Microstructure and properties of joint of Mg/Al resistance element welding with a magnesium element

Abstract Resistance element welding was performed using A6061 aluminum alloy as the upper plate and AZ31B magnesium alloy as the lower plate. Rivets with leg diameters of 4 mm, 6 mm, 8 mm, and 10 mm were utilized as the element. The impact of welding current and welding time on the tensile shear load of the joint was investigated, in addition to conducting an analysis of the microstructure of joint. The tensile shear load of the joint reached the maximum value of approximately 5.19 kN when a rivet with a leg diameter of 10 mm was used under the conditions of a welding current of 25 kA and a welding time of 160 ms. The results reveal that a reaction layer formed at the interface between the aluminum alloy rivet leg and the magnesium alloy upper plate and it consistently comprised a single row of Al12Mg17 grains elongated parallel to the interface plan irrespective of whether the magnesium alloy was in a solid or liquid state during welding.