BOF-LF-CC生产SWRH82B硬线钢的洁净度研究

Cleanliness study of SWRH82B hard wire steel produced by BOF-LF-CC processes

采用系统取样与实验室综合分析,对BOF-LF-CC工艺生产的SWRH82B钢洁净度衍变规律进行研究.结果表明,钙处理后钢中T[O]和显微夹杂物数量显著下降,轻微增氮;浇铸过程增氧增氮严重;铸坯中<5μm显微夹杂占97%,主要是棱角分明的纯Al_2O_3夹杂,球状复合氧化物与CaS和MnS的复合夹杂,简单氧化物或氮化物与MnS的复合夹杂;LF精炼后钙处理,脱氧显著,但使得铸坯中出现很多Al_2O_3硬性夹杂,对SWRH82B盘条质量造成严重的危害;中间包结构不合理,卷渣、内衬侵蚀和二次氧化严重,连铸过程钢液洁净度下降.

The cleanliness evolution of SWRH82B steel produced by the BOFLFCC process was studied by systematic sampling and lab comprehensive analysis. The results show that the content of oxygen and the number of micro-inclusions significantly decrease after calcium treatment,while the content of nitrogen in molten steel slightly increases. Both the contents of oxygen and nitrogen sharply increase during the casting process. 97% of the micro-inclusions in casting billets are smaller than 5 μm. They mainly include trenchant angularity single Al_2O_3 inclusions,spherical complex inclusions of oxides with Ca S and Mn S,and complex inclusions of simple oxides or nitrides with Mn S. Calcium treatment after LF refining removes oxygen from molten steel efficiently,but increase the amount of Al_2O_3 inclusions in casting billets,which is harmful to the quality of SWRH82B steel. Due to serious lag entrapment,refractory erosion and reoxidation caused by unreasonable tundish structure,the cleanliness of liquid steel decreases.