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Miniature tensile testing of SPD processed fine-grained aluminum

Harishchandra Lanjewar (UGent) , Soroosh Naghdy (UGent) , Leo Kestens (UGent) and Patricia Verleysen (UGent)
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Abstract
Manufacturing of ultrafine-grained (UFG) or nanocrystalline (NC) metals via a single step top-down approach imposing severe plastic deformation (SPD) is one of the most promising ways to achieve superior properties such as high strength and superplastic forming capability. Nonetheless, the lack of relevant data on their post-SPD performance in different test environments makes it difficult to fully understand their mechanical behavior. While characterizing the tensile behavior, almost all of the previous reports are limited to the discussion on the plastic performance of the material in terms of elongation to failure and corresponding strength, with only a few studies discussing the effect of grain fragmentation on work hardening response of the material. In the present work, a comprehensive analysis is presented in terms of the uniform and post-necking mechanical behavior of the ultrafinegrained material. Commercially pure aluminum is subjected to high pressure torsion (HPT) deformation with strains ranging from very low levels (γ ≈ 2.1) to values well in the saturation regime (γ ≈ 25.1). When tested in uniaxial tension, the strength increases monotonously. The uniform elongation improves with the imposed HPT strain, though remains lower than the value of the initial material. Based on the slopes of the stress-strain curve, three distinct zones are identified, i.e. uniform deformation, post-necking-1, and post-necking-2. With accumulating SPD deformation, the material shows enhanced pre-necking strength and ductility; while post-necking material fails early and at lower strength levels. The post-necking response is observed to be highly microstructure dependent: a lower grain size augments the resistance for micro-crack propagation and thus the ductility, however, once initiated, a crack propagates much faster in fine-grained than in coarse-grained HPT processed material.

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MLA
Lanjewar, Harishchandra, et al. “Miniature Tensile Testing of SPD Processed Fine-Grained Aluminum.” JOURNAL OF PHYSICS CONFERENCE SERIES, vol. 1270, IOP, 2019, doi:10.1088/1742-6596/1270/1/012022.
APA
Lanjewar, H., Naghdy, S., Kestens, L., & Verleysen, P. (2019). Miniature tensile testing of SPD processed fine-grained aluminum. JOURNAL OF PHYSICS CONFERENCE SERIES, 1270. https://doi.org/10.1088/1742-6596/1270/1/012022
Chicago author-date
Lanjewar, Harishchandra, Soroosh Naghdy, Leo Kestens, and Patricia Verleysen. 2019. “Miniature Tensile Testing of SPD Processed Fine-Grained Aluminum.” In JOURNAL OF PHYSICS CONFERENCE SERIES. Vol. 1270. IOP. https://doi.org/10.1088/1742-6596/1270/1/012022.
Chicago author-date (all authors)
Lanjewar, Harishchandra, Soroosh Naghdy, Leo Kestens, and Patricia Verleysen. 2019. “Miniature Tensile Testing of SPD Processed Fine-Grained Aluminum.” In JOURNAL OF PHYSICS CONFERENCE SERIES. Vol. 1270. IOP. doi:10.1088/1742-6596/1270/1/012022.
Vancouver
1.
Lanjewar H, Naghdy S, Kestens L, Verleysen P. Miniature tensile testing of SPD processed fine-grained aluminum. In: JOURNAL OF PHYSICS CONFERENCE SERIES. IOP; 2019.
IEEE
[1]
H. Lanjewar, S. Naghdy, L. Kestens, and P. Verleysen, “Miniature tensile testing of SPD processed fine-grained aluminum,” in JOURNAL OF PHYSICS CONFERENCE SERIES, Ghent, 2019, vol. 1270.
@inproceedings{8626211,
  abstract     = {{Manufacturing of ultrafine-grained (UFG) or nanocrystalline (NC) metals via a
single step top-down approach imposing severe plastic deformation (SPD) is one of the most
promising ways to achieve superior properties such as high strength and superplastic forming
capability. Nonetheless, the lack of relevant data on their post-SPD performance in different
test environments makes it difficult to fully understand their mechanical behavior. While
characterizing the tensile behavior, almost all of the previous reports are limited to the
discussion on the plastic performance of the material in terms of elongation to failure and
corresponding strength, with only a few studies discussing the effect of grain fragmentation on
work hardening response of the material. In the present work, a comprehensive analysis is
presented in terms of the uniform and post-necking mechanical behavior of the ultrafinegrained material. Commercially pure aluminum is subjected to high pressure torsion (HPT)
deformation with strains ranging from very low levels (γ ≈ 2.1) to values well in the saturation
regime (γ ≈ 25.1). When tested in uniaxial tension, the strength increases monotonously. The
uniform elongation improves with the imposed HPT strain, though remains lower than the
value of the initial material. Based on the slopes of the stress-strain curve, three distinct zones
are identified, i.e. uniform deformation, post-necking-1, and post-necking-2. With
accumulating SPD deformation, the material shows enhanced pre-necking strength and
ductility; while post-necking material fails early and at lower strength levels. The post-necking
response is observed to be highly microstructure dependent: a lower grain size augments the
resistance for micro-crack propagation and thus the ductility, however, once initiated, a crack
propagates much faster in fine-grained than in coarse-grained HPT processed material.}},
  articleno    = {{012022}},
  author       = {{Lanjewar, Harishchandra and Naghdy, Soroosh and Kestens, Leo and Verleysen, Patricia}},
  booktitle    = {{JOURNAL OF PHYSICS CONFERENCE SERIES}},
  issn         = {{1742-6596}},
  language     = {{eng}},
  location     = {{Ghent}},
  pages        = {{6}},
  publisher    = {{IOP}},
  title        = {{Miniature tensile testing of SPD processed fine-grained aluminum}},
  url          = {{http://doi.org/10.1088/1742-6596/1270/1/012022}},
  volume       = {{1270}},
  year         = {{2019}},
}

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