Evolution of microstructure and mechanical properties of the high-speed train bearing under different service periods.

The microstructure and mechanical properties of high-speed train bearing are significantly influenced by the harsh service environment during the long-term service process, which is crucial for the safety and service life of bearing. In this paper, the outer ring of high-speed train bearing is taken as the research object. The microstructure of the outer ring under different service periods was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) combined with electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The mechanical properties were measured by the MTS testing machine and microhardness tester. The evolution of microstructure and mechanical properties of the high-speed train bearing outer rings under different service periods was investigated by comparative analysis. The results show that, with the increase of the service period, the bainite in bearing outer ring become coarser, the number of acicular carbides increases, and size of microcracks increases. Moreover, the dislocation density and microhardness near the inner-surface of the outer ring increases slightly. However, both yield strength and ultimate strength decrease with the increase of the service period. [ABSTRACT FROM AUTHOR]