Abstract: The evolution behavior of total oxygen content and amount, size, ingredient and type of inclusions in steel during steelmaking process of stainless steel 304 by 160 t EAF-180 t AOD-LF-CC flowsheet has been studied by nitrogen oxygen analyzer, optical and scanning electron microscope. The AOD refining process main operation data are initial [C] 2.0% 〜3.0%, [Si] 0.2% 〜0.4%, end [C] 0.04% 〜0.06% , end AOD slag ingredient (/%)： 53.9CaO, 30. 1 SiO₂, 1. 34Al₂O₃, 5. 22MgO, 8. 74CaF₂, 0. 39Cr₂O₃, 0. 53TFe, 0. 62MnO, and end LF slag ingredient (/%)： 57.9CaO, 21.6SiO2, 1.70Al₂O₃, 6. 30MgO, 0. 03Cr₂O₃, 11.9CaF₂, 0. 26TFe, 0.31MnO. Results show that in AOD- LF-CC process the oxygen content in steel decreases gradually, the deoxidized ratio is up to 71. 0% and the oxygen content in casting slab is 25 x 10^-6 ； the amount of large inclusions decreases obviously in refining process, and there is no ≥20μm inclusion occurring in casting bloom ； during refining process the main inclusions in steel are low-melting silicate, and from end LF to cast slab the MgO and Al₂O₃ content in inclusions increase respectively by 12% and 17. 5% , due to temperature decreasing, in cast slab the residual Mg, Al continuously combined with 0 to precipitate MgO-Al₂O₃ Aspinel and residual Mg and Al reacting with low-melting siHcate to form high-melting silicate, therefore the inclusions in cast slab are mainly magnesium-aluminium spinel and high-melting silicate.

Key words: 160 t EAF- 180 t AOD- LF- CC Flowsheet, Stainless Steel 304, Inclusions, Oxygen Content, Silicate, Magnesium-Aluminium Spinel

摘要： 采用氧氮分析仪、扫描电镜、金相显微镜研究了160 t EAF-180 t AOD-LF-CC工艺生产304不锈钢的冶炼过程中全氧含量和夹杂物数量、尺寸、成分、类型等的衍变行为。AOD初始[C]2.0%3.0%,[Si]0.2%~0.4%,终点[C]0.04%~0.06%,AOD终渣为（/%）:53.9%CaO,30.1SiO₂,1.34Al₂O₃,5.22MgO,8.74CaF₂,0.39Cr₂O₃,0.53TFe,0.62MnO,LF终渣为（/%）:57.9CaO,21.6SiO₂,1.70Al₂O₃,6.30MgO,0.03Cr₂O₃,11.9CaF₂,0.26TFe,0.31 MnO。结果表明,AOD-LF-CC过程中氧含量逐渐降低,脱氧率达到71.0%,铸坯氧含量为25×10^-6;在精炼过程中大型夹杂物数量明显降低,铸坯中没有出现≥20μm的夹杂物;在精炼过程钢中夹杂物主要以低熔点的硅酸盐为主,从LF终点至铸坯夹杂物中MgO和Al₂O₃含量分别升高了12%和17.5%,因温度降低,铸坯中残余的Mg、Al和O不断结合析出MgO-Al₂O₃尖晶石,同时残余的Mg、Al与低熔点的硅酸盐夹杂物发生反应形成高熔点的硅酸盐,所以铸坯中夹杂物主要以镁铝尖晶石和高熔点硅酸盐为主。