INSPECTING DEVICE FOR METALLIC MATERIAL

摘要

PURPOSE:To inspect the nonuniform metallic structure of an object of inspection by detecting the ratio of received echo signals passed through a band-pass filter which allow signals of two frequencies about an oscillation ultrasonic wave frequency to pass. CONSTITUTION:An ultrasonic wave incident on the object 10 of inspection through an ultrasonic wave probe 20 is received again by the ultrasonic wave 20. Wide-band frequencies having a center frequency f0 are used for the ultrasonic wave applied to the ultrasonic wave probe 20. An ultrasonic flaw detector 30 input received signals to band-pass filters 40 and 50 for frequency components corresponding to half-value widths shown by f1 and f2 through a circuit which passes only signals received until the bottom surface echo of the object of inspection is received. Output signals of the filters 40 and 50 are inputted to a divider 60, whose output signal is inputted to a recording and alarm generating part 70 to detect nonuniform structure in the object of inspection. The division result is almost 1 when the structure is uniform, but when the ultrasonic wave strikes structure having a small grain boundary, the ultrasonic wave echo signal of the high frequency side increases relatively.