2024-T3 Aluminum Alloy: Aerospace Structural Grade — Properties & Applications

AMS 4037 / ASTM B209 · Published: 2026-06-01 · Updated: 2026-06-02

2024-T3 is the most widely used high-strength aluminum alloy in aerospace structures, valued for its exceptional fatigue crack growth resistance and high fracture toughness. The aluminum-copper-magnesium system (Al-Cu-Mg, 4.4% Cu, 1.5% Mg, 0.6% Mn) achieves strength through natural aging (T3 temper: solution heat treated, cold worked, and naturally aged to a stable condition) and precipitation hardening by Guinier-Preston-Bagaryatsky (GPB) zones and S-phase (Al2CuMg) precipitates. The cold work (~2-3% stretch) after solution treatment relieves residual stresses and accelerates natural aging. T3 temper is the standard for sheet and plate products; T351 is the stress-relieved variant for plate >12.7mm thickness.

2024-T3 is the fuselage skin material of choice for Boeing 737, 777, and Airbus A320 families — the alloy's fatigue crack growth rate (da/dN at ΔK = 20 MPa√m) is approximately 2× slower than 7075-T6, meaning cracks propagate more slowly and are more likely to be detected during routine inspections. The trade-off: 2024-T3 has approximately 40% lower yield strength than 7075-T6 (345 MPa vs 503 MPa). Corrosion note: 2024 is copper-rich and has poor general corrosion resistance — it must be clad with commercially pure aluminum (Alclad 1230 or 1050) for exterior aerospace applications. The cladding provides galvanic protection (the clad corrodes instead of the structural 2024 core).

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