Ultrasonic flaw detection method and apparatus for welds

摘要

Provided is an ultrasonic flaw detection method and apparatus capable of accurately detecting flaws present in a welded portion of a flaw detection material such as a welded pipe regardless of the position where the flaw is present. The ultrasonic flaw detector 100 includes n (n ≧ 2) vibrators 11 arranged along a direction orthogonal to the weld line of the weld part P1 of the flaw detection material P, and is disposed to face the weld part. Select m transducers (n m ≧ 1) from the ultrasonic probe 1 and n transducers, and transmit and receive ultrasonic waves from the selected transducers to the weld and select them Transmission / reception control means 2 for sequentially switching the vibrators. The transmission / reception control unit sequentially switches the selected transducers so that the range of effective beam widths for the detection target flaws of each switched selected transducer overlaps. The flaw detection sensitivity is adjusted in advance for each selected transducer so that the maximum echo intensities from the detection target flaws received are substantially equal.