The defect parameters can be evaluated by defect induced magnetic field topography using Hall sensor. Investigations were carried out on specially prepared samples with artificial defects. According to calculations and tests tangential component of magnetic field strength extremes were detected values on either side of the defect in the surface layer l only. But this effect can not be detected by Hall sensors or Foerster probes due to their sizes. The normal component of the magnetic field strength provides a sufficiently accurate determination of the fault location, where this component becomes zero between the two extreme values located quite close to each other. The results of the study showed that at distances available to Hall transducers one can confine to the experimental research, whereas computational methods shall be used to study the topography of field defects at very small distances from the surface. This could open the prospects for testing at small distances from the surface of the object.
flux density, magnetic-field strength, magnetic-field topography
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