Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

Ahn, Dong-Hyun; Lee, Jun Young; Kang, Minju; Park, Lee Ju; Lee, Sunghak; Kim, Hyoung Seop

doi:10.1007/s11661-016-3326-9

Cited by 4 publications

(5 citation statements)

References 35 publications

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“…For each material, two samples were rolled with the thermocouple attached in the middle of the sample, one for the cryogenic rolling and one for the room temperature rolling. Although the recovery seems to be the most reasonable process at room temperature, some authors such as Dong-Hyun et al 9 and Konkova et al 10 pointed out the recrystallization at RT with these metals. According to that, after completion of the rolling process, specimens were stored at LN 2 until testing, to avoid extensive recovery or even recrystallization at RT, and removed from LN 2 right before each test and the tests were performed immediately after the rollings.…”

Section: Methodsmentioning

confidence: 99%

Study of Cryogenic Rolling of FCC Metals with Different Stacking Fault Energies

et al. 2017

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Aluminum, copper and silver samples, all of them face-centered cubic (FCC) metals, were rolled at room and cryogenic temperatures until equivalent strains (ε) were between 3.23 and 4.13. The cryogenic temperature (CT) and room temperature (RT) rolled samples were evaluated by hardness tests and X-ray diffraction (XRD), which indicate influence of stacking fault energy (SFE) on process. Lower SFE metals tend to exhibit dislocation densities significantly increased and as consequence, hardness too. It was also noted that after sometime exposed to RT, the materials rolled at CT present hardness decrease.

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Section: Methodsmentioning

confidence: 99%

Study of Cryogenic Rolling of FCC Metals with Different Stacking Fault Energies

et al. 2017

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Section: Introductionmentioning

confidence: 99%

“…Most of the high strain rate, severe deformation studies published so far rely on uniaxial compression facilities where the deforming material is unconfined and is allowed to flow freely [5,6]. Such facilities can be of two types: (i) conventional upper-lower anvil type presses [5] or (ii) the split Hopkinson pressure bar system and their adaptations [6]. In addition few studies report the use of torsional deformation devices which can be either torsional Kolsky bar systems [7] or conventional torsion deformation devices [8].…”

Section: Introductionmentioning

confidence: 99%

Dynamic High Pressure Torsion (DHPT)—A Novel Method for High Strain Rate Severe Plastic Deformation

Lanjewar

Kestens

Verleysen

2018

The 18th International Conference on Experimental Mechanics

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Metals with a fine-grained microstructure have exceptional mechanical properties. Severe plastic deformation (SPD) is one of the most successful ways to fabricate ultrafine-grained (UFG) and nanostructured (NC) materials. Most of the SPD techniques employ very low processing speeds. However, the lowest steady-state grain size which can be obtained by SPD is considered to be inversely proportional with the strain rate at which the severe deformation is imposed. In order to overcome this limitation, methods operating at higher rates have been envisaged and used to study the fragmentation process and the properties of the obtained materials. However, almost none of these methods, employ hydrostatic pressures which are needed to prevent the material from failing at high deformation strains. As such, their applicability is limited to materials with a high intrinsic ductility. Additionally, in some methods the microstructural changes are limited to the surface layers of the material. To circumvent these restrictions, a novel facility has been designed and developed which deforms the material at high strain rate under high hydrostatic pressures. Using the facility, commercially pure aluminum was processed and analysis of the deformed material was performed. The microstructure evolution in this material was compared with that observed in static high pressure torsion (HPT) processed material.

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Section: Introductionmentioning

confidence: 99%

“…Most of the high strain rate severe deformation studies published so far rely on uniaxial compression facilities where deforming material is unconfined and is free to flow in other directions [2][3][4][5][6][7]. Such compression facilities are either of conventional upper-lower anvil type [2][3][4] or based on the split Hopkinson bar system [5][6][7]. Few of the studies involved application of torsional deformation using either a torsional Kolsky bar system [8][9] or conventional torsion deformation devices [10], again without any confinement of the deforming material which necessarily limits the amount of strain applied without material failure and can only be applied for materials with high intrinsic ductility.…”

Section: Introductionmentioning

confidence: 99%

A novel method for severe plastic deformation at high strain rate

2018

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Severe plastic deformation (SPD) processing is defined as any method of forming under an extensive hydrostatic pressure that may be used to impart a very high strain to a bulk solid without any significant change in dimensions of the sample, producing exceptional grain refinement. Most of the SPD techniques employ very low processing speeds, however increased deformation rates are known to have a significant effect on the final microstructure. Most of the SPD processes operating at high rates do not impose hydrostatic pressures to the material and can therefore only be used for very ductile materials, while in others, the microstructural changes are limited to the surface layers of the material. To circumvent these restrictions a novel facility has been designed and developed where high hydrostatic pressures are maintained while a high shear deformation is imposed at high strain rates. The device combines the features of a high pressure torsion (HPT) unit with the principle of a torsional split Hopkinson bar (SHB) setup. A small ring-like sample, placed between two molds, is first subjected to a high, static pressure and subsequently to a high speed shear deformation upon release of torsional energy stored in a long bar. Although, the principle is rather straightforward, the design of the setup was extremely critical because of the high forces and energies involved. Tests have been performed on commercially pure aluminum. The material hardness increased in accordance with the microstructure and processing conditions; viz. annealed, only compressed and applied shear strain. Deformed grains departed from equiaxed shape and showed morphological texture in the direction of the shear even at very low strains indicating the presence of shear strains in the material. Further the material, or more specifically its mechanical properties and microstructure evolution is compared with conventional, statically deformed HPT samples.

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Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

Cited by 4 publications

References 35 publications

Study of Cryogenic Rolling of FCC Metals with Different Stacking Fault Energies

Study of Cryogenic Rolling of FCC Metals with Different Stacking Fault Energies

Dynamic High Pressure Torsion (DHPT)—A Novel Method for High Strain Rate Severe Plastic Deformation

A novel method for severe plastic deformation at high strain rate

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