Toughness Evaluation Method Research Of2219Aluminum Alloy Welded Joints

With the upgrading of the rocket tank material, aluminum alloy2219has gradually become themain choice of tank materials.The use of aluminum alloy2219create a space for the application ofnew welding processes.Many welding methods have been applied to tank welding, such as friction stirwelding, variable polarity plasma welding, vacuum electron beam welding. For a long time, thewelded performance of aluminum alloy tanks primarily evaluate the toughness of welded jointsthrough the tensile strength and elongation. The toughness of welded joints lack scientific evaluationall the time. In this paper, the toughness assessment method aluminum alloy2219welded joints undervarious process conditions has been started research.In this paper, the static tensile test of aluminum alloy2219welded joints has been done. Afterdealing with the experimental data, this paper obtains tensile strength yield strength, elongation andstress-strain curve area that characterize toughness of aluminum alloy2219welded joints undervarious process conditions.The surface morphology of aluminum alloy2219welded joints is analyzed form both macrolevel and micro level with the help of scanning electron microscope. With a macro view, the fracturesurfaces present three areas that are fiber zone, radiation zone and shear zone. The fractures underdifferent process conditions have different areas of each zone. With a micro view, it found that brokenforms of the test are mainly quasi-cleavage fracture and dimple fracture.The3D numerical information of fracture surfaces is obtained by3D reconstruction platform thatperform three-dimensional reconstruction of SEM images. Fractal dimension of each fracture isobtained using cubic covering method that calculate3D surfaces of each specimen fracture.By analysing static tensile test results of2219aluminum alloy welded joints, the influence ofvarious process parameters on mechanical properties is obtained, such as strength, ductility,toughness.The indicator of evaluating toughness is obtained by dealing with the area of stress-strain curvethat characterize the strength of toughness. The relationship models of different welding methods areestablished between toughness index and fractal dimension through the analysis of test data.