Study of arrangement efficiency of hall sensors of an attachable magnetic instrument used for recording the coercive force of a local area of an article

The use as a tested parameter of a coercimeter of the demagnetizing current that is measured at the moment of zero crossing of the magnetic flux in the magnet core by Hall sensors arranged under the electromagnet poles is shown to have an advantage over the use of the demagnetizing current measured at equal readings of Hall sensors placed in the neutral plane of the electromagnet in the leakage flux at different distances from an article.     

Calculation of the induction of a constant magnetic field created in a ferromagnet by an attachable electromagnet

On the grounds of the numerical calculation of the induction of a magnetic field excited in a ferromagnet by scanners in the form of Π-shaped and solenoidal electromagnets, it is established that the Π-shaped type provides a deeper penetration of a magnetic field into a ferromagnet and its better localization in a specified volume. The induction of a magnetic field appearing under the action of a Π-shaped scanner in a ferromagnet decreased with an increase in both the thicknesses of the ferromagnet and the gap between the magnetic conductor of a scanner and the surface of a material and also depended slightly on changes in its width; a maximal scanner winding current exists, above which the induction of a magnetic field in a material changes slightly.     

Distribution of the induction of a quasi-stationary magnetic field created in a ferromagnet by an attachable electromagnet

As a result of numerical calculations, the spatial and time distributions of the induction of a quasi-stationary magnetic field, which was created in a studied ferromagnet by U-shaped and solenoidal attachable electromagnets (AEMs) at frequencies of 1 and 10 Hz, were obtained. The presence of a phase shift between the amplitude values of the magnetic-field induction at different depths in the specimen, which increases with the frequency of the exciting current, was revealed. The dependences of the magnetic-field penetration depth into the ferromagnet on the magnetic reversal frequency were studied. It was found that for the frequency range under study the magnetic-field penetration depth for both types of AEM is smaller than that for the corresponding stationary case.     

An attachable electromagnet of a coercimeter with an indicating system between the electromagnet’s poles

The dependence of the readings of a coercimeter on the gap width between an article and the poles of an attachable electromagnet (AEM) at different magnetizing and magnetization-reversing currents is studied in the case when the indicator of the magnetic state of an article is removed from the electromagnet’s magnetic circuit and placed between the electromagnet’s poles on the surface of the article. It is shown that, during coercive-force measurements, such an indicator cannot be used for determining the demagnetized state of the article in the case of substantial fluctuations of the gap between the AEM poles and the article, although it can be used for assessing the gap width.     

A permanent-magnet-based attached instrument used to inspect articles on the basis of their coercive force

An attached magnetic instrument that uses two permanent magnets to magnetize and demagnetize an article is considered. When one of the magnets is set at a fixed angle, the rotation angle of the other magnet is proportional to the coercive force of an article and is used as the tested parameter.     

Correlation of the impact elasticity of cast steels with their coercive force

The character of the correlation of the impact elasticity of cast and subsequently normalized and thermostrengthened steels 08XΓΦЛ and 08XΓTЛ with their coercive force is studied. Such a correlation in the form of a curve characterized by a maximum is observed for both low-carbon and low-alloyed hot-rolled steels.     

Vector control of induced magnetic anisotropy using an in situ quadrupole electromagnet in ultrahigh vacuum sputtering

We demonstrate the incorporation of a quadrupole electromagnet into an ultrahigh vacuum sputtering system for the vector control of induced magnetic anisotropy in magnetic thin-film heterostructures. A stationary quadrupole electromagnet is used to generate a magnetic field, which rotates synchronously with the physical axes of the substrate in situ during sputtering. An arbitrary anisotropy direction can be set for successive ferromagnetic layers by adjusting the phase difference of substrate and field rotation. The ability to rotate the substrate during deposition and change anisotropy without breaking vacuum enables the deposition of magnetically soft heterostructures with arbitrary in-plane anisotropy axes.     

The effect of a gap between the poles of an attachable electromagnet and a tested component on coercimeter readings and methods for decreasing it (Review)

The main drawback of a coercimeter with attachable electromagnets (AEM) is its sensitivity to a random gap between electromagnet poles and a tested article formed in the process of inspection. The causes of such sensitivity are analyzed and the methods for decreasing it are considered.     

Advantages of using ultrasonic chord-type probes in an elastic wear plate without a case for inspection of tube articles’ welding

Stability of the acoustic contact during use of chord-type probes of two types—(1) with and (2) without a case—to inspect ring welded joints of polyethylene tubes has been studied experimentally. The possibility of using a single probe without a case to inspect ring welded joints of metal tubes having three neighbouring diameters has been studied experimentally.     

On new possibilities for making local measurements of the coercive force of ferromagnetic objects

The possibility of reducing the influence of both the gap in a transducer-object combined circuit and the shape of tested objects on the results of local measurements of their coercive force is investigated. It is shown that additional measurements of the maximum magnetic flux in the circuit and the tangential component of the magnetic field on the surface of the tested area of the object, which is retained after the magnetizing current is turned off, allow a substantial decrease in the corresponding errors.     

A setup for measuring the magnetic characteristics of soft magnetic materials and articles

An automated setup for measuring the normal magnetization curve, the major and minor magnetic-hysteresis loops, and the main (initial permeability, maximum permeability, residual magnetic induction, induction coercive force, and saturation induction) and additional (the permeability at a field equal to the coercive force, the field strength at which the saturation induction is reached, and the induction at fields equal to the coercive force and the double coercive force) magnetic parameters of soft magnetic materials and articles produced from them is described. Measurements are performed in an open or closed magnetic circuit at a magnetization-reversal frequency of 0.05–0.5 Hz. The block diagram of the setup and its main parameters and characteristics are presented. The operation of the setup and the possibilities of its application are considered.     

Regularities of the change in the coercive force under biaxial asymmetric deformation of steel 3

The change in the coercive force under biaxial asymmetric (tension and compression in mutually perpendicular directions) cyclic deformation of cross-shaped steel 3 specimens in the elastic region of deformations was studied. Specimens were deformed beforehand under biaxial asymmetric loading to various degrees of plastic deformation. It was demonstrated that the elastic-deformation dependences of the coercive force measured along the tension and compression directions are qualitatively similar to those under uniaxial tension or compression. It was also shown that, under cyclic elastic loading, these dependences are reversible for well-annealed steel and have a hysteresis that expands with increasing degree of plastic deformation for plastically deformed steel. The possible causes of the hysteresis in the dependence of the coercive force on the elastic cyclic deformations under biaxial loading are discussed. It was supposed that the hysteresis of the coercive force was caused by the appearance of free (not bound in carbide phases) carbon atoms playing the role of interstitial impurity atoms for the α-iron lattice in plastically deformed carbon steels. The possibility of estimating the stressed-strained state of steel under biaxial loading using a magnetic method was discussed.     

Using a corrected least-squares procedure and accounting for structural parameters when analyzing the correlation between the impact strength of low-alloyed steels and their coercive force

The use of a corrected least-squares procedure that takes the error of impact-strength estimation into account, as well as several structure parameters, such as the equiaxial grain size number, Widmanstätten ferrite grain size number, and bainite percentage, allowed us to substantially improve the constraint equations between the impact strength and coercive force for a group of specimens. These specimens were sampled from no. 60 flange beams made of 09Г2 steel and exhibited no preliminary correlation between these parameters.     

Plotting and analysis of hodographs for studying the electrophysical parameters of objects using attachable eddy-current transducers

The results of experimental studies during the eddy-current testing of conducting (including ferromagnetic) objects are considered. A data correcting procedure was suggested; it allows one to decrease the requirements for the phase and frequency stability characteristics of the measuring circuit and to relate experimental results to a theoretic model. Initial and corrected hodographs for a number of materials with different electrophysical properties are reported. The magnetic permeability magnitudes of steel 30X13 were calculated for two electromagnetic-field exciting frequencies (15 kHz and 1 MHz).     

Study of the field around magnetic force microscopy probes using electron holography

We have used electron holography to perform quantitative investigations of the leakage flux of thin film tips used as probes in magnetic force microscopy. A method to deduce an arrangement of magnetic domains in a thin magnetic whisker from the knowledge of the stray flux is also described. A simple analytical model of the magnetic properties of the probes allows the extraction of computer images, which simulate the experimental results satisfactory. The reliability of the recorded experimental maps of the magnetic flux arising from these kinds of sensors allows an evaluation of the total flux affecting the sample and the calculation of the magnetic field profile along the tip axis.     

Optimization of the magnetic circuit in the MFL inspection system for storage-tank floors

Magnetization is the key to inspection of a tank floor via the magnetic-flux-leakage (MFL) technique. In order to optimize the magnetic circuit of the MFL detector and obtain the best detection effects, the influences of the magnet size on the floor magnetization condition, the gap magnetic flux density, and the magnetic force were studied with the help of the finite element method (FEM) and the effects of some other parameters, such as the magnet pole spacing and pole-piece thickness, on the signal-to-noise ratio were analyzed. The simulation results indicate that variation of the magnet width affects the magnetization much more than variation of the magnet thickness and that the detector can reach a trade-off between the magnetization effects and the driving force when the magnet is about 30 mm thick and 40 mm wide. On condition that the floor has reached its magnetizing saturation, an increase in the magnet-pole spacing and the pole-piece thickness can improve the testing sensitivity and the signal-to-noise ratio. The text was submitted by the authors in English.     

磁芯模具的安装与压制模拟研究

建立磁芯模具安装及压制模型 ,提出坯件压制模拟算法。利用该算法可对模具的安装及压制进行模拟 ,从而为模具的实际安装提供有价值的数据 ,节省了调整模具的时间。     

Automated visual inspection for surface appearance defects of varistors using an adaptive neuro-fuzzy inference system

The purpose of this study is to develop an automated visual inspection system for analysis of the surface appearance of ring varistors based on an adaptive neuro-fuzzy inference system (ANFIS). Known image patterns of the six types of ring varistors are used in a training process to establish Sugeno FIS rules, and the input-output data are then set to train the ANFIS to tune the membership function. Feature extraction reduces image complexity using two-dimensional edge detection, calculated within divided rectangular region. The ANFIS combines the neural network adaptive capabilities and fuzzy logic qualitative to train a classification system for six different types of components. The performance of the ANFIS is evaluated in terms of training performance and classification accuracy. The results confirm that the proposed ANFIS is capable of classifying the six types of ring varistors with an accuracy of 98.67%. This paper has not been published elsewhere nor has it been submitted for publication elsewhere.