Steel 4140
Steel 4140 – Versatile Chromium-Molybdenum Alloy Steel for High-Strength Applications
Steel 4140 is the most versatile chromium-molybdenum alloy steel in the engineering industry. Its combination of high hardenability, excellent fatigue resistance, and good impact toughness in the quenched-and-tempered (Q&T) condition makes it suitable for an extraordinarily wide range of structural and mechanical components across industries.
Key Properties
- Tensile Strength: 655 MPa (Q&T)
- Yield Strength: 415 MPa
- Elongation: 25%
- Hardness: 197 HB
- Weldability: Good (preheat recommended)
- Standards: ASTM A322 / AMS 6349
Common Applications
Gears, shafts, spindles, bolts, tooling fixtures, hydraulic components, connecting rods, and any high-stress mechanical application requiring deep hardenability and fatigue resistance.
Material properties
| Material name | Steel 4140 |
|---|---|
| Type | Carbon & Alloy Steel |
| Standard code | ASTM A322 / AMS 6349 |
| Tensile strength (MPa) | 655 |
| Yield strength (MPa) | 415 |
| Fatigue strength (MPa) | 310 |
| Elongation (%) | 25 |
| Hardness (Brinell) | 197 |
| Density (g/cm³) | 7.85 |
| Electrical resistivity (µΩ·in) | 22 |
| Thermal conductivity (W/m·K) | 42.7 |
| Melting range (°C) | 1416–1460 |
| Weldability | Good |
| Formability | Good |
| Shear modulus | 80 |
| Industry code | carbon_4140 |