ULTRASONIC FLAW DETECTION APPARATUS

PURPOSE:To form the image at the desired part of an object to be inspected to display the same, by operating the locus which is supposed to be present as a flaw detection signal generation source from the time information of a flaw detection signal to a plurality of oscillating angles, and cumulating and adding the intensity information of the flaw detection signal on the operated locus. CONSTITUTION:When the flaw detection of the point B of a key groove is performed by a pitch and catch method, the route of ultrasonic beam reaches B from the transmission point T on the surface of a web 21 and further reaches the receiving point R on the surface of the web 22 in the opposite side. The time (t) required in propagating ultrasonic wave through TBR is measured and converted to a rotary radius PB=r of a probe 5 or 6. Next, when the circular arc of the above-mentioned converted radius (r) is drawn around the point P, wherein the positions of the probes 5, 6 were projected to an A-A surface, on the basis of a flaw detection signal, said circular arc comes to the locus showing the presence position of the reflective source present at the key groove part B. If this locus is drawn at every positions P1, P2... of the probes 5, 6 scanned on one circumference of circle and a receiving signal is weighted, a circular arc locus group is formed at every reflective source and the intersecting point thereof forms the image of the reflective source.