(1. 宝鸡文理学院 机械工程学院，宝鸡 721013；
2. 贵州大学 材料与冶金学院，贵阳 550025)
摘 要: 基于断口学理论、借助SEM分析技术，分析高强韧Ti-55531合金片层和双态组织在不同应力幅下的高周疲劳断口形貌特征，揭示应力幅和组织因素对该合金高周疲劳裂纹萌生的协同作用机制，阐明组织因素对合金疲劳裂纹扩展的影响规律。结果显示：应力幅大小对片层组织的疲劳裂纹萌生行为有显著影响，但对双态组织影响较小。在疲劳裂纹扩展前期，片层的裂纹扩展速率大于双态的；但在裂纹扩展中后期，双态的裂纹扩展速率反而更高。
关键字: Ti-55531合金；高周疲劳；疲劳裂纹萌生；疲劳裂纹扩展；断口形貌
（1. Department of Mechanical and Electrical Engineering, Baoji University of Arts and Sciences, Baoji 721004, China;
2. College of Materials and Metallurgy, Guizhou University, Guiyang 550025, China）
Abstract:The high cycle fatigue(HCF) fracture morphological properties of high strength and toughness Ti-55531 alloy with LM and BM under different stress amplitude were analyzed by SEM based on the base fractography theory, the comprehensive influential mechanism of stress amplitude and microstructure factors on fatigue crack initiation were revealed, and the rule that microstructures affecting the fatigue crack propagation were illuminated. The results indicate that stress amplitude greatly affects the HCF primary crack initiation site of LM, while has a little effect on BM. The fatigue crack growth rate of LM is larger than that of BM during the crack propagation region with low speed. However, the crack growth rate of LM is lower than that of BM during crack propagation regions with high speed.
Key words: Ti-55531 alloy; high cycle fatigue; fatigue crack initiation; fatigue crack propagation; fracture morphology
