Prediction of the formation of an equiaxed zone ahead of a columnar front in binary alloy castings: Indirect and direct methods

Shaun Mc Fadden, David J. Browne, Jerzy Banaszek

Research output: Chapter in Book/Report/Conference proceedingConference contribution

8 Citations (Scopus)

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.

LanguageEnglish
Title of host publicationSolidification and Gravity IV - Proceedings of the 4th International Conference on Solidification and Gravity
Pages325-330
Number of pages6
DOIs
Publication statusPublished - 1 Dec 2006
Event4th International Conference on Solidification and Gravity - Miskolc-Lillafuered, Hungary
Duration: 6 Sep 20049 Sep 2004

Publication series

NameMaterials Science Forum
Volume508
ISSN (Print)0255-5476

Conference

Conference4th International Conference on Solidification and Gravity
CountryHungary
CityMiskolc-Lillafuered
Period6/09/049/09/04

Fingerprint

Binary alloys
binary alloys
Solidification
solidification
Undercooling
Nucleation
predictions
Casting
nucleation
supercooling
Crystal microstructure
Liquids
impingement
dendrites
liquids
Heat transfer
Kinetics
Castings
casts
heat transfer

Keywords

  • Binary alloy solidification
  • Columnar front
  • Columnar-to-equiaxed transition
  • Equiaxed predictor
  • Equiaxed zone
  • Front-tracking

Cite this

Mc Fadden, S., Browne, D. J., & Banaszek, J. (2006). Prediction of the formation of an equiaxed zone ahead of a columnar front in binary alloy castings: Indirect and direct methods. In Solidification and Gravity IV - Proceedings of the 4th International Conference on Solidification and Gravity (pp. 325-330). (Materials Science Forum; Vol. 508). https://doi.org/10.4028/www.scientific.net/MSF.508.325
Mc Fadden, Shaun ; Browne, David J. ; Banaszek, Jerzy. / Prediction of the formation of an equiaxed zone ahead of a columnar front in binary alloy castings : Indirect and direct methods. Solidification and Gravity IV - Proceedings of the 4th International Conference on Solidification and Gravity. 2006. pp. 325-330 (Materials Science Forum).
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Mc Fadden, S, Browne, DJ & Banaszek, J 2006, Prediction of the formation of an equiaxed zone ahead of a columnar front in binary alloy castings: Indirect and direct methods. in Solidification and Gravity IV - Proceedings of the 4th International Conference on Solidification and Gravity. Materials Science Forum, vol. 508, pp. 325-330, 4th International Conference on Solidification and Gravity, Miskolc-Lillafuered, Hungary, 6/09/04. https://doi.org/10.4028/www.scientific.net/MSF.508.325

Prediction of the formation of an equiaxed zone ahead of a columnar front in binary alloy castings : Indirect and direct methods. / Mc Fadden, Shaun; Browne, David J.; Banaszek, Jerzy.

Solidification and Gravity IV - Proceedings of the 4th International Conference on Solidification and Gravity. 2006. p. 325-330 (Materials Science Forum; Vol. 508).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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AB - 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.

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Mc Fadden S, Browne DJ, Banaszek J. Prediction of the formation of an equiaxed zone ahead of a columnar front in binary alloy castings: Indirect and direct methods. In Solidification and Gravity IV - Proceedings of the 4th International Conference on Solidification and Gravity. 2006. p. 325-330. (Materials Science Forum). https://doi.org/10.4028/www.scientific.net/MSF.508.325