| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus, for an ultrasonic flaw detection, in which a blowhole-shaped very small defect generated in a weld can be detected with good accuracy and in an on-line manner and in which the generation position of the defect can be grasped easily. SOLUTION: One array probe 3 and a wedge 4 which holds the array probe 3 in such a way that an ultrasonic beam radiated vertically from the array probe becomes a prescribed angle of refraction are used. The depth direction of a weld 2 is sector-scanned. At this time, the angle step of a sector scanning operation is set in such a way that respective scanning beams are overlapped. The focusing point of respective scanning lines is aligned with the weld 2, and a flaw is detected. |
