Effects of Wheel Materials on Wear and Fatigue Damage Behaviors of Wheels/Rails

Abstract

Rolling contact fatigue (RCF) and wear are inevitable problems for wheels and rails. Recently, increasing vehicle speeds and axle loads have led to the need for an increase in the hardness of the wheel. In this article, the RCF and wear characteristics of normal rails and heat-treated rails due to an increase in the wheel hardness were evaluated through experiments. As the hardness of the wheel increased, different types of damage occurred for each kind of rail. Pitting and cracks occurred in the normal rails, and corrugation through the delamination wear mechanism occurred in the heat-treated rails. The heat-treated rail exhibited increased hardness and resistance to wear as the lamellar spacing of the metal structure became smaller due to heat treatment. However, it showed delamination wear because the depth of plastic deformation is shallow, the fracture toughness is low, and the crack growth rate is fast. In addition, the steady-state wear behavior was found in which the hardness is increased by the work-hardening effect and the wear rate is decreased accordingly and the wear rate remains constant after a certain cycle. Therefore, the initial hardness as well as the work hardening effect should be taken into consideration in order to evaluate the wear characteristics of wheels and rails.