Gradient method of structural heterogeneity identification in electrical inspection of equipment, products and materials

A gradient method of structural inhomogeneities identification in the objects of industrial equipment and products control based on the analysis of electric potential distribution inside a single reflex is developed. The computational and graphic method is applied to analyze the results of electrical control of NPP equipment during its manufacture. The research objective under consideration is to determine the degree of reproducibility of electrical inspection results and to develop for this purpose a universal digital identifier of structural inhomogeneities. Single reflexes are characterized by internal pressure and distribution of electric potential, which has a gradient. Single reflexes on potentiograms are isolated by electrophysical chromatography with the help of double amplitude discrimination using developed program codes. The emergence of potential distribution patterns on the surface of the controlled product is associated with the presence of inhomogeneous fields of internal stresses and deformations in it. To determine the local value of internal pressure in structural inhomogeneities, the value of energy density was estimated. This estimation for single reflexes is obtained using the value of electron density in metals and alloys. The magnitude of the gradient corresponds to the electric field strength around the reflex. On the surface, a single reflex represents a figure of concentric hexagons or other geometric figures. In the volumetric image, the reflex has the form of a pyramid with a certain figure at its base. The hexagonal shape of the reflex is associated with a quasi-equilibrium distribution of normal and tangential stresses around the point heterogeneity. The value of internal pressure in steels for the fixation level in the interval (0≤ SLS <1) is close to the strength limit, for the interval of negative values (-0,7 ≤ SLS < -0,4) – to the yield strength.