Rolling Contact Fatigue and Wear Behavior of High-Performance Railway Wheel Steels Under Various Rolling-Sliding Contact Conditions

An experimental investigation was carried out to study and compare the response to cyclic loading of the high performance railway wheel steels ER8 EN13262 and SUPERLOS®. Rolling contact tests were performed with the same contact pressure, rolling speed and sliding/rolling ratio, varying the lubrication regime to simulate different climatic conditions. The samples, machined out of wheel rims at two depths within the re-profiling layer, were coupled with UIC 900A rail steel samples. The wear rates, friction coefficients and hardness were correlated with the deformation beneath the contact surface. The crack morphology was studied and the damage mechanisms were identified. The distribution of crack length and depth at the end of the dry tests was analysed to quantify the damage. The main difference between the steels lies in the response of the external samples to dry contact: SUPERLOS® is subjected to a higher wear and lower friction coefficient than ER8, this reduces the density of surface cracks that can propagate under wet contact conditions. The analysis of feedback data from in service wheels confirmed the experimental results.