Quantifying microstructure- and deformation-mode-dependent heterogeneity using crystal plasticity simulations

Plastic deformation in polycrystalline metals is intrinsically heterogeneous because crystallographic anisotropy and intergranular constraint cause non-uniform partitioning of strain, stress, and hardening. Although both grain morphology and deformation mode are known to influence this behavior, their relative roles have not been systematically quantified within a single microstructure-informed framework. In this study, a crystal plasticity finite element method (CPFEM) framework is developed to explicitly quantify deformation heterogeneity in AA5052 sheet under four representative deformation modes: shear, uniaxial tension, plane strain tension, and equi-biaxial tension. From the observed microstructure, realistic representative volume elements (RVEs) with equiaxed, elongated, and mixed grain morphologies are constructed to isolate morphology effects while preserving measured texture and microstructural statistics. A key contribution of this work is the separation of deformation heterogeneity into two complementary features: heterogeneity severity and localization connectivity. The statistical measures quantify the magnitude of local strain/stress fluctuations, whereas the hotspot connectivity analysis captures the spatial organization of localization pathways. The results show that deformation mode primarily governs heterogeneity severity and overall hotspot connectivity through differences in kinematic constraint, accumulated plastic slip, and hardening heterogeneity. Under the measured AA5052 texture condition considered here, grain morphology further modifies the topology and preferred direction of localization: elongated grains promote directional hotspot pathways, while equiaxed and mixed morphologies tend to form more spatially distributed hotspot networks under severe deformation modes. These findings provide a local-field mechanistic basis for understanding the coupled effects of deformation mode, and grain morphology on localization in rolled aluminum sheets.