| 摘要 |
PURPOSE: To accurately grasp the local sonic velocity change caused by the weld section residual stress, aggregate structure, and deterioration of a practical structural material used in a plant or the like. CONSTITUTION: Ultrasonic waves are generated in pulses by transmitting probes 1a, 1b, and at least two or more ultrasonic signals having the same propagation direction and different propagation distances are received by a receiving probe 2. The ultrasonic velocity is obtained from the cycle period of ultrasonic pulses and the propagation distance difference between the ultrasonic waves that all the ultrasonic waves interfere with each other and the interference intensity becomes the maximum from the intensity change of the interference signal of the ultrasonic waves when the cycle period of propagated surface wave pulses is changed. The change of the local sonic velocity of a solid material is obtained with high accuracy. |
