An integrated approach for the characterization of the solidification structure of free graphite cast irons

Abstract

Over the years, the majority of the studies that addressed the study of the solidification of free graphite cast irons have focused primarily on explaining the influence of graphite morphology on the solidification mechanism, but instead, have dedicated much less attention to the influence of the metallic phase that grows together with graphite, which is the austenite. However, the combined use of the direct autempering after solidification technique and color etching makes it possible today to extend the study of the solidification of these materials by considering the growth of the austenite. The objective of the present study is to demonstrate how these two techniques can be exploited to understand the solidification macro and microstructure and the microshrinkage cavities formation in free graphite cast irons. The results show that these techniques find potential application in studies aimed at developing procedures to refine both the macroscopic and microscopic solidification structures, such as those investigating the use of inoculants to refine the austenitic grain structure, and its consequences on the microsegregation pattern, the eutectic solidification and the tendency to form microshrinkage.