Effects of Zinc Insert and Al Content in Mg Alloy on the Bondability in Dissimilar Joints of Steel and Magnesium Alloys

In these days, global warming and energy issues are social problems to be solved for human being. Auto manufacturers are, therefore, forced to solve these issues as quickly as possible. One of resolution methods is to improve fuel consumptions. Processes for this include reducing car weight, lowering travel resistance, advancing drive-train efficiency, developing new source of power and so on. In particular, reducing weight of car bodies is one of the most efficient solutions . For this purpose, automobile industry has been trying to use aluminum alloys and magnesium alloys to attain lighter car bodies . To achieve light weight, safety and low cost, the multi-material structure using steels, aluminum alloys and magnesium alloys is considered to be efficient . To this end, effective dissimilar joining process of such light metals and steels is essential. However, in joining of such light weight alloys, surface oxide films prevent from gaining sufficient joining. In particular, it is very difficult to bond steels and magnesium alloys because Mg hardly react with Fe. Therefore, to establish a highly reliable metallurgical joining method of magnesium alloys and steels is important. In this study, we focus zinc insert, which can react with both Mg and Fe, and evaluated the effects of zinc insert and Al content in Mg alloys on the bondability in dissimilar steel/Mg alloy joints.