低硫鋼でのMnS析出に及ぼす鋼中酸化物の影響

抄録

The behavior of MnS precipitation on oxide particles in low sulphur and low carbon steels was investigated to control the size and the distribution of MnS. The distribution of MnS became uniform by the complex deoxidation with Mn-Si-Zr, of which complex oxides dispersed finely. On the other hand, in the case of carbon deoxidation in vacuum melting, MnS precipitated less uniformly in interdendritic regions. The precipitation ratio of MnS on oxide particles was higher in the cases of Mn-Al, Mn-Si and Mn-Si-Zr deoxidations, but it depended on the oxide composition. Higher precipitation ratio was obtained in the composition range of MnO-SiO₂ where liquidus temperature is low and sulphide capacity is high. The small MnS embryo formed on the surface of the liquid oxide according to its solubility limit may act as a nucleus for the further growth of MnS due to diffusion after the solidification of steels.