Steel Suppliers and stockholders - KV Steel Services, Darlaston, West Midlands

080M40 Steel

BS970/PD970: 1970 onwards 080M40
BS970: 1955 EN8.
Related European grades: C40, C45, Ck40,Ck45, Cm40, Cm45,
Werkstoff no. 1.0511, 1.1186, 1.1189.
US Grades: SAE (AISI) 1039, 1040, 1042, 1043, 1045.

080M40 is usually supplied untreated but can be supplied to order in the normalized or finally heat treated (quenched and tempered to "Q" or "R" properties for limiting ruling sections up to 63mm), which is adequate for a wide range of applications.  Please refer to our selection guide for comparisons.

080M40 is a very popular grade of through-hardening medium carbon steel, which is readily machinable in any condition. (Refer to our machinability guide). 080M40 is suitable for the manufacture of parts such as general-purpose axles and shafts, gears, bolts and studs.  It can be further surface-hardened typically to 50-55 HRC by induction processes, producing components with enhanced wear resistance.  For such applications the use of 080A42 (EN8D) is advisable.  It is also available in a free-machining version, 212A42 (EN8M)

080M40 in its heat treated forms possesses good homogenous metallurgical structures, giving consistent machining properties.

Good heat treatment results on sections larger than 63mm may still be achievable, but it should be noted that a fall-off in mechanical properties would be apparent approaching the centre of the bar.

It is therefore recommended that larger sizes of 080M40 are supplied in the untreated condition, and that any heat treatment is carried out after initial stock removal.  This should achieve better mechanical properties towards the core.

080M40 Specification
Chemical composition
Carbon 0.36-0.44%
Silicon 0.10-0.40%
Manganese 0.60-1.00%
Sulphur 0.050 Max
Phosphorus 0.050 Max
Chromium -
Molybdenum -
Nickel -


080M40 - mechanical properties in "R" condition
Max Stress 700-850 n/mm2  
Yield Stress 465 n/mm2 Min (up to 19mm LRS)
0.2% Proof Stress 450 n/mm2 Min (up to 19mm LRS)
Elongation 16% Min (12% if cold drawn)
Impact KCV 28 Joules Min (up to 19mm LRS
Hardness 201-255 Brinell  


080M40 Equivalents
BS970: 1955 EN8
European C40, C45, Ck40,Ck45, Cm40, Cm45
Werkstoff No. 1.0511, 1.1186, 1.1189
US SAE (AISI) 1039, 1040, 1042, 1043, 1045


KV Steel Services is a supplier of 080M40, 080A42 and 212A42 steel to local and national businesses. We stock 080M40 and 080A42 in bright bar and blocks and black bar, square, flats and blocks.

080M40 Steel Bar

quality supplier of 080M40 Steel