Study on the fatigue crack growth rates of Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy with basket-weave microstructure

In the present paper, the fatigue crack growth behavior of Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy (Ti-55511) with different basket-weave microstructure features prepared by quasi-β forging and subsequent double annealing treatments are studied. The results show that the fatigue crack growth rates (FCGR) for five microstructures of Ti-55511 alloy vary obviously at low stress intensity factor range levels and then tend to be similar at high stress intensity factor range levels. According to analyses, the difference of the crack deflection effect caused by different basket-weave features is responsible for above phenomenon. It׳s found that the α platelet length and thickness are two critical basket-weave features influencing the crack deflection effect of Ti-55511 alloy. The long and thick α platelets are most favorable to deflecting the main crack and increasing the crack path tortuosity, which can obviously improve the fatigue crack growth resistance. In addition, at the end of the article, a generalized Paris model based on tensile properties is established for Ti-55511 alloy. Results show that this model can fairly describe the FCGR for Ti-55511 alloy when tested at a stress ratio of 0.1.