431 vs 420
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
431
Stainless Steel
431 is a nickel-bearing martensitic stainless that develops the best combination of hardness, toughness and corrosion resistance in the martensitic family. It is used for high-strength shafts and marine hardware.
Standards: DIN 1.4057 · AISI 431 · JIS SUS431 · GB 14Cr17Ni2
420
Stainless Steel
420 is a hardenable 13% chromium martensitic stainless used for cutlery, surgical instruments and wear parts. Note: DIN 1.2083 is the high-carbon (0.36–0.42% C) mold-steel variant of the 420 family, melted and specified for plastic mold cavities rather than general engineering use.
Standards: DIN 1.4021 · AISI 420 · JIS SUS420J1 · GB 20Cr13
Chemical composition compared (%)
| Element | 431 | 420 |
|---|---|---|
| C | ≤0.20 | ≥0.15 |
| Si | ≤1.00 | ≤1.00 |
| Mn | ≤1.00 | ≤1.00 |
| P | ≤0.040 | ≤0.040 |
| S | ≤0.030 | ≤0.030 |
| Cr | 15.00–17.00 | 12.00–14.00 |
| Ni | 1.25–2.50 | — |
Properties compared
| Property | 431 | 420 |
|---|---|---|
| Delivery condition | Hardened & tempered | Annealed (hardened for use) |
| Hardness (hardened) | 35–45 HRC typical | 48–55 HRC |
| Tensile strength | 860–1350 MPa (Q&T) | 655–1700 MPa (condition dependent) |
| Density | 7.70 g/cm³ | 7.70 g/cm³ |
| Magnetic | Yes | Yes |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: 431 · 420. Substitution decisions for certified parts stay with the design authority.