Journal of Pure and Applied Ultrasonics

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.

Full Text

   

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.

Full Text

   

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.

Full Text

   

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.

Full Text

   

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.

Full Text