The role of dislocations in cyclically deformed metal polycrystals

Persistent slip bands (PSBs) are surface microstructural features that commonly arise when a polycrystalline metal experiences mechanical fatigue. As dislocations are carriers of plastic strain and PSBs are essentially strain localisation regions, the evolution of dislocations is expected to be pivotal in determining a material's fatigue behaviour. The role of dislocations is investigated here by considering their kinematic activities namely, dislocation generation, annihilation and trapping incorporated within crystal plasticity theory. The results are consistent with experimental observations reported in the literature, indicating that PSB formation is due to the accumulation of edge dislocation dipoles caused by trapping events.