Quantitative Characterization of Graphite Morphology in Cast Iron from 3D Perspective

Abstract

Compared with 2D microstructure characterization, quantitative characterization of graphite morphology from 3D perspective can make it more possible to predict and improve properties of cast iron with relatively high accuracy. In the present study, based on 2D metallographic photos, X-ray tomography was utilized to investigate 3D morphology of graphite clusters in different cast iron and 3D quantitative characterization of graphite morphology was carried out by Avizo software. The results show that basically all nodular graphite in ductile iron are isolated and almost all graphite phase is interconnected in gray iron. The interconnectivity of compacted graphite iron is closely related with vermicularity. The flake-shaped graphite in gray iron is different with coral-shaped graphite in compacted graphite iron from 3D perspective. The quantity proportion of graphite clusters smaller than 10000μm3 is as high as 99.7% and 97.1% respectively in gray iron and compacted graphite iron with 91.3% vermicularity. The volume of graphite clusters larger than 100000μm3 basically accounts for most of graphite volume and the proportion is over 95% in gray iron and compacted graphite iron with high vermicularity. The difference of graphite volume distribution among different cast iron is mainly concentrated in the volume range from 10000 to 100000μm3.