The article is devoted to the results of a laboratory and industrial study that shows that the suggested criterion can be used as an integral diagnostic parameter of the state of new and old (operating) parts made of a ferromagnetic material. The main criterion in diagnosing the equipment by the method of magnetic memory of the metal is the determination of the zones of stress concentration (SC) on the surface of the controlled part, which are characterized by changes in the sign of the field of residual magnetization H~: or a line on the surface characterized by a zero normal component of the field H~:. The field H~: is measured by a special IMNM-1F magnetometer produced by the t~nergodiagnostika Research and Production Association.It is known that the stress concentration zones are the main sources of the development of damage where the processes of corrosion, fatigue, and creep progress intensely. Zones of stress concentration appear due to the known law of energy conservation. In the production of any ferromagnetic part the mechanism of appearance of the actual magnetic texture occurs under the conditions of simultaneous action of the magnetic field of the Earth (at the least) and changes in the internal stresses. An energy transfer occurs between neighboring layers of the material, and zones where residual stresses are concentrated appear depending on the structure of the metal, the process technology, the heat treatment, and the magnetostriction.The texture of ferromagnetics with a positive magnetostriction stretches in the direction of the vector of the external magnetic field and compresses in perpendicular directions. If the strain develops unhampered in this case, cracks should appear inside the part. In actual practice the constant of magnetostriction is low and cracks do not emerge, but the internal elastic energy grows considerably. In order to oppose this, the domains in which the magnetization vectors are parallel to the external field H e grow in volume, and the deformation of the whole part is determined by the magnetostriction of the principal domains. Individual domains in parts with a nonuniform structure are fixed on defects of the crystal lattice.Knots of fixed domains appear in places with the highest concentration of defects and impurities in the presence of an external magnetic field and form a total demagnetizing field of defects passing onto the surface of the part in the form of magnetic scattering fields. The normal component of this scattering field H v at the place of the maximum inhomogeneity of the metal structure changes sign and acquires a zero value, whereas the tangential component H~: that coincides with the direction of the internal magnetic field has a maximum value. When the surface of the part is scanned, the places of maximum inhomogeneity of the structure are characterized by the line describing the changes in the sign of the field H~ that can be easily measured by a magnetometer.It has been assumed that the line H~ = 0 determined in this way on a ferromagnetic part aft...
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