Abstract: A non-destructive inspection includes: magnetizing a target by a first magnetostatic field (S2); shutting off the magnetostatic field (S3); measuring, at measurement points, the transient change of a differential magnetic flux density of a first residual magnetic field of the target (S4); obtaining a first time constant by the main time constant of the transient change at each measurement point (S5); magnetizing the target by a second magnetostatic field (S2); shutting off the second field (S3); measuring, at the measurement points, the transient change of a differential magnetic flux density of a second residual magnetic field of the target (S4); obtaining a second time constant by the main time constant of the transient change for each measurement point (S5); and obtaining information about the internal structure of the target by the distribution differences between the first and the second time constants at the measurement points (S7).

Abstract: A non-destructive inspection device (X1) includes an exciting pole (10) having a magnetic flux exciting surface (11) for exciting a magnetic flux to form a magnetic field in an inspection target, a recovering pole (30) having a magnetic flux recovering surface (31) for recovering the magnetic flux excited from the magnetic flux exciting surface (11), and a coil array (50) having a plurality of loop coils though which the magnetic flux excited from the magnetic flux exciting surface (11) passes prior to reaching the inspection target, the coil array being offset toward the recovering pole (30) with respect to the magnetic flux exciting surface (11).

Abstract: The process first applies a magnetostatic field to a target magnetic body to magnetize the target magnetic body. The process then cuts the magnetostatic field off and measures a transient variation in a differential magnetic flux density at a plurality of positions in the vicinity of the target magnetic body. The process subsequently determines a time constant of the transient variation in the differential magnetic flux density at the plurality of positions. The process then determines a specific characteristic value relating to the internal structure of the target magnetic body, based on a distribution of the time constant over the plurality of positions. This arrangement enables a variety of internal structures of the target magnetic body to be examined in a non-destructive manner.