Search

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]

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]

The magnetic characteristic of magnetic steel sheets used for rotating machines can be degraded by punching, cutting, or other manufacturing process. This degradation damages the performances of motors. This paper presents topology optimization of rotating machines considering the localized magnetic degradation caused by punching process. It is shown that the optimized synchronous reluctance motors obtained by this method satisfy the torque constraint under the existence of the magnetic degradation. [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]

A Preisach-type vector hysteresis model is developed to represent anisotropic material characteristics under static and dynamic conditions. Bi- and uniaxial anisotropy are incorporated by generalizing the input projection of the vector model. Frequency-dependent eddy current and excess effects are considered by an additional field strength component. The model is applied to simulate the magnetic properties of weakly anisotropic nonoriented magnetic steel. The simulation results are successfully validated against measurements under alternating and circular flux carried out on a rotational single-sheet tester. [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]

This paper deals with the analysis of a 1-D magneto-dynamic model (MDM) of soft magnetic steel sheets (SMSSs) under arbitrary excitation conditions. In the presented analysis, the MDM is coupled with the static hysteresis model proposed by Tellinen. The coupled model of SMSSs is evaluated using measured excitation voltages as well as measured excitation currents directly as the model input variables, where both excitation cases are compared and evaluated versus measurements. The calculated results show a good agreement with the measurements. Based on the presented analysis properties, advantages, and flexibility of the MDM model as well as the limitations of the presented coupled model are pointed out, where guidelines for an improved coupling are also given. [ABSTRACT FROM AUTHOR]

Transformer steel, fully processed Hi-B (high permeability) grade of cold rolled grain oriented (CRGO), was subjected to relatively minor, 0 to −55 MPa, stresses. Detailed magnetic and microstructural characterizations were then carried out. Shift of hysteresis loop and clear degradation in magnetic properties, namely increase in core loss and drop in permeability, were noted. Though absence of mesoscopic plastic strains was confirmed, possibilities of minor local plastic deformation cannot be ruled out. Prior deformations: 1) modified residual strain/stress signatures in both CRGO laminates and Forsterite (Mg2SiO4) coating and 2) caused corresponding degradation in magnetic performance. Redistribution of residual stresses through local plastic deformation appears to be the plausible justification for these observations. This paper brought out clear correlations between degradation in magnetic properties with introduced residual stress/strain. [ABSTRACT FROM AUTHOR]

Transformer cores are assembled from several packages of different widths. Furthermore, circular limbs tend to be combined with semicircular yokes. These characteristics mean that the core represents a complex 3-D system. A consequence is balancing off-plane flux (z-flux) perpendicular to the core plane. Measurements of z-induction on model cores show that mere inhomogeneity of stacking may yield significant values of flux density \({\boldsymbol{B}}_{{\mathbf {z}}}\) in the normal direction. Close to overlapping regions of corners and T-joints, the order of 10 mT was observed. Losses prove to increase in a nonlinear way with increasing \({\boldsymbol {B}}_{{\mathbf {z}}}\) for both alternating magnetization (AM) and rotational magnetization (RM). Effects become significant for \({\boldsymbol {B}}_{{\mathbf {z}}} \,{\boldsymbol {=}}~10\) mT, with losses showing increases of order of 30%. The corresponding increases of magnetostriction are much more pronounced, reaching 100%. These increases are clearly supported by the results of Kerr effect studies of domains. They reveal distinct increases of oblique domains. For 1-D AM, they are restricted to inner lancet slopes. For 2-D RM, the latter merge to inner plate domains. For the 3-D case of additional z-flux, the formation of plates is significantly enhanced. Plates can be assumed as a main source of both rising hysteresis losses and increasing magnetostriction. [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]

This paper deals with a new analytical parametric magneto-dynamic model of a thin soft magnetic steel sheet (SMSS). The interdependence of the magnetic field and eddy currents inside such an SMSS is calculated by dividing the sheets into an arbitrary number of slices. Using an adequate number of slices, the magnetic field and eddy currents are described piece-wise uniformly across the SMSS for a given excitation dynamics. Dynamic hysteresis loops for arbitrary excitations can be calculated using the proposed model. The calculated results are validated by the measurements on a non-oriented SMSS. [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]

The influence that manufacturing processes have on electrical steel properties is investigated. The investigation is carried out by considering changes in measured electromagnetic quantities and the changes to parameters of a physics-based hysteresis model. The parameters of an inverse Jiles–Atherton hysteresis model are identified using nonlinear least square method and compared with measured data from steel samples that have undergone different stages of manufacturing. The results of the study may be used as a first step to the inclusion of manufacturing effects in models of electromagnetic devices. [ABSTRACT FROM PUBLISHER]

This paper proposes a modeling method of two-dimensional (2D) magnetic properties based on magnetic energy obtained from several one-dimensional (1D) magnetic properties with different inclination angles from rolling direction. We compare the measurement results of non-oriented electrical steel sheets by 2D and 1D single sheet testers (SSTs) and confirm that almost the same magnetic properties can be obtained from each tester. Based on several 1D magnetic properties measured by the 1D-SST, we evaluate a magnetic energy by using a Fourier series expansion. By differentiating the estimated magnetic energy, we can obtain the perpendicular components of magnetic field with respect to the magnetic flux density which cannot be measured by the 1D-SST. In order to confirm the validity of the proposed method, we compare the estimated 2D magnetic properties with measured ones. Finally, the calculation procedure of the Jacobian matrix is presented and the proposed method is applied to the finite element analysis. [ABSTRACT FROM PUBLISHER]

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]

Magnetic and magnetostrictive behaviors of magnetic materials are very sensitive to mechanical stress and especially to plastic deformation. A model based on the decomposition of a plastified material into mechanically hard and soft phases has been proposed. An appropriate experimental procedure is presented in order to validate the model. The magnetic and magnetostrictive behaviors of a dual-phase steel are carried out. Measurements are made at unloaded stress and under various applied stress to observe a recovery phenomenon predicted by the modeling. Experiments and modeling are compared. [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]

CYCIAE-100, a 100 MeV H-cyclotron under construction at China Institute of Atomic Energy, is a compact H-cyclotron. Since its upper/bottom and return yokes are each made of a casting steel of large dimension (with final dimension of 6160 mm in diameter and weight of 140 tons each piece), special attention has to be paid to the annealing procedure to insure the magnetic properties of this kind of large scale casting steel pieces with high purity. First, this paper presents an overview of annealing strategies to improve the magnetic properties of large scale casting steel. Then an estimation of heating time during annealing procedure has been made by FEM simulation based on the current status of annealing facility in China and has been indirectly verified by a rule of thumb from the results in TRIUMF design note. Based on that as well as on a close collaboration with CITIC HMC, the manufacturer of large casting steel mill, an agreement on detailed annealing procedure has been reached and issued for production of large casting steel for CYCIAE-100. The results from the practice have been obtained and the detail procedure will be presented in this paper as well. [ABSTRACT FROM AUTHOR]

IEC TC 68 is the standards committee which prepares international standards relating to magnetic alloys and steels. The committee works within the framework of the IEC and specializes in producing documents which standardize the specifications that apply to these materials and the measurement procedures for the relevant magnetic and physical properties. [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]

In this paper, stress and fatigue-loaded ferromagnetic steel samples were evaluated using three different remanent flux leakage transducers. Giant magnetoresistive sensors were used as the pickup elements. Each transducer has its own integrated local magnetizing section, which allows us to magnetize the tested material in different directions. The defect detection dependency on angle, at which it occurs to the magnetizing field and sensing element, is minimized by gathering and then integrating the information from transducers. The performance of the transducers was verified using a steel plate (S355J2G3) with electro-discharge machined notches. Further experiments were carried out using fatigue and stress-loaded steel samples. [ABSTRACT FROM AUTHOR]

Focuses on a study which examined the modeling of thin steel shells placed in a static magnetic field. Behavior of the sheet; Information on global formulations; Conclusion.

Presents information on a study which focused on a two-dimensional hysteresis model constructed to represent the magnetic behavior of steel laminates. Methodology; Identification of model parameters; Conclusions.

Presents information on a study which developed a mathematical model for magnetization changes in a steel rod under varying torsion in a constant applied magnetic field. Extension to the law of approach to torsional stress; Changes in the energy balance equation; Details on energy balance formulation for torsional stress.

Provides information on a study which measured tensor magnetic hysteresis loops for a pipeline steel cube. Stages of the magnetizing process; Methodology; Results and discussion.

Presents information on a study which improved the single sheet testers used for measuring two-dimensional (2-D) magnetic properties of silicon steel at high flux densities. Significance of measuring 2-D magnetic properties; Parameters to be evaluated in 2-D magnetization property; Results and conclusion.

Presents a study which examined the effects of neutron and proton dose on the magnetic properties of a reactor pressure vessel (RPV) steel. Overview of the evaluation of the radiation damage of nuclear RPV steel through hysteresis loop and Barkhausen noise; Experiments; Results and discussion; Conclusions.

Presents information on a study on the effect of skin-pass rolling direction on the magnetic properties and directionality of semiprocessed non-oriented electrical steel sheets produced by skin-pass rolling process. Uses of the magnetic directionality of steel sheets; Methodology; Results and conclusion.

Measures the conventional magnetic parameters and Barkhausen noise in pressure vessel steel samples. Three stages in neutron dose variations; Deterioration of mechanical properties brought by neutron irradiation.

Determines the effects of magnetic properties dependence on crack size in the distribution of magnetic flux in steel components. Relationship between measured remanence and the crack area; Materials and experimental procedures; Calculations on the leakage field.

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]