321 vs 321H
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.
321
Stainless Steel
321 is a titanium-stabilised 18-10 stainless developed for welded equipment operating between 425 and 900 °C, where unstabilised 304 would sensitise. It is a long-standing aircraft and exhaust-system grade.
Standards: DIN 1.4541 · AISI 321 · JIS SUS321 · GB 06Cr18Ni11Ti
321H
Stainless Steel
321H is the high-carbon, titanium-stabilised variant of 321, combining sensitisation resistance with guaranteed creep strength for high-temperature pressure parts. It is used in boiler and refinery service where plain 321 lacks code strength values.
Standards: DIN 1.4878 · AISI 321H · JIS SUS321 · GB 07Cr19Ni11Ti
Chemical composition compared (%)
| Element | 321 | 321H |
|---|---|---|
| C | ≤0.08 | 0.04–0.10 |
| Si | ≤0.75 | ≤0.75 |
| Mn | ≤2.00 | ≤2.00 |
| P | ≤0.045 | ≤0.045 |
| S | ≤0.030 | ≤0.030 |
| Cr | 17.00–19.00 | 17.00–19.00 |
| Ni | 9.00–12.00 | 9.00–12.00 |
| Ti | 5×(C+N)–0.70 | 4×(C+N)–0.70 |
| N | ≤0.10 | ≤0.10 |
Properties compared
| Property | 321 | 321H |
|---|---|---|
| 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 |
| Creep service | — | Rated for pressure service above ~525 °C |
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: 321 · 321H. Substitution decisions for certified parts stay with the design authority.