Addressing perceptions regarding the influence of relative hardness on wheel/rail performance

Abstract

An age-old debate amongst railway practitioners has revolved around the potential effects of increased wheel and/or rail steel hardness on corresponding damage rates. In specific, whether raising the hardness of one partner will have a deleterious impact on the wear rates of the other. This paper addresses that question through two methods.• Laboratory and field evidence on performance of rail/wheel pairs of differing hardness is reviewed.• A survey was sent to railway practitioners around the world to collect perceptions on how relative hardness might influence wheel-rail performance. These perspectives are then addressed using principles of contact mechanics, fracture mechanics and general material characteristics.Through the review of available evidence, and application of fundamental principles, it can be seen that increasing the hardness of one partner in the wheel-rail system is not expected to have a direct or causal effect on the wear rates experienced by the other. However, increasing the hardness of one or both partners does motivate increasing care in maintaining wheel and rail profiles, along with other maintenance considerations.