Study On Weld Welding And Welding Process Of Spray Forming 7055 Aluminum Alloy

The studies focuses on MIG welding process and welded joint properties for spray forming 7055 aluminum in this paper. Spray forming,as an advanced technique of rapid solidification,the materials prepared by this technology have various advantages of rapid solidification characters such as fine grain, homogeneous and little macrosegregation. Therefore, the technology of spray forming widely used in the preparation of super-high strength aluminum alloy, and the development advantage is obvious. Nowadays, the studies of microstructure and properties of 7055 aluminum alloy prepared by spray forming has been investigated largely,but the research works on weldability and welding technology is little. And the studies on the welding and welding joint organization performance of being used the technology of MIG welding for super high strength aluminum alloy hardly especially adopted. Therefore a reasonable assessment of super-high strength aluminum alloy MIG welding and welding joint organization performance has a certain research value.MIG welding was employed to 7055 plate prepared by spray forming. Microstructure and mechanical property of the joints were analyzed by optical, scanning electron microscopy, XRD and other testing methods.It was found that: the use of welded joints 4043 higher hardness than the hardness of the 5356,5183 wire, 5183 wire welded joint strength is highest.By results of microstructure analyses, the welding joint contains three parts include weld zone、fusion zone and heat affected zone. Welding parameters have big impact on the joint bone state. Grain size grows in HAZ,a large amount of alloying element was segregated. The results of XRD analysis indicated that the amount of η(Mg Zn2) phase decreased sharply and a great many of T phase formed. 043 welded joint fracture morphology for the intergranular fracture. 5183,5356 welded joint fracture morphology of cleavage fracture by SEM analysisAfter the heat treatment of the welding joints,the tensile strength 、hardness and the elongation of the joint made by MIG increased drastically,segregation in the weld zone have been eliminated. Fracture form by the intergranular fracture became the intergranular fracture and transgranular fracture mixed fracture morphology; the fatigue fracture to cleavage fracture.