Nucleation recrystallization mechanisms in metals at thermomechanical processing

In the last 15-20 years, mathematical models are the most important “tool” in the design and creation of technology of thermomechanical processing of metals and alloys. This is the result of appearance of new class of models based on physical theories. Single-level macrophenomenological models based on macro experiments are replaced by crystals plasticity. Founders of physical theories of plasticity are G.I.Taylor, G.H.Bishop, R.Hill, T.G.Lin. Many others researchers from the Soviet Union and Russia made a significant contribution to the development of this direction: R.Z. Valiev, Y.D. Vishnyakov, S.D. Volkov, O.A. Kaybishev, V.A. Likhachev, V.E. Panin, V.V. Rybin, T.D. Shermergor et al. Physically based approach requires deep understanding of the internal mechanisms and processes that accompany thermomechanical effects caused by inelastic deformation at different scale levels. The important one for the microstructure formation and mechanical properties of finished products obtained by thermomechanical processing methods is the process of recrystallization. At that point in this article provides an review of the existing theories of recrystallization nucleation mechanisms. Basic physical mechanisms of nucleation recrystallized grains are classified: 1) the mechanism, based on the classical theory of fluctuations, proposed by J.E.Burke and D.Turnbull; 2) R.W. Cahn’s mechanism of nucleation and growth subgrains polycrystal, formed as a result of the process polygonization; 3) P.A. Beck’s and P.R. Sperry’s mechanism grain boundary migration, initially present in the polycrystal - strain induced boundary migration (SIBM); 4) the mechanism of nucleation and growth of new grains as a result of coalescence subgrains (H.Hu, J.C.M.Li, H.Fujita ). Analysis of existing models describing the inelastic deformation at high temperatures demonstrates the need for consideration and inclusion in the models description of physical mechanisms of high-temperature processes accompanying plastic deformation.