Expansion equal channel angular extrusion, as a novel severe plastic deformation technique

Sepahi-Boroujeni, Saeid; Fereshteh-Saniee, F.

doi:10.1007/s10853-015-8937-9

Cited by 31 publications

(11 citation statements)

References 44 publications

(52 reference statements)

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“…In the next passage, the deformation increases and undergo propagates, which leads to a more uniform distribution. As a result of re-passing through the shear plane, the grains return to equiaxed, especially in the III-area (Figure 9d), which is consistent with previous reports [10,48,49]. The structure becomes slightly more fine-grained.…”

Section: Simulation Of Cross-channel Extrusion—results and Discussionsupporting

confidence: 91%

Severe Plastic Deformation of Fe-22Al-5Cr Alloy by Cross-Channel Extrusion with Back Pressure

Łyszkowski

Polkowski²,

Czujko

2018

Materials

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A new concept of the cross-channel extrusion (CCE) process under back pressure (BP) was proposed and tested experimentally. The obtained by finite element method (FEM) results showed that a triaxial compression occurred in the central zone, whereas the material was deformed by shearing in the outer zone. This led to the presence of a relatively uniformly deformed outer zone at 1 per pass and a strong deformation of the paraxial zone (3–5/pass). An increase in the BP did not substantially affect the accumulated strain but made it more uniform. The FEM results were verified using the physical modeling technique (PMT) by the extrusion of clay billet. The formation of the plane of the strongly flattened, and elongated grains were observed in the extrusion directions. With the increase in the number of passes, the shape of the resulting patterns expanded, indicating an increase in the deformation homogeneity. Finally, these investigations were verified experimentally for Fe-22Al-5Cr (at. %) alloy using of the purposely designed tooling. The effect of the CCE process is the fragmentation of the original material structure by dividing the primary grains. The complexity of the stress state leads to the rapid growth of microshear bands (MSB), grain defragmentation and the nucleation of new dynamically recrystallized grains about 200–400 nm size.

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Section: Simulation Of Cross-channel Extrusion—results and Discussionsupporting

confidence: 91%

Severe Plastic Deformation of Fe-22Al-5Cr Alloy by Cross-Channel Extrusion with Back Pressure

Łyszkowski

Polkowski²,

Czujko

2018

Materials

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“…They include an inlet channel with variable cross-section, additional twist and small angular steps [68,69]; transverse shear and expanding zone between channels [70,71]; an additional area reduction step in the outlet channel [72]. These and similar modifications significantly increase extrusion pressure, decrease a billet length and require extrusion "billet-bybillet" without channel lubrication and inspection.…”

Section: Modifications Of Ecaementioning

confidence: 99%

Review: Modes and Processes of Severe Plastic Deformation

Segal¹

2018

Preprint

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In this review, severe plastic deformation (SPD) is considered as a materials processing technology. The deformation mode is the principal characteristic differentiating SPD techniques from common forming operations. For large plastic strains, deformation mode depends on the distribution of strain rates between continuum slip lines and can be varied from pure shear to simple shear. A scalar, invariant and dimensionless coefficient of deformation mode is introduced as a normalized speed of rigid rotation. On this basis, simple shear provides the optimal mode for structure modification and grain refinement whereas pure shear is "ideal" for forming operations. Special experiments and SPD practice confirm this conclusion. Various techniques of SPD are classified and described in accordance with simple shear realization or approximation. It is shown that correct analyses of the processing mechanics and technological parameters are essential for comparison of SPD techniques and the development of effective industrial technologies.

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“…(d) Several attempts have been made to increase strain intensity and to reduce the number of ECAE passes. They include an inlet channel with a variable cross-section, additional twist, and small angular steps [ 68 , 69 ]; a transverse shear and expanding zone between channels [ 70 , 71 ]; and an additional area reduction step in the outlet channel [ 72 ]. These and similar modifications significantly increase extrusion pressure, decrease the billet length, and require extrusion “billet-by-billet” without channel lubrication and inspection.…”

Section: Processes Of Spdmentioning

confidence: 99%

Review: Modes and Processes of Severe Plastic Deformation (SPD)

Segal

2018

Materials

144

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In this review, severe plastic deformation (SPD) is considered as a materials processing technology. The deformation mode is the principal characteristic differentiating SPD techniques from common forming operations. For large plastic strains, deformation mode depends on the distribution of strain rates between continuum slip lines and can be varied from pure shear to simple shear. A scalar, invariant, and dimensionless coefficient of deformation mode is introduced as a normalized speed of rigid rotation. On this basis, simple shear provides the optimal mode for structure modification and grain refinement, whereas pure shear is “ideal” for forming operations. Special experiments and SPD practice confirm this conclusion. Various techniques of SPD are classified and described in accordance with simple shear realization or approximation. It is shown that correct analyses of the processing mechanics and technological parameters are essential for the comparison of SPD techniques and the development of effective industrial technologies.

show abstract

Expansion equal channel angular extrusion, as a novel severe plastic deformation technique

Cited by 31 publications

References 44 publications

Severe Plastic Deformation of Fe-22Al-5Cr Alloy by Cross-Channel Extrusion with Back Pressure

Severe Plastic Deformation of Fe-22Al-5Cr Alloy by Cross-Channel Extrusion with Back Pressure

Review: Modes and Processes of Severe Plastic Deformation

Review: Modes and Processes of Severe Plastic Deformation (SPD)

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