Abstract: Based on the process of 50 t EAF-LF-VD for gear steel 28MnCr5 (/% : 0. 28C, 0. 09Si, 0. 70Mn, 0. 015P, 0. 027S, 0. 95Cr) , the effect of proportion of each ingredient in slag on melting point of CaO-SiO₂-Al₂O₃-MgO refining slag series has been studied by using thermodynamic calculation software FactSage, to get optimum proportion of ingredients in order to control the inclusions in low melting point region and remove out. Results show that as (CaO) / ( SiO₂) W 1, the percentage of low melting point region to whole phase diagram area is larger and as CaO content in slag ( CaO) is 30%, the percentage of low melting point region to whole phase diagram area is maximum i. e. 53. 2% ； the optimum ingredient of quaternary refining slag series is (/%) 30CaO-30SiO2-25Al₂O₃-15MgO.

Key words: Gear Steel 28MnCr5, Refining Slag, Phase Diagram, Low Melting Point

摘要： 以28MnCr5齿轮钢(/%:0.28C、0.09Si、0.70Mn、0.015P、0.027S、0.95Cr)50 t电弧炉-LF-VD的生产过程为对象,利用热力学计算软件FactSage,研究CaO-SiO₂-Al₂O₃-MgO精炼渣系中不同成分比例对其熔点的影响,找出最佳的比例使夹杂物控制在低熔点区域,以便于去除。结果表明,(CaO)/(SiO₂) ≤1时,低熔点区域占总相图面积的百分比较大;当CaO含量为30%时,低熔点区域占总相图面积的百分比达到所有的最大值,为53.2%;4组元最佳配比为(%)30CaO-30SiO₂-25Al₂O₃-15MgO。