Effects of the MIG weld-brazing parameter on the lap-joint performance of aluminum alloy to galvanized steel sheet

The weld-brazing lap-joint of automotive galvanized steel to 6061 aluminum alloy sheet was achieved employing a metal inert gas (MIG) welding process. In this novel weld-brazing process, the welding feed, welding voltage and travel speed of welding torch were selected to investigate the lap-joint performance of specimens. The experimental results demonstrated that the specimens produced by welding feed at 115 mm/sec, welding voltage at 22V and travel speed of MIG welding torch at 600 mm/min were provided with better welding performance such as weld bead geometry, microstructure and tensile strength. The average tensile strength of lap-joint welds of automotive galvanized steel to 6061 aluminum alloy sheet that produced with above MIG welding parameters is 130.53MPa. The amount of porosity and grain size of welds that produced with optimal parameters is smaller than others. In addition, it can be found that the intermetallic compounds (IMCs) layer between the galvanized steel sheet and weld bead using the scanning electron microscopy (SEM). The thickness of IMCs layer was the thinnest and its thickness from 3.51μm to 3.90μm.