310 vs 309
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.
310
Stainless Steel
310 is a 25Cr-20Ni heat-resistant austenitic grade with excellent oxidation resistance up to about 1035 °C in continuous service. Its higher carbon gives better high-temperature strength than 310S but more carbide precipitation on welding.
Standards: DIN 1.4841 · AISI 310 · JIS SUS310 · GB 12Cr25Ni20
309
Stainless Steel
309 is a high-chromium, high-nickel austenitic grade developed for elevated-temperature oxidation resistance. It also serves as a buffer or cladding layer when joining stainless to carbon steel.
Standards: DIN 1.4828 · AISI 309 · JIS SUS309 · GB 12Cr23Ni13
Chemical composition compared (%)
| Element | 310 | 309 |
|---|---|---|
| C | ≤0.25 | ≤0.20 |
| Si | ≤1.50 | ≤1.00 |
| Mn | ≤2.00 | ≤2.00 |
| P | ≤0.045 | ≤0.045 |
| S | ≤0.030 | ≤0.030 |
| Cr | 24.00–26.00 | 22.00–24.00 |
| Ni | 19.00–22.00 | 12.00–15.00 |
Properties compared
| Property | 310 | 309 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness | ≤217 HB (annealed) | ≤217 HB (annealed) |
| Tensile strength | 515–690 MPa | 515–690 MPa |
| Density | 7.90 g/cm³ | 7.90 g/cm³ |
| Max scaling temperature | ~1035 °C continuous | ~980 °C continuous |
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: 310 · 309. Substitution decisions for certified parts stay with the design authority.