Ultrasonic measurements for in-service assessment of wrought Inconel 625 cracker tubes of heavy water plants

Kumar, Anish; Rajkumar, K.V.; Jayakumar, T.; Raj, Baldev; Mishra, Biswajit

doi:10.1016/j.jnucmat.2006.01.011

Cited by 23 publications

(10 citation statements)

References 9 publications

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“…Similar results of larger influence on ultrasonic shear wave velocity as compared to longitudinal wave velocity have been reported earlier also for precipitation of intermetallics in other alloys. [25,26] The higher influence of reversion of austenite on the longitudinal wave velocity can be explained by comparing the ultrasonic velocities in martensitic and austenitic steels. The difference in the ultrasonic longitudinal wave velocity for the two steels is greater as compared to that of the shear wave velocity.…”

Section: A Microstructural Investigationsmentioning

confidence: 99%

Characterization of Aging Behavior in M250 Grade Maraging Steel Using Ultrasonic Measurements

Rajkumar

Kumar

Jayakumar

et al. 2007

Metall Mater Trans A

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Ultrasonic measurements have been carried out in M250 grade maraging steel specimens subjected to solution annealing at 1093 K for 1 hour followed by aging at 755 K for various durations in the range of 0.25 to 100 hours. The influence of aging on microstructure, room temperature hardness, and ultrasonic parameters (longitudinal and shear wave velocities and Poisson's ratio) has been studied in order to derive correlations among these parameters in aged M250 maraging steel. Both hardness and ultrasonic velocities exhibit almost similar behaviors with aging time. They increase with the precipitation of intermetallic phases, Ni 3 Ti and Fe 2 Mo, and decrease with the reversion of martensite to austenite. Ultrasonic shear wave velocity is found to be more influenced by the precipitation of intermetallic phases, whereas longitudinal wave velocity is influenced more by the reversion of martensite to austenite. Unlike hardness and ultrasonic velocities, the Poisson's ratio exhibits a monotonous decrease with aging time and, hence, can be used for unambiguous monitoring of the aging process in M250 maraging steel. Further, none of the parameters, i.e., hardness, ultrasonic velocity, or Poisson's ratio, alone could identify the initiation of the reversion of austenite at early stage; however, the same could be identified from the correlation between ultrasonic velocity and Poisson's ratio, indicating the advantage of using the multiparametric approach for comprehensive characterization of complex aging behavior in M250 grade maraging steel.

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Section: A Microstructural Investigationsmentioning

confidence: 99%

Characterization of Aging Behavior in M250 Grade Maraging Steel Using Ultrasonic Measurements

Rajkumar

Kumar

Jayakumar

et al. 2007

Metall Mater Trans A

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“…In the nuclear field, it may be used for reactor-core and control-rod components in pressurized water reactors and as heat exchanger tubes in ammonia cracker plants for heavy water production. The components in these applications are subjected to a complex combination of elevated temperatures, high stress, and hostile environmental conditions [1][2][3]. For this superalloy, controlling the hot working process to obtain a homogeneous microstructure seems to be very important [4].…”

Section: Introductionmentioning

confidence: 99%

Investigation on hot workability characteristics of Inconel 625 superalloy using processing maps

Guo

et al. 2012

J Mater Sci

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Hot compression tests of the commercial Inconel 625 were performed in the temperature range of 950-1200°C and strain rate range of 0.01-10 s -1 . The flow behavior and processing maps were investigated using the corrected flow stress data to eliminate effects of the friction and adiabatic heating. The processing maps have exhibited a domain in the temperature range of 1100-1200°C and strain rate range of 0.01-10 s -1 corresponding to the higher efficiency of power dissipation. Microstructural observations reveal that the full dynamic recrystallization (DRX) occurs in this domain, which is optimum processing window for hot working to obtain a homogeneous microstructure. DRX grain growth occurs in the temperature range of 1150-1200°C and strain rate range of 0.01-0.1 s -1 . In view of the refined and uniform grains obtained by hot deformation, the finish forming processing should be selected the deformation conditions in which the full DRX occurs without the grain growth. The small regimes of flow instability are noticed at temperature below about 970°C at the different strains. The material undergoes flow instability manifesting as bands of flow localizations and high density deformation twins. In addition, it is found that the undissolved second-phase particles and carbides can promote the DRX processing and be helpful to restrict the DRX grain growth.

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“…After 120,000 h of service exposure, these tubes are generally taken out of the cracker unit to give a resolution annealing treatment at a suitable temperature to restore the toughness by dissolution of intermetallic precipitates. A nondestructive methodology, based on in-situ ultrasonic and hardness measurements, has been developed and implemented at two Indian heavy water plants for the assessment of in-service degradation and rejuvenation heat treatment of wrought ammonia cracker tubes [11].…”

Section: Ultrasonic Technique For Assessment Of Inservice Degradationmentioning

confidence: 99%

“…Times of flight of ultrasonic longitudinal and shear waves have been measured in-situ on cracker tubes in different conditions, such as virgin, virgin tubes service-exposed for different durations, resolution annealed tubes and resolution annealed tubes service-exposed for different durations [11]. The results obtained from Poisson's ratio (derived from measurement of times of flight of ultrasonic longitudinal and shear waves) and hardness measurements on all the tubes are presented in Fig.…”

Section: Ultrasonic Technique For Assessment Of Inservice Degradationmentioning

confidence: 99%

Non-destructive evaluation techniques for assessment of creep and fatigue damage in materials and components

Jayakumar

Mukhopadhyay

2010

Trans Indian Inst Met

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In this article, application of various non-destructive evaluation (NDE) techniques for assessment of creep and fatigue damage in materials and components has been discussed. X-ray diffraction technique has been used for finding fabrication-induced residual stresses in components. Ultrasonic and magnetic techniques have been applied for characterizing changes in microstructures due to creep and fatigue. Crack closure phenomenon and fatigue crack growth have been studied in austenitic stainless steels using acoustic emission technique. Dual-frequency eddy current technique has been used for high sensitive detection of fatigue cracks in compressor discs of aeroengines.

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Ultrasonic measurements for in-service assessment of wrought Inconel 625 cracker tubes of heavy water plants

Cited by 23 publications

References 9 publications

Characterization of Aging Behavior in M250 Grade Maraging Steel Using Ultrasonic Measurements

Characterization of Aging Behavior in M250 Grade Maraging Steel Using Ultrasonic Measurements

Investigation on hot workability characteristics of Inconel 625 superalloy using processing maps

Non-destructive evaluation techniques for assessment of creep and fatigue damage in materials and components

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