ULTRASONIC PROBE, ULTRASONIC FLAW DETECTOR, ULTRASONIC FLAW DETECTING METHOD AND PRODUCTION METHOD OF SEAMLESS PIPE

摘要

A ultrasonic flaw detecting method comprising the step of disposing a ultrasonic probe (1) provided with a plurality of vibrators (11) to face a tubular object to be detected P, and the step of selecting a proper vibrator from the plurality of vibrators to have it transmit/receive a ultrasonic wav e so that the propagation direction of a ultrasonic wave within the tubular object to be detected has a plurality of different propagation directions, characterized in that a flaw detection condition by the ultrasonic probe is set so that the external refraction angles .theta.r of the ultrasonic wave f or the plurality of propagation directions are respectively almost equal and/or the internal refraction angles .theta.k of the ultrasonic wave for the plurality of propagation directions are respectively almost equal.