Showing papers by "Bhagwati Prasad Kashyap published in 2004"
TL;DR: In this paper, the effect of reoriented hydrides on the tensile properties of the Zr-2.5 wt% Nb pressure tube alloy was evaluated in the temperature range of 298-573 K.
98 citations
TL;DR: In this article, a simple fracture criterion is proposed in terms of integrals of stress functions, taking into account the tensile stress ratio and triaxiality, and a simple and reliable procedure is also suggested to evaluate the material constants in the criterion.
37 citations
TL;DR: In this paper, the authors presented the X-ray diffraction peaks shape analysis and their broadening with different thermal treatments in Zr -2·5% Nb pressure tube material and the peak shape was analyzed using Fourier transformation and information about coherent domain size, micro-strain and dislocation density could be obtained from the Fourier coefficients of the peak.
Abstract: The microstructure characterization by X-ray line profile analysis is possible for determination of dislocation density, micro-strain within grains due to dislocation and average cohe rent domain size (sub- grain) within the grain. This study presents the X -ray diffraction peaks shape analysis and their broadening with different thermal treatments in Zr -2·5% Nb pressure tube material. The peak shape is analysed using Fourier transformation and information about coherent domain size, micro-strain and dislocation density could be obtained from the Fourier coefficients of the peak. Analysis of broadening of the peaks by integral breadth method also gives the coherent domain size, dislocation density and micro -strain present in the mate- rial. The results from the X-ray techniques are comparable to those obtained from direct observation of transmission electron microscopy. The measured yield strength increases with dislocation density. An empir i- cal relationship is obtained for the yield strength from the dislocation density of the material. The measured strength is in agreement with the one calculated from dislocation density.
35 citations
TL;DR: A simple instability condition is applied to delineate the regions of unstable metal flow in the processing map utilising flow stress data for AFNOR 7020 aluminium alloy, which was fitted in a constitutive equation as discussed by the authors.
Abstract: A simple instability condition is applied to delineate the regions of unstable metal flow in the processing map utilising flow stress data for AFNOR 7020 aluminium alloy, which was fitted in a constitutive equation Unstable regions identified from the simple instability condition at different strain levels were superimposed in the processing map This phenomenon takes into account the dependence of strain rate sensitivity and strain hardening effect on plastic instability during hot deformation of the material The processing map has been developed and validated by comparing microstructural observations of deformed compression specimens
24 citations
TL;DR: In this article, the texture evolution during fabrication of two-phase Zr-2.5 wt-%Nb was investigated using a modified route, and it was observed that a strong orientation fibre parallel to the working direction develops with hot working (extrusion). With subsequent cold working, the texture formed after extrusion alone becomes strengthened.
Abstract: Two phase Zr – 2.5 wt-%Nb is used as pressure tube material in water cooled and moderated reactors. The in service behaviour of this hcp zirconium based alloy is dependent on strong textures developed during thermomechanical processing. In the present study, the texture evolution during fabrication of this material, using a modified route, was investigated. Texture, evaluated by the orientation distribution function, was correlated to microstructure during various stages of processing. It was observed that a strong orientation fibre parallel to the working direction develops with hot working (extrusion). With subsequent cold working, the texture formed after extrusion alone becomes strengthened. This observation is attributed to the presence of a soft secondary phase (β) at the α-phase grain boundary. In contrast to the above, in the case of single phase Zircaloy 4, new components of texture are generated with cold deformation after hot extrusion, as a result of interaction between grains.
5 citations