Effects of Rare Earth Elements and Antimony on Morphology of Spheroidal Graphite in Heavy-Walled Ductile Cast Iron

Abstract

  It is well known that the mechanical properties of heavy-walled ductile cast iron decrease due to morphological changes of spheroidal graphite. The effects of RE and Sb contents on the morphological changes of graphite (especially the appearance of chunky graphite and exploded graphite) were studied using a test block which was solidified with the simulated time for heavy-walled ductile casting. The followings were confirmed in this study. (1) Exploded graphite appears when RE contents are above 0.02 mass % (2) Chunky graphite does not appear when the Sb/RE ratio is above 0.7. The cause of the chunky graphite appearance will be studied next.