The joint properties of copper by friction stir welding

The objective of this work was to demonstrate the feasibility of friction stir welding (FSW) for joining of copper. Defect free weld were produced on 4 mm thick copper plate at travel speed of 61 mm/min and tool rotation speed of 1250 rpm using a general tool steel as the welding tool. The stir zone showed the very fine and equaxied grain structure compared to the base metal which had a elongated grain and its size is approximately 100 μm. The heat-affected zone (HAZ) which lies beside the stir zone had a near-equaxied and larger grain structure than that of the base metal due to annealing effect. Slight softening region was formed in the weld zone due to lower density of dislocation relative to the base metal. Transverse tensile strength of FSW copper joint reached about 87% of that of the base metal and showed slight higher value than that of the EBW copper joint.