Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Mn
Cr
Mo
B
S
0.36-0.45
1.25-1.75
0.15-0.35
0.08-0.18
0.0005-0.005
0.03-0.06
More data from BS 970 (Part 1):1991
From the standard
Other composition limits
Category
Category 1 steel
Boron
Soluble boron 0.0005-0.005 %; total boron may be determined if the hardenability values are realized (note 18)
Sulphur
0.03-0.06 %
Category 1 steels are preferred for new designs and established designs (clauses 1.4 and 2.1). Category 2 steels are printed in italic type.
Source: BS 970 (Part 1):1991, Table 5
Hardenability, end quench testHardness band
Hardness band (HRC, minimum to maximum) by distance from the quenched end (mm)
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
Distance from quenched end (mm)
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
Maximum, HRC
60
60
60
60
60
60
59
59
59
58
58
57
56
55
54
Minimum, HRC
53
53
53
53
52
52
52
51
49
46
43
40
38
36
34
Requirements for the hardenability test; no mechanical properties are specified (Table 6).
Source: BS 970 (Part 1):1991, Table 5
Heat treatment requirements
Mechanical properties
None specified (through hardening boron steel)
Preheat treatment temperature, hardenability test
870-890 deg C
Austenitizing temperature, hardenability test
840 deg C
Quenching medium: O = oil, W = water. Where oil hardening is specified, a well agitated conventional oil or a proven synthetic quenchant may be used; synthetic quenchants shall not be used for test bars of material not supplied finally heat treated (note 24).
Source: BS 970 (Part 1):1991, Table 6
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