ABSTRACT

The evolution of inclusions during the refining and casting process was investigated on an industrial scale to clarify the quantity and distribution of non-metallic inclusions for 321H stainless steel. The analyses showed that Al₂O₃-SiO₂-MnO-CaO and Al₂O₃ as the main types of inclusions at the late of AOD and VOD, respectively. Pure titanium nitride and titanium nitride with oxide as the nuclei dominated the inclusions at the late of LF. The types of inclusions in mold and slab were similar to those obtained at the late of LF, while titanium nitride inclusions in slab were higher in numbers and larger in size. The titanium nitride inclusions precipitating with MgO-Al₂O₃-CaO-(TiO₂) nuclei showed a higher number density and area fraction than other oxide inclusions. The calcium treatment of molten steel was optimized by FactSage software and it was necessary to accurately control the calcium content in molten steel before titanium addition.

摘要

在工业规模上研究了精炼和铸造过程中夹杂物的演变，以明确 321H 不锈钢中非金属夹杂物的数量和分布。分析表明，AOD和VOD后期的夹杂物类型分别以Al ₂ O ₃ -SiO ₂ -MnO-CaO和Al ₂ O _3为主。LF后期夹杂物以纯氮化钛和以氧化物为核的氮化钛为主。结晶器和铸坯中的夹杂物类型与LF后期的夹杂物相似，但铸坯中的氮化钛夹杂物数量较多，尺寸较大。_{MgO-Al 2} O ₃沉淀的氮化钛夹杂物-CaO-(TiO ₂ )核表现出比其他氧化物夹杂物更高的数密度和面积分数。利用FactSage软件对钢水的钙处理进行优化，在添加钛之前需要准确控制钢水中的钙含量。