Corrosion damage characteristics of aluminum alloy strengthened by ultrasonic surface rolling processing and its influence on fatigue behavior

Ultrasonic surface rolling processing (USRP) is used to strengthen 7075 aluminum alloy, the corrosion behavior during immersion is studied by electrochemical impedance spectroscopy, and fatigue performance of different samples under corrosion was tested. Results indicate that 7075 aluminum alloy matrix is prone to form pitting corrosion with a large depth to diameter ratio, multiple crack sources will appear on the surface and propagate simultaneously after pre-corrosion, which significantly reduces the fatigue life. USRP treatment delays the occurrence of pitting of 7075 aluminum alloy, the depth to diameter ratio of pits is also smaller, which reduces the damage effect of corrosion on fatigue, meanwhile, residual compressive stress value of USRP sample remains higher even after corrosion, the above comprehensive effects make its fatigue life higher than that of 7075 aluminum alloy matrix under the same corrosion time.