Reversible nature of shear bands in copper single crystals subjected to iterative shear of ECAP in forward and reverse directions

Miyamoto, Hiroyuki; Ikeda, Takumi; Uenoya, Toshiyuki; Vinogradov, Alexei; Hashimoto, Satoshi

doi:10.1016/j.msea.2010.12.005

Cited by 17 publications

(6 citation statements)

References 36 publications

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“…At the same time, the hardness distribution homogeneity decreased by changing the direction of the shear. The same trend was reported during the shear strain reversal in pure Cu [6,33] and TWIP steel [39]. In the present study, the hardness of Al was decreased by almost 7% after strain reversal, while the decrease in hardness of Cu was 3% after the same amount of strain reversal.…”

Section: Hardnesssupporting

confidence: 90%

“…The competition between dislocation storage and the disappearance of the dislocations accumulated during the forward straining attribute to such action [3,4]. Though the reversal deformation mode cannot significantly affect the grain refinement, the strain reversal potentially delays the formation of high angle grain boundaries (HAGBs) compared with the monotonic deformation one [5,6]. Texture evolution in pure Al subjected to the monotonous and reversal mode in high pressure torsion (HPT) indicates a similar texture in low strain regimes.…”

Section: Introductionmentioning

confidence: 99%

“…The strain reversal takes place during several processing routes such as the cyclic tension-compression [18,19], cyclic torsion [20][21][22], cyclic HPT [7,[23][24][25], ECAP [6,8,9], and simple shear extrusion (SSE) [26][27][28]. Among many processing routes that involve reverse straining, SSE is the newest, and more detailed studies need to be done to understand this phenomenon.…”

Section: Introductionmentioning

confidence: 99%

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Role of Strain Reversal in Microstructure and Texture of Pure Al during Non-Monotonic Simple Shear Straining

et al. 2020

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The effect of reverse straining on the microstructure, texture, and hardness of the pure Al during the single cycle of the simple shear extrusion (SSE) process is investigated. Electron backscattering diffraction (EBSD), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) are used for microstructural evaluations. Due to the nature of the SSE process, the direction of the shear is reversed in the second half channel. As a result, the mean misorientation angle, dislocation density, and hardness decrease. The grain size increases to some extent in the exit of the channel compared with that in the middle. The structural evolution during the single pass of SSE is described in terms of the dislocation cancelling, “untangling” of the cell walls and disintegration of the “forward” cell structure due to the reverse straining in the second half channel. Some simple shear components replace the first texture component in the middle of the channel. At the exit of the channel, the primary texture components appear somewhat confirming the strain reversal effect in the second half channel.

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Section: Hardnesssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Role of Strain Reversal in Microstructure and Texture of Pure Al during Non-Monotonic Simple Shear Straining

et al. 2020

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“…Consequently, based on continuum dislocation mechanics, the components of a dislocation density tensor can be estimated. This method has been used to analyze the dislocation structure of polycrystalline (Kamaya et al, 2005; Calcagnotto et al, 2010; Field et al, 2012) and single crystal materials (Kysar et al, 2007; Miyamoto et al, 2011), the effect of second phase precipitates, and thermal and mechanical strain (Calcagnotto et al, 2010; Karamched & Wilkinson, 2011; Zhang et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Study of Geometrically Necessary Dislocations of a Partially Recrystallized Aluminum Alloy Using 2D EBSD

2019

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During recrystallization, the growth of fresh grains initiated within a deformed microstructure causes dramatic changes in the dislocation structure and density of a heavily deformed matrix. In this paper, the microstructure of a cold rolled and partially recrystallized Al-Mg alloy (AA5052) was studied via electron backscattered diffraction (EBSD) analysis. The structure and density of the geometrically necessary dislocations (GNDs) were predicted using a combination of continuum mechanics and dislocation theory. Accordingly, the Nye dislocation tensor, which determines the GND structure, was estimated by calculation of the lattice curvature. To do so, five components of the Nye dislocation tensor were directly calculated from the local orientation of surface points of the specimen, which was determined by two-dimensional EBSD. The remaining components of GNDs were determined by minimizing a normalized Hamiltonian equation based on dislocation energy. The results show the elimination of low angle boundaries, lattice curvature, and GNDs in recrystallized regions and the formation of low angle boundaries with orientation discontinuities in deformed grains, which may be due to static recovery.

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“…For most metallic materials, the billet is deformed predominantly homogeneously during ECAP [8][9][10]. However, under certain conditions, pronounced strain localization occurs and results in heterogeneous microstructures consisting of regions with large inherent strain (shear bands) and regions with much lower strains (matrix bands) [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Strain Localization during Equal-Channel Angular Pressing Analyzed by Finite Element Simulations

Horn

Silbermann

Frint

et al. 2018

Metals

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Equal-Channel Angular Pressing (ECAP) is a method used to introduce severe plastic deformation into a metallic billet without changing its geometry. In special cases, strain localization occurs and a pattern consisting of regions with high and low deformation (so-called shear and matrix bands) can emerge. This paper studies this phenomenon numerically adopting two-dimensional finite element simulations of one ECAP pass. The mechanical behavior of aluminum is modeled using phenomenological plasticity theory with isotropic or kinematic hardening. The effects of the two different strain hardening types are investigated numerically by systematic parameter studies: while isotropic hardening only causes minor fluctuations in the plastic strain fields, a material with high initial hardening rate and sufficient strain hardening capacity can exhibit pronounced localized deformation after ECAP. The corresponding finite element simulation results show a regular pattern of shear and matrix bands. This result is confirmed experimentally by ECAP-processing of AA6060 material in a severely cold worked condition, where microstructural analysis also reveals the formation of shear and matrix bands. Excellent agreement is found between the experimental and numerical results in terms of shear and matrix band width and length scale. The simulations provide additional insights regarding the evolution of the strain and stress states in shear and matrix bands.

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Reversible nature of shear bands in copper single crystals subjected to iterative shear of ECAP in forward and reverse directions

Cited by 17 publications

References 36 publications

Role of Strain Reversal in Microstructure and Texture of Pure Al during Non-Monotonic Simple Shear Straining

Role of Strain Reversal in Microstructure and Texture of Pure Al during Non-Monotonic Simple Shear Straining

Study of Geometrically Necessary Dislocations of a Partially Recrystallized Aluminum Alloy Using 2D EBSD

Strain Localization during Equal-Channel Angular Pressing Analyzed by Finite Element Simulations

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