Improvement in the wear resistance of a hypereutectoid rail via heat treatment

Abstract The rail, as the most important component in railways, needs to be routinely checked to maintain proper service conditions to prevent catastrophic accidents by any premature failure of the rail. The severe plastic deformation of rails due to cyclic wheel/rail contact forces forms a superficial deformed layer, referred to as the white etching layer, because of cementite decomposition and the formation of the carbon-supersaturated nanostructured ferrite phase. This supersaturated superficial layer is highly prone to the initiation and propagation of rolling contact fatigue cracks. However, it has been observed that transition carbides and cementite can precipitate when the first and third stages of tempering starts at approximately 150 and 400 °C, respectively, due to carbon ejection from the body-centered tetragonal structure. A controlled laboratory heat treatment was conducted on a used hypereutectoid rail at 200 and 500 °C. Then, the wear resistances of the heat-treated samples were compared with the as-received rail sample using pin-on-disc testing. A significant increase in the wear resistance of the sample treated at 200 °C confirmed the improvement in the wear resistance of used pearlitic rails, which is a great interest for railway industries.