2024-T4 Aluminum
A 2000-series Al-Cu-Mg alloy, the fatigue-resistant aerospace alloy
Typical values for the temper in the title
2024 is a heat-treatable aluminum-copper alloy with about 4.4% copper and about 1.5% magnesium. In the T4 temper it reaches a tensile strength of 470–480 MPa, and its standout advantage is good resistance to fatigue and to crack growth.
That makes it the classic alloy for fuselage skin and lower wing surfaces, which work in cyclic tension. The price: low corrosion resistance because of the copper, so sheet is usually supplied as Alclad, and it cannot be fusion welded.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 470–480 MPa | |
| Yield strength Rp0.2 | 325–345 MPa | |
| Elongation A | 18% | |
| Hardness | 120 HB | |
| Modulus of elasticity E | 73.1 GPa | |
| Density ρ | 2.78 g/cm³ | |
| Machinability | 75% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Cu copper | 3.8–4.9 | the main element: Al-Cu-Mg precipitates give the strength |
| Mg magnesium | 1.2–1.8 | part of the strengthening precipitates |
| Mn manganese | 0.30–0.9 | controls the grain structure and adds strength |
| Si silicon | max 0.50 | |
| Fe iron | max 0.50 | |
| Zn zinc | max 0.25 | |
| Ti titanium | max 0.15 | |
| Cr chromium | max 0.10 | |
| Zr+Ti | max 0.20 | |
| Al aluminum | balance |
Common tempers
In 2024 the temper sets the balance between strength, fatigue resistance and corrosion resistance.
| Temper | Properties | When to choose it |
|---|---|---|
| T3 | solution treated, cold worked, naturally aged | the common sheet temper: fuselage skin |
| T351 | as T3, stress relieved by stretching | plate and bar for machining |
| T4 | Rm 470–480 MPa, Rp0.2 325–345 MPa | solution treated and naturally aged |
| T6 / T8x | artificially aged | higher yield and better resistance to stress corrosion cracking and heat, in some cases at the expense of ductility |
Applications
- Fuselage skin and lower wing surfaces
- Aerospace structural parts under fatigue loading
- Rivets and fasteners
- High-strength machined parts
- Wheels and structures in high-performance vehicles
Fabrication
Machining
Machines well in T3, T351 and T4: the chip breaks well and the finish is good. For precise parts, T351 is better, being stress relieved.
Welding
Fusion welding is not recommended: the alloy is prone to hot cracking, and the heat-affected zone loses strength and becomes susceptible to corrosion. Join with rivets and bolts. Friction stir welding (FSW) is possible.
Corrosion and protection
The copper lowers corrosion resistance, so protection matters. For sheet, Alclad is common: a thin layer of purer aluminum on both sides that protects it as an anode. For machined parts: conversion coating, anodizing (Type I or II) and paint.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 7075-T6 | 503–572 / 434–503 MPa | Not recommended — FSW | when higher static strength is needed and fatigue matters less · material page |
| Alclad 2024-T3 | 441 / 324 MPa | Not recommended | for exposed sheet, when corrosion resistance is critical · material page |
| 2014-T6 | 483 / 414 MPa | Not recommended | for heavy forged parts, at slightly higher strength · material page |
Common mistakes
Welding 2024
Fusion welding creates cracks and a weak, corrosion-prone zone. Join with rivets or bolts.
Leaving 2024 unprotected in a humid environment
Without protection it may suffer intergranular corrosion. A coating, anodizing or Alclad is a must.
Choosing by strength alone
7075 is stronger, but 2024 is better in fatigue and damage tolerance. For a part under cyclic loading, that can be decisive.
Equivalents, standards and supply
| EN | 3.1355 |
|---|---|
| DIN | AlCuMg2 |
| JIS | A2024 |
| Standards | ASTM B209 / AMS 2770 / EN 485-2 |
| Forms | plate · rod · extrusion |
| Producers | Alcoa · Novelis · Constellium · Kaiser |
Learn more
Values are typical and for comparison only. For design, rely on the standard and on the mill certificate. Sources: Aluminum Association (composition), ASM and MatWeb data sheets, and the METAL HUB materials database.
Updated: October 31, 2026