| 摘要 |
PROBLEM TO BE SOLVED: To provide a method an device for detecting the flaw of the internal defect of the diffusion surface of a metal material with high sensitivity. SOLUTION: By using a double-probe-type flaw detector with transmission and reception probes, ultrasonic waves are directly applied to a junction surface to be diffused at 45 degrees, and a reflection wave being reflected once on the surface of a material whose flaw is to be detected is captured while changing the distance between the two probes. The transmission and reception probes where an interval is variable are mounted to a pedestal with a bottom surface of the same curvature as that of a pipe diameter, and a support roller, a permanent magnet, an encoder, and signal wiring made of a shape storage alloy are mounted, thus providing the ultrasonic flaw detector for inspecting steel pipe for easily detecting the flaw without causing the rear surface of a thin steel pipe to fall off. |
