АНАЛИЗ ФАЗОВО-СТРУКТУРНЫХ ПРЕВРАЩЕНИЙ ПРИ ОХЛАЖДЕНИИ СТАЛЕЙ С УЧЕТОМ ВОЗНИКАЮЩИХ ДЕФОРМАЦИЙ И НАПРЯЖЕНИЙ

Abstract

The aim of the work is to study the phase-structural transformations during cooling of carbon and low-alloy steels, taking into account the resulting structural deformations and stresses. Low-alloyed steels with different content of alloying elements - chromium, molybdenum, nickel and steel, micro-alloyed with vanadium were chosen as the object of research. The dilatograms of steel samples were used to find the relative expansion of the steel sample before the start of austenite phase transformation (DA) and the relative expansion of the steel sample during austenite phase transformation (DFТ), which are associated with the relative elongation of the sample through a constant factor K. The parameter DA allows you to find structural stresses that arise in supercooled austenite steel in the presence of a temperature gradient. The parameter DFТ characterizes the stresses created by the phase transformation of austenite. As a result of the performed regression analysis, dependences were obtained that link the chemical composition of the steel, its cooling rate, and the parameters DА and DFТ. The analysis of phase-structural transformations during the cooling of the steel with the occurring deformations and stresses. An empirical relationship has been established between the temperatures of the beginning and end of the phase transformation of austenite in steel, the physicochemical parameters d and Zy, the cooling rate, and the deformation parameters when the austenite is cooled DA and the phase transformation DFТ. Confirmed the adequacy of the constructed equations. The obtained regression equations make it possible to calculate the deformation parameters DA and DFТ and critical points of the steel Ac1 and Ac3.