Investigation on Dissolution Behavior of Non-metallic Inclusions in Tundish Fluxes for Bearing Steel Continous Casting

With the development of steelmaking technology, tundish has become an important device that can clean steel and remove non-metallic inclusions. Tundish flux plays a more and more important role in tundish metallurgy, furthermore different types of steel and metallurgy technology of tundish must be cooperated with the suitable tundish flux. The tundish metallurgy properties of magnesia and calcium fluxes for bearing steel production were investigated and compared by high temperature simulation experiment and industrial experiment, respectively. Results show that the melting temperature of magnesia tundish flux is higher than that of calcium tundish flux. The calcium flux has the better kinetic condition of dissolution non-metallic inclusions than the magnesia flux. Main crystal phases of magnesia tundish flux change from 12CaO·7Al2O3, 2CaO·SiO2 and MgO to 12CaO·7Al2O3, MgO, 2CaO·SiO2, CaO·Al2O3·3SiO2 and 3CaO·MgO·2SiO2 after absorbing Al2O3 inclusions. The slab samples of bearing steel ware analyzed by the big sample electrolysis method. Results show that the content and size of Al2O3 system inclusions in slab samples using calcium tundish flux are lower than using the magnesia tundish flux. Therefore, the calcium flux should be used to tundish metallurgy in bearing steel production.