100t LF精炼渣碱度和Al_2O_3含量对65Mn钢夹杂变质和去除效果的影响

100 t LF原精炼终渣(/%:53.8CaO,8.16MgO,16.6SiO_2,17.45Al_2O_3,1.44TFe,1.26S,R3.08)优化成终渣(/%:51.3CaO,6.36MgO,25.0SiO_2,6.73Al_2O_3,2.96TFe,0.76S,R2.05)后,通过降低碱度和渣中Al_2O_3含量,65Mn钢(/%:0.63~0.65C,0.19~0.22Si,0.92~0.96Mn,0.005~0.006S,0.021~0.022P,0.003 5~0.0037T[O])中的夹杂物当量个数由18.4个/mm^2减少到11.3个/mm^2,其平均直径由8.4μm减小到4.5μm。相比原精炼渣系,采用优化渣系的65Mn在LF出站时的钢中Al_2O_3由5.9个/mm^2降低到1.7个/mm^2;其CaO-SiO_2-Al_2O_3和CaO-SiO_2-Al_2O_3-MgO复合夹杂物中Al_2O_3含量由38.3%~44.7%降低到17.5%~28.7%。B类Al_2O_3夹杂物不合格的卷数由6%降至3%。

无铁水预处理超低硫管线钢L245NCS的生产实践

LF精炼渣系控制在CaO 50%~58%、Al2O3 27%~35%、SiO2≤10%、MgO≤10%、(TFe+MnO)≤1.0%,MI范围0.25~0.30,R范围8~9.5,(CaO)/(Al2O3)范围1.6~1.9,Als含量0.010%~0.020%。渣系脱硫效果好,化渣快,可在无铁水预处理的情况下,满足生产成品S≤15×10-6超低硫管线钢L245NCS的要求。