Plasticity and size effects of micro-forming sheet processed by electropulsing

Abstract

ABSTRACT Commercial sheets need effective pretreatment to eliminate work hardening and anisotropy, and improve their forming properties to meet the requirement of micro-forming process. Compared with the traditional heat treatment, the electropulsing treatment (EPT) process has some advantages of performance improvement and consumes less energy and is environmentally friendly. It is a potential pretreatment method or process for sheets of micro-forming. In this paper, the effect of EPT on copper sheets with varying thicknesses and different grain sizes is studied. Electropulsing can significantly improve the plasticity of cold-rolled sheet, and plasticity improvement effect was better than that of heat treatment. The mechanical properties of copper sheets with different thicknesses which undergo electropulsing show the same size effect as that of samples without electric pulse. After EPT of copper sheets with different grain sizes, the flow stress difference decreased, which weakened Hall-Petch effect. As the thickness of copper sheets decreased, the threshold of current density for plasticizing effect increased. Based on the analysis of the dislocation motion induced by electropulsing, the mechanism of electropulsing to improve the plasticity of copper sheet was presented, which provides a reference for future research on the pretreatment process for micro-forming materials.