Effect of microstructure on high cycle fatigue behavior of Ti-20Zr-6.5Al-4V alloy

Abstract Room temperature fatigue behavior of Ti-20Zr-6.5Al-4V alloy containing equiaxed and lamellar microstructures is investigated. It is found that microstructures significantly affect high cycle fatigue strength. The fatigue strength for equiaxed microstructure at 10 7 cycles is around 575 MPa, which is lower than that for lamellar microstructure (775 MPa). Opposite scenario is observed at high stress level, especially above 825 MPa. A large scatter in fatigue life for lamellar microstructure is attributed to different crack initiation sites. For both types of microstructures, the pile-up of dislocations in α side of α/β interfaces provides preferable crack nucleation sites due to localized strain. Based on the results, effect of microstructure on high cycle fatigue properties is discussed.