Patent ID: 7710111

Claim:
A nondestructive inspection method for nondestructively analyzing the position or corrosion state of a magnetic material present in the interior of a non-magnetic material structure, the method comprising: magnetizing the magnetic material from outside of the non-magnetic material structure; measuring magnetic flux density of the thus-magnetized magnetic material at the outside of the structure; defining one direction perpendicular to the magnetic material extending in an X-axis direction as a Z-axis direction and a direction perpendicular to these directions as a Y-axis direction; specifying the position of the magnetic material by determining a depth of the magnetic material in the structure through calculation from components of the measured magnetic flux density in the Y-axis direction and the Z-axis direction; and measuring the magnetic flux density of the magnetic material whose position has been specified, and measuring, in the vicinity of a magnetization point, maximum magnetic flux density which varies depending on a diameter of the magnetic material, to thereby analyze the corrosion state.