高合金鋼連続鋳造用モールドフラックスの高温熱物性に関する総説

抄録

Several recently developed highly alloyed steel grades have shown unsurpassed performance in terms of physical, chemical, and electromagnetic properties. However, broader commercialization of these steels has been hampered by limitations in mold flux performance. Newly developed steels containing considerable amounts of dissolved Al, Mn, and Ti actively react with typical CaO-SiO₂-based mold fluxes, which severely changes the composition and subsequently the thermophysical properties of the mold flux that determine the external and internal quality of the as-cast steels. These dynamic changes result in nonuniform heat transfer, lubrication issues, surface defects, and caster breakouts. This work critically assesses the current status of the high-temperature thermophysical properties of CaO-SiO₂-based and CaO-Al₂O₃-based mold fluxes intended for use in casting highly alloyed steel grades. Thermophysical properties, including viscosity, crystallization, thermal conductivity, and heat flux, have been evaluated. The effect of compositional variables including CaO/SiO₂, CaO/Al₂O₃, and Al₂O₃/SiO₂ mass ratios and the additions of CaF₂, B₂O₃, Li₂O, K₂O, Na₂O, TiO₂, and BaO on these high-temperature thermophysical properties are discussed.