Aluminum Use in Aircraft | HARBOR Aluminum

Aircraft-Grade Aluminum Explained: Aluminum Use in Aircraft

The most high-profile use of aluminum is in the aerospace industry, where aluminum alloys are required for multiple aircraft components. Aircraft engineering has come a long way, and with the continuous research and advancements of aluminum and its alloys, the metal has become the most stable and reliable solution for the aerospace industry.

Aluminum used in aircraft is quite different from other forms found in daily items like utensils, vehicles and construction materials. This guide explains aircraft-grade aluminum and how it’s used in aircraft.

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What Is Aircraft-Grade Aluminum?

Aircraft-grade aluminum is any of the high-performance aluminum alloys fit for aircraft use. Modern aircraft comprise up to 80% of these alloys, allowing them to meet strict performance requirements. Aircraft materials must demonstrate excellent strength, durability and fatigue resistance while being considerably light. These features are only possible with aluminum alloys, which are processed through various technologies to meet the required safety and performance demands.

Why Do Planes Use Aluminum?

Aluminum is used in planes because of the unique benefits that make it the ideal construction material. Here are the benefits of aluminum that make it useful and indispensable in aircraft manufacturing:

Weight-to-Strength Ratio

Aluminum has one of the highest weight-to-strength ratios. High-performance alloys designed for aircraft parts like airframes have the strength and durability of steel and can withstand high-stress environments and processes like takeoffs and landings. At the same time, the alloys are much lighter than steel and other metals of similar strength.

Corrosion Resistance

Due to its protective oxide layer, aluminum is naturally resistant to corrosion. Its capacity to withstand extreme environments makes it the ideal material for building airplanes that are constantly exposed to the elements and severe weather conditions. Since these environments have varying degrees of corrosive elements, aluminum is the perfect corrosion-resistant solution.

Malleability

Aluminum is highly malleable and machinable. Due to calculated processes and alloy chemical composition, aircraft aluminum alloys achieve excellent formability, making them easier to cut and mold to precision than many other metals. This feature makes fabricating aluminum into complex components possible and cost-efficient for maximum aerodynamics.

Cost-Efficiency

Many features of aircraft-grade aluminum, such as low density, corrosion resistance and high thermal conductivity, make the metal far more cost-effective to produce than alternatives. The high weight-to-strength ratio alone makes aluminum fuel-efficient and economical for aircraft manufacture. While titanium boasts the highest weight-to-strength ratio of all metals, aluminum is cheaper and readily available.

Different Ways Aluminum Is Used in Aircraft

When looking at a typical plane, it’s easy to tell that most of it is aluminum because the metal makes up the entire fuselage skin. It’s also one of the main materials used for the airframe. However, its use in planes transcends the outer fuselage — here are other aluminum applications in aircraft manufacturing:

Wing skin: Aluminum is a critical component in wings. It’s used in the upper and lower wing skins to provide enhanced strength, fatigue resistance and better damage tolerance. Additionally, aluminum is used for vertical and horizontal stabilizers and wing stringers due to its lightweight and high-strength features.
Engine: High-performance aluminum alloys are used to manufacture engine components such as pistons and compressor blades. Besides titanium, these alloys are a common alternative due to their durability and heat tolerance with working temperatures of up to 300°C.
Fuel tank: Aluminum is commonly used in aircraft fuel tanks due to its corrosion resistance and lightweight features. Treated alloys offer better performance compared to steel.
Heat exchanger: Aluminum is the most common material in heat exchangers due to its great thermal conductivity and lightweight characteristics.
Interior fixtures: Metal fixtures inside the aircraft are generally made of aluminum, which is crucial for keeping the weight down. These interior parts include cabin walls, seats, doors, overhead bins and similar.

Common Types of Aluminum Alloys Used in Aircraft

The aerospace industry employs advanced aluminum alloys classified into four-digit groups identified by the first digit, which stands for the alloy group. Some common alloys used in aircraft manufacturing belong to the 7xxx series, 2xxx series and Al-Li alloy categories.

The 7xxx Series Aluminum Alloys

Some of the most useful aerospace aluminum alloys belong to the 7xxx series, which contains zinc as the primary alloy. With the addition of other elements like magnesium and copper, the alloys in the series demonstrate superior strength, with applications in aircraft shafts, gears, fittings and more.

Common 7xxx alloys used in aircraft include:

Alloy 7050: This alloy is one of the most preferred in the aerospace industry due to its durability and excellent corrosion resistance, which increases damage tolerance.
Alloy 7075: This alloy boasts increased strength that matches many types of steel, which makes it ideal for aircraft components subjected to high-stress conditions.
Alloy 7068: This alloy is one of the strongest in the industry, with additional lightweight and corrosion-resistant features. It’s mostly reserved for applications where extreme strength is necessary. Common subtypes include 7068-T6 and 7068-T6511.

The 2xxx Series Aluminum Alloys

The 2xxx series contains copper as the primary alloy material. These alloys have high strength and damage tolerance. They also often contain magnesium, which increases their strength, damage tolerance and fatigue resistance.

Common 2xxx alloys used in aircraft include:

Alloy 2014: These are high-strength alloys with good machinability. Common subtypes are 2014-T6 and 2014-T651.
Alloy 2024: These alloys are well-known for their high strength, which makes them ideal for wing and fuselage components. Some of the 2024 alloys with common applications are 2024-T3 and 2024-T851.
Alloy 2219: When heat treated, these alloys possess high elasticity, temperature resistance and corrosion resistance. Common subtypes are 2219-T62 and 2219-T87.

The Al-Li Alloys

Al-Li alloys are popular materials with aerospace and military applications. They contain lithium as the main alloy ingredient in various degrees, which improves aluminum’s lightweight characteristics. With the addition of other elements, Al-Li alloys can possess more advantages, such as increased toughness, tensile strength and corrosion resistance.

Common Al-Li alloys used in aircraft include:

Alloy 2050: This highly ductile alloy is designed to replace various alloys like the 2024 and 7150. It has excellent properties such as corrosion resistance, strength, low weight, energy absorption and machinability.
Alloy 2090: This heat-treatable wrought alloy has high strength and formability properties. It’s used for components like leading and trailing edges and fuselage bulkhead webs.
Alloy 2198: This is a low-density alloy with balanced properties, such as high strength, fracture toughness and fatigue resistance.

Understand the Aluminum Market With HARBOR Aluminum

Aluminum in the aerospace industry is the key element in the manufacturing of aircraft components and other systems. Considering that metal comprises the bulk of aircraft, from the fuselage to internal parts, it makes sense to stay updated with market insight as a strategy to inform your use of aluminum in the aerospace industry. With the knowledge and accurate data on aluminum market trends and price outlook, you can create a robust business and budgeting strategy. As the authority in aluminum, HARBOR offers the most reliable and in-depth insight to help you navigate the global aluminum market. Subscribe to HARBOR Aluminum’s market intelligence reports to make strategic decisions and gain a competitive edge!

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