Stable eutectoid transformation in nodular cast iron: modeling and validation

Abstract

This paper presents a new microstructural model of the stable eutectoid transformation in aspheroidal cast iron. The model takes into account the nucleation and growth of ferrite grainsand the growth of graphite spheroids. Different laws are assumed for the growth of both phasesduring and below the intercritical stable eutectoid. At a microstructural level, the initialconditions for the phase transformations are obtained from the microstructural simulation ofsolidification of the material, which considers the divorced eutectic and the subsequent growthof graphite spheroids up to the initiation of the stable eutectoid transformation. Thetemperature field is obtained by solving the energy equation by means of finite elements. Themicrostructural (phase change) and macrostructural (energy balance) models are coupled by asequential multiscale procedure. Experimental validation of the model is achieved bycomparison with measured values of fractions and radius of 2D view of ferrite grains.Agreement with such experiments indicates that the present model is capable of predictingferrite phase fraction and grain size with reasonable accuracy.