Abstract: In order to reduce inclusions in steel and modify inclusions to prevent nozzle clogging during casting process, the equilibrium theimodynamic calculations of Ca-Al, Al-O, Al-S and Ca-S, and the analysis of oxygen and nitrogen of 5 heats 100 t LF of cold heading steel SWRCH22A (/% ： 0.18 ~0. 20C, 0. 44 ~0. 62Si, 0. 85 ~0. 89 Mn, 0.012 ~ 0. 015P, 0. 006 ~ 0. 009S, 0 ~ 0. 004Ca, 0.000 7 -0.001 0B, 0. 011 ~ 0. 088Als) by calcium treatment on inclusions in steel have been carried out. The equilibrium curves of [Ca]-[Al],a[O]-[Al] and [S] -[Al] at 1 873 K and [ Ca] -[ S] at 1 823 ~ 1 923 K are obtained and compared to corresponding measured data of 5 heats. By analysis the optimized LF refining process: (1) end refining slag- MgO = 6% , SiO₂ <6% and CaO/Al₂O₃ =1.6 ~1.8; (2) amount of BOF tapping slagging being about 700kg, amount of end refining slag being about 2 000 kg; (3) according to the aim end refining slag with CaO/Al₂O₃ = 1. 6 ~ 1. 8 to define the amount of charging slag materials; and (4) avoiding the boiling of liquid steel during feeding calcium wire process and the oxidation of liquid during process of end refining to tundish.

摘要： 为减少钢中夹杂物和对夹杂物变性处理,防止连铸水口结瘤,对100 t LF 5炉SWRCH22A冷镦钢（/%:0.18~0.20C，0.44~0.62Si，0.85~0.89Mn，0.012~0.015P，0.006~0.009S，0~0.004Ca，0.000 7~0.0010B，0.011~0.088Als）夹杂物钙处理进行了Ca-Al,Al-O,Al-S,Ca-S平衡热力学计算和氧氮分析。得出1 873 K[Ca]-[Al],a[O]-[Al]和[S]-[Al]平衡曲线,1 823~1 923 K[Ca]-[S]平衡曲线,和5炉钢对应的实测值。通过分析,得出优化LF精炼工艺:（1）精炼终渣MgO=6%、SiO₂<6%、CaO/Al₂O₃=1.6~1.8;（2）转炉下渣量700 kg左右,精炼终渣量2 000 kg左右;（3）根据精炼终渣CaO/Al2O3=1.6~1.8的目标来决定造渣料的加入量;（4）避免喂钙线时钢水剧烈翻腾,并防止精炼结束到中间包过程钢水的氧化