Experimental Study on Micro-Friction Stir Welding of Dissimilar Butt Joints Between Al 1050 and Pure Copper

The present study investigates the feasibility of producing strong and defect-free joints between 1050 aluminum and pure copper sheets by micro-friction stir welding using traditional and new tools. Many variables affect the quality of these types of joints that the parameters of rotational speed, welding speed, and tool offset are considered the main variables. The Taguchi method and analysis of variance were used to design the experiments and evaluate the obtained results. By analyzing the results of the tensile test and signal-to-noise analysis, the average maximum ultimate tensile strength of the joints is reported to be 88 MPa, when using the parameters of rotational speed, welding speed, and offset of the tool with levels of 2400 rpm, 40 mm/min, and 0.25 mm. The analysis of variance also showed that the parameters of rotational speed and welding speed, respectively, had the most significant effect on the tensile strength of the joints. The maximum and minimum values obtained from the microhardness test were recorded for the weld nugget zone and the heat-affected zone of aluminum, respectively, which are equal to 192 HV and 21 HV. Also, by performing sanding operations, the roughness of the joints is significantly reduced. The x-ray diffraction test results on optimal samples showed the presence of intermetallic compounds CuAl2 and Cu9Al4 in the welding area. The tensile strength of the joints created is strongly dependent on the formation of these intermetallic compounds.