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The use of Aluminum Alloys in Aircraft Construction

Aluminum Alloys in Aircraft Construction

Aircraft-grade Aluminum is the core material for aircraft and aerospace vehicle manufacturing. Along with the increasing requirements for flight performance, payload, fuel consumption, service life, and safety and reliability in the design and manufacture of modern aircraft, higher and higher demands are placed on the comprehensive performance and weight reduction effect of aluminium alloy structures.

Aircraft-grade Aluminum is the core material for aircraft and aerospace vehicle manufacturing. Along with the increasing requirements for flight performance, payload, fuel consumption, service life, and safety and reliability in the design and manufacture of modern aircraft, higher and higher demands are placed on the comprehensive performance and weight reduction effect of aluminium alloy structures.

History of Aircraft-grade Aluminum

The development of Aircraft-grade aluminum has three main stories.

The 1930s-1960s:

The main objective in the 1950s was to reduce weight and increase alloy strength. 2XXX series aluminium alloys made all-metal aircraft mainstream, while 7XXX series aluminium alloys, represented by the early 7075, made the stratospheric flight possible for passenger aircraft, represented by the DC-3, B-29 & 70.

The 1960s-1990s:

In the 1960s and 1970s, the main objective was to improve the durability and damage tolerance of the alloys, with the development of 7XXX series alloys T73 and T76 in the heat-treated condition, 7050 alloys, and high purity alloys, which improved tensile strength while taking into account fatigue characteristics, represented by the A300 series and 777.

From 2000 to the present

the third generation of aluminium alloys, represented by Aluminium-lithium alloys, has been increasingly used in new aircraft types, including the A220 and C919, in response to competition from composite materials. In addition to aluminium-lithium alloys, aluminum-based composites and superplastic forming aluminium alloys are also key research directions in aluminium for Aerospace.

How Aluminium alloys used in Aerospace?

Aluminum alloys are vital for designing a commercial aircraft or building a sophisticated space shuttle.
Aluminium alloys are most commonly used in manufacturing fuselages, wings, and support structures and are mainly used as structural materials such as skins, frames, propellers, fuel tanks, wall panels, and landing gear struts.
Aluminum alloy in Aircraft construction

2024-T3

One of the most common high-strength aluminium alloys. The 2024-T3 aluminium sheet has both high strength and excellent fatigue resistance. And 2024-Alclad makes up for the lack of corrosion resistance of the 2024 alloy itself, thanks to its cladding alloy. Typical applications for 2024-T3 aluminium sheets are fuselage and wing skins, fairings, aircraft structures, and repair and restoration.

6061-T6

This alloy has very good corrosion resistance and high precision machinability, and good welding properties. 6061-T6 aluminium sheet has a strength level of approximately that of mild steel. 6061-T6 aluminium sheet is typically used for aircraft landing gear, truck bodies, and frames, structural components, etc.

5052-H32

This is a non-heat-treatable alloy with high strength. 5052 aluminum plate has higher fatigue strength than most alloys, excellent corrosion resistance, especially in marine applications, with good machinability. This type of aluminum plate is commonly used to build fuel tanks.

3003-H14

The most widely used aluminium alloy also known as Al-Mn alloy. 3003-H14 aluminium sheet has good machinability and can be deep drawn, spun, welded or brazed. 3003 aluminium sheet is not heat treatable. This aluminium sheet is widely used for the plating of hoods and baffles.

7075

The most important aviation high strength aluminum alloy. They are mainly used to strengthen aluminum aircraft structural parts. The 7075 aluminium alloy plate contains copper (1.6%), magnesium (2.5%) and zinc (5.6%), but the copper content makes it difficult to weld. However, its anodic oxidation effect is excellent and has good processability.

Trends in Aircraft-grade Aluminum

Deep and systematic studies have been carried out on the composition and synthesis method, rolling/extrusion/forging/heat treatment process, part processing, material and structure service performance characterization of aluminum alloys used in Aerospace, the material product development has already formed the seriation, has also obtained a series of remarkable achievements in the application aspect.

Especially since the 1980s, with the development of aircraft damage tolerance and durability design criteria, higher requirements are put forward for the alloy’s strength, fracture toughness, corrosion resistance, and fatigue resistance.

The sizeable integral panel structure

The wide use of sizeable integral panel structure has become an essential means to improve the structural efficiency, reduce the number of parts, reduce the cost and shorten the development cycle of the new generation aircraft. 

This design and manufacturing method puts forward stringent requirements for aluminum alloy materials: the maximum thickness of aluminum alloy forgings or pre-drawing plates often needs to reach more than 150 mm, and the comprehensive properties of components with different thicknesses are highly uniform, at the same time, it should have excellent strength-plasticity-fracture toughness-anti-fatigue performance-anti-stress corrosion and anti-spalling corrosion performance match.

Boeing B747

For example, with the Boeing B747, the number of parts was reduced from 129 to 7, the cost was reduced by 25% and crack expansion life and residual strength were both increased by a factor of 3.

At present, the development direction of aluminum alloy is to develop the thick plate material with low internal stress. The thick plate is widely used in manufacturing technology to realize the forming of integral structural parts, to replace the parts assembled with many parts before.

However, research has also shown that more and more manufacturers (Boeing, Airbus) are using carbon fiber and other non-metallic materials in aircraft manufacturing, as these materials can be made into almost any form and radian. Over time, these materials will likely prove to be as reliable as aluminum in resisting UV damage. Let’s wait and see!   Subscribe to our newsletter.

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