THEORY OF GRAPHITE NUCLEATION IN LAMELLAR GRAPHITE CAST IRON

摘要

The precise knowledge of the fundamentals of nucleation is the key to a reliable production process for the fabrication of high quality cast iron products. In most foundries the production process is optimized based on practical experience and not on precise theoretical knowledge. Our work focuses on the research of graphite nucleation in lamellar cast iron. The results of the microscopical investigations are showing for the first time centres of graphite lamella. They are present in the middle of the MnS-particles. The nucleation of graphite on MnS particles was confirmed by microstructure simulations. Studies on the influence of Mn and S on the grain microstructure show that the contents of both elements play an important role. By treating the melt with small contents of Mg, MnSMg particles could also be observed in the matrix as well as in the graphite centres.