Abstract: During continuous casting, the ZrO₂-C slag-line exhibits good thermal shock resistance and poor wettability with molten steel at high temperature. However, severe corrosion and scouring of the slag-line by the mold flux limit the service life of the submerged entry nozzle (SEN). In this paper, the method of applying an electric field to improve the corrosion resistance of slag-line was proposed, and the effects of the electric field on the slag-line decarburization and its corrosion resistance in mold fluxes with different basicities were systematically investigated. The results show that obvious decarburization occurred in the slag-line without the electric field. The positive electrode with the electric field enhanced the graphite activity, promoting reactions and dissolution. Conversely, the decarburization of the negative electrode slag-line was suppressed, and this phenomenon increased with the increase of voltage intensity. In low basicity mold flux, high SiO₄^4- ion concentration was the key to improving the corrosion resistance of slag-line. The applied electric field mainly improved the corrosion resistance by inhibiting decarburization and electrolyzing the Si enrichment layer at the interface. At 3 V, the corrosion rate of the slag-line was only 3.84 %, approximately 37.86 % lower than that of the reference sample. With increasing mold flux basicity and decreasing SiO₄^4- ion concentration, the electric field mainly improved corrosion resistance by inhibiting decarburization. Furthermore, the adhesion of mold flux to the slag-line surface was primarily related to the surrounding Ca²⁺ concentration. The high Ca²⁺ concentration promoted the formation of CaZrO₃, and then formed a shell. In actual production, the dynamically balanced composition of the mold flux prevented such adhesion. Therefore, this work provides a universally applicable strategy for enhancing the corrosion resistance of ZrO₂-C slag-line and offers profound insights into the corrosion resistance mechanism.

Key words: Mold flux, ZrO₂-C slag-line, Corrosion resistance, Continuous casting, Electric field