Joining of 2024 Aluminum Alloy Stud to AZ80 Magnesium Alloy Extruded Plate by Advanced High-Speed Solid-State Method

Abstract

For its potential usefulness for weight reduction, an advanced high-speed solid-state joining method was tested for its applicability to the joining of 2024 aluminum alloy studs to AZ80 magnesium alloy extruded plates. In this method, a stud having a circular projection at its bottom is pressed against a plate surface, whereupon a discharge current applied to the upper part of the stud flows through a contact point between the projection and the plate to form a joint between them. Observations of the joint area reveal a projection structure sticking into the plate and bending toward the outside, in line with the predominant path of current flow. Refined grains of AZ80 magnesium alloy were observed in the vicinity of the joint interface. This reveals that local plastic deformation and heating induced dynamic recrystallization within the plate. Tensile fracture strength was not found to increase with increasing discharge voltage. To maximize that strength, it was instead found necessary to select an appropriate discharge voltage.