What is AISI4340?
AISI4340 steel is an AISI/SAE standard alloy steel with nickel chromium molybdenum. This comprehensive guide covers chemical composition, mechanical properties, and machining characteristics per AISI/SAE standards.
Chemical Composition
| Element | Content (%) | Standard |
|---|---|---|
| C | 0.37-0.45 | ASTM/GB |
| Mn | 0.50-0.80 | ASTM/GB |
| P | ≤0.035 | ASTM/GB |
| S | ≤0.035 | ASTM/GB |
| Si | 0.17-0.37 | ASTM/GB |
| Fe | Balance | ASTM/GB |
Mechanical Properties
| Property | Value | Standard |
|---|---|---|
| Tensile Strength | ≥850 MPa | AISI/SAE |
| Yield Strength | ≥670 MPa | AISI/SAE |
| Elongation | ≥9% | AISI/SAE |
| Hardness | 275 HV | HV |
| Density | 7.85 g/cm³ | 20°C |
Key Features
- High strength and toughness
- Good hardenability
- Suitable for heat treatment
- Good machinability in annealed condition
- Widely used in automotive and aerospace
Applications
- Automotive components
- Aerospace parts
- High-strength structural parts
- Gear and shaft components
Machinability
AISI4340 steel has good machinability. Recommended: Carbide tools, cutting speed 80-150 m/min, feed 0.15-0.30 mm/rev.
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