Investigation on the effect of rotational speed on rolling wear and damage behaviors of wheel/rail materials

The objective of this study is to investigate the effects of rotational speed on rolling wear and damage behaviors of wheel/rail materials using a rolling-sliding wear testing apparatus. The results indicate that, with the rotational speed increasing, the surface hardness of rail roller remains unchanged while the increase of surface hardness of wheel roller declines resulting in a decrease of wheel/rail hardness ratio. The wear loss of wheel roller increases while the wear loss of rail roller declines with increasing rotational speed. The worn surface of rail roller exhibits peeling and spalling damage. Fatigue cracks and adhesive wear are dominating for the worn surface of wheel roller. Furthermore, with the speed increasing the fatigue damage lightens and adhesive wear worsens for the wheel roller. Fatigue cracks of wheel rollers grow along with soft ferrite lines in plastic deformation area. Cracks of rail rollers tend to turn towards the worn surface. There are visible branch cracks and multilayer cracks on the surface of wheel/rail rollers. Branch cracks of wheel rollers are longer than that of rail roller, and the interlayer material of multilayer cracks is easy to break. Wear debris of wheel/rail rollers is composed of Fe2O3 and martensite. The size of debris with flakes structure decreases and the martensite content increases with the rotational speed increasing. (C) 2015 Elsevier B.V. All rights reserved.