Actual problems of hypereutectoid steel rails

For difficult operating conditions (high axle loads and speeds, temperature gradients, small radii of curvature, etc.), hypereutectoid steel rails (C ˃ 0.8 wt.%) are used, which have increased wear resistance and resistance to contact fatigue. This article provides an overview of the literature by foreign and domestic researchers on post-eutectoid steel rails, covering the main areas of production technology, heat treatment, and the influence of various factors on improving the performance of rails. The influence of chemical composition, heat treatment, and rolling modes on the formation of structural and phase states and operational properties of rails has been analyzed. Methods and techniques for laser surfacing of rails, lubrication of contact surfaces, mathematical models predicting the interplate distance taking into account changes in Si, C, V, Nb, Cr, and Mn, and mechanisms of wear, corrosion, and destruction of rails have been proposed. The research on the structure, phase composition, dislocation substructure, and properties of the head section of the differentiated-hardened 100-meter DT 400 IR rails with increased wear resistance and contact endurance has been analyzed. These rails are intended for use in straight sections of railway tracks with speeds up to 200 km/h and in curved sections of railway tracks without restrictions on load intensity after 187 million tons of traffic on the experimental ring of Russian Railways. The hierarchy of physical mechanisms of hardening at different distances (0.2–10 mm) from the rolling surface along the central axis and the radius of rounding of the cut is established. The results of patent search of technologies of production of the hypereutectoid rails and their hardening are presented. Methods of cooling, micro-alloying with rare-earth elements, reduction of the content of hydrogen, cementite grid are described. It is concluded that there is no systematic analysis of international and domestic experience on the problems of rails made of hypereutectoid steel.