Effect of Magnesium and Rare Earth Contents on Graphite Morphology of Compacted Vermicular Graphite Cast Iron

Abstract

  In the production of CV graphite cast iron, CV treatment alloy with high rare earth content is used. It has been reported to work as a substrate for graphite crystallization in spheroidal graphite cast iron and flaky graphite cast iron. In this study, the effect on graphite morphology was investigated by changing the amount of Mg and rare earth added. In addition, the graphite morphology during the cooling process was also clarified. The nucleus of primary graphite was qualitatively analyzed by water cooling at the primary temperature. The chemical composition of graphite nuclei changed with the amount of Mg and rare earth addition. Furthermore, the graphite morphology changed depending on chemical composition. It was also found that the appropriate amount of rare earth should be added according to the amount of Mg in the CV treatment alloy.