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In this paper, the magnetic properties of non-oriented (NO) and grain-oriented (GO) silicon steels with dc-biased induction are measured and analyzed within the wide range of 20–1000 Hz, 0–1.9 T. While by the physical method, we found that all the ac-, dc-, and dc-biased fields do not influence the electrical resistivity of silicon steel, and hysteresis loss is mainly responsible for the iron loss increase when dc-biased induction exists. With the frequency and ac induction going up, the effect of dc-biased induction on iron loss will become weak. Compared with NO steel, iron loss of GO steel is more sensitive to dc-biased induction. The validation shows that existing iron loss models which claim to consider dc-biased magnetic induction are not satisfactory up to now when applied in the wide range of dc-biased induction, ac induction, and frequency. [ABSTRACT FROM AUTHOR]

Highlights • Low field magnetic permeability up to Curie point reported for ferrite-pearlite steels. • FE microstructure model to predict permeability-temperature relationship developed. • Excellent agreement between modelled and measured data for ferrite-pearlite steels. • Model can predict permeability-temperature data for ferrite-austenite microstructures. Abstract The magnetic properties of steels are sensitive to temperature and currently the only way to determine them is by experimental measurement. In this work a cylindrical shaped ceramic cored EM sensor has been used to measure the low magnetic field inductance of pure iron and C-Mn steels with ferrite + pearlite microstructures during heat treatment up to 800 °C in a furnace. The low field relative permeability values have been determined by fitting the sensor readings to a finite element sensor model generated in COMSOL, where the model has been validated for room temperature measurements using samples of known low field relative permeability. The low field relative permeability values with temperature follow the expected trend of increasing values with temperature, particularly close to the Curie temperature. The measured low field relative permeability values for the mixed ferrite + pearlite microstructures have been compared to predicted values from an FE microstructure-permeability model using the single phase (ferrite or pearlite) low field relative permeability values as input. The model predictions agree well with the experimentally measured values allowing any two-phase ferrite + pearlite microstructure low field relative permeability with temperature relationship to be determined. The model has also been used to determine the low field relative permeability of ferrite + austenite microstructures with temperature. [ABSTRACT FROM AUTHOR]

Laminations of non-grain-oriented (NO) electrical steel grades for magnetic cores of electrical machines should feature homogenous magnetic properties within the entire sheet plane. Basic empirical models have been introduced to estimate and correlate magnetic properties with microstructural material parameters. In these considerations, the steel sheets are generally considered to be homogenous, i.e., orientation dependence and variations across the sheet thickness are often disregarded. Whether or not, these simplifications are justified and how grain size and texture are described most suitable for correlations with magnetic properties is the focus of this paper discussing four industrial NO steel grades. [ABSTRACT FROM AUTHOR]

This work investigates the microstructure and texture evolution in grain-oriented electrotechnical steel with a new inhibition system based on vanadium carbides nano-particles. The novel approach for the preparation of this steel with appropriate final magnetic properties combines not only nanoinhibitors based on the vanadium carbides precipitations but also includes strain-induced grain growth mechanism in combination with dynamic continuous annealing during the secondary recrystallization. The experimental grain-oriented steel with proposed new chemical composition was prepared in laboratory conditions. The texture analysis has shown that suggested procedure led the formation of sufficiently strong {110}<001> Goss texture during the short time period of a final annealing process, which is comparable to that obtained in the conventionally treated grain-oriented steels. [ABSTRACT FROM AUTHOR]

Nowadays, optimization of non-oriented (NO) electrical steels toward lower iron-loss, improved, and isotropic magnetizability is critical to the improvement of rotating electrical machines. The whole production process chain adjusts the microstructure evolution, e.g., grain size and crystallographic texture, determining the magnetic properties. In particular, the interdependence of raw material properties and the resulting mechanical stress distribution during final assembly, e.g., punching, leading to magnetic property deterioration is crucial for the optimization of NO steel properties of rotating machines. This paper studies the effect of different cold rolling strategies, annealing treatments, and sheet metal blanking (punching) regarding microstructure evolution, magnetic properties, and deterioration. [ABSTRACT FROM AUTHOR]

A method for the monitoring of residual stress distribution in steels has been developed based on non-destructive magnetic permeability measurements. The dependence of differential permeability on residual stresses induced through a controlled process of applied tensile and compressive stress in the elastic region, of all three zones of the welded metal, yields the magnetic stress calibration curve (MASC). MASC is obtained on flawless welded steel plates and can be measured for any grade of ferromagnetic steels. A surface MASC correlates the magnetic permeability with the spatial stress distribution, as determined by the X-Ray Diffraction Bragg-Brentano diffraction. A bulk MASC correlates the bulk magnetic permeability with residual stresses, as determined by the neutron diffraction. The resulting calibration curves, obtained for several grades of ferromagnetic steels, have a sigmoid shape but are unique for each grade of steels. Normalizing the magnetic permeability and the stress values against the differential permeability measured at the yield point and yield stress, respectively, the dependence of the local magnetic permeability on residual stresses for all different tested grades of steels results in a universal curve relating magnetic and elastic properties of steels at the macroscopic level. [ABSTRACT FROM AUTHOR]

A methodology to evaluate the anisotropy of magnetic properties of grain-oriented steel sheets is presented. The approach is based on the orientation distribution function (ODF) theory. The existence of sheet symmetry and orthorhombic symmetry of body-centered cubic iron crystal is discussed with ODF. As a result, in order to characterize the magnetic properties, it is sufficient to carry out measurements for three directions, since the evaluated property is directly related to the magnetocrystalline anisotropy. The presented approach may be a useful tool for the designers of magnetic circuits in electrical machines. [ABSTRACT FROM PUBLISHER]

This paper develops an approach to evaluate and predict the effect of punching processes upon the performance of switched reluctance motors (SRMs). Punching is a common process for manufacturing of electric motors although the magnetic performance of the electrical steels at the cut edges may degrade. This could then result in a lower motor performance than expected. Annealing can usually restore the material property but it would be costly for production of common electric motors. Therefore, it is useful to compensate this effect in the design of electric motors. In this paper, the damaged range due to punching is modeled and included in the finite-element simulation for the SRMs such that the effect of this damage can be evaluated. The material properties at the cut edges are determined using the techniques developed here. Two SRMs are investigated: one being annealed after punching and the other not before assembly. Test results show that the annealed SRM produces a better performance. The comparison between the simulations and experiments shows that the developed method can be used for analysis of punching effect on motor performance. [ABSTRACT FROM AUTHOR]

This paper shows that there is strong dependence of saturation magnetization on the alloying content in ferromagnetic steels. This dependence was used to determine the cross-sectional areas of the commercial non-oriented and grain-oriented silicon–iron steels. The relation between magnetization near saturation and the contents of silicon and aluminum for a large number of steel samples was experimentally obtained using an air-cored magnetizing system. The influence of the approach to magnetic saturation and its use in the determination of the cross-sectional area of electrical steel strips using the saturation magnetization method was estimated. Standard deviation (SD) of cross-sectional area obtained using the saturation magnetization method was on the order of 0.14%. SD for using conventional technique was also on the similar order of $\sim 0.11$ %. [ABSTRACT FROM PUBLISHER]

In this paper, two identical American Iron and Steel Institute 1008 steels sheets were welded together in a butt joint configuration, with the welding line direction parallel to the rolling direction. The sheets were welded using the electron-beam welding technique. Stress distribution was monitored in the surface and the bulk of the welded samples using X-ray Bragg–Brentano and neutron diffraction methods, respectively. Accordingly, surface and bulk magnetic properties, namely magnetic Barkhausen noise and quasi-dc permeability, were monitored in the same area. Both surface and bulk magnetic measurements exhibit good agreement with the surface and bulk stress measurements obtained by the diffraction methods, after a proper calibration procedure. Complementary measurements with scanning electron microscopy and Vicker’s microhardness tester provide similar good agreement between the microstructural characterization and the residual stress distribution. [ABSTRACT FROM AUTHOR]

The effect of various combinations of conditions, i.e., presence of the Earth's magnetic field during and after deformation on the distribution of stray magnetic field of S355 steel sample, which is locally deformed, was investigated. Some of the stages of the experiment were carried out in zero magnetic field. Compensation of the Earth's magnetic field was obtained by the application of a pair of Helmholtz coils. These coils are able to produce homogeneous field compensating Earth's magnetic field over the full length of the sample. Stray magnetic field measurements were carried out along the longest dimension of the sample using the probe consisting of mutually perpendicular sensors allowing the simultaneous measurement of two magnetic field components, i.e., tangential and normal to a surface of the sample. Research has shown that there is a correlation between the level of plastic deformation of the investigated sample and the distribution of stray magnetic field. It was found that the nature of stray magnetic field of the sample depends on presence of external magnetic field during unloading. An attempt was also made, with the finite-element analysis, to verify experimentally obtained stray magnetic field distribution of undeformed sample. [ABSTRACT FROM AUTHOR]

Magnetic properties of nonoriented electrical steel sheets are influenced by mechanical stress because they exhibit the phenomenon of magnetostriction. Therefore, it is necessary to clarify the relationship between magnetic properties and magnetostriction under mechanical stress. This paper presents the results of measurements of the vector magnetic properties and the magnetostriction of a nonoriented electrical steel sheet under biaxial stress. The loci of the magnetic field strength vector and the 2-D magnetostriction are measured under both biaxial stresses. The magnetic power loss and the peak-to-peak value of the magnetostriction in an arbitrary direction decreased due to the applied biaxial tensile stress. It can be concluded that it is possible to improve the magnetic properties and reduce the magnetostriction of an electrical steel sheet by applying biaxial tensile stress. [ABSTRACT FROM AUTHOR]

Because electric cars are manufactured in high quantities, the influence of punching of nonoriented electrical steel with respect to tool wear becomes an important topic for the automotive industry. With regard to quality assurance, it is necessary to investigate the local degradation of the magnetic properties due to the plastic deformation caused by the cutting process. In this contribution, both the local changes of the microstructure of the material and the magnetic properties will be considered. Different methods for analyzing the manufactured electrical steel laminations were applied. Cutting edges generated under different states of tool wear were examined by means of optical microscopy and electron backscatter diffraction to visualize the influence of plastic deformations. The magnetic properties of punched electrical steel laminations as a function of increasing tool wear have been determined by hysteresis measurements of stacked ring cores. With respect to quality assurance purposes spatially resolved measurements have been carried out to determine local magnetic properties and find a suitable correlation to application-relevant quantities. [ABSTRACT FROM AUTHOR]

We report on novel approach for the abnormal growth of Goss grains that employs the system of VC nano-precipitates in combination with a phenomenon of the deformation induced grain growth. The laboratory slab of grain oriented steel was subjected to hot rolling with reduction of the thickness of sheet to 2.2 mm. The influence of coiling temperature on the distribution of VC particles was analyzed by TEM. The obtained results have confirmed the presence of VC nanoparticles with a typical size of 5–15 nm located preferentially in the vicinity of grain boundaries. Subsequently, the hot rolled strips were subjected to the cold rolling with the reduction \varepsilon \sim 84\\%, followed by primary recrystallization, temper rolling and final annealing in dynamic conditions at 1050 ^\circC. This procedure led to evolution of the sufficiently strong \110\\langle 001\rangle Goss texture, which follows in the soft magnetic behavior comparable to that obtained in the long-time heat treated industrial GO steels. Thus, the proposed approach allows reach the equal material's quality at significantly shortened manufacturing time and lower energy consumption as compared to the conventional process of GO steel fabrication. [ABSTRACT FROM AUTHOR]

In order to eliminate errors that result from different properties of a calibration sample and a tested object when selecting the conditions for an eddy-current inspection, the electric and the magnetic properties of various steel grades were investigated that are necessary to analyze the positions of the hodographs on the flawless areas of the calibration sample and the test object and to make corrections for the expected changes in these properties that are caused by the effects of a gap for defective areas of a tested object. The study was carried out using samples that were manufactured of steel grades of different chemical compositions with a set of artificially made defects of known sizes. The test technique was evaluated on the basis of a reference specimen from D16 duralumin. The magnetic and electrical properties of the steel grades that are necessary to calculate the hodographs of the signals from the transition-type and lay-on eddy-current converters and to select test conditions are reported. [ABSTRACT FROM AUTHOR]

AC magnetic properties of electrical steel sheets are generally evaluated under symmetrical alternating magnetization in the standard magnetic measurement. However, magnetizing conditions of electrical steel sheets in electromagnetic machines are not always symmetric and alternating magnetization. This paper presents a new measuring system for AC magnetic properties of electrical steel sheets under two-dimensional DC-biased magnetization and discusses the properties under DC-biased magnetization. [ABSTRACT FROM PUBLISHER]

Magnetic Barkhausen Noise (BN) is a useful parameter for analysing physical and micro structural properties of electrical steel. It is believed to be due to microscopic discontinuities in domain wall motion due to the presence of defects. Grain-oriented electrical steel has an insulating surface coating which provides a beneficial stress in the steel. BN is sensitive to changes in the surface condition of steels. Measurements have been carried out on strips of high permeability grain-oriented (HGO) and conventional grain-oriented (CGO) 3% silicon steels, at 50 Hz in the peak flux density range 8.0 mT to 1.0 T before and after chemical removal of the coatings. Coating removal from HGO and CGO materials increases BN at high and low fields. This can be explained in terms of widening of 180^\circ domains due to the release of coating stresses so that domain walls move further between pinning sites thereby generating higher rates of change of magnetisation which result in higher BN. In the coated materials, BN was found to be higher in HGO than in CGO at flux densities above around 0.2 T but the trend changes at lower flux densities because of grain size/misorientation effects. However, it is interesting to note that in the decoated material the BN is higher in HGO at all flux densities. Application of a 3 MPa tensile stress to the decoated samples caused the BN below 0.2 T to become higher in CGO than in HGO demonstrating that domain refinement due to coating stress and externally applied stress produce similar effects on BN. A significant correlation was found between the average velocities of domain wall movement and changes in BN at all the peak flux densities in the test materials. [ABSTRACT FROM PUBLISHER]

The influence of the tile angle of the [001] out of crystal surface \beta on iron loss improvement of 3 % Si steel single crystals was investigated. This iron loss improvement was caused by tensile stress effect of TiN coating and domain refinement. When \beta angle was less than 3 degrees, both eddy current loss and hysteresis loss decrease. Extremely low iron loss was obtained, when \beta angle equal to about 2 degrees. On the other hand, when \beta angle is more than 3 degrees, the hysteresis loss increased though the eddy current loss decreased by TiN coating. As a result, change in iron loss was small after TiN coating and domain refining. Therefore, it was clarified that the iron loss improving methods, such as domain refining and ultra-high tension coating, were effective especially in grain oriented electrical steel whose \beta angle is less than 3 degrees. [ABSTRACT FROM PUBLISHER]

Changes of magnetic and mechanical properties by high-temperature, isothermal agings were studied in a 12Cr-W steel. Results of coercivity, hysteresis loss, and Vickers hardness obtained from the aged specimen decreased with second order exponential functions of the aging time increased. These phenomena were analyzed using the scanning electron microscope, backscattered electron, and X-ray diffraction; from a microstructural viewpoint, the aging resulted in a coarsening of the tempered carbide (Cr23C6) and a formation of the Laves (Fe2W) phase. These microstructural changes are closely related with a reduction of the mechanical strength with the aging time. [ABSTRACT FROM PUBLISHER]

The simultaneous effects of the hot band grain size and cold reduction on the final grain structure, texture and magnetic properties of 3%Si steel were studied by variation of finishing temperature and hot band thickness during hot rolling, followed by cold rolling to final thickness and annealing in H2/N2 atmosphere. The results have shown that there is an optimum combination of hot band thickness and hot band grain size for maximum Eta/Gamma ratio and better magnetic properties (B50 and W1.5/60) after final annealing. For the thicker hot band, it was observed that higher finishing temperature, or larger hot band grain size, was necessary to achieve high Eta/Gamma and better magnetic properties. Too large hot band grain size, however, could result in smaller final grain size due to the intense nucleation on recrystallization in the shear bands and consequently poor core loss values. This behavior was explained based on the hot band grain structure and cold rolling effects on the texture evolution. [ABSTRACT FROM PUBLISHER]

To describe the vector magnetic hysteresis phenomenon of electrical steel sheets, an improved vector Jiles-Atherton hysteresis model is presented. The proposed model is developed based on Berqvist model. First, the anhysteretic magnetization function is improved by modifying the model parameters according to the excitation direction. By this, the modeling results are accurate under different alternating and nonsaturated rotating excitations. Furthermore, to model the magnetic property under saturated rotating excitations accurately, the proposed model is extended by modifying the model parameters according to the measured data. The proposed model is validated through comparisons between modeling and measured results under different alternating and rotating excitations. [ABSTRACT FROM AUTHOR]

The magnetic Barkhausen noise (MBN) in JRQ reference steel was measured under varying magnetization rate. The scaling properties of the avalanche size distribution were determined experimentally as a function of the excitation frequency. We have found that the exponent decreases and the scaling region extends as the excitation frequency increases in accordance with theoretical expectations. The average avalanche energy, size, and frequency were found to have power law dependence on the excitation rate. The temporal analysis has shown that the MBN noise generation starts earlier and develops a more symmetric character with the increase of the excitation frequency. These changes with the excitation rate can not be accounted for only by the overlap of individual MBN avalanches, but reveal a change of the dynamics of the MBN process. [ABSTRACT FROM AUTHOR]

Abstract: Case depth measurements of surface-hardened steel parts are important for quality control. Here, the magnetic properties of two sets of carefully characterized 25-mm-diameter case-hardened steel rods were studied with the aim of developing new methods to evaluate the case depth nondestructively. Induction-hardened 4140 steel and carburized 8620 steel rods were studied. Each set contained control samples (heat-treated but not surface-hardened) and samples hardened to three different nominal depths. After fabrication, the microhardness profiles of the rods were measured and the data analyzed to obtain the mid-hardness depth in each case. These measurements were compared with optical micrographs that reveal the microstructure of the samples as a function of depth below the surface. By the analysis of measured magnetization curves and hysteresis loops, the differential permeability and saturation magnetization of the rods were extracted. It was found that differential permeability increases with increasing case depth at a certain strength of the applied field (1350–1450A/m) for both hardening mechanisms, but only significantly for induction-hardened rods. Saturation magnetization was evaluated using the ‘law of approach’ and was observed to decrease as the depth of case hardening increases, for both induction-hardened and carburized steel rods. The observed behavior is described adequately by a simple model in which for the rod is represented as a volume-weighted sum of saturation magnetization values in the core and in the surface layer. [Copyright &y& Elsevier]

Angular dependent magnetic Barkhausen noise energy signal measurements were performed on two similar pipeline steel samples up to tensile stresses of 330 MPa. Variations between the stress dependence of the energy signals at five investigated positions were interpreted in terms of the relative proportion of three stress-dependent mechanisms for modifying the magnetic properties of steel. These were; the change in the number and in the orientation of 180/spl deg/ domain walls and the modification of pinning barriers. [ABSTRACT FROM PUBLISHER]