Multiscale modeling of back-stress evolution in equal-channel angular pressing: from one pass to multiple passes

Fine-grained materials produced by equalchannel angular pressing (ECAP) exhibit kinematic hardening due to the existence of a back-stress. This article presents a new dislocation-based model, which is able to describe the tension/compression asymmetry of the ECAP processed commercial purity aluminum. By introducing
strain relaxation, and relating the back-stress to the inhomogeneous dislocation density distribution in cell walls and in cell interiors, the model can accurately predict the evolution of the dislocation densities, the cell size, and the back-stress. Compared to the other back-stress models, it takes into account the microstructure evolution and gives a better prediction.