Effect of multi-pass shot peening on the microstructure of LPBF AlSi10Mg alloy

In this study, we investigated the effect of multi-pass shot peening (SP) on the microstructural evolution of a Laser Powder Bed Fusion AlSi10Mg alloy. Characterization techniques included optical microscopy, scanning electron microscopy, and electron backscatter diffraction (EBSD). The results revealed that multi-pass SP induces a gradient microstructure with notable alterations in the grain structure extending to a depth of approximately 45 μm. EBSD analysis revealed that the SP treatment induced grain refinement and formation of subgrains (average distances between boundaries vary from 3.6 μm in the un-deformed area to 0.4 μm near the heavily deformed surface area). It is discussed how this refined microstructure following SP may lead to substantial improvements in mechanical properties and fatigue strength, and thus hold promises for increased performance of critical components across various industrial applications.