Direct Observations on Twinning: Split Channel Die Plane ...Email: [email protected] Direct...
Transcript of Direct Observations on Twinning: Split Channel Die Plane ...Email: [email protected] Direct...
RESEARCH POSTER PRESENTATION DESIGN © 2012
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INTRODUCTION
To capture microstructural dependency and orientation sensitivity of deformation
twinning.
OBJECTIVE
Support from Board of Research on Nuclear Science (BRNS) is acknowledged. The
authors also acknowledge support from the National Facility of Texture and OIM – a
DST-IRPHA facility at IIT Bombay.
CONCLUSIONS
IPF maps of Sample A (Hot extruded tube) (a) Undeformed (b) 4.3% Deformed (c) 10.6% Deformed (d)
15% Deformed and (e) 22% Deformed (inset shows the formation and growth of twin in a grain)
RESULTS AND DISCUSSION
REFERENCES
ACKNOWLEDGEMENTS
IPF maps of Sample B (Extruded and annealed tube) (a) Undeformed (b) 4.5% Deformed (c) 10.2% Deformed
(d) 15% Deformed and (e) 22% Deformed (inset shows the formation and growth of twin in a grain)
Jaiveer Singh1, I. Samajdar1, Prita Pant1, K.V. Mani2, D. Srivastava2, G. K. Dey2 and N. Saibaba3 1Department of Metallurgical Engineering & Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai-400 076, India
2Materials Science Division, Bhabha Atomic Research Centre, Mumbai-400 085, India 3Nuclear Fuel Complex, Hyderabad-500 062, India
Email: [email protected]
Direct Observations on Twinning: Split Channel Die Plane Strain Compression of Zircaloy 4
Zircaloy 4 (Zr 4) is used for making fuel cladding tubes used in nuclear reactors. Given
the critical nature of this application, it is important to understand the deformation
behavior of Zr 4. Deformation twinning in Zr 4 was observed through split channel
die plane strain compression (PSC). To capture microstructure sensitivity of
deformation twinning, the same microstructure was observed, through electron
backscattered diffraction (EBSD), after progressive deformation up to 20%. Two sets
of samples (A and B) were used. A had a typical hot extruded structure, while A
subjected to grain coarsening provided sample B. A had ~6 times deformation
twinning than B. A and B had similar basal texture. A had finer grain size (11 mm)
than B (18 mm). However the primary difference between A and B was in grain size
distribution: A having a clear bimodal distribution.
EXPERIMENTAL SET-UP
Schematic of a split channel compression die setup and sample with indent marks
(a) (b) (c)
(d) (e)
(a) (b)
(c) (d) (e)
(a) Grain size Distribution for Sample A and B (Samples A and B have average grain sizes of 11 µm and
18 µm respectively), (b) IPF and ODF sections (2 =30) for Samples A and B. Fraction of grains having:
(c) Basal orientation (d) Prismatic (1 01 0) orientation and (e) Prismatic (211 0) orientation
Twin Orientation Sensitivity
1. The extent of twinning in sample A is significantly higher than in sample B. In
sample A maximum twinning is at 10% deformation, followed by twin decay.
2. In sample A almost all orientations undergo twinning while in B twinning is limited
to prismatic orientations.
3. In sample A mostly finer grains (4 to 8 mm) underwent twinning, while in sample B
mostly larger grains (12 to 24 mm) twinned.
[1] N. Vanderesse, Ch. Desrayaud, S. G. Insardi, M. Darrieulat, Mater. Sci. Eng. A 476
(2008) 322. ACH
[2] R. J. McCabe, G. Proust, E. K. Cerreta, A. Misra, Int. J. Plast. 25 (2009) 454.
No. of twinned grains /
no. of total grains
Twin Area Fraction Fraction of twinned
grains
0
0.02
0.04
0.06
0.08
0.1
2.50% 4.50% 6.60% 10.60%
No
. of
Tw
inn
ed G
rain
s/ N
o.
of
To
tal G
rain
s
Strain
Sample A
Sample B
Avg. shear strain of sample A and B for twinned and untwinned grains
Twinned Untwinned
4.3% Def
10.6% Def
All Grains
(a) (b) (c)
(d) (e)
ND
RD