On the kinetics of the eutectic expansion in cast irons

In this study, a combined Thermal Analysis (TA) - Linear Displacement Analysis (LDA) device was specifically created to evaluate the kinetics of the eutectic expansion during solidification of lamellar graphite (LG), compacted graphite (CG) and spheroidal graphite (SG) irons with carbon equivalent ranging from 3.71-4.56%. The TA – LDA system allowed the concurrent observation of eutectic expansion and cooling curves. The liquid iron was poured into the seamless molds encased in a spherical steel jacket to minimize the mold-wall movement. The system was equipped with a thermal couple (type S) and a Linear Variable Differential Transformer (LVDT) to monitor the temperature change and displacement during solidification. It was found that the eutectic expansion increased with higher carbon equivalent. The SG iron exhibited significantly higher eutectic expansion than the LG and CG irons. The accumulative expansion plots were demonstrated in the work.