Introduction
Materials and Methods
[wt.%] | Fe | Si | Cu | Zn | Ti | Mn | Mg | Ni | Cr | Pb | Be | Al |
---|---|---|---|---|---|---|---|---|---|---|---|---|
AlMg3 | 0.096 | 0.076 | 0.007 | 0.005 | 0.004 | 0.004 | 3.06 | 0.006 | 0.001 | 0.001 | 0.006 | 96.73 |
AlMg7.5 | 0.16 | 0.08 | 0.001 | … | 0.016 | 0.006 | 7.52 | 0.002 | … | 0.003 | … | 92.21 |
Initial diameter do, mm | Final diameter df, mm | Reduction R (d02/df2) | Cumulative reduction Rcum | True strain e (lnR) | Cumulative true strain ecum | Linear speed, mm/sec | Strain rate, s-1 | Extrusion pressure pHE, MPa | |
---|---|---|---|---|---|---|---|---|---|
AlMg3 ε1 | 20 | 13 | 2.37 | 2.37 | 0.86 | 0.86 | 66.27 | 2.32E+00 | 284 |
AlMg3 ε2 | 13 | 10 | 1.69 | 4 | 1.39 | 2.25 | 112.00 | 8.45E+00 | 264 |
AlMg7.5 ε1 | 20 | 13 | 2.37 | 2.37 | 0.86 | 0.86 | 66.27 | 2.32E+00 | 397 |
AlMg7.5 ε2 | 13 | 10 | 1.69 | 4 | 1.39 | 2.25 | 112.00 | 8.45E+00 | 375 |
Results and Discussion
Microstructures
Tensile Properties
Conclusions
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Deformation of the fully-developed equiaxial microstructures is observed in both alloys after HE. After the first step of HE an increased density of dislocations, locally formed substructures and newly formed grains are present. The second step of deformation brings a minor intensification of the microstructural transformations
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A significant improvement of the maximal tensile strength occurred after the first step of HE, at the same time the elongation was drastically decreased. The second degree of deformation did not bring any significant alterations in the mechanical parameters.
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The true strains imposed during the process of HE in this research were relatively low, when compared to the literature [e. g. (Ref 5, 12, 28, 47, 48)]. However, significant increase of strength was obtained in both alloys. Hence, this method has a potential to be considered an attractive alternative for the commonly used methods of large plastic deformation.