Bars and billets for forging; forgings and drop-forgings; bars for machining; bright bars. Suitable for 50/60 (S), 55/65 (T), 60/70 (U), 65/75 (V) tons/sq in according to ruling section.
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
0.25-0.35
0.10-0.35
0.45-0.70
2.75-3.50
0.50-1.00
<=0.65
<=0.050
<=0.050
Mechanical Properties
Tensile Strength
≥772 MPa (50 tons/sq in, converted)
Yield Strength
≥587 MPa (38 tons/sq in, converted)
Elongation
≥20%
Hardness
223-277 HB
Condition
Hardened and tempered S, 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 23 (page 102)
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 S
6
50
38
20
40
223-277
36
Hardened and tempered T
6
55
44
18
40
248-302
41
Hardened and tempered U
6
60
48
17
35
269-321
46
Hardened and tempered V
2 1/2
65
52
16
35
293-341
50
Softened condition
-
-
-
-
-
<=269
-
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 23 (page 103)
Heat treatment
Harden (oil)
820/850 C
Temper
suitable temperature between 550 C and 660 C
Temperatures in degrees C as printed.
Source: BS 970:1955, Part 2, En 23 (page 102)
Notes
Note
Molybdenum optional (see Clause 4 c). If an adequate content of molybdenum is not present it is preferable to cool in oil or water after tempering.
Source: BS 970:1955, Part 2, En 23
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 EN23 Listings on M-EX (For Sale)