ULTRASONIC PROBE, ULTRASONIC FLAW DETECTION METHOD AND ULTRASONIC FLAW DETECTION DEVICE

摘要

Minute flaws present on the interior of a high (t/D) metal pipe having a ratio (t/D) of the wall thickness t to the outer diameter D of greater than 15 % is carried out with high accuracy and certainty by angle beam flaw detection without an accompanying decrease in detection efficiency or cost increase. This is an ultrasonic probe which, as viewed from the center of a high (t/D) metal pipe, performs flaw detection of the metal pipe by obliquely impinging ultrasonic waves from a transducer on the metal pipe and generating refracted longitudinal waves and refracted transverse waves which are propagated inside the metal pipe. The front end portion of the transducer has at least a portion with an asymmetrically curved shape having a radius of curvature which progressively increases from one end towards the other end of the front end portion. The ultrasonic probe is disposed with respect to a metal pipe such that the end having the smaller radius of curvature is positioned on the side away from the direction of propagation of refracted waves, the end having a larger radius of curvature thereof is positioned on the side in the direction of propagation of refracted waves, and angle beam flaw detection is carried out under such conditions that incident waves are generated which generate refracted longitudinal waves which do not reach the inner surface of the metal pipe and refracted transverse waves which are focused on the inner surface of the metal pipe.