Effect of Al2O3 substituting SiO2 on the basic properties of high TiO2 mold slags
Aiming at the problem of TiO2 increase and slag denaturation caused by steel-slag reaction in traditional mold slags for the casting of high titanium steel.In this study,rotational viscosity measurement,hemisphere point measurement,FactSage thermodynamic calculation and in-situ crystallization observation are conducted.The effect of Al2O3 substituting SiO2 on the flow,melting and crystallization characteristics of the mold slags of high titanium steel after reaction was studied in order to regulate the properties of the TiO2-containing mold slags through the change of composition.Results show that when the TiO2 content in the slag is 12％,and the A12O3 content increa-ses from 0％to 12％,the viscosity of the slag increases from 0.14 Pa·s to 1.34 Pa·s,and the melting tempera-ture of the slag increases from 1 095 ℃ to 1 172 ℃.The activation energy of viscous flow increased from 128.4 kJ/mol to 389.1 kJ/mol.When A12O3 replaces SiO2 from 0％to 10％,the binary alkalinity of the slag also increases from 0.72 to 1.0.The initial crystallization phase of the slag calculated by thermodynamics is CaTiO3,followed by the precipitation phase is cuspidine.When A12O3 replaces SiO2 at 12％,the basicity rises to 1.08,and then the precipi-tated phase changes to NCA2.When the A12O3 content is 4％-12％,the crystalline phase in the air-cooled slag de-tected by XRD is CaTiO3.When Al2O3 in slag increases from 0％to 12％,the complete crystallization temperature increases from 728 ℃ to 1 214 ℃.Therefore,in the TiO2-containing mold slag discussed in this study,the replace-ment of SiO2 by Al2O3 will cause a significant increase in the viscosity,melting point and crystallization properties of the mold slag.In order to ensure the lubrication of the mold slag on the slab during the continuous casting,the con-tent of Al2O3 in the slag should be decreased when the traditional calcium-silicon mold slag is used to cast high tita-nium steel.The content of Al2O3 in the slag should be increased to enhance the control of the heat transfer of the slag.
high titanium steelmold slagAl2O3 substituting SiO2viscositycrystallization
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