Mechanism of ultrasonic rolling on surface strengthening of selective laser melted AlSi 10 Mg alloy

Abstract This study experimentally investigates the influence of ultrasonic surface rolling (USRP) on the microstructural evolution of AlSi 10 Mg alloy prepared by selective laser melting (SLM), and explores the mechanism of USRP. Surface morphology was examined by electron backscatter diffraction (EBSD). By comparing the measured data with and without USRP treatment, the results show that the proportion of grains greater than 10 μm on the top surface of the USRP-treated sample was reduced from 68 percent to 29 percent, and the proportion of grains greater than 10 μm on the side surface of the sample was reduced from 84 percent to 28.1 percent. USRP leads to slip and grain boundary movement. Under the effect of ultrasonic impact and static loading, grain refinement occurred on the processed surface. USRP processing induces severe plastic deformation at the material surface, leading to extensive dislocation slip and proliferation, which significantly increases dislocation density. The high-density dislocations undergo rearrangement and evolution, promoting grain refinement.