Performance Of Eletron-beam Welded TC11 Jionts

The performance of aerospace vehicles have become increasingly demanding with the continuous progress of science and technology. There are new challenges in aerospace materials and the process technology. The connection technology effectively losing weight, the new materials of light weight and super-strength have become the urgent objective in the process of developing and applying materials. TC11 titanium alloy has widely used in light weight and reliable structure, such as drum of engine, compressor dish, blade, aircraft structures and so on. As one of the developed high-energy beam machining methods among various welding process, the electron beam welding technology is an effective connectivity method for aviation aircraft component. TC11 titanium alloy joints by electron-beam welding method are the research objects in the present work. The TC11 alloy joints have been investigated in terms of microstructure, micro-hardness distribution and room-temperature pre-tension deformation behavior. Moreover, we have measured the performances of the welded joints and base metal including high and low cycle fatigues. The results provide data support for the application and dissemination of TC11 titanium alloy and electron beam welding technology in aerospace field. The following conclusions have been obtained:Acicular martensite microstructure formed in the region of welding joint bond improved the hardness of joints. The In-situ tensile results showed that both localization and fracture position happened at the field near the side of base metal in the process of tensile strain. The base metal part yields before fusion area. Deformation of fusion area depended on the strain-hardening degree of base metal, so increasing ability of alloy's strain-hardening were expected to improve overall performance of the joints.S-N andε-N curves were obtained through high cycle fatigue and low cycle fatigue of TC11 electron beam welding joints and base metal. The fatigue property of welding joints was similar to that of base metal and joints cracked in the base metal zone. The fatigue cracks initiated on the surface of specimens. Fracture were cleavage and quasi-cleavage facets. Three fatigue experiments of pure weld specimens, pure base metal and welding joints of gauge segment as weld fusion zone were achieved. Residual strain accumulation in the circulation process of welding joints was observed. At high stress levels and plastic deformation of joints accumulated in base metal zone. The relative strength index based on stress fatigue was: weld fusion zone>heat-affected zone>base metal zone.The performance of electron beam welding joint was not less than that of base metal in tensile, durable, high and low cycle fatigue properties.