| 摘要 |
PROBLEM TO BE SOLVED: To provide a C-scan ultrasonic flaw detection method and apparatus that can test a full section in a plate thickness direction with a single scan by eliminating a dead zone near the surface of a tested plate and can detect even the form of a micro internal flaw. SOLUTION: An ultrasonic transmitter emits point-focused ultrasonic waves onto a tested plate substantially perpendicularly. An ultrasonic receiver receives both reflected waves of the ultrasonic waves reflected by the top of an internal flaw toward the obverse surface of the tested plate, reflected by the obverse surface and propagated into a liquid from the reverse surface until received, and reflected waves of the ultrasonic waves reflected first by the reverse surface of the tested plate toward the internal flaw, reflected by the bottom of the internal defect and propagated into the liquid from the reverse surface until received. From amplified received signals, the signal by the reflected waves from the internal flaw having the longer propagation distance is extracted. According to the extracted signal, the internal flaw is detected in the tested plate. COPYRIGHT: (C)2005,JPO&NCIPI
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