The wheel-rail contact is an open system contact, which is subjected to various environmental conditions, such as temperature, humidity, water, and even leaves. All these environmental factors influence wheel-rail wear. Classical wheel-rail wear has been extensively studied under dry and clean conditions previously. However, with changes in environmental conditions, the wear rate and wear mechanism can change. This paper reviews recent contributions to wheel-rail wear with a special focus on the influence of environmental conditions. The main part includes the basics of wheel-rail wear, experimental methodology, wear and rolling contact fatigue (RCF), and some measures to counter these degradation mechanisms.

Surface damages on rail became severe with the increase in the axle load and speed. Laser cladding was used to repair the local damages on rail surfaces to ensure the service performance and prolong the life of rails. In the present study, five types of cladding materials (304, 314, 2Cr13, 316L, and 434L) were clad at a small part (trapezoidal shape) of the rail disc to simulate the defected rail in the field. Vickers hardness tester, optical microscopy (OM), scanning electron microscopy (SEM), and electron-dispersive X-ray spectroscopy (EDS) were employed to investigate the service properties of the repaired rail discs. Results indicated that all these five clad rail discs had lower wear-rates than the unclad rail disc. The wear-rates decreased with the increase in the initial hardness of the clad layer. Cracks with large angles mainly propagated along the boundary at the front edge, while at the rear edge, the crack morphology was closely related to the hardness of clad layer. 434L would induce the minimum wear loss and the modest rolling contact fatigue (RCF) of the repaired rail disc, which could be the potential cladding material for repairing the damaged rail.

With a subscale rolling-sliding apparatus, the objective of this study is to explore the adhesion and rolling contact fatigue characteristics of wheel/rail rollers with sanding under water condition. Sanding improves adhesion coefficient but aggravates the surface damage of wheel and rail materials. With the particle diameter and feed rate increasing, the adhesion coefficient is further improved. However, the surface damage (spalling and pits) becomes severer as well as the surface roughness. Note that pitting is a special damage type when sanding is used to improve the adhesion. Big pits and fatigue cracks appear on subsurface under larger particle diameter and feed rate conditions. Severe cracks initiate from big pits and develop into material to a depth, which results in bulk material breaking.

Based on the grinding target profile of the rail and the grinding capacity of a single grinding stone, a numerical calculation method for rail grinding patterns that includes grinding angle and grinding power of each grinding stone of the GMC96 rail grinding train was designed and established. By means of this numerical method, the grinding pattern of each grinding pass was optimized and the rail head profile after grinding was calculated. Furthermore, a method for the evaluation of the grinding quality is provided. The results indicate that in multipass rail grinding, a sequence of grinding passes – where the greatest grinding effort is applied on the earlier passes, with the last pass applying reducing levels of grinding effort – produces the highest conformance to the target grinding profile. For example, when rail grinding is planned for two passes, applying 60% of the total grinding effort on the first pass and 40% on the second pass decreases the final grinding error by 7.3%.

A three-dimensional finite element model of rail grinding was established to explore the effects of grinding passes and grinding direction on the material removal behaviour of grinding rails during the grinding process. The results indicate that as the number of grinding passes increases, a decrease in the grinding force reduces both the amount of removed rail material and the surface roughness. There is a decrease in the grinding ratio caused by the increase in the wear on the grinding wheel and the decreased removal of the rail material. When the grinding direction changes, the wear of the grinding wheel decreases, which is contrary to the increasing trend of the amount of removed rail material, the grinding ratio, the surface roughness and the grinding force.

This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology and microstructural analyses, it revealed that the rolling contact fatigue wear mechanism played a significant role under the low slip ratio, but the dominant wear mechanism transferred to the abrasive wear at the high slip ratio. Meanwhile, the bainitic steel specifically presented worse wear resistance under the abrasive wear mode. Compared with the influence of a slip ratio, the increase in contact stress led to severer plastic flows and contributed to the propagation of cracks. In addition, the contact stress and slip ratio had the opposite effect on the friction coefficient, that is, the friction coefficient of bainitic steels behaved the inverse proportion with the contact stress, but positive proportion with the slip ratio. At last, the increase in slip ratio had more significant effect on the reduction of retained austenite (RA) than the enlargement of contact stress due to the fact that the RA would probably be removed before the martensitic transformation occurred under the abrasive wear mechanism.