Tailoring the surface integrity and fatigue performance of 3D-printed AlSi10Mg alloy through laser shock peening

Abstract

Additive manufacturing technology has garnered significant attention and experienced rapid development in industrial manufacturing in recent years. Aluminum alloys, widely used in aerospace and automotive sectors, are ideal candidates for laser metal additive manufacturing (AM). However, the additive manufacturing process introduces defects and tensile residual stresses, leading to a decline in fatigue properties of the alloy. In this study, laser shock peening (LSP) was employed to modify the surface of AlSi10Mg alloy fabricated by direct metal laser sintering (DMLS) to tailor its surface integrity and fatigue performance, with mechanically polished samples used for comparison. After LSP treatment, the surface hardness of the alloy increased from 132.8 HV to 157.5 HV. Moreover, the tensile residual stress generated during rapid cooling was effectively transformed into compressive residual stress on the surface. As a combined effect of enhanced hardness and residual stress conversion, the rotary bending fatigue life of the alloy was improved by 1.8–2.8 times under applied stress levels of 40–140 MPa. Although polishing yielded a smoother surface, it provided only limited improvement in fatigue performance. These findings demonstrate that the mechanical properties of additively manufactured AlSi10Mg alloys can be significantly optimized through LSP.