Titanium for Damage Tolerance Applications on A380

摘要

A priority task in the development of the new Airbus A380 aircraft is to reduce its weight. This led to the introduction of titanium alloys as a substitute to steel. An example is the primary structure of current aircraft pylons. However, consideration of damage tolerance requirements is crucial, especially for pylon parts such as lateral panels, spars, shackles. Therefore, the titanium alloy Ti6Al4V was chosen in the beta annealed condition, because this heat treatment maximizes the fracture toughness and minimizes the crack growth rate as compared to the alpha beta annealed tempered condition. Furthermore, Ti6Al4V has been used extensively in aerospace implying a huge amount of experience with this alloy. For example, beta annealed Ti6Al4V was used for frame interlay of the Aerospatiale ATR 42 aircraft. However, some drawbacks of the beta annealing condition have to be kept in mind, namely loss of ductility and reduction of fatigue strength. Improvements could be achieved by water quenching from above the beta transition temperature which refines the transformed structure but also leads to severe flatness distortion on large plates. Furthermore, other titanium alloys will be used in the A380 aircraft as well. Because high tensile strength is required for fitting bolts between wing and pylon, near beta alloys like Ti10V2Fe3Al will be used.