A comprehensive stochastic model for simulating grain structure formation and evolution during solidification processes is developed, based on a finite differential method (FDM) for macroscopic heat flow calculation and a cellular automaton method (CA) for microscopic modelling of nucleation, growth, solute redistribution and solute diffusion. Formation of peritectic phases in the last solidified liquid regions is considered. The growth rates of peritectic phases are calculated by the peritectic growth kinetics model. The solidification contraction is also taken into account. The calculated results are compared with those obtained experimentally. (c) 2005 Springer Science + Business Media, Inc.