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
S
P
0.33-0.38
<=0.25
0.90-1.30
0.12-0.20
<=0.060
Mechanical Properties
Tensile Strength
≥541 MPa (35 tons/sq in, converted)
Yield Strength
≥278 MPa (18 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
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
18
20
-
152-207
-
Hardened and tempered Q
2
40
28
22
25
179-229
25
Hardened and tempered R
1/2
45
32
20
40
201-255
30
Cold drawn
1 1/2
38
-
12
-
<=229
-
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 8AM (page 60)
Heat treatment
Normalise
830/860 C
Harden (oil)
830/860 C
Temper
550/660 C
Temperatures in degrees C as printed.
Source: BS 970:1955, Part 2, En 8AM (page 59)
Status in the 1955 edition
Status
Deleted by Amendment 9
Reason
Amendment 9 (Feb 1972): carbon and carbon-manganese steels moved to BS 970 Part 1:1972
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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