Study Of Activating Flux Zoned TIG Welding For Aluminum Alloy

During the activating welding of aluminum alloy, the weld penetration and weld appearance could not match well, in this paper, on base of many experiments and theoretical analysis, a new idea of flux zoned activating TIG welding (FZ-TIG) was bring forward during the welding of aluminum alloy which will solve the problem. Before the TIG welding, in the center area of the aluminum alloy flat, the low resistively, low melting point and low boiling point activating flux was coated, then the high resistively, high melting point and boiling point activating flux SiO₂ was coated alongside the former.In this paper, a FZ-TIG activating welding flux-FZ108 which was coated in the center area of the aluminum alloy flat has been developed with the "uniform experimental design method". In the FZ-TIG welding, this activating flux FZ108 and SiO₂ will not only improve the weld penetration to 3.3 times, but also get the perfect weld surface appearance. Some experiments, including alter the welding current, welding speed, change the FZ108 flux coating wideness, kinds of solvents and the discharge variation of argon gas are made to study the effect of weld penetration when these processing parameters have changed. The FZ-TIG could thin grains of metallurgical structure. The testing of weld bead mechanical showed that the FZ-TIG can improve the hardness of weld bead, but have little influence on weld intensity. Through the XRD test of welding slag, it shows that the FZ108 Flux can take action with the parent metal Al and surface oxidation membrane Al₂O₃ at the high temperature of arc, and the metal oxide and the metal of simple substance have produced. The effects of improving the weld penetration with DCSP FZ-TIG have also been studied.In this paper, changes of the arc length experiment are made to study the effects of activating fluxes on the arc polarity region voltage and the arc pole region voltage grades. The weld deviation experiment is made to analyses the influence of the activating fluxes to the current channel resistance. The effect of activating flux on arc and welding pool in the TIG welding with helium shielding gas experiment have also been studied. The results show that, the mechanism of activating flux improving the FZ-TIG welding penetration mainly is the arc constriction: on the one hand, the FZ108 particles can adsorbed the electron at the low-temperature region, which decrease the electronic number, narrow the current channel, shrink the arc column after evaporate into the arc; on the other hand, during the FZ-TIG welding, the activating flux SiO₂which coated alongside the FZ108 activating flux can become the insulating layer because it have high resistively, high melting point and boiling point, which can make the arc bottom constriction in the area which have the low resistively, low melting point and low boiling point activating flux. Because the two affects upon, the Lorentz force of the arc and the welding pool are improved due to the arc constriction, and the welding penetration improved greatly.Because there are few expert who study the activating flux welding for Aluminum alloy, so this study work has an important theoretic significance in the study of mechanism of activating flux improving the welding penetration, also has an important significance in the application of activating welding for Aluminum alloys.