Chemical composition of stainless steels to BS 970
Introduction
BS 970 has covered a wide range of long product forms steel grades and finishes. Stainless steels have appeared in various parts of different issues of BS 970, but were last shown only in parts 1 and 3. BS 970 also covered some low alloy steel grades as well as stainless steels. With the exception of forged bars, all stainless steels are now withdrawn from all parts of BS 970 and are now covered by either BS EN 10088-3, (stainless grades), or BS EN 10095, (heat-resisting grades). BS 970 should not be used for specifying new products, but may still be included in specifications for products originally designed before 1995 and so is included here for reference purposes only.
Long products for pressure purposes are now covered be BS EN 10272
A more detailed explanation of long product standards can be found in the BSSA publication ‘A specifiers guide to the new EN standards for stainless steel long products’ here :- Long Products Special Report.’
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The data given is not intended to replace that shown in individual standards to which reference should always be made.
BS 970 chemical composition table
| Grade |
| Chemical composition (% by mass – max unless stated) |
| – |
C |
Si |
Mn |
S |
P |
Cr |
Ni |
Mo |
Others |
| Ferritic steels |
| 403S17 |
0.08 |
1.00 |
1.0 |
0.030 |
0.040 |
12.0/14.0 |
0.50 |
– |
– |
| 430S17 |
0.08 |
1.00 |
1.0 |
0.030 |
0.040 |
16.0/18.0 |
0.50 |
– |
– |
| Martensitic steels |
| 410S21 |
0.09/0.15 |
1.00 |
1.0 |
0.030 |
0.040 |
11.5/13.5 |
1.00 |
– |
– |
| 416S21 |
0.09/0.15 |
1.00 |
1.5 |
0.15/0.35 |
0.060 |
11.5/13.5 |
1.00 |
0.60 |
– |
| 416S29 |
0.14/0.20 |
1.00 |
1.5 |
0.15/0.35 |
0.060 |
11.5/13.5 |
1.00 |
0.60 |
|
| 416S37 |
0.20/0.28 |
1.00 |
1.5 |
0.15/0.35 |
0.060 |
12.0/14.0 |
1.00 |
0.60 |
|
| 416S41 |
0.09/0.15 |
1.00 |
1.5 |
0.060 |
0.060 |
11.5/13.5 |
1.00 |
0.60 |
Se: 0.15/0.35 |
| 420S29 |
0.14/0.20 |
1.00 |
1.0 |
0.030 |
0.040 |
11.5/13.5 |
1.00 |
– |
– |
| 420S37 |
0.20/0.28 |
1.00 |
1.0 |
0.030 |
0.040 |
12.0/14.0 |
1.00 |
– |
– |
| 431S29 |
0.12/0.20 |
1.00 |
1.0 |
0.030 |
0.040 |
15.0/18.0 |
2.0/3.0 |
– |
– |
| Austenitic steels |
| 302S31 |
0.12 |
1.00 |
2.0 |
0.030 |
0.045 |
17.0/19.0 |
8.0/10.0 |
– |
– |
| 304S11 |
0.030 |
1.00 |
2.0 |
0.030 |
0.045 |
17.0/19.0 |
9.0/12.0 |
– |
– |
| 303S15 |
0.06 |
1.00 |
2.0 |
0.030 |
0.045 |
17.5/19.0 |
8.0/11.0 |
– |
– |
| 304S31 |
0.07 |
1.00 |
2.0 |
0.030 |
0.045 |
17.0/19.0 |
8.0/11.0 |
– |
– |
| 321S31 |
0.08 |
1.00 |
2.0 |
0.030 |
0.045 |
17.0/19.0 |
9.0/12.0 |
– |
Ti: 5C/080 |
| 347S31 |
0.08 |
1.00 |
2.0 |
0.030 |
0.045 |
17.0/19.0 |
9.0/12.0 |
– |
Nb: 10C/1.0 |
| 316S11 |
0.030 |
1.00 |
2.0 |
0.030 |
0.045 |
16.5/18.5 |
11.0/14.0 |
2.00/2.50 |
– |
| 316S13 |
0.030 |
1.00 |
2.0 |
0.030 |
0.045 |
16.5/18.5 |
11.5/14.5 |
2.50/3.00 |
– |
| 316S31 |
0.07 |
1.00 |
2.0 |
0.030 |
0.045 |
16.5/18.5 |
10.5/13.5 |
2.00/2.50 |
– |
| 316S33 |
0.07 |
1.00 |
2.0 |
0.030 |
0.045 |
16.5/18.5 |
11.0/14.0 |
2.50/3.00 |
– |
| 320S31 |
0.08 |
1.00 |
2.0 |
0.030 |
0.045 |
16.5/18.5 |
11.0/14.0 |
2.00/2.50 |
Ti: 5C/0.80 |
| 310S31 |
0.15 |
1.50 |
2.0 |
0.030 |
0.045 |
24.0/26.0 |
19.0/22.0 |
– |
– |
| 303S31 |
0.12 |
1.00 |
2.0 |
0.15/0.35 |
0.060 |
17.0/19.0 |
8.0/10.0 |
1.00 |
|
| 303S42 |
0.12 |
1.00 |
2.0 |
0.060 |
0.060 |
17.0/19.0 |
8.0/10.0 |
1.00 |
Se: 0.15/0.35 |
| 325S31 |
0.12 |
1.00 |
2.0 |
0.15/0.35 |
0.045 |
17.0/19.0 |
8.0/11.0 |
– |
Ti: 5C/090 |
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