The 2000 series aluminum alloys contain copper to increase strength, and 2024 is often specified for aerospace and some motorsport applications because of its high specific strength.
2024 aluminum is around 90 – 95% pure and contains 3.8–4.9% copper, 1.2–1.8% magnesium, and small amounts of other elements. The T351 temper, which involves a solution heat treatment, followed by a 1 to 3% stretch and aging, creates copper-magnesium precipitates that raise strength and fatigue resistance.
Yield strength is comparable to 1020 steel, but its density is about one-third. Accordingly, the high specific strength of 2024-T351 aluminum makes it a popular choice in a wide range of aircraft applications, especially for airframe components.
Although 2024 aluminum has poor corrosion resistance, this can be addressed by cladding the surface with a thin layer of pure aluminum (Alclad). Anodizing is also possible, although it requires careful process control to achieve durable results.
2024-T351 aluminum is known for its good machining properties. Like 6061 aluminum, it cuts readily, but it forms small chips rather than strings. The stress-relieving properties of the T351 temper further improve machinability. Stretching lowers residual stress, which minimizes distortion after metal removal. The benefits are especially pronounced in thicker sections and in parts with complex, asymmetric geometries.
2024-T351 can be cold worked as the heat treatment leaves the alloy with good ductility. However, welding is not recommended as the heat can create cracking and reduces the strength-raising benefits of the T351 temper.
| Property | Value | Notes |
|---|---|---|
| Material Type | 2000 series aluminum (copper-alloyed) | UNS A92024 |
| Density | 2.78 g/cm3 | 0.10 lb/in3 |
| Melting Point | ~502-638 °C | ~935-1,180 °F |
| Hardness (Brinell) | ~120 | |
| Tensile Strength | ~469 MPa | ~68,000 psi |
| Yield Strength | ~324 MPa | ~47,000 psi |
| Elongation at Break | ~ 9-20 % | |
| Modulus of Elasticity | ~73.1 GPa | ~10.6 x106 psi |
| Corrosion Resistance | Poor | 2024-T351 is typically anodized or given an aluminum cladding (Alclad) |
| Magnetism | No | |
| Heat Treatment | T351 temper | Entails solution aging, stretching, and aging |
| Machinability | Good | Similar to 6061 but creates short chips rather than strings |
| Weldability | GMAW should not be used. Hot cracking and loss of strength are likely | Friction stir welding is possible |
| DFARS Compliance | No | Not qualified as a specialty steel under DFARS |
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