Solidification Lab

THREE-DIMENSIONAL FINITE-ELEMENT SIMULATIONS OF FRECKLING IN ALLOY SOLIDIFICATION

by Jianzheng Guo and C. Beckermann, University of Iowa

The main objective of this research is to predict the nature and occurance of freckle defects in alloy solidification. Images of actual freckles from directionally solidified superalloy castings are contained in the following thumbnails (photos courtesy of A.F. Giamei, UTRC):

ingot  blade  freckle

The following images are the color figures for a paper on the grid effect in simulating freckling: Guo, J., and Beckermann, C., “Three-Dimensional Simulation of Freckle Formation during Binary Alloy Solidification: Effect of Mesh Spacing,” Numerical Heat Transfer, Part A, Vol. 44, pp. 559-576, 2003.

               

The following images are for some ProCast simulations for a 10mmx10mmx30mm domain:

  • animated fraction of solid evolution with cut off below 0.95
  • animated fraction of solid evolution with cut off above 0.1
  • final concentration
  • final concentration with cut off 10.5 ( initial concentration is 10%)
  • liquid concentration evolution animation

    • The following images and movies are from older three-dimensional simulations performed using a finite element program. They show liquid concentrations, liquid fractions, and velocities during solidification. The domain is cooled from below at a constant rate, and a certain temperature gradient is imposed between the top and bottom walls.

    freckle  freckle  freckle

    CLICK HERE FOR MOVIES (AVI Format):

  • 3-D view of liquid concentration
  • 3-D cut view of liquid concentration
  • 2-D cut view of liquid concentration
  • 2-D cut view of liquid concentration (stationary)
  • 2-D cut view of solid concentration
  • 2-D cut view of solid concentration (stationary)
  • 2-D cut view of liquid fraction
  • 2-D cut view of liquid fraction (stationary)

    • ... more on freckling in directional solidification

    Relevant Publications:

    Guo, J., and Beckermann, C., “Three-Dimensional Simulation of Freckle Formation during Binary Alloy Solidification: Effect of Mesh Spacing,” Numerical Heat Transfer, Part A, Vol. 44, pp. 559-576, 2003.

    Ramirez, J.C., and Beckermann, C., “Evaluation of a Rayleigh-Number-Based Freckle Criterion for Pb-Sn Alloys and Ni-Base Superalloys,” Metall. Mater. Trans. A, Vol. 34A, pp. 1525-1536, 2003.

    Beckermann, C., Gu, J.P., and Boettinger, W.J., "Development of a Freckle Predictor via Rayleigh Number Method for Single-Crystal Nickel-Base Superalloys," Met. and Mat. Transactions A, Vol. 31A, 2000, pp. 2545-2557.

    Schneider, M.C., Gu, J.P., Beckermann, C., Boettinger, W.J., and Kattner, U.R., "Modeling of Micro- and Macrosegregation and Freckle Formation in Single-Crystal Nickel-Base Superalloy Directional Solidification," Metall. and Mater. Transactions A, Vol. 28A, 1997, pp. 1517-1531.

    Gu, J.P., Beckermann, C., and Giamei, A.F., "Motion and Remelting of Dendrite Fragments during Directional Solidification of a Nickel-Base Superalloy," Metall. and Mater. Transactions A, Vol. 28A, 1997, pp. 1533-1542.