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Academic Articles

Regular Paper

Vol.13 No.2 (2022) p.14 - p.25

Evaluation of the Capability to Estimate a Crack Profile by 3D SAFT-UT

Yoshinori KAMIYAMA¹, Toshihiro YAMAMOTO¹ and Takashi FURUKAWA¹

¹Japan Power Engineering and Inspection Corporation, 14-1 Benten-cho, Tsurumi-ku, Yokohama 230-0044, Japan

Abstract

In nuclear power plants, inservice inspection (ISI) is periodically performed to maintain the pressure boundary integrity of components and piping. During ISI, a nondestructive testing method must find flaws and provide information required to determine flaw sizes when flaws are found. The aim of this study is to show synthetic aperture focusing technique for UT utilizing FMC/TFM and a matrix array transducer can more robustly provide accurate crack sizing results than commonly used UT methods. This advanced UT method (referred to as 3D SAFT-UT) and phased array UT using a linear array transducer were performed on nickel-base alloy test blocks with a thermal fatigue crack to compare their results. Phased array UT can obtain tip echoes only at rather flat part of a crack profile, whereas 3D SAFT-UT can obtain tip echoes over a wide range of a crack and estimate its crack profile. To evaluate the sizing stability against the variation in the azimuth angle of the incident direction, the capabilities to estimate a crack depth with different azimuth angles were compared between phased array UT and 3D SAFT-UT. The results show 3D SAFT-UT can provide relatively good crack profile and crack depth estimations even if the transducer is not right in front of the crack.

Keywords

Synthetic aperture focusing technique, SAFT, FMC/TFM, ultrasonic testing, UT, matrix array transducer, crack profile, thermal fatigue crack

Full Paper: PDF

Article Information
Article history:
Received 27 September 2021
Accepted 26 January 2022


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