The Interplay of Geometric Defects and Porosity on the Mechanical Behavior of Additively Manufactured Components

Abstract

Additive manufacturing (AM) is becoming increasingly popular, but standards for critical defect sizes and porosity levels have not been fully established. The wide range of flexibility offered by AM is unable to be exploited by designers if they do not have confidence in their components’ mechanical behavior. The goal of this study was to understand how the factors of specimen geometry, geometric defects, porosity, and base material ductility impact the performance of realistic AM exemplar components. Geometric defects, including quarter cracks, internal voids, and through holes, were intentionally manufactured into thin-walled, tapered SS 316L and AlSi10Mg AM components. Two levels of porosity were introduced by reducing the laser power in the AlSi10Mg specimens to observe interactions of porosity and the larger-scale geometric defects. Many such components were manufactured, and each component was loaded to failure. Intentionally manufactured defects decreased the failure load and displacement-to-failure for both materials. Geometric defects had a greater effect in the less ductile materials. Increasing the porosity in the AlSi10Mg above a threshold led to density-dominated component behavior, with little impact of intentional large-scale geometric defects. This work demonstrated the interactions between the flaw types and the dependence of the AM component behavior based on inherent material ductility, porosity, and presence of geometric defects. The results from this study provide valuable insight for establishing a critical porosity-defect relationship for AM metals. It also demonstrates that predicting component behavior in AM metals requires an understanding of flaws types and material properties.