Vermicular and Chunky Graphite Nucleation during Chill Casting: Study on the Dynamics of Ductile Iron Recycling

This investigation provides alternative insight into the dynamic behavior of spheroidal graphite structures throughout the remelting process during ductile cast iron recycling. Specifically, this study systematically analyzed the impact of the remelting process on graphite nucleation. Two approaches are included in this research: thermal analysis and the copper-mold chill casting method. Based on these results, different graphite structures nucleate in cast iron in response to the remelting and recasting processes, which correlate with the melting temperature, the cooling method, and the fading effect. Furthermore, it is indicated that the dissolution rate of spheroidal graphite is relatively slower than lamellar graphite, substantiated by the detection of residual graphite nodules in the case of low melting temperature applied during the remelting process. In addition, the formation of vermicular and potentially chunky graphite structures can also be observed to a certain extent during this set of investigations, thus providing further insight into their relation to the ductile cast iron production process.