Localization of Deformation in the Process of Large Plastic Deformations

Abstract

Experimental studies show that localization of plastic flow occurs both in quasi-static and dynamic deformations of metals. It leads to the formation of selected areas (lines, shear bands), in which the magnitude of plastic deformation and the density of crystal-lattice defects (dislocations) are several times higher than the values of these elements in the surrounding metal. Localization is a manifestation of the instability of plastic deformation, a consequence of the fact that in such areas of localized flow, for one reason or another, plastic deformation proceeds more easily than in the surrounding material. The formation of localization areas reduces the shear strength of metals; so, this effect should be taken into account when modelling the elastoplastic deformation of metals. In addition, the formation of areas with a high density of defects can initiate a change in the internal structure of the metal, e.g., the formation of new grain boundaries during intense plastic deformation. Therefore, the study of the mechanisms and conditions of localization of plastic flow is an urgent task of deformable-solid mechanics and is important both for numerical modelling of elastoplastic flows in metals and from the point of view of forecasting the structure and mechanical properties of deformed metal. Localization of plastic flow at low and moderate strain rates has been studied in detail in a number of works. At the same time, there is no common understanding of the mechanisms and specific features of the localization of plastic flow.

Keywords

• plastic deformation
• plastic flow
• microstructure
• mechanical properties
• martensite