Irreversibility of Plastic Deformation Processes in Metals

The process of plastic deformation of steel DC04 is considered a complex, non-linear, irreversible, and self-organized process. An analysis of the irreversibility of the stress-strain time series makes it possible to identify characteristic areas of (quasi-)elastic, plastic deformation, and necking. The last two sections are the most informative. The region of inelastic deformation is characterized by collective self-organized processes of dislocation structures transformation, turning into pore formation and, ultimately, the formation of microcracks and a general crack as the cause of sample failure. Measures for the quantitative assessment of the irreversibility of the deformation process are proposed. Such measures as multiscale asymmetry, Poincaré, network-, and permutation-based measures are found to be especially informative measures, which can be used not only to classify the stages of plastic deformation but also can be applied as a precursor of the material irreversible destruction process.