Prediction of Chill Formation on Solidification of Multicomponent Cast Irons

Abstract

  Availability of the computer simulation based on the nucleation and growth models have been examined by comparing the results of simulation with those obtained by chill test of the Fe-C-Ni-Si-Cr multicomponent cast iron using a wedge-shape mold. A linear growth model for ledeburite combined with the radial growth model for gray eutectic was introduced and the prediction showed a satisfactory agreement with the observed distribution of chill fraction and chill depth. The graphitizing ability of silicon was comparable with the anti-graphitizing effect of chromium on relatively slow cooling, while faster cooling enhanced the graphitizing ability of silicon. It was demonstrated from the results of simulation that silicon equivalent of chromium, given by SE^∗ = (%Si) - (2/3) (%Cr) as a chilling index, showed a good correlation with logarithmic chill depth and logarithmic critical cooling rate for chill formation.