BS 970 (Part 1):1983 185H40: 185H40 is a boron steel grade specified in BS 970 Part 1:1983 (Table 6, category 1). Section three of the standard advises that category 1 steels be used for new designs and established designs whenever possible.
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Mn
S
Cr
Mo
B
P
0.36-0.43
1.25-1.75
0.03-0.06
0.15-0.35
0.08-0.18
0.0005-0.005
<=0.035
More data from BS 970 (Part 1):1983
From the standard
Other composition limits
Boron
Soluble boron 0.0005-0.005; total boron may be determined provided the hardenability values are realized (note 18)
Phosphorus and sulphur
P 0.035 max, S 0.040 max, alloy steels (clause 1.7.2.1)
Source: BS 970 (Part 1):1983, Table 6
Heat treatment and maximum hardness (through hardening)
Preheat treatment temperature (hardenability test)
870-890 deg C
Austenitizing temperature (hardenability test)
840 deg C
Softened condition
Not usually supplied in the softened condition; no mechanical properties specified
Source: BS 970 (Part 1):1983, Table 7
Hardenability requirements (end quench test)
Distance from quenched end (mm)
HRC max
HRC min
1.5
60
53
3
60
53
5
60
53
7
60
53
9
60
52
11
60
52
13
59
52
15
59
51
20
59
49
25
58
46
30
58
43
35
57
40
40
56
38
45
55
36
50
54
34
Rockwell C hardness at the stated distance from the quenched end in the end quench hardenability test. A dash means no value is specified. Preheat and austenitizing temperatures: see the heat treatment block.
Source: BS 970 (Part 1):1983, Table 9
Comparison with earlier editions
BS 970:1970/72 designation
Not listed
BS 970:1955 En No.
None
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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