BOF→RH→CSP工艺生产含钛IF钢浸入式水口结瘤机理研究

Investigation on clogging mechanism of submerged entry nozzle for Tibearing IF steel during BOF→RH→CSP process

针对BOF→RH→CSP工艺生产含钛IF钢浸入式水口结瘤问题,采用扫描电镜、能谱分析等方法,分析了IF钢浇铸过程水口结瘤物的组成,结合中间包夹杂物的特性,阐明了水口结瘤的机理。结果表明:钛元素的存在一方面使钢水中Al_2O_3夹杂物不易碰撞长大,另一方面减小了钢液、耐材和夹杂物之间的润湿角,容易造成水口结瘤;结瘤物初始沉积层主要为钢水与水口耐材反应生成的以Al_2O_3为主的复合氧化物;而结瘤物主体层主要来源于钢水中的夹杂物,为低变性的MgO·Al_2O_3尖晶石或Al_2O_3,且含有钢滴;夹杂物沉积进而烧结成疏松的网状层,使钢水更易粘附从而加剧了水口结瘤速度。研究结果可为优化工艺参数、提高BOF→RH→CSP工艺连浇炉数和产品质量提供可靠的理论指导。

In order to investigate the clogging mechanism of submerged entry nozzle during casting Tibearing IF steel by BOF-RH-CSP process. The composition of clogs on submerged entry nozzle was studied by scanning election microscopy（ SEM）,energy dispersive spectroscopy（ EDS）. Finally,the clogging mechanisms of submerged entry nozzle were elucidated by combining with the characteristics of inclusion in tundish. The investigated results indicated that the clogging easily occurs because that wetting angle was decreased due to containing titanium in molten steel. The clogs close to the inner surface of submerged entry nozzle,which was composite oxide of Al_2O_3-CaO-SiO_2-MgO but mainly consists of Al_2O_3,was resulted from reaction between refractory material of SEN and acid-soluble aluminum in molten steel. However,the clogs close to molten steel comes from the deposition of inclusions containing Al_2O_3 or spinel of MgO ·Al_2O_3 and iron particles. The rate of clogging was increased because that the molten steel easily adhered to net sintered inclusions. The studied results will provide theoretical guidance for rising the continuous casting heats of tundish and improving the quality of products by means of optimizing the process parameters.