Numerical simulation of a solidifying Pb-Sn alloy: The effects of cooling rate on thermosolutal convection and macrosegregation

Numerical simulations of a binary metal alloy (Pb-Sn) undergoing solidification phase change are performed using a continuum model for conservation of total mass, momentum, energy, and species. The system is contained in an axisymmetric, annular mold which is cooled along its outer vertical wall. Results show that thermosolutal convection in the melt and mushy zones is strongly coupled and that macrosegregation is reduced with increased cooling rate. For low cooling rates, solutally induced convection in the mushy zone favors the development of channels, which subsequently spawn macrosegregation in the form of A-segregates. With increasing solidification rate, however, thermosolutal interactions in the melt contribute to reducing the formation of channels and A-segregates.

[1]  Merton C. Flemings,et al.  Macrosegregation in a multicomponent low alloy steel , 1979 .

[2]  F. Incropera,et al.  Fundamentals of Heat Transfer , 1981 .

[3]  A. Hellawell,et al.  Channel formation in Pb-Sn, Pb-Sb, and Pb-Sn-Sb alloy ingots and comparison with the system NH4CI-H2O , 1988 .

[4]  C. J. Smithells,et al.  Smithells metals reference book , 1949 .

[5]  Frank P. Incropera,et al.  A continuum model for momentum, heat and species transport in binary solid-liquid phase change systems. II: Application to solidification in a rectangular cavity , 1987 .

[6]  G T Polley,et al.  Heat transfer and fluid flow , 1976 .

[7]  Frank P. Incropera,et al.  The evolution of macrosegregation in statically cast binary ingots , 1987 .

[8]  F. Incropera,et al.  Numerical simulation of solidification in a horizontal cylindrical annulus charged with an aqueous salt solution , 1990 .

[9]  Charles Vives,et al.  Local velocity and mass transfer measurements in molten metals using an incorporated magnet probe , 1982 .

[10]  Frank P. Incropera,et al.  Solidification of an aqueous ammonium chloride solution in a rectangular cavity—I. Experimental study , 1989 .

[11]  Merton C. Flemings,et al.  Interdendritic fluid flow and macrosegregation; influence of gravity , 1970 .

[12]  V. Voller,et al.  The modelling of heat, mass and solute transport in solidification systems , 1989 .

[13]  Christoph Beckermann,et al.  Natural Convection of Liquid Metals in Vertical Cavities , 1988 .

[14]  S. Kou,et al.  Effect of fluid flow on macrosegregation in axi-symmetric ingots , 1981 .

[15]  J. Szekely,et al.  An experimental and analytical study of the solidification of a binary dendritic system , 1978 .

[16]  D. R. Poirier,et al.  Flow of interdendritic liquid and permeability in pb-20 Wt Pct Sn alloys , 1985 .

[17]  M. J. Stewart,et al.  Fluid flow through a solid-liquid dendritic interface , 1972 .

[18]  V. Voller,et al.  A fixed grid numerical modelling methodology for convection-diffusion mushy region phase-change problems , 1987 .

[19]  S. Patankar.  Numerical Heat Transfer and Fluid Flow , 2018, Lecture Notes in Mechanical Engineering.

[20]  S. Asai,et al.  Theoretical Analysis and Model Experiments on the Formation Mechanism of Channel-type Segregation , 1978 .

[21]  Frank P. Incropera,et al.  Solidification of an aqueous ammonium chloride solution in a rectangular cavity—II. Comparison of predicted and measured results , 1989 .

[22]  Frank P. Incropera,et al.  Numerical analysis of binary solid-liquid phase change using a continuum model , 1988 .

[23]  A. Hellawell,et al.  The mechanisms of formation and prevention of channel segregation during alloy solidification , 1984 .

[24]  C. Vivès,et al.  Effects of electromagnetic stirring during the controlled solidification of tin , 1986 .

[25]  W. M. Haynes.  CRC Handbook of Chemistry and Physics , 1990 .

[26]  F. Incropera,et al.  A continuum model for momentum, heat and species transport in binary solid-liquid phase change systems—I. Model formulation , 1987 .

[27]  A. F. Giamei,et al.  The origin of freckles in unidirectionally solidified castings , 1970, Metallurgical and Materials Transactions B.