RESEARCH POSTER PRESENTATION DESIGN © 2012 www.PosterPresentations.com 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 Singh 1 , I. Samajdar 1 , Prita Pant 1 , K.V. Mani 2 , D. Srivastava 2 , G. K. Dey 2 and N. Saibaba 3 1 Department of Metallurgical Engineering & Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai-400 076, India 2 Materials Science Division, Bhabha Atomic Research Centre, Mumbai-400 085, India 3 Nuclear 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 Twinned Grains/ No. of Total Grains 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