303 vs 304
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.
303
Stainless Steel
303 is the free-machining version of 304, with sulfur (and often phosphorus) added to break chips. It is the standard bar grade for high-volume turned parts, at the cost of reduced corrosion resistance and weldability.
Standards: DIN 1.4305 · AISI 303 · JIS SUS303 · GB Y12Cr18Ni9
304
Stainless Steel
304 is the most widely used stainless steel in the world, an 18-8 austenitic grade balancing corrosion resistance, formability and weldability. It covers the majority of food, architectural and general industrial applications.
Standards: DIN 1.4301 · AISI 304 · JIS SUS304 · GB 06Cr19Ni10
Chemical composition compared (%)
| Element | 303 | 304 |
|---|---|---|
| C | ≤0.15 | ≤0.08 |
| Si | ≤1.00 | ≤0.75 |
| Mn | ≤2.00 | ≤2.00 |
| P | ≤0.20 | ≤0.045 |
| S | ≥0.15 | ≤0.030 |
| Cr | 17.00–19.00 | 18.00–20.00 |
| Ni | 8.00–10.00 | 8.00–10.50 |
| Mo | ≤0.60 (optional) | — |
| N | — | ≤0.10 |
Properties compared
| Property | 303 | 304 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Hardness | ≤262 HB (annealed) | ≤187 HB (annealed) |
| Tensile strength | 515–690 MPa | 515–720 MPa |
| Density | 7.90 g/cm³ | 7.90 g/cm³ |
| Yield strength | — | ≥205 MPa |
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: 303 · 304. Substitution decisions for certified parts stay with the design authority.