Grain refinement in technically pure aluminium plates using incremental ECAP processing

W. Chrominski, L. Olejnik, A. Rosochowski, M. Lewandowska

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Ultrafine grained materials are capable of superplastic elongation at strain rates approximately two orders of magnitude faster than those currently employed for commercial superplastic forming operations. However, such operations require the material in the form of thin sheets. Therefore, in this work, a new approach to produce ultrafine grained plate samples using a modified equal channel angular pressing (ECAP) method, namely incremental ECAP, was proposed. Unlike conventional ECAP, incremental ECAP works in small steps in which deformation and feeding are associated with two different tools acting asynchronously. Eight passes were applied to technically pure aluminium, with the sample rotation by 90° around the Z axis, which resulted in two full rotations and accumulated strain equal to 9.2. It was demonstrated that grain refinement under these conditions occurs very efficiently. Eight passes resulted in grain size reduction to below 500 nm and very high fraction of high angle grain boundaries of about 80%. This was attributed to the activation of different slip systems in consecutive passes (thanks to sample rotation) and the lack of redundant strain, which results in early establishment of equiaxial grain structure. These two features confirm incremental ECAP to be one of the most effective severe plastic deformation methods in terms of grain size refinement and high angle grain boundaries formationreduction to below 500nm and very high fraction of high angle grain boundaries of about 80%. This was attributed to the activation of different slip systems in consecutive passes (thanks to sample rotation) and the lack of redundant strain, which results in early establishment of equiaxial grain structure. These two features confirm incremental ECAP to be one of the most effective severe plastic deformation methods in terms of grain size refinement and high angle grain boundaries formation.
LanguageEnglish
Pages172-180
Number of pages9
JournalMaterials Science and Engineering: A
Volume636
Early online date3 Apr 2015
DOIs
Publication statusPublished - 11 Jun 2015

Fingerprint

Equal channel angular pressing
Grain refinement
pressing
Aluminum
aluminum
Grain boundaries
grain boundaries
Processing
grain size
Crystal microstructure
plastic deformation
Plastic deformation
slip
Chemical activation
superplastic forming
activation
elongation
strain rate
Strain rate
Elongation

Keywords

  • aluminium
  • equal channel angular pressing
  • grain refinement
  • electron backscatter diffraction
  • transmission electron microscopy

Cite this

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title = "Grain refinement in technically pure aluminium plates using incremental ECAP processing",
abstract = "Ultrafine grained materials are capable of superplastic elongation at strain rates approximately two orders of magnitude faster than those currently employed for commercial superplastic forming operations. However, such operations require the material in the form of thin sheets. Therefore, in this work, a new approach to produce ultrafine grained plate samples using a modified equal channel angular pressing (ECAP) method, namely incremental ECAP, was proposed. Unlike conventional ECAP, incremental ECAP works in small steps in which deformation and feeding are associated with two different tools acting asynchronously. Eight passes were applied to technically pure aluminium, with the sample rotation by 90° around the Z axis, which resulted in two full rotations and accumulated strain equal to 9.2. It was demonstrated that grain refinement under these conditions occurs very efficiently. Eight passes resulted in grain size reduction to below 500 nm and very high fraction of high angle grain boundaries of about 80{\%}. This was attributed to the activation of different slip systems in consecutive passes (thanks to sample rotation) and the lack of redundant strain, which results in early establishment of equiaxial grain structure. These two features confirm incremental ECAP to be one of the most effective severe plastic deformation methods in terms of grain size refinement and high angle grain boundaries formationreduction to below 500nm and very high fraction of high angle grain boundaries of about 80{\%}. This was attributed to the activation of different slip systems in consecutive passes (thanks to sample rotation) and the lack of redundant strain, which results in early establishment of equiaxial grain structure. These two features confirm incremental ECAP to be one of the most effective severe plastic deformation methods in terms of grain size refinement and high angle grain boundaries formation.",
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author = "W. Chrominski and L. Olejnik and A. Rosochowski and M. Lewandowska",
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Grain refinement in technically pure aluminium plates using incremental ECAP processing. / Chrominski, W.; Olejnik, L.; Rosochowski, A.; Lewandowska, M.

In: Materials Science and Engineering: A, Vol. 636, 11.06.2015, p. 172-180.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Grain refinement in technically pure aluminium plates using incremental ECAP processing

AU - Chrominski, W.

AU - Olejnik, L.

AU - Rosochowski, A.

AU - Lewandowska, M.

PY - 2015/6/11

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N2 - Ultrafine grained materials are capable of superplastic elongation at strain rates approximately two orders of magnitude faster than those currently employed for commercial superplastic forming operations. However, such operations require the material in the form of thin sheets. Therefore, in this work, a new approach to produce ultrafine grained plate samples using a modified equal channel angular pressing (ECAP) method, namely incremental ECAP, was proposed. Unlike conventional ECAP, incremental ECAP works in small steps in which deformation and feeding are associated with two different tools acting asynchronously. Eight passes were applied to technically pure aluminium, with the sample rotation by 90° around the Z axis, which resulted in two full rotations and accumulated strain equal to 9.2. It was demonstrated that grain refinement under these conditions occurs very efficiently. Eight passes resulted in grain size reduction to below 500 nm and very high fraction of high angle grain boundaries of about 80%. This was attributed to the activation of different slip systems in consecutive passes (thanks to sample rotation) and the lack of redundant strain, which results in early establishment of equiaxial grain structure. These two features confirm incremental ECAP to be one of the most effective severe plastic deformation methods in terms of grain size refinement and high angle grain boundaries formationreduction to below 500nm and very high fraction of high angle grain boundaries of about 80%. This was attributed to the activation of different slip systems in consecutive passes (thanks to sample rotation) and the lack of redundant strain, which results in early establishment of equiaxial grain structure. These two features confirm incremental ECAP to be one of the most effective severe plastic deformation methods in terms of grain size refinement and high angle grain boundaries formation.

AB - Ultrafine grained materials are capable of superplastic elongation at strain rates approximately two orders of magnitude faster than those currently employed for commercial superplastic forming operations. However, such operations require the material in the form of thin sheets. Therefore, in this work, a new approach to produce ultrafine grained plate samples using a modified equal channel angular pressing (ECAP) method, namely incremental ECAP, was proposed. Unlike conventional ECAP, incremental ECAP works in small steps in which deformation and feeding are associated with two different tools acting asynchronously. Eight passes were applied to technically pure aluminium, with the sample rotation by 90° around the Z axis, which resulted in two full rotations and accumulated strain equal to 9.2. It was demonstrated that grain refinement under these conditions occurs very efficiently. Eight passes resulted in grain size reduction to below 500 nm and very high fraction of high angle grain boundaries of about 80%. This was attributed to the activation of different slip systems in consecutive passes (thanks to sample rotation) and the lack of redundant strain, which results in early establishment of equiaxial grain structure. These two features confirm incremental ECAP to be one of the most effective severe plastic deformation methods in terms of grain size refinement and high angle grain boundaries formationreduction to below 500nm and very high fraction of high angle grain boundaries of about 80%. This was attributed to the activation of different slip systems in consecutive passes (thanks to sample rotation) and the lack of redundant strain, which results in early establishment of equiaxial grain structure. These two features confirm incremental ECAP to be one of the most effective severe plastic deformation methods in terms of grain size refinement and high angle grain boundaries formation.

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KW - electron backscatter diffraction

KW - transmission electron microscopy

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JO - Materials Science and Engineering: A

T2 - Materials Science and Engineering: A

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SN - 0921-5093

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