抄録
Non-metallic inclusions in the quenched samples with the chemical composition of 5%W, 4%Mo, 3%Cr, 1.5%V and 0.6%S were examined by means of microphotography, electrolytic isolation, chemical and X-ray analysis and electron-probe microanalysis. Most of the non-metallic inclusions were the sulphide of MnS type, including an adequate amount of Cr and a small amount of V.
The form of these inclusions is granular or starlike. The colour of these sulphide is almost gray but sometimes includes black spots or white spots. The black spots in the gray sulphide contain a large amount of Al and the white ones seem to be MC type carbide. FeS type inclusions were detected by X-ray analysis. The chemical composition of sulphide isolated by the electrolytic method is approximately Mn:Cr:Fe:S=3:1:2:3 in addition a small amount of V.
