Grain-oriented Silicon Steel Sheets Research Articles

Simple modeling of the AC hysteretic property of a grain-oriented silicon steel sheet

A homogenized model based on the Pry and Bean model is generalized to represent the ac hysteretic characteristics of an actual grain-oriented silicon steel sheet. A parameter for the frequency dependence of eddy-current loss is introduced. The generalized model improves the evaluation accuracy of eddy-current loss and the representation of ac B--H loops under the condition of a sinusoidal magnetic flux. The generalized model also accurately represents ac B--H loops having minor loops.

Influence of Magnetic Stray Fields Created by Grain Boundaries on Magnetization Processes of Laminated Silicon Steel Sheets

The topology of the magnetic stray fields created by grain boundaries and its influence on magnetization processes of laminated grain-oriented silicon steel sheets were investigated. It was found that the variations in the magnetic flux density in laminated sheets, caused by the magnetic stray fields at the grain boundaries of adjacent layers, can be as large as 0.1–0.12 T at the average level of magnetic induction 1.75 T in the core. The induction distribution along the rolling direction in adjacent layers near the grain boundaries changed according to the spatial distribution of the longitudinal component of the stray field.

Effects of laser irradiation on iron loss reduction for Fe–3%Si grain-oriented silicon steel

The effects of laser irradiation on iron loss reduction for Fe–3%Si grain-oriented silicon steel sheet were investigated. The local tensile residual stress states near the laser irradiated cavity lines were observed by using the new X-ray stress measurement method for a single crystal. Although the higher laser power induced the larger tensile residual stresses, the minimum iron loss was obtained at the medium tensile residual stress conditions of about 100–200 MPa. The increase of Vickers hardness was observed with increasing laser power, which was the mark of the plastic deformations induced by the laser irradiation. The tensile residual stress reduces eddy current loss and the plastic deformation increases hysteresis loss of the material. The total iron loss is determined by the balance of these two effects of laser irradiation.

A study of the loss characteristics of the amorphous magnetic material under the distorted wave magnetic flux

In this paper, iron loss characteristics of amorphous magnetic material under distorted waveforms have been described. The loss characteristics of amorphous magnetic materials have been compared with grain-oriented silicon steel sheet. The measurement of the iron loss has been carried out with SST. In the result, it is found that amorphous magnetic materials have better characteristics under the distorted waveforms than grain-oriented silicon steel sheet.

Improvement of E&S modeling for eddy-current magnetic field analysis

This paper presents improvements of Enokizono and Soda (E&S) modeling of vector magnetic properties in arbitrary direction considering alternating and rotating hysteresis of grain-oriented silicon steel sheets. Reluctivities of this modeling were calculated from measurement data obtained through two-dimensional magnetic measurement. However, the measurement was done by only 50 Hz, and the influence of the frequency was not examined fully. In this paper, we examine the frequency dependence of hysteresis curve and present an improved modeling considering frequency dependence of the eddy current.

Controlled circular magnetization of electrical steel in Rotational Single Sheet Testers

A new waveform control algorithm for Rotational Single Sheet Testers (RSST) is presented. The new algorithm achieves circular magnetization for high induction levels even in samples of grain-oriented silicon steel sheets. The algorithm is based on the circuit model of the system and takes the coupling between the two phases of the RSST into account. Identification of the parameters of the measurement setup with the Least Squares (LS) method avoids preliminary measurements on the sample and the setup. The performance of the algorithm is illustrated by measurements on a grain-oriented sample. The algorithm is universally applicable and allows fully automated measurements.

Calculation of magnetostatic energy fm related to small-angle grainboundaries in three-axis ferromagnetics such as silicon steel

A calculation was performed of the energy volume density fm in amagnetic field H⃗m that is caused by planar small-angle grainboundaries (GBs) in a polycrystalline ferromagnetic, such as silicon steel,with grains magnetized to saturation (M = MS). Equations for the fieldcomponents, Hmξi and energy, fm, were obtained and solved,taking into account the µ*-effect near GBs. It is shown that deviationsof the vectors such as M⃗S from the easy directions,⟨100⟩, under the action of fields H⃗m at GBs leads to anessential (in ten times) decrease of the (Hmξi)max component andthe ⟨(fm)max⟩ values. The influences of the orientation ofthe GB surfaces and µ* on the fm distribution are discussed. Theresults of the computation are compared with the corresponding experimental datafor samples of grain-oriented silicon steel sheets.

Experimental investigation of μ*-effect near the grain boundaries in grain-oriented silicon steel sheets

The regularities of magnetization M distribution and behaviour of domain structure near the planar grain boundaries (GB) in grain-oriented silicon steel (GOSS) sheets, which had been magnetized by homogeneous external magnetic fields along the rolling direction, were investigated. It was found that there are such perturbations δ M of the spontaneous magnetization M s which is the direct experimental evidence of μ*-effect existence at the GB. The peculiarities of this effect near the planar GB with different orientation of axes 〈1 0 0〉 at neighbouring crystals of GOSS sheets are discussed.

Measurement system of alternating magnetic properties under DC-biased field

This paper presents magnetic properties under DC-biased magnetization of a grain-oriented silicon steel sheet 30Z. We have practised the measurement of DC-biased flux density by using flux meter directly. The DC-biased magnetic properties have been made clear in this experimental approach.

方向性電磁鋼板の交流磁気シールド特性

We measured the magnetic shielding effectiveness of a cubic box constructed from grain-oriented silicon steel sheets. We also measured the effect of varying the box wall thickness on the shielding effectiveness. Experimental results were compared with theoretical expected results. We found that the shielding effectiveness for an alternating magnetic field in the 30 Hz to 5 kHz range was qualitatively explained by the permeability of materials and eddy currents in materials, and susceptible to the gap at the joint of the shielding materials.

単板磁気試験器を用いた偏磁気特性の測定

A common method for the measurement of dc-biased magnetic properties is the use of ring specimens. Although ring specimens are popular for measuring magnetic properties, it takes a long time to prepare the windings. It is therefore difficult to compare various kinds of specimens in a short period. This problem can be solved by using a single-sheet tester (SST). This paper presents an improved measurement system for dc-biased magnetic properties and some measured results for grain-oriented silicon steel sheets of different rolling direction.

Magnetization properties and domain structures of grain-oriented silicon steel sheets due to bending stress

The magnetization properties of grain-oriented silicon steel sheets under bending stress are not a simple combination of the properties due to tensile stress on the convex side and compressive stress on the concave side. Domain structures on both sides are different from the structure of independent stress of tension or compression alone. Magnetostrictions on both sides are measured and the interaction between magnetization properties on both sides is explained partly.

Investigations of magnetostatic fields related to grain boundaries in silicon steel sheets

The origin and peculiarities of the spatial distribution of the magnetostatic fields m near the planar grain boundaries (GB) oriented perpendicular to the rolling direction (RD) in grain-oriented silicon steel (GOSS) sheets, which are magnetized along the RD to induction above 1.0 T, are investigated. It was found experimentally that there are perturbations of the net magnetization in grains near the planar GB even at inductions close to saturation Bs. Such perturbations exclude ruptures of the net magnetization normal component Mn and the appearance of magnetic charges (m = µ0 Mn = 0) on the GB surfaces. The calculation of the field m components related to the planar GB was carried out with our assumptions that net magnetization inhomogeneities (the volume magnetic charges m = -µ0 div ) in grains are the sources of this field. The results of the computation are in good agreement with the results of the field m component measurements for the samples of GOSS. Some regularities of magnetic interaction between neighbouring grains in GOSS sheets are discussed.

Effects of scratching on two-dimensional magnetic properties in grain-oriented silicon steel sheet

Two-dimensional magnetic properties on silicon steels with inclined scratch have been studied using the alternate flux in one direction, thus in an arbitrary direction, and the rotational flux condition. Scratching effect on iron loss under rotational loss differed considerably by direction of scratch, and varied by sample.

Single sheet tester having open magnetic path for measurement of magnetostriction of electrical steel sheet

A single sheet tester having closed magnetic path (a closed type of SST) has a problem that measurement accuracy of magnetostriction is considerably affected by electromagnetic force between specimen and yoke. Therefore, an open type has been developed. In order to get uniform flux distribution in a sufficiently large region, a compensating magnetizing winding is installed, and a method of waveform control is investigated, in which applied voltages to main and compensating windings are adjusted individually. The effectiveness of the newly developed open type is demonstrated by measuring magnetostrictions of thin amorphous sheet as well as highly grain-oriented silicon steel sheet.

A New Method of Grain Imaging for Highly Grain-Oriented Silicon Steels.

A new method is presented by which grains in grain-oriented silicon steel can be imaged clearly through an overcoating. A miniaturized magnetic anisotropy probe consisting of an exciting coil and a pickup coil is used as a scanning device. Each grain of the silicon steel is detected as a region within which the easy axis of the magnetic anisotropy is determined to lie in a common direction. Because of its built-in spatial differentiation, the probe is also sensitive to magnetic dis-continuities in a specimen. With these two probe attributes, grains are imaged with the grain boundaries enhanced. The alignment of the easy axis, that is, the [100] direction projected onto the scanning plane with respect to the rolling direction, is displayed on a gray-scale level. Imaging results are shown for highly grain-oriented silicon steel sheets.

方向性けい素鋼板の交流磁気シールド特性

The shielding effectiveness of an alternating magnetic field was studied experimentally and analytically by comparing shields made of grain-oriented silicon steel sheets with shields made of non-oriented silicon steel. Magnetic shielding in alternating fields became complex owing to anisotropic-frequency-dependent permeability and eddy currents. Shields with axes cross-stacked showed higher shielding effectiveness and isotropic distribution. The analytical results obtained by 3-D FEM showed some discrepancies with the experimental results.

Local iron loss distribution in a grain-oriented 3% silicon steel sheet. Two dimensional magnetic measurement

This paper presents the distributions of local magnetic properties in a grain-oriented silicon steel sheet (23ZH) without insulator coating, measured by using the two-dimensional magnetic sensor. It is well known that the local distributions of the flux density B and the field strength H in a grain-oriented silicon steel sheet are not uniform due to orientation. The properties, namely, the H-vector, the B-vector, the hysteresis loop and the iron losses are depending on the local orientation in a grain. The result shows the relationship between the magnetic properties and the grain structure in the specimen.

Local distribution on magnetic properties in grain-oriented silicon steel sheet

Grain-oriented silicon steel is the most important soft magnetic material used as core material of large transformers, large rotating machines, and pole transformers. Total loss of grain-oriented silicon steel tends to become lower with an increasing degree of texture. However, the material which has a higher degree of texture ordinarily contains larger grains, and the materials which have larger grains show higher total loss due to increased eddy current loss. As the gauge is reduced, the rate of decrease in total loss becomes lower for the thinner gauge due to increased hysteresis loss. However, the investigation of local magnetic properties due to grain situation in this sheet was not discussed from the viewpoint of the distribution of localized magnetic properties, for example, iron loss, hysteresis loop, behavior H vector (magnetic field strength) and B vector (Magnetic flux density). This paper describes the distribution of magnetic properties in high oriented silicon steel sheet, which are loss, hysteresis loop, and locus of field strength.

Effect of rolling condition on textures and magnetic properties in thin grain-oriented silicon steel sheets

We investigated the effect of rolling conditions on the textures and magnetic properties in order to advance the reduction of iron loss in thin grain-oriented silicon steel sheets which can be produced by using the three-stage rolling method. In this contribution, it was clarified that the sheets are completely covered with highly oriented (110) grains when the amount of the rolling reductions become more than 50 % in all the rolling processes. Consequently, thin silicon steel sheets with the highest value of B 8 (the magnetic induction at 800 A/m) can be produced under the same optimum condition.