Autowave Mechanics of Plastic Flow

Abstract

The notions of plastic flow localization are reviewed here. It have been shown that each type 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. The types of localization patterns are limited to a total of four pattern types. A correspondence has been set up between the emergent localization pattern and the respective flow stage. It is found that the localization patterns are manifestations of the autowave nature of plastic flow localization process, with each pattern type corresponding to a definite type of autowave. Propagation velocity, dispersion and grain size dependence of wavelength have been determined experimentally for the phase autowave. An elastic-plastic strain invariant has also been introduced to relate the elastic and plastic properties of the deforming medium. It is found that the autowave’s characteristics follow directly from the latter invariant. A hypothetic quasi-particle has been introduced which correlates with the localized plasticity autowave; the probable properties of the quasi-particle have been estimated. Taking the quasi-particle approach, the characteristics of the plastic flow localization process are considered herein.

Autowave description of the temperature effect during deformation of FCC metals

“…The last provision needs to be clarified. As was established earlier [1], at the stage of linear strain hardening, the propagation speed of the phase autowave of localized deformation is given by the relation V aw ≈ /θ, in which the experimentally determined constant ≈ 5 • 10 −7 m/s [1,2]. Then, for the strain hardening coefficient, we can write…”

“…Experimental studies and analysis of the kinetics of the solids plastic deformation development [1,2] shown that the essence of this process is the generation and regular evolution of a small set of autowave modes of macroscopically localized plastic flow, transforming into each other when the law of strain hardening changes during deformation. Autowave modes form the pattern of localized plasticity observed on the surface.…”

“…The dispersion law for autowaves of localized plasticity has the quadratic form ω aw (k) ∝ 1 + k 2 , where ω aw = 2π/T t is the autowave frequency, and k = 2π/λ is the wavenumber [1]. This type of dispersion law indicates a significant nonlinearity of plastic flow processes.…”

“…The main regularities of autowave processes of plastic flow are consequences of the elastic-plastic deformation invariant, which (for a phase autowave of localized plasticity) has the form [1,2]:…”

“…The aim of this paper was to analyze the temperature effect on the autowave mechanism of plasticity and to search for the nature of the relationship between the temperature behavior of the material plasticity characteristics and the parameters of autowave deformation processes at the stages of parabolic and linear strain hardening. It is known that stationary dissipative structures are generated on the first of them, and phase autowaves of localized plastic flow on the second one [1,2]. In both cases, the deformable medium turns out to be stratified into alternating deformable and non-deformable zones.…”