Crystal Plasticity Finite Element Simulations of Grain Interaction and Orientation Fragmentation during Plastic Deformation of BCC Metals

Deformation of a grain in polycrystalline metals is restricted or forced by deformation of neighbor grains during plastic deformation processes. It also gives influence to deformation of neighbor grains at the same time. Interaction between grains causes inhomogeneous local deformation and texture during plastic deformation. Prediction of inhomogeneous local deformation and texture is important in understanding of recrystallization texture. Taylor-type polycrystal models which have been employed in prediction of texture evolution cannot count on grain interaction. In this work, a finite element simulation based on the crystal plasticity has been carried out to investigate the effect of grain interaction on local deformation and texture evolution. An artificially configured BCC bicrystal that consists of a crystal located at center and a surrounding neighbor crystal has been employed in plane strain compression simulation. Several pairs of specific orientations have been chosen for initial orientations of the bicrystal. Deformation and texture evolution of the center crystal in the bicrystal have been investigated changing the initial orientation of the surrounding crystal. The simulation results show that deformation and texture evolution near crystal boundary can be different from those at the center region of the crystal. Orientation fragmentation, which results in great lattice curvature is observed in a center grain with an initial metastable orientation. Simulation shows that a metastable crystal always breaks up during deformation and the grain interaction changes only the pattern of grain breakup