MICROSTRUCTURAL SLIP LOCALIZATION IN STRAIN-SOFTENING MATERIALS

In materials that exhibit strain softening due to dislocation multipli cation and/or glide-induced destruction of dislocation obstacles, pron ounced slip localization may be observed. Plastic deformation after yi eld is characterized by a coarse and inhomogeneous slip pattern. In th e present work a statistical model of the microstructural evolution du ring strain softening is formulated. Both multiplication softening and structural softening due to obstacle destruction are taken into accou nt. The interplay between strain softening, slip localization and the formation of an inhomogeneous microstructure is studied. It is demonst rated that multiplication softening leads to transient slip heterogene ities only, while structural softening gives rise to a more permanent localization of slip which manifests itself through the formation of o bstacle-free slip channels within a microstructure of initially high o bstacle density.