(北京航空材料研究院，北京 100095)
摘 要: 研究600 ℃不同应力集中系数(Kt)条件下TG6钛合金的高周疲劳性能，并用扫描电镜对疲劳断口形貌进行观察。结果表明：应力比(R)为0.1时，TG6合金光滑试样的疲劳极限为365 MPa，缺口试样的疲劳极限为220 MPa，表明该合金有敏感的缺口效应；光滑试样的疲劳裂纹源只有一个，出现在试样内部，缺口试样在试样表面有多个疲劳裂纹源；在疲劳裂纹扩展区可见明显疲劳条带和二次裂纹，随着裂纹扩展长度的增加，裂纹扩展速率加快，疲劳条带加宽；TG6合金疲劳断裂呈韧性断裂特征。
关键字: TG6钛合金；应力集中系数；高周疲劳；疲劳极限；疲劳断口形貌
（Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:The high cycle fatigue (HCF) of TG6 titanium alloy was investigated under the condition of different stress concentration factor (Kt) at 600 ℃. In addition, the fatigue fracture surfaces of the alloy were examined by scanning electron microscopy. The results show that the high cycle fatigue limit strength for the smooth specimens is 365 MPa, and that for the notched specimens is 220 MPa, indicating that the alloy has notch sensitivity. SEM fractography indicates that the smooth specimens have one inner-specimen initiation of fatigue cracks. However, the notched specimens have multiple initiations of fatigue cracks across the surface. In the domain of fatigue crack growth, fatigue striations and secondary cracks are distinctly visible. As the length of crack grows, the width of the fatigue striations increases. The fatigue fracture mode of TG6 titanium alloy shows a feature of ductile fracture.
Key words: TG6 titanium alloy; stress concentrating factor; high cycle fatigue; fatigue limit; fatigue fractography
