The effect of electromagnetic stirring during solidification on the structure of Al-Si alloys

Griffiths, W.D.; McCartney, D.G.

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

Cited by 136 publications

(47 citation statements)

References 17 publications

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“…The problem is old, and numerous attempts have already been made to solve at least a few issues. Papers have been published investigating the effect of flow on the growth of primary dendrite trunks, the evolution of side branches, the entrainment of solute in the mush [7], the effects of artificial flow induced by rotating or alternating magnetic fields on cast microstructures [8]. However, the understanding of fluid flow on the liquid-to-solid transformation is rather in its infancy and tremendous progress is expected from comparison of simulations with results provided by space experiments.…”

Section: Forest-likementioning

confidence: 99%

Materials solidification physics in space

Ratke¹,

Gandin²,

Mathiesen³

et al. 2008

Europhysics News

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International audienceOne of the major unresolved problems in solidification physics and its industrial counterpart, the foundry industry, reads simply: the effect of fluid flow on the microstructure of cast products. As "cast" is just another word for "forced flow" and casting of alloys is an art and engineering technology of a few thousand years old, it might appear peculiar that the interplay between an advancing solidification front and fluid flow in the molten alloy still remains to be understood ..

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Section: Forest-likementioning

confidence: 99%

Materials solidification physics in space

Ratke¹,

Gandin²,

Mathiesen³

et al. 2008

Europhysics News

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“…In a previous study, A1-Si alloy ingots were directionally solidified vertically in a rectangular cavity with bulk liquid flow stirred with a controllable electromagnetic stirrer. [32] Temperature measurements during solidification showed that the electromagnetic stirring resulted in rapid removal of bulk liquid superheat. This is similar to the case in the present study, where forced convection results in a higher cooling rate in the liquid-solid phase region of the sump.…”

Section: A Significant Refinement and Improved Uniformity Of Grain Smentioning

confidence: 99%

Grain Refinement and Improvement of Solidification Defects in Direct-Chill Cast Billets of A4032 Alloy by Melt Conditioning

Zhao

Yang

et al. 2017

Metall Mater Trans B

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Melt-conditioned, direct-chill (MC-DC) casting is an emerging technology to manipulate the solidification process by melt conditioning via intensive shearing in the sump during DC casting to tailor the solidification microstructure and defect formation. When using MC-DC casting technology in an industrial scale DC cast billet of an A4032 aluminum alloy, significant grain refinement and uniform microstructure can be achieved in the primary a-Al phase with fine secondary dendritic arm spacing (SDAS). Improved macrosegregation is quantitatively characterized and correlated with the suppression of channel segregation. The mechanisms for the prevention of channel segregation are attributed to the increased local cooling rate in the liquid-solid phase region in the sump and the formation of fine equiaxed dendritic grains under intensive melt shearing during MC-DC casting. A critical cooling rate has been identified to be around 0.5 to 1 K/s (°C/s) for the channel segregation to happen in the investigated alloy based on quantitative metallographic results of SDAS. Reduction and refinement of microporosity is attributed to the improved permeability in the liquid-solid phase region estimated by the Kozeny-Carman relationship. The potential improvement in the mechanical properties achievable in MC-DC cast billets is indicated by the finer and more uniform forging streamline in the forgings of MC-DC cast billet.

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“…The flow behavior in EM stirred melts is generally controlled by the applied magnetic field used, namely stationary, 2,7,8) rotating, 9) or traveling magnetic fields. 5,10) Moreover, the resulting flow field is highly sensitive to variations in coil design, namely the coil configuration 11,12) and the location of the coil with respect to the melt. 13,14) During past decades, investigations by Evans, 15,16) Fautrelle, 17,18) Szekely, 19) and El-Kaddah 10,20) led to a good understanding of the key flow phenomena in EM stirred melts.…”

Section: Introductionmentioning

confidence: 99%

“…3,4) In addition, it increases fragmentation of the secondary dendrite arms, leading to a higher nucleation potential in the melt. 1,5,6) Clearly, understanding the flow characteristics of an electromagnetically stirred melt in the mushy region is critical in order to control the grain structure of cast alloys.…”

Section: Introductionmentioning

confidence: 99%

Effect of Coil Design on the Temperature and Velocity Fields during Solidification in Electromagnetic Stirring Processes

Poole

El-Kaddah

2014

ISIJ Int.

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This paper examines the role of induction coil design on stirring of molten metal in electromagnetic (EM) solidification processes. A model is presented to describe the EM, heat transfer, and fluid flow phenomena in these processes. It is based on a dual-zone description of the mushy region, and accounts for damping of turbulence by the solidified crystallites. The electromagnetic field equations were solved using the mutual inductance technique, while the temperature and turbulent flow fields were calculated using the control volume method. Calculations were performed for solidification of an Al-Cu alloy placed in a stationary magnetic field generated by an induction coil. The effect of coil design on the flow structure was investigated for three different coil positions. It was found that changing the coil position significantly alters the flow pattern from four recirculating loops when the coil is above the midsection of the melt to two loops, typical of a travelling magnetic field, when the coil is at the base of the melt. This significantly modifies the rate of solidification across the ingot, as well as the temperature gradient, in the mushy region. The decay of the velocity and turbulent fields in the mushy region was found to be exponential, with the maximum rate of decay at the solidification front. These results indicate that through changes in coil design, it is possible to control the flow characteristics and solidification behavior in the molten metal.

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The effect of electromagnetic stirring during solidification on the structure of Al-Si alloys

Cited by 136 publications

References 17 publications

Materials solidification physics in space

Materials solidification physics in space

Grain Refinement and Improvement of Solidification Defects in Direct-Chill Cast Billets of A4032 Alloy by Melt Conditioning

Effect of Coil Design on the Temperature and Velocity Fields during Solidification in Electromagnetic Stirring Processes

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