管线钢浇次头坯夹杂物控制

Study on How to Control Inclusions in the First Slab in Casting Sequence of Pipeline Steel

研究了管线钢浇次头坯夹杂物的主要来源及控制措施。采取将浇次头坯轧制成热轧板和在热轧板取样分析的试验方案,得出热轧板和铸坯夹杂物分布。结果表明开浇初期4 m以内的头坯存在2级以上的B类夹杂物和保护渣卷渣。开浇初期钢水注流的二次氧化是导致头坯夹杂物超标的主要因素。提出开浇初期增加吹氩量和适当延长吹氩时间能够较好的排除中包空气,对降低注流二次氧化起到很好作用。

The main sources of inclusions and measures for controlling them in first slab in casting pipeline steel are studied.The technical solution for rolling first slab into hot-rolled sheets is made,and then sampling from the sheets in order to analyze the distribution of inclusions in the slabs and sheets.The results show that Grade 2 and above B-type inclusions and entrapped slag of mould powders exist in the range of 4 m long first slab in starting casting.Too many inclusions in the slabs are mainly caused by reoxidation of molten steel flow in the early stage of casting.Accordingly measures for fixing the air excess of tundish and decreasing reoxidation degree of molten steel flow are proposed,which can increase the volume and extend the time of blowing argon appropriately.