Effect of normal load on the wear and rolling contact fatigue behaviour of AAR class B wheel against R350HT rail in a twin disc simulator

Abstract

The normal load at the wheel-rail contact interface plays a significant role in wear and rolling contact fatigue (RCF) performance of both wheel and rail steels. In recent years, there has been an increase in axle loads due to increased demand for railway services. This study investigated the effect of normal load on the wear and RCF behaviour of the AAR class B wheel versus R350HT rail using a twin disc wear simulator. The mass loss, surface damage and depth of deformation were used to assess wear and RCF, respectively. From the mass loss results, wear maps were obtained to identify different wear regimes being mild, severe and catastrophic at different contact loads and slip ratios. Scanning electron microscopy was also used to assess the surface damage of wheel and rail steels in order to identify the wear regimes with surface cracking and delamination being observed at higher contact loads indicating severe and catastrophic wear. Furthermore, the RCF crack density was found to be higher on specimens evaluated at higher normal loads with more cracks evident and crack branching forming.