Numerical study on the effect of crystallographic orientation on mechanical behavior and its anisotropy of laser powder bed fusion AlSi10Mg

Abstract

Anisotropic strength and ductility are limiting factors for the application of laser powder bed fusion AlSi10Mg. Previous efforts were devoted to explaining the origins of anisotropy mainly from the geometrical orientations of the Al-Si cellular structure and melt pool border, but the effect of crystallographic orientation is still unexplored. The present work aims to assess the mechanical behavior of Al-Si cellular structure using crystal plasticity model, with a focus on how grain orientation affects strength, damage initiation and their anisotropy. Forty-four crystallographic orientations were generated and assigned to a representative volume element resembling the real Al-Si cellular structure. For each orientation, simulations of uniaxial tension along the building direction and the perpendicular direction were performed. It is found that the grain orientation has a huge influence on both strength and damage sensitivity. Nevertheless, the correlation between strength and orientation cannot be established with the Schmid or Taylor factors due to the influence of the elongated Si network. Comparing the results for the two loading directions, strength anisotropy is revealed to present a weak dependence on grain orientation, whereas damage anisotropy varies significantly in the orientation space. The findings of this work can be used for up-scale modeling of mechanical behavior of additively manufactured AlSi10Mg.