Study on the effect of ultrasonic rolling on the microstructure and fatigue properties of A03600 aluminum alloy

The surface of A03600 aluminum alloy was subjected to ultrasonic rolling process (USRP) treatment and its properties were optimized by changing the parameters. Microstructure characteristics were analyzed using SEM, EBSD, and TEM, and the fatigue properties and residual stresses of A03600 aluminum alloy with different USRP processes were tested using rotational bending fatigue test and gradient residual stress test. The grain refinement mechanism and hardening mechanism were discussed. The results show that after USRP processing, the surface grain refinement and severe plastic deformation occurred on the surface, and a hardened layer of about 550 mu m was formed, which improved the surface structure density and reduced the surface roughness. After USRP treatment, the crack source density was reduced, and the fatigue fracture crack source was shifted from the surface to the secondary deformation zone, at a stress level of 100 MPa, the fatigue performance is improved by a factor of about 5. Meanwhile, the increase of gradient hardness and more regular grain orientation are the key factors leading to the improvement of fatigue performance of A03600 aluminum alloy.