Microstructure evolution of stainless steel subjected to biaxial load path changes: In-situ neutron diffraction and multi-scale modeling

The lattice strain and intensity evolution obtained from in-situ neutron diffraction experiments of 316L cruciform samples subjected to 45 degrees and 90 degrees load path changes are presented and predicted using the multi-scale modeling approach proposed in Upadhyay et al., IJP 108 (2018) 144-168. At the macroscale, the multi-scale approach uses the implementation of the viscoplastic self-consistent polycrystalline model as a user-material into ABAQUS finite element framework to predict the non-linearly coupled gauge stresses of the cruciform geometry. The predicted gauge stresses are then used to drive the elasto-viscoplastic fast Fourier transform polycrystalline model to predict the lattice strain and intensity evolutions. Both models use the same dislocation density based hardening law suitable for load path changes. The predicted lattice strain and intensity evolutions match well with the experimental measurements for all reflections studied. The simulation results are analyzed in detail to understand the role of elastic anisotropy, plastic slip, grain neighborhood interactions and cruciform geometry on the microstructural evolution during biaxial load path changes.