Numerical Simulation Of Fusion-brazed Butt Joint Between Aluminum Alloy And Galvanized Steel With Different Thickness By Arc-assisted Laser

In recent years, due to the energy problem and vehicle emissions problem increasingly serious, the automotive lightweighting received around the world more and more attention.Integration of aluminum/steel structure, automobile, shipbuilding, electric power in areas such as the development of energy saving and emission reduction requirements, has the good economic efficiency.But aluminum/steel dissimilar metal of high quality, high efficiency is a difficult problem in the field of welding.Arc assisted laser welding technology, which can effectively use arc heat source, under the condition of small laser power to obtain larger wetting spreading and interface reaction, significantly improve the spreading width of joint, at the same time, cooling time also reduces the tendency of welding deformation, welding process to achieve high efficiency, high quality.So the aluminum/steel dissimilar metal arc assisted laser welding has important scientific significance and application prospects.Adopt the method of precast powder coating, the use of auxiliary laser arc welding method, the range of the thickness of the aluminum/galvanized steel butt weld brazing for numerical simulation analysis.Using ANSYS finite element software, the establishment of gauss heat source model to simulate TIG arc and three-dimensional cone misalignment combination of heat source model to simulate the laser heat source model, the temperature field and stress field coupling analysis, get the welding temperature field and residual stress in the process of distribution;Analysis arc assisted laser welding heat input, arc current, the process parameters such as heat source center spacing of molten brazing temperature field and residual stress, the effect of simultaneous contrast analysis of the single laser beam welding and arc auxiliary to the same laser welding parameters on weld of the influence of the temperature field and residual stress field.Temperature field analysis results show that the combination of heat source temperature gradient than single heat source is wide, the temperature drop is relatively slow, prolong the time of solidification of molten pool, to weld the node reaching the highest temperature of local time also gradually extended, two ways of temperature field simulation results are in good agreement with the experimental results.Residual stress field analysis results show that the cooling delay misalignment combination of heat, the stress value is small, the weld area is at zero stress state;And cooling after welding, the weld area equivalent stress is lesser, workpiece deformation is relatively small.Single heat source and the bending deformation after welding, two head bent arched, maximize steel side welding deformation is tensile stress, gradually transition to the compressive stress at both ends, aluminum alloy under the influence of welding deformation presents corresponding deformation, but the stress and deformation is small, stress did not exceed the yield strength.A slight deviation simulated stress value and the measured values after the error produces on the one hand is to weld shelved for a long time with stress release;Followed by the measurement accuracy is poorer;Moreover the established mathematical physical model needs further improvement.Numerical analysis results show that the arc assisted laser butt weld brazing than single laser welding has a better effect.The simulation analysis could be used to optimize laser brazing aluminum/steel secondary arc welding process and to analyze its mechanism provides the basis.