Experimental Investigation of Tensile Properties of SS316L and Fabrication of Micro/Mesochannel Features by Electrical-Assisted Embossing Process

Abstract

During the electrical-assisted forming process, a significant decrease in the flow stress of the metal is beneficial to reduce the required force for the deformation with high-density electrical current introduced through the materials. It is an alternative manufacturing process of traditional hot forming to improve the formability without the undesirable effects caused by elevated temperature, such as surface oxidation. In this study, tension tests and electrical-assisted embossing process (EAEP) experiments were performed to study the electroplastic (EP) effect with high-density pulse current applied to the specimen and demonstrate the advantage of EAEP. In the first section of this study, specimens with various grain sizes were well prepared and an experimental setup was established to study the flow stress of SS316L sheet in the electroplastic tensile test. Extra cooling system was developed and the temperature increase caused by resistive heating was controlled. Thermal influence caused by resistive heating was thereby reduced. The impacts of the pulse current parameters on the flow stress were investigated. It was observed that the flow stress of the SS316L specimens was significantly reduced by the electroplastic effect. In the second section, the EAEP was proposed to fabricate microchannel feature on metal workpiece. Experiments were conducted to demonstrate the feasibility and advantage of the novel process. The protrusion feature height and microstructure of the grain deformation were measured to investigate the effect of the process parameters, such as the current density, the die geometric dimension, and the grain size of the specimen. Larger feature height was measured owing to the higher density current, which meant the electroplastic effects were helpful in EAEP.