Metal pipe joining with aluminum alloy by ultrasonic insert casting

Insert casting of aluminum is widely used in industry. In order to realize better metallurgical bonding between metallic pipe and aluminum alloy castings, a new insert casting method with aided by high-power ultrasound has been developed. The bonding strength between the metal pipe and the cast aluminum alloy was evaluated by shear testing. EPMA analysis at the bonding interface was performed. The experimental results indicate that the application of ultrasonic vibration was effective during insert casting, particularly immediately after the primary α phase began to emerge in the cast aluminum melt. In the case of 6061 Al pipe/AC4C joint, the shear strength was approximately 60 times higher than without ultrasound vibration. This bonding reflects the break up of the oxide film on the aluminum pipe surface by the ultrasound cavitation effect. For the steel pipe/AC4C joint, the bonding shear strength had a several-fold enhancement. Ultrasound may promote a chemical reaction between steel and cast aluminum alloys, leading to excellent bonding.