Microstructural evolution in commercial purity aluminum during high-pressure torsion

Zhilyaev, Alexander P.; Oh-ishi, Keiichiro; Langdon, Terence G.; McNelley, Terry R.

doi:10.1016/j.msea.2005.08.044

Cited by 214 publications

(131 citation statements)

References 10 publications

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“…24) A critical and important feature after N ¼ 1=8 in Fig. 1 is that, similar to the results reported for several different materials, [4][5][6][7][8][9][10][11][12][13]15,16,25,26) the measured hardness in the center of the disk is lower than in the surrounding areas. However, this result differs from earlier measurements on aluminum of 99.99% purity where the measured hardness was consistently higher in the centers of the disks after small numbers of whole revolutions.…”

Section: Microhardness Measurements After Hptsupporting

confidence: 83%

“…4) The gradual evolution towards a more homogeneous structure in disks of Ni was later demonstrated by constructing plots of the hardness values over the disk surfaces after processing through different numbers of torsional revolutions and different applied pressures and these plots demonstrated greater homogeneity at larger numbers of revolutions and higher applied pressures. 5) To date, several reports are now available on the variations of hardness across HPT disks for a range of metals including Al and aluminum alloys, [6][7][8] Cu, 9-11) Ni 12) and steel. 13) It is possible to achieve an excellent pictorial representation of the hardness distributions introduced in HPT by taking large numbers of individual hardness measurements following rectilinear grid patterns on the disk surfaces and then plotting these data in the form of color-coded contour maps.…”

Section: Introductionmentioning

confidence: 99%

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Microstructural Evolution in Pure Aluminum in the Early Stages of Processing by High-Pressure Torsion

Horita

Langdon

2010

Mater. Trans.

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Measurements were taken to evaluate the evolution of homogeneity in disks of high-purity aluminum in the early stages of processing by high-pressure torsion. The results demonstrate that samples processed through 1/4 or more whole revolutions exhibit microhardness values which are generally higher in the centers of the disks than at the edges whereas after 1/8 turn the hardness is higher at the edge than in the center. It is shown that all of the hardness measurements are mutually consistent and they scatter around a unique curve when plotted against the equivalent strain. The measurements of hardness are supplemented by microstructural observations which provide evidence of a gradual evolution in the microstructure with increasing strain from an initial formation of subgrains to an array of ultrafine grains separated by boundaries having high angles of misorientation.

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Section: Microhardness Measurements After Hptsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Microstructural Evolution in Pure Aluminum in the Early Stages of Processing by High-Pressure Torsion

Horita

Langdon

2010

Mater. Trans.

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“…the grain refinement increases from grip towards the fracture region and decreases from the surface towards the centre of the strained samples. Similar changes in hardness across the radius of deformed sample were observed in a series of Al alloys processed by high pressure torsion (HPT), as for example pure Al, 6061 Al alloy, and strengthened Al-Mg alloy [26][27][28][29]. Then, there is clear evidence for evolution towards a more homogeneous microstructure with increasing equivalent strain (or N t ).…”

Section: Microhardness Measurementssupporting

confidence: 55%

Microstructure gradient after hot torsion deformation of powder metallurgical 6061 Al alloy

Eddahbi

Borrego

Monge

et al. 2012

Materials Science and Engineering: A

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Abstract:The microstructure and the texture of extruded 6061 Al alloy processed by powder metallurgy (PM), using three different initial powder particle sizes, have been studied after torsion deformation at 300 • C at strain rate of 6 s −1 . The initial extruded microstructure of the three alloys consisted of elongated grains confining substructure with a typical 1 1 1 + 1 0 0 fiber texture. After torsion deformation, the torque ( ) as a function of the equivalent strain (ε eq ) showed softening and the microstructure exhibited a gradient across the section so that the inner and outer zones contained sheared-elongated and small-equiaxed subgrains, respectively. It was observed that the equivalent strain to failure for the material processed using powder particles size of less than 45 m was of about ε eq ∼ 12, compared to ε eq ∼ 1 for material processed using powder particles size of less than 25 m. The microstructural changes during hot torsion deformation of PM 6061 Al alloy should involve continuous dynamic processes.

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“…Fig. 4 illustrates the results of hardness measurements for a disc along the radial positions [22]. Figure 4.…”

Section: The Hpt Processmentioning

confidence: 99%

Comparing Plastic Deformations Produced by HPT and ECAP Processes Using the Finite Element Analysis Method

Zeynali¹,

Bisadi²

2012

MECHANICS

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Applying Sever Plastic Deformation (SPD) to metals in order to form a nanocrystalline structure in them has been the subject of many recent researches. Investigations show that the nanocrystalline structure improves mechanical properties such as the yield strength and wear resistance. Among the SPD methods, more attention has been paid to the High Pressure Torsion (HPT) and Equal Cannel Angular Pressing (ECAP) methods. Irrespective of different work-piece geometries produced through these methods, studying the amount of plastic deformation as well as the method of applying it could be useful in comparing these processes and choosing the more effective ones. In this article, the results of finite element analysis of the HPT and ECAP processes on pure commercial aluminum are provided and the rate of success of each process in applying the SPD to the part is studied. Plastic deformation is considered as a parameter for calculating the amount of grain refinement. The two methods are compared and their advantages and disadvantages are discussed in the end.

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Microstructural evolution in commercial purity aluminum during high-pressure torsion

Cited by 214 publications

References 10 publications

Microstructural Evolution in Pure Aluminum in the Early Stages of Processing by High-Pressure Torsion

Microstructural Evolution in Pure Aluminum in the Early Stages of Processing by High-Pressure Torsion

Microstructure gradient after hot torsion deformation of powder metallurgical 6061 Al alloy

Comparing Plastic Deformations Produced by HPT and ECAP Processes Using the Finite Element Analysis Method

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