Abstract: With early failed high manganese steel and bainite steel crossings on actual railway line as the study object, the microstructure changes in the worn surface layer of the crossings are investigated by using metallurgical microscopy, SEM, TEM, MÖssbauer spectroscopy. In the mean time the failure mechanisms of the crossings are analyzed．The research results indicate that the microstructure in the worn surfaces of both crossings changes to nanocrystalline, and the carbon atoms get together in the worn surface of the high manganese steel crossing in service. The failure mechanism of the high manganese steel crossing is wear, collapse deformation and fatigue spalling, however, the failure mechanism of the bainite steel crossing is wear, hydrogen induced brittle spalling. Accordingly, some new methods are put forward to increase the lifetime of the crossings and enhance the safety of the railway system.

Key words: Bainite steel, Crossing, Failure, High manganese steel