| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for detecting the nitriding layer formed on the outer surface of a radiation pipe easily and certainly. SOLUTION: In the method for detecting the nitriding layer formed on the outer surface of the radiation pipe by an electromagnetic induction method, a measuring probe, which is equipped with a ring-shaped permanent magnet, the first coil provided on the outside of this permanent magnet and the second coil provided on the inside of the permanent magnet, is provided so as to be adjacent to the surface of the radiation pipe to perform measurement. When (1) the relation of the phase angle of the impedance of the first coil and the amplitude thereof is calculated or (2) the relation of the amplitude of the impedance of the second coil and that of the first coil is calculated, the radiation pipe is judged to have the nitriding layer in a case showing an amplitude value above that of the radiation pipe only of a healthy layer but below that of the radiation pipe not having the nitriding layer but having a carburizing layer. COPYRIGHT: (C)2005,JPO&NCIPI
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