Abstract: The metallurgical flowsheet for steel 18CrNiMo7-6 (/%: 0. 17C, 0. 57Mn, 0. 24Si, 0. 012P, 0. 003S, 1.70Cr, 1. 49Ni, 0. 28Mo) is 60t EAF-LF-VD-2.1t ingot. The variation of amount, size and ingredient of inclusions in steel after EAF aluminium pre-oxidation, LF aluminium shot and silicon-carbide mix deoxidant diffusion deoxidation (LF initial slag ingredient /%: 57 ~ 60CaO, 20. 5 ~ 22. 0Al₂O₃, 9. 9 ~ 11. 3SiO₂ , 8. 8 ~ 10. 6MgO, 0. 7 ~ 1. 1FeO, 0. 7 ~ 0.9MnO) , VD and soft blowing has been analyzed by sampling. Results show that during refining process the amount of  inclusions decreases by 16. 67% , the amount of >10μm inclusions decreases by 50% and the ≥30μm inclusions basically are removed from liquid ； during refining process the main formed-inclusions are magnesium-aluminium-calcium compound inclusions and CaS, MgS and MnS etc sulfide; the main inclusions in finished products are Mg-Al oxides and main sulfide is MgS with minor MnS and CaS etc sulfide. The further optimized steelmaking process is to control the formation of small and medium size inclusions.

摘要： 18CrNiMo7-6钢（/%:0.17C,0.57Mn,0.24Si,0.012P,0.003S,1.70Cr,1.49Ni,0.28Mo）的冶金流程为60t EAF-LF-VD-2.1t铸锭。取样分析了EAF铝锭预脱氧,LF铝粒和碳化硅混合脱氧剂扩散脱氧（LF初渣成分/%:57~60CaO,20.5~22.0Al₂O₃,9.9~11.3SiO₂,8.8~10.6MgO,0.7~1.1FeO,0.7~0.9MnO）,VD后和软吹后钢中夹杂物数量、尺寸和组成的变化。结果表明,精炼过程1~10μm夹杂物数量降低16.67%,>10μm夹杂物数量降低50%,≥30μm夹杂物基本去除;精炼过程中生成的夹杂主要为镁铝钙的复合夹杂物和CaS,MgS,MnS等硫化物;成品材中主要为Mg-Al的氧化物夹杂,硫化物以MgS为主,有少量MnS、CaS。应进一步优化冶炼工艺,控制中小型夹杂物的形成。

关键词: 18CrNiMo74齿轮钢, 60t LF-VD精炼, 非金属夹杂物演变, 分析