In the paper to be submitted the notions of plastic flow localization are outlined. It is shown that a particular kind of localized plasticity pattern corresponds to a given stage of deformation hardening. In the course of plastic flow development a changeover in the types of localization patterns occurs. It is found that the emergent patterns are manifestations of the autowave nature of plastic flow localization process, each pattern corresponding to a definite type of autowave. The most intriguing localization pattern corresponds to a phase autowave which forms at the stage of linear work hardening. The following characteristics of phase autowave have been determined experimentally: propagation velocity and dispersion dependence of wavelength. Moreover, elastic-plastic strain relation is introduced which relates the elastic and plastic properties of the deforming medium. It is shown that the characteristics of autowaves follow from this relation.