Successive steps of growth of compacted graphite in cast irons

Abstract

Holding during 8 hours a melt prepared for casting SGI leads to fading of the spheroidizing treatment and thus to growth of compacted graphite instead of spheroidal graphite. Such a melt was cast in thermal analysis cups at 25-30 minutes interval without inoculation. It solidified first in the stable system and more and more in the metastable system. Accordingly, recalescence first increased as more of compacted graphite solidified, but then decreased when more and more of the solidification occurred in the metastable system. Comparison of the results of the present study with those of a previous similar series showed a higher peak recalescence while the number of compacted graphite cells and the graphite fraction were the same within experimental scattering. Furthermore, as the amount of spheroidizers was similar in both series, there is no clear reason for this difference in recalescence, which should be investigated further.