以KR→BOF→RH→CC流程生产的低碳铝镇静钢,在转炉流程后采用2种不同脱氧工艺:出钢添加部分铝预脱氧,RH真空循环利用钢中碳脱氧,后加铝强脱氧(工艺Ⅰ);出钢加铝强脱氧,RH真空循环处理(工艺Ⅱ)。对两种脱氧工艺出钢后的顶渣改质效果进行对比分析,结合全氧分析,利用ASPEX扫描电镜对两种工艺下RH真空处理过程的夹杂物和铸坯内外弧表层夹杂物的形貌、成分、数量和尺寸进行系统研究。结果表明,工艺Ⅱ的顶渣改质效果优于工艺Ⅰ;经过RH真空处理,两种工艺均可以明显地去除20μm以上的夹杂物;在RH精炼阶段、铸坯及热轧板表层的夹杂物尺寸、数量密度以及总氧控制方面,工艺Ⅱ优于工艺Ⅰ。
Two different deoxidation methods for low carbon aluminum killed (LCAK) steel produced by KR-BOF-RH- CC process were compared: a part of aluminum were added when tapping, followed by deoxidation with carbon in RH process, and then fully deoxidated by aluminum (method I ); full deoxidation by aluminum when tapping, followed by pure cycling and alloying in RH degasser (method II). Apart from total oxygen content measurement and analysis of top slag modification, the morphology, composition, and size of non-metallic inclusions during RH refining process and sur- face layer of continuously-cast slabs and hot rolled coils were analyzed with Automatic Feature Analysis (AFA) equipped on ASPEX PSEM Explorer. The results show that method II is superior to method I in refining slag modification. Fur- thermore, the inclusions larger than 20 μm are well removed during RH process and method II is also more advantageous than method I in controlling the size of inclusions in the slab and on hot rolled plate surface, as well as number density and total oxygen content.