Aluminum 2024-T3 is a aluminum alloy used in aerospace applications. Melting point: 502 °C. Tensile strength: 483 MPa.
If you have ever flown on an airliner, you have trusted your life to a thin metal skin made of aluminum 2024-T3. This copper-strengthened alloy is one of the most important structural materials in the history of flight and spaceflight.
Quick facts
- Type: 2000-series aluminum alloy (an alloy is a metal blended with other elements), where copper is the main added ingredient. Its older name was “24ST.”
- Main ingredients: aluminum (about 91-95% by weight) plus copper (3.8-4.9%), magnesium (1.2-1.8%), and manganese (0.3-0.9%).
- Density: about 2.78 grams per cubic centimeter (0.10 pounds per cubic inch) — very light for a structural metal.
- Strength: ultimate tensile strength (the pull it can take before snapping) is roughly 400-483 MPa (58-70 ksi); yield strength (where it starts to bend permanently) is about 270-345 MPa (39-50 ksi).
- Stiffness: Young’s modulus (resistance to stretching) is about 73 GPa.
- Hardness: Brinell hardness about 120.
- Heat limits: melting begins near 500 C (932 F); useful working range is roughly -50 C up to about 120-150 C.
What it is and how it works
The “2024” names the recipe of metals in the blend; the “T3” names the temper — the specific heat-and-stretch treatment that gives the metal its final strength. T3 is a three-step process. First, the metal is heated until the copper fully dissolves into the aluminum, then quickly cooled (“quenched”) to trap that copper in place. Second, it is stretched or rolled at room temperature (“cold work”), which introduces tiny internal line defects called dislocations that make it harder. Third, it is simply left to sit at room temperature (“natural aging”), during which microscopic copper-rich particles form on their own and lock the structure in place — no oven needed.
The payoff is a metal roughly four to five times stronger than pure aluminum at the same low weight. Even better, 2024-T3 resists fatigue: the slow forming and spreading of tiny cracks caused by the repeated load cycles a flying vehicle endures every flight. Think of bending a paperclip back and forth — most metals eventually snap from this. When a crack does start in 2024-T3, the alloy slows its growth, giving inspectors time to spot it. That quality is called damage tolerance, and it is the alloy’s superpower.
The trade-off is corrosion. The copper that makes 2024-T3 strong also makes it chemically vulnerable, especially to humid or salty air. So it is almost always sold as “Alclad 2024-T3”: thin layers of nearly pure aluminum are roll-bonded onto each face. Like a sacrificial coat of paint, those soft outer layers corrode first and protect the strong core, though cladding does slightly lower fatigue strength. The alloy also does not weld well, so parts are riveted or bolted together rather than welded.
Why it matters
2024-T3 set the standard for the modern metal airframe. Its mix of high strength, low weight, and best-in-class fatigue resistance made the all-metal, pressurized, long-life airliner practical. It is the go-to choice wherever a structure is pulled in tension — such as fuselage skins and lower wing skins. It complements 7075-T6, a zinc-based alloy chosen where higher static or compressive (crushing) strength matters more than fatigue life.
Where it is used and notable examples
- Airliner skins: essentially all modern airliners use Alclad 2024-T3 for fuselage skin. The Boeing 737, the best-selling jetliner ever, is roughly 80% aluminum by structure.
- Repairs and restoration: 2024-T3 sheet is the standard material for patching fuselage and wing skins across general and commercial aviation.
- Spacecraft and stations: the aluminum-alloy family, including 2024-class alloys, was used extensively on Apollo, Skylab, the Space Shuttle orbiters, and the International Space Station. Modern spacecraft are roughly 50-90% aluminum alloy by mass.
- Warm airframe regions: areas near engines, where temperatures reach about 120 C (248 F).
- Fatigue-critical parts generally: wing tension members and control-surface skins, where damage tolerance is the deciding factor.
Al 90.7-94.7%, Cu 3.8-4.9%, Mg 1.2-1.8%, Mn 0.3-0.9%
| DENSITY | 3 kg/m³ |
| TENSILE STRENGTH | 483 MPa |
| YIELD STRENGTH | 345 MPa |
| STRENGTH-TO-WEIGHT | 173741 kN·m/kg |
| MELTING POINT | 502 °C |
| MAX SERVICE TEMPERATURE | 175 °C |
| THERMAL CONDUCTIVITY | 121 W/m·K |
| THERMAL EXPANSION | 23.2 µm/m·K |
| CATEGORY | Aluminum Alloy |
| DESIGNATIONS | UNS A92024, AMS 4037 |
| MANUFACTURER | Alcoa / Arconic |
| DENSITY | 3 kg/m³ |
| TENSILE STRENGTH | 483 MPa |
| YIELD STRENGTH | 345 MPa |
| MELTING POINT | 502 °C |
| MAX SERVICE TEMP | 175 °C |
| THERMAL CONDUCTIVITY | 121 W/m·K |
| THERMAL EXPANSION | 23.2 µm/m·K |
| CORROSION RESISTANCE | Fair |
| WELDABILITY | Poor |
| MACHINABILITY | Good |
| COST RATING | Low |
