Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Si
Mn
Ni
Cr
Mo
S
P
0.35-0.45
0.10-0.35
0.45-0.70
1.30-1.80
0.90-1.40
0.20-0.35
<=0.050
<=0.050
Mechanical Properties
Tensile Strength
≥772 MPa (50 tons/sq in, converted)
Yield Strength
≥587 MPa (38 tons/sq in, converted)
Elongation
≥20%
Hardness
223-277 HB
Condition
Hardened and tempered S, ruling section 6 in (lowest-strength condition of the standard)
Typical Available Sizes
Round Bar
20mm – 350mm dia
Flat Bar
25×10mm – 250×75mm
Sizes are indicative. Contact seller for exact availability.
More data from BS 970:1955
From the standard
Condition of material on delivery
A
Bars and billets for forging as rolled or forged unless order states otherwise.
B
Forgings and drop-forgings finally heat treated unless order states otherwise.
C
Bars for machining in the softened condition unless order states otherwise.
D
Bright bars finally heat treated, before or after cold work at manufacturer option, unless order states otherwise.
Source: BS 970:1955, Part 2, En 24 (page 104)
Mechanical properties
Condition
Ruling section or size (in)
Tensile strength (tons/sq in)
Yield stress (tons/sq in)
Elongation (%)
Izod impact (ft lb)
Brinell (HB)
Proof stress 0.2% (tons/sq in), when requested
Hardened and tempered S
6
50
38
20
40
223-277
36
Hardened and tempered T
6
55
44
18
40
248-302
41
Hardened and tempered U
4
60
48
17
35
269-321
46
Hardened and tempered V
2 1/2
65
52
16
35
293-341
50
Hardened and tempered W
1 1/8
70
58
15
30
311-375
55
Hardened and tempered X
1 1/8
75
63
14
25
341-388
59
Hardened and tempered Y
1 1/8
80
68
14
22
363-415
64
Hardened and tempered Z
1 1/8
100
85
8
8
444
80
Softened condition
-
-
-
-
-
<=277
-
Values as printed in BS 970:1955; tensile strength, yield stress and proof stress in tons/sq in, Izod in ft lb. Minimum unless a range is shown.
Source: BS 970:1955, Part 2, En 24 (page 105)
Heat treatment
Harden (oil)
820/850 C
Temper
suitable temperature not exceeding 660 C
Temperatures in degrees C as printed.
Source: BS 970:1955, Part 2, En 24 (page 104)
Status in the 1955 edition
Status
Deleted by Amendment 7
Reason
Amendment 7 (Sep 1970): direct hardening alloy steels moved to BS 970 Part 2:1970
BS 970:1955 was amended up to Amendment 10 (June 1972); steels were moved to the revised Parts 1 to 5 and deleted from this edition.