Effect of third mediums on the formation and evolution of rail corrugation

In order to study the influence of third mediums on the formation and evolution behaviours of rail corrugation, two series of rolling-sliding tests were performed. Firstly, tests under the dry and different third mediums (oil, grease, water, friction modifier and windblown sand) conditions were conducted to study the influence of third mediums on the formation of rail corrugation. Secondly, rail rollers were first rolled under the dry condition until a stable rail corrugation was formed. Then, water and friction modifier were added into the wheel-rail interface to investigate the role of third mediums on the evolution behaviours of rail corrugation. The results indicated that third mediums had a significant influence on the wheel-rail damage and the formation and evolution of rail corrugation. Compared with the dry condition, both the mass losses and the damage of rail rollers were alleviated under third mediums conditions. The continuous application of third mediums at the wheel-rail interface could alleviate the formation of rail corrugation significantly. When non-solid third mediums existed at the wheel-rail interface (oil, grease, water and friction modifier), no corrugation was observed. In the dynamic windblown sand environment, the corrugation was obviously slighter than that under the dry contact condition. After corrugation was formed on the rail roller, the application of water and friction modifier could alleviate the amplitude of rail corrugation. Furthermore, with the increase in the number of cycles, the amplitude of rail corrugation first increased and then remained nearly stable. Under the dry contact condition, the crack length in the trough was larger than that in the crest. When liquid third mediums were applied, the cracks at the crest were ground away. However, some liquid would enter into the pre-existed crack in the trough, resulting in the severe rolling contact fatigue damage of rail.