Paper Title:
Prediction of the Formation of an Equiaxed Zone Ahead of a Columnar Front in Binary Alloy Castings: Indirect and Direct Methods
  Abstract

The as-cast properties of components with a columnar grain structure are very different from those with an equiaxed one. Under certain solidification conditions, zones of both structures can occur in an alloy casting; the boundary between the zones is the columnar-to-equiaxed transition (CET). A front-tracking model of dendritic solidification has been developed, which can predict the nucleation and growth of solid in undercooled liquid during a casting process. The growth process is described by dendrite tip kinetics, and is fully coupled to a fixed-grid control volume model of heat transfer during solidification. Using the front-tracking model, two methods for predicting the likelihood of an equiaxed zone forming ahead of a columnar front have been formulated, namely, an indirect method and a direct method. The indirect method is based on modelling the growth of the columnar front in the absence of equiaxed nucleation. The bulk liquid undercooling is monitored and an equiaxed indicator is calculated at each time step based on the extent of such undercooling at that time. The equiaxed indicator is a measure of the relative likelihood of an equiaxed zone forming. In the direct method nucleation and growth of individual equiaxed grains is treated ahead of the advancing columnar front. In this case, if impingement of neighbouring fronts is treated, the simulation to complete solidification will yield the macrostructure and the CET. In this paper, details of both methods of equiaxed prediction are presented. Results from the indirect method are compared to experimental results found in literature and agreement is found.

  Info
Periodical
Edited by
A Roósz, M. Rettenmayr and Z. Gácsi
Pages
325-330
DOI
10.4028/www.scientific.net/MSF.508.325
Citation
S. McFadden, D. J. Browne, J. Banaszek, "Prediction of the Formation of an Equiaxed Zone Ahead of a Columnar Front in Binary Alloy Castings: Indirect and Direct Methods ", Materials Science Forum, Vol. 508, pp. 325-330, 2006
Online since
March 2006
Export
Price
$32.00
Share

In order to see related information, you need to Login.

In order to see related information, you need to Login.

Authors: K. Zaïdat, T. Ouled-Khachroum, Nathalie Mangelinck-Noël, Guillaume Reinhart, M.D. Dupouy, R. Moreau
Abstract:The specific objective of the paper is to investigate the effect of fluid flow on the development of a dendritic microstructure and more...
221
Authors: H.J. Dai, H.B. Dong, H.V. Atkinson, Peter D. Lee
Abstract:A coupled cellular automaton-finite difference (CA-FD) model is used to simulate the detailed dendritic structure evolution of the...
129
Authors: Laszlo Könözsy, Anton Ishmurzin, Monika Grasser, Meng Huai Wu, Andreas Ludwig, Robert Tanzer, Wolfgang Schützenhöfer
Abstract:The present paper deals with the formation of macrosegregation in a benchmark ingot using (Fe-C-Cr) ternary alloy composition. The numerical...
349
Authors: Shaun McFadden, David J. Browne, Laszlo Sturz, Gerhard Zimmermann
Abstract:This paper studies the Columnar to Equiaxed Transition (CET) in an Al-7wt%Si binary alloy with and without Al-Ti-B grain refiner. A...
361
Authors: Laszlo Könözsy, Mihaela Stefan Kharicha, Sven Eck, Meng Huai Wu, Andreas Ludwig
Abstract:This paper deals with the validation of a volume averaged multiphase solidification model based on a benchmark experiment using NH4Cl-H2O as...
367