BS 970 (Part 3):1991 817M40 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	T	> 150 ≤ 250	850-1000	650	13	40	35	635	248-302
Hardened and tempered + turned or ground	T	> 63 ≤ 150	850-1000	680	13	54	50	665	248-302
Hardened and tempered + turned or ground	U	> 29 ≤ 100	925-1075	755	12	47	42	740	269-331
Hardened and tempered + turned or ground	V	> 13 ≤ 63	1000-1150	850	12	47	42	835	293-352
Hardened and tempered + turned or ground	W	≥ 6 ≤ 29	1075-1225	940	11	40	35	925	311-375	(6)
Hardened and tempered + turned or ground	X	≥ 6 ≤ 29	1150-1300	1020	10	34	28	1005	341-401	(1)(6)
Hardened and tempered + turned or ground	Z	≥ 6 ≤ 29	1550 min.	1235	5	10	9	1125	444 min.	(1)(6)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	T	> 63 ≤ 150	850-1000	700	9	54	—	680	248-302
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	U	> 29 ≤ 100	925-1075	770	9	47	—	755	269-331
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	V	> 13 ≤ 63	1000-1150	865	9	47	—	850	293-352
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	W	≥ 6 ≤ 29	1075-1225	955	8	40	—	940	311-375	(4)(6)(7)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	X	≥ 6 ≤ 29	1150-1300	1035	7	34	—	1020	341-401	(4)(6)(7)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground	Z	≥ 6 ≤ 29	1550 min.	1250	3	11	—	1235	444 min.	(4)(6)(7)

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 6: Often ordered in the softened condition for machining and subsequent heat treatment to achieve these mechanical properties. Note 1: For cold drawn bar below 6 mm all mechanical properties to be agreed at enquiry and order. Note 6: Often ordered in the softened condition for machining and subsequent heat treatment to achieve these mechanical properties. Note 1: For cold drawn bar below 6 mm all mechanical properties to be agreed at enquiry and order. 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. Note 7: Cold drawn bars are not normally available in this tensile strength range. 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 7: Cold drawn bars are not normally available in this tensile strength range. 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 7: Cold drawn bars are not normally available in this tensile strength range.

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