Electrically assisted pressure joining of thin bi-layer aluminum-clad aluminum sheets

Abstract

The electrically assisted pressure joining (EAPJ) of thin bi-layer aluminum-clad aluminum (Al-clad Al) thin (1.5 mm) sheets is experimentally investigated to overcome the challenge from conventional fusion joining or brazing for a successful application of the Al-clad Al sheets in the battery containers of electric vehicles. With a constant pre-load (6 kN), a compressive displacement is applied to the specimen assembly in lap configuration to induce plastic deformation of the joining area while a pulsed electric current with varying current density is simultaneously applied through the joining area. Macroscopic observation reveals that the joining is successfully carried out in the solid state at a temperature significantly lower than the melting temperatures of the selected alloys. The results of microscopic analysis indicate the presence of deformed, elongated grains and Si particles distribution from the clad layer to the core during joining. After the EAPJ, while the AA 3003 core shows increased microhardness, the AA4343 clad layer shows slightly decreased microhardness, compared to the as-received material. The enhancement (the core) and reduction (the clad layer) of the microhardness can be linked to the changes in grain size, distribution of Si particles, and the formation of secondary phase particles. In the lap-shear tensile test, the EAPJed specimen shows the base metal fracture near the joining area, while the fracture surface indicates the ductile fracture. The results of the present study suggest that the concept of EAPJ is applicable to the newly developed bi-layer Al-clad Al sheets for electric vehicle components.