Microstructure and mechanical properties of friction stir butt welded dissimilar pure copper/brass alloy plates

The present study is focused on the effect of tool rotation speed on the microstructure and mechanical properties of butt welded dissimilar pure copper/brass alloy plates by friction stir welding. The joint performances were evaluated by microhardness measurements, tensile and bend tests. The results show that the grain size and the onion ring formation in the weld nugget zone and the mechanical properties of the joints were affected by tool rotation speed. It was found that the tensile strength of the joints was lower than that of the copper and brass base metals, while the bend strength was higher than that of the copper base metal and lower than the brass base metal. The highest mechanical properties were obtained from a tool rotation speed of 800 rpm at a travel speed of 22 mm min(-1). The average microhardness values in the weld nugget zone increased with decreasing the tool rotation speed.