What is 4340 steel used for
AISI 4340 (E4340) alloy steel is a medium carbon, low alloy steel known for its toughness and strength. Machining is done typically in the annealed condition. 4340 steel properties offer good ductility in the annealed condition, allowing it to be bent or formed. Fusion and resistance welding is also possible with our 4340 steel from stock.
4340 steel is known for its strength and toughness. These characteristics come from the fine and equal dispersion of carbides within its structures. Other key features include:
- Fatigue and wear resistance
- Atmospheric corrosion resistance
- Formability, machinability, and heat treatability
4340 steel is used in a wide range of applications across various industries, including aerospace, automotive, and tooling. Typical uses include:
- Automotive systems
- Blades
- cylinder shafts
- cylinder barrels
- Heavy machinery
- Military aircraft
- Rotor shafts
- Tools
- Turbine shafts
SAE 4340 Steel Specification: Typical Chemical Properties (%)
| Carbon | 0.38/0.43 | Sulfur | 0.025 max. | Molybdenum | 0.20/0.30 |
| Manganese | 0.65/0.85 | Silicon | 0.15/0.35 | Nickel | 1.65/2.00 |
| Phosphorus | 0.025 max. | Chromium | 0.70/0.90 | Copper | 0.35 max. |