Optimization of surface characteristics of additively manufactured AlSi10Mg and 316L parts using shot peening

Additive manufacturing offers extensive possibilities to produce components with complex shape. However, a central challenge is the optimization of the surface layer characteristics to meet the high requirements, particularly regarding fatigue strength, in various industries Additively manufactured components in their initial (as built) state generally have surface properties that are too poor for structural applications due to tensile residual stresses, surface roughness and porosity. The focus of this paper is to investigate the effect of the shot peening process on the surface layer characteristics of laser bed powder fusion (LPBF) manufactured AlSi10Mg and 316L austenitic stainless steel. After shot peening, all specimens exhibit compressive residual stresses, with the blast pressure correlating the depth of compressive stresses, but only a moderate increase in the maximum stress level was observed. The hardness depth profile revealed increased hardness values due to work hardening up to 200 μm, with higher blasting pressures enhancing hardness in AlSi10Mg, while 316L samples showed saturation behavior at 3 and 5 bar. In addition, after shoot peening a significant reduction of the surface roughness in comparison to the as built state was achieved for both materials. Recommendations for optimal shot peening parameters are the use of 420-850 μm glass beads at 3 bar for AlSi10Mg and 300-500 μm ceramic beads at 5 bar for stainless steel 316L. • Investigation of shot peening regarding hardening, roughness, and residual stress. • Recommendations for the shot peening parameter for the treatment. • Shot peening introduces compressive residual stresses in the surface layer. • LBPF manufactured AlSi10Mg and 316L