Transcript Modeling Direct Chill Casting of Aluminum Alloys

Modeling Direct Chill Casting of
Aluminum Alloys
Cathryn Karashin
Advisor: Dr. Krane
Aluminum Applications
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Picture courtesy of Aluminum: Technology, Applications, and
Environment by Dietrich G. Altenpohl
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
Direct Chill Casting
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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
DC Casting: Mold and Ingot
Photos courtesy of M. Krane
Sump Depth
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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
Physica Version 2.11
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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
Project Objectives
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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
Progress of Models
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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
Wedge Gone Bad
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Started using
simulations with a wedge
Axisymmetric properties
of wedge made it ideal
Problem with geometry
of translating smaller
wedge to larger wedge
Wedge to Cube
Simulations with the Cube
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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
Cube Simulations
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Cooling from sides and
bottom
Notice liquid center (red)
and solidified region
(blue)
Cube Simulations
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Cooling from side only
Notice liquid center (red)
and solidified region
(blue)
Note large different
between this and
previous plot
Resultant Velocity at 20s
Liquid Fraction at 400s
Thanks to:
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Dr. Krane
All the grad students that have helped me
when I’m stuck in the lab
Purdue 