Effect of friction stir spot weld parameters on Cu/CuZn30 bimetal joints

In this study, the effects of tool rotation speed, tool dwell time in maximum vertical load, and position of sheets to be welded in friction stir spot welding of copper/brass bimetal on microstructure and mechanical properties were investigated. Tensile-shear test was employed to determine the influence of the parameters. Microstructural examinations by optical and scanning electron microscopes, microhardness, and temperature measurements were also performed on the joint zones. Test results show that the weld parameters used have an important role on the tensile-shear failure load and failure mode. The tensile-shear failure load increased with increasing the tool rotation speed and dwell time and reached to 5.1 kN. The weld zone consisted of the heat-affected zones and stir zone in addition to the parent metals. The stir zone displayed the higher microhardness values than the other zones. The highest temperature of 545 °C was measured at the tool rotation speed of 1500 rpm during the experiments.