Wear of driving versus driven discs in a twin disc rolling-sliding test

Theoretically, the stress states in wheel and rail will be different during braking (rail driving) and acceleration (wheel driving), and this will lead to different wear mechanisms and rates in each. In order to reveal the wear mechanism of wheel and rail materials under these different conditions, existing twin disc work on the wear and damage of wheel and rail where they were both considered was analysed. Some trends emerged, but there was little consistency in the way the different tests had been conducted. To avoid hardness/microstructure variables, new tests were then outlined where the same material pairs were used. The results indicated that the wear rate of the driving disc (faster one) was significantly higher than that of the driven one. The driven discs mainly experienced fatigue and abrasion mechanisms, while the driving one more typically suffered tribo-chemical reactions and fatigue. Finally, the potential causes for the difference in wear behaviours between the driving and driven discs were identified: the hardness; the formation mechanism of metal debris; the stress state; the material properties and the varying work conditions. This work has provided some important new data on wear trends at different driving conditions that will be helpful in the subsequent modelling of wheel and rail wear.