Experimental Techniques to Characterize Large Plastic Deformations in Unlubricated Hot Aluminum Extrusion |
| Journal |
Key Engineering Materials (Volume 367) |
| Volume |
Advances on Extrusion Technology and Simulation of Light Alloys |
| Edited by |
Luca Tomesani and Lorenzo Donati |
| Pages |
17-24 |
| DOI |
10.4028/www.scientific.net/KEM.367.17 |
| Online since |
February, 2008 |
| Authors |
Henry Valberg
|
| Keywords |
Deformation, Experimental Analysis, Extrusion, Grid Pattern Technique, Metal Flow |
| Abstract |
A review is given of experimental work done at the author’s university during the last
two decades, to investigate metal flow in aluminum extrusion.
Partially extruded billets with internal grid patterns are difficult to remove from the container
without post-deforming the internal pattern during the removal operation. A technique was
therefore developed by which such billets can be removed from the container without any damage.
In addition to this, a special grid pattern technique was developed. This technique applies contrast
material stripes in the symmetry plane of the billet, and is advantageous because the pattern
obtained remains clearly visible after extrusion, even in shear zones subjected to very heavy
deformations. Traditional scratched patterns become invisible in such regions, and do not provide
metal flow information in shear zones.
When the two techniques, i.e. the new removal technique and the new grid pattern technique, were
used concurrently, “perfect” type of metal flow experiments were conducted.
A three-dimensional grid pattern technique was also developed. It is well suited for characterization
of metal flow in complex shape extrusion, when there is no symmetry plane in which to conduct
traditional grid pattern analysis.
Applications of the new techniques for metal flow studies in various cases of extrusion are reported.
It is shown that precise metal flow information indeed is a necessary requirement to get metal flow
correct in computer simulation. |
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