Abstract
A three-phase equiaxed solidification model where macroscale heat transfer and fluid flow are coupled with microscale nucleation and dendrite growth, is applied to the simulation of the macrosegregation in binary alloy solidification subjected to the electromagnetic stirring. The investigated experimental solidification case is conducted in a cavity which has a good control of the thermal boundary conditions. The proposed model uses a double time step scheme to accelerate the solution. Electromagnetic force is introduced as a source term into momentum equation in analytical form. To account for the friction from the side walls, a 2D½ flow model is applied to a three-dimensional experimental configuration. A comparison between the results of simulation and experimental ones is made.
Highlights
Macrosegregation defects often appear in ingot especially during a long-time solidification
The two-dimensional simulation of the experiment is still possible if an additional source term is introduced into the momentum equations to take into account the frictions from the large lateral walls which are absent in two-dimensional problem statement [30]
In the present simulation this term was implemented in the momentum equation for the liquid phase as well as the analytical expression for the Lorentz force
Summary
Macrosegregation defects often appear in ingot especially during a long-time solidification. These defects cannot be removed by the subsequent heat treatment or rolling process, and will affect the product properties. It was shown that using the electromagnetic stirring during solidification, a larger equiaxed grain zone and finer grain size can be obtained and macrosegregation can be reduced [4]. Sometimes heavier macrosegregation will be generated by the strengthened convection if parameters of electromagnetic stirring (EMS) are not appropriately chosen [3]. It is of high significance to have deep understanding of the mechanism how EMS affects the solute distribution during solidification that can be obtained through dedicated experiment and numerical modelling
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