Research On Aluminum Based Material For Electron Beam 3D Printing And Its Forming Performance

With the maturation of additive manufacturing technology?also known as 3D printing?for metals,its application in aerospace and automobile industry has been greatly developed.However,the lack of research on the forming process of these materials is becoming the main limiting factor for the development of their additive manufacturing technology.In the present study,according to the research status of 3D printing aluminum alloys,three kinds of aluminum alloy welding wires,2319Al,4043Al and 4047Al,were selected for additive manufacturing through electron beam freeform fabrication?EBF³?,and the microstructures and mechanical properties of the printed samples were modified by heat treatment processes.For the printed 2319 Al,the average grain size in the printed sample was less than 10?m,containing primary Al₂Cu phases,fine particles,and coarse impurity phases.There are some tiny voids in the printed sample,and the sizes of the voids are about 5?15?m.The tensile properties of the printed sample are 161,174 and 167 MPa in the length,width and height directions.After a T6 treatment,the coarse phase were basically dissolved and some finer phases were re-precipitated,the size of viods are increased.Due to the dominant effect of dispersion strengthening,the mechanical properties of the sample were significantly improved,and the ultimate tensile strength of the sample in three directions was increased to 423,495,and421MPa,respectively.For the 4043Al and 4047Al,the printed samples contained some banded microstructures consisting of silicon particles and impurity phases.Two kinds of fine Si particles with equiaxed or rod-like morphologies were found in the as-printed samples.The tensile strength of the presented samples is similar in three directions:for the 4043Al,the strength is 120¹27MPa and the elongation is 12%³0%;for the 4047Al,the tensile strength is 151¹55 MPa and the elongation is 15%³0%.After heat treatment,the tensile strength of the samples decreased slightly,but their elongations increased significantly.Al-10Si and 5%TiB₂/Al-10Si wires were prepared by powder metallurgy,hot extrusion and drawing,with the aim to investigate the 3D printing property of the composite.The EBF³experiments were carried out in different processes,and the single and multi-pass printed samples were printed.Microstructure analysis shows that,due to the particles,appeared a lot of voids in composite materials.For the dense sample,the microstructure was composed of dendrite and equiaxed crystal,and its ultimate tensile strength is 135 MPa,which is close that of the hot pressed sample?147MPa?,and the elongation is 4.5%.