Prediction of solid state structure based on eutectic and eutectoid transformation parameters in spheroidal graphite irons

The aim of the present work is to predict experimentally the structural trend of liquid iron based on its solidification features and the subsequent solid state transition. Both transformation processes in SG iron samples are simultaneously studied by means of industrial thermal analysis techniques. Experimental parameters are established in both cases in order to quantify the main metallurgical facts and correlate them with the structural properties of different alloys used in real manufacturing processes. A computer aided program has been designed for the treatment of the cooling curves. A large number of experimental tests using different chemical compositions were made. After curves treatment, several studies have been conducted to correlate the thermal parameters obtained and the structural properties detected via metallographic inspections. The influence of the solidification parameters on carbon diffusion process and the resulting structures is discussed. A new structural model was developed in order to predict the ferrite content on the basis of thermal evolution of SG iron. Nucleation potential (inoculation grade), carbide formation tendency and solid state evolution of metal are evaluated and final structure distribution is accurately estimated.