Effects of Cu and Sn Additions on Graphite Morphology of Compacted Vermicular Graphite Cast Iron

Abstract

  In CV graphite cast iron, the mechanical properties of the thick part tend to be low, making adaptation to large castings difficult. Low mechanical properties are caused by the coarsening of caterpillar graphite in the thick part and the ferrite matrix. It is therefore necessary to strengthen the matrix. In this study, the effects of varying the amounts of pearlite promoting elements, Cu and Sn, on graphite morphology and matrix structure were investigated. The graphite morphology changed from CV to spheroidal, and the matrix structure changed from ferrite to pearlite. In addition, the graphite morphology changed to spheroidal graphite as the cooling rate decreased. These results are considered to be due to the effect of Cu and Sn layers formed around the graphite.