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
0.37-0.44
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
25
30
35
40
Distance from quenched end (mm)
1.5
3
5
7
9
11
13
15
20
25
30
35
40
Maximum, HRC
60
60
59
59
58
57
56
55
52
47
40
30
Minimum, HRC
53
53
52
51
50
47
42
36
28
20
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
Active BS 970 (Part 1):1991 170H41 Listings on M-EX (For Sale)