Synergistic Effects of Surface Roughness & Volumetric Defects on the Mechanical Behavior of Additively Manufactured AlSi10Mg Parts

Abstract

Surface roughness is known to significantly impact the fatigue behavior of additively manufactured metals. As-printed surface roughness features can have a negative impact on fatigue life by facilitating crack initiation. Surface treatments can improve the fatigue behavior of additively manufactured materials by removing as-printed surface roughness and minimizing the localized stress intensity factors. This study examines the synergistic effect surface roughness and porosity for five different surface conditions, un-machined, only polished, shallow machined, deep machined, and machined and polished, on the fatigue behavior of additively manufactured AlSi10Mg. Tensile properties showed small differences between surface conditions. Surface condition had little impact on fatigue life due to defects and surface roughness having similar elastic stress concentration factors and fatigue notch factors. Crack initiation occurred from surface roughness features in the un-machined conditions. Crack initiation occurred from defects in the machined conditions, with defect size and aspect ratio playing a role in fatigue life.