## 4 Result
### Electro-Thermal Field Uniformity Analysis  
In order to better evaluate the uniformity distribution characteristics of the electric field, the \(J_{e}/J_{ave}\) of the sample after one second was calculated according to Equation (1). Figure 3 shows the measured values of the electric field, with a peak \(J_{e}/J_{ave}\) less than 1.4 for the cylindrical electrode electrical pulse tensile test. The \(J_{e}/J_{ave}\) peak is lower and the electric field is more uniform after applying the packet Angle. In order to eliminate the  
\begin{table}
\begin{tabular}{c c c c c} \hline  & **Density** & **Electrical Resistivity** & **Specific Heat Capacity** & **Thermal Conductivity** \\  & \(\rho\)/(kg\(\cdot\)m\({}^{-3}\)) & \(R\)/(n\(\Omega\cdot\)m) & \(c\)/(l\(\cdot\)kg\({}^{-1}\cdot^{\circ}\)C\({}^{-1}\)) & \(k\)/(W\(\cdot\)m\({}^{-1}\cdot^{\circ}\)C\({}^{-1}\)) \\ \hline AZ31 & 1770 & Temperature-dependent [18] & Temperature-dependent [18] & Temperature-dependent [18] \\ Copper & 8960 & \(1.72\times 10^{-8}\) & 385 & 400 \\
9 Cr2 Mo & 7850 & \(2.48\times 10^{-7}\) & 475 & 44.5 \\ \hline \end{tabular}
\end{table}
Table 1: Material coefficient.  
Figure 3: The \(J_{e}/J_{ave}\) measurement value surface fitting: (**a**) 9 Cr2 Mo\(-\)asymmetry\(-\)5.0A/mm\({}^{2}\); and (**b**) 9 Cr2 Mo\(-\)symmetry\(-\)5.0A/mm\({}^{2}\).  
the electric field in the wide Mg alloy strip more uniform, which is beneficial for improving the uniformity of the transverse temperature distribution and microstructure.  
The results of electric tensile experiment and finite element simulation both confirm that the copper-embedded roll can significantly improve electric field homogeneity. However, the calculated coefficient of variation for the experimental values has a larger gap than the simulated values, which proves that the actual uniform electric field effect is more pronounced for the copper-embedded guide rolls, as shown in Figures 4 and 6. Contact resistance was unavoidable during the assembly of the copper-embedded rollers and the installation of the device. A small change in the resistance affects the characteristics of the electric field. The contact resistance between the copper core and the steel roll reduces the radial current conduction capability, and equivalently enhances the axial current conduction capability, resulting in a more homogeneous roll electric field. The experimental results show that the transverse distributions of the electric field and temperature are strongly  
Figure 5: The \(J_{e}/J_{\text{ave}}\) distribution of tensile device with wrap angle: (**a**) 9 Cr2 Mo-asymmetry-5.0 A/mm\({}^{2}\); and (**b**) 9 Cr2 Mo-symmetry-5.0 A/mm\({}^{2}\).  
Figure 6: Variable coefficient of the \(J_{e}/J_{\text{ave}}\) simulation value in the electrical tensile with wrap angle.  
Figure 7: The current density \(J_{e}\) of cylindrical axis electrode: (**a**) 9 Cr2 Mo; and (**b**) Copper + 9 Cr2 Mo.  
affected by the electrode connection pattern. Therefore, the feasibility of the symmetric electrode connection method was first verified, and the effect of the electric field on the transient rolling temperature and microstructure was analyzed and optimized.