SELF-ORGANIZATION APPROACH TO CYCLIC MICROPLASTICITY - A MODEL OF A PERSISTENT SLIP BAND

The evolution of a persistent slip band is treated as a consequence of instability transitions accompanied by a process of self-organization of dislocations stored in the deformed metal crystal. The proposed qu alitative model is analysed by the perturbation method. The first orde r perturbation analysis of the model at the state of zero hardening wh ich simulates the disintegrating dislocation vein structure predicts a n appearance of shear bands of localized slip. The second order pertur bation analysis indicates that within the lamella of localized slip a new dislocation structure of the ladder type is formed. The thickness of the PSB lamella is controlled by the internal stresses caused by th e ladder structure in the band. (C) 1998 Elsevier Science Ltd. All rig hts reserved.