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

Provided is an eddy current inspection method which can surely detect a high-hardness portion existing locally in a magnetic metal material and surely check whether the high-hardness portion has been removed after the treatment for removing the high-hardness portion. The eddy current inspection method detects presence/absence of a locally existing high-hardness portion according to a differential signal obtained by detecting an eddy current induced in a metal material P by using a pair of detection coils (11a, 11b) and identifies the position of the locally existing high-hardness portion which has been detected, according to an absolute value signal obtained by detecting the eddy current induced in the metal material by one of the detection coils.