高碱度中间包覆盖剂对改善0Cr18Ni9不锈钢洁净度的影响

0Cr18Ni9奥氏体不锈钢的生产流程为铁水脱磷预处理-75 t转炉-VOD-LF-200 mm×1 200 mm坯连铸工艺。分析了连铸过程20 t中间包覆盖剂(/%:40.54CaO,28.89Al₂O₃,7.8SiO₂,6.32MgO,1.84C,碱度5.2)组分变化,及钢中氧、夹杂物去除效果。结果表明,采用高碱度中间包覆盖剂时,多炉连浇后覆盖剂吸收钢中硅酸类夹杂物效果明显,0Cr18Ni9不锈钢中平均氧含量由LF钢水中的56.5×10^-6,降低到中间包钢水中的37.5×10^-6和铸坯的33.3×10^-6,铸坯中夹杂物数量及大小较LF后有明显降低,高碱度中间包覆盖剂对去除20μm以上的大颗粒夹杂效果明显。

Influence of High Basicity Tundish Shielding Agent on Improvement of Cleanliness of Stainless Steel 0Cr18Ni9

The production flowsheet of austenite stainless steel 0Crl8Ni9 is hot metal dephosphorizing pretreatment- 75 t BOF-VOD-LF-200 mm x 1 200 mm slab casting process. The change of ingredient of 20 t tundish shielding agent (/% : 40.54CaO, 28.89Al₂O₃,7.8SiO₂, 6.32MgO, 1.84C, basicity 5.2) during continuous casting process, and removal effect of oxygen and inclusions in steel are analyzed. The results show that with using high basicity tundish shielding agent after multi-heats continuous-continuous casting the effect of shielding agent absorbing silicate type inclusions is obvious, the average oxygen content in steel decreases from 56. 5 x 10^-6 after LF refining to 37. 5 x 10^-6 in tundish and to 33.3 x 10^-6 in casting slab of stainless steel 0Cr18Ni9； as compared with end LF the amount and size of inclusions in casting slab decrease markedly, and the high basicity tundish shielding agent has an obvious effect on removal of larger inclusions with size more than 20 μm.