BOF-LF-CSP工艺生产SPHC钢的夹杂物演变

 通过热力学计算及转炉、LF炉、中间包、铸坯的系统取样与SEM、EDS等检测，对BOF-LF-CSP工艺生产的SPHC钢夹杂物在各工序的种类、数量、变性及组成进行了研究。结果表明，在BOF-LF-CSP过程中, 转炉终点夹杂物以Al2O3为主，在LF炉钙处理后钢水Al2O3夹杂的质量分数降低到铝处理后时的50%，出LF炉时钢中剩余的Al2O3夹杂基本完成了球化变性，并以铝酸钙复合物或硅酸盐结合的镁铝钙复合物为主，球化率约为72%；铸坯内夹杂物的平均粒径为5. 4μm、球化率为75. 8%。Al2O3经历了①Al2O3→CaO·6Al2O3→CaO·2Al2O3或CaO·Al2O3→12CaO·7Al2O3或CaO·3Al2O3；②Al2O3→MgO-Al2O3→MgO-Al2O3-CaO→MgO-Al2O3-CaO-SiO2的演变，正确合理的精炼工艺会使夹杂物充分上浮、球化及变形，提高钢水可浇性及钢材性能。

Evolution of Non-Metallic Inclusions in SPHC Steel Produced by BOF-LF-CSP Process

By the thermodynamic calculation, systematic sampling from BOF, LF, tundish and the casting billets and SEM, EDS analysis, the evolution of non-metallic inclusions (include the type, amounts, property and components) in SPHC steel produced by BOF-LF-CSP process was investigated. The results show that in BOF-LF-CSP process, the type of inclusions at BOF end is mainly Al2O3. After calcium treatment in LF, the Al2O3 inclusions decreased to the 50% of addition Al time. The remaining Al2O3 inclusions of steel is completed the spheroidization after the process of LF. Mainly it is calcium aluminum composite or silicate and Mg-Al-Ca composite. The sphericity rate is 72%. The inclusions average size reach 5. 4μm and sphericity rate is 75. 8% in the slab. The evolution processes of Al2O3 inclusion are as follows: ① Al2O3→CaO·6Al2O3→CaO·2Al2O3 or CaO·Al2O3→12CaO·7Al2O3 or CaO·3Al2O3; ② Al2O3→MgO-Al2O3→MgO-Al2O3-CaO→MgO-Al2O3-CaO-SiO2. Reasonable and right refining process will enable the inclusion fully float, spheroidization and transformation, improve the steel fluidization and property.