Numerical Simulation On Temperature Distribution Of Cold Metal Transfer Joining Magnesium To Titanium Dissimilar Metals

Using the ABAQUS finite element software to simulate the Mg/Ti dissimilar metal CMT welding process, Mg/Ti dissimilar metal lap welding model were established. Temperature field and residual stresses filed of weld were simulated and analyzed. The simulated results were consistent witth experimental results.Firstly, Mg/Ti weld temperature field model were established. Using the element birth and death technology to consider the filling process of the weld, the variation of temperature field and the welding characteristic points thermal cycle curve were measured and analyzed. Variation of the temperature field and the microstructure of the feature point were compared at different wire feed speeds. The results show that the distributions of the temperature field are asymmetric at both magnesium and titanium sides. At the two points with the same distance from the weld center, temperature rises rapidly at the magnesium side specimen, a higher peak temperature at the Mg sheet is reached than that of the Ti sheet and the rate of decline is also fast. As the wire feed speed increases, the peak temperature becomes higher and reaches the molten temperature of titanium sheet, the amount of molten Ti increased yet, thus the better connection can be formed Mg-Ti joints.The residual stresses were analyzed by the thermal-force coupling analysis method. researched the residual stress when. According to the residual stress distribution at the wire speed of11.5m/min, the stress of middle weld metal is O, however, and the maximum stress of363MPa is located in the Ti sheet heat affected zone. The stress results of fixed position at different time presents that the transverse stress and the longitudinal stress of weld joint are changed from compression stress to tensile stress. The residual stress is asymmetric. The transverse stress reaches a peak in heat affected zone. The transverse stress at Ti side reaches192MPa and the transverse stress at Mg side reaches88MPa. Both sides of Mg-Ti welded joint longitudinal residual stress almost equal and reach220MPa. Because Mg alloy has greater thermal conductivities than Ti alloy, the deformation degree of Mg sheet is much greater than Ti sheet.In order to verify the simulated results, the residual stress and deformation at various boundary conditions were measured and analyzed. The results show that stress and deformation at coupling constraint boundary condition is coincident with the experimental results. Welding parameters affected welding deformation and stress, which showed that the deformation and residual stress of the Mg-Ti welded joint increase with increasing of heat input.