Cleanliness of aluminum-killed ultra-low carbon steel produced through BOF–RH–CC and BOF–LF–RH–CC was comparatively investigated by nitrogen–oxygen analysis, SEM analysis and thermodynamic calculation to seek for an optimum refining process. The results show that the non-metallic inclusions with area above 8 μm² could be removed obviously in both the refining processes. Compared with BOF–RH–CC process, in RH refining stage, the size of inclusion and total oxygen control were better than the original process. Furthermore, BOF–LF–RH–CC process reduced the inclusion area ratio, the proportion of single inclusion area of < 8 μm² increased from 85 to 95%, the proportion of Al₂O₃ inclusion less than 5 μm² increased from 50 to 70%. Meanwhile, the desulfurization effect became pronounced and the temperature control of the double refining process was more stable than that of the original process.

通过氮气-氧气分析，SEM分析和热力学计算，对通过BOF-RH-CC和BOF-LF-RH-CC生产的铝杀死超低碳钢的清洁度进行了比较研究，以寻求最佳的精炼工艺。结果表明，与区域内的非金属夹杂物之上为8μm ²可在精炼过程都明显除去。与BOF–RH–CC工艺相比，在RH精炼阶段，夹杂物的大小和总氧控制均优于原始工艺。此外，BOF-LF-RH-CC工艺降低夹杂物的面积比，<8微米的单夹杂面积的比例²从85提高到95％，Al的组成比₂ ö ₃夹杂物超过5μm以下²从50％增加到70％同时，脱硫效果显着，双精制过程的温度控制比原始过程稳定。