Modeling Direct Chill Casting of Aluminum Alloys Cathryn Karashin Advisor: Dr. Krane

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

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

DC Casting: Mold and Ingot Photos courtesy of M. Krane

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

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

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

Progress of Models 1 st Model: pure Al, simple cooling using fixed values 2 nd Model: pure Al, simple cooling using fixed values, solidification 3 rd Model: Al-Cu 5%, cooling using heat transfer coefficient, solidification

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

Wedge to Cube

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

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

Cube Simulations 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: Dr. Krane All the grad students that have helped me when I’m stuck in the lab Purdue