Patterns of changes in the plastic and deformation characteristics of rail steels alloyed with chromium in the temperature range of hot rolling

Abstract

Based on the set of experimental studies for chromium rail steels of grades E76KhF, E76KhSF and E90KhAF, the basic laws governing the influence of hot rolling temperature on ductility and the regularities of temperature and strain rate influence in the temperature range of hot rolling on plastic deformation resistance are determined and scientifically substantiated. It was shown that for E76KhF steel at deformation temperatures of 1050 °C, a sharp decrease in ductility occurs due to the presence of cementite-type carbides (Fe, Mn, Cr)3C at the grain boundaries. For rail steels with a lower chromium content, the indicated ductility drop is not observed. It was established that an increase in the deformation temperature of rail steel E76KhSF causes a decrease in deformation resistance, and an increase in the strain rate significantly reduces this indicator. Also the fact that the deformation resistance decreases with distance from the surface to the central zone of continuously cast billets is established, which is due to an increase in grain size. Based on the obtained data, a new mode of rail rolling was developed in the conditions of the rail and beam workshop of EVRAZ ZSMK JSC, the introduction of which allowed the quality of the rails to be significantly improved as well as the technical and economic indicators of their production with an economic effect of approximately 120 million rubles/year.