%A LIU Tian-xiang, YANG Mao-sheng, LI Shao-hong %T Fatigue crack initiation and propagation behavior of high temperature carburized bearing steel during rotary bending %0 Journal Article %D 2021 %J Iron and Steel %R 10.13228/j.boyuan.issn0449-749x.20210092 %P 136-143 %V 56 %N 9 %U {http://www.chinamet.cn/Jweb_gt/CN/abstract/article_153092.shtml} %8 2021-09-15 %X In order to improve the service life of aviation bearing, with the help of QBWP-10000X rotary bending fatigue testing machine,the rotary bending fatigue properties and crack initiation and propagation behavior of high temperature carburized bearing steel were studied. The results show that the median fatigue strength of the steel reaches 913.3 MPa. A large amount of M23C6 and a small amount of M6C carbides in the effective carburized layer significantly improve the surface hardness of the test steel. Different carbon concentrations in the carburized layer lead to martensite transformation successively and form 408 MPa surface compressive stress,which further improves the fatigue property of the steel. The fatigue cracks mainly originate from surface defects and subsurface carbides,accounting for 71.4% and 28.6% respectively. The results show that the characteristic size of crack initiation and the bearing stress have a significant effect on the stress intensity factor and the number of cycles. The shape of deep furrow directly affects the number of cycles due to the stress concentration. The larger the characteristic size of carbide under the same loading stress,the lower the number of cycles. After the crack initiation,it propagates rapidly along the carbide boundary of carburized layer and slowly to the core. Finally,quasi cleavage and ductile mixed fracture occur near the edge of the specimen on the opposite side of the fatigue source.