Hu Yongtao, Chen Yao, He Chao, Liu Yongjie, Wang Qingyuan, Wang Chong
Failure Mechanics and Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province, Sichuan University, Chengdu 610207, China.
MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
Materials (Basel). 2020 Oct 28;13(21):4820. doi: 10.3390/ma13214820.
Effect of microstructure on the crack initiation and early propagation mechanism in the very high cycle fatigue (VHCF) regime was studied in 316L stainless steel (316L SS) by atomic force microscope (AFM) and electron back scattered diffraction (EBSD). The results show that small fatigue cracks initiate from the slip band near the grain boundaries (GBs) or the twin boundaries (TBs). Early crack propagation along or cross the slip band is strongly influenced by the local microstructure such as grain size, orientation, and boundary. Besides, the gathered slip bands (SBs) are presented side by side with the damage grains of the run-out specimen. Finally, it is found that dislocations can either pass through the TBs, or be arrested at the TBs.
通过原子力显微镜（AFM）和电子背散射衍射（EBSD）研究了微观结构对316L不锈钢（316L SS）在超高周疲劳（VHCF）状态下裂纹萌生和早期扩展机制的影响。结果表明，小疲劳裂纹从晶界（GBs）或孪晶界（TBs）附近的滑移带萌生。沿滑移带或穿过滑移带的早期裂纹扩展受到局部微观结构的强烈影响，如晶粒尺寸、取向和边界。此外，聚集的滑移带（SBs）与疲劳试验失效试样的损伤晶粒并排出现。最后发现，位错既可以穿过孪晶界，也可以在孪晶界处受阻。
