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Presetting the taper on a joint will change the thermodynamic cycle of the interface in the direction of the rotating friction radius and affect the structure and joint mechanical properties. In this research, five types of conical Q235 low carbon steel rods at 5°, 10°, 15°, 20°, and 25° were paired with 1060 aluminum rods performed with continuous drive friction welding butt joint experiments. For these experiments, the temperatures of the interface center as well as 1/3R and 2/3R were collected during the welding process. After welding, the joints were subjected to tensile testing, fracture analysis, and microstructure analysis of the joint interface. The results showed that for the same process parameters, the increase in the tilt angle of the conical end face made the corona bonds of the friction interface of the joint move from the outside to the inside due to a decrease in the friction heat and an increase in the tangential stress, and the corona bonds became narrower. For certain technological conditions, a reasonable cone could improve the homogenization of the radial intermetallic compounds at the joint interface. The thickness of the intermetallic compound layer of the 15° tilt angle joints had the smallest gradient along the radius. The average thickness was about 0.85 μm and the average tensile strength reached a maximum of 77.5 MPa. This was 96 % of the base material of 1060 pure aluminum.

In the friction stir welding (FSW) of ultra-thin dissimilar metal sheets, different physical material properties, the reduction of plastic metal in the weld zone, and insufficient plastic metal flow lead to poor weld seam shapes and joint qualities. Therefore, it is necessary to study the flow behavior during the FSW of ultrathin sheets. In this study, micro friction stir welding (&mu, FSW) was conducted and analyzed for the butt welding of 0.6-mm-thick ultrathin brass (H62-H) and pure copper (T2-Y) sheets. By analyzing the electric signals of the temperature and force during the welding process, testing the mechanical properties, and analyzing the metallography of the joint, the influences of the process parameters on the metal flow behavior during &mu, FSW were studied. In the proper process conditions, the material preferentially migrated and concentric vortex flow occurred in the vicinity of the shoulder and tool pin action areas. The copper was pushed from the retreating side (RS) to the advancing side (AS) of the weld, allowing it to flow more fully. A mixture of both materials formed at the bottom of the weld nugget, and less migration occurred in the heat-affected zone of the AS at this time. The highest tensile strength can reach 194 MPa, accounting for 82.6% of the copper. The presence of brittle phases Cu5Zn8, AgZn3 and AgZn caused the hardness to fluctuate slightly.