Friction Stir Welding of Dissimilar Metal Sheets

This study aimed to experimentally explore the thermal history of a workpiece undergoing friction stir welding involving butt joining with dissimilar metal sheets. In the FSW experiments, K-type thermocouples were used to record the temperature history at different locations in a workpiece. This data, combined with the preheating temperature, tool rotation speeds and tool moving speeds allowed parameters for a successful weld to be determined. The Vickers hardness tests were conducted on the welds to evaluate the hardness distributions in the welded product. Tensile tests were also carried out, and the tensile strength of the welded product was compared to that of the base metal. The FSW experiments of different species of A5052-A6061, C1100-C1100, and A6061-C1100 were conducted. The welding temperature for a successful FSW process of A5052-A6061 was found to be about 370 degrees C, whereas that for copper-copper sheets was about 530 degrees C. For FSW of A6061-C1100, two kinds of tool shoulder diameters were used. From the welding results, it was known that using a larger tool diameter of 15 mm could increase the welding temperature and improve the surface of the welds. These experimental results and process control of thermal histories can offer useful knowledge for a friction stir welding based process of aluminum and copper butt joining.