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Vol.5 No.3 previous AA 72-73-NT 60 -61 - 62

Academic Articles
Regular Paper Vol.5No.4 (2014) p.201 - p.227
 

Visualization and Quantitative Evaluation of Stress Corrosion Cracking Using the Three-Dimensional Phased Array Ultrasonic Technique

 
So KITAZAWA1, Naoyuki KONO1*, Atsushi BABA2, Katsumi ISAKA3, Hidetaka KOMURO3, Mitsuru ODAKURA3, Kazuya EHARA3, Yasuhiro NIDAIRA3, Yutaka KOMETANIM3, Takeshi KUDO4 and Osamu KIKUCHI5
 
1Hitachi, Ltd., Research & Development Group, Hitachi Research Laboratory, 7-2-1 Omika-cho, Hitachi-shi, Ibaraki-ken 319-1221, Japan
2Hitachi, Ltd., Research & Development Group, Technology Strategy Office, 1-6-1 Marunouchi, Chiyoda-ku, Tokyo 100-8220, Japan
3Hitachi-GE Nuclear Energy, Ltd., Hitachi Works, 3-1-1 Saiwai-cho, Hitachi-shi, Ibaraki- ken 317-0073, Japan
4Hitachi, Ltd., Power Systems Company, Hitachi Works, 3-1-1 Saiwai-cho, Hitachi-shi, Ibaraki- ken 317-8511, Japan
5Hitachi Power Solutions Co., Ltd., 730 Horiguchi, Hitachinaka-shi, Ibaraki- ken 312-8504, Japan
 
Abstract
The three-dimensional phased-array (3D-PA) ultrasonic technique has been applied to stress corrosion cracking (SCC) in base metal, and its results for sizing have been quantitatively evaluated. The 3D-PA allows operators to scan objects volumetrically and to display results as 3D images facilitating evaluation processes considerably. First, a slit produced by electrical discharge machining was examined to verify basic properties of the 3D-PA. The scanning pattern used is called the moving rotational S-scan (MRS-scan) that is composed of many sectors of different azimuth angles as moving the probe linearly. The MRS-scan significantly improves the inspection of flaws without skillful searching motion of the probe, because the flaws are stereoscopically insonified by a number of ultrasonic beams coming from various directions. Next, SCC cracks were evaluated by the MRS-scan with a matrix array probe that transmitted longitudinal waves of a center frequency of 2 MHz. Not only the deepest part of the cracks but also all parts of them were able to be successfully visualized and sized with an accuracy of the root mean square error of 0.9 mm. In the case of rough inspections just to find flaws with freehand motion of the probe, online real-time 3D-PA demonstrated its capability for fast and easy comprehension of flaw signals. In combination with offline and real-time techniques, ultrasonic testing was made more efficient and more reliable than in conventional techniques.
 
Keywords
ultrasonic testing, phased array, three-dimensional, stress corrosion cracking, matrix array probe, real-time scan
 
Full Paper: PDF EJAM Vol.5No.4 pp.201-227 "Visualization and Quantitative Evaluation of Stress Corrosion Cracking Using the Three-Dimensional Phased Array Ultrasonic Technique"
















Article Information
Article history:
Received 27 September 2013
Accepted 16 January 2014