Effect of ultrasonic on friction stir welding formation of aluminum/magnesium dissimilar alloys

Abstract

The friction stir butt joint process experiment of 6061 aluminum alloy/AZ31B magnesium alloy plate with thickness of 4 mm was carried out. The material flow in transverse cross-section and horizontal-section, the thickness of the intermetallic compound layers, the mechanical interlocking, and the tensile properties of conventional friction stir welding (FSW) and ultrasonic vibration enhanced friction stir welding (UVeFSW) were compared and analyzed. The action mechanism of ultrasonic vibration was explored. The results show that ultrasonic vibration can promote material flow and heat transfer in different parts of the joint, thereby reduce or even eliminate weld defects. When ultrasonic vibration is applied, the intermetallic compound layer at the aluminum/magnesium interface is thinned, and the mechanical interlocking on the interface is enhanced, so the tensile strength of the UVeFSW joints is improved compared to the FSW joint under the same process parameters. The maximum tensile strength of the UVeFSW joints reaches 174.20 MPa.

Keywords

• friction stir welding
• ultrasonic vibration
• material flow
• intermetallic compound
• mechanical interlocking
• mechanical property