Study on a Novel Electrical-Assisted Pressure Welding Process of Thin Metallic Foils

Abstract

Joining of very thin metallic foils is required in vast applications such as fuel cell plates, micro reactor carriers, heat exchanger etc. Pressure welding is found to be an efficient method. However, some metals (e.g., stainless steel) are difficult to achieve successful solid state bond at room temperature. In present study, a novel electric assisted pressure welding (EAPW) process was proposed. In the EAPW process, electric current was introduced to the metal sheets under pressure welding in the purpose of reducing welding difficulty. An EAPW experimental setup was developed to study the joining process of Stainless Steel (SS) 316 sheets. The effects of electric current as well as process conditions on the final bond strength were experimentally studied. It was found that SS316 sheets could not be bonded without current at room temperature. However, they were successfully joined with electric current introduced. The co-effects of temperature and electric current were also investigated experimentally. It was found that elevated temperature caused by Joule heat is not the only reason for the improvement of the welding performance. The so-called electro-plastic effect also makes a contribution in EAPW process. Finite element method (FEM) was also employed to analyze the process and the welding behavior was discussed.