Селективный магнитный контроль толщины и степени упрочнения поверхностных слоев на стальных объектах

The dependences of measured locally magnetic characteristics of surface-hardened steel objects on the thickness and physical properties of their surface layers are studied. It is shown theoretically and experimentally that a change in the thickness of the hardened layer on the surface of steel objects affects on the magnitude of the tangential field component on the surface of the object in the interpolar space significantly , as well as the change in the strength properties of the layer affects the magnitude of the magnetic flux in the "transducer-object" circuit. It is proposed to use this difference in magnetic parameters for selective testing of the surface hardening quality. It is shown that the coercive force measured locally by the internal field and the maximum value of the magnetic flux, which can be measured using a single transducer in single measuring cycle, can be used as diagnostic parameters.

Методика практического восстановления параметров формы поверхностных двухмерных дефектов с учетом нелинейных свойств ферромагнетика

A technique for determining the depth and opening of a surface two-dimensional defect in a ferromagnet is presented, that is resistant to input data errors. Defects and magnetic transducers are located on opposite sides of the metal plate. The nonlinear properties of the ferromagnet are taken into account. The components of the magnetic field in the metal were reconstructed from the measured components of the magnetic field above the defect-free surface of the metal. As a result of numerical experiments, the limits of applicability of the method were obtained. The results of the technique have been verified experimentally.

Ультразвуковой адаптивный томограф бетонных изделий с нестандартной конфигурацией

It is shown that should be used adaptive antenna arrays, the shape of which can take the form of a non-planar surface of the tested product, for ultrasonic tomography of concrete building structures with a non-standard surface configuration. It should also be used adaptive methods of ultrasound tomography, which allows both to determine the coordinates of defects and the velocity of ultrasound in concrete, as well as adjust the parameters of the probing signals to the characteristics of concrete products.

Исследование поверхностного окисления циркония активным тепловым методом

The possibility of testing the surface oxidation of zirconium has been investigated by the method of one-way active thermal non-destructive testing based on the analysis of radiation temperatures. The emissivity of the oxidized surface of zirconium samples obtained at different annealing temperatures was estimated at various stages and heating temperatures in the infrared wavelength range. It is shown that there is a principal possibility to remotely test the oxidation process of zirconium alloys used in the nuclear industry for the manufacture of fuel elements operating in the core of nuclear reactors.

Динамическая коррекция чувствительности дефектоскопических каналов при высокоскоростном контроле рельсов

The article is aimed at increasing the reliability of high-speed ultrasonic monitoring of long-dimensional objects, in particular, railway rails. The technical documentation for the control does not take into account the features of high-speed rail monitoring, is focused on compliance with the initially set parameters and cannot provide the required reliability of defect detection. The factors that manifest themselves at high scanning speeds and negatively affect the quality of control are considered. Most of these factors cannot be quantified and accounted for in order to adjust the control parameters. An estimate of the number of undetected defects was made when working according to current documents. To ensure reliable control at high speeds, it is proposed to evaluate the current sensitivity of the control using signals from standard design reflectors of the controlled object. As such reflectors, when monitoring rails, it is proposed to use standard holes in the area of bolted joints that are regularly encountered along the scanning path. An expression is obtained for determining the value of the correction of the control sensitivity depending on the scanning speed and the measured size of the signals from the holes. An algorithm for dynamic adjustment of the parameters (sensitivity) of the control is proposed, which increases the reliability of detecting defects in high-speed scanning conditions.

Выявление магнитной анизотропии в аустенитной хромоникелевой стали после прокатки

Investigations of texture, phase composition and magnetic anisotropy in rolled samples of austenitic steel 09Kh17N5Yu were carried out. It has been shown that the method of magnetic nondestructive testing using measuring of magnetic fields from locally magnetized areas is sensitive to anisotropy of magnetic permeability. Anisotropy of magnetic properties is related to formation of mechanical rolling texture. FCC rolling texture {110}<111> was found in all the rolled samples. Rolling texture, common for BCC structure (strain-induced martensite in low-carbon austenitic steels), developed in the samples with 30% of deformation or higher. Formation of ferromagnetic strain-induced martensite in austenitic steel 09Kh17N5Yu was confirmed by magnetic force microscopy.

Особенности лазерно-виброметрического неразрушающего контроля полимерных композиционных материалов с использованием воздушно-связанных ультразвуковых преобразователей

Laser doppler vibrometry is being increasingly used in nondestructive testing (NDT) of polymer composites materials (PCM) and investigation of amplitude-frequency characteristics of acoustic transducers in a wide range of frequencies. The use of air-coupled transducers allows non- contact NDT thus expanding inspection potentials and simplifying, in some cases, test procedures, as well as reducing the environmental impact on test results, to compare to traditional techniques of acoustic NDT, which mainly implement contact stimulation of objects to be tested. In this study, the peculiarities of non-contact ultrasonic stimulation in application to NDT are analyzed by using scanning laser vibrometry. The results of NDT of impact damage in PCM are presented by using some types of air-coupled acoustic transducers, namely, magnetostrictive, piezoelectric and gas discharge.

Разработка метода ультразвукового контроля качества пластиковых изделий, полученных методом ротационного формования

At present, the technology of rotational molding of plastics is rapidly developing in the world. However, with this method of processing, it is possible for "microbubbles" to appear in the walls of the products, which significantly impair their quality. In this work, to assess the quality of plastic products, the method of ultrasonic testing (UT) was applied. Using the echo method at an operating frequency of 2.5 MHz, samples of various degrees of quality were analyzed. It was found that the propagation speed of the ultrasonic signal does not depend on the degree of product quality and is 2330 ± 10 m / s. It was found that the larger the parameter of the surface roughness Rz of the products (from 2.5 to 20 μm), the smaller the amplitude of the background signal Аа becomes. An unfinished sample is determined by the Aa parameters (from -6.0 to -15.0 MHz). A reference sample (ρ = 0.942 g / cm3) has been determined with which it is possible to calibrate the flaw detector, its Aa = 0 dB at an operating frequency of 2.5 MHz. Revealed the relationship between the density / baking of products and the amplitude of the bottom signal. The possibility of detecting internal defects of products by the ultrasonic inspection method has been proved. A new method is proposed for identifying suitable products in production, with the help of which it is possible to determine the degree of product quality.

Определение геометро-акустических свойств сварного соединения как решение обратной коэффициентной задачи для скалярного волнового уравнения

The article is devoted to the development of ultrasonic tomographic methods of non-destructive testing of objects in order to determine the geometry of a welded joint and estimate the velocity field in it. The article offers a solution to the inverse coefficient problem for the echosignal registration scheme in the mirror-shadow mode. Numerical simulations were performed for various tomographic schemes on samples with acoustic parameters and geometry corresponding to the real experiment using an antenna array with an operating frequency of 2.25 MHz. Numerical methods have been used to optimize tomographic schemes for various applied problems. It is shown that with the help of the developed tomographic schemes, it is possible not only to detect the boundaries of the welded joint, but also to determine the velocity field inside the control object.

Повышение скорости регистрации эхосигналов ультразвуковой антенной решеткой за счет оптимального прореживания коммутационной матрицы с помощью генетического алгоритма

To increase the speed of recording echo signals and increase the speed of image recovery of reflectors, it is proposed to use a thinned switching matrix (SMC). To obtain a switching matrix that allows to obtain images minimally different from the image obtained by the full switching matrix (FMC), it is proposed to use a genetic algorithm. Two variants of optimization of the switching matrix are considered: element-wise thinning and column thinning. Numerical and model experiments have shown that a thinned switching matrix determined using a genetic algorithm, filled by 25%, allows the formation of images that differ from the image obtained by FMC, with an error of about 3%. Working with the switching matrix by columns allows you to increase the speed of recording echo signals by 4 times. The speed of image recovery increases by the same number of times.