Dynamic evolution of fine grained structure and superplasticity of 7075 aluminum alloy

Sakai, Taku; Yang, Xuyue; Miura, Hiromi

doi:10.1016/s0921-5093(97)00398-5

Cited by 47 publications

(26 citation statements)

References 11 publications

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“…1,5,6) These aluminum alloys are subjected to extensive cold or warm rolling followed by heating to temperatures of superplastic deformation. 1,5,6,[10][11][12][13][14][15][16][17][18][19][20] Dispersion particles prevent static recrystallization of the warm/cold worked material, and plastic deformation induces high-angle boundaries (HAB) via a continuous reaction called as continuous dynamic recrystallization (CDRX). 1,[12][13][14][15][16][17][18][19][20] The dispersoids effectively pin the deformation-induced boundaries preventing much of the low-angle boundary (LAB) migration resulting in their mutual elimination 21) and also growth of recrystallized grains as well that provides capability for superplasticity.…”

Section: Introductionmentioning

confidence: 99%

“…It was recently suggested that GBS along HABs can result in rotation of subgrains near the HABs, leading to a rapid transformation of the subgrains into true recrystallized grains. 13,15,23) There are, however, limited research works provided direct evidence for operation of GBS in unrecrystallized structure. Thus, the second aim of this study is to reveal the role of GBS in microstructural evolution during superplastic deformation and to relate the microstructure evolved with mechanical response of the material.…”

Section: Introductionmentioning

confidence: 99%

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The Role of Grain Boundary Sliding in Microstructural Evolution during Superplastic Deformation of a 7055 Aluminum Alloy

et al. 2002

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The microstructure evolution in a 7055 aluminum alloy subjected to thermomechanical processing (TMP) was studied at 450 • C anḋ ε = 1.7 × 10 −3 s −1 at which the material exhibits superplastic behavior with a total elongation of 720% and the coefficient m = 0.58. Partially recrystallized initial structure of the as-processed 7055 Al consisted of bands of recrystallized grains with a mean size of 11 µm alternating with bands of recovered subgrains with a mean size of 2 µm. The true stress-true strain curve exhibits a well-defined peak stress, followed by gradual strain softening. The coefficient of strain rate sensitivity, m, remains unchanged at ε ≤ 1 and tends to decrease with strain at ε > 1. The initial microstructure persists near the peak strain. Following strain leads to evolution of initial partially recrystallized structure into uniform fully recrystallized structure due to occurrence of continuous dynamic reactions, i.e. continuous dynamic recrystallization (CDRX). The data of microstructural observation and misorientation analysis show that low-angle boundaries (LAB) gradually convert to high-angle boundaries (HAB) resulting in an extensive flow softening. It was shown that grain boundary sliding (GBS) provides superplastic flow at all strains. Concurrently, GBS plays an important role in the dynamic evolution of new grains facilitating conversion of LABs to HABs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Role of Grain Boundary Sliding in Microstructural Evolution during Superplastic Deformation of a 7055 Aluminum Alloy

et al. 2002

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“…[7] The selection of optimum combinations of strain rate and temperature becomes important for the subgrain rotation mechanism to operate, leading to continuous recrystallization during superplastic deformation of these alloys. [7,8] The chemical composition of the Al alloy 7449 used in this work is shown in Table I. The alloy was prepared in an induction furnace under argon atmosphere, homogenized, and scalped.…”

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confidence: 99%

Superplastic Behavior of a High-Strength Al-Zn-Mg-Cu-Zr Alloy

Kumar

Mukhopadhyay

Prasad

2008

Metall Mater Trans A

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The present study examines the superplastic potential of Al-Zn-Mg-Cu-Zr alloy AA 7449. It is demonstrated that the use of a suitable thermomechanical process (TMP) prior to superplastic deformation, together with the use of appropriate combinations of strain rate and temperature during the tensile test, enabled development of grain structures amenable (having an average grain size of <10 lm) to superplastic deformation in this alloy. This yielded as high as 460 pct elongation.

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“…Formation mechanisms of fine grains by continuous DRX are reported as follows. 8,12,13) Inhomogeneous local strains are induced by grain boundary shearing near grain boundaries of the initial coarse grain, and the local dislocation density increases. The dislocations are rearranged and a subboundary is formed.…”

Section: Resultsmentioning

confidence: 99%

Effect of Zr Addition on Dynamic Recrystallization during Hot Extrusion in Al Alloys

et al. 2005

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The presence of Al 3 Zr precipitates promotes continuous dynamic recrystallization in Al-Zn-Mg alloys during hot extrusion, resulting in a fine-grained structure. The mechanism for this phenomenon was investigated by observing the change in microstructure under hot extrusion using high resolution EBSP. In the rear of the extrusion die mouth, grain boundary mobility is low since the flow stress is comparatively low and grain boundary migration is inhibited by Al 3 Zr particles. Thus, in order to reduce the deformation-induced high dislocation density, continuous dynamic recrystallization occurs, which does not involve long-range grain boundary migration, resulting in a finer-grained structure. The flow stress, and hence, the mobility of the grain boundary increase near the die mouth. This promotes long-range grain boundary migration, which reduces the dislocation density. Continuous dynamic recrystallization is not observed under these conditions. Since Al 3 Zr precipitates inhibit long-range grain boundary migration, increase of the Al 3 Zr precipitate content expands the region where continuous dynamic recrystallization occurs towards the die mouth, resulting in a finer-grained structure.

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Dynamic evolution of fine grained structure and superplasticity of 7075 aluminum alloy

Cited by 47 publications

References 11 publications

The Role of Grain Boundary Sliding in Microstructural Evolution during Superplastic Deformation of a 7055 Aluminum Alloy

The Role of Grain Boundary Sliding in Microstructural Evolution during Superplastic Deformation of a 7055 Aluminum Alloy

Superplastic Behavior of a High-Strength Al-Zn-Mg-Cu-Zr Alloy

Effect of Zr Addition on Dynamic Recrystallization during Hot Extrusion in Al Alloys

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