| 摘要 |
PURPOSE:To facilitate easy and assured discrimination for the defects existing within an object to be inspected even if they are cracks produced around a welded part, by irradiating an ultrasonic wave to the object to be inspected and then discriminating the phase of the echo of the ultrasonic wave. CONSTITUTION:A pulse type ultrasonic wave is radiated into an object 3 to be inspected from an ultrasonic wave transmitter/receiver 2 with a prescribed incident angle while the outer surface of the object 3 is scanned by a probe 1 in the direction of an arrow mark. It is rare that the echo of the ultrasonic wave given from the inner surface of the object 3 is reflected toward the probe 1 owing to the positional relation between the incident angle and a reflector. Thus the receiving level is small. However, the receiving level is large for the ultrasonic echo if it is given from a crack F or a welding drop W. In this case, the ultrasonic wave echo is reflected twice with the crack F, and the ultrasonic wave echo is reflected once with the drop W respectively. This difference of reflections is detected in the form a of difference of phases. |
