| 摘要 |
PURPOSE:To make it possible to compare and detect the sizes of internal defects based on the magnitues of detected signals regardless of the distance from a flaw detecting point to the defect by amplifying the amount of attenuation of an ultrasonic wave after the incidence, and correcting the detected value of the reflected wave. CONSTITUTION:At the time of flaw detection, an exciting signal is inputted into a probe 4 from a flaw detector 9. The probe 4 oscillates the ultrasonic wave in response to the exciting signal. The ultrasonic wave is applied into a steel material 6 at 45 deg. with respect to the normal line of the continuously case round steel material 6 within the axial cross section through the water in a probe holder 7. The incident ultrasonic wave is reflected by the surface scattering, surface defects and inner defects at the steel material 6. The reflected strength signals are received with the probe 4 and inputted into the flaw detector 9. In the flaw detector 9, the reflected strength signals are gated, and only the signals caused by the defects located at a place deeper than a specified depth from the surface of the steel material 6 and the signals having the preset sensitivity or more are extracted. The amplification factors are computed with a computer 14 for the extracted signals. The amount of attenuation of the reflected strength with time is corrected. |
