ULTRASONIC FLAW DETECTION DEVICE, ULTRASONIC FLAW DETECTION METHOD, METHOD OF MANUFACTURING WELDED STEEL PIPE, AND WELDED STEEL PIPE QUALITY CONTROL METHOD

摘要

An ultrasonic flaw detection device 1 includes: a matrix array probe 2 that is arranged, via a wedge 3, at a position on a outer peripheral surface of a welded steel pipe S, the position enabling ultrasonic waves to be vertically incident on a welding root surface, transmits ultrasonic waves focused in a pipe axis direction, to the welding root surface, and receives ultrasonic waves reflected at the welding root surface; an ultrasonic wave transmitting and receiving unit 4 that controls the matrix array probe 2 such that the matrix array probe 2 receives the reflected ultrasonic waves reflected at the welding root surface; and an evaluation unit 5 that detects a planar defect based on the reflected ultrasonic waves received by the ultrasonic wave transmitting and receiving unit 4.