Investigation of slip transfer across HCP grain boundaries with application to cold dwell facet fatigue

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Title: Investigation of slip transfer across HCP grain boundaries with application to cold dwell facet fatigue
Author(s): Zheng, Z
Balint, D
Dunne, F
Item Type: Journal Article
Abstract: This paper addresses the role of grain boundary slip transfer and thermally-activated discrete dislocation plasticity in the redistribution of grain boundary stresses during cold dwell fatigue in titanium alloys. Atomistic simulations have been utilised to calculate the grain boundary energies for titanium with respect to the misorientation angles. The grain boundary energies are utilised within a thermally-activated discrete dislocation plasticity model incorporating slip transfer controlled by energetic and grain boundary geometrical criteria. The model predicts the grain size effect on the flow strength in Ti alloys. Cold dwell fatigue behaviour in Ti-6242 alloy is investigated and it is shown that significant stress redistribution from soft to hard grains occurs during the stress dwell, which is observed both for grain boundaries for which slip transfer is permitted and inhibited. However, the grain boundary slip penetration is shown to lead to significantly higher hard-grain basal stresses near the grain boundary after dwell, thus exacerbating the load shedding stress compared to an impenetrable grain boundary. The key property controlling the dwell fatigue response is argued to remain the time constant associated with the thermal activation process for dislocation escape, but the slip penetrability is also important and exacerbates the load shedding. The inclusion of a macrozone does not significantly change the conclusions but does potentially lead to the possibility of a larger initial facet.
Publication Date: 11-Jan-2017
Date of Acceptance: 9-Jan-2017
URI: http://hdl.handle.net/10044/1/43886
DOI: https://dx.doi.org/10.1016/j.actamat.2017.01.021
ISSN: 1359-6454
Publisher: Elsevier
Start Page: 43
End Page: 53
Journal / Book Title: Acta Materialia
Volume: 127
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
EPSRC
Funder's Grant Number: EP/K034332/1
EP/K034332/1
Copyright Statement: © 2017 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Keywords: Materials
0912 Materials Engineering
0913 Mechanical Engineering
Publication Status: Published
Open Access location: http://www.sciencedirect.com/science/article/pii/S1359645417300319
Appears in Collections:Mechanical Engineering
Materials
Faculty of Natural Sciences



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