中文摘要：

分别采用常规和超声疲劳的试验方法,结合断裂力学理论以及FRASTA仿真,开展了GCr15钢超高周疲劳破坏行为的研究。结果表明,根据裂纹萌生位置的不同,疲劳破坏分为表面和内部破坏两种,其中内部破坏伴有granular bright facet（GBF）现象的产生,整个内部裂纹具有＂Fish-eye＂形貌特征。材料的疲劳S-N曲线呈现持续下降的趋势,ΔKGBF（4～4.2MPa·m1/2）是控制内部裂纹扩展的临界参数,超声疲劳试验提高了材料的疲劳强度,高强度钢的超高周疲劳行为的研究应采用常规试验为主,超声为辅的试验方法。

英文摘要：

The very high cycle fatigue fracture behavior of GCr15 steel was researched by the method of conventional fatigue test and ultrasonic fatigue test respectively, combining with fracture mechanics theory and the simulation of FRASTA. The test results show that fatigue fracture is divided into the surface fracture mode and interior fracture mode according to the difference of crack initiation position. The phenomenon of granular bright facet（GBF） appears in the interior fracture mode, and the entire interior crack takes on typical appearance characteristics of ＂Fisheye＂. The fatigue S-N curve of GCr15 steel indicates that the fatigue life is continuous descending with increasing stress. The stress intensity factor amplitude △KG8F （4 ~ 4.2MPa.m^12 ） is the critical parameter of controlling interior crack propagation. Higher fatigue strength of GCr15 steel is observed in the ultrasonic fatigue test. The conventional fatigue test as the main test method and the ultrasonic fatigue test as a supplemental method is recommended for the study of the very high cycle fatigue fracture behavior of high strength steel.