Numerical Simulation And Experimental Study On Deep Penetration Laser Welding Of Dissimilar Metal Aluminum/Steel

Energy saving, environmental protection and safety are the future development direction of automobile industry. Automobile lightening is one of the important technologies to meet these requirements. The main measures to achieve lightweight of automobile at present is the use of a large number of high-strength and light-weight materials such as aluminum alloys, magnesium alloys, plastic and composite materials,which trigger the extensive application of connection technology of dissimilar metals in automobile industry, so it requires us to master connection technology of dissimilar metal such as steel and aluminum. But there is a huge difference in physical and chemical properties between steel and aluminum, which brings technical problems to weld them.In this paper, the difficulties and problems existed in welding dissimilar metals steel and aluminum are mentioned first. Then, the welding temperature field is simulated to optimize the welding parameters. Finally, experiments of deep penetration laser welding of dissimilar metals steel and aluminum has carried out.First of all, the mechanism, characteristic and application of laser welding technology is summarized, the research status on welding of dissimilar metals steel / aluminum and computer simulation is discussed.Secondly, the experimental platform for laser welding dissimilar metals steel and aluminum is set up, and the main welding parameters used in the following experiments are determined.Thirdly, numerical simulation of laser welding dissimilar metals steel/ aluminum is carried out. ANSYS software is used to simulate the welding temperature field, and the temperature distribution is obtained after such steps as geometric modeling, meshing, loading heat source, determining boundary conditions,and post-processing. Based on the obtained cloud picture of temperature distribution at different time and the heat cycling curve at the nodes on the specimen surface, the effects of such welding parameters as laser power and welding speed on the temperature distribution are analyzed. The simulation results are in good agreement with the experimental results, which can verify the correctness of the simulation results.Finally, experiments of butt welding dissimilar metals steel / aluminum using a fiber laser is carried out, through which the optimum welding parameters are determined. Compared the appearance of the welds obtained by laser welding with or without Ni adding, the effect of adding alloying element Ni on the weld performance is studied. By using single factor method, the effects of such parameters as laser power, welding speed and defocus on welding quality are investigated. The metallographic structure of the welds is observed, and the tensile strength of the welds is tested. At last,the main welding defects existed commonly in laser welding of Dissimilar metals steel/aluminum are analyzed, and the corresponding methods for preventing them are put forward.