Jet processing of direct chill cast aluminum ingots
Author(s)Wagstaff, Samuel Robert
Massachusetts Institute of Technology. Department of Materials Science and Engineering.
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Macrosegregation of solute elements during casting operations has been a subject of observation, discussion, and research for several hundred years. The unique casting conditions found in the Direct-Chill aluminum casting process can lead to significant accumulation and depletion of solute elements throughout the cast product. In particular, the center of ingots are generally characterized by a depletion of up to 20 % of solute elements. In this investigation we confirm the dominant role mobile, solute-depleted grains play on magrosegregation along ingot centerlines. We propose that avalanche events drive the grains from the solidification front to the ingot center. In order to demonstrate and control this preferential settling, we propose the use of a turbulent jet to re-suspend the avalanching grains. An analytical expression is derived in order to optimize the dimension of the jet with the goal of minimizing centerline segregation. We then performed a series of experiments in order to validate the analytical expression across ingot dimensions and alloy families. Our experiments indicate that the use of a properly sized turbulent jet can reduce the degree of centerline segregation by up to 70% from standard conditions.
Thesis: Sc. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.Cataloged from PDF version of thesis.Includes bibliographical references.
DepartmentMassachusetts Institute of Technology. Department of Materials Science and Engineering.
Massachusetts Institute of Technology
Materials Science and Engineering.