Study On The Forming Technology And Properties Of 2319 Aluminum Alloy Lattice Structure By Wire And Arc Additive Manufacture

Aluminum alloy lattice structures have extensive application in the aerospace field,due to the combinational advantages,such as light weight,high strength,heat insulation,shock absorption and noise reduction.However,the present methods have high requirements of material,and confront great difficulty in fabricating such kinds of complex structures;it limits the design freedom of material and structure for manufacturing lattice structures.Wire and arc additive manufacturing（WAAM）is an additive manufacturing technology that uses arc as a heating source and selects wire as additive material to manufacture complex components layer by layer.WAAM is suitable for the fabrication of any metal material and complex lattice structures.In the thesis,the fabrication process and properties of ER2319 aluminum alloy lattice structure by WAAM have been studied,and ER2319 the aluminum alloy lattice structure demonstration has been prepared.The effects of processing parameters by WAAM on the structural parameters（diameter and angle）of lattice struts were studied.The struts diameter can be controlled by adjusting the size and number of droplets,and the size of the droplet can be controlled by adjusting the current,voltage,and period within a pulse period..The struts with a diameter of no less than 2.50mm were manufactured by WAAM,and its relative error was less than 2.0%.The struts angle can be controlled by adjusting the inter-layer lift and offset of the arc torch.The angle of the strut was from 15°to 90°,and its relative error was below 4.0%.The manufacturing strategy of lattice structure by WAAM was formulated,and the aluminum alloy lattice structure demonstration was prepared,where compressive properties and microstructure were studied.According to the structural characteristics,the lattice structure has been divided into two parts:the strut part and the node part,and for each part respectively,corresponding manufacturing strategy was formulated.By controlling the lattice structure struts diameter and angle in accordance with manufacturing strategy,a pyramid lattice structure of 4×14×3 cells was manufactured according to additive manufacturing strategy.And the topological structure of each lattice unit was not much different from the theoretical model in terms of macroscopic morphology.The compressive strength of 2319 aluminium lattice structures was58.53MPa,which was low and required heat treatment.The microstructure presents a layered distribution,which is divided into two regions:inner-face and interface.In inner-face region,the microstructure was mainly equiaxed grains.In interface region,the microstructure of was not very regular,mainly dendritic crystals.The second phase wasθ-Al₂Cu phase,which was precipitated in eutectic structure withα-Al.At the same time,the acicular precipitationθ’is very low,leading to insufficient strength of the material.By using the method of orthogonal test,the influence of heat treatment process（including solid solution temperature,solution time,aging temperature and aging time）on the performance the organization of 2319 aluminum lattice structure has been researched,and obtained the best T6 heat treatment process specification:solid solution temperature is 530℃,the solid solution time is 60 min,aging temperature is 175℃,aging time is 24 h.Under the best heat treatment process,the compressive strength of2319 aluminium lattice structures was 76.08MPa,which increased by 30.0%in comparison with the compression strength of lattice structure before heat treatment.