Nuclear Fuel Complex Ltd

Hyderabad, India

Nuclear Fuel Complex Ltd

Hyderabad, India
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SAXENA K.K.,Indian Institute of Technology Roorkee | SAXENA K.K.,GLA University | JHA S.K.,Nuclear Fuel Complex Ltd | PANCHOLI V.,Indian Institute of Technology Roorkee | And 4 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2017

Dominant phase during hot deformation in the two-phase region of Zr–2.5Nb–0.5Cu (ZNC) alloy was studied using activation energy calculation of individual phases. Thermo-mechanical compression tests were performed on a two-phase ZNC alloy in the temperature range of 700–925 °C and strain rate range of 10−2–10 s−1. Flow stress data of the single phase were extrapolated in the two-phase range to calculate flow stress data of individual phases. Activation energies of individual phases were then calculated using calculated flow stress data in the two-phase range. Comparison of activation energies revealed that α phase is the dominant phase (deformation controlling phase) in the two-phase range. Constitutive equations were also developed on the basis of the deformation temperature range (or according to phases present) using a sine-hyperbolic type constitutive equation. The statistical analysis revealed that the constitutive equation developed for a particular phase showed good agreement with the experimental results in terms of correlation coefficient (R) and average absolute relative error (AARE). © 2017 The Nonferrous Metals Society of China


Fuloria D.,Indian Institute of Technology Roorkee | Kumar N.,Indian Institute of Technology Roorkee | Jayaganthan R.,Indian Institute of Technology Roorkee | Jayaganthan R.,Indian Institute of Technology Madras | And 2 more authors.
Materials Characterization | Year: 2017

In the present work, the effect of rolling at room (298 K) and cryogenic temperatures (77 K) on the microstructural and textural evolution of the as-received Zircaloy-4 bar along the planes parallel to the extrusion direction (ND - ED) and in the transverse direction (ND - TD) has been investigated. The as-received Zircaloy-4 was subjected to various rolling reductions of 25%, 50%, 70% and 90% which is corresponding to true strains of 0.29, 0.69, 1.2, and 2.3, respectively. A detailed analysis of microstructures and textures of the deformed alloy has been carried out through the electron backscattered diffraction (EBSD) and the XRD texture. Microstructures and textures of the samples rolled along the extrusion direction (ND - ED) at lower strains showed a few extension twinning (101−21−011) along with < a > prismatic slip at room temperature, and a combination of extension twinning, < a > prismatic, < c + a > pyramidal, and basal slips at cryogenic temperature. While along the transverse direction (ND - TD), at lower strains, extension twinning exhibited a dominant role at both the temperatures. This was eventually changed to slip dominant activity (< a > prismatic, < c + a > pyramidal and basal) from medium to high strains along both the directions (extrusion & transverse) at both the temperatures (RT & CT). © 2017


Saxena K.K.,Indian Institute of Technology Roorkee | Pancholi V.,Indian Institute of Technology Roorkee | Chaudhari G.P.,Indian Institute of Technology Roorkee | Srivastava D.,Bhabha Atomic Research Center | And 3 more authors.
Materials Science Forum | Year: 2017

In nuclear water reactors, zirconium alloys are extensively used as fuel cladding material and in other structural applications. Uniaxial hot compression tests were performed to understand the deformation behavior of Zr-1Nb alloy. Therefore, hot compression tests were performed in the temperature range of 700-1050°C, which envelopes α-phase, (α+β) phase, and β-phase. True stress-strain curves, processing maps, microstructural observation and kinetic analysis were used to discuss the deformation behavior of Zr-1Nb alloy. Deformation at a strain rate of 10-2s-1reveals softening at lower temperatures and steady state behavior at higher temperatures. Processing map also reveals domain of high efficiency at 10-2s-1strain rate for a wide range of deformation temperatures. The flow softening and high power dissipation efficiency predicts dynamic recrystallization or dynamic recovery during the hot deformation of studied alloy. © 2017 Trans Tech Publications, Switzerland.


Fuloria D.,Indian Institute of Technology Roorkee | Kumar N.,Indian Institute of Technology Roorkee | Jayaganthan R.,Indian Institute of Technology Roorkee | Jayaganthan R.,Indian Institute of Technology Madras | And 2 more authors.
Materials Characterization | Year: 2017

In the present work, the effect of various annealing temperatures on the microstructural and textural evolution in deformed Zircaloy-4 has been investigated. Zircaloy-4 was subjected to a rolling reduction of 90% corresponding to a true strain of 2.3 along the ND - ED and ND - TD planes of the as-received Zircaloy-4 bar at room (298 K) and cryogenic (77 K) temperatures. Following this, the various deformed conditions of the samples were subjected to annealing treatment at various temperatures such as 400°C, 450°C and 500°C. The deformed samples were characterized by a high dislocation density and nano scale subgrains, which after annealing at various temperatures were marked with annealing twins of nano - size along with some other dislocation configuration. A higher dislocation density and hardness (258.54 ± 2.91 HV) values were observed after annealing the cryorolled alloy along the ND - TD plane at 450°C. This high cold work energy provided by cryorolling along the ND - TD plane, after annealing at 450°C produced an optimum twin growth, which impeded the dislocation motion and slightly increased the hardness along this plane. Finally, the textures evolved after annealing indicated the role of annealing twins combined with < a > prismatic, < c + a > pyramidal & basal glide activity. © 2017 Elsevier Inc.


Fuloria D.,Indian Institute of Technology Roorkee | Goel S.,Indian Institute of Technology Roorkee | Jayaganthan R.,Indian Institute of Technology Roorkee | Srivastava D.,Bhabha Atomic Research Center | And 2 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2015

The mechanical properties and microstructural evolution of zircaloy-4 subjected to cumulative strains of 1.48, 2.96, 4.44 and 5.91 through multiaxial forging (MAF) at cryogenic temperature (77 K) were investigated. The mechanical properties of the MAF treated alloy were measured through universal tensile testing and Vickers hardness testing equipment. The zircaloy-4 deformed up to a cumulative strain of 5.91 showed improvement in both ultimate tensile strength and hardness from 474 MPa to 717 MPa and from HV 190 to HV 238, respectively, as compared with the as-received alloy. However, there was a noticeable decrement in ductility (from 18% to 3.5%) due to the low strain hardening ability of deformed zircaloy-4. The improvement in strength and hardness of the deformed alloy is attributed to the grain size effect and higher dislocation density generated during multiaxial forging. The microstructural evolutions of deformed samples were characterized by optical microscopy and transmission electron microscopy (TEM). The evolved microstructure at a cumulative strain of 5.91 obtained after MAF up to 12 cycles depicted the formation of ultrafine grains with an average size of 150-250 nm. © 2015 The Nonferrous Metals Society of China.


Fuloria D.,Indian Institute of Technology Roorkee | Kumar N.,Indian Institute of Technology Roorkee | Goel S.,Indian Institute of Technology Roorkee | Jayaganthan R.,Indian Institute of Technology Roorkee | And 3 more authors.
Materials and Design | Year: 2016

The effect of rolling at different temperatures and deformation strains on the variation in hardness and tensile properties of Zircaloy-4 has been investigated in the present work. The initial hot extruded and annealed Zircaloy-4 was subjected to various rolling reductions of 25%, 50%, 70%, and 90% at room (298 K) and liquid nitrogen (77 K) temperatures along extrusion and transverse directions of the as-received bar, respectively. The hardness and ultimate tensile strength (UTS) obtained for samples rolled to a true strain of 2.3 along the extrusion direction were 264.67 ± 3.8 HV, 786 MPa at 298 K, and 273.57 ± 1.6 HV, 856 MPa at 77 K, while along the transverse direction, the hardness and UTS values observed were 262.7 ± 3.77 HV, 727 MPa at 298 K, and 266.57 ± 2.7 HV, 827.63 MPa at 77 K. The enhancement in strength and hardness of the Zr alloy is attributed to increase in the stacking fault probability (SFP) with the applied progressive true strains at different temperatures, which led to the greater accumulation of dislocation density and hence a better grain refinement. © 2016 Elsevier Ltd.


Saxena K.K.,Indian Institute of Technology Roorkee | Pancholi V.,Indian Institute of Technology Roorkee | Srivastava D.,Bhabha Atomic Research Center | Dey G.K.,Bhabha Atomic Research Center | And 2 more authors.
Materials Science Forum | Year: 2015

Hot workability of Zr-2.5Nb-0.5Cu alloy has been investigated by means of hot compression test using Gleeble-3800®, in the temperature and strain rate range of 700 to 925°C and 0.01 -10s-1, respectively. Deformation behavior was characterized in terms of flow instability using peak stress with the help of Lyapunov Function. The true stress- strain curves shows that softening occurs at all lower temperature and for entire strain rates of deformation. The instable flow was suggested by negative m value at deformation condition of 700°C (5 and 10 s-1), while s value at 925°C (10 s-1). The combined result of rate of change of m and s with respect to log strain rate suggest that the deformation condition ranges from 725- 780°C (10-1- 10-1 s-1) and 700°C (1- 10 s-1) representing safe domain for stable flow. © (2015) Trans Tech Publications, Switzerland.


Goel S.,Indian Institute of Technology Roorkee | Jayaganthan R.,Indian Institute of Technology Roorkee | Singh I.V.,Indian Institute of Technology Roorkee | Srivastava D.,Bhabha Atomic Research Center | And 2 more authors.
Materials and Design | Year: 2014

The effect of deformation strain at room temperature on the microstructural and mechanical properties of Zircaloy-2 was investigated in the present work. The sample was initially heat treated at 800. °C in argon environment and quenched in mercury prior to rolling. The deformed alloys were characterized by using EBSD and TEM. It reveals the misorientation of incidental grain boundaries (IDBs) due to large plastic strain induced in the sample. The recovery of deformed alloy upon annealing leads to the formation of ultrafine and nanostructured grains in the alloy. The hardness achieved after 85% room temperature rolling (RTR) is found to be 269. HV, while the tensile strength is 679. MPa and 697. MPa in the rolling and transverse direction, respectively. The improvement in strength is due to generation of high dislocation density and ultrafine grains in the deformed alloy with 85% thickness reduction, during rolling. The deformed alloy subjected to annealing at 400. °C for 30. min sample shows increase in ductility (6% and 7.2%) in rolling and transverse direction, respectively, due to the annihilation of dislocations as evident from the TEM study. © 2013 Elsevier Ltd.


Goel S.,Indian Institute of Technology Roorkee | Keskar N.,Bhabha Atomic Research Center | Jayaganthan R.,Indian Institute of Technology Roorkee | Singh I.V.,Indian Institute of Technology Roorkee | And 3 more authors.
Materials Science and Engineering A | Year: 2014

The mechanical properties and microstructural characteristics of ultrafine grained Zircaloy-2 processed by cryorolling (CR) were investigated in the present work. The solutionised Zircaloy-2 was rolled at liquid nitrogen temperature (77. K) with different thickness reductions (25-85%). The dislocation density 〈. ρ〉 in the cryorolled Zircaloy-2 increases with increasing true strain due to the suppression of dynamic recovery. EBSD analysis of CR Zircaloy-2 revealed initial strain hardening, which has occurred due to activation of {101-2}〈1-011〉 tensile and {112-2}〈1-1-23〉 compressive twins during deformation of samples up to 50% strain. The prismatic and basal slips were activated during subsequent deformation. The fraction of low angle boundaries has increased with increasing true strain up to 50% thickness reduction but the fraction of high angle grain boundaries has increased for CR85% alloy. The CR 85% alloy showed hardness and yield strength values of 282 HV and 891. MPa, respectively. The annealed CR 85% alloy showed higher ductility (9.5% and 11.2% in rolling and transverse direction, respectively) as compared to CR 85% alloy. The annealed Zircaloy-2 showed heterogeneous microstructure consisting of ultrafine grains and nanograins. © 2014 Elsevier B.V.


Fuloria D.,Indian Institute of Technology Roorkee | Nageswararao P.,Indian Institute of Technology Roorkee | Jayaganthan R.,Indian Institute of Technology Roorkee | Jayaganthan R.,Indian Institute of Technology Madras | And 2 more authors.
Materials Chemistry and Physics | Year: 2016

In the present work, the mechanical behavior of Zircaloy-4 subjected to various deformation strains by multiaxial forging (MAF) at cryogenic temperature (CT) was investigated. The alloy was strained up to different number of cycles, viz., 6 cycles, 9 cycles, and 12 cycles at cumulative strains of 2.96, 4.44, and 5.91, respectively. The mechanical properties of the alloy were investigated by performing the universal tensile test and the Vickers hardness test. Both the test showed improvement in the ultimate tensile strength and hardness value by 51% and 26%, respectively, at the highest cumulative strain of 5.91. The electron backscattered diffraction (EBSD) measurement and transmission electron microscopy (TEM) were used for analyzing the deformed microstructure. The microstructures of the alloy underwent deformation at various cumulative strains/cycles showed grain refinement with the evolution of shear and twin bands that were highest for the alloy deformed at the highest number of cycles. The effective grain refinement was due to twins formation and their intersection, which led to the improvement in mechanical properties of the MAFed alloy, as observed in the present work. © 2015 Elsevier B.V.

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