Some early high speed aircraft such as the BAC-188 experimental design had a skin of titanium- stabilised austenitic stainless steel to withstand the temperatures of 300 oC experienced during flight. It flew briefly in the early 1960s. However for the lower speeds in commercial aircraft aluminium has sufficient temperature capability.
From the first commercial passenger airliner, the Comet, developments in our understanding of the physical metallurgy of steels and other metallic materials have allowed significant improvements in fuel consumption for aero engines and for the per passenger fuel consumption per km a reduction of 70% has been achieved. This has been accompanied by a four-fold reduction in noise.
In 2016, aviation accounted for 3.6% of the total EU28 greenhouse gas emissions. (The EU28 emissions are 20% of the world total). The figure is 13.4% for all transport, in which the automotive sector is the main contributor. As greenhouse gas emissions from sectors other than transport have declined due to new technologies and legislation the contribution of aviation to the total emissions becomes increasingly significant, more than doubling since 1990. Hence there is a constant drive to reduce aviation emissions still further.
For aerospace applications steel competes with other materials such as aluminium, titanium, nickel and more recently composites. This has been driven by the need for weight savings and high engine temperatures to maximize efficiency. However there are critical areas in the aircraft where steel is still widely used: the main shaft in the engine, landing gear and actuators. The different requirements for these applications illustrate the broad range of property combinations available with steel compared to other metallic systems.