Grain refinement versus voids accumulation during severe plastic deformations of polycrystals: mathematical simulation

We view the emergence of disorientation boundaries in crystals and the formation of micropores as complementary mechanisms of relaxation of internal strain during severe plastic deformations of polycrystals. Using an assumption of self-similarity of the grain refinement process, we obtain kinetic equations for two scalar parameters characterizing the structure of the material: the total area of fragment boundaries and the total volume of micropores per unit volume of material. We show that the model captures the main regularities of large plastic deformations of metals with high stacking-fault energy. The analysis of the model yields a number of recommendations for increasing the effectiveness of severe plastic deformation processes.