An investigation of electrical-assisted solid-state welding/bonding process for thin metallic sheets: Experiments and modeling

Abstract

Efficient joining technique of thin metal sheets is required in the mass production of fuel cell bipolar plates, micro-reactor carriers and so on. Solid-state bonding (pressure welding) process is found to be a promising solution, because the process is efficient and large area welds can be achieved in one welding/bonding procedure. However, successful bonding cannot be achieved by conventional pressure welding process for some materials (e.g. stainless steel). In order to realize successful bonding and improve the bond performance, an electrical-assisted solid-state welding process was proposed in the present study. Experimental setup was developed to investigate the joining process of stainless steel and brass sheets. The effects of electric current as well as process conditions (e.g. welding pressure, sheet thickness and temperature) on the bond strength were studied experimentally. The results indicate that the maximum bond strength of stainless steel improves from 24.4 to 33.2 MPa with the increase of current density from 6.7 to 20 A/mm2. Furthermore, an analytical model to predict the shear load force was established. In the model, different deforming behaviors of the contaminant layer and the virgin metal were discussed. Good agreement between the analytical and the experimental results was observed. Based on the model, the improvement of the weld strength in the electrical-assisted solid-state welding process was characterized theoretically, which also proves the feasibility of the process.