Steeltec ETG® 88/100

2

3

Steel for more competitiveness

Steel has been one of the most impor tant

materials going back centuries. We

man ufacture it in the grade and quality

that allow our customers to succeed in

the increasingly tough competitive environ-

ment. Steel from Steeltec is employed

where precision components need to ful fil

the highest requirements, in the millions,

safely and reliably over the years. Com-

ponents that have to be produced effi-

ciently and at low cost. The requirements

placed on steel have changed. What

hasn’t is our passion to continually opti-

mise the way we fulfil them: yester day,

today and in the future.

Comparison of component costs ETG®/hardening steels

10

8

6

4

2

0 Material Turning Drilling Tools Heat treatment

4

ETG®: High-Strength Special Steels

for new challenges

Stronger competitors, declining prices,

shorter deadlines and higher demands re-

garding the quality and safety of the

components to be manufactured: these

are the challenges of the market. Those

who aim to meet these demands and

make a profit turn to new variations of

steel. Steels that enable producers to

reshape and restructure their manufactur-

ing processes and techniques. And thus

make them safer and more cost-effective.

These are steels that

– feature a high strength as drawn,

– possess a high fatigue strength and

abrasion resistance,

– have outstanding machining properties

and are distinguished by short chipping

length during machining,

– exhibit a high degree of uniformity from

heat to heat,

– have low residual stresses and maintain

dimensional stability even with asym-

metrical machining

– guarantee consistent mechanical prop-

erties over the entire cross section and

dimension range.

The unique properties of ETG® 88 and

ETG® 100 High-Strength Special Steels

revolutionise operational processes and

manufacture of components.

ETG® steels open up undreamt-of

possibilities in shaping and structuring

the manufacturing processes:

– elimination of extra operations such

as hardening, straightening, grinding

and deburring

– shorter processing times through faster

machining

– longer tool life

– less machine downtime

– multi-machine operation

– possibility of running unmanned shifts

The added costs of using a higher-

quality material are more than made

up for with the savings in the manu-

facturing process.

For the production of demanding com-

ponents, manufacturers can strengthen

their competitiveness through the use

of High-Strength Special Steels:

– smaller sizes save on weight

– shorter process times

– fewer rejects and improved quality

– high processability

– motivated machine operators

– fewer interfaces and less administration

– satisfied customers

In short: Those who replace stan dard

steels with ETG® High-Strength

Special Steels save on costs, improve

their quality and gain added safety.

ETG®

Hardening steels Total ETG®

Total hardening steels

66

ETG® steels: A unique combination

of properties

The properties of ETG® steels are the out-

come of a combination of know-how

and production possibilities. These include:

– State-of-the-art plants that make it

possible to link different manufacturing

processes together to form a single

production system. Melting, shaping and

manufacturing of components can be

controlled as a whole.

– Effective knowledge management al-

lowing data, experiences and acquired

know-how to be utilised where they

are needed: with the customer, in the

distribution organisations, in the factory.

Everywhere and at all times.

– Efficient IT solutions through which

processes can be analysed, improved

and directed. The stringent checks

during production guarantee consistently

high quality within very close tolerances.

– State-of-the-art testing procedures at all

stages of processing, such as 100%

surface crack testing of all ETG® steels.

– Motivated employees, taking respon-

sibility in their thoughts and actions.

– A network of external partners. In asso-

ciation with customers and suppliers,

universities and research institutes, we

put the emphasis on continually pushing

the existing boundaries.

7

Short chipping length makes for safe production processes

Product range ETG® steels are available in various categories, finishes and sizes:

Steel category Processes Size range mm ToleranceETG® 88 round drawn ≥ 5.0 – ≤ 20.5 h9 > 20.5 – ≤ 64.0 h11 > 64.0 – ≤ 114.3 h12 ground ≥ 5.0 – ≤ 100.0 ≥ IT6ETG® 100 round drawn ≥ 6.0 – ≤ 64.0 h11 > 64.0 – ≤ 70.8 h12 ground ≥ 6.0 – ≤ 70.8 ≥ IT6ETG® 88 hexagonal drawn SW 13 – 27 h11

– Bar lengths: 3 – 6.5 m– Colour coding: ETG® 88 white end face,

ETG® 100 gold end face – Bright-turned and bright-turned/ground

to special order – Other categories to meet special requirements

(e.g. mechanical properties) are available to special order.

– Regular sizes are available from stock.

1010

Uniform mechanical properties over the entire cross section and dimension range

Proof stress related to diameter Hardness at different points of cross section

Diameter [mm]

10

Material properties and fabrication

information

Complex components and demanding

manufacturing processes require the right

material. The more complex the compo-

n ents and the more sophisticated the

manufacturing process, the more impor-

t ant it is to use the right material. The job

of our technical support staff is to sup-

port customers in choosing the materials.

Information of a more general nature

regarding the use of our ETG® steels:

– As with all drawn steels, loads should

be applied longitudinally wherever pos-

sible. With lateral loading, the tensile

strength and proof stress are reduced.

Wall thicknesses of less than 1 mm are

in the critical boundary range.

– In view of the notch sensitivity, sharp-

edged changes in cross-section should

be avoided, especially if sudden

stresses may occur. Particular care

should be taken when using this mate-

rial at temperatures below 0 °C.

– For bolts, screws and gear wheels,

the applicable standards should be con-

sulted.

– ETG® is suitable for threaded bolts with

clamping nuts. It is not suitable though

for screws with heads under stress

except in the case of special fabrication

solutions. ETG® 88 and ETG® 100

do not meet the strength required for

classes 8.8 and 10.9 according to

DIN EN ISO 898-1.

ETG®

ETG® 100ETG® 88

Conventional steel

Rp

0,2

[N

/mm

2]

Conventional steel

>

>> >

>

>

1111

Chemical composition ETG® 88/100, analysis by mass in %:

Element C Si Mn P Smin. 0.42 0.10 1.35 0.24max. 0.48 0.30 1.65 0.04 0.33

The analysis corresponds to SAE1144 and 44SMn28 (1.0762). Piece analysis and melt analysis may vary according to EN 10087, table 2.

Mechanical properties (typical values)

ETG® 88 ETG® 100

Static Dimensions Ø mm 5.0 – 114.3 6.0 – 70.8Proof stress drawn Rp0,2 N/mm2 ≥ 685 ≥ 865 ground Rp0,2 N/mm2 ≥ 685 ≥ 800Tensile strength Rm N/mm2 800 – 950 960 – 1,100Ultimate elongation A5 % ≥ 7 ≥ 6Reduction of area Z % ap. 30 ap. 20Elastic modulus N/mm2 ap. 200,000 ap. 200,000Tensile strength (transverse) Rm N/mm2 ap. 600 ap. 720Hardness HRC ap. 28 ap. 32HB 30 ap. 280 ap. 320Lateral shear strength τs N/mm2 ap. 510 ap. 590Torsional shear strength τt N/mm2 ap. 440 ap. 540Notched impact energy AvRT J ap. 25 ap. 10

Dynamic Tension/compression σw N/mm2 ap. 345 ap. 390Pulsating σsch N/mm2 ap. 490 ap. 540Reverse bending σbw N/mm2 ap. 390 ap. 440Torsional reversal τtw N/mm2 ap. 195 ap. 225Torsional pulsating τsch N/mm2 ap. 345 ap. 390

Fatigue strength values for gear wheels

ETG® 88 ETG® 100

Tooth root stress for pulsating load as drawn σFLim N/mm2 248 272nitrocarburised σFLim N/mm2 301 327

Tooth root stress for alternating load as drawn σWLim N/mm2 174 190nitrocarburised σWLim N/mm2 211 229

Straigth teethed gears (m = 2 mm, z= 17)Tooth system quality 7 acc. to DIN 3961...67Standard values acc. to DIN 3990 resp. ISO 6336

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ETG® and standard steels:

A comparison of the mechanical

properties

ETG® steels can be used instead of a

whole range of standard steels. This cuts

down on logistics expenditures, reduces

the risk of material confusion and lowers

complexity costs. At the same time,

individual components can be made in

smaller size: they become lighter and

less expensive.

ETG® opens up new possibilities

in the manufacture of components:

– Greater safety

– Higher quality

– Lower costs

The use of ETG® helps to optimise

production processes:

– Shorter process cycles

– Elimination of some individual

operations

– Weight savings

Considerable cost savings throughoutthe entire process chain

Steeltec

We bring energy to steel

>

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+C Cold-drawn+C+QT Cold-drawn and tempered +QT+C Tempered and cold-drawn

The guaranteed proof stress for all sizes

means that ETG® can be used for a very

wide range of applications. ETG® can

be used instead of a whole range of stan-

d ard steels. The deciding factor is what

it will be used for. Optimised sizes enable

significant savings in weight and cost.

Strength values of standard steels compared to ETG®

Guaranteed proof stress Rp0.2 [N/mm2] according to EN 10277

Steel category Size range mm Material number EN reference Process 5 – 10 10 – 16 16 – 40 40 – 63 63 – 100

Free-cutting tempering steels1.0726 35S20 +C 480 400 315 285 2551.0756 35SPb20 +C+QT 380 320 320 +QT+C 600 580 550 530 5301.0760 38SMn28 +C 600 530 460 425 3501.0761 38SMnPb28 +C+QT 420 400 380 +QT+C 700 680 650 650 5001.0762 44SMn28 +C 550 500 420 400 3901.0763 44SMnPb28 +C+QT 420 410 400 +QT+C 710 710 660 660 6601.0727 46S20 +C 570 470 375 325 3051.0757 46SPb20 +C+QT 430 370 370 +QT+C 680 650 620 620 6201.0728 60S20 +C 645 540 430 355 3351.0758 60SPb20 +C+QT 570 570 490 450 450

Hardening steels 1.0501/1.0502 C35/C35Pb +C 510 420 320 300 2701.1181 C35E +C+QT 370 320 3201.1180 C35R +QT+C 650 600 530 430 3601.0503/1.1195 C45/C45Pb +C 565 500 410 360 3101.1191 C45E +C+QT 430 370 3701.1201 C45R +QT+C 700 650 570 470 3801.0540 C50 +C 590 520 440 390 1.1206 C50E +C+QT 460 400 4001.1241 C50R +QT+C 720 670 600 540 4701.0601/1.0602 C60/C60Pb +C 630 550 480 1.1221 C60E +C+QT 520 450 4501.1223 C60R +QT+C 750 720 640 560 4801.7033 34Cr4 +C+QT 590 460 4601.7037 34CrS4 +QT+C 800 800 690 560 4801.7035 41Cr4 +C+QT 660 560 5601.7039 41CrS4 +QT+C 900 850 770 640 5801.7218 25CrMo4 +C+QT 600 450 4501.7213 25CrMoS4 +QT+C 800 770 670 520 4501.7225 42CrMo4 +C+QT 750 650 6501.7227 42CrMoS4 +QT+C 920 900 830 730 6501.6582 34CrNiMo6 +C+QT 900 800 800 +QT+C 950 950 950 850 820

High-Strength Special Steels

ETG® 88 drawn 685 ETG® 100 drawn 865

14

Longitudinal strength in relation to stress-relieving temperature Typical values, stress-relieving time approx. 2 h

1,200

1,100

1,000

900

800

700

600

500

16

14

12

10

8

6

4

0 100 200 300 400 500 600

Stress-relieving temperature [°C]

Elo

ngat

ion

A5

[%]

Te

nsile

str

engt

h R

m

Pro

of s

tres

s R

p0,

2 [N

/mm

2]

Rm ETG® 100

Rp ETG® 100

Rm ETG® 88

Rp ETG® 88

ETG® 88

ETG® 100

1,100

1,000

900

800

700

600

500

400

0 100 200 300 400 500 600

Testing temperature [°C]

Tens

ile s

tren

gth

Rm

P

roof

str

ess

Rp0

,2 [N

/mm

2]

Rm

Rp0,2

Changes of the mechanical properties

in relation to temperature

High-temperature longitudinal strength for ETG® 100 in relation to hardening temperature Typical values

15

In contrast with cold-drawn steel bars,

ETG® 100 has low internal stress. How-

ever, this stress can cause distortion in

situations such as:

– asymmetrical machining

– long, narrow components

– thin-walled components

We recommend stress-relieving the ma-

terial for workpieces of this nature.

The stress-relieving temperature should

be at least 300 °C.

Stress-relieving is not usually necessary

with ETG® 88, as its internal stress levels

are so low.

For high-precision threaded spindles

(i.e. lead screws), ETG® 100 should only

be used in stress-relieved form

(approx. 580 – 600 °C, min. 2 h).

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Processing information

The special manufacturing processes

used for ETG® steels result in a unique

combination of high strength combined

with outstanding machining properties.

Orientation values for various machining processes

Machining guidelines Vc [m/min] and f [mm/rev]

ETG® 88 ETG® 100Multi-spindle – CNC turning Vc roughing 240 – 280 210 – 250(Carbide tooling, coated) f 0.20 – 0.60 0.20 – 0.60 Vc finishing 250 – 290 220 – 260 f 0.20 – 0.60 0.20 – 0.60 Vc plunging/parting-off 160 – 240 140 – 220 f 0.15 – 0.50 0.15 – 0.50Multi-spindle – CAM turning Vc roughing 180 – 220 170 – 210(carbide tooling, coated) f 0.05 – 0.20 0.05 – 0.20 Vc finishing 190 – 230 180 – 220 f 0.05 – 0.20 0.05 – 0.20 Vc plunging/parting-off 120 – 180 110 – 170 f 0.10 – 0.40 0.10 – 0.40Short-bed turning – CNC Vc roughing 240 – 280 210 – 250(Carbide tooling, coated) f 0.20 – 0.60 0.20 – 0.60 Vc finishing 250 – 290 220 – 260 f 0.10 – 0.30 0.10 – 0.30 Vc plunging/parting-off 160 – 240 140 – 220 f 0.15 – 0.50 0.15 – 0.50Plain turning – CNC Vc roughing 140 – 180 110 – 150(Carbide tooling, coated) f 0.05 – 0.35 0.05 – 0.30 Vc finishing 160 – 200 130 – 170 f 0.05 – 0.25 0.05 – 0.20 Vc plunging/parting-off 80 – 140 60 – 120 f 0.05 – 0.25 0.05 – 0.25Drilling Vc 120 – 180 110 – 170(Solid carb. drill) f 0.10 – 0.30 0.10 – 0.30Drilling Vc 60 – 100 50 – 90(HSS, coated) f 0.05 – 0.25 0.05 – 0.25Reaming Vc 30 – 40 30 – 40(HSS, coated) f 0.10 – 0.30 0.10 – 0.30External/internal threading Vc 70 –160 60 – 150(Chase threading, carbide/HSS, coated) Internal threading Vc 8 – 9 8 – 9(Cutting, carbide tooling, coated) Internal threading Vc 10 – 20 10 – 20(Forming, carbide tooling, coated)

Values as a function of machine and machining parameters

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Surface finish

The surface finish of ETG® 88/100 cor-

responds to the specifications in

EN 10277-1. ETG® 88/100 are tested for

cracks as standard. We guarantee a

surface finish of 3 for round bars and a

surface finish of 2 for hexagonal bars.

Please note that for a standard bar, the

ends of the bar (up to 50 mm) cannot be

tested.

If surface imperfections might cause prob-

lems (e.g. notch-stress concentration

effect with surface hardening), the surface

of the material must be removed to at

least the allowable depth of imperfection.

Non-cutting forming, thread rolling

Threads can be rolled on ETG®. However,

worms, trapezoidal threads, etc., should

be cut, not rolled.

Other non-cutting processes

Punching, bending, swaging, forging, etc.,

should not be carried out on ETG® 88

and ETG® 100.

Welding

ETG® 88/100 have a limited weldability.

Austenitic electrodes should be used and

it should be noted that the strength will

decrease significantly. The fracture strength

depends on the strength of the weld

metal. In order to avoid failures, we rec-

ommend carrying out tests before welding

the part itself. Best results are achieved

using tungsten inert gas (TIG) welding.

– Welding procedure: tungsten inert gas

– Welding consumable: X15CrNiMn 18-8

(1.4370)

– Preheat: 300 °C

– Tensile strength of the welded joint:

490 – 670 N/mm2

ETG® is not suitable for laser welding.

Brazing

ETG® can also be brazed, but with con-

sequent loss of strength. It must be

allowed to cool slowly, as there is a dan-

ger of stress cracks.

Surface finishing

Most surface finishes can be applied to

ETG® 88/100. For example, they can

be hot-galvanised, chromated, chromium-

plated, nickel-plated or alkaline-black -

ened without difficulty. Due to the man-

ganese sulphide in the steel, special care

must be taken when pickling and neu-

tralising. The temperature at which surface

finishing is carried out should not exceed

500 °C. Ground material is recommended.

For changes in mechanical properties, see

diagram of strength values on page 14.

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Information for heat-treating

ETG® steels

The high strength of ETG® steels lies in

the range of tempered steels, which

means that in most cases no additional

heat treatment is necessary. If greater

abrasion resistance or fatigue strength is

needed, various surface hardening proc-

esses can be used. The high basic

strength guarantees a good underlying

structure and ideally fulfils the pre-

requisites for the following heat treatment

processes:

– Induction hardening (high frequency)

– Nitrocarburising

– Salt bath nitrocarburising

– Gas nitrocarburising

– Plasma nitrocarburising

Induction hardening (HF)

– Treatment temperature: 840 – 870 °C

– Quenching media: oil, polymer

– Achievable hardness: 50 – 55 HRC

The depth of hardening should be kept

to a minimum, generally not more

than 1 mm. For complicated parts, an

initial stress-relieving at 550–580°C is

recommended. Using water as a quench

medium results in higher hardness,

however there is a danger that quench

cracking will occur.

Induction hardening (HF)Hardness pattern

700

650

600

550

500

450

400

350

300

0 1 2 3 4

Distance from surface [mm]

Mic

roha

rdne

ss H

V 0

,3

22

900

800

700

600

500

400

300

200

100

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Distance from surface [mm]

The hardness of the white layer cannot be measured for technical reasons. According to the literature, the hardness is approx. 1,000 HV.

Nitrocarburising Hardness pattern

Mic

roha

rdne

ss H

V 0

.25

23

Salt bath nitrocarburising

– Treatment temperature: 570 °C

– Treatment duration: 60 – 180 min

– The treatment time affects the thick-

ness of the hard compound layer.

– The usual treatment time is 90 min.

– Thickness of compound layer:

15 – 20 µm; the quenching medium

must be appropriate for the workpiece:

water (warm) for ø <15 mm, oil for

larger workpieces.

The bath nitrocarburising process creates

an abrasion-resistant surface. It also

reduces notch sensitivity and increases

fatigue strength for reverse bending. Salt

bath nitrocarburising results in a loss of

substrate strength amounting to approx.

10%. After bath nitrocarburising, no more

machining can be carried out. For this

reason, if high dimensional accuracy is re-

quired, the work piece must be stress-

relieved at 550 – 580 °C before final ma-

chining.

After bath nitrocarburising, it is advanta-

geous to remove salt residues from work-

piece surfaces by brushing.

Depth of decarburised zone(experimental values)

Dimension Decarburisation Ø ≤20 mm max. 0.20 mmØ >20 mm max. 0.40 mm

Gas nitrocarburising

– Treatment temperature: 570 °C

– Treatment duration: 1– 3 h

– Thickness of compound layer:

approx. 15 µm

– Quench medium: water, oil, gas

Pretreatment is the same as for bath

nitrocarburising. A similarly abrasion-

resistant surface is created. The process

results in a loss of substrate strength

amounting to approx. 10%.

Plasma nitrocarburising

– Treatment temperature: 480 – 510 °C

– Treatment duration: 20 – 36 h

– Thickness of compound layer:

approx. 10 µm

This process – glow-discharge nitrocar-

burising in a vacuum – has produced

good re sults with ETG®. Due to the lower

treatment temperature, there is less

reduc tion in the core strength than with

salt bath or gas nitrocarburising.

Recommendations

– Avoid hardening over sharp edges,

keyways or lateral holes.

– Do not harden thin-walled components

through the full thickness of the wall.

– End faces or spherically shaped areas

should be stress-relieved at 180 – 200 °C

before hardening.

– With induction hardening, avoid hard-

ening to a depth greater than 1 mm.

– Like all rolled-and-drawn material,

ETG® has a slightly decarburised

boundary zone, which means that the

hardening effect in this zone is re-

duced.

– When hardening gear wheels, the tooth

root should also be hardened to a

depth of 0.2 mm.

– Hardening of the drawn surfaces

should be avoided due to the possible

pres ence of surface imperfections. Due

to the notch effect, hardening stresses

at the imperfections can cause cracks.

– To avoid the occurrence of hardening

cracks due to hardening stresses,

the hardened components should be

tempered (200 °C, 1 h).

– There is less danger of hardness

cracks occurring in ETG® 88 than in

ETG® 100 due to its lower residual

stress.

– Depending on the nitrocarburising pro c-

ess employed, tempering at 350 °C

for at least 2 h may be necessary to

remove the hydrogen that has been

introduced.

The technical information contained in this document reflects current results obtained using generally accepted testing procedures on production quantities. They do not give a guarantee of the suitability for any particular application. The responsibility lies with the user.

© Steeltec AG, 07.07

Steeltec AGPostfach, CH-6021 EmmenbrückeTelephone ++41 41 209 63 63, fax ++41 41 209 52 94www.steeltec.ch

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