Indirect laser peening is a new laser peening technique and modifies the mechanical properties of the surface of the substrate. Metal sheet protects the substrate surface from heat affect by a plasma with laser irradiation. Because the metal sheet absorbs laser energy and reduces the peening efficiency, the features of indirect laser peening for several aluminum alloys were investigated in this study. The changes of mechanical properties by indirect laser peening were discussed by the comparison to the mechanical properties of as-received state.
