Development of Ultrahigh-Basicity Mold Fluxes for Peritectic Steel Continuous Casting

In the continuous casting of peritectic steels, mold fluxes play significant roles in providing defect-free surfaces of slabs. In this work, a traditional high-basicity mold flux was studied. Slag film samples were solidified from molten flux, with an improved water-cooled copper probe and using different probe immersion times. The film microstructures, interfacial roughness and porosity were studied. Based on the results, ultrahigh-basicity mold fluxes (CaO wt%/SiO₂ wt% = 1.5 ~ 1.8) were developed. A typical ultrahigh-basicity mold flux (CaO wt%/SiO₂ wt% = 1.74) was analyzed in the laboratory and applied in industrial processes. The laboratory experiments and industrial results indicate that the novel mold fluxes developed in this work have excellent performance in balancing heat transfer control by the solid film and lubrication by molten flux.