Basic Steel Selection Based on BS 970
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| STEEL |
Notes |
| Carbon Steel |
| BS970-230M07(EN1A) |
A free cutting mild steel giving good machined
finish. Excellent high speed machining |
| BS970-070M20(EN3) |
A '20' carbon mild steel.Used for general purpose
mild steel. |
| BS970-080M30(EN6) |
Generally provided in square and flat bar known
as key steel. |
| BS970-080M40(EN8) |
A '40' carbon mild steel. A good all round steel
for applications requiring added strength |
| BS970-070M55(EN9) |
A special mild case hardening steel which can
provide a hard wearing surface with a tough core. |
| BS970-080M15(EN32) |
A special mild case hardening steel which can
provide a hard wearing surface with a tough core. |
| Alloy Steel |
| BS970 605M36 (EN16) |
A general purpose alloy high tensile steel |
| BS970 790M40(EN19) |
A 1% chromium molybdenum high tensile steel.
Suitable for highly stressed applications where greater strength
is required |
| BS970 817M40(EN24) |
A nickel chromium molybdenum high tensile steel.
Has good wear and shock resistance and is suitable for tensile
ranges up to100 tonnes. |
| BS 970 835M30 (EN30B) |
A 4.25% nickel steel. Achieves a good through
hardness with air or oil hardening. It is capable of taking a
good polish and is widely used as a plastic mould steel. |
| BS970 655M13 (EN36) |
A nickel chomium case hardening steel. Gives a
very hard surface with a strong core and retaining a high degree
of toughness. |
| BS970 722M24 (EN40B) |
A 3% chromium molybdenum nitriding steel. It will
achieve a good core strength with a hard nitrided surface. The
nitriding process leaves the component scale free. |
| BS970 905M31(EN41) |
A 1.5% chromium aluminium molybdenum nitriding
steel. It gives a very hard nitrided surface with a high core
strength |
| Stainless Steel |
| BS970 Grade 416 |
13% chromium, free machining stainless. Usually
supplied ready heat treated and offering excellent machining
properties. |
| BS970 Grade 420 |
13% chormium stainless steel which will achieve a
high hardness. It gives a good polish and is resistant to attack
from corrosive plastics |
| BS970 Grade 431 |
17% chromium 2.5% nickel stainless. Supplied heat
treated with a high tensile strength. |
| BS970 Grade 304 |
18% chromium. 9% nickel stainless. Good all round
austenitic grade for general purpose corrosion resistant
applications |
| BS970 Grade 321 |
18% chromium. 10% nickel stainless. Similar to
304 but titanium stabilized, which offes improved welding
properties. |
| BS970 Grade 303 |
18% chromium. 9% nickel free machining stainless.
It offers good corrosion resistance with better machinability. |
| BS970 Grade 316 |
18% chromium, 1% nickel, 2.5% molybdenum
stainless. It offers high resistance to corrosion |
| BS970 Grade 310 |
25% chromium, 20% nickel stainless. A heat
resisting stainless with good resistance to scaling at high
temperatures. |
Selection Of Steels
| Type Of Steel |
BS Spec
BS970 |
Composition %
C-Mn-Ni-Cr-Mo |
Condition |
Yield Stress x 106 Pa |
Tensile Stress x106 Pa |
Elongation % |
| Low Carbon Steel |
040A10 |
0.1-0.4-0-0-0 |
- |
- |
300 |
28 |
| Constructural Steel |
080M40 |
0.4-0.8 |
- |
500 |
700 |
20 |
| Low Manganese |
150M28 |
0.28-1.5-0-0 |
Heat Treat |
355 |
587 |
20 |
| Nickel Manganese |
503M40 |
0.4-0.9-1.0 |
Heat Treat |
494 |
695 |
25 |
| Manganese Molybdenum |
608M38 |
0.38-1.5-0-0-0.5 |
Heat Treat |
1000 |
1130 |
19 |
| Nickel Chromium |
633M31 |
0.31-0.60-3.0-1.0 |
Heat Treat |
819 |
927 |
23 |
| Nickel-Chrom-Mo |
817M40 |
0.4-0.55-1.5 -1.2-0.3 |
Heat Treat |
988 |
1080 |
22 |
| Nickel-Chrom-Mo |
835M30 |
0.3-0.55-4.25-1.25-0.3 |
Heat Treat |
1470 |
1700 |
14 |
| Mang-Ni-Chr-Mo |
945M38 |
0.38-1.4-0.75-0.5-0.20 |
Heat Treat |
958 |
1040 |
85 |
| Steel Ferritic |
403S17 |
0.04-0.45-0-14.0-0 |
Soft |
340 |
510 |
31 |
| Stainless Martensitic |
420S45 |
0.3-0.5-0-13.0-0 |
Heat Treat |
- |
1470-1670 |
- |
| 18/8 Stainless Austenitic |
302S25 |
0.05-0.8-8.5-18.0-0 |
Soft |
278 |
618 |
50 |
| 18/8 Stainless Austenitic |
302S25 |
0.05-0.8-8.5-18.0-0 |
Cold work |
803 |
896 |
30 |
| 18/8 St. (No Weld Decay) |
321S20 |
0.05-0.8-8.5-18.0-0-1.6Ti |
Softened |
278 |
618 |
50 |
| 18/8 St. (No Weld Decay) |
321S20 |
0.05-0.8-8.5-18.0-0-1.6Ti |
Cold Worked |
402 |
803 |
30 |
Relevant Steel Links
- British Stainless Steel
Association Properties /Relevant Standards for Stainless Steels
- Dansk
Steel WorksClick on Products > Standards for Information on
European Steel Standards/properties
BS970 designation
The BS970 code number is constructed as follows;
a) The first three symbols are a number code indicating the type
of steel:
000 to 199 Carbon and carbon-manganese steels. The number represents
the manganese content x 100
200 to 240 Free cutting steels. The second and third number indicate
the sulphur content x 100
250 Silicon Manganese valve steels
300 to 499 Stainless and heat resisting steels
500 to 999 Alloy Steels
b) The fourth symbol is a letter code .
A The steel is supplied to a chemical compostion determine buy
analysis of the batch sample.
H The steel is supplied to a hardenability specification
M The steel is supplied to a Mechanical Property specification.
S The steel is a stainless steel
c) The fifth and sixth symbol is a number is the actual mean
carbon content x 100
In addition to the above coding a condition coding may be applied.
indicating the tensile strength range after heat treatment. This is used
in conjunction with a limiting section designation.
