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BS 970 (Part 1):1983 410S21 Steel: Specifications & Listings

BS 970 (Part 1):1983 410S21: 410S21 is a martensitic stainless steel grade specified in BS 970 Part 1:1983 (Table 13, category 1).

Category: Stainless Steel
Grade Details
GradeBS 970 (Part 1):1983 410S21
Standard BS 970 (Part 1):1983
ApplicationsStainless and heat resisting steel for mechanical and allied engineering purposes (Table 13).
Equivalent / Similar Grades
Grade Standard Region Live on M-EX
BS 970 EN56A BS 970:1955 UK No activity yet
IS 1570 (Part 7) 12Cr13H IS 1570 (Part 7):1992 India No activity yet
ASTM A959 414 ASTM A959:2011 USA No activity yet
BS 970 (Part 1) 410S21 BS 970 (Part 1):1991 UK No activity yet
ASTM A240/A240M S40300 ASTM A240/A240M:2025 USA No activity yet
ASTM A276/A276M S41400 ASTM A276/A276M:2017 USA No activity yet
IS 6603 X12Cr13 IS 6603:2024 India No activity yet
EN 10088-1 X12Cr13 EN 10088-1:2023 Europe (CEN) No activity yet
EN 10088-3 X12Cr13 EN 10088-3:2014 Europe No activity yet
JIS G4304 SUS403 JIS G4304:2021 Japan No activity yet
JIS G4304 SUS410 JIS G4304:2021 Japan No activity yet
Grade ComparisonCompare With a Specific Grade →
Grade Standard Match
BS 970 (Part 1) 410S21 BS 970 (Part 1):1991 Strong Match
BS 970 (Part 3) 410S21 BS 970 (Part 3):1991 Strong Match
IS 1570 (Part 5) X12Cr12 IS 1570 (Part 5):1985 Strong Match
IS 6911 X12Cr12 IS 6911:1992 Strong Match
IS 1570 (Part 7) 12Cr13H IS 1570 (Part 7):1992 Strong Match
ASTM A240/A240M S41000 ASTM A240/A240M:2025 Strong Match
IS 11169 (Part 2) X12Cr13 IS 11169 (Part 2):2023 Strong Match
IS 6603 X12Cr13 IS 6603:2024 Strong Match
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
0.09-0.15 <=1.0 <=1.0 <=0.040 <=0.030 11.5-13.5 <=1.00

More data from BS 970 (Part 1):1983

From the standard
Mechanical properties by heat treatment condition
ConditionLimiting ruling section (mm)Heat treatmentRm (N/mm2)Re min (N/mm2)A min (%)Izod min (ft lbf)KCV min (J)Rp0.2 min (N/mm2), when specifically orderedHB
P150Harden 950-1020 deg C (oil or air), temper 650-750 deg C (notes 33, 34)550-70037020<=63 mm: 40; >63 mm: 25-340152-207
R63Harden 950-1020 deg C (oil or air), temper 600-700 deg C (notes 33, 34)700-8505251525-495201-255
All Table 13 steels are category 1. Rp0.2 applies when specifically ordered (note 10). 1 N/mm2 = 1 MPa.
Source: BS 970 (Part 1):1983, Table 13
Hardness, softened condition
Hardness HB, softened condition
207 max
Source: BS 970 (Part 1):1983, Table 13
Comparison with earlier editions
BS 970:1970/72 designation
410S21
BS 970:1955 En No.
56A
Appendix D note 47: where a comparison is made the steels are not necessarily equivalent. 'Not listed' means the earlier edition has no entry under this designation.
Source: BS 970 (Part 1):1983, Appendix D

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