BS 970 (Part 3):1991 420S37: 420S37 is a stainless steel bright bar grade specified in BS 970 Part 3:1991 (bright bars for general engineering purposes).
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
Ni
0.20-0.28
<=1.0
<=1.0
<=0.040
<=0.030
12.0-14.0
<=1.00
More data from BS 970 (Part 3):1991
From the standard
Other composition limits
Steel group
Martensitic stainless steel (Table 17)
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 17
Heat treatment and mechanical properties
Heat treatment condition
Limiting ruling section (mm)
Tempering or heat treatment (deg C)
Tensile strength Rm (MPa)
Yield Re, min (MPa)
Elongation, min (%)
Impact Izod, min (J)
Impact KCV, min (J)
Rp0.2, min (MPa)
Hardness HB
R
150
650-750 (tempered)
700-850
525
15
< 63 mm: 34; ≥ 63 mm: 27
—
495
210-255
S
150
600-700 (tempered)
775-925
585
13
< 63 mm: 27; ≥ 63 mm: 14
—
555
223-277
Condition letters P to T are the tensile strength ranges of Table 29. Rp0.2 applies when specifically ordered (note 3). Bars of ferritic steel in the hardened and tempered condition are heat treated before or after cold sizing (clause 4.3.1). See also option A.3.
Source: BS 970 (Part 3):1991, Table 23
Hardness in the softened condition
Softened condition, max
229 HB
Table 23, softened condition.
Source: BS 970 (Part 3):1991, Table 23
Heat treatment temperatures
Hardening temperature
950-1020 deg C, oil or air hardened
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 23
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