萤石含量对连铸保护渣结晶性能的影响

Effect of Fluorite Content on Crystallization Properties of Casting Mould Fluxes

通过热丝法得出保护渣连续冷却转变（CCT）和时间-温度转变（TTT）曲线,并用偏光显微分析和X-射线衍射分析方法研究了萤石含量（8%~16%）对碱度1.0的薄板坯连铸结晶器保护渣结晶性能的影响。结果表明,萤石含量每增加2%,保护渣的临界冷却速度平均增加2.5℃;同一冷却速度下,随保护渣中萤石含量的增加,结晶温度升高,结晶率增大,有利于提高界面热阻,控制渣膜传热,减少铸坯表面裂纹产生;因萤石含量超过14%时,渣膜中大量生成结晶矿物枪晶石,对连铸润滑要求较高的钢种,应控制萤石含量≤14%。

With using hot wire method to get the mould fluxes continuous cooling transformation（CCT） and time-temperature transformation（TTT） curves and using polarizing microscope combined with X-ray diffraction analysis,the effect of fluorite content（8%~16%） on crystallization properties of thin slab casting mould fluxes with basicity 1.0 has been studied.Results show that with increasing fluorite content by each 2%,the average critical cooling rate increases by 2.5℃;at same cooling rate with increasing fluorite content in mould fluxes,the mould fluxes crystallization temperature raises and the crystallization rate increases,they are favourable to improve the interfacial thermal resistance,control the heat transfer of slag film and decrease the forming of surface crack of casting slab;as the fluorite content is more than 14%,large amount of crystalline mineral cuspidine forms in slag film,for the steel grades with higher casting lubricating requirement,it should be to control the fluorite content in fluxes no less than 14%.