Dissimilar Metal Joining of Steel to Aluminum using the Arc Heat Source

Car manufactures have been asked to avoid the unnecessary waste of energy and reduce pollution. Replacing steel with lightweight materials on car bodies is considered as one method to reduce the vehicle weight to achieve these requirements. Therefore, in this study, we selected a modified metal inert gas welding-brazing process to join aluminum to zinc coated steel on the lap geometry. The main purpose of this research was to reveal the relationship between weldability and various process parameters such as Zn coated thickness, kind of coated treatment type, filler wire type and welding condition. Metallurgical observations and mechanical testes were carried out to evaluate the weld quality. Based on these results, we could find that the weldability of dissimilar materials were depend on sufficient and regular wetting by heat input and gap condition. The tensile-shear test results, all the fracture occurred in the HAZ of aluminum and the strength was up to 70% of base metal of aluminum. However zinc coated thickness in the range of 10(mu m) to 30(mu m) was no related with welded strength. Also we could find that silicon content of filler wire is very important to minimize the thickness of intermetallic compound layer. Silicon might be disturbed to the growth intermetallic compounds.