Strain rate sensitivity in commercial pure titanium: the competition between slip and deformation twinning
File(s)
Accepted version
Author(s)
Luan, Q
Britton, TB
Jun, T
Type
Journal Article
Abstract
Titanium alloys are widely used in light weight applications such as jet engine fans, where their mechanical performance under a range of loading regimes is important. Titanium alloys are mechanically anisotropic with respect to crystallographic orientation, and remarkably titanium creeps at room temperature. This means that the strain rate sensitivity (SRS) and stress relaxation performance are critical in predicting component life. In this work, we focus on systematically exploring the macroscopic SRS of Grade 1 commercially pure titanium (CP Ti) with varying grain sizes and texture using uniaxial compression. Briefly, we find that Ti samples had positive SRS and samples compressed along the sheet rolling direction (RD) (i.e. soft grains dominant) were less rate sensitive than bars compressed along the sheet normal direction (ND) (i.e. hard grains dominant). We attribute this rate sensitivity to the relative activity of slip and twinning. Within the grain size range of ~ 317 ±7 μm, we observe an increase in the rate sensitivity, where volume fraction of {101 ̅2}<101 ̅1> T1 tensile twins was low, and the twin width at different strain rates were similar. These observations imply that the macroscopic rate sensitivity is controlled by the ensemble behaviour of local deformation processes: the amount of slips accumulated at grain boundaries affects the SRS, which is grain size and texture dependent. We hope that this experimental study motivates mechanistic modelling studies using crystal plasticity, including strain rate sensitivity and twinning, to predict the performance of titanium alloys.
Date Issued
2018-09-12
Date Acceptance
2018-08-02
Citation
Materials Science and Engineering: A, 2018, 734, pp.385-397
ISSN
0921-5093
Publisher
Elsevier
Start Page
385
End Page
397
Journal / Book Title
Materials Science and Engineering: A
Volume
734
Copyright Statement
© 2018 Elsevier B.V. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Royal Academy Of Engineering
Grant Number
EP/K034332/1
RF/129
Subjects
0912 Materials Engineering
0913 Mechanical Engineering
Materials
Publication Status
Published
Date Publish Online
2018-08-07