针对目前金属材料疲劳裂纹扩展门槛值测定中存在的测定周期长、试样尺寸较大以及单位周次裂纹扩展长度测量误差较大等问题, 采用扫描电镜原位观察技术测定了TC4钛合金的疲劳裂纹扩展门槛值, 即通过扫描电镜对裂纹扩展长度的实时精确测定实现快速获得材料的疲劳裂纹扩展门槛值。结果表明: 利用该方法测得的TC4钛合金的疲劳裂纹扩展门槛值与已报道的数据基本一致, 并且具有快速简便等优点, 表明该方法可以用来测定金属材料的疲劳裂纹扩展门槛值。

Aimed at solving the problems in the determination of fatigue crack growth threshold of metal materials, such as longer testing period, larger specimen dimension and lower measurement accuracy in crack propagation length, an in-situ observation method was used to determine the fatigue crack growth threshold of TC4 titanium alloy. By this scanning electron microscope in-situ observation technology, the measurement accuracy of crack growth length could be improved and the testing period could be shortened. The results show that the fatigue crack growth threshold of TC4 titanium alloy tested by this method was consistent with the data that had been reported, and the measuring time was much less compared with the traditional method. This implied that this method was an effective method in determination of fatigue crack growth threshold and can be used as an ideal method to determine the fatigue crack growth threshold of metal materials.