Aluminium 2024 (UNS A92024) is legendary within the metallurgical industry as the foundational "Aircraft Alloy." By heavily alloying the aluminium matrix with 3.8% to 4.9% Copper (Cu), along with critical additions of Magnesium and Manganese, and subjecting it to precise solution heat-treatment (T3 or T4 tempers), the metal undergoes dramatic precipitation hardening. This transforms it into a high-strength fastener capable of matching the tensile yield of many low-carbon steels, while weighing nearly 70% less.
While 2024 boasts an elite strength-to-weight ratio and absolutely phenomenal high-cycle fatigue resistance, it comes with a known engineering trade-off: poor corrosion resistance. The heavy copper content makes it susceptible to galvanic and intergranular corrosion in harsh environments. Therefore, Aluminium 2024 fasteners are almost exclusively utilized in their anodized form, or coated with aerospace-grade cadmium or zinc-nickel plating, making them the ultimate lightweight structural hardware for commercial aviation, military airframes, and professional motorsports.
| Material Classification | Heat-Treatable Copper-Aluminium Alloy (Aerospace Grade) |
|---|---|
| UNS Designation | A92024 |
| Microstructure | FCC Matrix with Cu-Mg Precipitation Strengthening |
| Magnetic State | Completely Non-Magnetic |
| Density | 2.78 g/cm³ (0.100 lb/in³) |
| Size Range | Metric: M3 to M36 | Imperial: #4 to 1-1/2" |
| Primary Attribute | Elite Strength-to-Weight Ratio & High-Cycle Fatigue Life |
Contains detailed high-cycle fatigue (S-N curve) limits for cyclic loading, MIL-A-8625 Type III Hardcoat Anodizing thread tolerance adjustments, and aerospace cold-heading constraints.
⬇ DOWNLOAD DATASHEETIn aerospace and high-stress automotive applications, fastener failure leads to catastrophic structural loss. Verification of the exact T4 or T351 thermal heat-treatment temper is absolutely mandatory to guarantee the alloy reached its targeted tensile strength. Ananka guarantees full aerospace traceability.
The strength of 2024 is derived from its complex, multi-element matrix. Copper is the primary precipitation hardener. Magnesium significantly increases the alloy's response to heat treatment, while Manganese acts as a grain-refiner, drastically improving the metal's impact toughness and resistance to cyclic fatigue.
| Aluminium (Al) | Copper (Cu) | Magnesium (Mg) | Manganese (Mn) | Iron (Fe) | Silicon (Si) |
|---|---|---|---|---|---|
| Balance (~93.5) | 3.80 – 4.90 | 1.20 – 1.80 | 0.30 – 0.90 | 0.50 Max | 0.50 Max |
| Mechanical Property | Typical Limits (T3 / T4 Heat-Treated Temper) |
|---|---|
| Tensile Strength | 60,000 - 68,000 psi (415 - 470 MPa) |
| Yield Strength | 40,000 - 47,000 psi (275 - 325 MPa) |
| Fatigue Strength (500 million cycles) | 20,000 psi (~138 MPa) |
| Hardness (Brinell) | 120 HB |
| Standard / System | Designation |
|---|---|
| ASTM Specifications | ASTM B211 (Bar, Rod, Wire), ASTM F468 (Fasteners) |
| Common Trade Names | 2024-T4, Aircraft Alloy, Duralumin (Historic) |
| European Equivalent | EN AW-2024 / AlCu4Mg1 (DIN 3.1355) |
| Military / Aerospace | AMS 4120, QQ-A-225/6 |
| Mating Bolts/Studs | Internal Threads (Nuts) | Washers |
|---|---|---|
| 2024-T4 Hex Bolts & Socket Caps | 2024-T4 Precision Hex Nuts | 2024-T4 or 7075-T6 Flat Washers |
Aluminium 2024 is significantly stronger than pure 1100 or standard 6061 aluminium, allowing it to withstand much higher torque limits. However, in aerospace applications, galling between aluminium threads under load is a serious concern. Aerospace-grade dialectric anti-seize or dry-film lubricants (Moly) are highly recommended.
| Nominal Diameter | Threads Per Inch (UNC) | Max Target Torque (in-lbs) | Max Target Torque (ft-lbs) |
|---|---|---|---|
| 1/4" | 20 | 65 - 75 | ~ 6.0 |
| 5/16" | 18 | 120 - 130 | ~ 10.5 |
| 3/8" | 16 | 200 - 220 | ~ 17.5 |
| 1/2" | 13 | 400 - 450 | ~ 35.0 |
While Aluminium 7075 (alloyed with Zinc) has a higher ultimate tensile strength and yield point than 2024, it is more brittle. Aluminium 2024 possesses vastly superior high-cycle fatigue resistance and better fracture toughness. In an airplane wing that constantly flexes and vibrates millions of times over its lifespan, the fatigue resistance of 2024 prevents catastrophic crack propagation better than 7075.
The element that gives 2024 its incredible strength—Copper—is highly cathodic to Aluminium. On a microscopic level, when moisture (an electrolyte) hits the raw metal, galvanic micro-cells form between the copper precipitates and the aluminium matrix, causing the aluminium to sacrifice itself and corrode rapidly. To prevent this, 2024 fasteners are almost universally hard-coat anodized or plated with a sacrificial coating before installation.
No. Aluminium 2024 is widely considered unweldable. The heat from a TIG or MIG torch destroys the careful T4 heat-treatment temper, ruining the metal's strength. More importantly, the high copper content makes the weld pool highly susceptible to "hot cracking" as it cools. 2024 components must be joined exclusively via mechanical fasteners (like 2024 bolts or rivets).
