C. Sudha - Profile on Academia.edu (original) (raw)

Papers by C. Sudha

The present study is aimed to determine the efficacy of natrum muriaticum on ovary of female orna... more The present study is aimed to determine the efficacy of natrum muriaticum on ovary of female ornamental fishes like Goldfish, Rosy barb, White Molly and Guppy. The histological sections of ovaries show large number of oocytes in various stages of development. Based on changes in ovary, four oocyte stages have been recorded viz. primary oocyte stage, cortical alveolus stage, vitellogenic stage and mature oocyte stage. Depending upon the stages of oocytes in experimental animals it shows that natrum muriaticum has a greater influence in reproductive cycle. The study therefore suggested that natrum muriaticum has a significant effect on the ovaries and advances the breeding activity faster than the control fishes.

Friction welding of mild steel and titanium: Optimization of process parameters and evolution of interface microstructure

Materials & Design, 2015

Metallurgical and Materials Transactions A, 2015

Ti-5Ta-2Nb alloy was joined to 304L austenitic stainless steel by explosive cladding technique. E... more Ti-5Ta-2Nb alloy was joined to 304L austenitic stainless steel by explosive cladding technique. Explosive cladding resulted in the formation of deformation-induced martensite in 304L SS and fcc phase of Ti in the Ti-5Ta-2Nb side of the joint. The stability of these metastable phases was systematically studied using high-temperature X-ray diffraction technique and transmission electron microscopy, which enabled the optimization of the temperature window for post-cladding heat treatments.

Modification in the Microstructure of Mod. 9Cr-1Mo Ferritic Martensitic Steel Exposed to Sodium

Metallurgical and Materials Transactions A, 2014

ABSTRACT Mod. 9Cr-1Mo is used as the structural material in the steam generator circuit of liquid... more ABSTRACT Mod. 9Cr-1Mo is used as the structural material in the steam generator circuit of liquid metal-cooled fast breeder reactors. Microstructural modifications on the surface of this steel are investigated after exposing to flowing sodium at a temperature of 798 K (525 °C) for 16000 hours. Sodium exposure results in the carburization of the ferritic steel up to a depth of ~218 µm from the surface. Electron microprobe analysis revealed the existence of two separate zones with appreciable difference in microchemistry within the carburized layer. Differences in the type, morphology, volume fraction, and microchemistry of the carbides present in the two zones are investigated using analytical transmission electron microscopy. Formation of separate zones within the carburized layer is understood as a combined effect of leaching, diffusion of the alloying elements, and thermal aging. Chromium concentration on the surface in the α-phase suggested possible degradation in the corrosion resistance of the steel. Further, concentration-dependent diffusivities for carbon are determined in the base material and carburized zones using Hall’s and den Broeder’s methods, respectively. These are given as inputs for simulating the concentration profiles for carbon using numerical computation technique based on finite difference method. Predicted thickness of the carburized zone agrees reasonably well with that of experiment.

Assessment of Mechanical Property of Ti-5Ta-2Nb and 304L SS Explosive Clad and Correlation with Microstructure

Procedia Engineering, 2014

ABSTRACT Spent fuel reprocessing plants of FBRs require advanced structural materials for service... more ABSTRACT Spent fuel reprocessing plants of FBRs require advanced structural materials for service in aggressive conditions. Ti-5Ta-2Nb is a candidate structural material for electrolytic dissolver whereas 304L SS is used for rest of the plant. ‘Zero failure’ requirement for the process vessels necessitated the development of defect free explosive clad between Ti-5Ta-2Nb and 304L SS. The paper deals with the investigations carried out on the mechanical properties and microstructure of the explosive clads, and modification in microstructure on subsequent thermal exposure. The structural integrity of the clad as a consequence of these structure-property changes is also discussed in the paper.

Metal interlayers to prevent ‘hard zone’ formation in dissimilar weldments of Cr-Mo steels — A comparison between Cu, Co and Ni

Transactions of the Indian Institute of Metals, 2008

R Anand, C Sudha, T Karthikeyan, ALE Terrance, S Saroja, M Vijayalakshmi Transactions of the Indi... more R Anand, C Sudha, T Karthikeyan, ALE Terrance, S Saroja, M Vijayalakshmi Transactions of the Indian Institute of Metals 61:66, 483-486, Indian Institute of Metals, Metal House, Plot 13/4, Block AQ, Sector V, Salt Lake, Calcutta, 700 091, India,, 12/2008. ...

Evaluation of concentration dependant diffusion coefficients of carbon in a dissimilar joint of ferritic steels

Transactions of the Indian Institute of Metals, 2010

... Authors also thank Dr. KS Viswanathan and Shri. S. Sriram of Materials Chemistry Division for... more ... Authors also thank Dr. KS Viswanathan and Shri. S. Sriram of Materials Chemistry Division for their help in getting the carbon standards. References ... 4. Race JM and Bhadeshia HKDH, ibid, p 315. 5. Sudha C, Terrance ALE, Albert SK and Vijayalakshmi M, J. Nucl. ...

Microstructure and deformation mode of a stainless steel rupture disc exposed to sodium–water reaction

Materials Characterization, 2008

This paper deals with microstructural studies carried out on an austenitic stainless steel ruptur... more This paper deals with microstructural studies carried out on an austenitic stainless steel rupture disc which was exposed to sodiumwater reaction. The rupture disc was part of a leak simulator put in a micro leak test section which was used to study the 'self wastage'of ...

Hardfacing of a Modified 9Cr–1Mo Steel Component Using a Nickel-Base Alloy

Transactions of the Indian Institute of Metals, 2011

... H. Kumar (&) 4 SK Albert 4 C. Sudha 4 R. Vijayashree 4 AK Bhaduri Indira Gandhi Centre fo... more ... H. Kumar (&) 4 SK Albert 4 C. Sudha 4 R. Vijayashree 4 AK Bhaduri Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, India e-mail: hemant@igcar.gov.in ... 1. Bhaduri AK, Indira R, Albert SK, Rao BPS, Jain SC, and Asokkumar S, J Nucl Mater 334 (2004) 109. ...

Diffusion of Nitrogen in fcc-Fe and fcc-Ni Lattices: Molecular Dynamic Simulations

This paper presents the evaluation of bond strength and corrosion resistance in an explosive clad... more This paper presents the evaluation of bond strength and corrosion resistance in an explosive clad of Ti-5Ta-1.8Nb (Ti-Ta-Nb) and AISI type 304L austenitic stainless steel. Mechanical properties of the joints were evaluated using various techniques such as hardness measurement, tensile, shear and three point U-bend testing. High hardness obtained near the interface may lead to loss of ductility and debonding of the clad. Ultimate tensile strength of 304L stainless steel (304L SS) base plate was found to have increased to 894MPa due to large fraction of lattice defects and formation of deformation induced martensite. Tensile strength of Ti-Ta-Nb flyer plate remained the same after cladding. Fracture surfaces of both base and flyer plates showed only ductile mode of failure. Tensile testing of the clad showed high tensile strength of the order of 796MPa but de-bonding was observed right at the interface. Even though in three point U-bend testing an included angle of 110º was obtained, tearing was observed at the interface. Maximum and minimum shear strength values were obtained as 450MPa and 293MPa respectively. Further examination of the specimens after shear test gave indication for the presence of Fe and Ti base intermetallics in few regions. From these studies it can be concluded that in explosive welding, intermetallics are present as isolated pockets at the interface unlike in the case of fusion welds where they appear as continuous zones parallel to the interface. Post weld heat treatment of explosive clads between cp-Ti and 304L SS has been reported to improve the bond strength due to enhanced bonding and release of residual stresses. Corrosion rate of the clads was more in liquid phase than vapor and condensate phases. Severe intergranular corrosion of SS base plate was identified as the reason for higher corrosion rate exhibited by the clad in the liquid phase.

Direct evidence for enrichment of carbon in hard zone of dissimilar weldments of Cr-Mo steels

19.Transmission Electron Microscopy studies on an explosive welded dissimilar joint of stainless steel 304L and Ti -5Ta-1.8Nb alloy

Study on Microstructural Changes and Corrosion Resistance of Ti-5 Ta-2 Nb/304 L SS Explosive Clads in Concentrated Nitric Acid

Results in Physics, 2014

Please cite this article as: Prasanthi, T.N., Sudha, C., Saroja, S., Vijayalakshmi, M., Simulatio... more Please cite this article as: Prasanthi, T.N., Sudha, C., Saroja, S., Vijayalakshmi, M., Simulation of nitrogen diffusion in Ni vis-à-vis Fe -Identification of better structural material for neutron detectors, Results in Physics (2014), doi: http://dx.

Characterisation of nickel based hardfacing deposits on austenitic stainless steel

Surface Engineering, 2005

... Characterisation of nickel based hardfacing deposits on austenitic stainless steel CR Das 1 ,... more ... Characterisation of nickel based hardfacing deposits on austenitic stainless steel CR Das 1 , SK Albert 1 , AK Bhaduri* 1 , C. Sudha 2 and ALE Terrance 2 ... Figure 6 shows that both the blocky (Fig. 6a) and needle type (Fig. 6b) precipitates were rich in Cr and poor in Ni. ...

Surface and Coatings Technology, 2008

Ni-Cr-Si-B alloy coatings deposited on AISI 304L stainless steel substrate using plasma transferr... more Ni-Cr-Si-B alloy coatings deposited on AISI 304L stainless steel substrate using plasma transferred arc welding process were studied with respect to the microchemical and microstructural modifications that take place during the process. The coating was characterized for (1) interface integrity and dilution (2) type, morphology and distribution of secondary phases in the coating (3) elemental redistribution between substrate and coating and (4) different phases that form during the deposition process. Formation of a transition zone of only 760 μm width was understood in terms of interdiffusion of Fe and Ni across the interface. Preferential redistribution of carbon to the surface of the coating was observed. It was explained on the basis of difference in thermodynamic activity. Apart from γ-Ni solid solution, the other primary phases identified in Ni-Cr-Si-B alloy were Cr 2 B, Cr 7 C 3 and Cr 3 C 2 . The observed changes in microstructure, microchemistry and hardness have been understood based on the phase transitions of the Ni rich alloy during solidification and cooling on the substrate.

Nitriding Kinetics of Inconel 600

Surface and Coatings Technology, 2013

ABSTRACT Ni-based alloys are preferred as structural materials over austenitic stainless steels i... more ABSTRACT Ni-based alloys are preferred as structural materials over austenitic stainless steels in nitrogen containing atmospheres like in neutron detectors due to severe problem of nitriding of stainless steels and subsequent loss of nitrogen. Extensive work has been carried out in literature on the nitriding behavior of austenitic stainless steels whereas similar information on Ni-based alloys is very few. Hence, to assess the nitriding kinetics of a Ni-based alloy (Inconel 600) nitriding experiments were carried out. Inconel 600 was plasma nitrided at temperatures in the range of 450–600 °C for time durations of 1 to 24 h. Evolution of the microstructure and kinetics of nitrided layer formation and its growth were investigated using various experimental techniques like electron probe micro-analysis and electron microscopy. Nitriding at a temperature of 600 °C for 24 h resulted in the formation of a nitrided zone of ~ 14 μm thickness. Inconel 600 was found to get internally nitrided resulting in the formation of nano-meter sized fcc CrN precipitates in Cr depleted Ni–Fe based matrix phase. Diffusion coefficient and activation energy values for the diffusion of nitrogen in fcc Ni-based matrix were evaluated using the studies on kinetics of growth of nitrided layer. These values were compared with the available information in literature on other Ni–Cr–Fe alloys.

Metastable Phase Transformation in Ti-5Ta-2Nb Alloy and 304L Austenitic Stainless Steel under Explosive Cladding Conditions

Metallurgical and Materials Transactions A, 2012

ABSTRACT Ti-5Ta-2Nb alloy was clad on 304L austenitic stainless steel (SS) using the explosive cl... more ABSTRACT Ti-5Ta-2Nb alloy was clad on 304L austenitic stainless steel (SS) using the explosive cladding process. Both Ti-5Ta-2Nb and 304L austenitic steel were severely deformed due to high pressure (in the gigapascal range) and strain rate (105/s), which are characteristics of explosive loading conditions. Consequent changes produced in the microstructure and crystal structure of both the alloys are studied using electron microscopy techniques. The microstructure of both Ti-Ta-Nb alloy and 304L steel showed evidence for the passage of the shock waves in the form of a high number density of lattice defects such as dislocations and deformation twins. In addition, both the alloys showed signatures of phase transformation under nonequilibrium conditions resulting in metastable transformation products. 304L SS showed martensitic transformation to both α′(bcc) and ε(hcp) phases. Microscopic shear bands, shear band intersections, and twin boundaries were identified as nucleation sites for the formation of strain-induced phases. Ti-Ta-Nb alloy underwent metastable phase transformation to an fcc phase, which could be associated with regions having a specific morphology.

$Research paper thumbnail of A study on the thermal expansion characteristics of Inconel-82® filler wire by high temperature X-ray diffraction$

Materials Letters, 2004

The lattice parameter (a) change with respect to temperature (T) has been measured by high temper... more The lattice parameter (a) change with respect to temperature (T) has been measured by high temperature X-ray diffraction (HT-XRD) technique for Inconel-82R 1 filler wire used in the TIG welding of a dissimilar joint involving Inconel-600R and commercially pure iron. By taking proper precautions to minimise the temperature gradient across the sample thickness, and by suitably calibrating the shift in 2h produced as a result of sample buckling at high temperatures, we could obtain fairly reliable estimates of lattice parameter in the temperature range 300 -1200 K. The lattice parameter and the coefficient of mean linear thermal expansion at 300 K, have been found to be 3.546(2) Â 10 À 10 m and 11.03 Â 10 À 6 K À 1 , respectively.