Examination of Flaw Detection near the Surface by the Ultrasonic TOFD Method

The ultrasonic Time-of-Flight-Diffraction (TOFD) method detects diffraction from flaw tips, and it is possible to recognize the flaw size and the position with high accuracy by measuring time of flight. It is difficult to detect flaws near the surface (less than 10 mm from the surface), because flaw...

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Bibliographic Details
Published in:Key engineering materials 2004-01, Vol.270-273, p.378-383
Main Authors: Furuta, Hiroyuki, Ido, Nobukazu, Katou, Kenji, Hatanaka, Hiroaki, Arakawa, Takahiro
Format: Article
Language:English
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Summary:The ultrasonic Time-of-Flight-Diffraction (TOFD) method detects diffraction from flaw tips, and it is possible to recognize the flaw size and the position with high accuracy by measuring time of flight. It is difficult to detect flaws near the surface (less than 10 mm from the surface), because flaw indications are hidden in the lateral wave. To detect flaws near the surface clearly, one-skip TOFD method and signal processing were examined. One-skip TOFD method detects diffraction waves from flaws near the surface after reflection at the back-wall. Optimum conditions for detecting flaws were calculated and they were examined empirically. Furthermore, to improve the signal-to-noise (SN) ratio, the wavelet transform method was applied and efficiency of signal processing was confirmed. (Example material: steel.)
ISSN:1013-9826
1662-9795
1662-9795
DOI:10.4028/www.scientific.net/KEM.270-273.378