Microstructural modeling of grain subdivision and large strain inhomogeneous deformation modes in f.c.c. crystalline materials

In this study, evolution equations related to a heterogeneous microstructure that is physically representative of the densities and dimensions of dislocation-cells and walls have been formulated and coupled to a multiple-slip crystal plasticity formulation. Specialized finite-element methodologies have then been used to investigate how an imbalance in shear-strain amplitudes can result in deformation band formation in a cube-oriented aluminum single crystal subjected to strains of up to 30% under rolling deformation. It has been shown that a change in the microstructural morphology from matrix to transition bands occurs as the dislocation-cell size increases with decreases in the stored dislocation density and as a function of slip-system structure and orientation. Comparisons with experimental measurements and observations clearly indicate that the transition and matrix bands can occur in cube orientations as a consequence of shear strain imbalance on active slip-systems.