THE STRENGTH OF THE COUPLING BETWEEN MACROSCOPIC HEAT-FLOW AND EQUIAXED GRAIN FORMATION IN CASTINGS

The strength of the coupling between heat flow and microstructure form ation during solidification depends on the kinetics of the microstruct ural phenomenon. Strong coupling makes it necessary to solve the equat ions governing heat flow and those governing microstructure formation simultaneously in order to predict the evolution of temperature field and the microstructure. If the coupling is weak, uncoupling the equati ons to some extent and simplifying the calculation procedure does not affect the predictions of the calculations. In this work the strength of the coupling in the case of equiaxed eutectic grain formation is in vestigated in order to see to what extent the governing equations can be uncoupled. It is found that the coupling is so strong that full cou pling of the equations is essential to get reliable results.