Effect of an Oxy-Sulphide Inoculant Enhancer on Graphite Parameters in the Mould Inoculated Compacted Graphite Cast Iron

Abstract

In compacted/vermicular graphite cast iron production, inoculation is applied to limit the formation of carbides, but usually this treatment also promotes nodular graphite with improved nodularity. The main objective of the present paper is to examine the graphite phase characteristics in these irons, as affected by different in the mould inoculation variants, for resin sand mould castings. Graphite shape factors illustrate the loss of compactness of the graphite particles in the surface layer of the casting and its variation with cooling rate changes, especially with the circularity expression. In the surface layer, up to 0.5 mm from the cast surface, inoculation increased graphite nodularity, with the performance of the inoculant enhancer alloy [OS-IE] treated iron also promoting a high nodularity through the section of casting. A specific effect of inoculation with this alloy is the formation of a high number of small graphite nodules, which is accompanied by higher nodularity and the highest levels for the circularity and sphericity shape factors. Inoculation with the (Ca+OS-IE) dual addition led to the highest compacted/vermicular graphite formation sensitivity, with limited nodular graphite formation.