210 t BOF-RH-CC炼钢过程无取向硅钢XG800WR洁净度的试验研究

两炉次无取向硅钢XG800WR(/%:0.003～0.004C、0.71～0.75Si、0.32～0.33Mn、0.004～0.007S、0.016P)的炼钢流程为铁水预处理(KR)-210 t顶底复吹转炉-钢包吹氩-RH脱碳精炼-230 mm×1220 mm板坯连铸。53 t中间包钢水过热度为25～30℃,钢包到中间包采用长水口全程吹氩保护浇铸,中间包至结晶器采用浸入式水口浇铸。结果表明,在RH、中间包、结晶器过程中钢中总氧以及夹杂物数量和尺寸均明显降低;但在钢包到中间包过程TO]、N]和钢中夹杂物数量增加,说明长水口浇铸过程存在二次氧化。连铸坯中TO]、N]平均他分别为11×10^-6和30×10^-6,显微夹杂物数量平均为4个/mm~2。铸坯中的显微夹杂物主要为3～5 μm的AIN,同时存在少量的MnS、Al₂O₃·AIN和Al₂O₃·MgO·MnS。

Examination and Study on Cleanliness of Non-Oriented Silicon Steel XG800WR in 210 t BOF-RH-CC Steelmaking Process

The steelmaking flow sheet for two heats non-oriented silicon steel XG800WR（/%:0.003～0.004C. 0.71～0.75Si,0.32～0.33Mn,0.004～0.007S,0.016P） is hot metal pretreatment（KR）-210 t top and bottom combined blown converter-ladle argon blowing-RH decarburization refining-230 mm×1 220 mm slab casting.The superheating extent of liquid in 53 t tundish is 25～30℃,whole casting is shielded by blowing argon with long nozzle from ladle to tundish and the submerged nozzle is adopted in casting from tundish to mold.Examination results show that the total oxygen content TO]in liquid and the amount and size of inclusions in steel obviously decrease during RH,tundish and mold process,but the TO],N]and amount of inclusions increase from ladle to tundish process,it indicates that there is secondary oxidation of liquid in casting process with long nozzle.The TO]andN]in casting slab are respectively 11×10^-6 and 30×10^-6,the average amount of micro-inclusions is 4 inclusions per square mm.The main micro-inclusions in casting slab are 3～5μm AlN with minor MnS,Al₂O₃·AlN and Al₂O₃·MgO·MnS.