Study Of A-TIG Welding On AZ31B Magnesium Alloy

Because of the advantages of low density, high specific intensity and high specific rigidity, renewable, magnesium alloy has a broad prospect for development in the field of industry. At present, TIG welding technology is the most widely used in magnesium alloy connection application. Compared with the conventional TIG welding, which has the problems of poor melting depth, coarse grains and low productivity, a highly efficient A-TIG welding is getting more and more attention of people. It improves efficiency and increases the weld penetration by using the complex physical and chemical change of fluxes that occurred in the process of welding thermal cycle. Therefore, there are great potential in application and use of the use of A-TIG welding technology of magnesium alloys.On account of the magnesium alloy AZ31 B, this topic selects oxide, chloride and fluoride as the fluxes for A-TIG welding test. After coated with different fluxes, 5mm Surfacing welding were used respectively to study how fluxes works on the weld penetration, surface morphology and 2mm butt welding test were used respectively to study how fluxes works on the the welded joint microstructure and mechanical properties. The test results show that the fluxes selected in surfacing welding experiment has totally different effects on weld surface molding, but all the weld penetration can be increased, The weld surface forming coated oxide Al2O3, chloride Cd Cl2, fluoride Al F3 is relatively well; In the selected chloride, oxide, fluoride agents, the largest respectively is Cd Cl2, Al2O3, Al F3, the weld penetration depth can reach TIG weld penetration of 221%, 186%, 172%. In Butt welding experiment, active welding head strength is equivalent to ordinary TIG welding, The tensile strength of the welded joint can reach TIG welded point of 95.6%, 90.1% and 92.7%, and all the tensile specimens cracked in heat affected zone.The addition of fluxes make weld grain have grew up but has no effect on the composition of the weld phase, and the welding joint is still mixed fracture.On the basis of each single surfactant test results, the composite fluxes mixture formula design experiment was carried out by means of the uniform design method. Under the same condition of the welding parameters, the preparation of 28 kinds of formula was carried out by surfacing welding experiment, thus find out the optimal formula. And the better formula was chosen for the A-TIG welding experiment in search of the effect of the welding parameters and the amount of fluxes coating produced on the weld penetration. The test results show that in the 28 groups of composite active agent, Most formula can make the weld depth reach about 2 times without flux, and the better formula is group H6, which the increased penetration ratio can reach 2.67, and the weld surface forming is good; in the respect of weld penetration, compared to the conventional TIG welding, welding parameters have a significant impact on activity of welding, but the effect on weld width is relatively small; what is more, the penetration reached the maximum when the composite fluxes coating is 5.3 mg/cm2 or so.