The Effect of 3D Representative Volume Element Grain Morphology Resolution on the Prediction of Fracture and Damage Accumulation for Multiphase Hot‐Stamped Steels

Abstract

This work investigates the effect of 3D representative volume element (RVE) grain morphology resolution on the prediction of fracture and damage evolution for tailor hot stamped steels. Scanning electron micrographs were used to build RVE meshes from coarse‐8 × 8 (<1 elements μm−3) to high‐50 × 50 (53–81 elements μm−3) element densities. For a uniaxial stress‐state, the tailored material condition (TMC1) (ferrite‐pearlite‐martensite) RVE nucleated voids due to separation between small martensite grains and the RVE fracture strain was 0.41 and 0.53 for the 50 × 50 and 25 × 25 RVE, respectively. The TMC3 (ferrite‐bainite‐martensite) RVE predicted high strain partitioning between the irregularly shaped martensite grains and the higher resolution RVE predicts a 39% lower fracture strain. The large grained martensite‐bainite TMC5 RVE predicted relatively similar void accumulation and strain partitioning behavior for the 50 × 50 and 25 × 25 RVE models, while the coarser 13 × 13 and 8 × 8 models predicted higher fracture strains due to low grain morphology resolution. Compared to an experimentally derived fracture locus, plane strain and equibiaxial deformation of the RVEs was shown to predict the equivalent fracture strains reasonably well, but like in the uniaxial case, the coarser RVEs overpredict the fracture strain.