Friction stir lap welding of Al to Mg assisted by ultrasound and a Zn interlayer

Abstract

Abstract The friction stir lap welding (FSLW) joints of Al/Mg dissimilar alloys presented better formation and higher tensile shear strength when the Mg alloy was selected as the upper plate. Compared with Zn-added FSLW, the Zn-added FSLW assisted by ultrasound further enlarged the effective lap width, improved the mechanical interlocking and attained the finer disperse Mg-Zn intermetallic compounds in the stir zone. The maximum tensile shear strength of the joint assisted by ultrasound and a Zn interlayer reached 268 N/mm. This hybrid process with the ultrasound and the Zn interlayer provides a new method to obtain a high-quality Al/Mg dissimilar welding joint.