Flow Control during Solidification of AlSi-Alloys by Means of Tailored AC Magnetic Fields and the Impact on the Mechanical Properties

Abstract:

This paper presents an experimental study which in a first stage is focused on obtaining quantitative information about the isothermal flow field exposed to various magnetic field configurations. Melt stirring has been realized by utilizing a rotating magnetic field. In a second step directional solidification of AlSi7 alloys from a water-cooled copper chill was carried out to verifythe effect of a certain flow field on the solidification process and on the resulting mechanical properties. The solidified structure was reviewed in comparison to an unaffected solidified ingot. Measurements of the phase distribution, the grain size, the hardness and the tensile strength were realized. Our results demonstrate the potential of magnetic fields to control the grain size, the formation of segregation freckles and the mechanical properties. In particular, time–modulated rotating fields show their capability to homogenize both the grain size distribution and the corresponding mechanical properties.

• Periodical: Materials Science Forum (Volumes 790-791)
• Pages: 384-389
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.790-791.384
• Online since: May 2014
• Authors: Dirk Räbiger, Bernd Willers, Sven Eckert
• Keywords: AlSi Alloy, Mechanical Property, Time-Modulated Rotating Magnetic Field

References

[1] D. G. McCartney: Grain refining of aluminium and its alloys using inoculants, Int. Mater. Rev. 34 (1989) 247-260.

DOI: 10.1179/imr.1989.34.1.247

[2] R.K. Trivedi: Microstructure characteristics of rapidly solidified alloys, Mater. Sci. Eng. A 178 (1994) 129-135.

[3] M.C. Flemings: Behavior of metal alloys in the semisolid state, Metall. Trans. A 22 (1991) 957-981.

DOI: 10.1007/bf02661090

[4] G.J. Eskin: Ultrasound treatment of Light Alloy Melt: Gordon and Breach, Amsterdam, (1998).

[5] E.O. Hall: The Deformation and Ageing of Mild Steel, Proc. Phys. Soc. London 64B (1951) 747-753.

[6] J.C. Li and Y.T. Chou: The Role of Dislocations in the Flow Stress Grain Size Relationships, Met. Trans. 1 (1970) 1145-1159.

DOI: 10.1007/bf02900225

[7] T.M. Yue, H.U. Ha and N.J. Musson: Grain size effects on the mechanical properties of some squeeze cast light alloys, J. Mat. Sci. 30 (1995) 2277-2283.

DOI: 10.1007/bf01184573

[8] J. Waldman, H. Sulinski and H. Markus: The Effect of Ingot Processing Treatments on the Grain Size and Properties of AI Alloy 7075, Metall. Trans. 5 (1974) 573-584.

DOI: 10.1007/bf02644652

[9] T.E. Quested: Understanding mechanisms of grain refinement of aluminium alloys by inoculation, Mater. Sci. Techn. 20 (2004) 1357-1369.

DOI: 10.1179/026708304225022359

[10] B.S. Murty, S.A. Kori and M. Chakraborty: Grain refinement of aluminium and its alloys by heterogeneous nucleation and alloying, Int. Mat. Rev. 47(1) (2002) 3-29.

DOI: 10.1179/095066001225001049

[11] W.D. Griffiths and D.G. McCartney: The effect of electromagnetic stirring during solidification on the structure of A1-Si alloys, Mat. Sci. Eng. A 216 (1996) 47-60.

DOI: 10.1016/0921-5093(96)10392-0

[12] M. Medina, Y. Du Terrail, F. Durand and Y. Fautrelle: Channel Segregation during Solidification and the Effects of an Alternating Traveling Magnetic Field, Metall. Mater. Trans. B 35 (2004) 743-755.

DOI: 10.1007/s11663-004-0014-8

[13] P.A. Nikrityuk, K. Eckert and R. Grundmann: A numerical study of unidirectional solidification of a binary metal alloy under influence of a rotating magnetic field, Int. J. Heat Mass Transfer 49 (2006) 1501-1515.

DOI: 10.1016/j.ijheatmasstransfer.2005.08.035

[14] S. Kojima, T. Ohnishi, T. Mori, K. Shiwaku, I. Wakusagi and M. Ohgarni: Development of Megnetic-stirring System in Bloom-caster, Proc. of the 66th Steelmaking Conf., Atlanta, ISS-AIME, 1983, Warrendale: 127-131.

[15] S. Eckert, P. A. Nikrityuk, D. Räbiger, K. Eckert and G. Gerbeth: Efficient Melt Stirring Using Pulse Sequences of a Rotating Magnetic Field: Part I, Metall. Mater. Trans. B 38 (2007) 977-988.

DOI: 10.1007/s11663-007-9096-4

[16] B. Willers, S. Eckert, P.A. Nikrityuk, D. Räbiger, J. Dong, K. Eckert and G. Gerbeth: Efficient Melt Stirring Using Pulse Sequences of a Rotating Magnetic Field: Part II, Metall. Mater. Trans. B 39 (2008) 304-316.

DOI: 10.1007/s11663-008-9126-x

[17] Y. Takeda: Development of an ultrasound velocity profile monitor, Nucl. Eng. Design 126 (1991) 277-284.

[18] S. Franke, H. Lieske, A. Fischer, L. Büttner, J. Czarske, D. Räbiger, S. Eckert, Two-dimensional ultrasound Doppler velocimeter for flow mapping of unsteady liquid metal flows, Ultrasonics 53, Issue 3, (2013) 691-700.

DOI: 10.1016/j.ultras.2012.10.009