Influence of the relaxation processes on the structure formation in pure metals and alloys under high-pressure torsion

A study has been performed on three classes of materials in which different structure-forming processes dominate, namely, cold hardening in iron and structural steels, dynamic recrystallization in copper, and pressure-induced transformation in austenite steel. These processes are shown to affect a staged character of the structure formation upon high-pressure torsion. In the case of cold hardening, the character is controlled by true strain, the growth of which results in an increase in hardness and a refinement of the structure elements. The termination of these processes can be caused by another mechanism of relaxation, e.g. phase transformation induced by high pressure. Upon dynamic recrystallization, the staged character of deformation is determined by the temperature and rate of deformation.