Alloying Component Adjustment And Mechanical Properties Research Of TA15 Titanium Alloy EB Welding Joint

As a kind of nearαtitanium, TA15 titanium alloy could be used in aircraft to produce the bulkheads and wall panels, which are served in high temperature or under complex stresses. Electron beam welding (EBW), which is reputed as the high energy processing technology in the 21st century, is perfectly suitable to weld the high thickness titanium frameworks on airplanes, for the manufacturing efficiency could be improved dozens of times and the gas sensitive titanium could get effectual protection in the welding machine vacuum. However, the application of EBW on the high thickness framework manufacture has been restricted by the dispersive fatigue life showed in before test. Finding a way to reduce the dispersing of fatigue life has become an extremely important problem for engineers.Changing of mechanical properties with the chemical component content in EB welding joints was studied in this research. The way to adjust chemical content in the welding seam is inserting pure titanium in the TA15 titanium alloy butt joint, and then applying different welding seam width which could influence on the ratio of base metal and the filler metal.The initial work is studying on the way EB welding parameters worked on the welding seam shapes, and a serial of welding seam with parallel weld junction and different welding width were obtained in this part of work. Energy dispersive spectroscopy (EDS) shows that chemistries could distribute uniformly in the welding seam with proper welding parameters, and the content of element could also be effectively adjusted. Metallographic microscope reveals that TA15 EB welded metal is the basket-weave structure. Insert pure metal results in a more sharply and fine texture.Results of mechanical testing indicate that the hardness obviously declined with 30.0%, impact toughness was considerable increased with 66.2%, without changing on strength and plasticity by insert pure titanium in TA15 titanium alloy butt joint. The most impressive result is that the standard deviation of fatigue life changed from 0.555 to 0.298, which means the dispersing of fatigue life was reduced by 46.3%. So the results certificated that decreasing alloying chemical content in welding seam is a feasible and effective way to reducing hardness and improving toughness of the EB welding joints, also shown a positive influence on reducing the dispersing of fatigue life.