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T. Jayakumar , M. Ilayaraja , M. P. Sridhar , S. Sivalokanathan , T. R. Bharth Prasad , M. P. Balasubramanian

Abstract

The present investigation was carried out to evaluate the lipid peroxidation and antioxidant nature of aqueous extract of Adhatoda vasica (AEAV) on D-galactosamine (D-GalN) induced hepatic damage in wistar albino rats. Hepatic damage was induced by intraperitonial injection of DGalN (500 mg/kg, bw) for 2 days. AEAV extract (350 mg/kg, bw) was given orally for 21 days before the induction of hepatic damage. The levels of lipid peroxides (LPO) under basal and also in the presence of inducers (H₂O₂, ascorbate and FeSO4) were estimated in liver of control and experimental animals. enzymic such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and non-enzymic antioxidants like glutathione (GSH), vitamin C (vit C) and vitamin E (vit E) and total thiols (TSH) levels were determined in all the groups of animals. A significant increase in LPO levels were observed while the levels of enzymic and non-enzymic antioxidant were decreased, in D-GalN induced rats. These altered enzyme levels were ameliorated significantly in AEAV pretreated animals. This protective effect of AEAV was associated with inhibition of LPO induced by D-GalN and to maintain the antioxidant enzyme levels. From this study it is concluded that the pre-treatment of AEAV has an antioxidant activity against D-GalN induced hepatic damage.

Keywords

D-galactosamine, Adhatoda Vasica, Lipid Peroxidation, Antioxidants Enzymes, Liver Damage

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G. Srinivasan ¹, H. C. Dey ¹, A. K. Bhaduri ¹, S. K. Albert ¹, T. Jayakumar ¹

Affiliations
1 Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, IN

Abstract

India has embarked on a mission program for setting-up a coal-fired 800 MWe Advanced Ultra Super Critical (AUSC) power plant with steam parameters of 710°C/ 720°C temperature 310 kg/cm² pressure. For the boiler tubes in the final stages of the superheater and reheater, the material chosen is 304HCu stainless steel (SS), a 18Cr-9Ni-3Cu-Nb-N austenitic SS (UNS S30432) as ASME code case 2328 and VdTUV 510 specifications. The 304HCu SS is a variant of the conventional 18Cr-8Ni austenitic SS, containing ~3% copper, increased carbon and controlled amounts of niobium and nitrogen, for enhanced elevated temperature strength, especially creep. India-specific version of 304HCu SS boiler tubes, of 52 mm diameter with 9.5 mm wall thickness, produced in collaboration with Indian manufacturers has been used for welding procedure qualification trials.

The objective of the present study is to choose the appropriate gas tungsten arc (GTA) welding consumable, from among ER304HCu (matching chemistry) and ERNiCrMo-3 and ERNiCrCoMo-1 (both nickel-base) filler wires, for welding of 304HCu SS. This involved qualifying the welding consumables, development of welding procedures for 304HCu SS tubes, and producing weld coupons for evaluation of mechanical properties and microstructural characterisation. Mock-up tube weld joints, with single-V groove joint geometry, were prepared using all the three filler wires to optimize the welding parameters. Weld defects like ischolar_main crack; hot crack and crater cracks were observed during the initial trials in weld joints made with the nickel-base filler metals due to the poor fluidity of the weld metal. These problems were overcome by suitably altering the weld joint design and optimisation of heat input. Subsequently, the weld joints were qualified, in the as-welded condition, by liquid penetrant and radiography examinations followed by tensile tests and bend tests as per ASME section IX requirements for preparing the Welding Procedure Qualification records. Based on detailed evaluation of mechanical properties, including creep, ER304HCu filler metal was chosen for welding of ER304HCuSS.

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P. Palanichamy ¹, A. Joseph ¹, Sanjai Rai ¹, T. Jayakumar ¹, D. K. Bhattacharya ¹, K. V. Kasiviswanathan ¹

Affiliations
1 Indira Gandhi Centre for Atomic Research, Kalpakkam, IN

Abstract

The knowledge of the nature and magnitudes of residual stress (RS.) in a weld joint is important for avoiding distortions and premature failures. Both analytical and experimental techniques are used for getting information on RS distributions.

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T. Jayakumar ¹, Anish Kumar ¹

Affiliations
1 Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, IN

Abstract

The paper presents various studies carried out in the authors' laboratory for multi-scale microstructural characterization in different metallic structural materials such as nickel base alloys, zirconium alloys and titanium alloys through elastic properties. The elastic properties are evaluated at macroscale using ultrasonic velocity measurements and at micro/nano scale using atomic force acoustic microscopy. A thickness independent ultrasonic measurement based nondestructive methodology implemented for in-situ assessment of degradation of alloy 625 ammonia cracker tubes in heavy water plants is also discussed.

Keywords

Elastic Property, Ultrasonic Velocity, Atomic Force Acoustic Microscopy, Microstructure.

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Giridhar Mishra ¹, R. R. Yadav ¹, Baldev Raj ², T. Jayakumar ²

Affiliations
1 Physics Department, University of Allahabad, Allahabad-211002, IN
2 Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, IN

Abstract

The single crystal higher order elastic constants of Ni-Al-Cr ternary alloy at different temperatures have been calculated with the help of interaction potential model. Ultrasonic attenuation in the ternary alloy is determined using higher order elastic constants. Other ultrasonic parameters such as Gruneisen numbers, acoustic coupling constants and acoustical anisotropy have been also calculated to discuss the ultrasonic properties of the ternary alloys. The ultrasonic wave propagation behavior at different temperatures for Ni-Al-Cr alloy have been investigated and correlated with respect to the microstructural phenomena during the wave propagation and thermal behavior of the ternary alloy. An ultrasonic mechanism has been developed to correlate the temperature dependent ultrasonic properties with the thermophysical properties particularly the thermal conductivity of the alloy. The results are compared with earlier studies of the elastic constants and are found to be in good agreement. We find that the thermal conductivity of Ni-Al-Cr alloy plays important role in the ultrasonic wave propagation behavior inside the alloy.

Keywords

Ternary Alloy, Elastic Constants, Ultrasonic Attenuation, Thermal Properties.

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A. Joseph ¹, Govind K. Sharma ¹, T. Jayakumar ¹

Affiliations
1 Non-Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, Tamil Nadu, IN

Abstract

Ultrasonic Internal Rotary Inspection System (IRIS) is used for inspection of tubes of heat exchangers and steam generators. The system displays circumferential cross section of tubes (wall thickness of tubes) at any given axial position and reveals both uniform and localised (pitting) corrosion. In this paper, the operating principle of IRIS and comparison of wall thickness measurements by physical and IRIS methods are briefly explained. Details of studies carried out on the resolution capabilities of IRIS in stainless steel and brass tubes having artificial defects (holes) are discussed. The results obtained from a study carried out on a carbon steel tube with artificial defects under baffle plate are also discussed in this paper.

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K. Sakthipandi ¹, V. Rajendran ¹, T. Jayakumar ²

Affiliations
1 Centre for Nano Science and Technology, K S Rangasamy College of Technology, Tiruchengode-637215, Tamil Nadu, IN
2 Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, Tamil Nadu, IN

Abstract

Ultrasonic non-destructive evaluation (NDE) technique is a versatile and sensitive tool for structural/microstructural and defect characterisation of materials. An indigenous experimental set-up developed in the authors’ laboratory is used for online ultrasonic velocities and attenuation measurement over a wide range of temperatures from room temperature to 1100 K. The measured ultrasonic parameters such as ultrasonic velocities and derived elastic constants are used to assess changes in microstructural features as a function of temperatures. The first order differentials of the temperature dependent ultrasonic parameters are used to reveal the precise information about the structural/phase transitions. In the present investigation, ultrasonic longitudinal velocity measurements carried out in β-quenched Zircaloy-2 specimens in the temperature range of 298 to 623 K clearly reveal formation of intermetallic precipitates from the β-quenched martensite phase. It is observed that the first order differential plots of variation in ultrasonic velocity as function of temperature is an effective tool in predicting the temperatures at which the structural changes take place. In addition, the fatigue and the creep-fatigue damages in AISI 316 stainless steel are correlated with on-line ultrasonic velocity measurements, particularly made at elevated temperatures. The results reveal that in-situ high temperature ultrasonic measurements enable assessment of creep and fatigue damage with high sensitivity.

Keywords

Ultrasonic Velocity, β-Quenched Zircaloy-2, AISI 316 L (N) Stainless Steel.

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B. K. Vasanth ¹, P. Palanichamy ², T. Jayakumar ², B. N. Sankar ¹

Affiliations
1 Physics Department Anna University, Chennai-600025, IN
2 Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, IN

Abstract

The knowledge of residual stresses in engineering structures is important for ensuring their reliable performance, structural integrity and life assessment and extension. Welded components are of major concern as it is well known that welding processes generate considerable residual stresses that are detrimental to the performance of the components. Several destructive, semi destructive and non destructive techniques are in use for the quantitative assessment of residual stresses in welded joints. Ultrasonic non destructive techniques are useful for the assessment of surface, subsurface and bulk residual stresses. In the present work, application of critically refracted longitudinal (LCR) waves for the estimation of surface/sub-surface residual stresses in a 20 mm thick single " V" butt joint fabricated from carbon steel plates is explored. Transit time measurements were made at different locations across the weld, for the L_CR waves propagating along the weld direction (longitudinal direction) representing the longitudinal stresses in the weld joints, using 2MHz L_CR wave probe assembly. Repeatability in the transit time measurements is found to be within 2 ns. For accurate measurement of the transit time, cross-correlation technique was implemented in Lab VIEW. The measurements carried out across the carbon steel weld joint clearly establish the capability of the L_CR wave based technique and the reliability of the inhouse designed and developed transducer assembly for residual stress measurements, after establishing the acoustoelastic constant for L_CR waves.

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T. Jayakumar ¹

Affiliations
1 Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kaipakkam 603 102, IN

Abstract

I consider it as a great honor for me and my colleagues at Metallurgy and Materials Group In Indira Gandhi Centre for Atomic Research (IGCAR) that I have been selected for this year's Sir L. P. Mishra Memorial Lecture by the Indian Institute of Welding (IIW-INDIA). Sir L. R Mishra Is a highly respected welding engineer who worked for Indian Railways and Hindustan Motors. He was the chairman of the first professional body (Indian Branch of Institute of Welding, London) of welding engineers In the country and he took Initiative to transform this body Into the Indian Institute of Welding, as we know today. It Is a great privilege that I have been invited to deliver a lecture Instituted In his honour. I also find the earlier recipients of this honour Include eminent experts Including Mr. M. N. Dastur, Mr S. V. Nadkarni and Mr. R S. Viswanath, to name a few. I thank IIW-INDIA with all humility for considering me one among these Illustrious welding professionals.

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