Possibilities Of Aluminium Extrusion By The ECAP Method

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Possibilities Of Aluminium Extrusion By The ECAP
Method

• Miroslav Greger - VŠB Technical University of
  Ostrava
• Stanislav Rusz - VŠB Technical University of
  Ostrava

2
Introduction

• The technology ECAP allows to obtain an
  ultra-fine grain in larger volumes, moreover
  without change of original cross-section of the
  input semi-product. It is possible to use the
  obtained materials in automotive industry, in
  military and aerospace industries.

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Principles of ECAP
Fig. 1. Schematic illustration of equal channel
angular pressing process (ECAP)
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Principles of Shearing on Passage Through the
ECAP Die
Route A
Route BA
90
Route C
Route BC
180
90
Fig. 2. The four processing routes in ECAP
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Shearing Patterns Associated with the Different
Processing Routes
Z plane
Y plane
X plane
X
Z
Z
Y
Y
X
Fig. 3. Shearing associated by a single passage
through the die
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Influences of the Forming Parameters on Plastic
Deformation

• Influence of inner energy
• Non-homogeneity of deformation
• Density of dislocation
• Concentration of vacancies

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Change of Dislocation Substructure
Fig. 4. Scheme of change of dislocation
sub-structure after cold deformation
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Dependencies
Linear dependence of dislocation density
Flow stress necessary for continuing of
deformation
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Experimental Verification
Fig. 5. Overall view on the forming equipment and
die
Fig. 6. Detailed view on the extruding punch for
the ECAP technology
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Samples for Extrusion
Fig. 7. Initial sample and samples after extrusion
Fig. 8. Structure in the central area
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Deformation Resistance
Fig. 9. Deformation resistance of the aluminium
Fig. 10. Deformation resistance of the alloy
AlCuMg
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Micro-structure of Sample After Extrusion
Fig. 11. The first passage
Fig. 12. The second passage
Fig. 14. The fourth passage
Fig. 13. The third passage
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Conclusion

• Refining of grain in poly-crystalline metals.
• Micro-structure obtained by ECAP method depends
  on
• Using of more passes and turning of the sample.
• Extruding the sample by 4 or more passes.
• Optimal angle between horizontal and vertical
  channel of the part is 90 degrees. Radius of
  fillet of the extrusion channel must correspond
  to conditions for steady flow of metal.
• Strain rate has only partial influence on
  deformation resistance and small influence on
  micro-structure.

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Practical Illustration of the ECAP Method by
Mathematic Modeling
Fig. 15. The example of stress intensity by the
simulation process of the AlCuMg extrusion (1st
and 2nd sample)
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Practical Illustration of the ECAP Method by
Mathematic Modeling
Fig. 16. The example of shear stresses partition
by the ECAP method (1st a 2nd sample)
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Practical Illustration of the ECAP Method by
Mathematic Modeling
Fig. 17. Contact pressure between sample and
tools for AlCuMg alloy by the ECAP method (1st a
2nd sample)
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Practical Illustration of the ECAP Method by
Mathematic Modeling
Fig. 18. The example of the deformation intensity
of AlCuMg alloy by the ECAP method (1st a 2nd
sample)
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Practical Illustration of the ECAP Method by
Mathematic Modeling
Fig. 19. The example of the lay-out of
temperature of AlCuMg alloy by the ECAP method
(1st a 2nd sample)
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• Thank you for your attention