Effect of Cryogenic Treatment on Mechanical Properties of Aluminium Alloy AA2014

摘要

AA2014 is a high-strength Al-Cu alloy which is used for highly stressed components in aircraft fuselage, wing covers and military truck frames due to their excellent strength-to-weight ratio, and its properties are usually enhanced by further heat treatment. In this work, the conventional heat treatment process is replaced with shallow cryogenic treatment (SCT) with eight different soaking hours for enhancing the mechanical properties and followed by a tempering process at 160 °C for 18 h. The dislocation effect due to SCT produces volume contraction and grain rotations and shrinking the vacancies and micropores, present in the matrix. Due to the metallurgical behaviour of the strengthening precipitates Theta(9) phase (CuAl_2) and the insoluble particles which are finely dispersed along the grain boundaries of the matrix during the tempering process, results in higher tensile strength, elongation and fracture toughness. The maximum percentage improvement in microhardness, ultimate tensile strength, elongation, fracture toughness and wear rate are 40, 1.28, 10, 23 and 48, respectively, for 18 h of shallow cryogenic treatment, and the property varies for different soaking hours. With these improvements, AA2014 can provide better mechanical properties than the recently developed aluminium alloys with reduced cost.