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Labelling system for grades of stainless steels and their strength classes

Stainless steels divide into three groups of steel - austenitic, ferritic and martensitic. Austenitic steel is by far the commonest and offers the greatest scope for use. The steel groups and strength classes are designated by a four-digit sequence of letters and numbers as shown in the following example. DIN EN ISO 3506 governs screws and nuts made from stainless steel.

 Example:

 A2 - 80
A = austenitic steel
2  = type of alloy within group A
80                    = tensile strength of at least 800 N/mm2, cold work hardened

Fig. A:


Tab. 10: Common stainless steels and their chemical composition

 

 

Material designation

 

Material no.

 

C

%

 

Si

%

 

Mn

%

 

Cr

%

 

Mo

%

 

Ni

%

 

Altri

%

 

 

 

 

 

A 2

 

X 5Cr Ni 1810

 

1.4301

 

0.07

 

1.0

 

2.0

17.5

to 19.5

 

-

8.0

to 10.5

 

-

 

X 2 Cr Ni 1811

 

1.4306

 

0.03

 

1.0

 

2.0

18.0

to 20.0

 

-

10

to 12.0

 

-

 

X 8 Cr Ni 19/10

 

1.4303

 

0.07

 

1.0

 

2.0

17.0

to 19.0

 

-

11.0

to 13.0

 

-

 

A 3

 

X 6 Cr Ni Ti 1811

 

1.4541

 

0.10

 

1.0

 

2.0

17.0

to 19.0

 

-

9.0

to 12.0

 

Ti ≥ 5 X

% C

 

 

 

A 4

 

X 5 Cr Ni Mo 1712

 

1.4401

 

0.07

 

1.0

 

2.0

16.5

to 18.5

2.0

to 2.5

10.0

to 13.0

 

-

 

X 2 Cr Ni Mo 1712

 

1.4404

 

0.03

 

1.0

 

2.0

16.5

to 18.5

2.0

to 2.5

10

to 13

 

-

 

A 5

 

X 6 Cr Ni Mo Ti 1712

 

1.4571

 

0.10

 

1.0

 

2.0

16.5

to 18.5

2.0

to 2.5

10.5

to 13.5

 

Ti ≥ 5 X

% C