BS 970 (Part 1):1983 665H20: 665H20 is a case hardening alloy steel grade supplied to hardenability (H) requirements, specified in BS 970 Part 1:1983 (Table 10, category 2). 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
Mo
Ni
P
S
0.17-0.23
0.35-0.75
0.20-0.30
1.50-2.00
<=0.035
<=0.040
More data from BS 970 (Part 1):1983
From the standard
Other composition limits
Phosphorus and sulphur
P 0.035 max, S 0.040 max, alloy steels (clause 1.7.2.1)
Residual elements: see clause 1.7.3.
Source: BS 970 (Part 1):1983, clause 1.7.2.1
Heat treatment and maximum hardness
Preheat treatment temperature (hardenability test)
930-950 deg C
Austenitizing temperature (hardenability test)
925 deg C
Maximum hardness HB, bars and billets for forging
207
Maximum hardness HB, forgings and bars for machining, normalized
207
Maximum hardness values apply when specified on the order, in the condition of delivery. Quantities not limited in Table 12 are not shown.
Source: BS 970 (Part 1):1983, Table 12
Hardenability requirements (end quench test)
Distance from quenched end (mm)
HRC max
HRC min
1.5
48
41
3
45
35
5
41
26
7
37
22
9
32
20
11
29
-
13
27
-
15
25
-
20
23
-
25
21
-
30
20
-
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 10
Comparison with earlier editions
BS 970:1970/72 designation
665H20
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
Active BS 970 (Part 1):1983 665H20 Listings on M-EX (For Sale)