A TWIN-DISC STUDY OF THE ROLE OF THE SURFACE QUALITY ACHIEVED BY GRINDING ON THE WEAR RESISTANCE AND ROLLING CONTACT FATIGUE BEHAVIOR OF WHEEL/RAIL PAIRS

The tribological behavior of twin-disc samples prepared under laboratory-controlled grinding operations was studied. A laboratory grinding device was designed and validated to produce similar results to those found in the field in terms of surface quality and presence of white etching layer (WEL). The test samples were evaluated in a twin-disc machine under dry and lubricated conditions. The results showed that the surface finishing parameters and the microstructure change greatly depending on the surface preparation procedure, and that such changes affect the tribological response of the samples. The wear rates of the tribological tests for the different rail surface qualities showed a reduction of 47.4% for the lubricated tests and 7.3% for the dry tests when the surfaces of the rail specimens were finished by grinding. This only applied when the WEL thickness was less than 4 µm.