Case Hardening Steels

CARBODURCARBODUR

CARBODUR

Engineer ing steels

Case-hardening steels

EDELSTAHL WITTEN-KREFELD GMBH

CARBODURCARBODUR

CARBODUR

3

Contents

Page 4 – 7 Carbodur – The material

Page 8 – 9 Energy industry

Page 10 – 11 Transport

Page 12 – 13 General mechanical engineering

Page 14 – 15 Steel portraits

Page 16 – 17 Steel production

Page 18 – 19 Steel processing

Material data

Page 20 – 31 Material Data Sheets

(Please note the text on the flap of the rear cover, which contains

information on the Material Data Sheets)

Technical information

2 – 36 Hardenability

Page 37 – 39 Machining and heat treatment

Page 40 – 43 Case-hardening treatment

Page 44 Overview of grades and chemical composition

Page 45 Melt analysis/International standards

Page 46 Forms supplied

Page 47 Hardness comparison table

Page 48 Temperature Comparison

Page 50 List of photos

How long a component stands up

to demands, and how reliably it

withstands peak stresses, de-

pends on the material the compo-

nent is made of. In the final analy-

sis, the load-bearing capacity of a

small part determines the cost-

efficiency of large machines or

installations.

The more carefully the material is

tailored to the function of the re-

spective components, the more

efficient the entire system is.

Edelstahl Witten-Krefeld is the

specialist for producing high-

grade steels with highly specific,

precisely defined properties.

The group of case-hardening

steels marketed under the brand

name Carbodur is evidence of the

leading international position of

Edelstahl Witten-Krefeld in the

field of high-strength, high-grade

steels.

The case-hardening steels pre-

sented in this brochure are un-

alloyed and alloyed special

engineering steels with relatively

low carbon contents of roughly

0.10 to 0.25%.

4

In terms of non-metallic inclu-

sions, the purity of these steels is

higher than that of normal quality

steels. They also respond more

uniformly to heat treatment.

Through precise adjustment of

the chemical composition and the

use of special production and test

conditions, we are in a position to

supply you with steel grades

manufactured with a wide variety

of processing and service proper-

ties. Following carburising and

hardening of the surface, case-

hardening steels display great

hardness and wear resistance in

the region of the surface layer,

while the strength and toughness

of the base material are retained

in the core.

CARBODUR

Hard case, tough core –gets to grips

5

Consequently, case-hardening

steels or case-hardened compo-

nents are indispensable wherever

high wear resistance, high fatigue

strength and low notch sensitivity

are required.

The choice of a steel grade is

governed by the intended appli-

cation, the types of stress in-

volved and the dimensions of the

parts or the geometry of the com-

ponents in question. Technical

and economic aspects are like-

wise of decisive importance. Our

materials specialists are available

for consulations concerning the

optimum choice and most expe-

dient use of the various case-

hardening steel grades.

Carbodur – unbeatable for

hardness and durability

Carbodurwith wear problems

mostly of a tensile nature, and

thus increase the fatigue strength.

In addition to their extraordinary

wear resistance, components

made of Carbodur steels are thus

characterised by very high

strength under dynamic loads

once they have been hardened.

However, case-hardened compo-

Maximum purity

The strength and toughness of

the base material are determined

by its chemical composition and

the heat treatment it undergoes.

Consequently, the required prop-

erties of the steel are already spe-

cifically targeted when first melt-

ing the steel. The facilities in

Witten and Krefeld permit a highly

accurate and reliably repeatable

chemical composition. An ex-

tremely high degree of purity is

achieved by the spot-on melt

analysis, secondary metallurgical

treatment and vertical continuous

casting, or alternatively by remelt-

ing. Non-metallic inclusions are

virtually ruled out.

The high degre of macroscopic

and microscopic purity, the

homogeneity of the microstruc-

ture and the fine-grain stability of

our Carbodur grades cannot be

beaten by any other manufacturer

of high-grade steels.

Controlled hardenability

The selection of appropriate al-

loying elements permits targeted

control of the hardenability of the

base material and the hardenabil-

ity of the carburised surface layer.

In addition to unalloyed case-

hardening steels, we also offer

the following alloyed versions:

manganese-chrome case-harden-

ing steels, molybdenum-chrome

case-hardening steels, nickel-

chrome case-hardening steels,

6

nickel-chrome-molybdenum case-

hardening steels and chrome-

nickel-molybdenum case-harden-

ing steels.

The great hardness and the

fatigue strength of the surface

layer are achieved by the case-

hardening treatment, i.e. by car-

burising, hardening and temper-

ing (or stress relieving). If, for

example, high strength is required

in combination with high tough-

ness of the core, the alloying ele-

ments must be matched in such a

way that through-hardening is

guaranteed at a given cross-sec-

tion and with the given heat treat-

ment. This steel-specific through-

hardening is offered by Carbodur,

even at large cross-sections.

We are in a position to offer you

case-hardening steels manufac-

tured specifically with the hard-

ness you require. Make use of

this opportunity - talk to our

materials specialists!

High fine-grain stability

The targeted adjustment of the

aluminium and nitrogen contents

of our Carbodur steels results in

outstanding fine-grain stability.

Thanks to this high fine-grain sta-

bility, our steels are particularly

suitable for the direct hardening

of components, a process carried

out at high temperatures. Coarse-

grain or mixed-grain steel would

result in non-uniform distortion

and reduced toughness.

Spot-on right

High fatigue strength

Inherent compression stresses

arise in the surface layer when

case-hardening a component.

These stresses counteract the

external stresses, which are

7

– Carbodur has just thechemstry for you

nents also have to demonstrate

the highest possible ductility

when exposed to high dynamic

stresses, in order to avoid brittle

fractures. As the impact strength

of the component decreases with

increasing case-hardening depth,

the latter must not be too great.

Good machinability

The larger the quantity of compo-

nents to be manufactured, the

more important the demand for

good machinability of the materi-

al. This means that the economic

efficiency of series production is

already defined when ordering the

steel. The machinability of case-

hardening steels is influenced by

the microstructure, the strength

and the non-metallic inclusions

(sulphides, oxides) that may be

present. The machinability of the

steel can be further optimised by

increasing the amount of sulphid-

ic inclusions, by calcium treat-

ment and by appropriate heat

treatment, i.e. by specifically ad-

justing the microstructure.

Made-to-measure heat

treatment

Depending on the intended appli-

cation and processing, we can

supply you with Carbodur steel

grades in a wide variety of treated

conditions, e.g. with reduced

hardness, maximum hardness or

a specific hardness range, treated

for ferrite-pearlite structure or for

spherical carbides.

Detailed technical information on

forms supplied and machining

can be found from Page 32

onwards.

8

More staying with Carbodur

The world of Carbodur steels is

the world of drive systems. Their

strengths are in demand wherever

power is transmitted. The indi-

vidual components of the mighty

transmission mechanisms used in

hydroelectric power stations, wind

turbine generators or in the off-

shore industry not only have to

withstand enormous pressures per

unit of area, they also have to run

constantly and untiringly. This calls

for wear resistance and fatigue

strength. Precision gear wheels

made of Carbodur in the propeller

drives of drilling rigs and turbine

gears of power stations reliably

withstand the stresses and, thanks

to their wear resistance, reliably

guarantee the dimensional stability

of the components. Safety takes

top priority in the mining sector.

The underground extraction equip-

ment essentially works non-stop

without a break. Malfunctions

brought about by the failure of

transmission components not only

mean expensive interruptions in

production, but also increase the

safety risk.

Here, the emphasis is not so much

on resistance to impact and shock

loads as on hardness and core

strength. Our chrome/nickel or

chrome/nickel/molybdenum-

alloyed Carbodur grades, for ex-

ample, offer the best prerequisites

for meeting the stringent require-

ments. Our Carbodur 17 CrNi 6-6

and Carbodur 18 Cr NiMo 7-6

grades, for instance, are particu-

larly suitable for relatively large

cross-sections.

9

power – case-hardening steels

Carbodur –

takes more, lasts longer

Energy industry

10

Carbodur – the winnercomes

Just as there is a wide variety of

demands on the components for

different types of vehicle, we also

have a wide variety of options for

precisely adapting our Carbodur

steels to suit the prevaillign re-

quirements. The suitable material

for the components is selected

with a view to safety, economic

efficiency and a long service life,

or the ability to withstand extreme

stresses for short periods.

The differential of a Formula 1 car,

for example, only has to withstand

stress for a relatively short time -

the duration of a race (at least!).

On the other hand, it is exposed to

extreme stresses for short periods

of time as a result of the enormous

torques transmitted. Carbodur

steel can be specifically “tuned” to

cope with this task.

In contrast, the gear wheels of a

truck that works under the tough

conditions of a building site have

to take constant punishment over

long periods, and must also be

capable of absorbing sudden

blows and shocks without losing

any teeth. The case-hardened

parts have to display a combina-

tion of wear resistance and fatigue

strength in the surface layer and

impact strength in the core zone.

Safety takes top priority in the

passenger transport sector. Con-

sequently, the specific properties

of Carbodur steels are particularly

advantageous for engines and

gearboxes in automotive engi-

neering. They can be used, for

example, in piston pins, speed

change gears, drive shafts, coun-

tershafts, synchroniser bodies,

ring gears, differential bevel gears,

bevel pinions and differential side

gears.

11

when itto extreme stresses

Carbodur – hard for the moment

and for the duration

Transport

12

Carbodur case-hardening the prescription Maximum precision on the one

hand, and maximum sturdiness on

the other – two different require-

ments, but always one task for

Carbodur. In terms of precision, a

printing press is like a giant clock-

work: screen resolutions of as little

as 0.01 mm are required in order

to produce the finest prints. The

numerous gear wheels of the indi-

vidual printing units have to be

manufactured to very close toler-

ances. Wear means play in the

wheelwork and impairs the quality

of the resultant prints. Therefore,

the gear wheels and the individual

assemblies of high-quality printing

presses have to be manufactured

using a steel grade that is already

melted to have a specific chemical

composition catering to the re-

quirements, or that is produced for

specific hardenability. The steel, or

the individual components, must

be strong at the core, while the

surface layer must withstand any

wear whatsoever. And it has to do

so at very high speeds and for

years on end. It would not be a

good idea to use the same steel in

heavy-duty transmissions, e.g. in

the mining industry or in an exca-

vator, if only because of the larger

dimensions or the machines, or of

the gear wheels and other compo-

nents. The drivelines of mining

machines and construction ma-

chinery have to withstand gigantic

stresses. A breakdown caused by

a broken tooth, for instance, can

cause expensive production stop-

pages. Edelstahl Witten-Krefeld

not only supplies you with the

optimum steel grade for large

cross-sections, or bar stock with

large dimensions, but also acts as

your extended workbench, as it

were, by providing pre-machined

parts, such as pre-drilled disks.

Talk to our specialists about these

options.

und

13

steels – against bad teeth

Carbodur – für den Moment

d auf Dauer

Prevention with Carbodur –

better than false teeth

General mechanical engineering

14

How would you like it – whole or

Large cross-sections

Carbodur – definitely not run-of-

the-mill, but specifically tailored to

your needs. Each of the basic

grades briefly outlined here can

be heat treated at the factory to

adapt it for optimum machining

and/or the minimum possible

distortion during case-hardening.

Above all, we are also in a posi-

tion to supply these steel grades

in the form of bar stock with large

cross-sections and also in various

processed stages. For example:

disks sawn from bars, either with

or without a drilled hole. Our pro-

duction capabilities also include

parts individually forged to shape.

The range of processing options

goes all the way to bright surfaces

with close tolerances.

Pre-machined to taste

Make use of our wide-ranging

capabilities and let us act as your

extended workbench. Talk to our

specialists. They can work with

you in devising an individual solu-

tion to meet your needs.

• Carbodur C 15 E/Carbodur C 15 R

Unalloyed case-hardening steel for com-

ponents in mechanical and automotive

engineering with low core strength, pri-

marily for wear stresses, such as levers

and shafts.

15

sliced?

Carbodur – metallurgical

delicacies à la carte

• Carbodur 16 MnCr 5

• Carbodur 16 MnCrS 5

CrMn-alloyed case-hardening steel for

components in mechanical and automotive

engineering with relatively high core

strength, e.g. relatively large piston pins,

camshafts and gear wheels

• Carbodur 15 NiCr 13

NiCr-alloyed case-hardening steel for highly

stressed components in mechanical engi-

neering with high demands on toughness

at low temperatures.

• Carbodur 17 Cr 3

Cr-alloyed case-hardening steel for compo-

nents in mechanical and automotive engi-

neering with low core strength, primarily for

wear stressed, e.g. piston pins and cam-

shafts

• Carbodur 17 CrNi 6-6

CrNi-alloyed case-hardening steel for high-

ly stressed components in mechanical and

automotive engineering with high strength

and toughness at relatively large cross-

sections, such as bevel pinions, pinion

gears, shafts, pins and countershafts

• Carbodur 18 CrNi 8

CrNi-alloyed case-hardening steel for high-

ly stressed components in mechanical and

automotive engineering with very high

strength and toughness at relatively large

cross-sections, such as bevel pinions, pin-

ion gears, shafts, pins and countershafts

• Carbodur 18 CrNiMo 7-6

CrNiMo-alloyed case-hardening steel for

heavy-duty and highly stressed transmis-

sion components in mechanical engineer-

ing with high demands on toughness, e.g.

gear wheels, pinion gears and worm shafts

• Carbodur 20 NiMoCrS 6-5

NiMoCr-alloyed case-hardening steel for

highly stressed components in mechanical

and automotive engineering with high strength

and toughness, e.g. bevel pinions, pinion

gears, shafts, pins and countershafts

• Carbodur 20 MnCr 5

• Carbodur 20 MnCrS 5

CrMn-alloyed case-hardening steel for


engineering with relatively high core strength,

e.g. gear wheels, ring gears, main shafts

and countershafts

• Carbodur 20 MoCr 4

• Carbodur 20 MoCrS 4

MoCr-alloyed case-hardening steels for



e.g. gear wheels, ring gears, main shafts

and countershafts

• Carbodur 20 NiCrMo 2-2

• Carbodur 20 NiCrMoS 2-2

NiCrMo-alloyed case-hardening steel for



e.g. gear wheels, spiders and ball cages

• Carbodur 22 CrMoS 3-5

CrMo-alloyed case-hardening steel for



e.g. gear wheels, ring gears, shafts and

spiders

Steel portraits

16

We make our own recipes Our own steel production in our

modern steelworks in Witten is

the basis for the purity and homo-

geneity of our case-hardening

steels. Precisely defined proper-

ties are achieved by means of

exact alloying and process

specifications for smelting, shap-

ing and heat treatment. The steels

are smelted in a 130 t electric arc

furnace.

The metallurgical precision work

is performed in a downstream

ladle furnace of the same size.

Depending on the steel grade and

the dimensions of the end prod-

uct, the steel melted in this way is

cast in ingots or continuous cast

blooms. Over 50 different mould

formats are available for ingot

casting, ranging from 600 kg to

160 t.

The continuous cast blooms are

manufactured in two strands on a

vertical continuous casting ma-

chine in a 475 x 340 mm format.

A remelting steelworks with two

electroslag remelting (ESR) fur-

naces and two vacuum arc re-

melting (VAR) furnaces is avail-

new ingot. In addition, the slag

has a high capacity for absorbing

non-metallic inclusions, which

means that the remelted material

is free of coarse inclusions. The

improvement in the microscopic

purity is attributable to desulphur-

isation and the resultant high

able in Krefeld for the production

of case-hardening steels involving

particularly stringent demands in

terms of homogeneity, toughness

and purity.

Electroslag remelting process

In the electroslag remelting pro-

cess (ESR), which works with al-

ternating current, a cast or forged,

self-consuming electrode is im-

mersed in a bath of molten slag,

which serves as an electrical resis-

tor.

The material to be remelted drips

from the end of the electrode

through the slag and forms the

new ingot in a water-cooled

mould below. The heat dissipa-

tion leads to directional solidifica-

tion in the direction of the longitu-

dinal ingot axis.

The remelting slag fulfils several

functions in this process. On the

one hand, it develops the neces-

sary process heat, while at the

same time supporting chemical

reactions, such as desulphurisa-

tion, and acting as an anti-

oxidant for the melting bath of the

Scrap 130-t-electricarc furnace

Ladle degas-sing station(VD/VOD)

Remelting facilities

ESR

VAR

EDELSTAHL WITTEN-KREFELD GMBH

THYSSEN KRUPP STAHL AG

Main production routes

Ladlefurnace

17

steel, using reliableand the best ingredients

degree of sulphidic purity, and

also to a reduction in the size and

quantity of oxidic inclusions.

Carbodur – technological

precision from the start

Steel production

ontinuous bloomer, 475 x 340 mm,

2 strands

Blooming/billet/large-sizebar rolling mill

Untreated

As-rolled

LSX 25

33 MN pressLSX 55

Long forging machines

As-forged

Finishingdepartments,rolling mills

Finishingdepartments,forging shops

Heattreatmentfacilities

Blooming-slabbing mill

ot casting

Machining

Products

Peelingmachines

• As-cast ingots As-continuously cast bloom material

• Open-die forgingsas-forged or machined

• Forged semis

• Forged round billets for tubemakingas-forged or peeled

• Forged bar steelas-forged or machined

• Machined tool steelforged or rolled

• Rolled semis

• Rolled tube roundsas-rolled or peeled

• Rolled bar steelas-rolled or machined

• Universal plate and flats

• Special products

18

Carbodurtailored to suit

Vacuum arc remelting process

The vacuum arc remelting (VAR)

process works with cast or

forged, self-consuming elec-

trodes in a vacuum.

Using an electric arc in a vacuum,

a melting bath is generated in a

copper crucible, which acts as

the opposite pole to the remelting

electrode and is connected to a

DC voltage source via current

contacts.

A new ingot is formed from the

liquefied electrode material drop

by drop in a continuous process.

In the VAR process, refinement of

the steel is brought about by the

reaction of the oxygen dissolved

in the steel with the carbon in the

molten material under the effect

of the vacuum. This results in the

best possible degree of micro-

scopic oxidic purity and freedom

from macroscopic inclusions. As

no desulphurisation takes place

during this remelting process, the

lowest possible sulphur content

has to be set prior to remelting, in

order also to meet the most strin-

gent demands on the degree of

sulphidic purity. Moreover, this

process guarantees the lowest

possible quantities of dissolved

gases in the steel and a minimum

of segregation.

Steel processing

The blooming mill in Witten pro-

duces semi-finished products,

steel bars and wide flats. Two

modern finishing lines for check-

ing the inner and outer surface

condition, as well as the dimen-

sions and identity, are available

for rolled and forged products

and steel bars. The forge is

equipped with a 33 MN press, a

GFM LSX 55 horizontal long forg-

ing machine and a GFM LSX 25

long forging machine.

19

– Steels preciselyyour applications

We work ahead

for your benefit

Steel processing

Cooling

Water (oil),

Hot bath 160 � 250 °C, case-hardening box, air 4)

Water (oil), hot bath 160 � 250 °C 4)



Air

1

4539

2

4235

3

3531

4

3327

5

3225

6

2822

7

2620

8

24�

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining

Tempering (stress-relieving) 5)

CARBODUR® C 15 E / C 15 R

C

0.12�0.180.12�0.18

Si

≤0.40≤0.40

Mn

0.30�0.600.30�0.60

P

≤0.035≤0.035

S

≤0.0350.020�0.040

C 15 EC 15 R

Material No.Code

Chemicalcomposition

Heat treatments

Typical analysis in %

Hmax.min.

Treated forshearing S

HB

1)

Material No.

1.1141

Designation

C15E

Material No.

1.1140

Designation

C15R

Treatedfor strength TH

HB

Soft-annealed A

HB

max. 143

Treated for ferrite-pearlite structure FP

HB

Annealed to sphericalcarbides AC

HB

max. 135

Treatment temperature

880 � 980 °C

880 � 980 °C

880 � 920 °C

780 � 820 °C

150 � 200 °C

Hardness in varioustreatment conditions

Hardenability in theend-quench test

Hardness in HRC

Hardenability diagram

55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45

Abstand von der abgeschreckten Stirnfläche in mm

Här

te in

HR

C

Distance from the quenched end in mm

See flap for footnotes

20

Har

dne

ss in

HR

C

Distance from quenched end in mm

Cooling

Oil (water), hot bath 160 � 250 °C,

Salt bath (580 � 650 °C), case-hardening box, air 4)

Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Air

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining


C

0.14�0.20

Si

≤ 0.40

Mn

0.40�0.70

P

≤0.035

S

≤0.035

Cr

0.60�0.90

Ni

3.60�3.50

Material No.Code

Chemicalcomposition

1.5

4841

4843

4641

3

4841

4843

4641

5

4841

4843

4641

7

4740

4742

4540

9

4538

4540

4338

11

4436

4439

4136

13

4233

4236

3833

15

4130

4134

3730

20

3824

3829

3324

25

3522

3526

3122

30

3422

3426

3022

35

3421

3425

3021

40

3321

3325

2921

Hmax.min.

HHmax.min.

HLmax.min.


880 � 980 °C

880 � 980 °C

840 � 880 °C

780 � 820 °C

150 � 200 °C

Material No.

1.5752

Designation

15NiCr13

CARBODUR® 15 NiCr 13


HB

max. 255

Treated for strength TH*

HB

179 � 229

Soft-annealed A

HB

max. 229

Treated for ferrite-pearlite structure FP**

HB

166 � 217


HB

max. 180


Heat treatments

* For diameters up to 150 mm** For diameters up to 60 mm



Hardness in HRC

Hardenability diagram Time-temperature-transformation diagramfor continuous cooling

503090 50 20 15

45

70 75 7575

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

100 101 102 103 104

100 101 102

HV 10

M

BMs

AC3

AC1

90 95

5

8

15

7515 25

A F

P

106

360 352 328 313 282 277 261 245 231 228 227 192 169

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

Härtewerte

55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C

HH-SorteÜberschneidungHH+HL-Sorte

HL-Sorte



21

Har

dne

ss in

HR

C


HH gradeOverlap ofHH + HL grade

HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardness values


Heat treatments



Hardness in HRC


Cooling



Oil (water), hot bath 160 � 250 °C 4)



Air

1.5

4739

4742

4439

3

4636

4639

4336

5

4431

4435

4031

7

4128

4132

3728

9

3924

3929

3424

11

3721

3726

3221

13

35�

3524

30�

15

33�

3322

28�

20

31�

3120

26�

25

30�

30�

25�

30

29�

29�

24�

35

28�

28�

23�

40

27�

27�

22�

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining


CARBODUR® 16 MnCr 5 / 16 MnCrS 5

C

0.14�0.190.14�0.19

Si

≤0.40≤0.40

Mn

1.10�1.301.10�1.30

P

≤0.035≤0.035

S

≤0.0350.020�0.040

Cr

0.80�1.100.80�1.10

16 MnCr 516 MnCrS 5

Material No.Code

Chemicalcomposition

Hmax.min.

HHmax.min.

HLmax.min.



880 � 980 °C

880 � 980 °C

860 � 900 °C

780 � 820 °C

150 � 200 °C

Material No.

1.7131

Designation

16MnCr5

Material No.

1.7139

Designation

16MnCrS5


HB

1)


HB

156 � 207

Soft-annealed A

HB

max. 207


HB

140 � 187


HB

max. 165

2010

5040

85

B

FP

M

MS 9780

7765

AC1

AC3

10081

50

3 1520 60 65

3540

37

93

53

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

A

106

HV 10

100 101 102 103 104

100 101 102

10

5030

35

1530

60

394 317 278 251 243 221 207 199 187188

182 170 156

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

Härtewerte

55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte



22

Har

dne

ss in

HR

C



HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardness values

Cooling

Wasser (Öl),

Hot bath 160 � 250 °C, case-hardening box, air 4)




Air

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining


CARBODUR® 17 Cr 3

C

0.14�0.20

Si

≤0.40

Mn

0.60�0.90

P

≤0.035

S

≤0.035

Cr

0.70�1.00

Material No.Code

Chemicalcomposition


1.5

4739

4742

4439

3

4435

4438

4135

5

4025

4030

3525

7

3320

3324

2920

9

29�

2920

25�

11

27�

27�

23�

13

25�

25�

21�

15

24�

24�

20�

20

23�

23�

��

25

21�

21�

��

Hmax.min.

HHmax.min.

HLmax.min.

Material No.

1.7016

Designation

17Cr3


880 � 980 °C

880 � 980 °C

860 � 900 °C

780 � 820 °C

150 � 200 °C


HB

1)

Treatedfor strength TH

HB

Soft-annealed A

HB

max. 174

Treated for ferrite-pearlite structure FP

HB


HB

max. 155

Heat treatments



Hardness in HRC


3070 75

252515

1

3

67

20

F

M

MS 1565

15

AC1

AC3

35

5

20

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

A

106

HV 10

100 101 102 103 104

100 101 102

B85

1 5 3P

7572

446

439368 297 236 206

181160 151 141

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

Härtewerte

55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte



23

Har

dne

ss in

HR

C



HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardnessvalues

Cooling



Air, furnace



Air

Type of treatment

Case-hardening

Carburising 2)

Intermediate annealing

Core refining

Case refining


CARBODUR® 17 CrNi 6-6

C

0.14�0.20

Si

≤0.40

Mn

0.50�0.90

P

≤0.035

S

≤0.035

Cr

1.40�1.70

Ni

1.40�1.70

Material No.Code

1.5

4739

4742

4439

3

4738

4741

4438

5

4636

4639

4336

7

4535

4538

4235

9

4332

4336

3932

11

4230

4234

3830

13

4128

4132

3728

15

3926

3930

3526

20

3724

3728

3324

25

3522

3526

3122

30

3421

3425

3021

35

3420

3425

2920

40

3320

3324

2920

Hmax.min.

HHmax.min.

HLmax.min.


880 � 980 °C

630 � 650 °C

830 � 870 °C

780 � 820 °C

150 � 200 °C

Material No.

1.5918

Designation

17CrNi6-6


HB

max. 255


HB

175 � 229

Soft-annealed A

HB

max. 229


HB

156� 207


HB

max. 178


Chemicalcomposition

Heat treatments




Hardness in HRC


10

100 9790

35

6540

M

MS

AC1

AC3

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

A

106

HV 10

100 101 102 103 104

100 101 102

100

100

100

100 9585 70

3 515 30

55 60 70 75

10 3525

35 30

F

P

5

B100

60

409

394

357

318

297

276

270

266

262

242

222

203

175

161

157

154

154Härtewerte

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte



24

Har

dne

ss in

HR

C



HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardness values

M

MS

AC1

AC3

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

A

106

HV 10

100 101 102 103 104

100 101 102

100 100 100 95 90 70

3030 5F P

65100

B

105

429 425 417 425 390 363 342 333 312 312 312 268 249Härtewerte

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

Cooling



Air, furnace



Air

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining


C

0.15�0.20

Si

0.15�0.40

Mn

0.40�0.60

P

≤0.035

S

≤0.035

Cr

1.80�2.10

Ni

1.80�2.10

Material No.Code

Chemicalcomposition

1.5

4941

4944

4641

3

4941

4944

4641

5

4940

4943

4640

7

4939

4942

4639

9

4939

4942

4639

11

4938

4942

4538

13

4937

4941

4537

15

4936

4940

4536

20

4835

4839

4435

25

4735

4739

4335

30

4734

4738

4334

35

4634

4638

4234

40

4633

4637

4233

Hmax.min.

HHmax.min.

HLmax.min.


900 � 950 °C

630 � 650 °C

840 � 870 °C

800 � 830 °C

170 � 210 °C

Material No.

1.5920

Designation

18CrNi8

CARBODUR® 18 CrNi 8


HB

max. 255


HB

199 � 229

Soft-annealed A

HB

max. 225


HB

158� 205


HB

max. 180


Heat treatments




Hardness in HRC


55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte


Time-temperature-transformation diagramfor continuous cooling


25

Har

dne

ss in

HR

C



HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardness values

30

97 95

90

M

MS

AC1

AC3

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

A

106

HV 10

100 101 102 103 104

100 101 102

60 80

80 55 15

F

5

B

3

100 100 100 100 100

5 2045 55 65

30 P

426425

418383

360343

336327

314 286261

242215 175

Härtewerte

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

Cooling



Air, furnace



Air

1.5

4840

4843

4540

3

4840

4843

4540

5

4839

4842

4539

7

4838

4841

4538

9

4737

4740

4437

11

4736

4740

4336

13

4635

4639

4235

15

4634

4638

4234

20

4432

4436

4032

25

4331

4335

3931

30

4230

4234

3830

35

4129

4133

3729

40

4129

4133

3729

Type of treatment

Case-hardening

Carburising 2)


Core refining

Case refining


CARBODUR® 18 CrNiMo 7-6

C

0.15�0.21

Si

≤0.40

Mn

0.50�0.90

P

≤0.035

S

≤0.035

Cr

1.50�1.80

Ni

1.40�1.70

Mo

0.25�0.35

Material No.Code

Chemicalcomposition

Hmax.min.

HHmax.min.

HLmax.min.


880 � 980 °C

630 � 650 °C

830 � 870 °C

780 � 820 °C

150 � 200 °C

Material No.

1.6587

Designation

18CrNiMo7-6


HB

max. 255


HB

179 � 229

Soft-annealed A

HB

max. 229


HB

159� 207


HB

max. 180


Heat treatments




Hardness in HRC


55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte



26

Har

dne

ss in

HR

C



HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardness values

Cooling



Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Air

1.5

4939

4942

4639

3

4939

4942

4639

5

4838

4841

4538

7

4737

4740

4437

9

4636

4639

4336

11

4535

4538

4235

13

4433

4437

4033

15

4432

4436

4032

20

4230

4234

3830

25

4128

4132

3728

30

3926

3930

3526

35

3825

3829

3425

40

3823

3828

3323

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining


C

0.18�0.28

Si

max. 0.40

Mn

0.50�0.70

P

≤0.035

S

0.020�0.040

Cr

0.65�0.85

Ni

1.50�1.90

Mo

0.25�0.40

Material No.Code


Hmax.min.

HHmax.min.

HLmax.min.


900 � 950 °C

870 � 900 °C

840 � 870 °C

800 � 830 °C

170 � 210 °C

Material No.

1.6757

Designation

20NiMoCrS6-5

CARBODUR® 20 NiMoCrS 6-5


HB

max. 255


HB

170 � 220

Soft-annealed A

HB

max. 220


HB

155 � 205


HB

max. 180

Chemicalcomposition

Heat treatments




Hardness in HRC


310

M

MS

90

AC1

AC3

530

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

A

106

HV 10

100 101 102 103 104

100 101 102

89

153

87

7225

15

35

48 50

-P-F

B

85858580205

3

43

50

468

468 468 442 421 383 297 297 285 274 254 236 221 206 181 160

Härtewerte

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte



27

Har

dne

ss in

HR

C



HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardnessvalues

Cooling

Oil (water), hot bath 160 � 250 °C, 4)





Air

1.5

4941

4944

4641

3

4939

4942

4639

5

4836

4840

4436

7

4633

4637

4233

9

4330

4334

3930

11

4228

4233

3728

13

4126

4131

3626

15

3925

3930

3425

20

3723

3728

3223

25

3521

3526

3021

30

34�

3425

29�

35

33�

3324

28�

40

32�

3223

27�

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining


C

0.17�0.220.17�0.22

Si

≤0.40≤0.40

Mn

1.10�1.401.10�1.40

P

≤0.035≤0.035

S

≤0.0350.020�0.040

Cr

1.00�1.301.00�1.30

20 MnCr 520 MnCrS 5

Material No.Code

Hmax.min.

HHmax.min.

HLmax.min.



880 � 980 °C

880 � 980 °C

860 � 900 °C

780 � 820 °C

150 � 200 °C

Material No.

1.7147

Designation

20MnCr5

Material No.

1.7149

Designation

20MnCrS5

CARBODUR® 20 MnCr 5 / 20 MnCrS 5


HB

1)


HB

170 � 217

Soft-annealed A

HB

max. 217


HB

152 � 201


HB

max. 180

Chemicalcomposition


Heat treatments



Hardness in HRC


4040 40

10

60

60

B

F

M

MS 5065

55

45

AC1

AC3

8780

6065

35

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

A

106

100 101 102 103 104

100 101 102

15

25

40

5040

35

6060

25 P

60

405 342 302 274 263 238 212 187 171 160 182 162 153

HV 10

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

Härtewerte

55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte



28

Har

dne

ss in

HR

C



HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardness values

30 30

90

B

M

MS95

9585 70

AC1

AC3

9595

5

60 65

3015

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

A

106

HV 10

100 101 102 103 104

100 101 102

15

6555

3025

10 5 5 5

3 5 1065

30

70

30

70

30P

F

370 283 260 240 238 228 210 189 176 165 181156

152149

Härtewerte

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

Cooling

Oil (water), hot bath 160 � 250 °C,4)

Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Air

1.5

4941

4944

4641

3

4737

4740

4437

5

4431

4435

4031

7

4127

4132

3627

9

3824

3829

3324

11

3522

3526

3122

13

33�

3324

29�

15

31�

3122

27�

20

28�

28�

24�

25

26�

26�

22�

30

25�

25�

21�

35

24�

24�

20�

40

24�

24�

20�

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining


CARBODUR® 20 MoCr 4 / 20 MoCrS 4

C

0.17�0.230.17�0.23

Si

≤0.40≤0.40

Mn

0.70�1.000.70�1.00

P

≤0.035≤0.035

S

≤0.0350.020�0.040

Cr

0.30�0.600.30�0.60

Mo

0.40�0.500.40�0.50

20 MoCr 420 MoCrS 4

Material No.Code

Chemicalcomposition

Hmax.min.

HHmax.min.

HLmax.min.


880 � 980 °C

880 � 980 °C

860 � 900 °C

780 � 820 °C

150 � 200 °C

Material No.

1.7321

Designation

20MoCr4

Material No.

1.7323

Designation

20MoCrS4


HB

1)


HB

156 � 207

Soft-annealed A

HB

max. 207


HB

140 � 187


HB

max. 165


Heat treatments




Hardness in HRC


55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte



29

Har

dne

ss in

HR

C



HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardness values

1

5 5

40 55 60

84

B

M

MS

65

AC1

AC3

85

91

1200

1100

1000

900

800

700

600

500

400

300

200

100

0100 101 102 103 104 105

A

106

HV 10

100 101 102 103 104

100 101 102

75

40

F

97

96

7949

5

P2525

75

40101

1510

5

453453

453 426 313 283 276 245 239

234

210 182 159 148 140

Härtewerte

Tem

per

atur

in o

C

Zeit in s

Zeit in min

Zeit in h

Cooling



Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Air

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining


CARBODUR® 20 NiCrMo 2-2 / 20 NiCrMoS 2-2

C

0.17�0.230.17�0.23

Si

≤0.40≤0.40

Mn

0.65�0.950.65�0.95

P

≤0.035≤0.035

S

≤0.0350.020�0.040

Cr

0.35�0.700.35�0.70

Ni

0.40�0.700.40�0.70

Mo

0.15�0.250.15�0.25

20 NiCrMo 2-220 NiCrMoS 2-2

Material No.Code

Chemicalcomposition

1.5

4941

4944

4641

3

4837

4841

4437

5

4531

4536

4031

7

4225

4231

3625

9

3622

3627

3122

11

3320

3324

2920

13

31�

3122

27�

15

30�

3021

26�

20

27�

27�

23�

25

25�

25�

21�

30

24�

24�

20�

35

24�

24�

20�

40

23�

23�

��

Hmax.min.

HHmax.min.

HLmax.min.


880 � 980 °C

880 � 980 °C

860 � 900 °C

780 � 820 °C

150 � 200 °C

Material No.

1.6523

Designation

20NiCrMo2-2

Material No.

1.6526

Designation

20NiCrMoS2-2


HB

1)


HB

161 � 212

Soft-annealed A

HB

max. 212


HB

149 � 194


HB

max. 176


Heat treatments




Hardness in HRC


55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte



30

Har

dne

ss in

HR

C



HL grade

Tem

per

atur

e in

°C

Time in s

Time in min

Time in h

Hardnessvalues

Cooling



Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Oil, hot bath 160 � 250 °C 4)

Air

Type of treatment

Case-hardening

Carburising 2)

Direct hardening 3)

Core refining

Case refining


C

0.19�0.24

Si

≤0.40

Mn

0.70�1.00

P

≤0.035

S

0.020�0.040

Cr

0.70 �1.00

Mo

0.40�0.50

Material No.Code

Chemicalcomposition


880 � 980 °C

880 � 980 °C

860 � 900 °C

780 � 820 °C

150 � 200 °C

Material No.

1.7333

Designation

22CrMoS3-5

CARBODUR® 22 CrMoS 3-5


HB

max. 255


HB

170 � 217

Soft-annealed A

HB

max. 217


HB

152 � 201


HB

max. 180


Heat treatments




Hardness in HRC


1.5

5042

5045

4742

3

4941

4944

4641

5

4837

4841

4437

7

4733

4738

4233

9

4531

4536

4031

11

4328

4333

3828

13

4126

4131

3626

15

4025

4030

3525

20

3723

3728

3223

25

3522

3526

3122

30

3421

3425

3021

35

3320

3324

2920

40

32�

3223

28�

Hmax.min.

HHmax.min.

HLmax.min.

55

50

45

40

35

30

25

20

150 5 10 15 20 25 30 35 40 45


Här

te in

HR

C


HL-Sorte



31

Har

dne

ss in

HR

C



HL grade

32

Hardenability

Effect of alloying elements

on hardenability

Based on the composition of the

alloys, case-hardening steels can

be classified as:

• unalloyed

• chrome-alloyed

• manganese-chrome and molyb-

denum-chrome-alloyed

• nickel-chrome-alloyed

• nickel-chrome-molybdenum-

alloyed and

• chrome-nickel-molybdenum-

alloyed case-hardening steels.

The alloying elements affect the

hardenability of the base material

and the hardenability of the car-

burised surface layer.

The hardenability of the base

material is identified by means of

the end-quench test according to

DIN 50 191 and is an important

parameter for determining

hardness in the core, since case-

hardened components are only

tempered at low temperatures, up

to approximately 180 °C, in order

to ensure high surface hardness.

Fig. 1 shows an example of the ef-

fect of alloying elements on the

hardenability of various case-

hardening steels according to

DIN 10 084 in the end-quench

test. The hardness at a distance

of 1.5 mm from the end surface is

largely determined by the carbon

content. The shape of the rest of

the end-quench test curve is also

influenced by the quantities of

other elements, such as molyb-

denum, manganese, chrome and

nickel, that tend to increase hard-

enability. Given small cross-

sections, through-hardening is

possible with chrome or chrome-

manganese steels, while higher

quantities of molybdenum and

nickel must be added to

achieve through hardening

of large cross-sections.

For reasons of toughness, the

carbon content is limited to about

0.25%. The element silicon also

increases hardenability. It is, how-

ever, hardly ever used as an alloy-

ing element in case-hardening

steels because it encourages sur-

face oxidation on carburising. In

special cases, boron is used as

an alloying element to increase

hardenabililty or impact tough-

ness in chrome-manganese

steels.

In the case of some unalloyed

case-hardening steels, the effect

of a coarse-grain austenite struc-

ture is used to increase hardness.

Har

dne

ss in

HR

C


case-hardening steels50

40

30

20

10

0 10 20 30 40 50

18 CrNiMo 7-6

17 CrNi 6-6

20 MoCr 4

16 MnCr 5

17 Cr 3

Fig. 1Effect of alloying elements

on the hardenability of case-hardening steels

33


Quite apart from their influence

on hardness in the core, the

hardness and the hardness profile

in the carburised surface layer

have an important effect on the

properties of case-hardened

components. A surface hardness

of 57 - 63 HRC has proved to the

best for optimum wear resistance.

This degree of hardness is

achieved largely independently of

the steel composition, with a car-

bon content at the surface of

some 0.7%. Higher carbon con-

tents in the surface layer provide

only a slight increase in hardness.

Supercarburisation in the surface

layer may result in reduced

toughness due to precipitation of

secondary cementite and a

hardness loss caused by increas-

ing proportions of residual aus-

tenite.

The case depth, defined as the

distance from the surface of a

case-hardened workpiece to the

point whose Vickers hardness is

usually 550 HV1 (see DIN 50 190),

is determined by the depth of

carburisation, the heating and

cooling conditions during hard-

ening and the hardenability in the

carburised surface layer.

Correlations valid for the base

material cannot be applied to the

hardenability of the surface layer,

since the effect of alloying ele-

ments on hardenability also

depends on the carbon content.

Up to a carbon content of about

0.5%, the improvement in harden-

ability brought about by molyb-

denum, chrome and manganese

increases, only to drop again at

higher carbon contents.

Fig. 2 shows the case depth of

various case-hardening steels

with the same carbon distribution

in the surface layer. According to

this, case depth of the 17 Cr 3

steel (0.80 mm) is doubled in the

17 CrNi 6-6 steel (1.56 mm) due to

the different alloy contents under

otherwise identical conditions.

Distance from the surface in mm

Car

bon

con

tent

in %

by

wei

ght

%

0.90

0.80

0.70

0.60

0.50

0.40

0.30

0.20

0.10

00 0.4 0.8 1.2 1.6 2.0 2.4 2.8

17 Cr 320 NiCrMo 2-220 MoCr 416 MnCr 520 NiMoCr 6-517 CrNi 6-6

C

0.46 1.50 mm

0.39

0.340.37

0.330.35 % C

Eht

0.80

1.16

1.35

1.52

1.56

1.42

0.60

(acc. to U. Wyss)

Fig. 2: Case depth of various case-harden-ing steels with the same carbon profile(acc. to U. Wyss)

Suitability for direct

hardening

An important criterion in the

choice of a case-hardening steel

is its suitability for direct harden-

ing. The most common methods

of case hardening are direct hard-

ening (Fig. 10, Hardening from the

carburisation heat) and single

hardening after cooling from the

case (Fig. 11). Mainly for reasons

of cost effectiveness, direct hard-

ening is increasingly being given

preference in mass production

methods (see chapter on Heat

Treatment).

The prerequisites for the suitability

of a case-hardening steel for

direct hardening are satisfactory

fine-grain stability at the carburis-

ing temperature and low residual

austenite after hardening. The

residual austenite content after

hardening increases with increas-

ing chrome content and carburis-

ing temperature. Fig. 3 illustrates

this relationship, using the

20 MoCr 4, 20 NiMoCr 6 5,

16 MnCr 5, 20 MnCr 5,

17 CrNi 6-6 and 18 CrNi 8

steels as examples.

Although differences in the

proportions of residual aus-

tenite in the various steels

remain relatively small at carbu-

rising temperatures around 900 °C

with subsequent direct hardening,

they increase rapidly and pro-

gressively at higher carburising

temperatures. For economic rea-

sons, however, ever higher car-

burising temperatures are being

aimed at for direct hardening.

Given the same carburising time

and the same carbon potential in

the carburising medium, the pro-

portion of residual austenite in

the 17 CrNi 6-6 and 18 CrNi 8

steels with 1.6 to 1.8% chrome is

appreciably higher than, for exam-

ple, in the 20 MoCr 4 steel with

approximately 0.4% chrome. The

hardness decreases at carbon

contents > 0.7% at the surface,

which increases the proportions

of residual austenite (Fig. 4).

The suitability of a steel for direct

hardening can also be identified

by the range of carbon contents

at the surface with which a cer-

tain minimum hardness can be

achieved. According to this, the

20 MoCr 4 steel is more suitable

for direct hardening than, for

example, the 18 CrNi 8 steel.

Advances in the development of

modern gas carburising plants,

Chrome content in % by weight

Res

idua

l aus

teni

te c

onte

nt in

%

Carborisingtemperaturein °C:

Carborising time: 3 h100

90

80

70

60

50

40

30

20

10

00.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

1000

950

900

chrome content of the steels tested

16 M

nCr

5

20 M

nCr

5

18 C

rNi 8

17 C

rNi 6

-620 N

iMoC

r 6-

5

20 M

oCr

4

Har

dne

ss in

HV

0.5

Carbon Content in % by weight

Direct hardening925 °C/oil

direct hardening

900

800

700

600

500

400

300

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3

20 MoCr 420 NiMoCr 6-518 CrNi 816 MnCr 5

Fig. 3: Residual austenite content as afunction of chrome content and carburis-ing temperature

Fig. 4: Hardness as a function ofthe carbon content of the surface

layer after direct hardening

34

with their precise, specific control

of the carbon potential and the

carburising cycle, mean that

practically all case-hardening

steels can be direct-hardened,

regardless of their alloy content.

Fig. 5 shows the different carbon

contents at the surface that have

to be chosen for various case-

hardening steels in order to en-

sure maximum surface hardness.

The proportions of residual aus-

tenite are appreciably lower after

single hardening since, on hard-

ening from lower temperatures

adjusted to the carbon content at

the surface, any excess carbon

Fig. 5: Carbon content in the surfacelayer targeted during direct hardeningto obtain maximum possible hardnessas a function of the chrome content

remains bound in the form of car-

bide (Fig. 10 and 11).

Fatigue strength

In addition to higher wear resis-

tance, case-hardened steels

should also exhibit high strength

under dynamic stressing. On

hardening a cross-section with a

carburised surface layer, the

lower-carbon core undergoes

transformation before the high-

carbon surface layer due to the

higher martensite temperature.

Since the martensite transforma-

tion is accompanied by an in-

crease in volume, high internal

compression stresses develop

that are balanced by internal ten-

sile stresses. The compression

stresses in the surface layer

counteract the external, usually

tensile, stresses and thus in-

crease the fatigue strength.

The fatigue strength of case-

hardened components also

depends on the ratio of the car-

burised surface layer to the non-

carburised section. With bending

and torsional stresses, the fatigue

strength increases with increasing

case depth and core strength. In

the unusual case of tensile/com-

pression stressing, the signifi-

cance of the core strength in-

creases. The alloying elements

affect fatigue strength through the

hardenability in the core and the

surface layer and also through the

residual austenite content.

Chrome content in % by weight

Car

bon

con

tent

in t

he s

urfa

ce la

yer

in %

by

wei

ght

0.9

0.8

0.7

0.6

0.50.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1

20 M

oCr

4

16 M

nCr

5

20 M

nCr

5

17 C

rNi 6

-6

18 C

rNi 8

35


Austenite grain size

Fine-grain stability in case-

hardening steels is particularly

important at the high tempera-

tures reached during direct hard-

ening, due to the fact that grain

growth with coarse or mixed grain

can lead to the danger of distor-

tion and reduced toughness. By

selectively balancing the quanti-

ties of aluminium and nitrogen,

the inhibiting effect of aluminium

nitride precipitations on grain

growth can be used to achieve a

largely stable fine-grain structure.

According to DIN 17 210, fine

grain structure is assured after

treatment at 930 +/- 10 °C/4 h/

water. Prior hot forming and heat

treatments can have a significant

effect on the stability of the fine

grain. In disputed cases, anneal-

ing treatment at 1150 °C/30 min/

air is recommended as pre-

treatment, in order to produce a

uniform initial state.

Toughness of the surface

layer under impact loading

Case-hardened components must

remain ductile under high dynam-

ic stressing in order to avoid

brittle factures. Since the high-

carbon martensite in the surface

layer exhibits only low toughness,

the toughness of the component

is determined largely by the

depth of the carburised surface

layer and the toughness of the

core material. The impact tough-

ness of the component dimin-

ishes with increasing case depth.

For reasons connected with the

fatigue strength, however, the

case depth should not be too

small. The toughnesss of the sur-

face layer can be improved by

choosing a nickel content > 1.5%.

To date, no standard test for the

characterisation of the impact

toughness of case-hardened

steels has been accepted. One

frequently used method is the

Brugger test, with which the

maximum impact strength of a

case-hardened notched impact

specimen is measured.

36

37

Machining and heat treatment


Chipless forming

Case-hardening steels are well

suited to hot forming. Due to the

low carbon content, they possess

good cold-working properties

that, however, deteriorate with

increasing carbon and alloy con-

tents. Depending on the chemical

composition, the choice of a suit-

able structure (AC, FP) can im-

prove cold-forming properties.

Chip machining

Chip machining of case-harden-

ing steels is affected by the struc-

tural state, the strength and non-

metallic inclusions (sulphides,

oxides).

Ferritic-pearlitic structures, such

as can be achieved with un-

alloyed or low-alloy case-harden-

ing steels like Ck 15 and 17 Cr 3

by controlled cooling from the

forming temperature, are espe-

cially well suited for chip machin-

ing. Special heat treatment (FP

annealing) is required for higher-

alloyed steels. At very low hard-

ness values, case-hardening

steels tend to “smear” and form

built-up edges. In such cases,

heat treatment to a particular

strength (“TH”) is of advantage.

With high-alloy nickel-chrome or

nickel-chrome-molybdenum case-

hardening steels, the transition to

the ferrite-pearlite stage is often

incomplete, leaving traces of

bainite and a banded structure

that reduce machinability. These

steels are therefore also ma-

chined in the AC-annealed condi-

tion.

Case-hardening steels are fre-

quently produced with a con-

trolled sulphur content of 0.020 -

0.035%. Machinability is then

improved by an increase in sul-

phide inclusions. Deliberate con-

trol of the oxide inclusions

(calcium treatment) also

allows the machinability of

case-hardening steels to

be changed for the better.

Heat treatments for as-

supplied conditions

Depending on the product con-

cerned and the anticipated pro-

cessing, case-hardening steels

can be supplied in various treated

conditions. The most important

heat treatments are described

below. Table 1 provides an over-

view of the Brinell hardness

values that should be chosen for

these conditions.

Treatment for shearing S

(Fig. 6, Curve 1)

Appropriate cooling and/or

annealing to achieve a maximum

hardness of 255 HB.

Time

Tem

per

atur

e Soft annealing, A

annealing to spherical, AC

Treating forshearing, S

2

3

4

1

AC3

AC1

Fig. 6: Schematic representation of the temperature/time profile when

treating for shearing (S), soft-annealing (A) andannealing to spherical carbides (AC)

Code name Material No. S

(treated for

shearing)

HB max.

A

(soft-annealed)

HB max.

TH1)

(treated for

strength)

HB

FP2)

(treated for ferrite-

pearlite structure)

HB

AC

(annealed to

spherical carbides)

HB max.

Soft annealing A

(Fig. 6, Curve 2)

Heat treatment for reducing the

hardness of a workpiece to

values below a certain prescribed

value.

38

Table 1: Brinell hardness in various treatment conditions 1) For diameters up to 150 mm2) For diameters up to 60 mm3) Can be sheared in as-rolled condition

Hardnesses in treated condition1)Steel grade

C 15 E 1.1141 – 143 – – 135

C 15 R 1.1140 – 143 – – 135

17 Cr 3 1.7016 – 174 – – 155

16 MnCr 5 1.7131 – 207 156 to 207 140 to 187 165

16 MnCrS 5 1.7139 – 207 156 to 207 140 to 187 165

20 MnCr 5 1.7147 255 217 170 to 217 152 to 201 180

20 MnCrS 5 1.7149 255 217 170 to 217 152 to 201 180

20 MoCr 4 1.7321 255 207 156 to 207 140 to 187 165

20 MoCrS 4 1.7323 255 207 156 to 207 140 to 187 165

22 CrMoS 3-5 1.7333 255 217 170 to 217 152 to 201 180

20 NiCrMo 2-2 1.6523 2553) 212 161 to 212 148 to 194 176

20 NiCrMoS 2-2 1.6526 2553) 212 161 to 212 148 to 194 176

20 NiMoCrS 6-5 1.6757 255 220 170 to 220 155 to 205 180

17 CrNi 6-6 1.5918 255 229 175 to 229 156 to 207 178

18 CrNi 8 1.5920 255 225 179 to 229 158 to 205 180

18 CrNiMo 7-6 1.6587 255 229 179 to 229 159 to 207 180

15 NiCr 13 1.5752 255 229 179 to 229 166 to 217 180

Treating for strength (TH)

(Fig. 7, Curve 1)

Heat treatment with appropriate

cooling and subsequent temper-

ing in order to achieve a certain

range of hardness.

Treating for ferrite-pearlite

structure (FP)

(Fig. 8, Curve 1)

(also called “pearlitising, isother-

mal annealing”) Isothermal trans-

formation, consisting of austenit-

ising, subsequent cooling to a

temperature in the pearlite

stage and holding, so that

the austenite is trans-

formed completely into

ferrite-pearlite. Fig. 9

shows the shortest trans-

formation times at ideal

transformation temperatures in

the pearlite stage for the most

common case-hardening steels.

The transformation time depends

on the temperature cycle, the size

of the workpiece and the state of

nucleation of the austenite after

forging. Considerably longer

transformation times are neces-

sary at other transition tempera-

tures in the pearlite stage.

Annealing to spherical

carbides AC (Fig. 6, Curves 3, 4)

Annealing with the aim of spher-

oidising the carbides. This gener-

ally comprises holding for a

lengthy period of time at a tempe-

rature near AC1, oscillating about

this temperature, if necessary.

39


t t

range of bainite structure

Martensite range

TTT-Diagram (continous)

Start of transformation

End of transformation

Austenite range

Ferrite range

Pearlite range

Tem

per

atur

e

1000

900

800

700

600

500

400

300

200

100

0Time (log.) Time in h

A

M

1

B

2F P

1

3

=

=

A

F

P

B

M

AC1

AC3

AC1

MS

AC3

1

Fig. 7: Schematic representation of the temperature/time profile forTH annealing ➀ , hardening ➁ und tempering ➂

1000

900

800

700

600

500

400

300

200

100

0

AF

P

B

1

=

=

A

F

P

M

MS

AC3

AC1

B

M

Austenite range

Ferrite range

Pearlite range

TTT-Diagram (isothermal)

Tem

per

atur

e in

o C

Start of transformation

End of transformation

range of bainite structure

Martensite range

Time (log.) t

Tem

per

atur

e in

°C

Pearlitising time in minutes

tra

nsiti

on t

emp

erat

ure

in °

C 650

660

650

660

650

640

640

640

20 NiMoCr 6-5

18 CrNiMo 7-6

18 CrNi 8

20 MoCr 4

17 CrNi 6-6

20 NiMoCr 2-2

20 MnCr 5

16 MnCr 5

0 20 40 60 80 100 120

Fig. 9: Time ranges for completetransformation to pearlite for various case-hardening steels (austenitising temperaturerange 870-900 °C)* Acc. to P. G. Dressel and H. Gulden

Fig. 8: Schematic representationof the temperature/time profile

for pearlitising (FP)

40

Case hardening consists of the

following stages:

1. Carburising of the surface

layer to certain case depths

and certain carbon contents in

the layer.

2. Subsequent hardening.

3. Tempering (stress-relieving).

For the carburising and hardening

stages, there are various proven

processing cycles that are

chosen on the basis of technical

and economic aspects.

Carburising

Carburising means the thermo-

chemical treatment of a work-

piece in the austenitic condition

with the aim of enriching the sur-

face layer with carbon. After this

treatment, the carbon is usually in

the austenite in solid solution.

Carburising takes place in a

medium which releases carbon.

The carburising medium can be a

solid (powder), liquid or gas.

A distinction is therefore made

between:

Powder carburising,

Salt bath carburising,

Gas carburising.

The quantity of carbon introduced

into the surface layer is primarily

dependent on the carburising

effect of the medium. The case

depth depends mainly on the

temperature and duration of the

treatment. Since the rate of diffu-

sion increases with rising tempe-

ratures, the time required to reach

the desired case depth is reduced

at higher temperatures. Similarly,

the gradient of the carbon con-

tent from the surface to the core

becomes flatter.

In order for the surface hardness to

be high enough and, at the same

time, for residual austenite and

secondary cementite to be elimi-

nated as far as possible, it is nec-

essary to aim for a carbon content

at the surface which is below that

of the eutectic composition.

In line with their carbon content,

the surface and core of the work-

Case-hardening treatment

piece exhibit different AC3 and MS

temperatures and also different

transformation behaviour.

The most favourable hardening

temperatures for the core are

approx. 100 °C above those for

the surface layer (see Material

Data Sheets, Page 22 ff.). In prac-

tice, this behaviour leads to

various treatment cycles.

Hardening

(Fig.7, Curve 2)

Hardening is taken to mean heat

treatment consisting of austenitis-

ing and cooling, under conditions

leading to an increase in hard-

ness due to more or less com-

plete transformation of the aus-

tenite into martensite and possi-

bly bainite.

41


Quenching after carburising is

preferably carried out in oil. For

workpieces of complicated de-

sign, hot bath hardening at ap-

proximately 160 - 250 °C, fol-

lowed by cooling in air, is advis-

able. For coarser workpieces of

simple design, quenching in water

can be chosen. In order to trans-

form larger proportions of residu-

al austenite into martensite after

hardening, final subzero cooling

to -180 °C can be carried out, e.g.

on CrNi and CrNiMo steels.

Direct hardening (Fig. 10)

Direct hardening means quench-

ing immediately after carburising

treatment that has been carried

out in the austenite temperature

range.

During the direct hardening of

case-hardening steels, quenching

is carried out immediately after

carburising, either directly from

the case temperature or after a

short pause (V in Fig. 10). This

method is mainly used in connec-

tion with gas carburising in the

mass production of gearing com-

ponents.

The time required for the case-

hardening of steels can be con-

siderably reduced by ensuring a

high carbon potential during the

actual carburising phase and the

subsequent diffusion period,

and/or by using high tempera-

tures. Since higher carburising

temperatures have a negative

effect on attempts to minimise

distortion when quenching, it is

expedient to let the temperature

drop somewhat after carburising

and then quench from a lower

temperature that is still sufficient

for hardening (denoted V). This is

especially true for parts with a

complex design. Distortion can

be minimised in this way.

Single hardening

Single hardening means a single

hardening process carried out

after prior carburising and cooling

to ambient temperature. If car-

burising is followed by isothermal

transformation, this is referred to

as single hardening with isother-

mal transformation.

In the case of single hardening,

the carburised parts are first

cooled slowly in the carburising

vessel and then hardened in the

usual way, possibly after interme-

diate treatment. The hardening

temperatures used usually lie just

above the AC3 point of the surface

layer. It is, however, also possible

to choose hardening tempera-

tures that are just above or below

the AC3 point of the core.

Hardening (oil)

Tem

per

atur

e

Carburisation (gas or salt bath)

Tempering

TimeDirect Hardening 10

(core)(surface)

Direkthärten

VAc3

Ac3

Fig. 10: Direct hardening

42

Single hardening after cool-

ing from the case (Fig. 11)

When hardening from tempera-

tures just slightly above the AC3

value for the surface, only partial

transformation occurs in the core

because the hardening tempera-

ture is then under the AC3 value

for the core. The core then re-

mains soft and can have a coarse

structure as a result of the long

holding time at the high carburis-

ing temperature. In the case layer,

on the other hand, a hard, fine-

grain, homogeneous structure

develops that provides good wear

and fatigue strength properties. If

cementite has formed, precipi-

tated out at the grain boundaries

as a lattice pattern, the low hard-

ening temperature is not sufficient

to dissolve the cementite lattice.

The advantages of this method of

hardening lie in the fact that the

non-carburised area remains

machinable, even after quench-

ing, and that distortion remains

negligible due to the low harden-

ing temperature.

The disadvantage is that

low toughness in the core

must be expected.

When hardening from tem-

peratures that are above the AC3

temperature of the core (C in Fig.

11), the core undergoes complete

transformation, becomes fine-

grained and thus gains in strength

and toughness. Although the

grain of the surface layer then

becomes somewhat coars-

er, any cementite lattice is

dissolved and surface em-

brittlement eliminated.

Since, on hardening from

high temperatures, the amount of

residual austenite in the carbu-

rised surface layer increases with

increasing carbon content, espe-

cially with alloyed case-hardening

steels, it is advisable to aim for a

lower carbon content in the sur-

face layer. Traces of residual aus-

tenite should favour smooth run-

ning of gear wheels, for example,

and also facilitate running-in.

Quite apart from that, a surface

layer absolutely free of residual

austenite is, for many alloyed

case-hardening steels, virtually

impossible without the use of

special methods (e.g. low-

temperature treatments)

Single hardening after inter-

mediate annealing (Fig. 12)

In certain cases, for example the

elimination of distortion caused

by carburising and cooling, it can

be expedient to introduce an

intermediate processing stage

before hardening. To this end, the

parts are subjected to interme-

diate annealing below the AC1

temperature.

Carburisation

Time

Tem

per

atur

e

Cooling(case or air)

Hardening (oil)

Tempering

(core)(surface)

CAc3

Ac3

Fig. 11: Single hardening after coolingfrom the case

Carburisation

Tem

per

atur

e Hardening(oil)

Cooling(case or air)


Time

Tempering

(core)(surface)(core)

CAc3

Ac3

Ac1

Fig. 12 Single hardening after intermediate annealing

43


Single hardening after iso-

thermal transformation

(Fig. 13)

This method of treatment is suit-

able for high-alloy case-hardening

steels (e.g. 18 CrNi 8) that show a

tendency to stress corrosion

cracking after cooling in air from

the case, due to differences in the

transformation rates between the

surface and the core.

Double hardening (Fig. 14)

Double hardening means two

stages of hardening, in which

quenching is generally carried out

from different temperatures.

With carburised workpieces, the

first hardening process can be

direct hardening, while the

second is carried out from

a lower temperature.

Double hardening is usual-

ly used when tough surface layers

and core zones are required,

together with greater case depth.

Double hardening is generally

carried out first from the AC3

temperature of the core and then

from the AC3 temperature of the

surface area. The tendency to

distortion is greatest with double

hardening.

Tempering

(Fig. 7, Curve 3)

Tempering means the single or

repeated heating of a hardened

workpiece to a prescribed tem-

perature (< AC1), holding at this

temperature and subsequent

appropriate cooling.

After hardening, it is advisable to

temper the workpieces at 150 -

180 °C for unalloyed steels and at

170 - 210 °C for alloyed steels.

Martensite tempered in this way

has less of a tendency to form

grinding cracks. The hardness in

the surface layer drops only

slightly (approx. 1 - 2 HRC).

Carburisation

Tem

per

atur

e Hardening (oil)

Salt bathIsothermal transformation

13Single hardening after isothermal transformation

Time

Tempering

(core)(surface)

Pearlite stage(core)

t

CAc3

Ac3

Fig. 13: Single hardening after isothermaltransformation

Carburisation

Tem

per

atur

e

Hardening (oil)

Double hardening4Time

Tempering

(core)(surface)

Hardening(oil)

Ac3

Ac3

Fig. 14: Double hardening

44

Overview of gradesand chemical composition

Table 2 contains an overview of

the most common case-hardening

steels that, with the exception of

the 18 CrNi 8 and 20 NiMoCr 6-5

steels, are included in standard

DIN EN 10 084, together with the

chemical composition of the

case-hardening steels.

Table 2: Overview of grades and chemical composition of the steels

Chemical compositionMain alloy contents in % (typical values)

Carbodur Code name C Si Mn P max. S Cr Ni Mo

Carbodur C 15 E C 15 E 0.12-0.18 ≤0.40 0.30-0.60 0.035 ≤0.035 – – –

Carbodur C15 R C15 R 0.12-0.18 ≤0.40 0.30-0.60 0.035 0.020-0.040 – – –

Carbodur 17 Cr 3 17 Cr 3 0.14-0.20 ≤0.40 0.60-0.90 0.035 ≤0.035 0.70-1.00 – –

Carbodur 16 MnCr 5 16 MnCr 5 0.14-0.19 ≤0.40 1.00-1.30 0.035 ≤0.035 0.80-1.10 – –

Carbodur 16 MnCrS 5 16 MnCrS 5 0.14-0.19 ≤0.40 1.00-1.30 0.035 0.020-0.040 0.80-1.10 – –

Carbodur 20 MnCr 5 20 MnCr 5 0.17-0.22 ≤0.40 1.10-1.40 0.035 ≤0.035 1.00-1.30 – –

Carbodur 20 MnCrS 5 20 MnCrS 5 0.17-0.22 ≤0.40 1.10-1.40 0.035 0.020-0.040 1.00-1.30 – –

Carbodur 20 MoCr 4 20 MoCr 4 0.17-0.23 ≤0.40 0.70-1.00 0.035 ≤0.035 0.30-0.60 – 0.40-0.50

Carbodur 20 MoCrS 4 20 MoCrS 4 0.17-0.23 ≤0.40 0.70-1.00 0.035 0.020-0.040 0.30-0.60 – 0.40-0.50

Carbodur 22 CrMoS 3-5 22 CrMoS 3-5 0.19-0.24 ≤0.40 0.70-1.00 0.035 0.020-0.040 0.70-1.00 – 0.40-0.50

Carbodur 20 NiCrMo 2-2 20 NiCrMo 2-2 0.17-0.23 ≤0.40 0.65-0.95 0.035 ≤0.035 0.35-0.70 0.40-0.70 0.15-0.25

Carbodur 20 NiCrMoS 2-2 20 NiCrMoS 2-2 0.17-0.23 ≤0.40 0.65-0.95 0.035 0.020-0.040 0.35-0.70 0.40-0.70 0.15-0.25

Carbodur 20 NiMoCrS 6-5 20 NiMoCrS 6-5 0.17-0.23 0.15-0.40 0.60-0.90 0.035 0.020-0.035 0.30-0.50 1.40-1.80 0.40-0.50

Carbodur 17 CrNi 6-6 17 CrNi 6-6 0.14-0.20 ≤0.40 0.50-0.90 0.035 ≤0.035 1.40-1.70 1.40-1.70 –

Carbodur 18 CrNi 8 18 CrNi8 0.15-0.20 0.15-0.40 0.40-0.60 0.035 ≤0.035 1.80-2.10 1.80-2.10 –

Carbodur 18 CrNiMo 7-6 18 CrNiMo 7-6 0.15-0.21 ≤0.40 0.50-0.90 0.035 ≤0.035 1.50-1.80 1.40-1.70 0.25-0.35

Carbodur 15 NiCr 13 15 NiCr 13 0.14-0.20 ≤0.40 0.40-0.70 0.035 ≤0.035 0.60-0.90 3,00-3,50 –

Overview of grades

Material No.

1.1141

1.1140

1.7016

1.7131

1.7139

1.7147

1.7149

1.7321

1.7323

1.7333

1.6523

1.6526

1.6757

1.5918

1.5920

1.6587

1.5752

45


C ≤0.31 ±0.02

Si ≤0.40 +0.03

Mn ≤1.00 ±0.04

>1.00≤1.40 ±0.05

P ≤0.035 ±0.005

S ≤0.040 +0.0052)

Cr ≤1.80 ±0.05

Mo ≤0.30 ±0.03

>0.30≤0.50 ±0.04

Ni ≤2.00 ±0.03

>2.00≤3.50 ±0.07

Element Maximum

permissible content

in the melt analysis

Permissible deviations of the check analysis1)

from the limits

for the melt analysis to DIN EN 10084

1) ± means that, for a given melt, either the upper or the lower limit of the range given for the melt analysis in Table 2 may be exceeded, but not bothat once.

2) For steels with a range of 0.020 bis 0.040% sulphur according to the meltanalysis, the deviation from the limitis ±0.005%.

Carbodur Material No. Code name

to DIN EN 10084

Standardised in USA

SAE/ASTM

Japan

JIS

Permissible deviations between check analysis and melt analysis

Comparison of international standards

Carbodur C 15 E 1.1141 C 15 E DIN EN 10084 1015 S 15

Carbodur C 15 R 1.1140 C 15 R DIN EN 10084 – –

Carbodur 17 Cr 3 1.7016 17 Cr 3 DIN EN 10084 – –

Carbodur 16 MnCr 5 1.7131 16 MnCr 5 DIN EN 10084 5115 –

Carbodur 16 MnCrS 5 1.7139 16 MnCrS 5 DIN EN 10084 – –

Carbodur 20 MnCr 5 1.7147 20 MnCr 5 DIN EN 10084 5120 SMnC 420 H

Carbodur 20 MnCrS 5 1.7149 20 MnCrS 5 DIN EN 10084 – –

Carbodur 20 MoCr 4 1.7321 20 MoCr 4 DIN EN 10084 – –

Carbodur 20 MoCrS 4 1.7323 20 MoCrS 4 DIN EN 10084 – –

Carbodur 22 CrMoS 3-5 1.7333 22 CrMoS 3-5 DIN EN 10084 – –

Carbodur 20 NiCrMo 2-2 1.6523 20 NiCrMo 2-2 DIN EN 10084 8620 SNCM 220 (H)

Carbodur 20 NiCrMoS 2-2 1.6526 20 NiCrMoS 2-2 DIN EN 10084 – –

Carbodur 20 NiCrMoS 6-5 1.6757 20 NiCrMoS 6-5 – – –

Carbodur 17 CrNi 6-6 1.5918 17 CrNi 6-6 DIN EN 10084 – –

Carbodur 18 CrNi 8 1.5920 18 CrNi 8 – – –

Carbodur 18 CrNiMo 7-6 1.6587 18 CrNiMo 7-6 DIN EN 10084 – –

Carbodur 15 NiCr 13 1.5752 15 NiCr 13 DIN EN 10084 3310 / 3415 / 9314 SNC 815 (H)

46

Forms supplied

55 – 250 mm dia.

Sharp-edged50 – 103 mm square

DIN 1014

DIN 7527

DIN 1013

> 200 mm dia. standard in-company tolerance, closertolerance on request

Subject topurchaseorder

Special:*)≤ +100/-0

Flat:Width: 80 – 510 mmThickness: 25 – 160 mmWidth/thickness ratio 10:1 max

Width: 25 – 160 mm

Thickness:80 – 550 mm

65 – 750 mm dia.

265 – 650 mm square

flat: on request

50 – 320 mm square,rising in 1 mm incre-ments

52 – 400 mm dia.

52 – 300 mm dia.

DIN 1017up to 150 mm width and 60 mm thickness;over 150 mm widthstandard in-company tole-rance

Tolerance on request

< 210 mm +/- 2%> 210 mm +/- 3%of edge length

Special:*)≤ 100 mm +/- 1%

of edge length

> 100 mm – 210 mm

+/- 1.5% of edge length

ISA Tol. 11 or comparabletolerance

ISA Tol. 11 or comparabletolerance

ISA-Tol. 8 or comparable tolerance

≤ 80 mm: 4.0 mm/m

> 80 mm: 2.5 mm/m

4.0 – 10 m,other lengthson request

Lengths as a function ofdimensionsand heat-treatmentcondition on request

3 - 10 m, onrequest 30 mmax. as afunction ofdia. andmax. bardead weightof 7 t

Hot-sawn or hot abrasi-ve-cut

Special:*)Cold-sawn,cold abrasive-cut

Hot abrasive-cut or cold-sawn

Special:*)Cold abrasive-cut

≤ 210 mm square:hot-sawn or hot abrasi-ve-cut

> 210 mm square:hot-sheared

Special:*)Cold abrasive-cut, cold-sawn

Hot-sawn/hotabrasive-cut

Special:*)Cold-sawn/abrasive-cut

Dimensions 50- 105 mm withround chamfer30° or 45°,chamfer widthapprox. 5 -12mm, otherwidths by ar-rangement

Rough-peeled finishavailable for 52 -240 mm

Max. permissiblesurface defect dep-ths:

Round: 1% max. ofdia. + 0.05 mm

Square: 1% max. ofedge length

Flat: 1.5% max. ofwidth, 2.0% max. ofthickness

Special:*)Smaller surfacedefect depth onrequest

Special:*)

- Rough-peeled- Turned- Milled

Edge radius:

< 210 mm - 12-18%of edge length

> 210 mm: withoutdefined edge radius

Max. perm. surfacedefect depth:

≤ 140 mm sq.0.3 mm max.

> 140 - 200 mm sq.0.6 mm max.

> 200 mm sq.visible defects elimi-nated

Technically crack-freecondition e.g. eddy-current tested orcomparable tech-nique, defined depthof roughness and sui-table packaging byspecial arrangement

< 1000 mm2:4.0 mm/m

> 1000 mm2:2.5 mm/m

Special:*)Speciallystraightened

Standard: 6 mm/m

Special:*)4 mm/m

As-peeledstraightness ≤ 2 mm/m, 1 mm/m orcloser as afunction ofdimensions on request

Untreated

Cold-sheara-ble

Cold-sawable

Normalized

Treated toferrite-pearlitestructure

Treated tohardnessrange

Soft-annealed

Spheroidize-annealed

Stress-relie-ved

Quenchedand tempered

Bar steeland roundbillets fortubemakingrolled

Sheet barsrolled withbulbous nar-row face

Bar steeland semis forged

Semisrolled

Bright steel

peeled

peeled andpolished

*) Special finishes subject to further inquiry (partly dependent on quality, dimensions and condition)

ground 52 – 100 mm dia.

Semis:as-forgedstraightness

Bar steel:to DIN withinthe tolerancelimit

3 – 8 m

Surface finishAs-suppliedcondition

End condition

Lengths/weightsStraightnessLengthsDia. or edge length

TolerancesProduct Dimensions

on requestAs-castingots/c.c.blooms Open-dieforgings

Forgings forged toshape on request(drawing)

47

Hardness comparison table

Tensile strength, Brinell, Vickers and Rockwell hardness

Tensilestrength

RmN/mm2

Ball inden-tation mm

d HB

Brinell hardness Vickershardness

HV

Rockwell hardness

HRB HRC HR 30 N

255 6.63 76.0 80 – – –270 6.45 80.7 85 41.0 – –285 6.30 85.5 90 48.0 – –305 6.16 90.2 95 52.0 – –320 6.01 95.0 100 56.2 – –335 5.90 99.8 105 – – –350 5.75 105 110 62.3 – –370 5.65 109 115 – – –385 5.54 114 120 66.7 – –400 5.43 119 125 – – –415 5.33 124 130 71.2 – –430 5.26 128 135 – – –450 5.16 133 140 75.0 – –465 5.08 138 145 – – –480 4.99 143 150 78.7 – –495 4.93 147 155 – – –510 4.85 152 160 81.7 – –530 4.79 156 165 – – –545 4.71 162 170 85.0 – –560 4.66 166 175 – – –575 4.59 171 180 87.1 – –595 4.53 176 185 – – –610 4.47 181 190 89.5 – –625 4.43 185 195 – – –640 4.37 190 200 91.5 – –660 4.32 195 205 92.5 – –675 4.27 199 210 93.5 – –690 4.22 204 215 94.0 – –705 4.18 209 220 95.0 – –720 4.13 214 225 96.0 – –740 4.08 219 230 96.7 – –755 4.05 223 235 – – –770 4.01 228 240 98.1 20.3 41.7785 3.97 233 245 – 21.3 42.5800 3.92 238 250 99.5 22.2 43.4820 3.89 242 255 – 23.1 44.2835 3.86 247 260 (101) 24.0 45.0850 3.82 252 265 – 24.8 45.7865 3.78 257 270 (102) 25.6 46.4880 3.75 261 275 – 26.4 47.2900 3.72 266 280 (104) 27.1 47.8915 3.69 271 285 – 27.8 48.4930 3.66 276 290 (105) 28.5 49.0950 3.63 280 295 – 29.2 49.7965 3.60 285 300 – 29.8 50.2995 3.54 295 310 – 31.0 51.3

1030 3.49 304 320 – 32.2 52.31060 3.43 314 330 – 33.3 53.61095 3.39 323 340 – 34.4 54.41125 3.34 333 350 – 35.5 55.41155 3.29 342 360 – 36.6 56.41190 3.25 352 370 – 37.7 57.41220 3.21 361 380 – 38.8 58.41255 3.17 371 390 – 39.8 59.31290 3.13 380 400 – 40.8 60.21320 3.09 390 410 – 41.8 61.11350 3.06 399 420 – 42.7 61.91385 3.02 409 430 – 43.6 62.71420 2.99 418 440 – 44.5 63.51455 2.95 428 450 – 45.3 64.31485 2.92 437 460 – 46.1 64.91520 2.89 447 470 – 46.9 65.71555 2.86 (456) 480 – 47.7 66.41595 2.83 (466) 490 – 48.4 67.11630 2.81 (475) 500 – 49.1 67.71665 2.78 (485) 510 – 49.8 68.31700 2.75 (494) 520 – 50.5 69.01740 2.73 (504) 530 – 51.1 69.51775 2.70 (513) 540 – 51.7 70.01810 2.68 (523) 550 – 52.3 70.51845 2.66 (532) 560 – 53.0 71.21880 2.63 (542) 570 – 53.6 71.71920 2.60 (551) 580 – 54.1 72.11955 2.59 (561) 590 – 54.7 72.71995 2.57 (570) 600 – 55.2 73.2

Tensilestrength

RmN/mm2

Ballindentation

mm d HB

Brinell hardness Vickershardness

HV

Rockwell hardness

HRB HRC HR 30 N

2030 2.54 (580) 610 – 55.7 73.72070 2.52 (589) 620 – 56.3 74.22105 2.51 (599) 630 – 56.8 74.62145 2.49 (608) 640 – 57.3 75.12180 2.47 (618) 650 – 57.8 75.5

– – – 660 – 58.3 75.9– – – 670 – 58.8 76.4– – – 680 – 59.2 76.8– – – 690 – 59.7 77.2– – – 700 – 60.1 77.6– – – 720 – 61.0 78.4– – – 740 – 61.8 79.1– – – 760 – 62.5 79.7– – – 780 – 63.3 80.4– – – 800 – 64.0 81.1– – – 820 – 64.7 81.7– – – 840 – 65.3 82.2– – – 860 – 65.9 82.7– – – 880 – 66.4 83.1– – – 900 – 67.0 83.6– – – 920 – 67.5 84.0– – – 940 – 68.0 84.4

Tensile strength N/mm2 Rm

Brinell hardness1) Diameter of the d1) Calculated from: ball indentation in mm

HB = 0.95 · HV

(0.102 F/D2 = 30) Hardness HBD = 10 value =

Vickers hardness Diamond pyramid HVTest forces ≥ 50 N

Rockwell hardness Ball 1.588 mm (1/16“) HRBTotal test force = 98 N

Diamond cone HRCTotal test force = 1471 N

Diamond coneTotal test force = 294 N HR 30 N

0.102 · 2 Fπ D (D – √D2 – d2)

Conversions of hardness values using this conversion table are only approximate.See DIN 50 150, December 1976.

Temperature Comparison

Chart

°C °F K °C °F K °C °F K

–273,15 –459,67 0,00 380,00 716,00 653,15 910,00 1670,00 1183,15

–270,00 –454,00 3,15 390,00 743,00 663,15 920,00 1688,00 1193,15

–200,00 –328,00 73,15 400,00 752,00 673,15 930,00 1706,00 1203,15

–150,00 –238,00 123,15 410,00 770,00 683,15 940,00 1724,00 1213,15

–100,00 –148,00 173,15 420,00 788,00 693,15 950,00 1742,00 1223,15

– 90,00 –130,00 183,15 430,00 806,00 703,15 960,00 1760,00 1233,15

– 80,00 –112,00 193,15 440,00 824,00 713,15 970,00 1778,00 1243,15

– 70,00 – 94,00 203,15 450,00 842,00 723,15 980,00 1796,00 1253,15

– 60,00 – 76,00 213,15 460,00 860,00 733,15 990,00 1814,00 1263,15

– 50,00 – 58,00 223,15 470,00 878,00 743,15 1000,00 1832,00 1273,15

– 40,00 – 40,00 233,15 480,00 896,00 753,15 1010,00 1850,00 1283,15

– 30,00 – 22,00 243,15 490,00 914,00 763,15 1020,00 1868,00 1393,15

– 20,00 – 4,00 253,15 500,00 932,00 773,15 1030,00 1886,00 1303,15

– 17,78 0,00 255,37 510,00 950,00 783,15 1040,00 1904,00 1313,15

– 10,00 14,00 263,15 520,00 968,00 793,15 1050,00 1922,00 1323,15

0,00 32,00 273,15 530,00 986,00 803,15 1060,00 1940,00 1333,15

10,00 50,00 283,15 540,00 1004,00 813,15 1070,00 1958,00 1343,15

20,00 68,00 293,15 550,00 1022,00 823,15 1080,00 1976,00 1353,15

30,00 86,00 303,15 560,00 1040,00 833,15 1090,00 1994,00 1363,15

40,00 104,00 313,15 570,00 1058,00 843,15 1100,00 2012,00 1373,15

50,00 122,00 323,15 580,00 1076,00 853,15 1110,00 2030,00 1383,15

60,00 140,00 333,15 590,00 1094,00 863,15 1120,00 2048,00 1393,15

70,00 158,00 343,15 600,00 1112,00 873,15 1130,00 2066,00 1403,15

80,00 176,00 353,15 610,00 1130,00 883,15 1140,00 2084,00 1413,15

90,00 194,00 363,15 620,00 1148,00 893,15 1150,00 2102,00 1423,15

100,00 212,00 373,15 630,00 1166,00 903,15 1160,00 2120,00 1433,15

110,00 230,00 383,15 640,00 1184,00 913,15 1170,00 2138,00 1443,15

120,00 248,00 393,15 650,00 1202,00 923,15 1180,00 2156,00 1453,15

130,00 266,00 403,15 660,00 1220,00 933,15 1190,00 2174,00 1463,15

140,00 284,00 413,15 670,00 1238,00 943,15 1200,00 2192,00 1473,15

150,00 302,00 423,15 680,00 1256,00 953,15 1210,00 2210,00 1483,15

160,00 320,00 433,15 690,00 1274,00 963,15 1220,00 2228,00 1493,15

170,00 338,00 443,15 700,00 1292,00 973,15 1230,00 2246,00 1503,15

180,00 356,00 453,15 710,00 1310,00 983,15 1240,00 2264,00 1513,15

190,00 374,00 463,15 720,00 1328,00 993,15 1250,00 2282,00 1523,15

200,00 392,00 473,15 730,00 1346,00 1003,15 1260,00 2300,00 1533,15

210,00 410,00 483,15 740,00 1364,00 1013,15 1270,00 2318,00 1543,15

220,00 428,00 493,15 750,00 1382,00 1023,15 1280,00 2336,00 1553,15

230,00 446,00 503,15 760,00 1400,00 1033,15 1290,00 2354,00 1563,15

240,00 464,00 513,15 770,00 1418,00 1043,15 1300,00 2372,00 1573,15

250,00 482,00 523,15 780,00 1436,00 1053,15 1310,00 2390,00 1583,15

260,00 500,00 533,15 790,00 1454,00 1063,15 1320,00 2408,00 1593,15

270,00 518,00 543,15 800,00 1472,00 1073,15 1330,00 2426,00 1603,15

280,00 536,00 553,15 810,00 1490,00 1083,15 1340,00 2444,00 1613,15

290,00 554,00 563,15 820,00 1508,00 1093,15 1350,00 2462,00 1623,15

300,00 572,00 573,15 830,00 1526,00 1103,15 1360,00 2480,00 1633,15

310,00 590,00 583,15 840,00 1544,00 1113,15 1370,00 2498,00 1643,15

320,00 608,00 593,15 850,00 1562,00 1123,15 1380,00 2516,00 1653,15

330,00 626,00 603,15 860,00 1580,00 1133,15 1390,00 2234,00 1663,15

340,00 644,00 613,15 870,00 1598,00 1143,15 1400,00 2552,00 1673,15

350,00 662,00 623,15 880,00 1616,00 1153,15 1500,00 2732,00 1783,15

360,00 680,00 633,15 890,00 1634,00 1163,15 2000,00 3632,00 2273,15

370,00 698,00 643,15 900,00 1652,00 1173,15 2500,00 4532,00 2773,15

°C °F K

X = particular K X– 273 9/5 (X–273) + 32 X

measured °C X 9/5 X + 32 X + 273

temperature °F 5/9 (X–32) X 5/9 (X–32) + 273

48

50

Page Source Object/Motif

Cover Bavaria Gear wheel03 Lohmann + Stolterfoth Planetary gear04 Steinmetz Team meeting4 – 5 Sauter, Bachmann Spiral bevel gears4 Sauter, Bachmann Set of gears5 Sauter, Bachmann Precision worm

Company photo Micrograph6 – 7 ATA-GEARS Hardening of a ring gear7 Company photo Steel bars7 Steinmetz Chips8 CarboTech Cutting drum

Bavaria Hydroelectric power station8 – 9 Lohmann + Stolterfoth Planetary gear8 ATA-GEARS Spiral bevel gears9 Image Drilling rig

Bavaria Wind turbine generatorsSchreiber/Flender Gears for wind turbine generatorFrese Gear wheel

10 Schuster AirbusBavaria Formula 1 racecar

10 – 11 ATA-GEARS Ring gear with pinion10 Company photo/Flender Set of gears

11 DAF XF95 truck VW VW GolfImagine Oil tankerMAAG Gear Marine gearCompany photo Cable car

12 Company photo Printing pressLohmann + Stolterfoth Parabolic reflector

12 – 13 Company photo/Flender Set of gears12 Lohmann + Stolterfoth Gear wheels for combing cylinder gear13 Company photo Crane truck

Company photo Wheel loaderImagine Ariane rocketCompany photo/Flender Gear detail

14 Steinmetz Sawing of disksSteinmetz Disks with and without drilled holeSteinmetz Steel bars

15 Lohmann + Stolterfoth Ground gear wheels16 Company photo Electric arc furnace17 Company photo Continuous casting plant

Company photo ESR plant18 Company photo Forged steel bars

Company photo Peeling of steel bars18 – 19 Company photo Forging of steel bars

Company photo Sawing of steel barsSteinmetz Disks with drilled hole

36 Sauter, Bachmann Spiral bevel gears40 Lohmann + Stolterfoth Case hardening of a large wheel42 Lohmann + Stolterfoth Ground gear wheels

ATA-GEARS Spiral bevel gears43 Frese Gear wheel44 Lohmann + Stolterfoth Gear wheels for combing cylinder gear48 – 49 Lohmann + Stolterfoth Planetary gear

Photos

51

General note (liability)

All statements regarding the properties

or utilisation of the materials or products

mentioned are for the purposes of

description only. Guarantees regarding

the existence of certain properties or a

certain utilisation are only ever valid if

agreed upon in writing.

CARBODURCARBODUR

CARBODUR

EDELSTAHL WITTEN-KREFELD GMBHAuestrasse 4, D-58452 Witten · Tel. (+49) 23 02 / 29 43 07 · Telefax (+49) 2302 / 29 43 08

E-mail: [email protected] · Internet: www.edelstahl-witten-krefeld.de

• Sales - Case-hardening steelsTel. (+49) 23 02/29 43 46 · Telefax (+49) 23 02/29 46 87E-mail: [email protected]

• Quality DepartmentTel. (+49) 23 02/29 40 20 · Telefax (+49) 23 02/29 44 36Tel. (+49) 21 51/83 20 46 · Telefax (+49) 21 51/83 41 56

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