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Innovative Methodologies to Increase Productivity

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Innovative Methodologies to Increase Productivity by Simulating Development of Structure during Extrusion and Solution Soaking

Terry Sheppard, Bournemouth University, Bournemouth, Dorset, UK

Track: EXTRUSION/DIE, THEORETICAL - Microstructure

ABSTRACT --- Materials which form the surface and subcutaneous layers of an
extrudate experience large deformations when they traverse the die land, which
when added to the inhomogeneity caused by the dead metal zone, leads to
considerable modifications to the deformation parameters when compared to the
remainder of the extrusion. The distribution of structure and of properties is
therefore greatly inhomogeneous. The variation in the extrudate properties due
to this factor are presented and discussed. Reference to both empirical and
physical models of the recrystallization process indicates that nucleation and
growth will differ at these locations in those alloys that are usually solution
treated and aged subsequent to the deformation process. Since static
recrystallization has a significant influence on many of the properties of the
extrudate, it is therefore essential to provide the methodology to predict these
variations. Critically, it is shown, that the grain boundary migration, previously
stated to be constant, must be correctly represented as temperature dependent. In
the work presented here, a physical model based on dislocation density, subgrain
size, and misorientation is revised and integrated into the commercial finite
element method (FEM) code, FORGE, to study the microstructure changes. A
scaled representation of a wing spar is used as illustration. The evolution of the
substructure influencing static recrystallization is studied. The predicted results
show an agreement with the experimental measurement. Importantly, the
properties of hard alloys improve as the temperature of the extrusion is raised.
This phenomenon is discussed and theoretically justified.

© Extrusion Technology for Aluminum Profiles Foundation (ET Foundation). All rights reserved. No part of The Proceedings may be reproduced in any form without the express written permission of the ET Foundation.