2024 vs 7075 Aluminum
2024 and 7075 are the two classic aerospace aluminums, and both are heat-treatable alloys that cannot be fusion welded. 2024 is a copper-magnesium alloy (2xxx series) used mostly in the naturally aged T3 and T351 tempers; 7075 is a zinc-magnesium-copper alloy (7xxx) used in the artificially aged T6 and T73 tempers. 7075-T6 has about 45% more yield strength, 503 against 345 MPa. 2024-T3 is more ductile and more damage tolerant: fatigue cracks grow more slowly and it has higher fracture toughness, which is why pressurized fuselage skins and lower wing skins are 2024 while upper wing skins and heavily loaded fittings are 7075.
Outside aircraft structure the choice is usually 7075: it is stronger, machines to a better finish and is easier to find in plate. Pick 2024 when the drawing calls for it, when the part is tension-loaded and fatigue-critical, or when sheet must be formed in a soft temper. Both corrode more readily than 6061, so both are normally bought Alclad, anodized, or chem-filmed and primed.
| Property | 2024-T3 | 7075-T6 |
|---|---|---|
| Alloy family | 2xxx (Al-Cu-Mg) | 7xxx (Al-Zn-Mg-Cu) |
| Main alloying | 3.8-4.9% Cu, 1.2-1.8% Mg, 0.3-0.9% Mn | 5.1-6.1% Zn, 2.1-2.9% Mg, 1.2-2.0% Cu |
| Tensile | 483 MPa (70 ksi), T3 | 572 MPa (83 ksi), T6 |
| Yield | 345 MPa (50 ksi), T3 | 503 MPa (73 ksi), T6 |
| Elongation | ~18% (T3 sheet) | ~11% (T6) |
| Hardness | ~120 HB | ~150 HB |
| Density | 2.78 g/cm³ | 2.81 g/cm³ |
| Fatigue crack growth and toughness | Better; the damage-tolerant choice | Lower; more notch-sensitive |
| Corrosion resistance | Poor; usually Alclad or coated | Fair; T6 prone to stress corrosion, T73 resists it |
| Typical uses | Fuselage skins, lower wing skins, rivets, fittings, screw-machine parts | Upper wing skins, spars, fittings, gears, mold plates, bike parts |
Typical values for the stated conditions. Confirm against the mill certificate and your spec.
Need a 2024-T3 or 7075-T6 part made?
- Welding & Fabrication companies that work with aluminum · 593
- Machine shops that work with aluminum · 572
- Finishing & Heat Treating companies that work with aluminum · 546
- All U.S. manufacturers working with aluminum · 2,300
- Find aluminum suppliers
Decision matrix
A check marks the side with the edge on that dimension.
| Dimension | 2024-T3 | 7075-T6 |
|---|---|---|
| Machining | Good; T351 plate and bar machine cleanly, a little gummier than T6 | ✓ Excellent; hard temper, short chips, fine finish |
| Welding | Poor; arc welds hot crack, so rivet, bolt or friction stir weld | Poor; arc welds hot crack, so rivet, bolt or friction stir weld |
| Forming | ✓ Fair in T3; good in O or freshly quenched (W), then aged | Poor in T6; form in O, then heat treat |
| Strength | 345 MPa yield (T3); slower fatigue crack growth | ✓ 503 MPa yield (T6); higher static and compressive strength |
| Corrosion resistance | Poor; the copper makes it the least resistant common alloy | ✓ Fair; better in general corrosion, specify T73 against stress corrosion |
| Finishing | Chem film and primer standard; anodizes, hardcoat harder to control | ✓ Anodizes and hardcoats reliably; darker than 6061 |
| Material cost | About 1.5-2x 6061 per pound | About 1.5-2x 6061 per pound |
| Availability | Sheet (bare and Alclad), plate and bar through aerospace distributors | ✓ Plate and bar in most metal service centers |
Choose 2024-T3 when
- Tension-loaded, fatigue-critical structure where slow crack growth matters: fuselage skins, lower wing skins, some fittings
- Sheet that must be formed, stretched or joggled in O or freshly quenched, then aged
- Parts that run warm, roughly 100-150 °C, where 2xxx alloys in T81 or T851 hold strength better than 7075
- Repair and legacy aircraft work where the drawing calls out 2024-T3 or 2024-T351
Choose 7075-T6 when
- Maximum static strength per pound: upper wing skins, spars, bulkheads, highly loaded brackets
- Machined plate parts that need a hard temper and a fine finish, such as mold plates and fixtures
- Commercial high-strength parts: bicycle and climbing hardware, firearm receivers, gears
- Use T73 or T7351 wherever stress-corrosion cracking is a risk, at about 10-15% lower strength
Frequently asked questions
- Is 2024 stronger than 7075?
- No. In their usual tempers 7075-T6 has about 503 MPa (73 ksi) yield against 345 MPa (50 ksi) for 2024-T3. 2024 gains strength in the T8 tempers, about 450 MPa (65 ksi) yield in T851 plate, but still sits below 7075-T6. Its advantage is fatigue crack growth resistance and fracture toughness, not static strength.
- Can 2024 aluminum be welded?
- Not by conventional arc welding. Like 7075, it hot cracks in the weld and the heat-affected zone loses most of its strength. Aircraft structure in 2024 is riveted or bolted. Friction stir welding and resistance spot welding work on both alloys where the joint design allows.
- Why is 2024 used for aircraft skins instead of 7075?
- Because fuselage skins are loaded in tension and cycled on every flight, and 2024-T3 grows fatigue cracks more slowly and tolerates a longer crack before it fails. Upper wing skins are loaded mainly in compression, where 7075 and its successors win on strength.
- Does 2024 aluminum corrode?
- Yes, more readily than any other common aluminum alloy, because of its roughly 4% copper. Sheet is usually bought Alclad, with a thin layer of high-purity aluminum rolled onto each face, and bare parts get a conversion coating and primer. 7075 is somewhat better in general corrosion but needs the T73 temper where stress corrosion is a risk.
