Effect of basicity on flow,crystallization and structure of high TiO2-containing mold slags
In order to solve the problem for the increase of TiO2 content and the variation of slag property caused by steel-slag reaction when traditional mold slag was used to cast high-titanium steel,the effect of basicity on the flow,crystallization and structure characteristics of mold slag for high-titanium steel was studied by means of rotational viscometer,hemispherical point method,thermodynamic calculation by FactSage software,Raman spectroscopy and in-situ observation,so as to regulate the performance of TiO2-containing mold slag through the adjustment of slag composition.Results show that when the basicity of mold slag(with TiO2 mass fraction of 8％)increases from 0.6 to 1.2,the viscosity at 1 300 ℃ has the tendency to decrease from 0.33 Pa·s to 0.21 Pa·s,the melting tempera-ture of mold slag increases from 1 111 ℃ to 1 161 ℃,which is related to the slag structure and the precipitation of crystallization phases.With the increase of basicity from 0.6 to 1.2,the break temperature of mold slag gradually increases from 1 128 ℃ to 1 264 ℃,the proportion of precipitated CaTiO3 crystals gradually increases with the in-crease of basicity,and the intensity of XRD diffraction peak is significantly enhanced.In terms of the slag micro-structure,with the increase of basicity,the number of simple structural units Al-O-and Q0,Q1 in the slag increa-ses,the number of complex structural units Q2 and Q3 decreases,and the overall polymerization degree and com-plexity of the slag show a downward trend,which has the same variation of the viscosity.On the whole,increase of basicity will lead the slag viscosity to decrease,melting point to increase and crystallization property to increase,therefore,reasonable control of mold slag basicity can optimize its basic properties,which is conducive to continuous casting process stability of high-titanium steel.
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