Stainless Steel 440C
Stainless Steel 440C – Highest-Hardness Stainless Steel for Bearings and Cutting Tools
Stainless Steel 440C is the highest carbon (1.0%) member of the 440 series and achieves the highest attainable hardness (~60 HRC) of any stainless steel. This extreme hardness combined with stainless properties makes it uniquely suited for precision bearings, valve balls, and cutting instruments operating in mildly corrosive environments where hardness and wear resistance are the overriding requirements.
Key Properties
- Tensile Strength: 759 MPa (annealed)
- Max Hardness: ~60 HRC after hardening
- Carbon Content: ~1.0%
- Hardness (annealed): 269 HB
- Weldability: Not recommended
- Standard: ASTM A276
Common Applications
Precision ball and roller bearings, valve balls and seats, surgical and dental instruments, cutting tools, pump components, and gauging instruments requiring maximum hardness in a stainless alloy.
Material properties
| Material name | Stainless Steel 440C |
|---|---|
| Type | Stainless Steel |
| Standard code | ASTM A276 |
| Tensile strength (MPa) | 759 |
| Yield strength (MPa) | 450 |
| Fatigue strength (MPa) | 517 |
| Elongation (%) | 14 |
| Hardness (Brinell) | 269 |
| Density (g/cm³) | 7.7 |
| Electrical resistivity (µΩ·in) | 60 |
| Thermal conductivity (W/m·K) | 24.2 |
| Melting range (°C) | 1370–1480 |
| Weldability | Not Recommended |
| Formability | Poor |
| Shear modulus | 74 |
| Industry code | ss_440c |