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在1 873K,MgO坩埚内进行了VOD精炼渣与SUS444铁素体不锈钢之间的脱氧平衡试验,考察了精炼渣对不锈钢中T.O含量及夹杂物组成、数量和尺寸分布的影响。结果表明,脱氧终点钢中w(T.O)=0.006 3%~0.007 4%,提高精炼渣碱度,降低渣中Al2O3的活度,有利于降低钢中T.O含量。精炼渣碱度增加,试样中单位面积夹杂物的个数及夹杂物的平均面积分数都减小。降低渣中Al2O3含量,夹杂物平均粒径也降低。加入脱氧合金后,钢中夹杂物主要为Al2O3、MgO·Al2O3及含有少量SiO2、MnO的复合氧化物;钙处理后,钢中夹杂物主要为球形的MgO·Al2O3-CaO。随着精炼渣中a(MgO)/a(Al2O3)的增加,MgO·Al2O3夹杂物中xMgO/xAl2O3随之增加。根据试验,R=3.5、w(Al2O3)=10%、w(MgO)=10%、w(CaF2)=5%的精炼渣具有良好的精炼效果。
The deoxidation balance between VOD refining slag and SUS444 ferritic stainless steel was carried out in a 1873K MgO crucible. The effects of refining slag on the content of T.O. and the composition, quantity and size distribution of inclusions in stainless steel were investigated. The results show that w (T.O) = 0.006 3% ~ 0.007 4% in the final deoxidized steel increases the basicity of slag and reduces the activity of Al2O3 in the slag, which is beneficial to reduce the content of T.O. Refining slag alkalinity increases, the number of inclusions per unit area of the sample and the average area fraction of inclusions are reduced. Reduce the content of Al2O3 in the slag, the average inclusion size is also reduced. After adding deoxidized alloy, the inclusions in the steel are mainly Al2O3, MgO · Al2O3 and composite oxides containing a small amount of SiO2 and MnO. After calcium treatment, the inclusions in the steel are mainly spherical MgO · Al2O3-CaO. With the increase of a (MgO) / a (Al2O3) in the refining slag, the amount of xMgO / xAl2O3 in MgO · Al2O3 inclusions increases. According to the test, refined slag with R = 3.5, w (Al2O3) = 10%, w (MgO) = 10% and w (CaF2) = 5% has a good refining effect.