Bars and billets for forging; forgings and drop-forgings; bars for machining; bright bars. Suitable for 55/65 (T), 60/70 (U), 65/75 (V) tons/sq in according to ruling section. En 20B same title.
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
Cr
Mo
S
P
0.20-0.30
0.10-0.35
0.40-0.70
0.50-1.00
0.50-0.80
<=0.050
<=0.050
Mechanical Properties
Tensile Strength
≥849 MPa (55 tons/sq in, converted)
Yield Strength
≥680 MPa (44 tons/sq in, converted)
Elongation
≥18%
Hardness
248-302 HB
Condition
Hardened and tempered T, 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 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 20A (page 96)
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 T
2 1/2
55
44
18
40
248-302
41
Hardened and tempered U
2 1/2
60
48
17
35
269-321
46
Hardened and tempered V
1 1/8
65
52
16
35
293-341
50
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 20A (page 97)
Heat treatment
Harden (oil or water)
850/900 C
Temper
suitable temperature between 550 C and 720 C
Note
Water hardening is more suitable for En 20A and oil hardening for En 20B.
Temperatures in degrees C as printed.
Source: BS 970:1955, Part 2, En 20A (page 96)
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 EN20A Listings on M-EX (For Sale)