IS 3431 — Steel for the manufacture of volute, helical and laminated springs for automotive suspension
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Scope
Indian Standard for hot-rolled steel bars and flats used to make volute, helical and laminated springs for automotive suspension. Covers five grades — 55Si7, 60Si7, 65Si7, 50Cr4V2 and 60Cr4V2 — with chemical composition, hardenability, mechanical properties, freedom from surface defects, straightness, dimensions and tolerances. Steel may be made by the open-hearth, electric or combined processes, and a minimum reduction ratio of 16:1 from ingot to product is required. General delivery conditions follow IS 8910. It is a steel specification: the finished spring is covered by IS 7906 (helical compression springs and automobile leaf-spring assemblies).
Grades covered by IS 3431
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Nearest equivalents |
|---|---|---|---|---|---|---|
| 60Si7 | — | Silicon spring steel (Indian standard), quenched and tempered | 0.55 – 0.65 | — | ≈ 780–900 | 9260, SUP7, 56Si7 |
Revision history and superseded standards
| Year | Change |
|---|---|
| 1965 | IS 3431:1965 — first edition |
| 1982 | IS 3431:1982 — current edition (third revision) |
| 2022 | reviewed and reaffirmed by BIS; three amendments in force |
Supersedes: IS 3431:1965 (first edition).
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