Fatigue Fracture Analysis of TA1 Electron Beam Welded Joint with a Thickness of 30 mm

In order to investigate the causes for fatigue fracture of the electron beam welding（EBW） joints,fatigue tests were conducted on joints welded by TA1 medium plates with 30 mm of thickness,and S-N curve and conditional fatigue limit were obtained.The macro and micro structures and mechanical properties of TA1 joints were investigated,and the fracture characteristics of the joints were obtained by combining fracture analysis of the fatigue specimens for the typical short-life joints.Test results show that electron beam welding（EBW） process can strengthen the weld seam and heat affected zone of TA1 joint,which makes the entire joint without obvious softening zone.The S-N curve data of TA1 electron beam welded joint conform the linear fitting law.The fitted fatigue limit value of 163 MPa is 48.7% of tensile strength of the joint,which conforms the general law of fatigue design of the metal structural parts.The main cause for the joint fracture is the existence of micron-sized welding pores,and the fatigue fracture for part of the joints is due to the existence of welding slag inclusion.