Electrically assisted solid state lap joining of dissimilar steel S45C and aluminum 6061-T6 alloy

Abstract

Lap joining of dissimilar steel S45C and aluminum 6061-T6 alloy sheets in the solid state is conducted by means of electrically assisted pressure joining (EAPJ). During joining, electric current is applied to a specimen assembly under continuously compressive plastic deformation. Additional holding time at the elevated temperature is also applied by periodically applying electric current after the completion of compressive deformation to enhance the diffusion between the steel and aluminum alloy sheets. Microstructural analysis confirms the solid-state joining and shows that the microstructure of the joint strongly depends on the process parameters. Quasi-static lap shear tensile testing shows that joint strength increases with increasing electric current density and with increasing holding time at the elevated temperature. Fracture surface morphology suggests that brittle fracture occurs at the interface between the steel and aluminum alloy, with some amount of intermetallic compound sticking to the steel side. The present study confirms that the EAPJ concept is applicable to the joining of steel and aluminum alloy in solid state.