PITCH-CATCH TYPE ULTRASONIC FLAW EXAMINATION

摘要

PURPOSE: To discriminate a direct propagation wave and a defect reflected wave distinctly from each other on the occasion of examination of a defect being parallel to the direction of propagation of an ultrasonic beam. ;CONSTITUTION: A transmission-side longitudinal wave angle probe 4a of a refractive angle 10 to 40° is disposed on one of opposite blade groove end faces 2 of a blade groove tooth part 1 which has a defect 10 being parallel to the length direction, and a similar reception-side longitudinal wave angle probe 4b is disposed on the other, respectively. The defect is detected from a time difference between a propagation time of a wall surface reflected wave 8 once reflected on a blade groove wall surface 3 and then propagated as a longitudinal wave and a propagation time for which a wall surface defect reflected wave 9 once reflected on the blade groove wall surface 3 and then converted into a lateral wave is reflected by the defect 10, propagated to the blade groove wall surface 3, then converted in a mode into the longitudinal wave again and received.;COPYRIGHT: (C)1993,JPO&Japio