Steel

Low Carbon free cutting steels
Used extensively for turned parts for general engineering and more specifically the automotive industry.

Table 1
BS 970 No.
Old BS970 No (En No).
Type.
220M07
230M07
210M15
214M15
1A
no equivalent
32M
202
low carbon - free cutting
low carbon - free cutting
15 carbon - free cutting
15 carbon 1.3% manganese free cutting

Low carbon steels
The steels in this category are usually referred to as mild steels. They are particularly useful for bending, forming and case-hardening. They are useful for lightly stressed components and are available in several different forms including round, square, hexagonal and flat section.

Table 2
BS 970 No.
Old BS970 No (En No).
Type.
040A10
070M20
080A15
080M15
2A
3A & 3C
no equivalent
32
low carbon
20 carbon
low carbon
15 carbon

Medium carbon and carbon manganese steels
Of higher strength than mild steels these respond to heat treatment and include some types suitable for induction and flame hardening Depending on analysis and ruling section tensile strengths up to the T range 850-1000 N/mm may be obtained although 700-850 N/mm is more common. Applications include gears, shafts, racks, pinions, studs, bolts, nuts, rollers, etc.

Table 3
BS 970 No.
Old BS970 No (En No).
Type.
080M30
080M40
080A42
080M46
080M50
070M55
150M19
212M36
212M44
212A42
225M44
5
8
8D
no equivalent
43A
9
14A & 14B
8M
8M
8DM
no equivalent
30 carbon
40 carbon
42 carbon
46 carbon
50 carbon
55 carbon
19 carbon 1.5% manganese
36 carbon free cutting
44 carbon free cutting
42 carbon free cutting
44 carbon free cutting

Alloy Case-hardening Steels
When a hard wear resisting surface and a tough supporting core is required the choice of steel will depend on the ruling section and core strength required for the. component. Care should be taken in selecting heavily alloyed types for parts with a thin cross section such as gear teeth as through hardening can result in brittleness and loss of shock resistance.

Table 4
BS 970 No.
Old BS970 No (En No).
Type.
no equivalent
665M17
655M13
635M15
33
34
36
351
-
1.75% nickel molybdenum
3.25% nickel chromium
0.75% nickel chromium

Alloy Direct Hardening Steels
Steels in this group are available with a combination of alloying elements including nickel, chromium, molybdenum and vanadium. They are supplied in the softened condition. After machining they can be hardened and tempered to a range of tensile strengths. They can also be supplied in the finally heat treated condition, where they are machinable and can be put into service without further heat treatment. Induction hardening of the surface can also be carried out on many of the specifications if required. Suitable for a wide range of applications where high strength and resistance to shock is important.

Table 5
BS 970 No.
Old BS970 No (En No).
Type.
605M36
708M40
709M40
817M40
16
19A
19
24
1.5% manganese molybdenum
1% chromium molybdenum
1% chromium molybdenum (higher molybdenum)
1.5% nickel chromium molybdenum


Stainless Steels

Ferritic
These stainless steels are mostly used for decorative trim. They are low strength but have good ductility and can be easily formed. These steels are mostly used for domestic and automotive trim, food processing and catering equipment, vehicle exhaust systems etc.

Table 6
BS 970 No.
Old BS970 No (En No).
Type.
403S17
430S15
no equivalent
60
13 Cr. C 0.08 max
17 Cr. C 0.10

Martensitic
These grades can be hardened and tempered to give tensile strengths in the range 550-1000 N/mm. Typical applications include cutlery, surgical instruments, fasteners, valves, spindles and shafts. Martensitic steels are magnetic.

Table 7
BS 970 No.
Old BS970 No (En No).
Type.
410S21
420S29
420S45
431S29
416S21
416S41
416S37
416S29
56A
56B
56D
57
56AM
56AMR
56CM
56BM
13 Cr. C 0.12
13 Cr. C 0.17
13 Cr. C 0.32
17 Cr. 2.5 Ni. C 0.15
13 Cr. C 0.12. S bearing free machining
13 Cr. C 0.12. Se bearing free machining
13 Cr. C 0.24. S bearing free machining
13 Cr. C 0.17. S bearing free machining

Austenitic
These steels are non-magnetic and cannot be hardened and tempered in the normal manner although they do work harden. This group offers the highest resistance to corrosion and is used for components in the food, chemical, gas and oil industries as well as for domestic appliances, automotive parts, hospital equipment, yacht fittings etc.

Table 8
BS 970 No.
Old BS970 No (En No).
Type.
302S25
304S15
316S16
320S17
321S12
303S21
325521
303S41
326S36
58A
58E
58J
58J
58B & 58C
58M
58M
58M
no equivalent
Cr Ni 18/9, C 0.12
Cr Ni 18/9, C 0.06
Cr Ni Mo 17/11/2.5, C 0.07
Cr Ni Mo 17/11/2.5 + Ti, C 0.08
Cr Ni 18/9/Ti, C 0.12
Cr Ni 18/9, S bearing free machining
Cr Ni 18/9/Ti, S bearing free machining
Cr Ni 18/9, Se bearing free machining
Cr Ni Mo 17/11/2.5, Se bearing free machining


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Pages created by David Price - 9/08/95
This Information is an educational resource and is not to be reproduced (other than for private study) without written consent of the University of Southampton. copyright Dave Whatley 1995
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