高钛钢连铸结晶器内“结鱼”的形成

Study on floater formation in continuous casting mold of high-titanium steel

针对高钛钢连铸结晶器内“结鱼”问题,采用SEM-EDS分析方法,观察了结鱼物和铸坯缺陷的形貌,测定了结鱼物和铸坯缺陷化学组成,分析了高钛钢内TiN夹杂物形成的热力学条件,探讨了结鱼物形成的机制。结果表明:高钛钢连铸坯缺陷样主要由钢基体、孔洞、保护渣、钙钛矿和TiN等物质组成,其与结鱼物的组成较为接近,缺陷样内存在着7~8μm的TiN聚集现象;当钢中全氮质量分数低于46×10^(-6)时,高钛钢钢液的TiN夹杂物生成与非稳态生产有关;高钛钢结晶器内的结鱼物和连铸坯夹渣缺陷的产生与钢液中TiN的生成及其在钢渣界面处聚集有关。

In order to solve the problem of the"floater"formation in the continuous casting mold of high-titanium steel,the morphology of the floater and defects from the slab were observed and chemical compositions were obtained through the analysis of the SEM-EDS.The formation of TiN inclusion in high-titanium steel was analyzed through the thermodynamic calculation,and the formation mechanism of floater was discussed.Results showed that the defect sample of high titanium steel billet was mainly composed of steel matrix,holes,mold slag,perovskite and TiN,whose constituent was similar to that of the floater,and the aggregation of TiN with the size of 7-8μm in the defect sample was observed.With the mass fraction of total nitrogen in steel below 46×10^(-6),the formation of TiN inclusions in the molten steel of the high-titanium steel was related to the unsteady production.The formation of the floater in the steel and the occurrence of the residue defect at the surface of the billet were related to the formation of TiN in liquid steel and its gradual accumulation at the steel-slag interface.