| 摘要 |
PROBLEM TO BE SOLVED: To detect cracks in a narrow place, such as a weld at the end of the member of an iron beam. SOLUTION: The eddy-current flaw detection probe 10 of a differential coil method is provided with a magnetic core 14, which is extended nearly in parallel with an inspected surface S, a first coil 15 which is wound up to substantially the center from one end of the magnetic core 14 and a second coil 16, which is wound up to the other end substantially from the center of the magnetic core 14. When the probe 10 determines whether a defect is caused on the surface S, it scans the face S nearly in parallel, while it is keeping a posture in which the magnetic core 14 is substantially parallel to the face S. When a defect does not exist in a scanning range, a coil impedance is not changed. When defects such as the crack or the like exist in the scanning range, the coil impedance is changed. Consequently, by investigating whether the coil impedance is changed, whether the defect, such as the crack or the like, is caused in the scanning range can be determined.
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