Effects of activating flux on aluminum alloy to steel butt-joint using a MIG weld-brazing process

抄録

A novel metal inert gas (MIG) weld-brazing was employed to produce the dissimilar materials butt-joint welds that specimens consisted of 6061 aluminum (Al) alloy and galvanized steel sheet. In this process, the fluxes such as CaF₂, TiO₂, SiO₂ and ZnO powder were coated on the surface of steel respectively to investigate the effect of activating fluxes on the performance of specimens. The experimental results revealed that CaF₂ flux powder was applied as a suitable flux which spreadability of filler material on steel surface become better. In order to obtain better appearances of specimen surface, the coating thickness of flux powder should be accurately control at 0.1 mm. When SiO₂ flux powder was coated on surface of specimen, the amount and the size of porosity decrease simultaneously in the fusion zone (FZ) of weld bead. It led to improve the tensile strength of Al/steel butt-joint specimens. The surface of specimens coating with CaF₂, TiO₂ or SiO₂ flux powder, the thicknesses of intermetallic compound (IMC) layer were less than 10 μm. The specimens produced by coating with ZnO flux may increase the temperature of FZ, the average thickness of IMC layer was 14.62 μm and the IMC layer presents a saw tooth shape.