This study evaluates stress corrosion cracks appearing in austenitic sta inless steel from the viewpoint of its resistance to eddy currents. Edd y current signals due to artificially introduced stress corrosion cracks are analyzed using finite element simulators to discuss its resistance . The results showed that the width and conductivity to model a stress corrosion crack vary significantly and furthermore depend on exciting f requency adopted. In contrast, however, the resistance of a crack, which is de...
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Discussion on the Minimum Resistance of Stress Corrosion Cracking From the Viewpoint of EddyCurrent Nondestructive Evaluation

Abstract: This study evaluates the applicability of eddy current testing to the detection and sizing of fatigue cracks embedded in Inconel weld overlay. Welded plate specimens, which model head penetration welds and their weld overlay, are fabricated, and fatigue cracks are artificially introduced into the specimens. Eddy current inspections are performed using a uniform eddy current probe driven with 10 kH z, and all of the fatigue cracks are detected with clear signals. Subsequent numerical inversions ...
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Detection of embedded fatigue cracks in weld overlay and evaluation of minimum thickness of the weld by means of eddy current testing

Abstract. This study discusses a suitable numerical modeling of a thermal fatigue crack from the viewpoint of eddy current testing. Five artificial thermal fatigue cracks, introduced into type 304L austenitic stainless steel plates with a thickness of 25 mm, are prepared; and eddy current inspections are carried out to gather signals using an absolute type pancake probe and a differential type plus point probe. Finite element simulations are then carried out to evaluate a proper numerical model of the...
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Numerical modeling of thermal fatigue cracks from the viewpoint of eddy current testing

This study discusses the stress corrosion cracking (SCC) model which improves accuracy of depth sizing of SCCs with eddy current testing (ECT). For this purpose, the factors that influence ECT for SCCs are evaluated. In this study, the crack morpholog y and oxide fillings in SCCs are evaluated. As a first step, SCCs introduced at room temperature and fatigue cracks with oxide fillings are evaluated. To discuss the EC signals of SCCs, SCCs are artificially introduced and their ECT signals are obtain ed. The...
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Evaluation of the influence of crack branching structure and oxide fillings of stress corrosion cracking for depth sizing based on eddy current testing

study evaluates the probability of the errors in evaluation of length and depth of ly current testing signals measured in inspections of a steam g enerator tubes in lants. Numerous numerical simulations are performed to establish database e number of defect profiles and corresponding eddy cur rent signals; then the or is calculated as a function of the difference in signals using the databases. is study clarify that the eddy current inv ersion in the configuration is not so Abstract This study evaluates t...
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Probabilistic Evaluation of Eddy Current Inverse Analyses

This study reports the results of nondestructive testing and evaluation of artificial thermal fati gue cracks using direct current potential drop method. ?ix artificial thermal fatigue cracks, intro duced into type 304L austenitic stainless steel plates with a thickness of 25mm, are prepared; and potential drops across the cracks are measured using a direct current source of approximately 80A. The specimens are then served to destructive tests to reveal the true profiles of the cracks. Fini te element simu...
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Nondestructive Testing and Evaluation of Artificial Thermal Fatigue Cracksusing Direct Current Potential Drop Method

This study evaluates the distribution of electrical contact across the surface of thermal fatigue cracks by four- terminal direct current potential drop method. This study prepared seven artificial thermal fatigue cracks, artificially introduced into Inconel or type 316L stainless steel plates with a thickness of 25 mm. Columnar specimens embedded into a resin were fabricated from the plate s to measure the electrical resistance across the cracks directly. The results indicated th at thermal fatigue crac...
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Evaluation of the electrical contacts of thermal fatigue cracks across their surfaces 東北大院・工学研究科

The PIRT process was developed as a part of the systematic and documented means of demonstrating the validation of best estimate simulation codes in USNRC licensing of nuclear power plants. In this paper the PIRT process was applied for finding influential factors giving an impact on the accuracy of ultrasonic testing and eddy current testing and related problems required to improve the accuracy and also reports the results that the problems were ranked from the viewpoint of importance, knowledge and c...
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Accuracy of Non-destructive Examination Techniques to Detect Fatigue Crack

This study develops a low frequency magnetic flux leakage testing method for monitoring a wall thinning appearing on the inner surface of a magnetic pipe. We conducted the numerical simulations to evaluate how the presence of wall thinning perturbates electromagnetic fields induced by an encircling coil. The result of the simulations shows measuring the axial component of magnetic flux density enables to detect and evaluate wall thinning. ...
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Development of low frequency magnetic flux leakage testing method aimed at monitoring a wall thinning appearing in a magnetic pipe

In this study, a new signal-processing method was developed to improve the precision of locating flaw’s position using microwave NDT. The previous processing method is available only for the single-mode microwave, which causes the noise generation in the case that multi-mode microwaves propagate in a metal pipe. In order to reduce the noise, the reflections caused by the propagation of unintended modes were extracted and deducted from the original signal. The result showed the less noise intensity and highe...
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Precision Improvement of a Method to Predict the Flaw Location on an Inner Surface of a Metal Pipe Using Multiple-mode Microwaves