BS 970:1955 EN325: EN325: Low nickel-chromium-molybdenum case-hardening steel, suitable for tensile strength 55 tons/sq in min. Specified in BS 970:1955, Part 2.
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Si
Mn
Ni
Cr
Mo
S
P
<=0.22
0.10-0.35
0.45-0.65
1.50-2.00
0.40-0.60
0.20-0.30
<=0.050
<=0.050
Mechanical Properties
Tensile Strength
≥849 MPa (55 tons/sq in, converted)
Elongation
≥15%
Condition
core, min (lowest-strength condition of the standard)
More data from BS 970:1955
From the standard
Condition of material on delivery
A
Bars and billets for forging as rolled or forged.
B
Forgings and drop-forgings as forged.
C
Bars for machining as rolled.
D
Bright bars cold worked, condition suitable for machining; max Brinell may be agreed.
Source: BS 970:1955, Part 2, En 325 (page 190)
Mechanical properties
Condition
Ruling section or size (in)
Tensile strength (tons/sq in)
Yield stress (tons/sq in)
Elongation (%)
Izod impact (ft lb)
Brinell (HB)
Proof stress 0.2% (tons/sq in), when requested
core, min
-
55
-
15
30
-
-
Values as printed in BS 970:1955; tensile strength, yield stress and proof stress in tons/sq in, Izod in ft lb. Minimum unless a range is shown.
Source: BS 970:1955, Part 2, En 325 (page 191)
Heat treatment
Blank carburise (1 1/8 in diameter test bars)
880/930 C
Refine (1 1/8 in diameter test bars)
850/880 C, cool in air, oil or water
Harden (oil) (1 1/8 in diameter test bars)
770/800 C
Temperatures in degrees C as printed.
Source: BS 970:1955, Part 2, En 325 (page 190)
Notes
Note
See Appendix A for single quench; by arrangement tests on samples without blank carburising or with short heating.
Source: BS 970:1955, Part 2, En 325
Status in the 1955 edition
Status
Deleted by Amendment 8
Reason
Amendment 8 (Jul 1971): alloy case hardening steels moved to BS 970 Part 3:1971
BS 970:1955 was amended up to Amendment 10 (June 1972); steels were moved to the revised Parts 1 to 5 and deleted from this edition.
Source: BS 970:1955, Amendment slips 6 to 10
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