Abstract: The amount and distribution of inclusions in casting slab of ultra-low carbon steel ( ≤0. 01% C) processing in 210 t ladle with and without adding modifying agent (/% : 38 ~43Al, 20~30Al₂O₃, 27 ~ 31 CaO, ≤6SiO₂, ≤6MgO) to ladle top slag have been examined and analyzed, and the effect of modifying agent on oxygen equilibrium between steel and slag and inclusions in casting slab is studied by thermodynamic analysis. Results show that the ingredient of refining slag sample for ladle top slag without adding modifying agent is (/% ) 25. 55 ~ 39. 68CaO, 8. 51 ~15. 14SiO₂, 6. 34 ~ 27.09MgO, 5. 92 ~6. 54Al₂O₃, 17. 32 ~22, 24FeO, 3. 86 ~7. 35MnO, and ingredient of refining slag sample for ladle top slag with adding modifying agent is (/% ) 34.36 ~ 40. 43CaO, 7. 69 ~11.47SiO₂ , 6. 42 ~7. 31MgO, 8.31 ~ 25. 54Al₂O₃, 11.94 ~ 20. 78FeO, 2. 17 ~ 2. 63MnO； with using ladle top slag modification treatment, the actual activity coefficient a_(FeO) in slag is less than that in equilibrium with dissolved oxygen in steel led to oxygen diffusion from steel to slag through the interface of metal-slag, thus to lower the activity of oxygen in liquid, obviously improve the cleanliness of liquid and decrease the amount and size of inclusions in casting slab, and markedly reduce the nozzle clogging occurrence. Besides, although the decrease of a_(FeO) in slag is small, whereas the activity of oxygen in liquid decreases significantly.

摘要： 检测分析了加改质剂（/%:38~43Al,20~30Al₂O₃,27~31CaO,≤6SiO₂,≤6MgO）改质210 t钢包顶渣前后超低碳钢（≤0.01%C）连铸坯中的夹杂物数量和尺寸分布,通过热力学分析,研究了改质剂对钢渣间氧平衡以及连铸坯中夹杂物的影响。结果表明,钢包顶渣改质前的精炼渣样成分为（/%）25.55~39.68CaO,8.51~15.14SiO₂,6.34~27.09MgO,5.92~6.54Al₂O₃,17.32~22.24FeO,3.86~7.35MnO,改质后渣样成分为（/%）34.36~40.43CaO,7.69~11.47SiO₂,6.42~7.31MgO,8.31~25.54Al₂O₃,11.94~20.78FeO,2.17~2.63MnO;采用钢包顶渣改质处理,实际渣中a_(FeO)小于与钢液中氧相平衡的a_(FeO),引起了钢液中的氧通过渣金界面向渣中扩散,从而降低了钢液中氧活度,显著改善钢液的洁净度和降低连铸坯中的夹杂物数量和尺寸,水口结瘤得到明显改善;同时,虽然渣中的a_(FeO)下降较小,但钢液中氧活度得到了明显降低。

关键词: 顶渣改质, 杂物, 超低碳钢, 氧活度, 水口堵塞