次世代革新的鉄鋼材料開発のためのスピネル系介在物の生成・変質メカニズムの解明

本研究旨在阐明形成镁铝尖晶石和CaO-Al_2O_3类包裹体的镁、钙来源。为了形成MA尖晶石型夹杂物，研究了镁质耐火材料和含镁炉渣中镁的溶解行为。这里，关于镁基耐火材料，既使用了镁铬耐火材料，也使用了镁碳质耐火材料。针对CaO-Al_2O_3夹杂物的形成，研究了含CaO渣中钙的溶解行为。钢中铝还原不同成分炉渣中的氧化镁和氧化钙，使镁和钙溶于钢中。在纯镁渣实验中，当铝含量为0.25%时，形成富镁夹杂物，而当铝含量为2.5%时，尖晶石夹杂物中的镁含量增加到饱和状态。在实际处理过程中，Al_2O_3夹杂物转变为镁铝尖晶石夹杂物和少量CaO-Al_2O_3夹杂物。因此，在工业生产条件下，渣-钢反应不会形成CaO-Al_2O_3夹杂物。由此发现，CaO-Al_2O_3夹杂物形成的Ca主要来源于添加的合金，特别是Fe-Si。根据这些结果，我们发现在炼钢的精炼过程中，夹杂物只是通过Al_2O_3向尖晶石转变。为了防止CaO-Al_2O_3夹杂物的形成，应严格控制添加合金中的杂质。

The purpose of present study is to clarify the source of Mg and Ca for the formation of MgOAl2O3 (MA) spinel and CaO-Al2O3 type inclusions. For the formation of MA spinel type inclusion, the dissolution behavior of Mg from both MgO-based refractory and MgO-containing slag were studied. Here, about the MgO-based refractory, both the MgO-Cr2O3 refractory and MgO-C refractory were used. For the formation of CaO-Al2O3 type inclusion, the dissolution behavior of Ca from CaO-containing slag was studied. Both MgO and CaO in slag of different compositions were reduced by Al in steel, and Mg and Ca were dissolved into the steel. In the experiments using slag only saturated with MgO, when the Al content was 0.25%, the MgO-rich inclusion formed, while when the Al content was 2.5%, the MgO content of spinel inclusions increased to saturation.In order to confirm the above conclusions, an industrial experiment was conducted. During the actual LF treatment, the Al2O3 inclusion transformed to MgOAl2O3 spinel inclusion and few CaO-Al2O3 inclusion. Therefore, By the slag-steel reaction, CaO-Al2O3 inclusion could not form under the condition of industrial operation. Then, we found that the Ca for the formation of CaO-Al2O3 inclusion was from the added alloy, especially Fe-Si.Based on these results, we found that during the refining process of steelmaking, the inclusion only transformed through the routine of Al2O3 to MgOAl2O3 spinel. In order to hinder the formation of CaOAl2O3 inclusion, the impurity in the added alloy should be strictly controlled.