Viscosity, Crystallization, and Heat Transfer of Mold Slags for Casting of Cold‐Work Die Steel Under Varying Basicity and MnO/Na 2 O Ratio

In the current study, the effect of varying basicity and MnO/Na 2 O ratios on the viscosity, crystallization behavior, and heat transfer of mold slags for the continuous casting of Cr12MoV cold‐work die steel is investigated to obtain the slag with excellent lubrication and low‐heat transfer. With the increase of basicity from 0.95 to 1.15, the melting temperature, break temperature, initial crystallization temperature, and the crystallization ratio increase from 996 to 1017 °C, from 1003 to 1044 °C, from 895 to 977 °C, and from 0% to 93.4%, respectively, while the steady‐state heat flux decreases from 1.20 to 0.79 MW m −2 . The main crystallization phases exist as Ca 3 MgSi 2 O 8 and Ca 4 Si 2 F 2 O 7 . With the increase of MnO/Na 2 O ratio from 0 to 0.5, melting temperature, and initial crystallization temperature increase from 896 to 976 °C, and from 1003 to 1044 °C, respectively, while break temperature, the crystallization ratio, and the steady‐state heat flux decrease from 986 to 952 °C, from 90.5% to 0%, and from 1.13 to 0.98 MW m −2 , respectively. Hence, the increase in basicity and MnO/Na 2 O ratios weakens the heat transfer of mold slag to avoid the surface crack of cold‐work die steel slab.