Twin disc assessment of wear regime transitions and rolling contact fatigue in R400HT – E8 pairs

Twin disc tests were carried out to evaluate the wear resistance and Rolling Contact Fatigue (RCF) of premium R400HT rail samples in contact with E8 wheel samples. The wear rate and friction coefficient were correlated with the frictional work expended at the contact interface (the Tgamma approach). Accelerated RCF tests were also carried out on the premium R400HT rail and the results were compared to those obtained for standard R260 rail. The wear rates of rail samples were consistently lower than those reported in the literature for other contacting pairs in which the rail material studied is softer than R400HT. Also, the energy needed for the transition from the moderate to severe wear regime significantly increased for the hardened rail. Fatigue cracks were shallower for R400HT when compared with standard rail material. Hardened rails also showed lower mean spacing between fatigue cracks. This new information can be used to improve wear simulations of wheels and rails by using more realistic wear equations.