Abstract
During casting of aluminium extrusion ingots the surface against the mould experiences a pull-in force that magnifies the air-gap during solidification close to the mould surface. This is a global phenomenon that results in early and large air-gap formations compared to the shape-casting situation. Due to the semi-solid surface created under such conditions, exudation through the surface may appear. In this study a coupled heat and fluid flow, stresses and deformation modelling tool are applied on the process. Results from the mechanical calculation are back-coupled to the thermal boundary conditions. The metallostatic head is the driving force for exudation through the dendritic network and the resulting fluid flow through this network is used to calculate a dynamic thickness of the exuded layer. Measurements from two different alloys, with rather small changes in composition, but with large variations on surface quality, are compared with the modelling results.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
E. E. Emley. Continuous casting of aluminium. International Metals Reviews, pages 75–115, June 1976. Review 206.
A. Mo. Mathematical modelling of surface segregation in aluminium DC casting caused by exudation. International Journal of Heat and Mass Transfer, 36(18):4335–1340, 1993.
E. Haug, A. Mo, and H. J. Thevik. Macrosegregation near a cast surface caused by exudation and solidification shrinkage. International Journal of Heat and Mass Transfer, 38(9):1553–1563, 1995.
A. Mo, T. Rusten, H. J. Thevik, B. R. Henriksen, and E. K. Jensen. Modelling of surface segregation development during DC casting of rolling slab ingots. In R. Huglen, editor, Light Metals, pages 667–674, Warrendale, PA, USA, 1997. TMS-AIME.
H. J. Thevik, A. Mo, and T. Rusten. A mathematical model for surface segregation in aluminium DC casting. Metallurgical and Materials Transactions 5,30B:135–142, 1999.
M. Mhamdi, A. Mo, D. Lindholm, and D. Mortensen. Mathematical modelling of surface segregation in DC casting of multicomponent aluminium alloys. In P. R. Sahm, P. N. Hansen, and J. G. Conley, editors, Modelling of casting, welding and advanced solidification processes — IX, pages 656–663. Shaker Verlag, 2000.
D. Mortensen, B.R. Henriksen, J. Hvistendahl, H.G. Fjær, “Modelling of mould toe-in during extrusion ingot DC-casting”, Light Metals 2007, TMS, Warrendale, PA, pp 715–720.
H. G. Fjær and A. Håkonsen, “The mechanism of pull-in during DC-casting of aluminium sheet ingots”, Light Metals 1997, TMS, Warrendale, PA, pp 683–690.
D. Mortensen, “A mathematical model of the heat and fluid flows in direct-chill casting of aluminium sheet ingots and billet”, Metallurgical and Materials Transactions, 30B, (1999) pp 119–133.
H.G. Fjær and A. Mo, “ALSPEN — A mathematical model for thermal stresses in DC casting of aluminium billets”, Metallurgical Transactions, 21B, (1990) ppl049–1061.
J. Grandfield etal., “Remelt ingot mold heat flow and deformation”, Light Metals 2006, TMS, Warrendale, PA, pp 869–876.
J. Ni and C. Beckermann, “A volume-averaged two-phase model for transport phenomena during solidification”, Metall. Trans. B, 1991, vol. 22B, pp.349–361.
M. M’Hamdi, A. Mo and H.G. Fjær, “TearSim: A two-phase model addressing hot tearing formation during aluminium direct chill casting”, Metall. Trans. A, 2006, vol.37A, pp.3069–3083.
O. Ludwig, Ph.D. Thesis, Institut National Polytechnique de Grenoble, Grenoble, Feb. 2004.
A.L. Dons et.al., Metall. Trans. A, 1999, vol.30A, pp.2135–2146.
W.M. van Haaften, “Constitutive behaviour and hot tearing during aluminium DC casting”, PhD-Thesis TUDelft, The Netherlands, 2002. ISBN 90-9015792-1
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2016 The Minerals, Metals & Materials Society
About this chapter
Cite this chapter
Mortensen, D., Henriksen, B.R., M’Hamdi, M., Fjær, H.G. (2016). Coupled modelling of air-gap formation and surface exudation during extrusion ingot DC-casting. In: Grandfield, J.F., Eskin, D.G. (eds) Essential Readings in Light Metals. Springer, Cham. https://doi.org/10.1007/978-3-319-48228-6_101
Download citation
DOI: https://doi.org/10.1007/978-3-319-48228-6_101
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-48576-8
Online ISBN: 978-3-319-48228-6
eBook Packages: Chemistry and Materials ScienceChemistry and Material Science (R0)