Influence of Laser Shock Peening and Ultrasonic Nanocrystal Surface Modification on Residual Stress, Microstructure, and Corrosion-Fatigue Behavior of Aluminum 7075-T6

Aluminum 7075-T6 alloy was subjected to Laser Shock Peening without Coating (LSPwC) and Ultrasonic Nanocrystal Surface Modification (UNSM) to boost fatigue performance in both air and corrosive environment. Severe plastic deformation (SPD) caused by UNSM treatment induced significantly higher (similar to 3.5 x) surface compressive residual stress than LSPwC, while the intense shockwaves generated by LSPwC introduced similar to 3 x higher depth of compression. Electrochemical results confirmed improved polarization resistance and reduced corrosion rate post LSPwC, which is mainly attributed to its oxide layer and near-surface microstructural homogenization. Changes in the mechanical and corrosion behavior of the alloy after LSPwC produced up to similar to 650 pct augment in corrosion-fatigue life over base material while UNSM improved the performance by up to similar to 250 pct.