中薄板坯流程生产IF钢中包水口结瘤控制

采用扫描电镜、能谱分析等方法,对BOF-RH-CC中薄板坯流程生产含钛IF钢浸入式水口结瘤的原因进行了分析。结果表明,含钛IF钢水口结瘤的原因为水口本体内部的C与SiO2发生反应产生氧化性气体,氧化性气体和钢水中的Al]、Ti]反应在水口内壁上形成反应层,反应层促进了钢水中原有的Al2O3和Al-Ti-O复合夹杂物快速向水口内壁沉积。Ti的存在加重了水口结瘤的发生。以全流程氧位控制为目标,通过转炉终点控制、RH精炼、顶渣改质、中薄板坯连铸等工艺优化,使RH出站钢水TO]质量分数控制在35×10^-6以下,中包钢水TO]质量分数控制在30×10^-6以下,水口结瘤现象得到明显改善,单支水口平均连浇炉数由1.2炉提高至3炉,单支水口连浇时间提高到177 min。

Clogging control of submerged entry nozzle during IF steelproduction by middle -thin slab process

The causes of SEN clogging during Ti-bearing IF steel production in the process of BOF-RH-middle-thin slab caster were analyzed by scanning election microscopy (SEM), energy dispersive spectroscopy (EDS). The analysis shows that the reason for SEN clogging of titanium containing IF steel nozzle is that the reaction of oxidizing gas and ［Al］ and ［Ti］ in molten steel forms a reaction layer on the inner wall of the nozzle, and the reaction layer promotes the original Al2O3 and Al-Ti-O composite inclusions in the molten steel deposits to SEN inner wall quickly. The presence of ［Ti］ exacerbates the occurrence of SEN clogging. With the goal of oxygen potential control in the whole process, the T［O］ content of RH molten steel is controlled at 35×10-6 by process optimization of converter end point control, RH refining, top slag upgrading, middle thin slab continuous casting, etc. The mass fraction of T［O］ in the steel is controlled to be less than 30×10-6, and SEN clogging of the nozzle is obviously improved. The average heats of continuous castings of the single nozzle is increased from 1.2 to 3. The pouring time of single nozzle is increased to 177 min.