Friction-Assisted Dissimilar Solid State Lap Joining of Aluminum and Copper Pipes

Abstract

The friction-assisted solid state lap joining process of dissimilar metal pipes is proposed by joining copper (Cu) and aluminum (Al) pipes. The joining process is designed to have two successive stages. In the first stage, the Cu pipe rotating with a mandrel rotates against the inner surface of the Al pipe. In the first stage, the relative rotation between the Cu and Al pipes breaks the oxide layers on the contacting surfaces and increases the temperature at the interface. In the second stage, as the area of the contact surface between the Cu and Al pipes increases due to the linear motion of the mandrel; as the mandrel begins to rotate alone against the Cu pipe, which now becomes stationary to induce diffusion bonding between the Cu and Al pipes. The results of microstructural analysis and mechanical testing show that solid state lap joining between the Cu and Al pipes for a light-weight heat exchanging component is successfully achieved. The microstructure evolution suggests that grain refinement by recrystallization occurs in the joining region for both the Cu and Al sides.