Modeling Direct Chill Casting of Aluminum Alloys

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Modeling Direct Chill Casting of Aluminum Alloys

• Cathryn Karashin
• Advisor Dr. Krane

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Aluminum Applications

• Beverage cans, planes, trains, automobiles,
  boats, spacecraft parts
• Used as the mold material in Al casting
• Al is very lightweight (1/3 the weight of steel)
  so it is very useful

Picture courtesy of Aluminum Technology,
Applications, and Environment by Dietrich G.
Altenpohl
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Direct Chill Casting

• Direct chill (DC) casting process is used for 68
  of the aluminum ingots processed in the US
• Ingot scrap from stress cracks and butt
  deformation account for a 5 loss in production
• Control of scrap levels is important both in
  terms of energy usage and cost savings

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DC Casting Mold and Ingot
Photos courtesy of M. Krane
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Sump Depth

• Sump depth at start up?
• Flood et al. believe the sump increases at start
  up, then decreases and plateaus
• Through modeling, we hope to have a more definite
  answer

A scaling Analysis for the Heat Flow,
Solidification Convection in Continuous Casting
of Aluminum by Flood, Davidson, Rogers
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Physica Version 2.11

• Models thermal and mechanical properties
• Puts continuous equations into discrete parts
  breaking down into simple algebraic terms
• Produces a results file that can be used to
  generate graphs and analyze data

Photo courtesy of http//www.gre.ac.uk/physica
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Project Objectives

• To model heat transfer and solidification
  phenomena in direct chill casting using Physica
  software
• To study sump shapes during start up as basis for
  future stress analysis

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Progress of Models

• 1st Model pure Al, simple cooling using fixed
  values
• 2nd Model pure Al, simple cooling using fixed
  values, solidification
• 3rd Model Al-Cu 5, cooling using heat transfer
  coefficient, solidification

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Wedge Gone Bad

• Started using simulations with a wedge
• Axisymmetric properties of wedge made it ideal
• Problem with geometry of translating smaller
  wedge to larger wedge

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Wedge to Cube
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Simulations with the Cube

• pure Al, simple cooling using fixed values,
  solidification
• Pure Al, simple cooling using fixed values,
  solidification, fluid flow
• Pure Al, simple cooling using fixed values from
  only side mold wall, solidification, fluid flow

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Cube Simulations

• Cooling from sides and bottom
• Notice liquid center (red) and solidified region
  (blue)

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Cube Simulations

• Cooling from side only
• Notice liquid center (red) and solidified region
  (blue)
• Note large different between this and previous
  plot

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Resultant Velocity at 20s
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Liquid Fraction at 400s
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Thanks to

• Dr. Krane
• All the grad students that have helped me when
  Im stuck in the lab
• Purdue ?