Investigation of the influence of strain induced junction disclinations on hardening and nucleation of cracks during plastic deformation of polycrystals

An influence of elastic field of strain induced junction disclinations on hardening and nucleation of a micro-crack in a head of edge lattice dislocations pile-up is considered. Computer simulation method is used to calculate critical external stress for plastic shear propagation throw a force barrier induced by junction disclination. A qualitative explanation is given for the experimentally observed essential growth of the flow stress at sufficiently large plastic deformations. It is shown that the appearance of junction disclinations suppress nucleation of micro-cracks according to the mechanism of pile-up head dislocations confluence proposed by Stroh [1].