Aircraft materials and properties
Materials that contribute to the structure and manufacture of aircraft.
Aluminium alloys
Aluminium alloys used on most types of aircraft because it is lightweight and strong.
Aluminium alloys don’t corrode as readily as steel. But because they lose their
strength at high temperatures, they cannot be used for skin surfaces that become
very hot on airplanes that fly faster than twice the speed of sound.
Steel
Steel can be up to four times stronger and three times stiffer than aluminium, but it
is also three times heavier. It is used for certain components like landing gear, where
strength and hardness are especially important. It has also been used for the skin of
some high-speed airplanes, because it holds its strength at higher temperatures
better than aluminium.
Carbone fibre
Carbon fibre is one of several types of composite materials that are becoming widely
used for many aircraft structures and components. These materials typically consist
of carbon fibres embedded in a resin. Thin sheets of the material can be stacked in
various ways to meet specific strength or stiffness needs. Carbone fibre is about as
strong as aluminium but weighs about half as much. The new Airbus A350 is 53%
carbon composite with the majority of the wings and fuselage constructed from
carbon fibre.
Titanium
Titanium is about as strong as steel but weighs less, although it is not as light as
aluminium. It holds its strength at high temperatures and resists corrosion better
than steel or aluminium. Titanium is expensive, these characteristics have led to its
greater use in modern aircraft. Titanium is used in a variety of parts in aircraft
construction, used on the exterior framework and in the engine. Titanium can be
found all over planes on parts from landing gear, internal components of the wings,
propellers and engine components.
Why Aluminium alloys are used in the construction of aircraft?
The reason aluminium is used in aviation is because of its properties, these include
low density, high strength, superior malleability, easy machining, excellent corrosion
resistance and good thermal and electrical conductivity. Aluminium can be mixed
together to give it alternative properties.
Some common aluminium alloys used in aircraft manufacture;
2024-T3 - This is the most common of the high-strength aluminium alloys and is used
in the workshop and is also called Alcad. It is used in the aircraft because of its
strength and excellent fatigue resistance. Uses for aluminium sheet are aircraft skins,
cowls, aircraft structures, and also for repair and restoration. Alclad has a very thin
layer of pure aluminium on the surface.
6061-T6 - This alloy has a very good corrosion resistance and finishing ability. The
strength level of 6061-T6 aluminium sheet is about that of mild steel. 6061-T6
aluminium sheet can be fabricated by most of the commonly used techniques.
Typical uses are aircraft landing mats, truck bodies and frames, structural
components and more.
5052-H32 – This aluminium alloy has the highest strength in the non-heat treatable
alloys. It is not structural. 5052 aluminium sheet has higher fatigue strength than
most alloys. 5052 aluminium sheet has excellent corrosion resistance and has
excellent workability. 5052 aluminium sheet is most commonly used to make fuel
tanks.
3003-H14 - Most widely used of aluminium alloys, pure aluminium with manganese
added for strength, approximately 20% stronger than other aluminium alloys. 3003H14 aluminium sheet has great workability and may be deep drawn, spun, welded or
brazed. 3003 aluminium sheet is non-heat treatable. This aluminium sheet is widely
used for cowls and baffle plating.
7075 -Aircraft manufacturers use high-strength alloys to strengthen aluminium
aircraft structures. Aluminium alloy 7075 has Copper (1.6%), Magnesium (2.5%) and
zinc (5.6%) added for ultimate strength and it anodizes really well. 7075 aluminium
also has very good machinability characteristics.