中文摘要：

采用高周拉压疲劳试验,测试了片层Ti-55531合金的室温高周疲劳性能。利用TEM、SEM等分析检测方法,研究了近裂纹源区次生裂纹特征,以及显微组织均匀性对高周疲劳裂纹萌生的影响。结果发现：该片状Ti-55531合金室温高周疲劳强度σ-1（1×10^7）可达639 MPa。合金显微组织中含少量晶界α和大量10～50μm大小的组织不均匀区,疲劳变形时,晶界α处开裂或组织不均匀区内次生αs断裂、αs/βr界面处开裂等萌生微裂纹,促进合金的疲劳失效。

英文摘要：

The influence of microstructure homogeneity on crack initiation behavior under high-cycle fatigue（HCF） test at room temperature was studied in Ti-55531 alloy with lamellar microstructure by TEM and SEM. The results show that the HCF strength of Ti-55531 alloy could be as high as 639 MPa. However, a small amount of grain boundary（GB） α and a large number of inhomogeneous regions in microstructure significantly affect the HCF behavior of lamellar Ti-55531 alloy. Fatigue microcracks mainly initiate at interfaces between αs and βr phases owing to their different structures and properties. Moreover, a small amount of microcracks initiate at GB α and αsphases during fatigue.