Abstract: The effect of magnesium on modification of non-metallic inclusions in steel SPHC (0. 065% C, 0. 025 % Al) is analyzed by thermodynamic calculation, and combined with commercial test by using an 80 t top and bottom combined blown converter flow sheet, the mechanism for influence of magnesium on inclusions in steel SPHC is studied. Thermodynamic calculation results prove that as[Al]²/a_[Mg]³≤7. 69 x 10¹⁰, the inclusion MgO • Al₂O₃ alone forms in steel ； Commercial test with feeding 0. 875 kg/t magnesium wire in steel SPHC shows that the inclusions are tine by magnesium treatment i. e. the round cluster Al₂O₃ is modified to fine inclusion MgO • Al₂O₃ while the inclusion MnS is also modified, the amount of inclusions in steel decreases and the cleanliness of steel in advanced.

Key words: Magnesium Treatment, Steel SPHC, Thermodynamic Calculation, Al₂O₃, MgO?Al₂O₃

摘要： 运用热力学计算分析了镁对SPHC钢(0.065%C、0.025%Al)中夹杂物的作用,并结合80 t顶底复吹转炉流程工业试验,研究镁对SPHC钢中夹杂物的影响机理。热力学计算结果证明,当[Al]²/a_[Mg]³≤7.69×10¹⁰,钢中就会生成单独的MgO·Al₂O₃;对SPHC钢进行喂0.875 kg/t镁线的工业试验结果表明,镁处理可细化夹杂,使团簇状Al₂O₃变为细小的MgO·Al₂O₃夹杂,MnS夹杂也得到了变性,夹杂物数量减少,提高了钢液的纯净度。

关键词: 镁处理, SPHC钢, 热力学计算, Al₂O₃, MgO?Al₂O₃