4340 alloy steel bar is used heavily in the aerospace industry due to its ultra-high strength. When heat treated it is known for its toughness while preserving good fatigue strength. For highly stressed parts it is an excellent choice. It can be machined by all customary methods. This material is available in both vacuum melt (VM) and air melt (AM).
We sell our trademark material Durelloy that is made to last and perform better than standard 4340.
| Minimum Properties | Tensile Strength, psi | 140,000 |
| Yield Strength, psi | 120,000 | |
| Elongation | 14% | |
| Rockwell Hardness | Rc 32/39 | |
| Chemistry | Carbon(C) | .38 -.43% |
| Chrome (Cr) | 0.70- 0.90% | |
| Manganese (Mn) | 0.60-0.80% | |
| Molybdenum (Mo) | 0.20 – .30% | |
| Nickel (Ni) | 1.65-2.0% | |
| Phosphorus (P) | 0.030% | |
| Sulphur (S) | 0.040% | |
| Silicon (Si) | 0.15- 0.35% |