Bars and billets for forging; forgings and drop-forgings; bars for machining; bright bars. Suitable for 45/55 (R) and 50/60 (S) 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
S
P
0.25-0.35
0.10-0.35
0.35-0.75
2.75-3.25
<=0.30
<=0.050
<=0.050
Mechanical Properties
Tensile Strength
≥695 MPa (45 tons/sq in, converted)
Yield Strength
≥494 MPa (32 tons/sq in, converted)
Elongation
≥22%
Hardness
201-255 HB
Condition
Hardened and tempered R, ruling section 4 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 21 (page 98)
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 R
4
45
32
22
40
201-255
32
Hardened and tempered S
2 1/2
50
38
20
40
223-277
36
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 21 (page 99)
Heat treatment
Harden (oil or water)
830/860 C
Temper
suitable temperature between 550 C and 650 C
Temperatures in degrees C as printed.
Source: BS 970:1955, Part 2, En 21 (page 98)
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 EN21 Listings on M-EX (For Sale)