Study on fatigue wear competition mechanism and microstructure evolution on the surface of a bainitic steel rail

The wear and fatigue competition mechanism of a bainitic rail steel was studied through rolling contact fatigue test. Results showed that the damage process could be divided into initial (before 2.0 x 105 cycles), middle (around 2.0 x 105 cycles) and late (after 2.0 x 105 cycles) stages, with the dominant damage mechanisms of wear, wear and fatigue, and fatigue in each respectively. With increasing rolling cycles, the retained austenite transformation played an important role in achieving dynamic equilibrium between wear and fatigue. Moreover, the untransformed retained austenite could release crack tip stress and effectively control the excessive propagation of fatigue cracks.