Deformation Geometry and Through-Thickness Strain Gradients in Asymmetric Rolling

Abstract

Experiments and simulations focusing on cold rolling under conditions where the work roll velocities are different (asymmetric rolling) have been performed to provide a basic framework for understanding the effects of the roll velocity ratio and deformation geometry on through thickness shear strain development. It is shown that deformation geometry, controlled by varying the reduction per pass, has a significant impact on the through thickness shear strain gradients at a given level of asymmetry. Large reductions per pass lead to more uniform through thickness shear strains, but lower overall shear strain magnitudes compared to rolling conditions involving small reductions per pass. Moreover, the results show that a critical value of the roll velocity ratio exists, for a fixed set of rolling conditions, above which the shear strains induced by asymmetric rolling remain unchanged. This is interpreted based on the relative importance of geometrically induced shear strains and those arising from frictional effects. In this context, the position of the neutral points plays a vital role.