Microstructure and fatigue crack growth behavior of electron beam welded joints for TC4-DT titanium alloy

The microstructure of electron beam welded joints of TC4-DT titanium alloy was analyzed by optical microscope, and the microstructure characteristics of different position in the joint were also analyzed.The crack propagation path and its growth rate were investigated on the joint samples, which the initial crack appeared at different location of the welded joints.Based on the microstructure characteristics of the welded joints, the influences of the weld microstructure on fatigue crack growth behavior were discussed.The results show that there are differences in the microstructure for electron beam welded joint along penetration depth.The fatigue crack propagation resistances of the weld fusion zone and heat affected zone were higher than that of the base metal, and the crack propagation path of the joints gradually tended to base metal zone.The influence of the crack propagation path offsets on crack growth rate was finally discussed in the paper.