Overview
SCM440 (AISI 4140) is a chromium-molybdenum alloy steel. It hardens deeper than carbon steel and, quenched and tempered, delivers high strength with good toughness and fatigue resistance.
It is a standard material for highly stressed shafts, bolts and tooling components.
Key Properties
Typical values from the MatWeb datasheet for AISI 4140 Steel, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled, 25 mm (1 in.) round. Machined parts take the properties of the stock they are cut from.
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Tensile strength | 655 MPa |
| Yield strength | 415 MPa |
| Elongation at break | 25.7 % |
| Hardness | HB 197 |
| Modulus of elasticity | 205 GPa |
| Thermal conductivity | 33 W/m-K |
| Machinability | 65 % |
Typical Applications
- High-load shafts and spindles
- Bolts and studs
- Gears and couplings
- Mold and die components
Machining Notes
Datasheet values are annealed. If the part should not be heat treated after machining, ask us about pre-hardened (Q&T) bar.
