EDDY CURRENT INSPECTION METHOD, STEEL PIPE INSPECTED BY THE EDDY CURRENT INSPECTION METHOD, AND EDDY CURRENT INSPECTION DEVICE FOR CARRYING OUT THE EDDY CURRENT INSPECTION METHOD

摘要

It is an object of the present invention to provide an eddy current testing method capable of securely detecting a high hardness part locally occurring in a metal material having magnetism, and capable of securely checking whether the high hardness part has been removed after execution of a repairing treatment for removing the high hardness part. In the eddy current testing method according to the present invention, a frequency of the AC current for energizing the differential coil 1 is set so that a phase difference between a magnetism variation signal of the metal material P and a liftoff signal detected by the differential coil is equal to or larger than 135°, and a local high hardness part occurring in the metal material is detected based on an amplitude and a phase of a detection signal outputted from the differential coil.