Coupling effects of electrochemical corrosion and pre-applied tensile stress on performance degradation of high-strength aluminum alloy in deep-sea environment

• The deep-sea mechanics-electrochemical corrosion experiments are designed to study the performance degradation of high-strength aluminum alloy in deep-sea environment. • The development mechanism of pitting corrosion under coupling effects of electrochemical corrosion and pre-applied tensile stress is explained. • The influence of pre-stress on mechanical degradation characteristics of high-strength aluminum alloy after deep-sea corrosion is investigated. High-strength aluminum (Al) alloy is widely used in deep-sea equipment, and its corrosion problem is prominent. Coupling effect of electrochemical corrosion and pre-applied tensile stress on the performance degradation of high-strength Al alloy was investigated by means of microscopic morphology observation, micro area electrochemical testing, and corrosion product analysis. Results show that hydrostatic pressure and pre-applied stress significantly promoted corrosion of Al alloy in seawater, especially under high stress conditions. Additionally, external stress significantly increases the formation of protective film cracks and sensitivity to grain corrosion. There are significant differences in corrosion behavior and mechanical degradation performance under different stress conditions. Coupling effects lead to the decrement in mechanical properties and the enhancement of stress corrosion sensitivity of Al alloys.