Abstract
It is essential for the manufacturing of nodular graphite cast iron that the properties of molten iron before magnesium treatment should be made constant, that is, constant degrees of desulfurization and deoxidation of molten iron, and the minimum magnesium amount should be employed. Though the properties of molten irons of cupola melting are changeable in the begining, intermediate and finishing periods of tapping, respectively, those in the batch system as in an electric furnace can be made constant by the reducing slag refining under a certain formula. On the other hand, the use of cerium together with magnesium enables not only to decrease the amount of magnesium but also to facilitate easy the selection of raw iron materials. From the above standpoint, the authors studied on an industrial scale a manufacturing method of nodular graphite cast iron, which uses the addition of magnesium and cerium to the molten irons desulfurized and deoxidized by the reducing melting in the Heroult electric furnace. Ca-Si-Mg and R-Ca-Si alloys, were used as graphite nodularizing alloys, and the most preferable conditions for theier application were made clear.
