A triple-scale dislocation-crystal plasticity simulation on yield point drop of annealed FCC ultrafine-grained metal

Eisuke Kurosawa, Yoshiteru Aoyagi, Kazuyuki Shizawa

Research output: Contribution to journalArticle

Abstract

Annealed ultrafine-grained metals contain some grains with extremely low dislocation density, so that the critical resolved shear stress increases at the first stage of deformation due to the exhaustion of dislocation sources in a grain. In this paper, in order to express the increase of critical resolved shear stress, the conventional Bailey-Hirsh's relationship is extended on the basis of physical consideration for grain boundary that plays a role of dislocation source. A triple-scale dislocation-crystal plasticity FE simulation based on the above model, geometrically necessary crystal defects and the homogenization method is carried out for annealed FCC polycrystals with different initial grain size and initial dislocation density. Yield point drop and propagation of Lüders bands observed in macroscopic specimen with annealed FCC fine-grains are numerically reproduced. Moreover, macroscopic yielding of specimen and microscopic grain yielding are investigated in detail so as to clarify the initial yield behavior of annealed ultrafine-grained metals. It is also shown that plastic deformation is easy to be localized and the tensile ductility decreases as the grain size reduces.

Original languageEnglish
Pages (from-to)1547-1556
Number of pages10
JournalNihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A
Volume76
Issue number772
Publication statusPublished - 2010 Dec

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Dislocations (crystals)
Plasticity
Metals
Shear stress
Homogenization method
Crystal defects
Polycrystals
Ductility
Plastic deformation
Grain boundaries
Ultrafine

Keywords

  • Crystal plasticity
  • Dislocation
  • Finite element method
  • Geometrically necessary dislocation
  • Homogenization method
  • Lüders band
  • Plasticity
  • Ultrafine-Grained metal
  • Yield point drop

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Materials Science(all)

Cite this

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abstract = "Annealed ultrafine-grained metals contain some grains with extremely low dislocation density, so that the critical resolved shear stress increases at the first stage of deformation due to the exhaustion of dislocation sources in a grain. In this paper, in order to express the increase of critical resolved shear stress, the conventional Bailey-Hirsh's relationship is extended on the basis of physical consideration for grain boundary that plays a role of dislocation source. A triple-scale dislocation-crystal plasticity FE simulation based on the above model, geometrically necessary crystal defects and the homogenization method is carried out for annealed FCC polycrystals with different initial grain size and initial dislocation density. Yield point drop and propagation of L{\"u}ders bands observed in macroscopic specimen with annealed FCC fine-grains are numerically reproduced. Moreover, macroscopic yielding of specimen and microscopic grain yielding are investigated in detail so as to clarify the initial yield behavior of annealed ultrafine-grained metals. It is also shown that plastic deformation is easy to be localized and the tensile ductility decreases as the grain size reduces.",
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AU - Aoyagi, Yoshiteru

AU - Shizawa, Kazuyuki

PY - 2010/12

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N2 - Annealed ultrafine-grained metals contain some grains with extremely low dislocation density, so that the critical resolved shear stress increases at the first stage of deformation due to the exhaustion of dislocation sources in a grain. In this paper, in order to express the increase of critical resolved shear stress, the conventional Bailey-Hirsh's relationship is extended on the basis of physical consideration for grain boundary that plays a role of dislocation source. A triple-scale dislocation-crystal plasticity FE simulation based on the above model, geometrically necessary crystal defects and the homogenization method is carried out for annealed FCC polycrystals with different initial grain size and initial dislocation density. Yield point drop and propagation of Lüders bands observed in macroscopic specimen with annealed FCC fine-grains are numerically reproduced. Moreover, macroscopic yielding of specimen and microscopic grain yielding are investigated in detail so as to clarify the initial yield behavior of annealed ultrafine-grained metals. It is also shown that plastic deformation is easy to be localized and the tensile ductility decreases as the grain size reduces.

AB - Annealed ultrafine-grained metals contain some grains with extremely low dislocation density, so that the critical resolved shear stress increases at the first stage of deformation due to the exhaustion of dislocation sources in a grain. In this paper, in order to express the increase of critical resolved shear stress, the conventional Bailey-Hirsh's relationship is extended on the basis of physical consideration for grain boundary that plays a role of dislocation source. A triple-scale dislocation-crystal plasticity FE simulation based on the above model, geometrically necessary crystal defects and the homogenization method is carried out for annealed FCC polycrystals with different initial grain size and initial dislocation density. Yield point drop and propagation of Lüders bands observed in macroscopic specimen with annealed FCC fine-grains are numerically reproduced. Moreover, macroscopic yielding of specimen and microscopic grain yielding are investigated in detail so as to clarify the initial yield behavior of annealed ultrafine-grained metals. It is also shown that plastic deformation is easy to be localized and the tensile ductility decreases as the grain size reduces.

KW - Crystal plasticity

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KW - Finite element method

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KW - Plasticity

KW - Ultrafine-Grained metal

KW - Yield point drop

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