抄録
We examined the formation mechanism of chunky graphite generated in heavy section spheroidal graphite cast iron. Chunky graphite is generated according to Ce contents. Moreover, it is generated mainly at the eutectic cell boundary, suggesting chunky graphite is generated due to the concentration of Ce with the progress of eutectic solidification. In this study, the solidification conditions of heavy casting were reproduced by maintaining a small quantity of molten metal at the eutectic temperature for a long time. Next, the electronic diffraction image and microstructure of various graphites were examined by TEM. As a result, chunky graphite was found to generate according to the eutectic solidification time and increase in the Ce content. It was also confirmed that chunky graphite was formed by X=1-exp (-b⋅tn) and generated by the growth of graphite with sufficient spherodizing ability in the direction where the basal plane expands predominantly.
