BS 970 (Part 3):1991 080M50 Steel: Specifications & Listings

Maximum unless a range is stated.

Source: BS 970 (Part 3):1991, Table 13

Condition	Reference symbol	Size (mm)	Tensile strength Rm (MPa)	Yield Re, min (MPa)	Elongation, min (%)	Impact Izod, min (J)	Impact KCV, min (J)	Rp0.2, min (MPa)	Hardness HB	Notes
Normalized + turned or ground		≥ 6 ≤ 150	620 min.	310	14	—	—	—	179-229
Normalized + turned or ground		> 150 ≤ 250	570 min.	295	14	—	—	—	163-217
Normalized + cold drawn or normalized + cold drawn + ground		≥ 6 ≤ 13	740 min.	590	7	—	—	555
Normalized + cold drawn or normalized + cold drawn + ground		> 13 ≤ 16	730 min.	585	8	—	—	545
Normalized + cold drawn or normalized + cold drawn + ground		> 16 ≤ 40	690 min.	555	8	—	—	485
Normalized + cold drawn or normalized + cold drawn + ground		> 40 ≤ 63	680 min.	540	9	—	—	420
Normalized + cold drawn or normalized + cold drawn + ground		> 63 ≤ 76	650 min.	510	10	—	—	400
Hardened and tempered + turned or ground	Q	≥ 6 ≤ 150	625-775	390	15	—	—	360	179-229
Hardened and tempered + turned or ground	R	≥ 6 ≤ 63	700-850	430	14	—	—	400	201-255
Hardened and tempered + turned or ground	S	≥ 6 ≤ 29	775-925	495	14	—	—	465	223-277
Hardened and tempered + turned or ground	T	≥ 6 ≤ 13	850-1000	570	12	—	—	555	248-302	(4)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	Q	≥ 13 ≤ 150	625-775	430	11	—	—	390	179-229
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	R	≥ 6 ≤ 63	700-850	490	10	—	—	450	201-255
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	S	≥ 6 ≤ 29	775-925	540	10	—	—	500	223-277
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	T	≥ 6 ≤ 13	850-1000	595	9	—	—	550	248-302	(4)
Turned, ground or cold drawn and finally softened		—	—	—	—	—	—	—	187 max.

Condition letters P to Z are the tensile strength ranges of Table 29. Rp0.2 applies when specifically ordered (note 3). Hardness HB is for guidance only except in the softened condition (note 13). Impact: Izod, or KCV when the standard impact test is not required (option A.3). Note 4: These properties cannot always be obtained by bulk heat treatment of bar but can be achieved by the appropriate heat treatment of components by the purchaser. Note 4: These properties cannot always be obtained by bulk heat treatment of bar but can be achieved by the appropriate heat treatment of components by the purchaser.

Source: BS 970 (Part 3):1991, Table 20

Normalizing, hardening and tempering temperatures as given in Tables 27 and 28 (clause 4.2); Table 22 hardening temperatures for case hardening steels.

Source: BS 970 (Part 3):1991, Table 27 and Table 28