ULTRASONIC FLAW DETECTION APPARATUS AND FLAW JUDGEMENT METHOD

摘要

PURPOSE: To provide an ultrasonic flaw detection apparatus and a flaw judgement method which nearly eliminate an uninspected region and which can automatically detect a flaw in a material to be inspected/without using a test material which contains an artificial flaw. CONSTITUTION: In a gate part 21, a point after a definite time from the rise of outer- surface echoes in a reflected echo signal is used as a gate starting point, a gate signal which can gate inner-surface echoes is generated, and the reflected echo signal is gated. The frequency component of an amplitude change in the output signal of a peak hold part 17 is divided into the frequency component fC of an amplitude change due to the rotation of a material 4 to be inspected and into the frequency component fF of an amplitude change generated at a time when ultrasonic waves propagated inside the material 4 to be inspected are masked by a flaw. A gain-variable amplification part 24 almost removes an amplitude change portion due to the rotation of the material 4 to be inspected of the output signal of the peak hold part 17 so as to be output. A high-pass filter 25 sufficiently attenuates and removes the frequency component fC in an input signal, and it outputs only the frequency component almost which is generated at a time when the flaw is masked and whose amplitude change is high.