Investigation of Electro-Plastic Effect on Advanced High Strength Steels and Its Application in Friction Stir Joining of Dissimilar Material

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

This grant provides funding for a comprehensive investigation of the electro-plastic effect on advanced high strength steels and its potential applications to the friction stir joining processes. In this research, microstructure analysis will be carried out to understand the underlying mechanism of electro-plastic effect. Basic stress strain model will be established with regard to strain rate and current parameters. An energy coefficient considering the ratio of the reduced deformation energy to the total electrical energy input will be introduced. In addition, an advanced hybrid friction stir joining process will be developed for the joining of dissimilar materials utilizing the above-mentioned electro-plastic effect. The materials to be joined include advanced high strength steels and aluminum alloys. Experimental results will be analyzed considering both process parameters and joint quality and a Finite Element Model will also be developed to predict the downward force during the hybrid friction stir joining process. If successful, the results from this research will lead to optimized designs of new joining processes for dissimilar materials. Dissimilar materials with high specific strength, such as aluminum alloys, magnesium alloys and advanced high strength steels, are being increasingly used in vehicle structures to reduce the weight of vehicles without sacrificing desired performance due to the growing challenge of improving fuel economy. Joining of these dissimilar materials presents a significant technical challenge. This research will greatly widen the applications of electro-plastic effects into various manufacturing processes, including traditional machining and forming etc. The proposed work will also contribute to the modeling and experimental tools available for characterizing electro-plastic effects and hybrid friction stir processes.