Study of the mechanical properties and microstructures of conical joints for aluminum/steel continuous drive friction welding

Abstract

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.