Macrosegregation has been received high attention in the solidification modeling studies. In the present work, a numerical model was developed to predict the macrosegregation during the DC Casting of an Al-4.5 wt%Cu billet. The mathematical model developed in this study consists of mass, momentum, energy and species conservation equations for a two-phase mixture of liquid and solid in axisymmetric coordinates. The solution methodology is based on a standard Finite Volume Method. A new scheme called Semi-Implicit Method for Thermodynamically-Linked Equations (SIMTLE) was employed to link energy and species equations with phase diagram of the alloying system. The model was tested by experimental data extracted from an industrial scale DC caster and a relatively good agreement was obtained. It was concluded that a proper macrosegregation model needs two key features: a precise flow description in the two-phase regions and a capable efficient numerical scheme.

During the solidification of binary metal alloys, chemical heterogeneities at product scale over a long distance range (1cm-1m) develop and this has detrimental effect on the resulting mechanical properties of cast products. Macrosegregation is of great concern to alloy manufacturers and end users as this problem persist. In this study, the use of process parameters namely casting speed and runner angle to reduce Macro-Segregation in aluminum-copper binary alloy solidification is reported. The results from optical microscope, scanning electron microscope and energy dispersive spectrometry show that these parameters significantly influenced the development, size and volume of macrosegregation. The combination of parameters namely the pouring height between 96 mm/s, 100mm/s, and runner angles between 1200, 1500 produced less segregations with improved mechanical properties within standard specification. The modulus of elasticity (6800 MPa), tensile strength (110 MPa) and 2. 5 % elongation obtained in this study are within standard 7100 MPa, (88-124 MPa) and (1-25 %) respectively for this class of alloy.

In this paper, a macroscopic mathematical model is developed for simulation of transport phenomena during ternary alloy solidification processes, taking into account non-equilibrium effects due to solutal undercooling. The model is based on a fixed-grid, enthalpy-based, control volume approach. Microscopic features pertaining to non-eFquilibrium effects on account of solutal undercooling are incorporated through a novel formulation of a modified partition coefficient. The effective partition coefficient is numerically modeled by means of macroscopic parameters related to the solidifying domain. Numerical simulations are performed for ternary steel alloy by employing the present model and the resulting convection and macrosegregation patterns are analyzed. It is observed that the consideration of non-equilibrium solidification in the present mathematical approach is able to capture the thermo-solutal convection and leads to prediction of accurate value of macrosegregation. The results from the present model matches well with the experimental observations published in the literature.

In this paper, we present the relative problem of heat and mass transfer to adopt a means of imposing an electromagnetic field to improve solutal segregation (macrosegregation) during liquid metal solidification. A well-validated, quasi-two-dimensional solidifying experimental benchmark was introduced, which allowed us to observe the temperature field evolution and to provide the evident clues of phase transformation. We also observed naturally formed solutal segregations in the post-mortem sample. The idea of imposing a modulated magnetic field while optimizing modulation frequency and having a cable to suppress solutal segregation was confirmed by multiscale numerical modeling. Magnetohydrodynamics, flow driven by a modulated traveling magnetic field, was experimentally studied. Furthermore, a more practical cylindrical shape of liquid metal bulk driven by a permanent helical magnetic field has been achieved. The spatial flow behaviors suggested an appropriate magnetic field with optimized electromagnetic parameters for obtaining high-quality, low-defect casting products.