Aluminum Alloy A-tig Welding Of Active Agent Developed Its Melting Deep Increase Mechanism

Aluminium alloys have been intensively applied in mordern industry, because of light weight, high intensity and corrosion proof. TIG welding used as the common welding process for aluminium alloys has many advantages, including high welding quality and all position welding etc. Normally, it is used to weld thin plate owing to poor penetration and low deposition coefficient in one weld. In this study, A-TIG (Activating flux TIG) welding -- one high efficient welding process is introduced in the welding for aluminium alloys. Many foundational experimental studies are made to improve penetration and productivity.In this paper, an A-TIG welding flux has been developed with the " uniform experimental design method", improving the weld penetration over 3 times, unchanging weld chemical composition and fining weld micro-structure compared with weld of the conventional TIG welding.Some experiments, including weld deviation experiment, A-TIG welding experiment with DCSP mode and FBTIG welding experiment, are made to study the mechanism of activating flux improving penetration. It is found, current channel resistance has greater effect on the penetration of A-TIG welding for aluminium alloys. Especially in A-TIG welding with DCSP, the change of heat input due to the change of current channel resistance is the main effect. In FBTIG welding for aluminium alloys, arc is restricted to dramatically increase penetration due to high melting and boiling temperature and high electrical resistivity of the flux only when the flux gap is much smaller than the weld width of conventional TIG welding and A-TIG welding. The mechanism of the A-TIG flux developed by ourselves increasing penetration probably is: the flux is melted and decomposed under the influence of arc. The metal elements decomposed are fused with the elements coming from the base metal and distribute on the surface of welding pool, which results in many separate micro-sections. In these separate micro-sections, arc spots is restricted. The current density in these restricted arcspots and the Lorentz force in welding pool are increased, which improves penetration dramatically.Because no people in China studies A-TIG welding for aluminium, and only French scholars have started this study abroad, this study work has a directional significance in the application of A-TIG welding for aluminium alloys and has an important theoretic significance in the study of mechanism of A-TIG flux improving penetration.