Bright cold finished bars (cold drawn, turned or precision ground) for general engineering purposes, in straight lengths; alloy direct hardening steel (Table 16)
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
P
S
Cr
0.36-0.44
0.10-0.40
0.60-0.90
<=0.035
<=0.040
0.90-1.20
More data from BS 970 (Part 3):1991
From the standard
Other composition limits
Steel group
Alloy direct hardening steel (Table 16)
Condition of supply
Bright bars: cold drawn, turned or precision ground, in straight lengths
Maximum unless a range is stated.
Source: BS 970 (Part 3):1991, Table 16
Mechanical properties by heat treatment condition
Condition
Reference symbol
Size (mm)
Tensile strength Rm (MPa)
Yield Re, min (MPa)
Elongation, min (%)
Impact Izod, min (J)
Impact KCV, min (J)
Rp0.2, min (MPa)
Hardness HB
Notes
Hardened and tempered + turned or ground
R
> 63 ≤ 100
700-850
525
17
54
50
510
201-255
Hardened and tempered + turned or ground
S
≥ 6 ≤ 63
775-925
585
15
54
50
570
223-277
Hardened and tempered + turned or ground
T
≥ 6 ≤ 29
850-1000
680
13
54
50
665
248-302
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground
R
> 63 ≤ 100
700-850
540
12
54
—
525
201-255
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground
S
> 13 ≤ 63
775-925
600
11
54
—
585
223-277
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground
T
≥ 6 ≤ 29
850-1000
700
9
54
—
680
248-302
Condition letters P to Z are the tensile strength ranges of Table 29. Rp0.2 applies when specifically ordered (note 3). Hardness HB is for guidance only except in the softened condition (note 13). Impact: Izod, or KCV when the standard impact test is not required (option A.3).
Source: BS 970 (Part 3):1991, Table 21
Hardness in the softened condition
Turned, ground or cold drawn and finally softened, max
229 max.
Table 21, finally softened condition.
Source: BS 970 (Part 3):1991, Table 21
Heat treatment temperatures
Hardening temperature
850-880 deg C, oil
Tempering temperature
550-700 deg C
Normalizing, hardening and tempering temperatures as given in Tables 27 and 28 (clause 4.2); Table 22 hardening temperatures for case hardening steels.
Source: BS 970 (Part 3):1991, Table 28
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