Evaluation of the Applicability of a Thermomechanical Model to Industrial Extrusion Experiments of AA6063
J. van de Langkruis, Corus Research, Development and Technology, W. H. Kool, Delft University of Technology, S. van der Zwaag, Delft University of Technology
Track: EXTRUSION PROCESS - Extrusion Process
ABSTRACT --- A constitutive model and particle dissolution model were applied to
quantify the effect of the Mg and Si solute content on the flow stress under industrial
extrusion conditions. For the constitutive model, a hyperbolic sine law was adapted to take
into account the effect of solute Mg and Si. The parameters in this model were derived
from plane strain compression data. The amounts of solute Mg and Si during deformation
were calculated with the particle dissolution model. Extrusion billets with different initial
Mg2Si distributions were extruded with an industrial extrusion press. During extrusion,
pressure and temperature were monitored. The extrusion pressures found are rather
insensitive to the initial Mg2Si distributions, whereas the model predicts a significant effect.
In an earlier plane strain compression study, good agreement between model predictions
and experiments was obtained. The deviation of the model predictions with the extrusion
results, found in this study, are attributed to an enhanced dissolution of Mg2Si precipitates
during extrusion. Instead of using a ’static’ (i.e., non-deformation conditions) diffusion
coefficient from literature, a more appropriate diffusion coefficient should be used,
accounting for the generation of dislocations. It is concluded that the effect of enhanced
dissolution makes industrial extrusion less sensitive to the initial billet condition.
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