Numerical modelling of solidification of thin walled hypereutectic ductile cast iron

Karl Martin Pedersen, Jesper Hattel, Niels Tiedje

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    Abstract

    Numerical simulation of solidification of ductile cast iron is normally based on a model where graphite nodules are surrounded by an austenite shell. The two phases are then growing as two concentric spheres governed by diffusion of carbon through the austenite shell. Experiments have however shown the presence of austenite dendrites even in hypereutectic castings. In thin-walled castings the presence of austenite dendrites is even more pronounced, which increases the risk of shrinkage porosities. This off-eutectic austenite is therefore an important part that should be taken into account during simulation of thin-walled ductile iron castings. Simulations have been performed with a 1-D numerical solidi¬fication model that includes the precipitation of non-eutectic austenite during the eutectic stage. Results from the simulations have been compared with experimental castings with wall thick¬nesses between 2.8 and 8 mm. The experiments have shown that the solidification of thin-walled castings is divided into two stages where the first stage is relatively small with little or no reca¬lescence and the second stage is the main stage with a larger recalescence. In the 8 mm plates the eutectic solidification had only one main stage. The simulations reveal that the first stage of solidification can be explained by precipitation of off-eutectic austenite
    Original languageEnglish
    Title of host publicationModeling of Casting, Welding and Advanced Solidification Processes XI
    Publication date2006
    Publication statusPublished - 2006
    Event11th International Concerence on Modeling of Casting, Welding and Advanced Solidification Processes XI - Nice, France
    Duration: 28 May 20062 Jun 2006
    Conference number: 11

    Conference

    Conference11th International Concerence on Modeling of Casting, Welding and Advanced Solidification Processes XI
    Number11
    CountryFrance
    CityNice
    Period28/05/200602/06/2006

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