A model describing the behavior of elastic–plastic medium with account of kinetics of dislocations has been developed. A method for determining kinetic parameters of the model is described. The model allows analyzing the mechanisms of deformation behavior of metallic materials on the basis of the obtained information on evolution of the average grain size, misorientations between grains, concentration of deformation-induced vacancies, average dislocation density, as well as the dislocation density in grain boundaries and interiors, forest dislocations and density of mobile dislocations depending on the strain degree. The developed model is applied to analyze mechanisms of deformation behavior in ultrafine-grained Ti Grade 4 produced by equal channel angular pressing – conform scheme.