Modelling of Change in Density of Nodular Cast Iron During Solidification Using Cellular Automaton / Modelowanie Zmian Gęstości Żeliwa Sferoidalnego Podczas Krystalizacji Za Pomocą Automatu Komórkowego

Abstract

Density change occurring in ductile iron castings is a phenomenon far more complicated than in other casting alloys. Initially, graphite nodules grow directly from liquid phase. That is the reason for decrease in alloy density and casting expansion. Decaying carbon concentration in liquid phase adjacent to graphite nodules favours growth of austenite, which covers them isolating from the liquid. In order for graphite to grow further diffusion of carbon through thickening solid solution layer is needed. At this time expansion fades and shrinkage begins. Industrial experience shows that whether or not shrinkage defects in ductile iron castings will occur depends on wall thickness.

Keywords

• Nodular Iron
• Shrinkage
• Expansion
• CALPHAD
• Solidification modelling