On the origin of shear bands in textured polycrystals

The relaxation of constraints in nonequiaxed grains, which is the basis of a new theory of polycrystal deformation, permits the development of strain heterogeneities on a grain scale. Shear bands are then expected to form when there is sufficient textural softening. This was evaluated for an idealized rolling process, in which shears in the transverse plane were allowed. The result is that grain-scale shear bands should be inclined to the rolling direction preferentially at angles of 230 and 370. An analysis of the degree of textural softening incurred by sample-scale shear bands as a function of hypothetical angles indicates that such shear bands should occur preferentially at +-450