钙铝酸盐夹杂物在RH真空过程的演变行为

Evolution Behavior of Calcium Aluminate Inclusions in RH Vacuum Process

针对LZ50车轴钢,通过对RH精炼过程连续取样,采用电子显微镜、全自动夹杂物分析系统研究夹杂物的形貌、尺寸及组成分析其演变规律。研究钙元素在真空过程中的损失规律,结果表明[Ca]含量的损失主要发生在RH真空处理前期,并且随着真空循环10 min左右后,钢中的[Ca]降低至降10×10-6左右,并在后期基本保持不变。利用FactSage软件绘制1600℃时的CaO-MgO-Al2 O3三元相图,其内部较高的MgO比例间接反映了耐火材料进入钢液参与反应,炉渣中MgO含量增加,也间接反应出耐火材料的侵蚀,进而含镁夹杂物上浮进入炉渣中。RH过程夹杂物的数量和所占面积整体上先增加后减少。RH精炼过程的夹杂物数量、尺寸分布以及成分演变规律进行研究,尤其对CaO-MgO-Al2O3类夹杂物的变化规律进行统计分析,旨在明确RH真空精炼过程夹杂物的变化规律,并用以指导生产。

For the LZ50 axle stell,through contionus sampling of the RH refining process,an electron microscope and an antomatic inclusion analysis system were used to study the shape,size and composifion of the inclusions and analyze the evolution and the loss rule of calcium in the vacuum process wass studied.The results show that the loss of[Ca]content mainly occurs in the early stage of RH vacuum treatment,and with the vacuum cycle of about 10 minutes,the steel[Ca]reduced to about 10×10-6,and remained basically unchanged in the later period.Using the Facestage software to draw the Cao-MgO-Al2O3 ternary phase diagram at 1600℃,the higher internal MgO ratio indirectly reflects the refractory material enterring the molten steel to participate in the reaction.The increase of MgO content in the slag also indirectly reflect the erosion of the refractory material and then the magnesium-containing inclusions float up into the slag.The number and area of inclusion in the RH process first increased and the decreased.Next,the number,size distribution and composition evolution of inclusions in RH refining process were studied.Especially,the variation of CaO-MgO-Al2O3 inclusions was statistically analyzed to clarify the variation of inclusions in RH vacuum refining process and used to guide production.