冷轧薄板超低碳钢精炼双联工艺研究及应用

Research and application of refining duplication process for cold rolled ultra low carbon steel

通过对超低碳钢RH及连铸中间包取样数据进行分析,发现RH升温吹氧量的增加导致全氧含量、渣中TFe含量升高,w(CaO)/w(Al2O3)逐渐降低,对控制大尺寸Al2O3夹杂物数量比例及中包全氧含量十分不利,因此采用LF+RH双联工艺取消吹氧升温,提高钢水纯净度。该工艺中转炉低温低氧出钢,LF优化钢包底吹强度、给电升温时间,在给电结束后钢水氧质量分数控制在0.033%~0.045%,改质后钢水氧质量分数控制在0.025%~0.030%。RH取消吹氧升温,脱碳结束氧质量分数控制在0.015%~0.020%,RH出站渣中w(TFe)≤5%,w(CaO)/w(Al2O3)稳定控制在1.3~1.5。在工业生产应用后,超低碳钢双联工艺路线下的夹杂物控制水平可以满足冷轧汽车外板要求。

By analyzing the sample data of RH and tundish of ultra-low carbon steel,it is found that the increase of RH blowing oxygen led to the increase of terminal oxygen content and TFe content in slag,w(CaO)/w(Al2O3) decreased gradually,which was very disadvantageous to control the number of large-size Al2O3 inclusions and the total oxygen content in tundish. Therefore,the LF+RH dual process was adopted to eliminate RH blowing oxygen,improve the purity of steel. In this process,low temperature and low oxygen content were applied in tapping process of converter,and the bottom blowing strength of the ladle and the heating time were optimized in LF. After power supply the oxygen content in the steel was controlled at 0.033 %—0.045 %,and 0.025 %—0.030 % after slag modification. After RH cancelling oxygen blowing,terminal oxygen content was control at 0.015 %—0.020 %, w(TFe)≤5 % in RH outbound slag,w(CaO)/w(Al2O3) was controlled in 1.3—1.5 stably. After application in industrial production,the inclusion control level of ultra-low carbon steel dual process route could meet the requirements of cold-rolled automobile outer plate.