On plastic flow in notched hexagonal close packed single crystals

On plastic flow in notched hexagonal close packed single crystals The micromechanics of anisotropic plastic flow by combined slip and twinning is investigated computationally in single crystal notched specimens. Constitutive relations for hexagonal close packed materials are used which take into account elastic anisotropy, thirty potential deformation systems, various hardening mechanisms and rate-sensitivity. The specimens are loaded perpendicular to the c-axis but the presence of a notch generates three-dimensional triaxial stress states. The study is motivated by recent experiments on a polycrystalline magnesium alloy. To enable comparisons with these where appropriate, three sets of activation thresholds for the various deformation systems are used. For the conditions that most closely mimic the alloy material, attention is focused on the relative roles of pyramidal ⟨c+a⟩ and prismatic ⟨a⟩ slip, as well as on the emergence of {1012¯}[101¯1] extension twinning at sufficiently high triaxiality. In all cases, the spatial variations of stress triaxiality and plastic strain, inclusive of various system activities, are quantified along with their evolution upon straining. The implications of these findings in fundamental understanding of ductile failure of HCP alloys in general and Mg alloys in particular are discussed. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of the Mechanics and Physics of Solids Elsevier

On plastic flow in notched hexagonal close packed single crystals

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Publisher
Elsevier
Copyright
Copyright © 2016 Elsevier Ltd
ISSN
0022-5096
eISSN
1873-4782
D.O.I.
10.1016/j.jmps.2016.04.023
Publisher site
See Article on Publisher Site

Abstract

The micromechanics of anisotropic plastic flow by combined slip and twinning is investigated computationally in single crystal notched specimens. Constitutive relations for hexagonal close packed materials are used which take into account elastic anisotropy, thirty potential deformation systems, various hardening mechanisms and rate-sensitivity. The specimens are loaded perpendicular to the c-axis but the presence of a notch generates three-dimensional triaxial stress states. The study is motivated by recent experiments on a polycrystalline magnesium alloy. To enable comparisons with these where appropriate, three sets of activation thresholds for the various deformation systems are used. For the conditions that most closely mimic the alloy material, attention is focused on the relative roles of pyramidal ⟨c+a⟩ and prismatic ⟨a⟩ slip, as well as on the emergence of {1012¯}[101¯1] extension twinning at sufficiently high triaxiality. In all cases, the spatial variations of stress triaxiality and plastic strain, inclusive of various system activities, are quantified along with their evolution upon straining. The implications of these findings in fundamental understanding of ductile failure of HCP alloys in general and Mg alloys in particular are discussed.

Journal

Journal of the Mechanics and Physics of SolidsElsevier

Published: Sep 1, 2016

References

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