. For information, purchase “Recommended

Safe Practices for the

Preparation

for Welding and Cutting of

Containers and Piping That Have Held Hazardous

Substances”, AWS F4.1 from the American Welding Society

(see address above 1.a. [Safety]).

6.e. Vent hollow castings or containers before heating, cutting or

welding. They may explode.

6.f.

Sparks and spatter are thrown from the welding arc. Wear oil

free protective garments such as leather gloves, heavy shirt,

cuffless trousers, high shoes and a cap over your hair. Wear

ear plugs when welding out-of-position or in confined places.

Always wear safety glasses with side shields when in a

welding area.

6.g. Connect the work cable to the work as close to the welding

area as practical. Work cables connected to the building

framework or other locations away from the welding area

increase the possibility of the welding current passing

through lifting chains, crane cables or other alternate

circuits. This can create fire hazards or overheat lifting

chains or cables until they fail.

6.h. Also see item 1.c.

31

www.lincolnelectric.com

Aluminum

Notes

CUSTOMER ASSISTANCE POLICY

The business of The Lincoln Electric Company is manufacturing and selling high quality welding equipment, consumables, and cutting equipment. Our challenge is to meet the

needs of our customers and to exceed their expectations. On occasion, purchasers may ask Lincoln Electric for advice or information about their use of our products. We respond

to our customers based on the best information in our possession at that time. Lincoln Electric is not in a position to warrant or guarantee such advice, and assumes no liability,

with respect to such information or advice. We expressly disclaim any warranty of any kind, including any warranty of fitness for any customer’s particular purpose, with respect to

such information or advice. As a matter of practical consideration, we also cannot assume any responsibility for updating or correcting any such information or advice once it has

been given, nor does the provision of information or advice create, expand or alter any warranty with respect to the sale of our products.

Lincoln Electric is a responsive manufacturer, but the selection and use of specific products sold by Lincoln Electric is solely within the control of, and remains the sole responsibility

of the customer. Many variables beyond the control of Lincoln Electric affect the results obtained in applying these types of fabrication methods and service requirements.

Subject to Change – This information is accurate to the best of our knowledge at the time of printing. Please refer to www.lincolnelectric.com for any updated information.

Aluminum Welding Guide

C8.100 9/06

LINCOLN NORTH AMERICA

DISTRICT SALES OFFICES

U.S.A.

ALABAMA

BIRMINGHAM 35124-1156

(205) 988-8232

MOBILE 36582-5209

(251) 443-6524

ALASKA

Contact VANCOUVER, WA

(360) 693-4712

ARIZONA

PHOENIX 85260-1745

(480) 348-2004

ARKANSAS

LITTLE ROCK 72032-4371

(501) 764-0480

CALIFORNIA

FRESNO 93722-3949

(559) 276-0110

LOS ANGELES 90670-2936

(562) 906-7700

SAN DIEGO 92065-4165

(760) 787-1970

NORTHERN CALIFORNIA

95762-5706

(916) 939-8788

COLORADO

DENVER 80112-5115

(303) 792-2418

CONNECTICUT

NORTH HAVEN 06238-1090

(860) 742-8887

FLORIDA

JACKSONVILLE 32216-4634

(904) 642-3177

MIAMI 33178-1175

(305) 888-3203

ORLANDO 32714-1974

(407) 788-8557

TAMPA 33594

(813) 477-5817

GEORGIA

ATLANTA 30076-4914

(770) 475-0955

SAVANNAH 31324-5180

(912) 727-4286

HAWAII

Contact LOS ANGELES, CA

(562) 906-7700

IDAHO

BOISE 83616-6646

(208) 938-2302

ILLINOIS

CHICAGO 60527-5629

(630) 920-1500

PEORIA 60527-5629

(630) 920-1500

INDIANA

EVANSVILLE 47630

(812) 454-3428

FT. WAYNE 46825-5547

(260) 484-4422

SOUTH BEND 46561-9160

(219) 674-5523

INDIANAPOLIS 46250-5536

(317) 845-8445

IOWA

CEDAR RAPIDS 52402-3160

(319) 362-6804

DAVENPORT 52806-1344

(563) 386-6522

DES MOINES 50265-6218

(515) 963-1778

KANSAS

KANSAS CITY 66214-1625

(913) 894-0888

WICHITA 67037-9614

(316) 788-7367

KENTUCKY

LOUISVILLE 47112-7025

(502) 727-7335

LOUISIANA

BATON ROUGE 70808-3150

(225) 922-5151

LAFAYETTE 70507-3126

(337) 886-1090

SHREVEPORT 75692-9313

(318) 518-4099

MARYLAND

BALTIMORE 21050-3067

(443) 831-0416

MASSACHUSETTS

BOSTON 01701-7726

(508) 788-9353

MICHIGAN

DETROIT 48034-4005

(248) 353-9680

FLINT 48439-8728

(810) 695-2627

GRAND RAPIDS 49512-3924

(616) 942-8780

MINNESOTA

MINNEAPOLIS 55447-4743

(763) 551-1990

MISSISSIPPI

JACKSON 39212-9635

(601) 372-7679

MISSOURI

KANSAS CITY (KS) 66214-1625

(913) 894-0888

ST. LOUIS 63045

(314) 291-5877

SPRINGFIELD 65804

(417) 841-2779

MONTANA

Contact VANCOUVER, WA

(360) 693-4712

NEBRASKA

OMAHA 68046-2826

(402) 339-1809

NEW JERSEY

EDISON 08837-3939

(732) 225-2000

NEW MEXICO

ALBUQUERQUE 87008

(505) 890-6347

NEW YORK

ALBANY 12304-4320

(518) 469-8222

BUFFALO 14075-2520

(716) 646-8414

NEW YORK CITY

(888) 269-6755

SYRACUSE 13057-9313

(315) 432-0281

NORTH CAROLINA

CHARLOTTE 28273-6200

(704) 588-3251

RALEIGH 27604-8456

(919) 303-1972

OHIO

AKRON 44236-4680

(330) 342-8009

CINCINNATI 45242-3706

(513) 554-4440

CLEVELAND 44117-2525

(216) 383-2662

COLUMBUS 43221-4073

(614) 488-7913

DAYTON 45458

(937) 885-6964

TOLEDO 43528-9483

(419) 867-7284

OKLAHOMA

OKLAHOMA CITY 73139-2432

(405) 616-1751

TULSA 74146-1622

(918) 622-9353

PENNSYLVANIA

PHILADELPHIA 19008-4310

(610) 543-9462

PITTSBURGH 15001-4800

(724) 857-2750

HARRISBURG

17104-1422

(717) 213-9163

SOUTH CAROLINA

GREENVILLE 29681-4724

(864) 967-4157

COLUMBIA 29209

(803) 783-2851

SOUTH DAKOTA

SIOUX FALLS 57108-2609

(605) 339-6522

TENNESSEE

KNOXVILLE 37922-1736

(423) 612-1204

MEMPHIS 38119

(901) 683-6260

NASHVILLE 37228-1708

(615) 291-9926

TRI-CITIES 37659-5693

(423) 612-1204

TEXAS

DALLAS 76051-7602

(817) 329-9353

HOUSTON 77060-3143

(281) 847-9444

SAN ANTONIO 78258-4009

(210) 393-9337

UTAH

MIDVALE 84047-3759

(801) 233-9353

VIRGINIA

LEESBURG, VA 20175-3911

Washington, D.C.

(703) 904-7735

DANVILLE

(434) 489-3222

HAMPTON ROADS 23693-4171

(757) 870-5508

WASHINGTON

VANCOUVER 98661-8023

(360) 693-4712

SPOKANE 99005-9637

(509) 468-2770

WASHINGTON DC

LEESBURG, VA 20175-3911

(703) 904-7735

WEST VIRGINIA

CHARLESTON 25526-8864

(304) 757-9862

WISCONSIN

GREEN BAY 54302-1829

(920) 435-1012

MILWAUKEE 53186-0403

(262) 650-9364

CANADA

ALBERTA

CALGARY

(403) 253-9600/(877) 600-WELD

EDMONTON

(780) 436-7385

WINNIPEG

(204) 488-6398

BRITISH COLUMBIA

VANCOUVER

(604) 945-7524

MARITIMES

NEW BRUNSWICK

(506) 849-4474

MANITOBA

WINNIPEG

(204) 488-6398

ONTARIO

MISSISSAUGA

(905) 565-5600

TORONTO

(416) 421-2600/(800) 268-0812

QUEBEC

MONTREAL

(450) 654-3121

LINCOLN INTERNATIONAL HEADQUARTERS

HARRIS CALORIFIC DIVISION

2345 Murphy Blvd., Gainesville, Georgia 30504 U.S.A.

Phone: 1-800-241-0804 • Fax: (770) 535-0544 • Web Site: www.harriscal.com

LATIN AMERICA

Miami, Florida U.S.A.

Phone: (305) 888-3203

EUROPE

Barcelona, Spain

Phone: 34 91 816 4266

RUSSIA, AFRICA & MIDDLE EAST

Cleveland, Ohio U.S.A.

Phone: (216) 481-8100

ASIA PACIFIC

Singapore

Phone: 65 6773 6689

Australia

Phone: 61 2 9772 7222