Statistically motivated model of mechanisms controlling evolution of deformation band substructure

Abstract

Deformation bands are interpreted as a spontaneously formed microstructure caused by anisotropy induced by the slip nature of plastic deformation. The gradient terms in the proposed constitutive equations have been derived by averaging the assembly of discrete dislocations. The rigid-plastic model points to the main constituents which control the fragmentation mechanism: anisotropy of the hardening matrix, anisotropic resistance of the boundaries to slip, and the bowing (Orowan) stress. For symmetric double slip compression, the model provides an explanation of the observed band orientation and band width, and of the significant change in structural morphology seen as the band reorientation occurs at large strains. The predictions are in favorable agreement with available observations.