Abstract
Friction stir spot welding (FSSW) has already been used in many companies for joining light materials such as aluminum and magnesium alloys, and in recent years, this process is coming to use for dissimilar joints. It is important to understand the material flow during dissimilar FSSW to obtain a sound joint. In this study, the material flow and temperature history during dissimilar FSSW on magnesium alloys is investigated by experimental approaches. Results of the investigation indicate that the combination of the upper and lower sheet materials affects largely on the material flow and joint soundness. Furthermore, the selection of a tracer material to observe the material flow was discussed. It becomes also clear that the appropriate tracer material must be selected for the adequate investigation of the material flow during FSSW.
