Modeling of in-ladle direct thermal control rheocasting process

In-ladle direct thermal control (DTC) rheocasting, based on the microstructure control concept of Hitachi and process concept of thermomechanical treatment (TMT) presses, has been developed. It requires no processing equipment outside of the casting machine, no grain refinement procedure and no additional cycling time except for cooling down to the desired casting temperature. Process concept of in-ladle DTC rheocasting is simply based on the fact that there is slurry and mush transition in every molten metal and the transition occurs in the range of liquid fraction of 0.1–0.6, which could be controlled by controlling its shape and relative interfacial energy. This study is concerned about the possibility to obtain semisolid slurry during partial solidification only through thermal control, that is, by in-ladle DTC rheocasting. Modeling of heat transfer for in-ladle DTC rheocasting was carried out to investigate the effect of pouring temperature, ladle material, ladle geometry, ladle preheat and alloy composition by two-dimensional finite volume method. Actual experiments were also carried out to compare the results obtained by modeling.