Bars and billets for forging; forgings and drop-forgings; bars for machining; bright bars. Suitable where higher core strength is required for nitriding than En 40B provides; purchaser recommended to consult the manufacturer.
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
V
S
P
0.30-0.50
0.10-0.35
0.40-0.80
<=0.40
2.50-3.50
0.70-1.20
0.10-0.30
<=0.050
<=0.050
Mechanical Properties
Tensile Strength
≥1313 MPa (85 tons/sq in, converted)
Yield Strength
≥1112 MPa (72 tons/sq in, converted)
Elongation
≥10%
Hardness
375-444 HB
Condition
Hardened and tempered (single condition), ruling section 2 1/2 in (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 unless order states otherwise.
B
Forgings and drop-forgings softened unless order states otherwise.
C
Bars for machining softened unless order states otherwise.
D
Bright bars finally heat treated, before or after cold work at manufacturer option, unless order states otherwise.
Source: BS 970:1955, Part 2, En 40C (page 138)
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
Hardened and tempered (single condition)
2 1/2
85
72
10
15
375-444
68
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 40C (page 139)
Heat treatment
Harden (oil)
900/940 C
Temper
suitable temperature between 570 C and 650 C
Stabilise and nitride
When required by the purchaser, followed by a stabilising treatment after rough machining at a temperature not lower than 520 C, and afterwards the parts nitrogen hardened by an approved process. Tests in hardened and tempered condition or, by arrangement, after a stabilising treatment or a blank nitriding treatment.
Temperatures in degrees C as printed.
Source: BS 970:1955, Part 2, En 40C (page 138)
Status in the 1955 edition
Status
Deleted by Amendment 7
Reason
Amendment 7 (Sep 1970): direct hardening alloy steels moved to BS 970 Part 2:1970
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
Active BS 970:1955 EN40C Listings on M-EX (For Sale)