Matter Index

BS 970 steels..

Basic Notes on steels..... Sample specifications......
BS 970 numbering system explained...... Modern equivalents to BS 970 1955;EN numbers......

Important Notes:

1) BS 970 has been generally superseded by European based standards Notes on European Standards
2) All information on this page has been interpreted from the relevent Standard, Books eg Newnes Mech. Eng Pocket Book, Kempe's, Other Web Sites, and Leaflets. This information is of a general nature for initial guidance.   Selection of materials for use must be by communication with the suppliers and by reference to the appropriate codes - The best standards to use are the European EN based standards -

Basic Steel Selection Based on BS 970

Typical selection of steels and useful notes

Carbon Steel
BS 970 230M07
A low carbon, free cutting, mild steel suitable for machining using automatic and CNC machines. Available as rolled or normalised in round, flat or hexagon form
BS 970 070M20
A mild steel used for general purposes. Suitable for lightly stressed fasteners ,shafts etc. Can be easily machined and welded. Available hot rolled, normalised, cold drawn or turned. Supplied in Black round or square , bright round square, flat and hexagon.
BS 970 080M30
A medium strength steel. Used to make, shafts, racks, pinions, studs, bolts, nuts, rollers, etc. Supplied as square bar, or round bar or flat.
BS 970 080M40
A medium strength steel. Suitable for stressed pins, shafts studs, keys etc. Available as rolled or normalised. Supplied as square bar, or round bar or flat.
BS 970 070M55
A hard wearing medium carbon steel which can be hardened. Available as hot rolled, normalised, Cold drawn or turned. Sections available black round, black square, bright round and black flat.
BS 970 080M15
A case hardening mild steel suitable for general engineering applications. When case hardened results in a hard surface with a tough core. Used for making gears cams and rollers etc. Supplied as black round bar and sections
Alloy Steel
BS 970 605M36
A manganese molydenum steel with good ductily and mechanical strength. Available in heat treated condition e.g (R,S,T).Supplied as black round or square bar and bright round or square, and hexagons.
BS 970 709M40
A 1% typical chromium molybdenum steel with higher molybdenum. Can be induction hardened. Used for gears, and high strength shafts etc. Suitable for higher strength applications when resistance to shock is required. Available annealed. Supplied as black round or square bar and bright round or square, and hexagons.
BS 970 817M40
A nickel chromium molybdenum steel with high strength and toughness. Used for gears axles and high strength studs. Supplied as rolled, annealed and hardened and tempered. Supplied as black round or square bar and bright round or square, and hexagons
BS 970 655M13
A high quality nickel chromium case hardening steel. Can be hardened to provide hard surface with a strong tough core. Used for high duty gears and shafts. Supplied in as-rolled condition in black square and round bar and bright round.
BS 970 722M24
A 3% chromium molybdenum nitriding steel. Provide good tough core strength with a hard nitrided surface for wear resistance. Supplied in as-rolled, annealed and hardened and tempered condition in black square and round bar.
Stainless Steel
BS970 416S21
Martensitic (Magnetic), can be hardened and tempered to give improved tensile strength. FM** grade. Typical applications include cutlery, surgical instruments, fasteners, valves, spindles and shafts.
BS 970 431S29
Martensitic (Magnetic). Supplied heat treated with a high tensile strength. Typical applications include cutlery, surgical instruments, fasteners, valves, spindles and shafts.
BS 970 430S15
typ (EN60)
Ferritic. Low Strength but good ductility. Used food processing and catering equipment and automotive trim,car exhaust systems etc.
BS 970 Grade 304S15
Austenitic (Non-Magnetic)Cannot be heat treated but work hardens. Readily formed and welded,used mainly in domestic, dairy and decorative appliances general purpose grade for corrosion resistant applications. This grade is the most widely used of all stainless steels. Its chemical composition,provide the best all-round performance S.S. at relatively low cost. It has excellent low temperature properties. Lower Carbon grades (S15 and less) have improved weldability.
BS 970 Grade 316S16
Austenitic (Non-Magnetic)Cannot be heat treated but work hardens. It offers high resistance to corrosion. Generally machined components and pipe fittings. This grade is almost as popular as the 304 grade the increased Mo content makes the steel more suitable for resisting pitting and crevice then 304 Grade.  Lower Carbon grades (S15 and less) have improved weldability.
BS 970 Grade 321S12
Austenitic (Non-Magnetic)Cannot be heat treated but work hardens. Titanium stabilized, which offers improved welding properties.
BS 970 Grade 310S31 Austenitic (Non-Magnetic). Pocesses good resistance to scaling at high temperatures. For continuous high temperature service in the range 850 - 1000oC.

Sample Steels Specifications

Typical steels with general specifications notes

Important Note:

The values below are not comprehensive and must be used with extreme care.
The strength values e.g. the proof stress and yield stress, reduce as the section increases.  In the tables below the relevant sections are often thin and so the strength values are maximum values.  Please refer to the relevant standards for important work..

Type Of Steel BS Spec
BS 970
Composition %
Condition Yield Stress x 106 Pa Tensile Stress MPa Elongation %
Low Carbon Steel 230M07 0,15C%  1,1%Mn Hot rolled 215 360 21
Low Carbon Steel 230M07 0,15C%  1,1%Mn HR -> CD (thin) 340 480 6
Low Carbon Steel 070M20 0,2C%  0,7%Mn Normalised 215 430 21
Low Carbon Steel 070M20 0,2C%  0,7%Mn HR->CD (thin) 440 560 10
Constructural Steel 080M40 0,4%C  0,8%Mn Normalised 280 550 16
Constructural Steel 080M40 0,4%C  0,8%Mn HR -> CD (thin) 530 660 7
Low Manganese 150M28 0,28%C  1,5%Mn Heat Treat(P) 355 587 20
Nickel Manganese 503M40 0,4%C  -0,9%Mn  1,0%Cr Heat Treat(R) 525 700 min 17
Manganese Molybdenum 608M38 0,38%C  1,5%Mn  0,5%Mo Heat Treat 1000 1130 19
Nickel Chromium 633M31 0,31%C  0,60%Mn  3,0%Ni
Heat Treat(U) 755 927 23
Nickel-Chrom-Mo 817M40 0,4%C  0,55%Mn  1,2%Cr
Heat Treat (W) 940 1075 11
Nickel-Chrom-Mo 835M30 0,3%C  0,55%Mn  4,25%Ni
1,25%Cr  0,3%Mo
Hard'n +Temp 1470 1700 14
Mang-Ni-Chr-Mo 945M38 0,38%C  1,4%Mn  0,75%Ni
0,5%Cr  0,20%Mo
Heat Treat (V) 850 1040 2
Steel Ferritic 403S17 0,08%C  1,0%Mn  13%Cr
Softened 280 420 20
Stainless Martensitic 420S45 0,3%C  0,5%Mn  13,0%Cr Heat Treat (R) 525 700 15
18/8 Stainless Austenitic 302S25 0,12%C  0,8%Mn  8,5%Ni
Softened 278 618 50
18/8 Stainless Austenitic 302S25 0,12%C  0,8%MN  8,5%Ni
Cold work 803 896 30
18/8 St. (No Weld Decay) 321S20 0,05%C  0,8%Mn  8,5%Ni
18,0%Cr  1,6Ti
Softened 278 649 45
18/8 St. (No Weld Decay) 321S20 0,05C  0,8%Mn  8,5%Ni
18,0%Cr  1,6Ti
Cold Worked 402 803 30

BS970 Numbering system explained

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 by 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. (See table below)

Condition Code Letter Tensile Strength (Mpa)
Min Max
P 550 700
Q 620 770
R 700 850
S 770 930
T 850 1000
U 930 1080
V 1000 1150
W 1080 1240
X 1150 1300
Y 1240 1400
Z 1540 -

Table of BS 970: 1955 EN equivalents
* Steel No Relate to European Numbering system BS EN 10027-2 - I will add numbers as I locate them
BS970 1955 EN steel Equivalent
EN No BS 970 NameNote.* Steel No
1A 230M07Low Carbon Free Cutting C 1.0715
1B 240M07Low Carbon Free Cutting C-
3A 070M20'20' C 1.0402
5 080M30'30' C1.1178/1.1179
5A 080A27'30' C 
5B 080A30'30' C1.0528
8 080M40'40'C1.0503/1.0511
8A 080A35'35'C 
8B 080A37'37'C 
8C 080A40'40'C1.1186
8D 080A42'42'C 
9 070M55'50'C1.1209/1.0535
43A 080A50'50'C1,1206
43B 080A47'47'C 
43C 080A52'52'C 
43D 080A62'62'C1.1221
43E 080A67'67'C 
1A 220M07 Low Carbon FC**  
1B 240M07 Low Carbon FC**  
8M 212M36 '36' C FC** 1.0726
15AM 216M36 '36' C' FC**  
8BM 212A37 '37' C FC**  
8DM 212M44 '42' C FC** ?1.0727
8M 212M44 '44' C FC**  
12 503M40 1% Ni 
12B 503A37 1% Ni 
12C 503A42 1% Ni  
11 526M60 1% Cr  
18 530M40 1% Cr 1.7035
18A 530A30 1% Cr 1.8401
18B 530A32 1% Cr 1.7033
18C 530A36 1% Cr  
18D 530A40 1% Cr 1.7035
31 534A99 1.5% Cr  
31 535A99 1.5% Cr  
16D 605M30 1.5% Mn/Mo (Water Hardening)  
16 605M36 1.0% Mn/Mo 1.7006
16B 605A32 1.0% Mn/Mo  
16C 605A37 1.0% Mn/Mo 1.5432
16M 605A32 1.5% Mn/Mo(FC**)  
111 640M40 1.25% Ni/Cr  
111A 640M40 1.25% Ni/Cr  
23 653M31 3.0% Ni/Cr  
19A 708M40 1.0% Cr/Mo 1.7223
19B 708A37 1.0% Cr/Mo 1.7220
19C 708A42 1.0% Cr/Mo  
19 709M40 1.0% Cr/Mo (Higher Mo)1.7225
40B 722M24 3.0% Cr/Mo (Nitriding)1.7361
13 785M19 1.5% Mn/Ni/Mo  
110 816M40 1.0% Ni/Cr/Mo (Low Mo)1.6582
24 817M40 1.0% Ni/Cr/Mo 1.6582/1.6565
25 826M31 2.5% Ni/Cr/Mo (Medium C) 
26 826M40 2.5% Ni/Cr/Mo (High C)1,6746
27 830M31 3.0% Ni/Cr/Mo 
30B 835M30 4.0% Ni/Cr/Mo1.6747
40C 897M39 3.25% Ni/Cr/Mo/Va (Nitriding) 
41A 905M31 1.5% Cr/Al/Mo (Nitriding)(Medium C)1.8509
41B 905M39 1.5% Cr/Al/Mo (Nitriding)(High C) 
100 945M38 1.5% Mn/Ni/Cr/Al/Mo 
100C 945A40 1.5% Mn/Ni/Cr/Al/Mo1.6546
351 635M15 0.75% Ni/Cr  
352 637M14 1.0% Ni/Cr  
36A 655M13 3.25% Ni/Cr 1.5752
36A 655M13 3.25% Ni/Cr 1.5752
BS970 1955 EN steel Equivalent
EN No BS 970 NameNote.*Steel No
39A 659M15 4.0% Ni/Cr  
34 665M17    
35A 665A22 1.5% Ni/Mo  
35 665M23 1.5% Ni/Mo  
35B 665A24 1.5% Ni/Mo  
361 805M17 0.5% Ni/Cr/Mo  
362 805M20 0.5% Ni/Cr/Mo  
363 805M25 0.5% Ni/Cr/Mo  
353 815M27 1.5% Ni/Cr/Mo  
354 820M27 1.75% Ni/Cr/Mo  
355 822M17 2.0% Ni/Cr/Mo  
36C 832M13 3.0% Ni/Cr/Mo 1.6657
351 635M15 0.75% Ni/Cr  
352 637M17 1% Ni/Cr  
36A 655M13 3.25% Ni/Cr  
39A 659M15 4.0% Ni/Cr  
34 665M17 1.75% Ni/Mo  
35 665M23 1.75% Ni/Mo  
361 805M17 0.5% Ni/Cr/Mo  
362 805M20 0.5% Ni/Cr/Mo 1.6522'3
363 805M25 0.5% Ni/Cr/Mo  
353 815M17 1.5% Ni/Cr/Mo  
354 820M17 1.75% Ni/Cr/Mo  
355 822M17 2.0% Ni/Cr/Mo  
36C 832M13 3.5% Ni/Cr/Mo 1.6657
39B 835M15 4.0% Ni/Cr/Mo  
43 080A22 '52'Carbon  
43E 080A67 '67'Carbon  
42 070A72 '52'Carbon  
44 060A96 '96'Carbon 1.1274
45 250A53 Silico-Manganese '53'Carbon 1.0904
45A 250A58 '58'Carbon  
45A 250A61 '61'Carbon  
47 735A50 1.0% Cr 1.8159
48 527A60 0.75% Cr/Va  
Stainless Steels
58A 302S25 CrNi 18/9 C 0,12 ..Aust 1.4828
58M 303S41 CrNi 18/9 S bearing FM**..Aust  
58E 304S15 CrNi 18/19 C 0,06 ..Aust 1.4301
58H 315S16 CrNiMo 17/10/1,5 C 0,07 ..Aust 
58J 316S16 CrNiMo 17/11/2,5 C 0,07 ..Aust 1.4401
58J 316S17 CrNiMo 17/12/2,5 +Ti C 0,08 ..Aust 1.4401
58B/58C 321S12 CrNi 18/9 +Ti C 0,08 ..Aust 1.4541
58B/58C 321S20 CrNi 18/9 +Ti C 0,12 ..Aust  
58M 325S21 CrNi 18/9 +Ti +S FM** ..Aust1.4305
54 331S40 NiCrW 14/14/2,5..Valve  
54A 331S42 NiCrW 14/14/2,5 + Mo ..Valve 
58F/58G 347S17 Cr/Ni 18/9/Nb/C 0,08 ..Aus1.4550
52 401S45 Si/Cr 3/8 ..Valve 
56A 410S21 13CrC0,12 Mart 1.4006
56AM 416S21 13Cr C 0,12 S FM** ..Mart 1.4005
56AM 416S41 13Cr C 0,12 Se FM** ..Mart 
56BM 416S29 13Cr C 0,17 S FM** ..Mart  
56C 416S37 13Cr C 0,24 S bearing FM** ..Mart 
56B 420S29 13Cr C 0,17..Mart1.4024
56C 420S37 13Cr C 0,24 ..Mart1.4021
56D 420S45 13Cr C 0,32..Mart 1.4028
60 430S15 17Cr C 0,10....Fer 1.4016
57 431S29 17Cr 2,5NI C 0,10....Mart 1.4057
59 443S65 CrNiSi 20,1.5,2..Valve  
Stainless Steels ...Aus = Austenitic, Mart = Martensitic, Fe = Ferritic. FC** = Free Cutting..
FM** = Free machining

Relevant Steel Links
  1. British Stainless Steel Association ..Properties /Relevant Standards for Stainless Steels
  2. Plymouth College ..Notes On Steels
  3. Material Cross Reference List..Coromant- Sandvik Comprehensive list of steels
  4. Australian Stainless Steel Development Agency ..Contains physical and mechanical properties
  5. Steel grade equivalents ..Single page conversion sheet.-
  6. Casti Metals Black Book ..Download Document. A comprehensive reference text on european metals including Ref to latest Standards
  7. Matweb... The best source of material Information in the Web

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