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
Ni
0.12-0.18
0.25-0.50
1.00-1.40
0.15-0.30
3.90-4.30
Mechanical Properties
Condition
Case hardened, 19 mm test bar
Tensile Strength
1310 MPa min
Elongation
8 % min
More data from BS 970 (Part 1):1991
From the standard
Other composition limits
Category
Category 1 steel
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 8
Core properties after case hardening, by test bar diameter
Test bar diameter (mm)
Tensile strength, min (MPa)
Elongation, min (%)
Impact Izod, min (ft lb)
Impact KCV, min (J)
19
1310
8
25
28
Properties of simulated case hardened test bars (clause 1.13.3.4). 1 N/mm2 = 1 MPa. Note 29: these are new steels which may have been conservatively rated due to limited data.
Source: BS 970 (Part 1):1991, Table 8
Maximum hardness by condition of delivery
Bars and billets for forging, max
277 HB
Forgings and bars for machining, sub-critically annealed, max
277 HB
Forgings and bars for machining, normalized and tempered, max
269 HB
Maximum Brinell hardness when specified on the order, in the condition of delivery (Table 9).
Source: BS 970 (Part 1):1991, Table 9
Heat treatment
Hardening temperature
800-820 deg C (shall also be stress relieved at a temperature not exceeding 200 deg C, note 30)
Table 9: heat treatment of case hardening steels. Values as printed; a dash in the table means not specified.
Source: BS 970 (Part 1):1991, Table 9
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