The Research Of Magnesium Alloy Sheet Welding Forming

On the basis of the DE- GMAW welding, to a certain improvement, this paper designed a model for copper alloy electrode welding torch to replace DE- GMAW welding system bypass TIG welding gun, and do the AZ31 B magnesium alloy sheet welding experiment.First of all, use the single variable method, keep the other welding parameters unchanged and change a welding parameter to do the welding experiments, then analysis the influence of the parameters on appearance of weld, by contrast, obtain the optimal values of the parameters. Use this method to do experiments in turn of the welding voltage, bypass, welding current, welding gun geometry position speed. Analysis of weld and weld size, obtain the different welding parameters on weld forming and the effect of weld size and optimal values of different welding parameters and good weld forming.Then, by means of optical microscope to observe the microstructure of weld. Found that when the welding parameters is small, the weld fusion zone contains some columnar crystal, grain size is larger, grain interior and grain boundary has much precipitated phase. With the increase of welding parameters, the columnar crystal in the weld fusion zone gradually disappear, grain size and precipitated phase decreases.Finally, use the microhardness meter to test the microhardness of weld. Found that the microhardness of weld bond is least, the parent metal area is bigger, weld center is biggest, and near the center line the microhardness is biggest. With the increase of welding parameters, the microhardness of weld fusion zone and the central increase gradually, but the microhardness of fusion area is always less than the parent metal area. Use the universal testing machine to do tensile experiment of sample. Found that the weld tensile strength increases with the increase of welding parameter, but always less than the tens ile strength of parent metal, and breakup is located in the weld fusion zone.After analysis, finally obtain the welding parameters are: welding voltage U = 20 V, total current I = 220 A, bypass current Ibp = 140 A, welding speed V = 2.9 m/min, end of the wire to the workpiece distance d = 3 mm, to the wire at the end of the copper electrode distance d1 = 2 mm, copper electrode end to artifacts from d2 = 4 mm, MIG welding torch conductive mouth to artifacts from d3 = 18 mm, MIG welding torch and the bypass torch Angle theta = 55 °, argon gas flow is 25 l/min.