Rolling contact fatigue failure mechanism with the multi-scale analysis of BG801 high temperature bearing steel

With the development of the aviation industry, the operating conditions of aero-engine bearings have become increasingly severe. To improve the lifespan of bearings, a new type of high-temperature bearing steel BG801 has been produced. In this study, a ball-on-rod rolling contact fatigue (RCF) tester is used to examine the RCF damage evolution process and failure mechanism of BG801 bearing steel. The mechanical properties and organizational structure of BG801 bearing steel are characterized at the millimeter, micrometer, and nanometer scales. The damage evolution during the test is explored and the failure mechanism is analyzed. The research results show that the uniformly distributed refined M₇C₃ carbides and matric grains refinement produced in the subsurface layer during the carburizing process are the main factors that improve the anti-RCF performance of BG801 bearing steel. The RCF of BG801 bearing steel is caused by the interaction of the non-uniform distribution of subsurface M₇C₃ carbides, the existence of the second phase inside the M₇C₃ carbides, and the degradation of the mechanical properties of the matrix. This study provides an in-depth analysis of the RCF failure mechanism of BG801 bearing steel for the first time. The results provide data for the material's performance optimization and engineering applications.