On the fatigue strength enhancement of additive manufactured AlSi10Mg parts by mechanical and thermal post-processing

Abstract

Selective laser melting fabricated materials regularly exhibit excellent static strength, thanks to the very high thermal gradient that characterizes the process; however, their performance under dynamic loading is somehow restricted due to the limited ductility, tensile residual stresses, the defect density and the inadequate surface morphology in the as built configuration. Currently mechanical or electrochemical surface polishing steps combined with various heat treatments are integrated into the production lines to respectively address these issues. However, these methods are reported to occasionally lead to inconsistent results apart from the burden of additional costs. Herein, we applied various post treatments including shot peening, sand blasting and heat treatment to evaluate their individual and synergetic effect to tackle the aforementioned challenges. Physical, microstructural and mechanical properties of SLM fabricated AlSi10Mg specimens were investigated with special focus on fatigue strength. The results highlight that appropriate post treatments can significantly enhance the fatigue performance of SLM specimens resulting in characteristics that are comparable and even better than conventionally manufactured material. Surface treatments, in particular, were found to be efficient in significantly enhancing the fatigue strength, while eliminating the necessity of polishing steps that are currently applied on as built material.