The Mechanism of the Impact of Purity on Resistivity is Reflected in the Steel Collector Bar Used in the Aluminum Electrolytic Cell

Reducing the resistivity of steel collector bars while maintaining mechanical strength is a critical challenge in enhancing the energy efficiency of aluminum electrolysis cells. This study aims to unravel the specific mechanism through which iron purity affects electrical resistivity. We systematically investigated three commercial steel grades—Q195 (99.23% Fe), SAE1006 (99.84% Fe), and a high‐purity iron HYT2 (99.96% Fe)—serving as models with varying purity. Their microstructure, mechanical properties, and resistivity were characterized using optical microscopy, scanning electron microscopy (SEM), EBSD, and XRD. We conducted a quantitative analysis to decouple the individual contributions of grain boundaries, dislocations, and most importantly, impurity atoms to the overall resistivity. ANSYS simulations were employed to project the impact of these findings on the electric field distribution within an operational electrolysis cell. The results demonstrated that resistivity decreases significantly with increasing iron purity. Our quantitative analysis conclusively identified that among all factors,scattering from non‐ferrous impurity atoms is the dominant mechanism governing resistivity, overshadowing the effects of grain size and dislocations. Implementing the high‐purity HYT2 collector bar can potentially reduce the cathode voltage drop by 23 mV. This work provides a strong technical rationale for employing high‐purity iron to achieve substantial energy savings in industrial aluminum production.