Multiaxial plasticity and fracture behavior of stainless steel 316L by laser powder bed fusion: Experiments and computational modeling

The multiaxial large deformation and ductile fracture behavior of laser powder bed fusion (L-PBF) additively manufactured austenitic 316L stainless steel was experimentally measured. Data from tests in two orientations, under five dissimilar stress states (shear, combined shear/tension loading states, plane strain tension, and uniaxial tension) were used to calibrate and validate anisotropic plasticity and fracture models, with different specimen geometries used to probe plasticity versus fracture. Shear softening, hypothesized to be due to shear band formation in the material due to high initial dislocation density and sub-micron cellular structures, was observed in shear dominated tests, and modeled through the adoption of a shear damage criterion in an anisotropic plasticity model. Using a combined experimental and computational approach, isotropic and anisotropic Hosford-Coulomb and modified Mohr-Coulomb ductile fracture models were calibrated for both sample orientations. The calibrated anisotropic Hosford-Coulomb fracture model best captures the stress state dependent and anisotropic failure behavior of L-PBF 316L.