Ovako Bearing Steel.07 803D Steels For Bearings From

User Manual: 803D

Open the PDF directly: View PDF .
Page Count: 16

Steels for bearing

production from Ovako

–2–

Contents:

Metallurgy of bearing steels

Steel grades

Research and developemnt

For bars, tubes, rings and wire rod,

see brochures:

Bar products from Ovako, also available in German, French,

Polish, Finnish and Swedish

Seamless Tubes from Ovako, also available in German, French,

Finnish and Swedish

Rolled and forged rings from Ovako

Wire rod for a broad scope of applications, also available in

German, French and Polish

These brochures can be ordered or printed as PDF from our website.

vako is one of the world’s largest manufacturers

of through-hardening bearing steel. We will maintain this

leading position as the bearing industry continuously

challenges us to make further technical and logistical im-

provements. As a supplier to most of the leading bearing

producers, we have acquired unique knowledge and ex-

perience in this field.

Total Control

Ovako is a fully integrated bearing steel producer.

We control the whole chain of production, from

melting the steel through rolling to producing a

finished component.

Our product range of tube, bar, ring and wire

accommodates all the main components of a rolling

bearing. And we meet all the requirements specified

irrespective of the type of steel used for rolling

bearing manufacture.

Total Partnership

Our objective is to be a true partner with our customers,

from both a technical and business point of view.

Our technical specialists are dedicated to working

closely with those of our customers. This allows us to

optimise the use of steel both from a product and a

production perspective. We can develop new and better

steels, tailor-make products and improve machinability

and heat treatment responses.

By co-operating with our key customers we are able

to establish long-term business agreements and customise

logistical and EDI solutions. We support them in their

global sourcing strategies and contribute with multiple

product packages that keep administration to a minimum.

We also have experience in joint cost- reduction activities.

Total Quality

Total Quality Management is a central concept within

Ovako. All our activities aim at producing and delivering

products and services to fulfil customer’s needs. Our

quality policy and comprehensive quality assurance help

us to achieve the highest standards.

Ovako’s quality system conforms to ISO/TS 16949 and

ISO 9001. The company is also ISO 14001 certified.

–3–

The demand for increased reliability of rolling bearings in

service is continuous. Bearings are expected to last longer

and endure higher stress under adverse conditions. This

poses higher demands on the steel used by bearing

manufacturers.

Our long-standing cooperation with the world’s leading

rolling bearing manufacturers has given Ovako a unique

understanding of material development for rolling bearing

applications.

By optimising and making full use of these skills in

each production step we can achieve high quality bearing

steel with optimum mechanical properties. Each step must

be controlled with a high degree of precision to minimise

the content of harmful non-metallic inclusions.

By controlling cleanliness carefully and through the

use of a number of key technologies,

such as magnetic induction stirring and

vacuum degassing in the the secondary

metallurgy, and controlled casting,

it has been possible to increase the

fatigue strength of our bearing

steels considerably.

The objective is to produce steel,

which is optimised regarding properties,

quality and economy.

Metallurgy of bearing steels

–4–

Clockwise from top left:

Steel melting, continuous casting,

billet rolling and oxygen scarfing.

Steel making and billet production

Ovako has four steel works, three of which have a scrap melting electric arc process

and one blast furnace – oxygen converter process. Like most other producers of

bearing steel, Ovako uses scrap melting process as its basis for bearing steel

production. The blast furnace – oxygen converter process is also a possibility to

make bearing steels.

Raw material

Like most other producers of bearing steel, Ovako uses scrap as its basic raw material.

The selection and procurement of scrap is of great importance to the quality of the

end product. For that reason we have high demands and tight control over the scrap

we use. Used ferroalloys and other additions, too, are carefully controlled.

Melting

The melting process requires complete control of all parameters, from liquid raw melt

to furnace control, so that the melt has the correct properties when it goes to the

next stage of production. At this stage, a number of the most important properties

inherent in the cast are already fixed.

Secondary metallurgy

This process stage determines the final metallurgical quality, i.e. the final chemical

composition and the cleanliness of the steel.

The metallurgical unit operations in this part of the production process include:

• control of alloy content

• deoxidation (reducing the oxygen content and inclusion count in the steel)

• desulphurisation (reducing the sulphur content of the steel)

• degassing (elimination of other harmful gases)

• temperature adjustment (to reach the appropriate temperature for teeming).

• soft induction stirring

During this secondary metallurgy treatment the molten steel is stirred by an induction

coil or by argon bubbling to create the best possible uniformity, removing oxide

inclusions, sulphur and undesirable gases.

Casting

There are two ways to solidify bearing steels in Ovako: the traditional ingot casting

and continuous bloom casting.

The uphill teeming of ingots is Ovako’s traditional casting technique. It creates

large forging reductions, so as to achieve the desired final quality requirements. For

some bearing steel products it is the only accessible casting method. Uphill teeming

ensures a minimum of inclusions and a good surface finish. The design of the ingot

mould has been optimised to reduce segregation in the steel during solidification,

and during teeming the molten steel is shrouded by inert gas to protect it from

reacting with the air around it.

Once solidified, the ingots are stripped from the moulds and taken directly to

the soaking pits and brought to an adequate temperature before primary rolling.

The soaking is introduced to avoid harmful segregation in the steel.

Ovako has also a very long experience in continuous casting. The first concast

facility was started up in 1965 at Imatra Steel Works. The bloom caster, which was

modernised recently, represents the latest concast technology. The large bloom size

of 370×310 mm results in a good deformation in rolling. Naturally all molten surfaces

are protected and the mould stirring is standard Ovako practice.

The solidified blooms are hot charged into the reheating furnace for rolling. This

beneficial process provides clear advantages in surface quality and low level of

segregations, resulting in good production economy.

Billet rolling

The entire metallurgical process at Ovako, from the steel melting to the finished billet,

is carried out in a hot flow in order to minimise the risk of surface defects. Billets can

be surface conditioned by oxygen scarfing after the first stages of primary rolling, or

by grinding.

Before the billets are transferred for secondary rolling, i.e. tube, bar, wire or rings,

they are subject to magnetic particle testing testing, and, if needed, to grinding to

remove the possible surface defects.

–5–

Scrapping

Melting

Secondary

metallurgy

Rolling

Continuous

casting

Magnetic particle

testing

Ingot

casting

Ovako mainly produces through-hardening steels for

bearing applications, and is one of the world’s leading

companies in this segment. We also produce a significant

quantity of carburising steel grades for this application.

Listed below are some of our standard grades for bearing

applications.

Through-hardening

bearing steels

Ovako specialises in high-strength through-hardening

bearing steels. These grades exhibit high fatigue and wear-

resistance, good machinability, high hardness and good

dimensional stability. A hardness of 60-65 HRC can be

achieved through martensitic hardening and tempering,

making these steels ideal for bearing products. This

distinguishing property package is also suitable for other

market segments and applications that have the same high

quality requirements as the bearing industry.

100Cr6 type (SAE 52100)

Used mainly for small and medium-sized bearing compo-

nents. The 100Cr6 steel grades have high fatigue strength

and hardness, and good wear resistance. There are several

different versions of this grade. For example:

Air hardening type

A steel grade specifically designed for air or gas quenching.

By using gas cooling or air hardening it is possible to re-

duce the amount of quench distortion. The use of quenching

mediums such as oil and salt can also be avoided.

Hardenability corresponds to a bar with approx. Ø 40 mm

(cooled in still air). The Ovatec®677 series demonstrate

very good mechanical performance, and is often

recommended for the most demanding applications.

Steel grades

–6–

Designation acc. Ovako

to EN 10027-1 designation

100Cr6 803J Standard.

100Cr6 mod. F 803F With a controlled sulphur concontent for consistent machining properties.

100Cr mod. Q 803Q Isotropic properties and better fatigue strength due to higher cleanliness

levels, and a finer size and distribution of non-metallic inclusions.

100Cr6 mod. Z 803Z Better cold forming properties due to reduction of the silicon content.

100Cr6 mod. D 803D Better machinability due to the higher sulphur content.

Designation acc. Ovako

to EN 10027-1 designation

70SiCrMnMo6-5 Ovatec®677L Standard.

65SiCrMnMo6-5 Ovatec®677Q Isotropic properties and better fatigue strength due to higher

cleanliness and a finer size and distribution of non-metallic

inclusions.

Through-hardening bearing steels

for bainitic hardening

These grades are used for bainitic hardened medium and

large-sized bearing components. They all have a high

fatigue strength, good toughness and excellent wear re-

sistance. The through-hardenability corresponds to a ring

with wall thickness T, quenched in oil.

Through-hardening bearing steels

for martensite hardening

These grades are used for the martensite hardening of

large- and medium-sized bearing components. They have

high fatigue strength, high hardness and good wear

resistance. The through hardenability corresponds to

a ring with wall thickness T, quenched in oil.

Case-hardening bearing steels

Ovako’s case-hardening bearing steels are adjusted to offer

good machinability and minimal dimensional change after

hardening. The hard surface generated from case-

hardening provides high fatigue strength and high wear-

resistance, while the softer core gives the component

a high toughness. Ovako produces a number of case-

hardening steels suitable for bearing applications.

For example:

Definition of ring

wall thickness

The ‘‘T’’ section is

defined as the material

thickness that is the

controlling factor in

the heat treatment

process, sometimes

called the ruling

section.

T

–7–

Designation acc. Ovako

to EN 10027-1 designation

100CrMo7 824B Through hardenability corresponds to T< 20 mm (~ Ø 35 mm bar)

100CrMo7-3 825B Through hardenability corresponds to T< 30 mm (~ Ø 50 mm bar)

100CrMo7-4 826B Through hardenability corresponds to T< 50 mm (~ Ø 80 mm bar)

Designation acc. Ovako

to EN 10027-1 designation

100CrMnSi4-4 831B Through hardenability corresponds to T< 20 mm (~ Ø 35 mm bar)

100CrMnSi6-4 837B Through hardenability corresponds to T< 30 mm (~ Ø 50 mm bar)

Designation acc. Ovako

to EN 10027-1 designation

20MnCr6-3 126H Standard carburising steel with good toughness and high

fatigue strength.

20NiCrMo2-2 152G Increased toughness due to a higher nickel content. Also available

with normal sulphur content for better machinability.

17MnCr5 234K Controlled hardenability due to a tighter chemical composition.

18CrNiMo14-6 255G Excellent toughness and high fatigue strength, due to a higher

cleanliness specification and a high nickel content.

18CrMnMoNi9-5-5 277L Air-hardening carburising steel with high toughness and high

fatigue strength.

18CrMnMoNi9-5-5 mod. 277Q Same as above, but higher cleanliness level.

Steel designation according to Quality C Si Mn S max. Cr Ni Mo

EN 10027-1 Ovako level %% % % %% %

100Cr6 803J BQ 0.97 0.25 0.35 0.015 1.50 --

100Cr6 mod. F 803F BQ 0.97 0.27 0.35 0.015 1.50 --

100Cr mod. Q 803Q IQ 0.95 0.30 0.30 0.002 1.50 --

100Cr mod. Z 803Z BQ 0.97 < 0.15 0.35 0.015 1.45 --

100Cr mid. D 803D BQ 1.02 0.30 0.35 0.025 1.50 --

70SiCrMnMo6-5 677L BQ 0.70 1.55 1.40 0.015 1.10 - 0.25

65SiCrMnMo6-5 mod. Q 677Q IQ 0.65 1.50 1.40 0.002 1.10 - 0.25

100CrMo7 824B BQ 0.97 0.30 0.30 0.015 1.80 - 0.20

100CrMo7-3 825B BQ 0.97 0.30 0.70 0.015 1.80 - 0.30

100CrMo7-4 826B BQ 0.97 0.35 0.70 0.015 1.80 - 0.45

100CrMnMoSi8-4-6 827B BQ 0.97 0.50 0.90 0.015 1.90 - 0.55

100CrMnSi4-4 831B BQ 0.97 0.60 1.10 0.015 1.00 --

100CrMnSi6-4 837B BQ 1.00 0.60 1.10 0.015 1.50 --

26MnCr6-326 126H BQ 0.20 0.27 0.80 0.025 0.50 --

20NiCrMo2-2 152G BQ 0.21 0.25 0.75 0.015 0.50 0.55 -

17MnCr5 234K BQ 0.16 0.25 1.15 0.035 0.95 --

18CrNiMo14-6 255G PBQ 0.16 0.27 0.55 0.005 1.45 3.50 0.20

18CrMnMoNi9-5-5 277L BQ 0.18 0.35 1.30 0.030 2.20 0.50 0.50

18CrMnMoNi9-5-5 mod. Q 277Q PBQ 0.18 0.35 1.30 0.030 2.20 0.50 0.50

EN ISO 683-17 Ovako ASTM AFNOR DIN BS SAE SS

NF A35-565:1970 17230:1980

100Cr6 803J A732 100 C 6 100 Cr 6 2 S.135 52100 2258

100Cr6 803F A732 100 C 6 100 Cr 6 2 S.135 52100 2258

100Cr6 803Q A732 100 C 6 100 Cr 6 2 S.135 52100 2258

803Z

100Cr6 803D A732 100 C 6 100 Cr 6 2 S.135 52100 2258

677L

677Q

100CrMo7 824B 100 CD 7 100 CrMo 7

100CrMo7-3 825B 100 CrMo 7-3

100CrMo7-4 826B

100CrMnMoSi8-4-6 827B 100 CrMnMo 8

100CrMnSi4-4 831B A485

100CrMnSi6-4 837B 100 CM 6 100 CrMn 6

126H A534

20NiCrMo2 152G A322 20 NCD 2 805 A 20 2506

17MnCr5 234K 16 MC 5 16 MnCr 5 590 A 17

18NiCrMo14-6 255G A757 17 NiCrMo 14

277L

Average chemical composition

Comparable standards

–8–

Steel designation according to Structure Hardness Rm(MPa) ReH (MPa) A5(%) Z (%)

EN 10027-1 Ovako

100Cr6 803 Martensite 61- 64 HRC 2300 1 700 22

Bainite 58- 61 HRC 2300 2 100 57

70SiCrMnMo6-5 677L Martensite 61- 64 HRC 2300 1700 22

65SiCrMnMo6-5 mod. Q 677Q Martensite 61- 64 HRC 2300 1700 22

100CrMo7 824B Bainite 58- 61 HRC 2300 2100 57

100CrMo7-3 825B Bainite 58- 61 HRC 2300 2100 57

100CrMo7-4 826B Bainite 58- 61 HTC 2300 2100 57

100CrMnMoSi8-4-6 827B Bainite 58- 61 HRC 2300 2100 55

100CrMnSi4-4 831B Martensite 61- 64 HRC 2300 1700 22

100CrMnSi6-4 837B Martensite 61- 64 HRC 2300 1700 22

26MnCr6-3 126H Case hardened 300-430 HB 980-1 370 800-900 10-12

20NiCrMo2-2 152G Case hardened 300-430 HB 980-1370 800-900 10-12

17MnCr5 234K Case hardened 250-350 HB 880-1180 640 9

18CrMnMoNi9-5-5 277L Case hardened 350-370 HB 1100-1300 850-950 10-12

Typical mechanical properties

The properties correspond to typical values of core after hardening or

case-hardening.

–9–

– 10 –

Cleanliness specifications

Ovako’s continuous development of its steel making prac-

tice over the last decade has made it possible to further

control the oxygen and sulphur content in our products.

The maximum inclusion levels have been significantly

lowered, thereby ensuring steels with consistently high

cleanliness and superior fatigue properties.

In addition to bearing quality level (BQ) Ovako has three

more quality categories for bearing steels.

CQ The Customer Quality level. Limits are defined

according to specific customer requests and

agreed mutually.

PBQ The Premium Bearing Quality is intended for

more demanding applications that require extra

clean steel grades.

IQ The Isotropic Quality for applications requiring

exceptional fatigue properties, and cleanliness

levels comparable to Electro Slag Re-melt (ESR)

and Vacuum Arc Re-melt (VAR) steels.

A-type inclusion. D-type inclusion.B-type inclusion. Titanium inclusion.

Typical microscopic inclusions

Fatigue testing equipment.

– 11 –

The art of making steel requires an understanding of steel

and an ability to predict what will happen to the steel in

various situations.

It is essential for Ovako as a supplier to the rolling

bearing industry that we increase our knowledge and

understanding about the steel and the products made from

it, thereby improving and meeting the increasing market

demands and expectations. It is our explicit policy to

continue to strengthen our position within this market

segment, so it is not by chance that we are the company

that has developed and applied for more patents for bearing

steels and heat treatment variants than any other company

in the Western world. Ovako has developed and introduced

many new steel grades.

Neither is it by chance that we were the first in the

world to actively control the hardenability of the steel

during the production. We were also the first to achieve

inclusion levels in conventionally produced steels

comparable with those of re-melted steels.

Today, our research and development activities are

concentrating on a greater understanding of steel and

how it performs from a metallurgical point of view and

how that affects the material properties. Our ultimate

target is to optimise the steel performance for every

application and to come up with entirely new, cost

effective material solutions. We are active in developing

and improving our products. For instance, we are

improving tolerances on diameters, surface roughness,

machinability and heat treatment properties.

Ovako co-operates closely with a number of research

institutes and universities to widen our competence and

knowledge base so as to ensure success in our

development projects.

Research and development

– 12 –

Material development

Ovako continuously strives to obtain a better knowledge

and understanding of the behaviour of our bearing steel

materials through scientific research.

Fatigue testing

Fatigue testing is a useful tool for understanding and deter-

mining the service life of bearing steels. At Ovako we have

test rigs for rolling contact, rotational bending and axial

loading, which all generate valuable information about the

properties of fatigue. A steel grade’s fatigue property is

determined by fatigue life testing in combination with

a measurement of inclusion size and count.

SEM analysis

Ovako uses several ultra-modern Scanning Electron Micro-

scope (SEM) for investigating microstructure, inclusion

characteristics and crack properties. A Field Emission Gun

(FEG) makes it possible to generate quality pictures at very

high resolutions. Analysing systems that uses back scatter

mapping in combination with X-ray spectroscopy are the

most useful tool available for inclusion counting, providing

information about inclusion composition and the size

distribution. One microscope is also equipped with an

Electron Back Scatter Diffraction (EBSD) detector, which

provides information about the crystallographic orientation

and material grain structure.

An Al2O3inclusion. A study inside the inclusion.

A study of fatigued fracture surface in a bearing steel.

The SEM-microscopes are continuously used for many

kinds of investigations.

– 13 –

Ultrasonic testing

Immersion ultrasonic testing is used as routine method of

quality control in many cases. The typical frequency range

when investigating bars and billets is 10 to 25 MHz.

Immersion ultrasonic scanning of samples makes it

possible to see how different manufacturing stages affect

the occurrence of macro inclusions. This means that the

product integrity is improved and changes in the

production process can be followed.

Ovako has gone further, improving and developing

immersion ultrasonic testing methods by the use of

focused, high frequency probes 25 to 80 MHz. This gives

Ovako the possibility to map both macro and meso

inclusions in our steel. Our ultrasonic test equipment gives

us a quick and reliable testing tool for continuous research

and development.

Inclusion distribution diagram. Results from 80 MHz.A test piece scanned with a high-frequency (80 MHz) probe.

A few larger inclusions can be seen in the C-scan image.

The results of the evaluation are presented in a histrogram

(left).

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

22 24 26 28 30 32 34

Size, d (µm)

No./mm2

High frequency ultrasonic scanning of a billet sample.

– 14 –

Ovako is a leading European producer of long

special steel products for the automotive, heavy

vehicle and engineering industries. Production

consists of low alloy and carbon steels in the form

of bars, wire rod, tubes, rings and pre-components.

The company has 16 production sites and several

sales companies in Europe and the USA.

Total steel production is 2 million tonnes.

CO-12GB 08.03 1000 ©Copyright Ovako 2008

SALES UNITS:

Finland:

Ovako Bar Oy Ab

Teollisuuskuja 1

FI-142 00 Turenki

Tel: +358 (0)3 570 26 00

Fax: +358 (0)3 570 26 02

France:

Ovako France S.A.S.

14, rue de Mirande

FR-21000 Dijon

Tel: +33 (0)3 80 54 15 15

Fax: + 33 (0)3 80 50 14 67

Germany/Austria:

Ovako GmbH

Postfach 1255

40672 Erkrath

Tel: +49 (0)211-2504-0

Fax: +49 (0)211-2504-244

Netherlands:

Ovako Bar BeNeLux

Bedrijvenpark Twente 295

NL-7602 KK Almelo

Tel: +31 (0)546-588 360

Fax: +31 (0)546-588 366

Ovako Wire b.v.

Postbus 3

NL-2950 AA Alblasserdam

Tel: +31 (0)78 692 3100

Fax: +31 (0)78 692 3192

Poland:

Ovako Polska Sp. z.o.o.

ILMET Building

15 Jana Pawla II Avenue

PL-00-828 Warsaw

Tel: +48 (0)22 6976464 / 65 / 66

Fax: +48 (0) 22 6976467

Russia:

OOO Ovako

Office 1812

Savelkinskiy proezd, d.4

124482 Zelenograd

Moscow

Tel: +7 (4)95 228 07 80

Fax: +7 (4)95 228 07 81

United Kingdom:

Ovako Ltd.

Unit 2, Britannia Park

Trident Drive

Wednesbury WS10 7XA

Tel: 0121 502 1010

Fax: 0121 505 0019

USA:

Ovako North America, Inc.

1096 Assembly Drive

Suite 312

Fort Mill, SC 29708

Tel: +1-803 1802 1500

Fax: +1-803-1802-1501

PRODUCITON:

Sweden:

Hofors Steelworks:

Ovako Steel AB

SE-813 82 Hofors

Tel: +46 (0)290 250 00

Fax: +46 (0)290 250 25

Hällefors Rolling Mil:

Ovako Steel AB

SE-712 80 Hällefors

Sweden

Tel: +46 (0)591 600 00

Fax: +46 (0)591 606 06

Finland:

Imatra Steel Works:

Ovako Bar Oy Ab

Terästehtaantie 1

FI-55100 Imatra

Tel: +358 (0)5 680 21

Fax: +358 (0)5 680 22 11

Netherlands:

Ovako Wire b.v.

Postbus 3

NL-2950 AA Alblasserdam

Tel: +31 (0)78 692 3100

Fax: +31 (0)78 692 3192

www.ovako.com