Study on crack growth and fatigue life in TC6 titanium alloy by integrated phase proportion and grain size modeling

In this paper, a theoretical model is developed to reveal the crack growth and fatigue life in polycrystalline alloys with dual-phase microstructure. The present quantitative analysis proves that the grain size and phase proportion can efficaciously affect the crack growth and fatigue life. The dislocations emitted from the crack tip and penetrated three types of grain boundaries (GBs) under cyclic shear stress. According the different boundaries, we obtained the calculation of three kinds of critical penetration stress (τ_cr) and dislocation stress (τ₁). Moreover, it can be worked out the crack growth and fatigue life. As the results suggest that the fatigue crack growth reduces with decreases of grain size and increases of minor phases proportion (X_β). Comparison of fatigue life prediction, we derived the fatigue fracture characteristics. In a word, the results offer awareness to improve the mechanical properties in dual-phase titanium alloy by optimizing the microstructures.