BS 970 (Part 3):1991 709M40 Steel: Specifications & Listings

Maximum unless a range is stated.

Source: BS 970 (Part 3):1991, Table 16

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
Hardened and tempered + turned or ground	R	> 100 ≤ 250	700-850	495	15	34	28	480	201-255
Hardened and tempered + turned or ground	S	> 150 ≤ 250	775-925	555	13	27	22	540	223-277
Hardened and tempered + turned or ground	S	> 63 ≤ 150	775-925	585	15	54	50	570	223-277
Hardened and tempered + turned or ground	T	> 29 ≤ 100	850-1000	680	13	54	50	665	248-302
Hardened and tempered + turned or ground	U	> 13 ≤ 63	925-1075	755	12	47	42	740	269-331
Hardened and tempered + turned or ground	V	≥ 6 ≤ 29	1000-1150	850	12	47	42	835	293-352	(4)(6)
Hardened and tempered + turned or ground	W	≥ 6 ≤ 19	1075-1225	940	12	40	35	925	311-375	(6)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	R	> 100 ≤ 150	700-850	540	11	54	—	510	201-255
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	S	> 63 ≤ 150	775-925	600	11	54	—	585	223-277
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	T	> 29 ≤ 100	850-1000	700	9	54	—	680	248-302
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	U	> 13 ≤ 63	925-1075	770	9	47	—	755	269-331
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	V	≥ 6 ≤ 29	1000-1150	865	9	47	—	850	293-352	(4)(6)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	W	≥ 6 ≤ 19	1075-1225	955	8	40	—	940	311-375

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 6: Often ordered in the softened condition for machining and subsequent heat treatment to achieve these mechanical properties. Note 6: Often ordered in the softened condition for machining and subsequent heat treatment to achieve these mechanical properties. 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 6: Often ordered in the softened condition for machining and subsequent heat treatment to achieve these mechanical properties.

Source: BS 970 (Part 3):1991, Table 21

Table 21, finally softened condition.

Source: BS 970 (Part 3):1991, Table 21

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 28