鹽素法に依る鋼中の非金屬介在物の定量法に就て(第一報)

Abstract

In the present experiment to determine non-metallic inclusions in carbon steels tne author tested some samples by means of the chlorine method adopted by Roland Wasmuht or E.W. Colbeck. However, in this method it was found that since the residues had been washed only with hot water after chlorination, exceedingly large amount of residues contaminated by the ferric hydroxide and silica gel were obtained, which had been produced by the hydrolysis of ferric and silicic chlorides remaining on boat; and that the total oxygen content calculated from the value of these oxides was three or five times greater than that obtained by the vacuum fusion method Accordingly, in order to eliminate these contaminating substances the residues were washed in the following order: -first with hot water, then by turns with hot 5% hydrochloric acid, hot water, hot 5% sodium carbonate solution, hot water, hot 5% hydroch oric acid, and finally with hot water. The chlorine method with the aforementionel improved washing procedure was applied to a number of killed steels, and the total oxygen content was found to agree precisely with the residues obtained by the vacuum fusion method.In the case of killed steels in which the ferrous and manganous oxides content were relatively low, non-metallic inclusions could be determined easily by the present method. However, steels with high content of these oxides were liable to be attacked, to some extent, by washing with the 5% hydrochloric acid washing. Therefore, the author extracted the residues after chlorination in the 5% sodium citrate solution (pH 7) to prevent ferric chloride from hydrolysis, then filtered and washed the residues with the 5% sodium carbonate solution to exclude the silica gel. In this procedure the total oxygen obtained by the chlorine method and the vacuum fusion method were in good agreement even in steels containing high percent inclusions of ferrous or manganous oxide.