Pashinskaya E.G.
Physical-mechanical principles of structure refinement by the combined plastic deformation. – Donetsk: press “Weber” (Donetsk division), 2009. – 352 p.
The work is devoted to the creation of a scientific physical-technological basis for structure and property evolution in metallic materials of BCC and FCC crystal lattice subjected to a combined plastic deformation by shear (torsion). It involves the development of concepts of controlled structure and physical-mechanical characteristics changing under influence of combined normal and shear stresses that resulted in competitive development of fragmentation and relaxation processes.
Data are given on studies of energy relaxation and dissipation processes in metallic materials subjected to a combined plastic deformation with shear and on the influence of the latter on structure transformation. It is shown that a combined loading with shear results in high specific values of the dissipated energy and the influence of stressed-state scheme on the behavior of material is connected with difference in the value of energy redistributed by the material during the deformation. This results in a periodic accumulation of the energy followed by release through rearrangement of the ensemble of defects to a state of higher ordering.
It is shown that the processes of structure formation developing under a combined loading with shear are notable for the effective rearrangement of defect structure and activation of the relaxation processes just in the course of deformation. As a consequence, during the deformation, the density of crystallattice defects is increasing slower than under comparable degrees of deformation in the absence of shear.
Peculiarities of nanostructure formation under a combined plastic deformation by twist pressing have been studied. Peculiarities of the structure have ensured high plastic characteristics with high enough strength properties conserved.
A new method for the processing of metals has been proposed – the rolling with shear which is based on phenomenological-theory principles. It has been found that the deformation by such a scheme results in a considerable fragmentation and stimulates the recrystallization developing during the deformation. It is shown that deformation according to the above scheme forms fine recrystallized grains with small quantity of defects in grain body. Under the pilotproduction conditions, high values of strength and plasticity for industrial pure copper, aluminum alloy (2L39), low- and high-carbon steels have been attained. The materials produced by rolling with shear are shown to be characterized by a high plasticity reserve.
It has been determined that peculiarities of the structure formed under a combined deformation with shear are inherited under subsequent deformation and thermal influences. A successive cold deformation of metals is accompanied by the growth of strength properties with high plastic characteristics preserved. Activation of cementite spheroidization process during the thermal treatment of high-carbon steels after the rolling with shear has been noted. The revealed regularities are related to the effect of structural heredity of the metal, deformed by the combined plastic deformation with shear.
