Study On Effect Of Transition Metal Oxides On Heat Transfer Through Mold Fluxes Film In Continuous Casting

In continuous casting of steel, mould fluxes infiltrates between strand and mould , forms a film consisting of solid layer, predominantly glassy, (typically 1-2mm thick) and a liquid layer(ca. 0.1 mm thick) next to the strand. Sometimes, the solid glassy layer crystallizes partially. The heat transfer from the shell to the mould is controlled by the properties of the solid flux film and the lubrication supplied by the flux film is determined by the thickness of the liquid layer. To minimize surface defects such as longitudinal cracking, it is necessary to control the heat transfer between the strand and the mould, especially for medium-carbon (MC) peritectic steel grades. The heat transfer process between the shell and the mould is very complex and heat can be transported by two mechanisms, lattice (phonon) conduction and radiation conduction.The mould fluxes samples added with transition metal oxides were designed based on the composition of commercial mould fluxes, and the relation between radiation conductivity and the content of transition metal oxides was examined by measuring the transmittance of The mould fluxes during infrared band and modeling radiation heat transfer between shell and mould to calculate the intensity of radiation heat transfer. Besides, the melting temperature, viscosity, temperature– viscosity curve and the mine phase of the fluxes was also determined. The result indicates:①additions of MnO and FeO were found to results in remarkable decrease of the radiation conductivity of fluxes. It is proved that MnO and FeO have a negative effect on the radiation heat transfer though the fluxes. Among the fluxes sample, the decreasing amplitude of F1-2, F3-1, M3-1, M1-3 is most obvious. The value q12 of M1-3 fall to 36% compared with based sample.②fluxes's crystallization leads to the deceasing of radiation conductivity, and the value q12 of crystallined samples tend to decrease with the increasing of MnO or FeO content.③The melting temperature, viscosity, break-temperature all decrease with the increasing of MnO. There is only a few changes with the increasing of FeO, for the content of FeO is only 1~3%. Additions of ZnO, NiO, TiO2 have a negative effect on viscosity and break-temperature, but a little positive effect on melting temperature.