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

本研究的目的是阐明MgOAl2O3 （MA）尖晶石和CaO-Al2O3型包裹体形成的Mg和Ca的来源。为了形成MA尖晶石型包裹体，研究了镁基耐火材料和含镁渣中Mg的溶解行为。本文采用了MgO-Cr2O3耐火材料和MgO-C耐火材料。为了形成CaO-Al2O3型夹杂物，研究了Ca在含cao渣中的溶解行为。钢中的Al对不同成分渣中的MgO和CaO均有还原作用，Mg和Ca均溶于钢中。在只饱和MgO的渣中，当Al含量为0.25%时，形成了富MgO的包裹体，而当Al含量为2.5%时，尖晶石包裹体的MgO含量趋于饱和。为了验证上述结论，进行了工业实验。在实际LF处理过程中，Al2O3夹杂物转变为MgOAl2O3尖晶石夹杂物和少量CaO-Al2O3夹杂物。因此，在工业操作条件下，通过钢渣反应不能形成CaO-Al2O3夹杂物。然后，我们发现形成CaO-Al2O3夹杂的Ca主要来自于添加的合金，尤其是Fe-Si。结果表明，在炼钢精炼过程中，夹杂物仅通过Al2O3向MgOAl2O3尖晶石的常规转化。为了阻止CaOAl2O3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.