Research On Deformation Behavior And Microstructure Of Magnetic Pulse Joining Of 5A02-0Cr18Ni9 Tubes

Since the aluminum alloy is widely used in aerospace, automotive and other fields, joining dissimilar metals has become a hot topic. Currently, the use of magnetic pulse joining technology(MPJ) has gained welded joints between aluminum and steel, and the requirements of lightweight parts have been achieved, while report about aluminum and stainless steel is rare. In this dissertation, 5A02 aluminum alloy and 0Cr18Ni9 stainless steel magnetic pulse joining technology was explored by a method of combining numerical simulation and process tests, and the impact of main process parameters on the joining effect is focused on. Finally a reasonable range of process parameters is obtainedBased on finite element analysis software ANSYS, MPJ technology for numerical dissimilar metals tube such as aluminum and stainless steel has been analyzed using numerical simulation, and a loose coupling method is selected. A two dimensional axial electro-magnetic field model was established in the Multiphysics module to analyze the variation of magnetic force. In the LS-DYNA module, a tube deformation analysis model is established which uses a plastic material model associated with strain rate. The effect of process parameters such as the overlapping position, the discharge voltage and the radial gap between two pipe on MPJ process collision angle and speed during the guide process tests are analyzed. And a reasonable range of process parameters as a reference for process test is obtained.MPJ process test for 5A02 and 0Cr18Ni9 is completed, and influence of process parameters such as the discharge voltage, the radial gap between pipes and the lap location between field shaper and pipe on the quality of welded joint is studied by the peel test. Based on this study, the optimum parameters of MPJ for 5A02-0Cr18Ni9 have been identified.The mechanical property of the 5A02/0Cr18Ni9 MPJ joints which is obtained under different discharge energy, radial clearance condition is analyzed. Test results show that the bonding strength of the joint which is obtained in the appropriate process parameters achieves 48.1MPa.Microstructure of the 5A02/0Cr18Ni9 MPJ joints interface is observed by SEM and found that 5A02/0Cr18Ni9 interface includes two morphologies: with and without transition zone. Then, interfacial transition zone is further analyzed by TEM and EDS. The results show that the transition zone mainly contains amorphous phase consisting of Al and Fe while the dispersed particle contains Fe. The steel side near the transition zone appears equated fine grain, and the aluminum side appears some huge grains with sub-grain structure. What’s more, the micro hardness of joints interface is tested using a Nano hardness tester, and got hardness variation in the interface. Also, explanation which increases the hardness of the near interface is given.