A method for measuring the size of a defect in a ferromagnetic product and a device for its implementation

• Main Authors: Shleenkov, A. S., Shleenkov, S. A., Kukovenko, A. V., Pastukhov, A. B., Gubanov, Y. V.
• Format: Conference Proceeding
• Language: English
• Subjects: Ferromagnetism; Field strength; Magnetic induction; Magnetic permeability; Measurement methods; Measurement techniques; Scattering; Surface defects; Topography
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0089252

A method of determining the geometric parameters of surface defects in ferromagnetic products from the experimentally recorded topography of the tangential component of the magnetic stray field strength was developed. To measure the depth of the defect the product is magnetised by a constant magnetic field and the amplitude of the tangential component of the scattering field of the defect is measured. Then points are found where the defect field is independent of the measurement height and the defect depth is judged by its magnitude. The accuracy of defect sizing is improved by eliminating the influence of the gap between the sensor and the product under test on the measurement results. When determining the defect width, a measurement technique similar to the one used to determine the defect depth is used. The topography of the tangential component of the magnetic stray field induction above the defect is recorded with an arbitrary probe trajectory, i.e. independent of the gap. The magnetising field is subtracted from the topography, but the area under the resulting curve of the tangential component of the scattering field above the defect is also found, and the value is then divided by the product of the magnetic permeability of the material and the magnetising field.