Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Mn
B
0.17-0.23
0.80-1.10
0.0005-0.005
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)
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
Distance from quenched end (mm)
1.5
3
5
7
9
11
13
15
20
Maximum, HRC
48
48
47
46
43
39
32
26
20
Minimum, HRC
41
40
36
26
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
910-930 deg C
Austenitizing temperature, hardenability test
905 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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