MAGNETIC FLAW DETECTING METHOD AND MAGNETIC FLAW DETECTION DEVICE

摘要

A magnetic flaw detection device (100) is provided with a magnetizing means (1) which causes a rotating magnetic field to act on a material to be inspected, a detection means (2) which detects flaw detection signals, and a signal processing means (3) which subjects the flaw detection signals to signal processing.  The magnetizing means supplies alternate currents, as exciting currents, obtained by superimposing a first current and a second current of a lower frequency than the first current.  The signal processing means is provided with a first synchronous detection means (31) which synchronously detects the flaw detection signals with the first current as a reference signal, a second synchronous detection means (32) which synchronously detects outputted signals from the first synchronous detection means with the second current as a reference signal and extracts flaw candidate signals, and a flaw detection image display means (34) which displays flaw detection images wherein respective pixels have densities according to the intensities of the flaw candidate signals at the respective sections of the material to be inspected, so that the phases of the flaw candidate signals at the respective sections can be identified.