Cyclic character of the evolution of the defect structure and the properties of metallic materials during megaplastic deformation

The principle of nonequilibrium evolution thermodynamics is applied to describe the cyclic evolution of the defect structures in metallic materials subjected to megaplastic (severe) plastic deformation. A unimodal distribution of defects over deformation-induced dislocations and the grain boundaries that appear during dynamic recrystallization is considered as an initial model. It is shown that taking into account memory (inertia) effects during deformation-induced restructuring transforms basic relations to the form characteristic of wave equations with damping. In this case, a deformed system executes damped oscillations and gradually reaches stationary structural parameters.