Abstract: The crystallization phenomenon of continuous casting mold flux vitreous membrane in reversion-heating process has important influence on thermal resistance of flux film. The influence of basicitv (R 0.8~1.4) on crystallization rate of casting mold flux (/% ：28.22〜49.73CaO, 35.52SiO₂, 4.00Na₂O, 2.14MgO, 14.55A1₂O₃, 0.72TiO₂, 0.93Fe₂O₃, 0.32K₂O, 0.32MnO₂, 2.03CaF₂, 6.18C) has been studied by using the SHTT-II melting crystallizing temperature measuring instrument and metallographic microscope to establish the TTT curves, the nucleation activation energy of mold flux with different basicity is calculated and the morphology of surface of mold flux with different basicity reversionheating at 800 °C , 900 °C and 1000 °C is observed. The test results show that with increasing basicity the recrystallization temperature of mold flux and the nucleation activation energy continuously decrease ； with reversion-heating temperature rise of vitreous flux film, the bulges and pits at surface and a mass of defects in inner of film occur. The suitable range of basicity of flux is put forward that is 0.80~0.95 for low carbon steel,≥l.2 for medium-carbon steel and 0.75〜0.90 for high carbon steel.

Key words: Continuous Casting, Mold, Flux film, Basicity, Single Hot Thermocouple Technique ( SHTT), Crystallization Rate

摘要： 连铸保护渣玻璃体渣膜回温结晶现象对渣膜的热阻有重要影响。采用SHTT-Ⅱ型熔化结晶温度测定仪并结合金相显微镜,研究碱度（R 0.8~1.4）对保护渣（/%:28.22~49.73CaO，35.52SiO₂，4.00Na₂O，2.14MgO，14.55Al₂O₃，0.72TiO₂，0.93Fe₂O₃，0.32K₂O，0.32MnO₂，2.03CaF₂，6.18C）的结晶率的影响,构建了TTT曲线,计算了不同碱度下保护渣形核活化能,观察了在800,900,1000℃回温处理下不同碱度保护渣表面形貌。实验结果表明,随着碱度增加保护渣结晶温度和形核活化能不断降低;随着玻璃体渣膜回温处理温度的升高,玻璃渣膜表面出现凸起、凹坑以及大量的内部缺陷;提出合适的碱度范围为:低碳钢0.80~0.95,中碳钢≥1.2,高碳钢0.75~0.90。

关键词: 连铸, 结晶器, 渣膜, 碱度, SHTT热丝法, 结晶率