Occurrence of shear bands in heavily rolled cubic metals

Abstract

The conditions under which shear bands occur in rolling have been examined from a macroscopic standpoint. It is found that the main features of the observed shear bands can be explained by macroscopic analysis without recourse to detailed crystallographic mechanisms. The bands form as the result of load instability caused by geometric softening and it is shown that the strain at which this occurs is determined by the requirement of developing a sufficiently strong preferred orientation. The most notable cause of instability that does not arise from geometric softening is a load drop caused by dislocation multiplication. It is shown that in a material with only a weak preferred orientation the shear bands in this case lie parallel to the plane of maximum shear stress. In the case of geometric softening the plastic anisotropy is manifest by the shear bands deviating from this plane. Detailed explanations are given.