Study of a New Mold Flux for Heat‐Resistant Steel Containing Cerium Continuous Casting

Abstract

New mold fluxes with CaO–Al2O3–Li2O–CeO2 system are proposed for heat‐resistant steel continuous casting. The fundamental properties are investigated systematically. It is found that the appropriate content of CeO2 is determined to be ≈10 wt%, the melting temperature did not change much with increasing CeO2 content, which indicates that the mold fluxes could show steady smelting properties after continuously absorbing inclusions containing cerium in the continuous casting process. After adding CeO2, the precipitation of CaO in the crystallization process is restrained, and the crystalline phases are shifted from CaO/LiAlO2 to CaCeAlO4/LiAlO2. It is further evidenced that the precipitation of CaCeAlO4 and LiAlO2 can be restrained by CeO2. CeO2 shows significantly positive influence in decreasing the viscosity. Above the breaking temperature, the decrease of viscosity is attributed by the cutting off the chain structure of the molten slag from CeO2. Below the breaking temperature, it is caused by the effect of CeO2 on restraining the crystallization process. The optimal content of Li2O is 14 wt%, with a content of less than 14 wt%, Li2O can reduce the melting temperature and viscosities obviously, but the fluxing action of Li2O becomes ineffective when the content of Li2O exceeds 14 wt%. The results have great theoretical significance for developing mold fluxes for heat‐resistant steel.