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
S
P
0.30-0.35
0.10-0.35
0.70-0.90
0.60-1.00
<=0.050
<=0.050
Mechanical Properties
Tensile Strength
≥541 MPa (35 tons/sq in, converted)
Yield Strength
≥309 MPa (20 tons/sq in, converted)
Elongation
≥20%
Hardness
152-207 HB
Condition
Normalised, ruling section 6 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 finally heat treated unless order states otherwise.
C
Bars for machining finally heat treated 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 12A (page 66)
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
Normalised
6
35
20
20
15
152-207
-
Normalised
4
35
20
20
20
152-207
-
Hardened and tempered Q
6
40
30
22
25
179-229
-
Hardened and tempered Q
4
40
30
22
35
179-229
27
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 12A (page 67)
Heat treatment
Normalise (material required normalised)
830/860 C
Harden (oil) (material required hardened and tempered)
830/860 C
Temper (material required hardened and tempered)
suitable temperature between 550 C and 660 C
Temperatures in degrees C as printed.
Source: BS 970:1955, Part 2, En 12A (page 66)
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 EN12A Listings on M-EX (For Sale)