Mechanism Of Influence Of Electroplastic Effect On Metal's Flow Stress And Experimental Study

Electroplastic effect can be employed to increase metal forming limit,reduce deformation resistance and improve surface quality of product.Electroplastic forming can also be used as a new technology to eliminate localstress and improve product performance, since internal residual stress decreasessignificantly when electroplastic effect existing. At present, the mechanism ofelectroplastic effect is so clear by far, and theory analysis of electroplasticforming process has become a bottleneck of the application of electroplasticforming technology. It is, therefore, of great importance to perform research onthe mechanism of electroplastic effect and computation methods.In this work, the historical review and updated progress on the research ofelectroplastic effect is presented. By investigating the influence of single pulsecurrent on material flow stress, formulations of flow stress calculation underuniaxial tension with pulse current applied are deduced thereafter, and it showsthat the flow stress reduction results from the effect of current on strain rate.These theories are expected to provide a foundation for investigating theinfluence of current on metal flow stress.A pulse generator was developed for the electroplastic effect test, in which555 time base integrated circuit and Darlington transistor are used to generatepulse current, and control the circuit conduction and cut-off. The generator iscapable of meeting the requirements of pulse current density, frequency andpulse width. At last, to validate the calculated results, experimental research ontensile tests of copper wire was carried out, and the influences of current density,temperature, strain and strain rate on material flow stress during forming processcompanied with electroplastic effect have been determined quantitatively.