Ultrasonic flaw detection method, ultrasonic flaw detection apparatus, and pipe material manufacturing method

摘要

To provide an ultrasonic flaw detection method, an ultrasonic flaw detection apparatus, and a pipe manufacturing method that can detect even dent flaws or shallow flaws in a lapped form arisen on inner surfaces of metallic pipes such as steel pipes, included are a wave memory 11 that acquires and holds waveform data of an echo signal when an ultrasonic probe 2, generating ultrasonic signals toward an inner surface B of a steel pipe 1, and the steel pipe 1 are moved relative to each other; a signal analyzing unit 12 that calculates a path length up to receiving an echo signal from the inner surface B and a change rate of the path length based on the waveform data held; and a flaw detector 13 that detects a flaw BW on the inner surface B based on the path length and the change rate of the path length.