Chen Zelin, Dong Zihao, Liu Chang, Dai Yajun, He Chao
Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan Province, Sichuan University, Chengdu 610105, China.
MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
Materials (Basel). 2022 Aug 23;15(17):5806. doi: 10.3390/ma15175806.
As nickel-based alloys are more and more widely used in engineering fields for bearing cyclic loadings, it is necessary to study their very-high-cycle fatigue (VHCF) properties. In this paper, the fatigue properties of nickel-based alloy 625 were investigated using an ultrasonic fatigue test apparatus. The fracture microscopy shows that around the crack initiation site there are two characteristic zones, a rough area (RA) and a fine granular area (FGA). Inclusions caused the interior fatigue crack initiation, and the coalescence of neighboring micro cracks was strongly influenced by the local microstructure, resulting in the RA morphology. Subsequently, the contact and compressing of the crack surfaces contributed to the formation of the FGA. Finally, the stress intensity factors of the RA and FGA were quantitatively evaluated for further discussion of the crack initiation and propagation processes.
由于镍基合金在承受循环载荷的工程领域中应用越来越广泛，因此有必要研究其超高周疲劳（VHCF）性能。本文采用超声疲劳试验装置研究了镍基合金625的疲劳性能。断口显微镜观察表明，在裂纹萌生部位周围有两个特征区域，即粗糙区域（RA）和细晶区域（FGA）。夹杂物导致内部疲劳裂纹萌生，相邻微裂纹的合并受局部微观结构的强烈影响，从而形成了RA形态。随后，裂纹表面的接触和挤压促成了FGA的形成。最后，对RA和FGA的应力强度因子进行了定量评估，以便进一步讨论裂纹萌生和扩展过程。
