Modelling of microstructure and property distribution within industrial nodular graphite iron casting

A kinetic model that uses the internal state variable approach has been developed and implemented as a user-subroutine in a finite element model (FEM) program in order to relate the heat flow calculations to the micro-structure evolution within a complex shaped industrial nodular graphite iron casting. The model initially requires the input of the chemical composition and from there it is coupled with the heat flow calculations from which the evolution of the constituent phases are calculated utilising the constraint conditions imposed by the phase diagram and the kinetic equations. A further sophistication of the model involves the use of a separate set of response equations to relate the microstructure and the composition to the macro-mechanical properties, such as hardness, yield and tensile strength. In a calibrated form, the process model is capable of describing the microstructure evolution during primary and eutectic solidification as well as the subsequent solid-state transformations. IJCMR/368