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
P
S
Cr
Ni
0.12-0.20
<=1.0
<=1.0
<=0.040
<=0.030
15.0-18.0
2.0-3.0
More data from BS 970 (Part 1):1983
From the standard
Mechanical properties by heat treatment condition
Condition
Limiting ruling section (mm)
Heat treatment
Rm (N/mm2)
Re min (N/mm2)
A min (%)
Izod min (ft lbf)
KCV min (J)
Rp0.2 min (N/mm2), when specifically ordered
HB
T
150
Harden 950-1020 deg C (oil or air), temper 650-650 deg C as printed (notes 33, 34, 35)
850-1000
680
11
<=63 mm: 25; >63 mm: 15
-
635
248-302
All Table 13 steels are category 1. Rp0.2 applies when specifically ordered (note 10). 1 N/mm2 = 1 MPa. Note 35: when 0.2% proof stress is specified, a double tempering treatment is recommended: (a) 640 to 680 deg C followed by (b) a second temper up to 610 deg C (lower limit not legible on the scan).
Source: BS 970 (Part 1):1983, Table 13
Hardness, softened condition
Hardness HB, softened condition
277 max
Source: BS 970 (Part 1):1983, Table 13
Comparison with earlier editions
BS 970:1970/72 designation
431S29
BS 970:1955 En No.
57
Appendix D note 47: where a comparison is made the steels are not necessarily equivalent. 'Not listed' means the earlier edition has no entry under this designation.
Source: BS 970 (Part 1):1983, Appendix D
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