| 摘要 |
PURPOSE: To obtain an ultrasonic flaw detection method to defect flaw in a material to be inspected in such manner that the material to be inspected is sandwiched between the transmitting part and the receiving part of ultrasonic waves, Bl waves and B2 waves of the ultrasonic waves which have passed through the material to be inspected are received by the receiving part and the ratio of the echo height of the B1 waves to the echo height of the B2 waves is found. CONSTITUTION: A material 14 to be inspected is sandwiched between leg parts 12, 13 for a frame 11, and ultrasonic waves are emitted toward a receiving probe 16 from a transmitting probe 15 by means of a water permeation system. The receiving probe 16 receives ultrasonic waves which contain B1 waves having passed directly through the material 14 to be inspected and B2 waves which have gone back and forth once due to reflection inside the material 14 to be inspected. When a flaw such as cast pore$ or the like exists in the material 14 to be inspected, the height of echoes by the B1 waves and the B2 waves is lowered, and the flaw can be detected. Whether the material 14 to be inspected is good or not is judged by a definite threshold value. The ratio of the height of the B1 waves to that of the B2 waves is computed by an expression of Bdiv=C×H2/H1×100(%), where H1 represents the value of the echo height of the B1 waves, H2 represents the and value of the echo height of the B2 waves and C represents the value of H1/H2 in a sound material. |
