The effects of cyclic-strengthening interrupted aging on the microstructure evolution and stress corrosion resistance of aluminum alloy

Hunan Engineering Research Center of Forming Technology and Damage Resistance Evaluation for High Efficiency Light Alloy Components, Hunan University of Science and Technology, Xiangtan, 411201, PR China

^* Corresponding author: yqchen1984@163.com

Abstract

The stress corrosion is likely to occur in high-strength aluminium alloys especially in corrosive environments, which is a key factor affecting the service safety of aluminium alloy components. In this study, a new kind of aging method, interrupted by cyclic-strengthening (CS) at its earlier stage, was applied in 7075 aluminium alloy plates. Compared with the traditional peak aging T6 state, the continuous precipitation can hardly take place at grain boundaries (GB) in CS interrupted aging. This greatly weakened the electrochemical reaction between the GB precipitates and aluminium matrix, resulting in the higher self-corrosion potential and better stress corrosion resistance of alloy. Besides, after CS interrupted aging, a larger number of atom clusters and much finer inner-grain precipitates formed in 7075 aluminium alloys produced by the repeated dislocation cutting during CS, which hinders the movement of dislocations and improve the tensile strength of alloy almost without loss of ductility.