| The technology of superplastic forming and diffusion bonding (SPF/DB) has made the development for multi-sheet structure manufacturing of titanium alloy. However, there is a huge space for development in aviation and aerospace fields. So, the researches on superplasticity of existing materials and technologies of other bonding methods combined with superplastic forming have extremely important significance. To develope the multi-layer structure of aluminum alloys can reduce manufacturing cost and weight under meeting the performance requirements of modern aircraft. However, the obstinate oxide film of aluminum alloy leads to that diffusion bonding of the alloy is not easy. This problem exists so that the multi-layer structure of aluminum alloy by SPF/DB becomes more difficult.Al-Mg based 5083 Al alloy has shown broad applications in aerospace, aviation, shipping and other departments for its special characteristics, such as low price, moderate strength, good corrosion resistance and high formability with moderate superplasticity. In this paper, the superplasticity and its deformation mechanism, foming properties, laser beam welding performance of 5083 Al alloy were sdudied in detail. The good forming and welding process parameters were determined by experiments. These provide a reliable basis for the development and application of multi-layer structure of alumimum alloys using the technique of laser beam welding + superplastic forming (LBW+SPF). To this end, this paper has been focused on the sdudies as following:The microstructure with uniform equiaxed fine gain (average size of 3μm) was obtained using the thermo-mechanical processing (TMP) for the 5083 Al alloy plate. The microstructure evolution of the fine-grained 5083 Al alloy has been firstly investigated at annealing temperatures of 150～300℃. The results indicate that the suitable annealing temperature is about 200℃in terms of Organization superplasticity. Uniaxial tensile test was carried out at a temperature range of 500～570℃and a strain rate range of 4.17×10-4～1.0×10-2 s-1. Maximum tensile elongation 530% was obtained at 550℃and strain rate 4.17×10-4s-1, at which maximum strain rate sensitivity index m of 0.68 was attained. The cavities and fracture were observed during uniaxial tensile deformation of the alloy by scanning electronic microscopy (SEM). It indicated that linkage of cavities in large region would induce failure of the material. Moreover, presence of liquid phase at grain boundary also influenced superplastic deformation and behavior of cavities.The effect of temperature of female die, deep drawing speeds, blankholder gap and lubricating condition on non-isothermal deep technology of fine-grained 5083 Al alloy was studied under temperature range of 200～300℃. Experimental results show that, fine-grained 5083 Al alloy sheets have good deep drawing formability when temperature of female die is higher than 250℃. When the temperature of female die was 275℃, the limiting drawing ratio (LDR) of the material reached maximum 2.9. Under the optimum female-temperature and different punch speed, the influences of strain rate on the non-isothermal deep drawing process of fine-grained 5083 Al alloy is a little. When the punch speed is equal or lesser than 2mm/min, the deep drawing will be well.The laser full penetration welding without filler of fine-grained 5083 Al alloy sheets is investigated with 3kW CO2 laser, butt and lap joints were used in two forms. Butt weld penetration test results show that, the welding surface with high quality is obtained under appropriate laser power and welding speed. The profile of microhardness traverse across the weld exhibits like W shape and that the heat affected zone (HAZ) has serious softening. The results of high temperature tension show that the tensile strength of welded joint is greater than the base metal, which is the side of fractures. Optimal relative height of 0.59 of the free bulging specimen is obtained at 500℃. This result shows that laser butt-welding sheets of fine-grained 5083 Al alloy possess good high temperature formability. The thickness of 1.1mm and 0.9mm for the fine-grained 5083 Al alloy sheets in lap welding penetration test results show that, the profile of microhardness traverse across the weld exhibits like W shape and that the heat affected zone has serious softening. The results of tensile test at room temperature show that the tensile strength of welded joint is 186Mpa, which is about 64% of a general 5083 base metal. And the tensile strength of the welded specimen is about 91% that of the base metal at 500℃. Multi-sheet structures of an aluminum alloy were fabricated through laser beam welding combined with superplastic forming technique. The novel welding design and bonding have been developed to improve the formation quality of the structure for the alumimum alloy. Forming process parameters are: forming temperature is 500℃, forming time is 45min, and forming pressure is 1.2MPa.The distribution in thickness within the formed structure and bonding conditions between face- and core-sheets were investigated. It reveals homogeneous deformation and well-bonding property of the structure. This verifies the feasibility of the processing procedures for the multi-sheet structures of an aluminum alloy.
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