443超纯铁素体不锈钢冶炼过程氧含量和夹杂物分析

Analysis of the oxygen content and inclusions in 443 ultra-pure ferritic stainless steel

在443超纯铁素体不锈钢冶炼过程的AOD结束、VOD结束、LF钙处理后、LF钛、铌合金后及连铸浇铸中期分别取钢样,分析了全氧含量和夹杂物的类型及形貌特征。采用共存理论对冶炼过程的平衡氧含量进行了计算。试验结果表明:全氧含量和平衡氧含量的变化规律是一致的,随着冶炼过程进行,全氧含量和全氧平衡氧含量整体是不断降低的。夹杂物类型:AOD主要为CaO-SiO_(2)-Al_(2)O_(3)-MgO和Al_(2)O_(3);VOD主要为Al_(2)O_(3)和CaO-Al_(2)O_(3)-MgO-SiO_(2);LF钙处理后,主要为CaO-Al_(2)O_(3)-MgO-SiO_(2);连铸中间包中夹杂物类型和LF钛、铌合金化后的夹杂物类型是一致的,都为球形的CaO-Al_(2)O_(3)-MgO-TiO_(2)夹杂物。根据夹杂物类型提出了夹杂物的演变过程。

Samples taken from the end of AOD, the end of the VOD, LF after calcium treatment, LF alloying by Nb-Ti and tundish of the AOD-VOD-LF-tundish process during 443 ultra pure ferritic stainless steel were investigated to analyze the total oxygen and to characterize the inclusions type and morphology. The results show that the variation law for total oxygen is in good agreement with the equilibrium oxygen content. The total oxygen content and the equilibrium oxygen content decrease throughout the process. The types of inclusions change at different stages. The inclusion in AOD are mainly CaO-SiO_(2)-Al_(2)O_(3)-MgO and Al_(2)O_(3). The inclusions in VOD are mainly Al_(2)O_(3) and CaO-Al_(2)O_(3)-MgO-SiO_(2).The inclusions type are mainly CaO-Al_(2)O_(3)-MgO-SiO_(2) after calcium treatment in LF. The inclusions in tundish are mainly CaO-Al_(2)O_(3)-MgO-TiO_(2),while in LF after alloying by Nb-Ti. Evolution process for the inclusions in the 443 stainless steel is proposed based on the inclusions type.