Thermal Analysis and Graphitization Ability of Spheroidal Graphite Cast Iron Preconditioned by Al,Zr,Ca–FeSi

The increasing demand for pre-pouring melt quality evaluation by thermal analysis has led to some important breakthroughs in understanding the solidification of spheroidal graphite cast iron (SGI). The two important parameters which characterize the solidification cooling curve of SGI are temperature of eutectic undercooling (TEU) temperature of eutectic recalescence (TER). In this study, the response of preconditioning treatment (0.1% Al,Zr,Ca–FeSi) on TEU and TER was investigated in several samples from different heats. It was found that preconditioning increases both TEU and TER. The average eutectic graphitization ability after preconditioning was found to increase from 60 to 75. The average undercooling (∆T) and recalescence (∆Tr) in preconditioned samples were 12 °C and 2 °C, whereas in samples without preconditioning average ∆T and ∆Tr are 19 °C and 7 °C, respectively. Preconditioning improves graphitization ability thereby increasing the graphite nodule count. The actual nodule count of SG iron samples obtained by image analysis was found to be in agreement with that of nodule counts predicted by thermal analysis.