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采用氧氮分析仪、扫描电镜、金相显微镜等分析手段,系统研究LF精炼渣系对304系不锈钢全氧质量分数wT[O]、夹杂物数量、尺寸及成分的影响。研究结果表明,当LF精炼渣碱度由1.5升高至2.6时,LF出站溶解氧质量分数w[O]由11.6×10~(-6)降低至4.8×10~(-6),铸坯wT[O]由47×10~(-6)降低至24×10~(-6),铸坯夹杂物总数量降低,但当量直径不大于10μm的夹杂物所占比率由77.7%增加至95.1%。热力学计算结果表明:在钢液中各元素达到平衡状态时,渣系碱度越高,低熔点夹杂物2MgO·2Al_2O_3·5SiO_2生成区域越小,MgO·Al_2O_3尖晶石类夹杂物生成区域越大,与生产试验结果一致。随着LF炉渣碱度升高,铸坯夹杂物成分中MgO和Al_2O_3的质量分数分别升高了14.4%和9.1%,当碱度不大于1.9时,铸坯中不会存在镁铝尖晶石。
Oxygen and nitrogen analyzer, scanning electron microscope, metallurgical microscope and other analytical tools were used to systematically study the influence of LF refining slag system on the oxygen content wT [O], the number of inclusions, size and composition of 304 stainless steel. The results show that when the basicity of LF refining slag increases from 1.5 to 2.6, the dissolved oxygen mass fraction w [O] at LF outbound decreases from 11.6 × 10 -6 to 4.8 × 10 -6, The wT [O] decreased from 47 × 10 ~ (-6) to 24 × 10 ~ (-6), the total amount of inclusions decreased, but the proportion of inclusions with equivalent diameter of 10μm increased from 77.7% 95.1%. The results of thermodynamic calculation show that the higher the slag basicity is, the smaller the formation area of 2MgO · 2Al 2 O 3 · 5SiO 2 inclusions with low melting point is and the larger the formation area of MgO · Al 2 O 3 spinel inclusions is , Consistent with the production test results. With the increase of basicity of LF slag, the mass fraction of MgO and Al_2O_3 in the inclusions of slab increased by 14.4% and 9.1% respectively. When the basicity is not more than 1.9, there is no Mg-Al spinel .