Electromagnetic modeling of fatigue cracks in plant environment for eddy current testing

Issue title: Selected Papers from the 15th International Symposium on Applied Electromagnetics and Mechanics (ISEM 2011)

Article type: Research Article

Authors: Uchimoto, Tetsuya^{a; *} | Takagi, Toshiyuki^a | Ohtaki, Keitaro^b | Takeda, Yoichi^b | Kawakami, Akira^c

Affiliations: [a] Institute of Fluid Science, Tohoku University, Sendai, Japan | [b] School of Engineering, Tohoku University, Sendai, Japan | [c] Thermal & Nuclear Power Division, Tohoku Electric Power Co., Inc. Sendai, Japan

Correspondence: [*] Corresponding author: Tetsuya Uchimoto, Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan. Tel./Fax: +81 22 217 5262; E-mail: uchimoto@ifs.tohoku.ac.jp

Abstract: This study discusses the electromagnetic modeling of fatigue cracks in plant environment to improve accuracy of depth sizing with eddy current testing. For the purpose, the factors that influence eddy current signals of fatigue cracks are evaluated. Here, martensitic layer and oxide fillings in fatigue cracks are focused on as influencing factors, and oxides are systematically filled in fatigue cracks by thermal treatment. The measured EC signals change depending on the presence and type of filling oxides. Numerical simulations are conducted to discuss the electromagnetic modeling of cracks with oxide fillings. The types of oxides in the cracks are identified by Raman spectroscopy, and the martensitic layers in vicinity of crack faces are observed by magnetic force microscopy. These results support for the electromagnetic model of environmental fatigue cracks developed in this study.

Keywords: Eddy current testing, environmental fatigue, depth sizing, oxidation, martensitic phase

DOI: 10.3233/JAE-2012-1469

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 39, no. 1-4, pp. 261-268, 2012