Microstructure and texture evolution of copper processed by differential speed rolling with various speed asymmetry coefficient

Polkowski, Wojciech; Jóźwik, Paweł; Polański, Marek; Bojar, Z.

doi:10.1016/j.msea.2012.12.006

Cited by 52 publications

(34 citation statements)

References 18 publications

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“…Moreover, a decrease of calculated standard deviation values upon raising the roll speed mismatch confirms a more homogeneous course of deformation with the presence of additional shear strain. This finding is in line with the results of previously reported works on various DSRprocessed materials (e.g., Al [32] and Cu [11] ) and may be related to a decrease in surface frictional stresses (which are cited as the main reason for the nonuniformity of deformation upon rolling [33] ) with a rise in roll speed mismatch.…”

Section: Strain Changes During Rollingsupporting

confidence: 92%

“…Additionally, in the case of precipitationstrengthened AZ91Mg-based alloy, an application of DSR results in both an ultrafine grain size (~300 nm) and more uniform distribution of strengthening particles upon postdeformation low-temperature aging treatment. [10] The results of our previous study on commercially pure copper [11] also point out that a shear strain imposed during rolling with different values of roll velocity allows obtainment of material with grain size in the submicron range and a high fraction of HAGBs, indicating dynamic transformation of the microstructure. Moreover, we recently showed that the DSR method also may be successfully applied to improvement of mechanical properties of hardly deformable materials such as intermetallic-based alloys.…”

Section: Introductionmentioning

confidence: 85%

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Electron Backscatter Diffraction Study on Microstructure, Texture, and Strain Evolution in Armco Iron Severely Deformed by the Differential Speed Rolling Method

Polkowski

Jóźwik

Bojar

2015

Metall Mater Trans A

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Results of the electron backscatter diffraction (EBSD) study on structural changes in Armco iron subjected to severe plastic deformation by differential speed rolling (DSR) with different values of roll speed mismatch (R = 1, 2, 3, and 4) are shown in the present article. Results of the EBSD microstructure evaluation reveal that a differentiation of roll speeds results in an effect of structure refinement-iron samples processed with high roll speed mismatch are characterized by a high fraction of grains with submicron size. A microtexture examination shows that the DSR process leads to an overall texture weakening effect and a displacement (a shifting to different ''stable'' positions) of the basic rolling texture components, due to an additional presence of a simple shear component in the deformation gradient imposed to the material. Despite the higher hardness of the DSR-processed samples, results of the EBSD strain analysis indicate that some part of the stored deformation energy is released during rolling with an additional presence of shear strain. This finding points toward the possibility of activating a dynamic transformation of the material structure into some more stable state. However, since the observed structural changes take place inside deformation bands and do not lead directly to the formation of a fully equiaxed grain structure, it seems to be more reasonable to call the observed structure transformation a subgrain structure evolution through accumulated shear deformation, which may be related to the dynamic recovery process.

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Section: Strain Changes During Rollingsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 85%

Electron Backscatter Diffraction Study on Microstructure, Texture, and Strain Evolution in Armco Iron Severely Deformed by the Differential Speed Rolling Method

Polkowski

Jóźwik

Bojar

2015

Metall Mater Trans A

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“…New grains appear in the material which can achieve nanometric size and a large misorientation angle ([15°) if the width of the microbands is also sufficiently small (\500 nm). This mechanism is called the ''geometric mechanism of new grains formation'' [20][21][22][23][24]. The formation of ultrafinegrained structure is caused by a change in the direction of deformation (e.g., by rotation of sample) resulting in additional intersecting microbands.…”

Section: Introductionmentioning

confidence: 99%

“…The new grains are usually characterized by a bimodal misorientation distribution, exhibiting low and high misorientation angles. With increasing applied strain, there is a gradual increase in the average misorientation angle of newly formed boundaries and the fraction of high-angle grain boundaries [24,25]. In this paper, multi-axis compression is applied by using the MAXStrain Ò unit to impose cyclic compression in two mutually orthogonal directions.…”

Section: Introductionmentioning

confidence: 99%

Multi-axial forging of Fe3Al-base intermetallic alloy and its mechanical properties

2016

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Tri-axial plane-strain forging was applied to the Fe-28Al-5Cr-0.8Zr-0.04B intermetallic alloy, in order to study its grain refinement and possible improvement in mechanical properties. The forging temperature range was from 20 to 600°C. The maximum number of forging passes was 67. The deformed microstructure was investigated using electron backscatter diffraction in a scanning electron microscope. At forging temperatures \500°C, the alloy was very prone to brittle cracking. At the temperature range of 500-600°C, the overall plasticity of material increased and the cracking tendency was reduced but not completely eliminated. Extensive processes of dynamic recovery/recrystallization were observed during forging at 600°C after 10-40 passes. Recrystallized areas with an average grain size of a few micrometers were observed. However, even after severe deformation at 600°C, resulting from 40 forging passes (e * 11.3), dynamic recrystallization was incomplete and the fraction of low-angle boundaries was still high. The Vickers microhardness substantially increased from 280 HV0.1 to 450 HV0.1 at the center of the sample after both deformations at room temperature as well as after 20-40 cycles at 500-600°C. However, a further increase of strain for a sample deformed at 600°C after 67 passes (e * 28) led to quite a significant hardness decrease at the center of the sample. This phenomenon could be associated with the initiation of dynamic recrystallization. None of the samples forged at the 500-600°C range exhibited any ductility improvement during subsequent tensile testing at room temperature, most likely, owing to the absence of a uniform ultrafine-grained structure developed during forging.

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“…For ESR, shear deformation is restricted to the near surface region [8,9]. In the case of DSR, the volume that is affected by shear is strongly material dependent as shown in numerous studies on different materials, e.g., steel, copper, aluminium and niobium [3,[10][11][12][13][14][15]. Special attention is paid to the investigation of DSR of hexagonal metals such as magnesium [4,[16][17][18] and titanium [6,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Ti/Al Multi-Layered Sheets: Differential Speed Rolling (Part B)

Romberg

Freudenberger

Watanabe

et al. 2016

Metals

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Differential speed rolling has been applied to multi-layered Ti/Al composite sheets, obtained from accumulative roll bonding with intermediate heat treatments being applied. In comparison to conventional rolling, differential speed rolling is more efficient in strengthening the composite due to the more pronounced grain refinement. Severe plastic deformation by means of rolling becomes feasible if the evolution of common rolling textures in the Ti layers is retarded. In this condition, a maximum strength level of the composites is achieved, i.e., an ultimate tensile strength of 464 MPa, while the strain to failure amounts to 6.8%. The deformation has been observed for multi-layered composites. In combination with the analysis of the microstructure, this has been correlated to the mechanical properties.

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Microstructure and texture evolution of copper processed by differential speed rolling with various speed asymmetry coefficient

Cited by 52 publications

References 18 publications

Electron Backscatter Diffraction Study on Microstructure, Texture, and Strain Evolution in Armco Iron Severely Deformed by the Differential Speed Rolling Method

Electron Backscatter Diffraction Study on Microstructure, Texture, and Strain Evolution in Armco Iron Severely Deformed by the Differential Speed Rolling Method

Multi-axial forging of Fe3Al-base intermetallic alloy and its mechanical properties

Ti/Al Multi-Layered Sheets: Differential Speed Rolling (Part B)

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