Effect of Recrystallization on Hot Deformation Mechanism of TA15 Titanium Alloy under Uniaxial Tension and Biaxial Gas Bulging Conditions
File(s)
Author(s)
Wang, K
Liu, G
Huang, K
Politis
wang, LILIANG
Type
Journal Article
Abstract
To investigate the effect of recrystallization on hot deformation mechanism of TA15 titanium
alloy, rolled sheet and laser-welded tubes before and after recrystallization annealing were tested by
uniaxial tensile tests and biaxial gas bulging respectively. The results show that both of the initial rolled
sheet and the as-welded tube consisted of equiaxed α microstructure with high initial dislocation
density. During uniaxial tensile tests, a quasi-steady flow state was achieved at 800o C, 0.001 s-1
, which
demonstrated the best formability with a maximum elongation of 536%. Significant recrystallization
occurred at the early stage of tensile deformation and the grain size was found to decrease first and then
increase. Significant recrystallization also occurred at the early stage of the biaxial gas bulging of the
as-welded tube. During the bulging of the annealed tube consisting of equiaxed α with low initial
dislocation density, dynamic recrystallization (DRX) was the main microstructure evolution
characteristic, but most of the DRX occurred at the middle-late stage. The relatively coarse equiaxed α
and increasing fraction of low angle grain boundaries during deformation may restrict the occurrence
of grain boundary sliding (GBS), which resulted in the relatively worse formability of the annealed
tube. However, recrystallization which happened widely at the early stage, increased the fraction of
high angle grain boundaries, refined the microstructure, promoted the occurrence of GBS and enhanced
the formability of the initial rolled sheet and as-welded tube. It was also found that the stress state had
no effect on the DRX mechanism for TA15 at 800o C, which was confirmed to be discontinuous
dynamic recrystallization under both uniaxial tension and biaxial gas bulging conditions.
alloy, rolled sheet and laser-welded tubes before and after recrystallization annealing were tested by
uniaxial tensile tests and biaxial gas bulging respectively. The results show that both of the initial rolled
sheet and the as-welded tube consisted of equiaxed α microstructure with high initial dislocation
density. During uniaxial tensile tests, a quasi-steady flow state was achieved at 800o C, 0.001 s-1
, which
demonstrated the best formability with a maximum elongation of 536%. Significant recrystallization
occurred at the early stage of tensile deformation and the grain size was found to decrease first and then
increase. Significant recrystallization also occurred at the early stage of the biaxial gas bulging of the
as-welded tube. During the bulging of the annealed tube consisting of equiaxed α with low initial
dislocation density, dynamic recrystallization (DRX) was the main microstructure evolution
characteristic, but most of the DRX occurred at the middle-late stage. The relatively coarse equiaxed α
and increasing fraction of low angle grain boundaries during deformation may restrict the occurrence
of grain boundary sliding (GBS), which resulted in the relatively worse formability of the annealed
tube. However, recrystallization which happened widely at the early stage, increased the fraction of
high angle grain boundaries, refined the microstructure, promoted the occurrence of GBS and enhanced
the formability of the initial rolled sheet and as-welded tube. It was also found that the stress state had
no effect on the DRX mechanism for TA15 at 800o C, which was confirmed to be discontinuous
dynamic recrystallization under both uniaxial tension and biaxial gas bulging conditions.
Date Issued
2017-09-30
Date Acceptance
2017-09-29
Citation
Materials Science and Engineering: A, 2017, 708, pp.149-158
ISSN
0921-5093
Publisher
Elsevier
Start Page
149
End Page
158
Journal / Book Title
Materials Science and Engineering: A
Volume
708
Copyright Statement
© 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Subjects
0912 Materials Engineering
0913 Mechanical Engineering
Materials
Publication Status
Published
Date Publish Online
2017-09-30