RAIL LUBRICATION: THE RELATIONSHIP OF WEAR AND FATIGUE

Truly effective lubrication of the wheel-rail interfaces has been shown to reduce both wear and metal flow to a much greater extent than previously had been considered possible. In addition, unforeseen benefits in reduction of corrugation development are achievable. However, in many cases a metallurgy-lubrication interaction is observed such that premium rail metallurgies benefit far less than does standard carbon rail. One explanation for this behavior may be found in the manner in which the octahedral fracture strain of rail materials varies with the ratio of contact pressure to in-surface shear stress. The enormous benefits of truly effective lubrication in reducing wear, flow, and corrugation occurrence are offset significantly by the tendency of railhead fatigue failure to become the dominant mode of rail replacement. A three-dimensional fatigue model has been employed to show that the use of rail grinding and of stronger and metallurgically cleaner rail steels can be expected to delay the damage done by fatigue processes.