Study on Fatigue Crack Propagation of TC4-DT Electron Beam Welded Joint

The microstructure,fatigue crack propagation and fatigue fractographs in the fusion zone(FZ)of the TC4-DT titanium alloy electron beam welded(EBW)joint were studied in this paper.The results indicate that the microstructure in FZ is characterized by bulky aciculate marten site,and heat affection zone(HAZ),the microstructure is composed ofα′marten site+lamellarαandβ.It shows a transition from FZ to base material.The fatigue crack propagation rate is closely relative with the FZ microstructure.The lamellar base material has a better resistance to the fatigue crack propagation the fusion zone.