MILITARY, AEROSPACE & DEFENCE FEATURE
Material matters
Marta Danylenko, marketing manager at online materials database Matmatch, talks about the alloys used in aerospace engineering and their applications, and discusses what the future holds for aerospace materials
B
eing lightweight, strong, and with a high resistance to corrosion, aluminium has been used in the aerospace industry from as far back as the 19th Century, when Count Ferdinand
Zeppelin made the frames of his iconic airships from the material. The Wright brothers also chose aluminium for the cylinder block and other engine parts for their first manned flight in 1903. This was the first time an aluminium alloy had been heat-strengthened, a discovery that prompted the preference for aluminium in aerospace engineering. However, the advent of jumbo jets and long-haul international flights – where the shell and
engine parts had to be extremely durable and resistant to fatigue – led to the development and use of many different types of aluminium alloys.
ALUMINIUM ALLOYS Second only to AA 2024 in terms of its popularity in aerospace engineering, AA 2014 is a strong and tough metal and is suitable for arc and resistance welding. However, as it has poor corrosion resistance, it is often found in the internal structure or framework of aircraft rather than the shell. Aluminium alloy 2024 is probably the most widely used alloy for aircraft. As a high-grade
alloy with excellent fatigue resistance and high tensile strength of around 470 MPa, this is used primarily in sheet forms such as for the fuselage and wings. Of the non-heat treatable grades of alloy, AA 5052 provides the highest strength and is
highly ductile, so it can be formed into a variety of shapes including engine components and fittings. It is also highly corrosion resistant. Easily welded and manipulated, AA 6061 alloy is very light and fairly strong, making it
ideal for fuselage and wings. This is common in light aircraft. AA 7050, meanwhile, has high corrosion resistance and maintains strength in wide sections. This makes it more resistant to fractures than other alloys. It is commonly used in wing skins and fuselage, especially in military aircraft. Then there is AA 7068, the strongest alloy available today. Combined with its low mass, this is ideal for military aircraft. With similar strength properties to steel due to its high levels of Zinc, AA 7075 has excellent fatigue resistance. As this can be machined easily, it was a popular choice for fighter planes in World War II, and is still used frequently in military aircraft to this day. AA 2219 is an aluminium alloy that provides maximum strength at elevated temperatures. Used for the external fuel tank of the space shuttle Columbia, this has good weldability, but the welds need heat-treating to preserve resistance against corrosion. AA 6063 is mainly used for aesthetic and architectural finishes; while AA 7475 is highly resistant to fracture and fatigue. Due to its toughness, this is sometimes found in fuselage bulkheads of larger aircraft.
THE FUTURE OF ALUMINIUM ALLOYS It is predicted that demand for aluminium will double over the next decade, and by 2025 there will be a global demand of 80 million tonnes. As a result, the aerospace industry is increasingly looking to recycled alloys. But, there is also a push for innovation in the materials used, as well as the design structure of aircraft. As an example, aluminium-lithium alloys have been developed to reduce the weight of aircraft and therefore improve the performance. As developing countries become more involved in the aerospace industry, and with increased
investment, there will be further innovation in aluminium alloys over the coming years. Matmatch
https://matmatch.com www.first-sensor.com
We are there when innovation leads to an edge.
Extreme temperature changes, accelerations and vibrations – our sensors, modules and cus- tomer-specific systems meet the exceptional requirements for reliability and resilience in the aerospace industry.
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