Ultrafine Grain Formation in Ferritic Stainless Steel during Severe Plastic Deformation

Sakai, Taku; Belyakov, Andrey; Miura, Hiromi

doi:10.1007/s11661-008-9556-8

Cited by 122 publications

(73 citation statements)

References 31 publications

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“…1) Several SPD techniques such as equal channel angular pressing (ECAP), [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] torsion under high pressure 1,3,21) and multi-directional forging (MDF) [22][23][24][25][26][27][28] are now available for attaining of the UFG structures in numerous metals and alloys. There are several reports to date dealt with the investigation of the fine-grained structure evolution in Al alloys at different temperatures during SPD.…”

Section: Introductionmentioning

confidence: 99%

Partial Grain Refinement in Al-3%Cu Alloy during ECAP at Elevated Temperatures

et al. 2009

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Microstructural changes during equal channel angular pressing (ECAP) in a temperature interval from 523 to 748 K ($0:6{0:8 T m ) were studied in a coarse-grained binary aluminum alloy Al-3%Cu. Hot ECAP results in grain refinement taking place at all temperatures investigated, leading to a non-uniform development of deformation-induced fine grains and the remnant original grains containing subgrains with low-angle boundaries. Fine-grained structure is developed along microshear bands formed in grain interiors as well as along initial grain boundaries. The number and the average misorientation angle of the boundaries of microshear bands start to increase at above a critical strain of about 2, finally leading to development of new fine-grained structures. The volume fraction and the average misorientation of deformation-induced boundaries are reduced with rising temperature. The thermal stability of the evolved deformation microstructures and several factors controlling grain refinement during hot ECAP are discussed in details.

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Section: Introductionmentioning

confidence: 99%

Partial Grain Refinement in Al-3%Cu Alloy during ECAP at Elevated Temperatures

et al. 2009

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“…At Stage III, the number and misorientations of GNBs continuously increase with increasing cumulative strain, leading to the UFG development. Contrary to Stage I, the processes of UFG formation at Stages II and III are thermally activated ones [46,51]. Therefore, an increase in the MDF temperature accelerates the microstructural evolution.…”

Section: Ultrafine Grain Developmentmentioning

confidence: 99%

“…This transformation leads to the sub-division of the original grains into largely misoriented fragments. Sakai et al [46,51] considered this process to be a mechanically driven one. At Stage II, the sub-division of the deformation bands due to the transverse boundaries result in the development of a spatial array of GNBs.…”

Section: Ultrafine Grain Developmentmentioning

confidence: 99%

Grain refinement in a Cu–Cr–Zr alloy during multidirectional forging

Shakhova

Yanushkevich

Fedorova

et al. 2014

Materials Science and Engineering: A

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a b s t r a c tStructural changes during plastic deformation were studied in a Cu-0.3%Cr-0.5%Zr alloy subjected to multidirectional forging up to a total strain of 4 at the temperatures of 300 K and 673 K. The deformation behavior was characterized by a rapid increase in the flow stress at an early deformation followed by a steady-state flow at large strain. The development of the new ultrafine grains resulted from the progressive increase in the misorientations of the strain-induced low-angle boundaries, which evolve into high-angle boundaries with increasing cumulative strain through a strain-induced continuous reaction that is quite similar to continuous dynamic recrystallization. The formation of ultrafine grains was closely related to the development of geometrically necessary boundaries that is attributed to deformation banding. The grain refinement kinetics increased with an increase in the deformation temperature. At 673 K, the area fractions of the ultrafine grains with a size below 2 μm were 0.36 and 0.6 in the initially solution treated samples and the aged samples, respectively. However, the area fractions of the ultrafine grains did not exceed 0.2 at 300 K.

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“…Relationship between (a) the average misorientation of strain-induced (sub)boundaries (q av ) or (b) the fraction of strain-induced high-angle boundaries (HABs) (F HAB ) and the total strain during repeated MDF of Fe-20%Cr steel at 573K and 773K. 7) The data for an austenitic steel processed by MDF at 873K are included in (a). grain or subgrain sizes developed in large strain for pure copper deformed in a wide range of temperature.…”

Section: Kmentioning

confidence: 99%

Strain-Induced Grain Refinement and Its Mechanisms during Severe Multi-Directional Forging

Sakai¹,

Miura²

2008

Tetsu-to-Hagane

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The evolution processes of new high-angle boundaries as well as ultrafine grains processed by severe multidirectional forging (MDF) are studied in ferritic, austenitic steels and copper at low temperatures below 0.5T m (T m is the melting point), and aluminum and magnesium alloys at high temperatures above 0.5T m , where dynamic recovery operates mainly as a restoration process. The structural changes can be characterized by the evolution of deformation bands such as microshear or kink bands at moderate strains. MDF promotes the multiple shearing, which results in the formation of spatial net of mutually crossed bands subdividing the original grains. This is a mechanical induced event and so an athermal process. On the other hand, in large strain the fast operation of recovery processes accelerates the kinetics of ultrafine grain evolution with increasing temperature at low temperatures below 0.5T m . In contrast, the volume fraction of new grains decreases in large strain through hard development of deformation bands with increasing temperature at elevated temperatures above 0.5T m . The misorientations between (sub)grains evolved gradually increase with increase in strain, finally leading to the development of a new fine-grained structure. Temperature effect and the mechanism of strain-induced grain formation are discussed in detail. Key words : severe plastic deformation; microshear band; kink band, grain fragmentation; ultrafine grain; dynamic recrystallization; dynamic recovery; continuous and discontinuous reaction.

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Ultrafine Grain Formation in Ferritic Stainless Steel during Severe Plastic Deformation

Cited by 122 publications

References 31 publications

Partial Grain Refinement in Al-3%Cu Alloy during ECAP at Elevated Temperatures

Partial Grain Refinement in Al-3%Cu Alloy during ECAP at Elevated Temperatures

Grain refinement in a Cu–Cr–Zr alloy during multidirectional forging

Strain-Induced Grain Refinement and Its Mechanisms during Severe Multi-Directional Forging

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