## 5 Example Verification of Mg Strip Electric Rolling  
Based on the above conclusions, it is demonstrated that the symmetric connection and copper-embedded steel roller can significantly improve the electric field uniformity of Mg strip, and indirectly modify the temperature distribution and microstructure of Mg alloy in the EPR. In order to verify the EPR effect of Mg alloy strip under the condition of symmetrical electrode connection, the anode of the power supply was connected on both sides of the work roll. The Mg alloy billet was cut into sheets with dimensions of 500 mm \(\times\) 40 mm \(\times\) 1.0 mm. The sheets were rolled to 0.6 mm thickness though three passes without any off-line intermediate heat treatment in the process of the EPR. Figure 8 shows that the rolled Mg strip produces a large number of twins and shear bands. Then, a single pass electroplastic rolling with an 18% reduction rate was performed. The effective current density was 28.5 A/mm\({}^{2}\), and the rolling speed was 25 mm/s.  
Figure 9 shows that the Mg alloy strip passes through the guide rolls into the deformation region in 6.2 s, and was subjected to Joule heat in the transition region to reach the target roll temperature. The transverse temperature distribution at the inlet measured by the thermal imager was relatively uniform. It can be seen that the temperature rise of the symmetric electric field after electrode attachment was more uniform under Joule heating, and there was no edge crack due to edge temperature drop. The optical micrographs show that the deformed twin and the shear band completely disappear before the mill inlet, and large area nucleation and recrystallization occurring at the edge and middle and fine recrystallized grains form in the shear band. Additionally, the grain sizes in the middle of the strip and at the edges of the Mg alloy are essentially the same. Therefore, the optimized electric field can significantly improve the uniformity of the rolling temperature and the uniformity of the microstructure properties at the inlet of the rolling mill, thereby improving the surface quality and mechanical properties of the rolled Mg alloy.  
A large number of studies on electrical pulse-assisted forming show that the pure electroplastic effect mainly manifests in two aspects: promoting recrystallization; and reducing flow stress. On the one hand, the presence of pure electroplastic effects could reduce the activation energy and accelerate the nucleation and recrystallization of the Mg alloy under the combined action of pure electroplastic and Joule thermal effects [19; 20]. On the other hand, the purely electroplastic effect that could reduce the flow stress and even greatly enhance the plastic deformability of the material without changing the temperature [17; 21]. It can be seen that the electric field of electroplastic rolling not only directly affects the flow stress and the microstructure evolution of the strip, but also indirectly regulates the rolling deformation by changing the temperature distribution. Symmetric electrode connections are characterized by low load and uniform electric field, with peak current densities on both sides of the strip. Strong currents can improve the rolling ductility of the material to a  
Figure 8: The initial microstructure of Mg strip in the EPR.  
certain extent, thus reducing the occurrence of edge cracks [22]. The non-thermal effects and a uniform transverse temperature profile may be responsible for the improved surface quality of the electroplastic rolling strips. The improvement of the symmetrical electrode connections and the copper rollers can not only improve the uniformity of the electric field, but also adjust the transverse temperature distribution and microstructure homogeneity of the electrically rolled Mg inlet by using the purely electroplastic and thermal effect.