Magnetic effects in eddy current nondestructive method are studied employing an extension of the general ideas of Globus for the magnetization processes of polycrystalline materials. The reversible permeability depends on the residual magnetization of the material. The relation between these two quantities is derived from the Globus model. An expression is derived for the impedance of a single‐turn coil above a ferromagnetic conducting half‐space. From this expression, flaw effects and liftoff effects are analyzed, and theoretical treatment for the evaluation of residual magnetization is described.