Oxide inclusions in a Fe-Cr-Ni steel sample were classified in four types; they are those composed of mainly silicate glass, wollastonite and silicate glass, dendritic crystals and silicate glass, and the aggregate of fine crystals. Main constituent phases were analysed by X-ray microanalyser to presume the chemical composition of the inclusions. In addition, a correction method for estimating the actual size distribution of spherical inclusions from that of sectional radii of the inclusions on polished surface of steel was investigated. This method was applied to microscopic analysis of the inclusion of each type in the steel sample.
These analytical results are discussed with relation to the steelmaking conitions.