Evidence for a stable single component sharp texture in high purity aluminum during tube high-pressure shearing at room temperature

Abstract

A stable {$$\stackrel{\mathrm{-}}{1}{\text{10}}$$ 1 - 10 } <110> single component sharp texture was obtained during ambient temperature tube High-Pressure Shearing (t-HPS) of 99.999% purity aluminum. It is shown that the grain size and the grain aspect ratio saturate at ~ 8 μm and ~ 1.6, respectively, at an equivalent strain of ~ 30 and the high-angle grain boundary fraction continues to decrease after this saturation even to equivalent strains exceeding ~ 200. The {$$\stackrel{\mathrm{-}}{1}{\text{10}}$$ 1 - 10 } <110> texture emerges at an equivalent strain of ~ 6 to 9 with the completion of recrystallization and develops gradually as a sole component sharp texture with increasing intensity upon further processing. This component is a stable orientation in t-HPS processing although it was not previously observed experimentally as a shear texture. Thus, t-HPS processing provides a new and effective experimental tool for simple shear testing that is distinctly different from earlier shear strain methods such as torsional processing.

Tube High-Pressure Shearing: A Simple Shear Path to Unusual Microstructures and Unprecedented Properties

“…9 Evolution of average grain sizes and grain aspect ratios upon increase of t-HPS equivalent strain: grain size obtained from other deformation processing of 5N Al from the literatures are also included for comparison. 14) distribution also approaches the random Mackenzie curve at higher HPTT strain level, as shown in Fig. 11.…”

“…2) The grain size data demonstrates a clear general trend of saturation at 8 « 5 µm where this corresponds to an equivalent strain of ³30, 14) as shown in Fig. 9.…”

“…29) Figures 8 and 9 give an example of data for a 5 nine (5N) high purity Al where the grains were refined by the t-HPS rotations. 14) Some characteristics of this grain refinement are as follows:…”

“…19 Evolution of microstructure parameters: average grain boundary misorientation, HAGB fractions and intensity of f " 110gh110i texture obtained from (111) pole figure, upon increase of t-HPS equivalent strain. 14) Representative data giving further details of the texture evolution are presented in Fig. 21, the (100) pole figures of the as-received 5N Al sample and those after t-HPS rotation to an angle (average equivalent strain) of 10³ (227).…”

“…Furthermore, the disks are usually exceptionally thin and inhomogeneous in the through-thickness directions of disks of some materials, such as magnesium and zirconium alloys, after processing by HPT. 8,9) To remove these strain heterogeneities and to produce relatively large samples, 1012) and also to provide a monotonic deformation process characterized by constant shear direction and strain planarity throughout the deformation process or by simple shear 13,14) to a high strain level, a new friction-driven shear process other than HPT was developed.…”