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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。
The fatigue failure behavior of GCr15 steel under ultrahigh-cycle was studied by using conventional and ultrasonic fatigue test methods, combined with fracture mechanics theory and FRASTA simulation respectively. The results show that the fatigue failure is divided into two types according to the locations of initiation of cracks: the internal failure accompanied with the occurrence of granular bright facet (GBF), and the appearance of “Fish-eye” topography . The SN curve of the material shows a continuous decreasing trend. ΔKGBF (4 ~ 4.2MPa · m1 / 2) is the critical parameter to control the internal crack propagation. Ultrasonic fatigue test improves the fatigue strength of the material and the ultrahigh cycle fatigue behavior of high strength steel The research should be based on conventional tests, supplemented by ultrasound test method.