Anisotropic tension-compression asymmetry in SLM 316L stainless steel

Abstract

Selective laser melted (SLM) metallic materials commonly possess typical columnar grains growing epitaxially along the building direction and substantial microscale internal stresses. However, the coupling impact of columnar grains and residual stresses on the mechanical behavior of SLM materials needs further research. Here, by combining experiments and crystal plasticity finite element (CPFE) simulations, tension and compression tests in different directions are performed to investigate the anisotropic tension-compression asymmetry of SLM 316 L stainless steel. The comparison of the data and model predictions shows that the simulated true stress-strain behavior under uniaxial tension and uniaxial compression can well predict the experimental trends qualitatively. The CPFE simulation results further reveal that the tension-compression asymmetry in the building direction results from directional internal stresses. In addition, the tension-compression asymmetry perpendicular to the building direction is correlated with the microstructure and internal stresses. It is inferred that the heterogeneous grain distribution induces plastic anisotropy in the stress level of tensile and compressive behaviors. This work establishes a comprehensive intrinsic connection between materials and properties of SLM stainless steel.