Vibration fatigue performance improvement in 2024-T351 aluminum alloy by ultrasonic-assisted laser shock peening

To improve the fatigue resistance of 2024-T351 aluminum alloys, ultrasonic-assisted laser shock peening (ULP) was proposed in this study, which combined ultrasonic shock peening (UP) and laser shock peening (LP) for improving the microstructure and mechanical properties. The microstructure, residual stress, and microhardness of four specimen types—untreated, UPed, LPed, and ULPed—were tested, and their effects on vibration fatigue life were analyzed. The results show that the dislocation density is increased significantly, and the grains are obviously refined by ULP. Consequently, the amplitudes of compressive residual stress and microhardness are increased a lot by ULP to inhibit crack initiation and propagation, thus significantly increase the vibration fatigue life.