A nanoindentation investigation of local strain rate sensitivity in dual-phase Ti alloys
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Published version
Accepted version
Author(s)
Jun, T
Armstrong, DEJ
Britton, TB
Type
Journal Article
Abstract
Using nanoindentation we have investigated the local strain rate sensitivity in dual-phase Ti alloys, Ti-6Al-2Sn-4Zr-xMo (x=2 and 6), as strain rate sensitivity could be a potential factor causing cold dwell fatigue. Electron backscatter diffraction (EBSD) was used to select hard and soft grain orientations within each of the alloys. Nanoindentation based tests using the continuous stiffness measurement (CSM) method were performed with variable strain rates, on the order of 10-1 to 10-3s-1. Local strain rate sensitivity is determined using a power law linking equivalent flow stress and equivalent plastic strain rate. Analysis of residual impressions using both a scanning electron microscope (SEM) and a focused ion beam (FIB) reveals local deformation around the indents and shows that nanoindentation tested structures containing both α and β phases within individual colonies. This indicates that the indentation results are derived from averaged α/β properties. The results show that a trend of local rate sensitivity in Ti6242 and Ti6246 is strikingly different; as similar rate sensitivities are found in Ti6246 regardless of grain orientation, whilst a grain orientation dependence is observed in Ti6242. These findings are important for understanding dwell fatigue deformation modes, and the methodology demonstrated can be used for screening new alloy designs and microstructures.
Date Issued
2016-02-19
Date Acceptance
2016-02-16
Citation
Journal of Alloys and Compounds, 2016, 672, pp.282-291
ISSN
1873-4669
Publisher
Elsevier
Start Page
282
End Page
291
Journal / Book Title
Journal of Alloys and Compounds
Volume
672
Copyright Statement
© 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/).
(http://creativecommons.org/licenses/by/4.0/).
License URL
Sponsor
Royal Academy Of Engineering
Grant Number
RF/129
Subjects
Materials
0912 Materials Engineering
0914 Resources Engineering And Extractive Metallurgy
0204 Condensed Matter Physics
Publication Status
Published