抄録
When steels centaining chromium are treated with chlorine gas at elevated temperature, anbydrous chromic chloride is formed, which is not wholly volatilized and insoluble in water. Hence the chlorine method in determination of non-metallic inclusions in steels containing chromium has not been applied hitherto. Wasmulit reported that the insoluble chloride is removed away by washing the residues with a warm diluted solution of stannous chloride. According to the present experiment, however, the anbydrous chromic chloride is not dissolved completely by such a procedure and it is necessary to use a fairly concentrated solution of chromous ions.
A satisfactory method, therefore, was proposed by the present writer; that is, the residue after chlorination is treated with a concentrated chromous chloride solution prepared by the following method. 5g K2Cr2O7 was dissolved in 100cc HCl (1:1), and reduced to chromic state with alcohol and then re uced to chromous state with 5g zinc in nitrogen atmosphere. Considerable amount of HCl used are consumed in arising KCl, CrCl2 and ZnCl2, and the resulting concentration of HCl is less than 5%, so that the non-metallic inclusions are not dissolved away.
The aforementioned modified chlorine method was applied to various engineering alloy steels containing chromium, such as 1% chromium steels, nickel-chromium steels, chromium-molybdenium steels, high carbon chromium steels, nitriding steels and stainless steels, and satisfactory results were obtained. The total oxygen content determined by the chlorine method well coincides with that of vacuum fusion method.
