The processes of inelastic deformation of shape memory alloys (SMA) are determined taking place in their phase and structural transformations. In this paper we propose a one-dimensional micromechanical model deformation process SPF of structural transformations, by which is meant the reorientation process (detwinning) martensite, phenomenological generalization of this model to three dimensions, as well as defining the relations describing the nonlinear deformation of SMA in the active processes of direct martensitic transformation and reorientation of martensite . The results given by the model are compared with experimental data.