Informatics Publishing Limited

A. Joseph ¹, T. N. Rajan ²

Affiliations
1 Indian National Scientific Documentation Centre, Hillside Road, New Delhi-110 012, IN
2 Indian National Scientific Documentation Centre, Hillside Road, New Delhi -110 012, IN

Abstract

Focusses Insdoc's experience In handling patent demands, procurement and supply service. An analysis of data on the service for the last five years (1972-75) is presented. A brief survey of world patent sources and services is made. Indicates the possible future trends in the patent system and consequently the patent information system.

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A. Joseph ¹, Govind K. Sharma ¹, B. Purnachandra Rao ¹, K. Nataraj ²

Affiliations
1 Nondestructive Evaluation Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, IN
2 Department of Physics, National Institute of Technology, Trichy-620015, IN

Abstract

Low carbon steel is the most commonly used material for various applications because its cost is relatively low. Different methods are employed to reduce residual stresses in carbon steel weld joints. Post weld heat treatment (PWHT) is the most commonly used method to relieve/reduce the residual stresses. Use of different sequential weld passes during welding is one of the alternate methods used to get minimum residual stresses in higher thickness double 'V' carbon steel weld joints. A study was undertaken to nondestructively quantify the residual stresses present in carbon steel weld joints made using three different weld pass sequences. For this study, three sets of 20.0 mm thick low carbon steel double 'V' weld joints were fabricated with three different weld pass sequences using the Manual Metal Arc Welding (MMAW) process. Ultrasonic based residual stress measurements offer estimation of surface, sub-surface and bulk residual stresses. Details of critically refracted longitudinal (L_cr ) ultrasonic wave technique employed for residual stress measurements are discussed in this paper. The residual stress values of carbon steel weld joints obtained using the ultrasonic L_cr technique showed minimum longitudinal tensile residual stresses in the weld joints made by alternate weld pass sequence as compared to the other two weld pass sequences. The ultrasonic L_cr technique used is nondestructive, portable and low cost technique for residual stress measurements. This technique can also be used for in-situ measurement of residual stresses in operating components.

Keywords

Residual Stress, Ultrasonic Technique, Carbon Steel, Sequential Welding Passes.

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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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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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