Mig Welding Of Az31 Magnesium Alloy Weld Shape And Numerical Simulation Of The Stress Field

As more and more widely used magnesium alloy, the research of its connection technology is very necessary. MIG welding is one of important methods of magnesium alloys welding, although the MIG welding of magnesium alloy complex heat transfer process spends a lot of money and manpower in experimental methods , it is difficult to obtain important information, the numerical simulation of magnesium alloy MIG welding is an important research tool.Firstly, the 6mm thick AZ31 magnesium alloy plate was welded with MIG welding in a series of various welding parameters, then various weld shape and size (weld width and weld penetration) are observed and measured, the measurement results were compared with the simulation results. Secondly, magnesium alloys specimens three-dimensional model of MIG welding was established by ANSYS software to simulate welding temperature field of the 6mm thick AZ31 magnesium alloy plate. In analogue computation, heat - structure coupling function of ANSYS software was used to calculate welding temperature field, then, the calculated results was taken as the load of structure analysis to carry out the calculation of welding stress field. Finally, the simulation results after post-processing were given thermal cycling curve and stress distribution curve of weldment in different locations and different times, the calculated results was compared with measured results.Through comparison analysis on technology experiment results and numerical simulation results, we obtained the conclusion that the weld had a smooth look under the welding current 150A, welding voltage 24V, welding speed for 8mm / s conditions, so they were taken for the best welding parameters. Meanwhile,It found that the weld width and weld penetration increased with increasing welding current and welding voltage, decreased with increasing the welding speed. The variation law was basically the same as technology experiment; the results showed that the maximum temperature and cooling speed was good accordance with numerical simulation results. The simulated results on stress field showed that longitudinal residual stress of weld seams was almost pull pressure; residual stress was the biggest in the middle of weld joints; the longitudinal residual stress decreased gradually at vertical weld seams direction; the vertical residual stress changed into compressive stress away from the weld direction; In the weld transverse residual stress near the tensile stress, also had both compressive stress; along the weld direction, the first part of the transverse welding residual stress was more, and showed a decreasing trend along the weld direction; vertical weld direction, residual stress transverse of welding plate fluctuated around zero. The results showed that the established finite element model was close to the actual situation, and had strong reference value.