铝镇静特殊钢B类非金属夹杂物原因分析与控制

对某钢厂复吹转炉→LF钢包精炼→RH真空处理→连铸的冶金流程生产的棒材的超标B类非金属夹杂物通过扫描电镜和能谱进行形貌和化学成分分析，夹杂物主要分为2类，即CaO- Al2O3- SiO2- MgO- (F)系与Al2O3系。通过夹杂物的化学成分和形貌确定超标的B类非金属夹杂物主要来源分别是连铸钢包下渣和连铸过程二次氧化等。通过提高连铸钢包长水口氩封氩气流量、优化长水口“碗口”结构和调整连铸钢包下渣系统灵敏度等方面，棒材的B类非金属夹杂物的平均合格率从93.2%提高到97%以上。

Cause analysis and control of B type non- metallic inclusions of Al killed special steel

Large size B type non- metallic inclusions were detected in bars produced by the steelmaking process flow "BOF- LF ladle refining- RH vacuum treatment- casting". The morphology and chemistry of the large size B type non- metallic inclusions were analyzed by scanning electron microscopy and energy dispersive spectrometer, and the results showed that the defects mainly included two types: CaO- Al2O3- SiO2- MgO- (F) system and Al2O3 system. Through the morphology and chemistry of the inclusions, it could be concluded that the main resource of the B type non- metallic inclusions were the slag carried out during continuous casting and re- oxidation during continuous casting. Through increasing the long nozzle argon sealing flow rate, optimizing the SEN structure and adjusting the sensitivity of the slag detection system, the acceptable rate of B type non- metallic inclusions was increased from 93.2% to 97%.