The fatigue and fracture properties of titanium alloy bars play an important role in determining the service life of alloys. The fatigue and fracture mechanism of titanium alloy bars and their relationship with various metallurgical factors have been studied at home and abroad for many years. Due to the complexity of the problem itself, the dispersion of the initial test data, some substantive issues are still not very clear, the point of view is not completely unified, here tungsten boat manufacturer only introduces some representative conclusions.

Like other materials, the fatigue life of titanium alloy bars depends on the rate of crack initiation and crack propagation. According to the study of pure titanium, most fatigue cracks within the slip zone and the twin boundary surface nuclear, but for this ai Ti - 6, 4 v type alloy, under the condition of low stress, a and b phase interface is the weakest link, just in a high stress level, slip band endogenous nuclear risk increased significantly, improve test temperature has a similar effect, in order to improve the fatigue performance, to a 10 b type of titanium alloy rods, usually get fine equiaxed hope a 10 b group, and b phase in free state, in order to reduce a/b phase interface area. In addition, the slip of fine grains is uniform and the slip free distance is short, which can reduce the stress concentration caused by dislocation plug. At the same time, fine crystals also have a greater constraint on twins. On the contrary, the fatigue strength of the coarse crystal Weinianite structure is low because the fatigue crack nucleates easily.

In the case of notch and stress concentration, the influence of grain size decreases, because the fatigue life is mainly determined by the crack growth rate, and the experimental results of pure titanium from tungsten boat manufacturer show that the crack growth rate is not closely related to the grain size.