| In this paper, manufacturing technologies are studied to achieve lighter body structure of railway vehicles, to meet the project needs of train high-speed operation. key technology is researched on the large-scale hollow extrusion profiles 6005A-T6 aluminum alloy tandem welding technology in the process of engineering applications. Tandem welding robot welding process is used for 6005A-T6 aluminum alloy required by manufacturing high-speed electric multiple units (EMUs) project of national "Eleventh Five-Years Plan" and the "long-term railway network plan", and after welding experiments, material properties is studied so as to provide theory and technical support for practical engineering applications. By adjusting the welding parameters, compared single-wire and tandem welding process characteristics, and optimized out the 6005A-T6 aluminum alloy tandem welding process parameters. Using of modern quality control testing equipments, analyzed on the welding joints with tandem welding procedure and single-wire procedure respectively, through X-ray nondestructive testing, microstructures analyzing, mechanical properties checking and tension fracture appearance. Studied the welding parameters, welding materials, and investigated effects on the weld microstructure and properties and strengthening mechanism by pre-wire and post-wire electrical parameters of tandem welding process. Comprehensive evaluated welding forming feasibility of 6005A-T6 aluminum alloy with tandem welding procedure applied to high-speed EMUs car-body.The result shows, when use pre-wire high current and small voltage, post-wire a small current, large voltage, tandem welding procedure is qualified with the following advantages: higher welding speed, better weld shaping, compacter joint structure, smaller crystal grain, Mg2Si strengthening phase precipitation, better mechanical properties of weld joints, and it is suitable for the mass auto-welding manufacturing high-speed EMUs car-body. |
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