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: jaiveer@iitb.ac.in

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