The effect of grain-boundary sliding on fabric development in polycrystalline aggregates

The influence of grain-boundary sliding on fabric development in polycrystalline aggregates has been numerically modelled using the finite difference computer code FLAC. In the model we allow the co-operation of intragranular slip and grain-boundary sliding, and consider situations involving different proportional combinations of the two mechanisms. The results show that the amount of grain-boundary sliding incorporated in polycrystalline deformation relative to intragranular slip strongly influences fabric development. When the amount is small, grain-boundary sliding significantly reduces grain interaction but still ensures the dominance of intragranular deformation. Correspondingly, crystallographic preferred orientations associated with well-evolved microstructures, are even better developed in comparison with those obtained without grain-boundary sliding. When the amount of grain-boundary sliding is increased, however, polycrystalline fabric development is effectively weakened. In the extreme situation where grain-boundary sliding dominates, a total absence of crystallographic preferred orientation and microstructures results. The introduction of grain-boundary sliding weakens the dependence of intragranular deformation upon the lattice orientation of grains. With the increase of grain-boundary sliding, intragranular strains become smaller and more homogeneous. The distribution of strain is dominantly determined by the distribution of grain-boundary sliding.