4340M steel which is modified from AISI 4340 Steel,also known as 300M.
| Grade | C | Si | Mn | Cr | Ni | Mo | V |
| 4340 | 0.38-0.43 | 0.15-0.35 | 0.6-0.9 | 0.7-0.9 | 1.65-2.0 | 0.2-0.3 | / |
| 4340M | 0.38-0.43 | 1.45-1.80 | 0.6-0.9 | 0.7-0.9 | 1.65-2.0 | 0.3-0.5 | 0.05-0.1 |
As a low-alloy ultra-high-strength steel, 4340M steel, after quenching and tempering, can achieve a tensile strength exceeding 1860 MPa.
Mechanical Performance Characteristics
- High Strength
- High Lateral Plasticity
- High Fracture Toughness
- Excellent Fatigue Performance
- Good Corrosion Resistance
These properties are extremely beneficial for the long-term use of aircraft landing gear and other aircraft components, which is the main reason for the widespread application of 4340M steel in the aircraft industry.