The parameters of localization patterns emerging at the linear stage of work hardening are discussed in the frame of autowave concept. The stress-strain diagrams have been plotted for the test samples of metals exposed to active loading. It is found that the product of phase autowave velocity and length has the same order of magnitude as the product of elastic wave rate and the lattice constant of the respective metal; hence, this quantity can be regarded as elastic-plastic invariant. The invariant is found to vary in a regular manner with the shear modulus, modulus of dilatation and interplanar spacing. The data obtained for elements of one and the same period of Mendeleev’s table of elements are found to vary monotonically; however, after changing over to the next period, a jump-wise variation in the data would occur. It can thus be concluded that the elastic-plastic invariant is a dominant characteristic of plasticity; the nature of the invariant is related to the lattice properties and the phonon dens...