Stainless Steel 303 vs 304: Machinability vs Corrosion Resistance
303 is optimized for machinability with added sulfur, making it ideal for high-volume turned parts. 304 offers better corrosion resistance and weldability, making it the standard for food, medical, and general-purpose applications.
Side-by-Side Property Comparison
| Property | Stainless Steel 303 | Stainless Steel 304 |
|---|---|---|
| Tensile Strength | 620 MPa (90 ksi) | 515 MPa (75 ksi) |
| Yield Strength | 240 MPa (35 ksi) | 205 MPa (30 ksi) |
| Hardness | 228 HB | 201 HB |
| Density | 8.03 g/cm³ | 8.00 g/cm³ |
| Machinability Rating | 78/100 | 45/100 |
| Thermal Conductivity | 16.2 W/m·K | 16.2 W/m·K |
| Melting Point | 1,400–1,420 °C | 1,400–1,450 °C |
| Tolerance | ±0.02 mm | ±0.02 mm |
Key Differences
| Property | Stainless Steel 303 | Stainless Steel 304 | Winner |
|---|---|---|---|
| Machinability | 78/100 | 45/100 | Stainless |
| Corrosion Resistance | Good | Excellent | Stainless |
| Weldability | Poor | Excellent | Stainless |
| Surface Finish | Excellent | Good | Stainless |
| Cost | Similar | Similar | Tie |
| Food Grade | No | Yes (food-safe) | Stainless |
Which Material Should You Choose?
Choose Stainless Steel 303 when:
- High-volume turned parts
- Complex screw machine parts
- Parts not requiring welding
- Shafts, fittings, and bushings
- Cost optimization for machined parts
Choose Stainless Steel 304 when:
- Food contact equipment
- Parts requiring welding
- Marine or corrosive environments
- Medical equipment
- Architectural applications
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