2024 T3 Aluminum Alloy
High-strength wrought aluminum-copper alloy (2024) in T3 temper – solution heat-treated, cold-worked, and naturally aged. Primarily used in aerospace structural components, high-performance automotive parts, and demanding mechanical assemblies where weight-to-strength ratio is critical.
Material Overview & Common Uses
2024 T3 is a heat-treatable aluminum alloy with copper (4.3–4.5%) as the primary alloying element, plus magnesium (1.3–1.5%) and manganese (0.5–0.6%). The T3 temper involves solution heat treatment at 495±5°C, rapid water quench, cold working (typically 1.5–2.5% stretch), and natural aging at room temperature for at least 96 hours. This yields a tensile strength of 470 MPa and yield strength of 325 MPa, making it one of the strongest aluminum alloys without compromising moderate ductility. Common uses: aircraft wing skins, fuselage frames, military vehicle armor, high-performance bicycle frames, and structural extrusions for aerospace jigs. Not recommended for welding without post-weld heat treatment due to stress corrosion cracking susceptibility.
Core Technical Properties & Sizing
| Property | Value / Specification |
|---|---|
| Ultimate Tensile Strength (UTS) | 470 MPa (min) per AMS 4037 |
| Yield Strength (0.2% offset) | 325 MPa (min) |
| Elongation in 50 mm | 10% (min) for thickness ≤ 6.3 mm; 8% for > 6.3 mm |
| Shear Strength | 285 MPa (typical) |
| Brinell Hardness (HB 500/10) | 120–140 |
| Modulus of Elasticity | 73.1 GPa |
| Density | 2.78 g/cm³ |
| Thermal Conductivity (25°C) | 121 W/m·K |
| Electrical Conductivity (% IACS) | 30% (annealed); 23% (T3) |
| Available Sizes (thickness) | 0.3 mm – 150 mm (sheet, plate); extrusions up to 300 mm width |
| Standard Lengths | 72″–144″ (sheet), 96″–240″ (plate) |
Machinability, Tooling & Feeds
2024 T3 has good machinability, rated as a 70% machinability index relative to free-machining brass. The material produces short, well-broken chips under most conditions; however, the high copper content can cause built-up edge at lower speeds. Carbide tooling is standard; high-speed steel is acceptable for low-volume runs. Use positive rake angles and sharp inserts to minimize work hardening. Coolant: water-soluble oil or straight mineral oil with high lubricity. For drilling, use 118°–135° split-point drills and peck cycles when hole depth exceeds 3× diameter.
Recommended Parameters
| Operation | Cutting Speed (m/min) | Feed (mm/rev) | Depth of Cut (mm) |
|---|---|---|---|
| Turning (Carbide insert) | 450–700 | 0.20–0.40 | 1.0–4.0 |
| Face Milling (Carbide) | 500–750 | 0.10–0.30 (per tooth) | 0.5–3.0 |
| Drilling (HSS, Ø6–12 mm) | 40–60 | 0.08–0.15 | — |
| Reaming (Carbide) | 30–50 | 0.10–0.20 | 0.2–0.5 (allowance) |
| Tapping (HSS, M6–M12) | 5–10 | 1.0 (pitch) | — |
Note: Use climb milling where possible; reduce speed by 20% for high-cobalt HSS. For thin-walled parts (< 1 mm), reduce feeds by 50% and apply rigid clamping.
Common Defects & Quality Control
| Defect | Description | QC Method / Rejection Criterion |
|---|---|---|
| Exfoliation Corrosion | Intergranular corrosion along elongated grain structure, visible as layered flaking. | ASTM G34 exfoliation test (visual rating ≥ EB unacceptable). Reject if surface blistering or layer separation exceeds 0.1 mm depth. |
| Stress Corrosion Cracking (SCC) | Cracking under sustained tensile stress in corrosive environments, especially in short transverse direction. | Alternate immersion test per ASTM G47. Reject if any crack ≥ 1.5 mm appears within 90 days. |
| Inclusions / Porosity | Non-metallic particles or gas voids visible on machined surfaces or in radiographic inspection. | Fluorescent penetrant (ASTM E1417) or X-ray per ASTM E155. Reject if inclusion length > 1.0 mm or cluster density > 5 per 25 cm². |
| Surface Laps / Seams | Folds or overlapping material from rolling or extrusion process; often longitudinal. | Visual + Eddy current per ASTM E309. Reject if depth exceeds 0.1 mm or length > 6 mm. |
| Microstructural Banding | Elongated grain structure due to insufficient recrystallization; reduces fatigue life. | Metallographic examination per ASTM E3. Reject if grain aspect ratio > 4:1 in short transverse. |
Storage, Handling & Racking Guidelines
2024 T3 requires careful storage to prevent corrosion and mechanical damage. Store indoors in controlled humidity (< 50% RH). Do not store in the same area as copper, brass, or stainless steel without isolating to avoid galvanic corrosion. Use wooden or plastic dunnage to separate layers; never stack directly on concrete floors. For long-term storage ( > 6 months), apply a protective oil coating or VCI paper. In-process handling: wear clean gloves to avoid acid transfer from fingerprints – clean with isopropyl alcohol if needed. For racking, ensure edge supports no more than 600 mm apart for sheet stock to prevent sagging; for plate, use vertical racking with padded cradles.
Recommended Storage Conditions
| Parameter | Specification |
|---|---|
| Storage Temperature | 15–30 °C |
| Maximum Relative Humidity | 50% (non-condensing) |
| Maximum Stack Height (sheet) | 900 mm (with 50×50 mm wooden spacers between layers) |
| Inspection Interval | Quarterly – visual check for corrosion, edge damage, and flatness (max deviation 1 mm/600 mm) |
| SupplyGrid Reorder Point | When stock falls below 2 weeks of average consumption for critical sizes. Use kanban card to trigger auto-PO. |