Density of Eulectic Cells in Castings of Gray Cast Iron-a Theoretical Model and Experimental Verification

摘要

It has been worked out analytical model of solidification, which enables to calculate cells density in casting based only on knowledge of material parameters of metal and mould. Model takes into account process of heterogeneous nucleation of cells on so-called substrates (nucleation sites), which size is of the Weibull distribution as well as heat flux in metal-mould (with small intensity of cooling) system. Mathematical expression were derived which describe the density of eutectic cells in casting as a function of material parameters of metal and mould. Experimental verifications of the presented model were carried out on grey cast iron as an example with flake graphite and with different nucleation tendency, castings with different plates thickness as well as thermal analyses were used. Cells density (N) was calculated based on measured cross-section planar cells density by means of stereological method. From experiment results that process of creation of eutectic cells during solidification of cast iron proceeds according to worked out model.