Stainless Steel 420
Stainless Steel 420 – High-Hardness Martensitic Stainless for Surgical Instruments and Blades
Stainless Steel 420 is a medium-carbon martensitic stainless steel that can be hardened to very high surface hardness levels, making it the material of choice for surgical instruments, knife blades, and plastic injection molds. Its 0.15%+ carbon content enables superior hardness and edge retention after heat treatment, with excellent polishability for mirror finishes.
Key Properties
- Tensile Strength: 586 MPa (annealed)
- Max Hardness: Up to ~50 HRC (hardened)
- Carbon Content: 0.15–0.40%
- Polishability: Excellent — mirror finish capable
- Standard: ASTM A276
Common Applications
Surgical and dental instruments, cutlery and knife blades, plastic injection molds requiring mirror polish, scissors, razors, and cutting tools requiring a combination of hardness and stainless properties.
Material properties
| Material name | Stainless Steel 420 |
|---|---|
| Type | Stainless Steel |
| Standard code | ASTM A276 |
| Tensile strength (MPa) | 586 |
| Yield strength (MPa) | 345 |
| Fatigue strength (MPa) | 345 |
| Elongation (%) | 25 |
| Hardness (Brinell) | 235 |
| Density (g/cm³) | 7.74 |
| Electrical resistivity (µΩ·in) | 55 |
| Thermal conductivity (W/m·K) | 24.9 |
| Melting range (°C) | 1450–1510 |
| Weldability | Poor |
| Formability | Poor |
| Shear modulus | 74 |
| Industry code | ss_420 |