Study of sliding wear of the wheel flange - Rail gauge corner contact conditions: Comparative between cast and forged steel wheel materials

Abstract

Wheel-rail contact is in the spotlight of Railway Engineering and its specific conditions are highly dependent on railroad characteristics, such as load, speed, track design and materials used, among others. To understand wear mechanisms for typical contact conditions of a railroad with many tight curves, sliding-wear tests were performed on pin-on-disc configuration, without lubrication, at various sliding speeds and constant normal load. The pins and discs were machined from rail and wheel materials, respectively. The worn volume of the samples were obtained by optical microscopy and 3D profilometry and the wear mechanisms were analyzed using a scanning electron microscope. The results indicate a higher friction coefficient for tests at a speed of 0.9 m/s, at about 0.8, when compared to the values obtained at 0.1 m/s – between 0.5 and 0.6. The wear severity of both pins and discs were up to four times higher in the tests carried out with a sliding speed of 0.1 m/s. Comparing the different materials of the discs, the wear of pins and discs were considerably greater in tribosystems with forged steel discs – about two to three times the wear. The wear mechanisms observed were predominantly of plastic nature, with occurrence of ploughing and adhesion of oxidized materials on the surface of pins and discs.