Abstract
The investigation was performed for purpose of determination of the effect of silicon and manganese on the casting structure of white iron.
The results obtained are listed as follows:
1) The carbide in iron-carbon-silicon alloy containing silicon more than a critical value consists of cementite and a constituent containing silico-carbide. This critical value of silicon content in order to produce the latter constituent decreases with decreasing size of castings. The latter constituent becomes yellow and cementite becomes brown when the polished surface of specimens are heat-tinted.
2) The yellow colored constituent of carbide is located around cementite.
3) The silicon content in the central part of pearite (or matrix) becomes lower than that in the circumference. The heterogeneity of silicon distribution seems to be promoted by rapid solidification of castings.
4) The inoculating treatment caused no appreciable change on the silicon distribution.
5) The number of etching nodules which appear by means of electrolytic etching in the Uhlig electrolyte increases with increasing silicon content or with decreasing size of castings.
6) The number of etching nodules increases with increasing manganese content and becomes maximum at 0.3-0.4% manganese and then decreases.
7) Manganese in white iron has an inclination to produce finer ledeburite and to lower the silicon content required to produce the yellow colored constituent.
8) The more numerous number of etching nodules results, the beter annealability of white iron.
