What Grade of Aluminium Is Used in Aircraft?

Aluminium is one of the most essential materials in modern aerospace engineering. Its unique combination of low weight, high strength, corrosion resistance, and ease of fabrication has made it the backbone of aircraft structures for more than a century. From the early days of aviation to the development of advanced commercial jets and spacecraft, aluminium alloys have played a crucial role in shaping the aerospace industry.

But many people often ask: What grade of aluminium is used in aircraft? The answer is not limited to a single alloy. Aircraft construction uses several specialized aluminium grades, each chosen for specific components and performance requirements. In this article, we will explore the most commonly used aluminium grades in aviation, their properties, and the reasons they dominate this high-technology sector.

As a leading global manufacturer and supplier of aerospace-grade aluminium materials, SASAALUMINUM provides a detailed look into how these alloys contribute to strength, safety, and efficiency in modern aircraft.

1. Why Aluminium Is Essential in Aircraft Construction

Aluminium remains the preferred metal in aircraft manufacturing due to its unique balance of strength, weight, and durability. These characteristics are vital for flight, where every kilogram affects fuel efficiency and performance.

Key Advantages:

• Lightweight: About one-third the density of steel, reducing overall aircraft mass.

• High Strength-to-Weight Ratio: Provides structural integrity without excess weight.

• Corrosion Resistance: Natural oxide layer protects against moisture and oxidation.

• Ease of Fabrication: Can be machined, extruded, rolled, or formed into complex shapes.

• Recyclability: Fully recyclable, supporting sustainability in aerospace production.

These benefits make aluminium the ideal material for fuselage frames, wings, landing gear, and engine components where precision and reliability are paramount.

2. Overview of Aluminium Grades Used in Aircraft

Aircraft manufacturing does not use pure aluminium, as it is too soft for structural applications. Instead, engineers use high-strength aluminium alloys that include copper, magnesium, manganese, silicon, and zinc.

The most commonly used series in aerospace applications are the 2xxx, 6xxx, and 7xxx series of wrought aluminium alloys, each with unique advantages for different components of an aircraft.

3. The 2xxx Series: Aluminium-Copper Alloys

Example Grades: 2024, 2014, 2017

The 2xxx series aluminium alloys are primarily alloyed with copper, which provides excellent strength and fatigue resistance. They are typically used in high-stress applications such as fuselage skins, wing tension members, and landing gear components.

Typical Composition (2024 Alloy):

• Copper (Cu): 3.8–4.9%

• Magnesium (Mg): 1.2–1.8%

• Manganese (Mn): 0.3–0.9%

• Aluminium (Al): Balance

Key Features:

• High strength comparable to some steels.

• Good fatigue resistance for repetitive stress conditions.

• Excellent machinability.

Limitations:

• Lower corrosion resistance than other series; often requires cladding or surface treatment.

Applications: Aircraft fuselage skins, wing ribs, bulkheads, and structural reinforcements.

Fun Fact: The 2024-T3 alloy was one of the earliest materials used in aircraft like the Douglas DC-3 and remains a standard today for its proven reliability.

4. The 6xxx Series: Aluminium-Magnesium-Silicon Alloys

Example Grades: 6061, 6063, 6082

The 6xxx series aluminium alloys are versatile and known for their excellent corrosion resistance, moderate strength, and weldability. While not as strong as 2xxx or 7xxx series alloys, they are widely used for non-critical aircraft parts and internal structures.

Typical Composition (6061 Alloy):

• Magnesium (Mg): 0.8–1.2%

• Silicon (Si): 0.4–0.8%

• Copper (Cu): 0.15–0.4%

• Chromium (Cr): 0.04–0.35%

Key Features:

• Balanced strength and corrosion resistance.

• Excellent workability and surface finish.

• Good weldability and formability.

Applications:

• Aircraft fittings, hydraulic pipes, fuel lines, and small structural components.

• Used in general aviation, support structures, and lightweight assemblies.

6061-T6 remains a go-to alloy for modern aircraft interiors, tooling fixtures, and mechanical components because of its versatility and cost-effectiveness.

5. The 7xxx Series: Aluminium-Zinc-Magnesium-Copper Alloys

Example Grades: 7075, 7050, 7475

The 7xxx series alloys are the strongest aluminium grades used in aerospace engineering. With zinc as the main alloying element, they achieve extremely high tensile strength and fatigue resistance, comparable to high-grade steel—but at one-third the weight.

Typical Composition (7075 Alloy):

• Zinc (Zn): 5.6–6.1%

• Magnesium (Mg): 2.1–2.5%

• Copper (Cu): 1.2–1.6%

• Chromium (Cr): 0.18–0.28%

Key Features:

• Very high strength-to-weight ratio.

• Excellent toughness and fatigue performance.

• Used in critical, high-stress components.

Limitations:

• Less corrosion resistant than 5xxx or 6xxx series; requires protective coatings or anodizing.

Applications:

• Aircraft wing spars, landing gear, fuselage frames, and structural bolts.

7075-T6, often referred to as the “aircraft alloy,” is one of the most famous aerospace materials in history. It was first developed for the Japanese Zero fighter aircraft during World War II and is still used in advanced aircraft and spacecraft designs today.

6. The 5xxx Series: Aluminium-Magnesium Alloys

Example Grades: 5052, 5083, 5A06

The 5xxx series alloys are non-heat-treatable but offer excellent corrosion resistance and weldability. While not as strong as 2xxx or 7xxx alloys, they are widely used for components exposed to marine or chemical environments.

Typical Composition (5083 Alloy):

• Magnesium (Mg): 4.0–4.9%

• Manganese (Mn): 0.4–1.0%

• Chromium (Cr): 0.05–0.25%

Key Features:

• High corrosion resistance in seawater and industrial environments.

• Excellent weldability and toughness.

• Maintains strength at low temperatures.

Applications:

• Fuel tanks, marine aircraft hulls, pressure vessels, and floor panels.

SASAALUMINUM manufactures 5xxx series sheets and plates for aircraft structures that demand both lightweight and corrosion-resistant performance.

7. The 1xxx and 3xxx Series: For Non-Structural Uses

Although the 1xxx (pure aluminium) and 3xxx (aluminium-manganese) series are not used in primary load-bearing structures, they serve essential secondary roles.

• 1xxx series (e.g., 1100): Used for decorative panels, nameplates, and low-strength fittings due to excellent corrosion resistance and formability.

• 3xxx series (e.g., 3003): Used in heat exchangers, fuel systems, and ductwork because of its superior workability and moderate strength.

These alloys complement the structural grades by supporting lightweight, corrosion-free performance for auxiliary aircraft systems.

8. Key Aluminium Tempers in Aircraft

The mechanical properties of aluminium alloys depend heavily on their temper, which indicates the type of heat treatment or mechanical work applied.