Microstructural modeling of anisotropic plasticity in large scale additively manufactured 316L stainless steel

Abstract

In this paper, the anisotropic mechanical response triggered by specific microstructures encountered in wire + arc additively manufactured 316L stainless steels is analyzed. For this purpose, a representative volume element is generated, with an internal geometry that is based on an average periodic fusion zone shape. The large columnar grain geometry with different preferred directions within a single fusion zone is reconstructed with an anisotropic Voronoi algorithm. Grain orientations are extracted from experimental data of different regions within a single sample. Crystal plasticity finite element simulations are performed to predict the macroscopic yield behavior under various loading angles. It is observed that the anisotropic response varies significantly within a single sample, which is essentially caused by differences in the texture. A spatial correlation between the orientation of a grain and its location within the fusion zone is identified, allowing to distinguish clusters of grains with a similar orientation. As a result, strain localizes in a global shear band across the entire height of the fusion zone, which prominently influences the macroscopic response. A comparison of the results relative to a standard isotropic Voronoi grain geometry shows that the elongated geometry of the grains does not influence the macroscopic yield behavior significantly. The local crystallographic orientations are dominating instead, whereby the correlation between location and orientation of grains has to be taken into account.