INTERNAL FLAW JUDGE METHOD BY ULTRASONIC FLAW DETECTION

摘要

PURPOSE:To certainly judge an internal flaw by discriminating a dummy echo by comparing the peak value of the echo from a distance integral multiple of the distance up to the internal flaw with the peak value of a flaw echo. CONSTITUTION:A probe 3 converts the high frequency voltage transmitted from a pulse transmission part 4 to an ultrasonic wave to allow said ultrasonic wave to be incident to a material to be inspected and the ultrasonic wave propagates therethrough a while attenuates to be reflected from internal flaws 2, 21 and returns while attenuates to be converted to voltage by the probe 3 and said voltage is displayed on an echo receiving part 5. When the internal flaw 2 is large, the ultrasonic wave is again reflected from the surface of the material 1 to be inspected to return to the probe 3 and detected as a dummy flaw echo but an echo judge part 6 compared the peak value of a flaw echo with that of the dummy echo appearing at a distance integral multiple of the propagation distance of the flaw echo and, when the peak value of the dummy echo is lower than that of the flaw echo, it is judged that there is not flaw in the region where the dummy echo is generated. When the peak value of the dummy echo is higher than that of the flaw echo, it is judged that there is an internal flaw and the flaw echo can be discriminated from the dummy echo.