|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Applications of Solidification Fundamentals
||3D Phase-field Simulations of Graphite Growth in Ductile Cast Iron Considering Interaction between Local Expansion and Microsegregation
||Janin Eiken, Bernd Böttger
|On-Site Speaker (Planned)
The solidification of multicomponent ductile cast iron (Fe-C-Si-Mn-Mg) was simulated on the microstructure scale using the Micress multi-phase-field model extended by a new solver which considers volumetric expansion. Thermodynamic and diffusion data were evaluated by online coupling to the Calphad database TCFE8. The simulations were performed in three dimensions to correctly handle the critical volume-to-length ratios. During initial solidification, dendritic austenite and graphite nodules grow as a divorced eutectic. Whenever a graphite nodule gets into direct contact with the austenite, it becomes rapidly encapsulated and isolated from the melt. The subsequent growth of this nodule is then controlled by interstitial diffusion of carbon through the austenitic shell. During this indirect eutectic transition, the volumetric expansion of the graphite causes a pushing of the enveloping austenitic shell, i.e. a local transport of Fe as well as solute atoms. This mechanism has been found to significantly affect growth kinetics and microsegregation.
||Planned: Supplemental Proceedings volume