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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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P. Palanichamy ¹, A. Joseph ¹, K. V. Kasiviswanathan ¹, D. K. Bhattacharya ¹, Baldev Raj ¹

Affiliations
1 Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, IN

Abstract

This paper discusses the results of measurement of residual stress pattern across butt weld joints by ultrasonic velocity measurements in 15 mm and 47 mm thick AISI type 304 stainless steel plates. These are supplemented by results obtained from hole drilling strain gauge measurements. Pulse echo overlap technique was used to measure the through thickness longitudinal ultrasonic velocities. Acoustoelastic constant was determined to convert the change in ultrasonic velocities to residual stress values. The residual stress pattren obtained by the two techniques showed similar trends. Brief overview of various other residual stress measurement methods, and various techniques for ultrasonic velocity measurements are included in the paper.

Keywords

Residual Stress, Austenitic Stainless Steel, Weld Joint, Ultrasonic Velocity, Acoustoelastic Constant, Strain Guage Technique.

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P. Palanichamy ¹, M. Vasudevan ¹, A. Joseph ¹

Affiliations
1 Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102, IN

Abstract

Ultrasonics based nondestructive testing techniques have been effective not only for flaw detection and evaluation purposes in materials but also for the characterization of materials properties and microstructures. In this paper, some of the important non-destructive research&developmental works carried out at the authors' laboratory on the characterization of material properties (microstructures and mechanical properties) in a variety of structural materials such as AISI type 316 austenitic stainless steels (SS), modified alloy D9 and Zircaloy-2 are discussed. Potential use of high frequency (>20MHz) ultrasonic measurements for characterisation of precipitation in AISI type 316LN SS that has a bearing on the properties and performance of the materials in service will be highlighted. Application of very high frequency (?1GHz) through scanning acoustic microscopy for various surface and sub-surface imaging of sensitized microstructures will be discussed.

Keywords

Silver Halides, Elastic Properties, Ultrasonic Properties.

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S. Rajakarthihan ¹, K. Gangadevi ¹, A. Anitha ¹, P. Palanichamy ²

Affiliations
1 Department of Physics, Thiagarajar College, Madurai-625009, IN
2 Non-Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, IN

Abstract

Polymethylmethacrylate (PMMA) sample of 10 mm thickness and 15 mm diameter were prepared form a half a meter rod and exposed to ϒ-ray dose of different duration in an irradiation chamber with Ir-192 source. The polymer has been subjected to gamma radiation from 45 to 177 mGy dosages. Characterization by Ultrasonics, Fourier transform infra-red spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) was done before and after irradiation. Precise ultrasonic measurements were made in the irradiated sample using 2 MHz longitudinal ultrasonic wave contact type transducer. Ultrasonic velocity measurements have been employed to investigate the microstructural changes in the irradiated sample. It was found that there is a decrease in velocity as the exposed dose is increased. FTIR study for the irradiated samples shows the enhanced CH stretching vibration. The UV-Vis studies for the irradiated samples indicate the shift in wavelength of absorption bands with the increasing irradiation dose was recorded. The result shows the variation in structural and optical properties of PMMA which is helpful for its stability under mild dose irradiations.

Keywords

ϒ-Ray Irradiation, Ultrasonic Velocity, FTIR, UV-Visible.

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P. Palanichamy ¹, M. Vasudevan ¹

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

Abstract

In recent years, ultrasonic measurements are found to offer unique and nondestructive methods of determining the microstructures and quantifying residual stresses. Ultrasonic techniques developed based on velocity measurements are found to be more reliable than the existing techniques for characterizing the annealing behaviuor of cold worked austenitic stainless steel. The variation in ultrasonic velocity with annealing time/temperature exhibited three stages. Based on the microstructural investigations using metallography, the three stages have been identified to be recovery, progress of recrystallization and completion of recrystallization. Ultrasonic based residual stress measurements are nondestructive and offer quantitative estimation of surface/sub-surface and bulk residual stresses. In the present work, critically refracted longitudinal L_CR waves have been employed to measure residual stresses in A-TIG weld joints of type 316 LN stainless steel of various thickness. There was significant reduction in the magnitude of tensile residual stresses in A-TIG weld joints with increasing thickness of the plates joined. This residual stress measurement technique has several advantages including high spatial resolution for longitudinal residual stresses across the weld joints, easy and simple to use on fabricated components, cost effective and non-destructive.

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S. Raja Karthihan ¹, T. M. Haridasan ², P. Palanichamy ³, C. K. Mukopadhyay ³, P. Kalyanasundaram ³,

Affiliations
1 Department of Physics, Sethu Institute of Technology, Kariapatti-626106, IN
2 School of Energy, Madurai Kamaraj University, Madurai-625021, IN
3 Division for PIE & NDT Development, Indira Gandhi Center for Atomic Research, Kalpakkam-603102, IN

Abstract

A biomass gasifier was in operation for sometime and later failed near the weld portion. A portion of the sample near the failed region was cut and used for this investigation. Study based on ultrasonic velocity measurements, metallography and X-ray diffraction was carried out at different portions of samples of stainless steel used in the biomass gasifier. Precise ultrasonic velocity measurements were performed by pulse echo method using cross correlation technique. Longitudinal ultrasonic wave generating probes of 5 and 20 MHz were used. It is found that there is an increase in ultrasonic velocity in samples obtained from the exposed portion as compared to the virgin samples. Metallographic studies revealed that there is a microstructural reformation taking place due to prolonged temperature treatment at the regions away from the failed portion. Very near the failed portion, there is intergranular type crack propagation as a result of partial sensitization and embrittlement. X-ray diffraction study is in support of the metallographic observations. The increase in ultrasonic velocities in service exposed specimen with and without intergranular cracks was attributed to the continuous changes taking place in the microstructures. It is suggested that periodic monitoring of the critical parts especially the combustion zone by NDE techniques would help avoid premature failure of the biomass gasifier plant.

Keywords

Ultrasonic Measurements, Biomass Gasifier, AISI Type 310 Stainless Steel, Microstructures, Characterization.

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P. Palanichamy ¹

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

Abstract

Over last two decades, significant progress has been made on the characterisation of microstructures and material properties using ultrasonic attenuation and velocity measurement methods. Ultrasonic characterisation of microstructural feature in nuclear structural materials is a challenging and a very useful task to the industries. In this paper, some of the important developmental works carried out on characterisation of microstructures in a variety of nuclear structural materials such as AISI type 316 austenitic stainless steels, modified alloy D9, and Zircaloy-2 are presented. Potential of high frequency (>20 MHz) ultrasonic measurements for characterisation of precipitation that have a bearing in the properties and performance of the materials in service has also been highlighted. Paper also discusses the use of very high frequencies in the GHz range through scanning acoustic microscopy for the characterisation of sensitized microstructures in AISI type 304 LN stainless steel.

Keywords

Ultrasonics, Attenuation, Velocity, Microstructural Characterisation, Nuclear Structural Materials, High Frequency, Scanning Acoustic Microscopy, Sensitisation.

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S. Raja Karthihan ¹, T. M. Haridasan ², C. Sanjeevi Raja ³, P. Palanichamy ⁴, C. K. Mukhopadhyay ⁴, P. Kalyanasundaram ⁴

Affiliations
1 Department of Physics, Thiagarajar College, Madurai-625009, IN
2 School of Energy, Madurai Kamaraj University, Madurai-625021, IN
3 Department of Physics, Alagappa University, Karaikudi-623001, IN
4 Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, IN

Abstract

AISI type 310 stainless steel is currently in demand for the biomass gasifier plants in India as the main structural material. During operation of the plant this steel undergoes temperature as high as 1373 K and variation in temperature and stress. In this work, we have received virgin and service exposed sample cut near the weld failure region of AISI type 304 SS suitably prepared and used for ultrasonic velocity measurements, acoustic emission testing (AET) and photoacoustic (PA) measurements on the virgin and service exposed specimens of AISI type 310 high temperatures steel with the aim to use the outcome of the study to increase the life cycle of the steel and hence the biomass plant. Acoustic emission (AE) test results indicate that as compared to the virgin specimens, strength increases and ductility decreases for the service-exposed specimens. AE generated is also higher for the service-exposed specimens as compared to the virgin specimens. Ultrasonic velocity measurements show comparatively higher velocity in service exposed specimen than in virgin specimen and the hardness measurements show opposite trend to that of ultrasonic measurements. The studies clearly indicate the immense possibility of the applying NDT techniques in assessing the service degradation taking place during the gasifier. In addition, Metallography and Photoacoustics (PA) measurements were also conducted on the specimens. It is found that PA measurements results found to correlate well with the above measurement results.

Keywords

Biomass Gasifier, High Temperature Steel, Ultrasonic Nondestructive Testing.

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P. Palanichamy ¹

Affiliations
1 Nondestructive Testing Division, IGCAR, Kalpakkam, IN

Abstract

Dr. Baldev Raj, a Distinguished Scientist, Padma Shree Awardee, renowned administrator of nuclear power science and technologies of our country and the Director of the National Institute of Advanced Studies (NIAS), Bengaluru, passed away on January 6, 2018, aged 70 at Pune. Raj had assumed leadership of the NIAS in 2014. Previously, he had served as the President of Research at P.S.G. Institutions (2011-2014), Coimbatore, and as the Director of the Indira Gandhi Centre for Atomic Research (2004-2011), Kalpakkam. Born on April 9, 1947, he had a distinguished degree in metallurgy from NIT Raipur, completed his Ph.D. in Engineering from the Indian Institute of Science during 1989. Dr. Raj had his initial training in nuclear technology from the Bhabha Atomic Research Centre (BARC), Trombay.

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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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A. Mohamed Ali ¹, N. Arunainambi Raj ², S. Kalainathan ², P. Palanichamy ³

Affiliations
1 Department of Physics, C. Abdul Hakeem College, Melvisharam-632509, IN
2 Department of Physics, V I T University, Vellore-632014, IN
3 NDED, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, IN

Abstract

Standardized and reproducible artificial kidney stone models are necessary and important for performing comparative studies in order to improve stone treatment modalities. Artificial kidney stone models made out of natural substances viz. tri-Calcium phosphate (Whitlockite) and Calcium hydrogen ortho phosphate dihydrate (Brushite) were prepared by pharmaceutical methods involving granulation, tableting and coating. These stones are found be very much similar to real kidney stones. Ultrasonic velocity measurements were made using longitudinal and transverse probes and the corresponding wave impedances and dynamic elastic moduli of these two groups of artificial stone models were studied and reported. The compositions of the stones were verified using FTIR and X-ray diffraction analysis. The results indicate that the properties of artificial stones made of natural stone materials are comparable to renal calculi of the same chemical composition. These data also suggest that these stone phantoms are suitable for performing standardized and reproducible in vitro investigations, especially with regards to fragility of kidney stones during shock wave lithotripsy.

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