Si添加熱延鋼板の高圧水によるデスケーリング性に及ぼす鋼中Sの影響

抄録

Effect of S on red scale defect, which is often observed as abnormal red scale stripes within normal black scale matrix especially in hot-rolled Si-added steel sheets, has been studied by means of laboratory hot rolling test. It was found that the area of red scale defect on the sheet surface decreases with increasing the S content. This can be explained by the formation of the eutectic compound of FeO/FeS with the low melting point of 940°C between steel substrate and upper eutectic compound of FeO/Fe₂SiO₄ with the melting point of 1173°C, i.e., the descaling ability of the primary scale is largely improved by the existence of the liquid phase in the process. The cause of formation of only FeS without MnS at the scale/steel interface in spite of significantly high amount of 1.5%Mn, is also discussed on the basis of chemical equilibrium diagrams calculated by the thermodynamic database "MALT2".