Strain localization and failure in irradiated zircaloy with crystal plasticity
File(s)
Accepted version
Author(s)
Erinosho, TO
Dunne, FPE
Type
Journal Article
Abstract
This paper presents a micromechanical and mechanistic study of irradiation-induced crystallographic softening known to accelerate failure in irradiated zircaloys typically used as cladding material in pressure water nuclear reactors. The irradiation is known to lead to an increase in yield strength, and reduced ductility is anticipated to result from the progressive reduction in slip system strength. Extensive studies using transmission electron microscopy (TEM) show the formation of <a> type dislocation channels in irradiated zircaloys anticipated to affect basal and prismatic systems. A crystal plasticity approach is established to incorporate basal and prismatic crystallographic softening, both of which are shown to be required in order to capture independent experimental observations for irradiated zircaloy.
Representative irradiated zircaloy textures subjected to cyclic loading regimes were modelled to provide an understanding of the failure processes during in-service conditions. Under both strain and stress-controlled cyclic loading, irradiation softening led to the development of strain localization, and the formation of slip banding and its coalescence. This was found to lead to localized ratcheting and macroscale softening, and in strain-controlled loading, ultimately to plastic shakedown. Stress-controlled cyclic loading, however, especially with non-zero mean applied stress, led to pronounced local and macroscale ratcheting, influenced profoundly by the irradiation softening, and hence finally to ductile failure. It was also observed that local strain hardening due to GND development was small compared to irradiation-induced softening processes, supporting the notion that slip system softening dominates shear band formation.
Representative irradiated zircaloy textures subjected to cyclic loading regimes were modelled to provide an understanding of the failure processes during in-service conditions. Under both strain and stress-controlled cyclic loading, irradiation softening led to the development of strain localization, and the formation of slip banding and its coalescence. This was found to lead to localized ratcheting and macroscale softening, and in strain-controlled loading, ultimately to plastic shakedown. Stress-controlled cyclic loading, however, especially with non-zero mean applied stress, led to pronounced local and macroscale ratcheting, influenced profoundly by the irradiation softening, and hence finally to ductile failure. It was also observed that local strain hardening due to GND development was small compared to irradiation-induced softening processes, supporting the notion that slip system softening dominates shear band formation.
Date Issued
2015-05-21
Date Acceptance
2015-03-31
Citation
International Journal of Plasticity, 2015, 71, pp.170-194
ISSN
1879-2154
Publisher
Elsevier
Start Page
170
End Page
194
Journal / Book Title
International Journal of Plasticity
Volume
71
Copyright Statement
© 2015, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Subjects
Science & Technology
Technology
Engineering, Mechanical
Materials Science, Multidisciplinary
Mechanics
Engineering
Materials Science
Crystal plasticity
Cyclic loading
Dislocations
Finite elements
Zircaloy
CHANNEL DIE COMPRESSION
ZIRCONIUM ALLOYS
GLIDING DISLOCATIONS
ROOM-TEMPERATURE
PRISMATIC LOOPS
DEFORMATION
BEHAVIOR
SIMULATIONS
Publication Status
Published