含钛夹杂物对连铸保护渣性能的影响

含钛钢连铸过程中析出氮化钛夹杂,并参与渣-金界面反应,严重恶化传统含钛钢连铸保护渣的理化性能。研究了不同含量的TiN和TiO₂对不同碱度保护渣的熔点、黏度、结晶比例以及凝固温度等性能的影响规律。测试结果表明,TiN对CaO-SiO₂基保护渣的性能影响最大,随着渣中TiN含量的升高,保护渣的黏度、结晶比例和凝固温度大幅度升高;当TiN质量分数大于5%时,熔点大幅升高。TiO₂对CaO-Al₂O₃基保护渣的性能影响最大,当TiO₂质量分数小于4%时,可小幅度降低保护渣的黏度和凝固温度;当TiO₂质量分数大于10%时,渣中钙钛矿成为主要析出物相,熔渣的性能严重恶化,影响对坯壳的润滑作用。通过对比3种不同碱度的基础渣发现,CaO-SiO₂-Al₂O₃基保护渣具有较好吸收含钛夹杂物的能力。

Effect of titanium inclusions on performance of mold flux during continuous casting of Ti-bearing steel

During the continuous casting process, titanium nitride inclusions are precipitated in the Ti-bearing steel and participate in the steel-slag interface reaction, which seriously deteriorates the physical and chemical properties of the traditional mold flux for Ti-bearing steel. This study measured the influence of different contents of TiN and TiO₂ on the melting temperature, viscosity, crystallization ratio and solidification temperature of mold fluxes with different basicity. The results show that TiN has the greatest impact on the performance of CaO-SiO₂ based mold fluxes. With the increase of TiN content, the viscosity, crystallization ratio and solidification temperature of mold fluxes extremely increase. When the mass fraction of TiN is greater than 5%, the melting point increase sharply. The properties of CaO-Al₂O₃ are sensitive to the TiO₂ content. When TiO₂ is less than 4%, the viscosity and solidification temperature of the mold flux can be reduced slightly. When the TiO₂ is larger than 10%, the perovskite is the main precipitated phase in the mold flux and the performance of mold flux is seriously deteriorated, which is not conducive to the lubrication effect on the billet shell. By comparing three basic mold fluxes with different basicity, it is found that CaO-SiO₂-Al₂O₃-based mold can absorb titanium inclusions preferably.