Influence of the Initial State of Samples From Steel 20 on the Structural-Phase Condition to the Stable Zone Localization of Macrodeformation

Abstract

One of the most important tasks of technical diagnostics and examination of industrial safety is the problem of assessing the residual life of long-running technical devices of hazardous production facilities. The paper presents the results of the study of the structural-phase state in a stable zone of localization of macrostrains, depending on the initial state of samples from steel 20. The samples were investigated without exploitation, after operation without destruction and with destruction. The samples were stretched at the same speed until a stable zone of strain localization appeared, after which the loading was stopped. The connection is established between the processes of localization of macrostrains and the evolution of the substructural state for steel 20. It has been established that the mechanism of localization of macrodeformations is the achievement of critical values of a fragmented substructure, in other words, according to the theory of evolution of substructural transformations, a bifurcation point occurs when the % fragmented substructure prevails. The critical values of dislocation density are established, which lead to a change in the type of dislocation substructure for equipment made of steel 20.