A Principle of Steel-refining through Multiple Phases

Abstract

　　　In order to utilize iron scraps as iron resource, removal of impurity elements is necessary. In current refining process, impurities are removed to molten slag by oxidation from molten iron. However, some elements, such as Cu, are difficult to be removed from molten iron by current ways due to their chemical stability. Therefore, new refining technique is required. Since Ag is nobler than Cu, oxidation removal of Cu from molten iron can be possible via Ag phase. In order to confirm the condition of multiple phase to coexist, experiments were carried out with Fe-2mass%Cu-6mass%C alloy under distributed temperature to study a principle of steel-refining through multiple phases. Dendrites of γFe(s) and C(s) precipitated in upper part of a sample at low temperature. γFe(s) with C(s) inside was stabilized in upper part of a sample against high density of Fe. Then, it was possible to keep the multiple phases of γFe(s), Fe-C(l) and Ag(l). A distribution of Cu concentration under distributed temperature was observed.