Non-oriented Steel Research Articles

Magnetostrictive strain monitoring in Non-Oriented Si-Fe steels using a SAW resonator sensor

The aim of this study is to introduce a new technique for characterizing the magnetostrictive behavior of non-oriented ferromagnetic steel sheets using miniaturized wireless surface acoustic wave sensors (SAW). Unlike conventional optical and electromechanical techniques, this type of sensor offers advantages such as on-board capability, high-temperature resistance (up to 400 °C), and the ability to be connected remotely. The final objective is to monitor magnetic stresses in electrical machines, aligning with the requirements of Industry 4.0 and predictive maintenance. The focus of the present study is the measurement of magnetostriction in ferromagnetic steel sheets, employing a wireless surface acoustic wave resonator operating within the 433 MHz ISM band, under various mechanical fixation configurations. To ensure the accuracy and reliability of SAW measurements, a commercial strain gauge is employed as a reference sensor. Measurements are conducted at different excitation frequencies to explore the phenomenon comprehensively.

Study on Nucleation and Growth of Columnar Grains in Non-Oriented Steel by Phase Transformation

Study on Nucleation and Growth of Columnar Grains in Non-Oriented Steel by Phase Transformation

Effect of Preheating on the Mechanical Workability Improvement of High-Strength Electrical Steels during Tandem Cold Rolling

Cold-rolled silicon steel strip products are widely used as the main soft magnetic components in cores of electrical motors, generators, and transformers. In the case of rotating electrical machines, the so-called non-oriented electro-technical steels are normally applied. They are characterized by a similar behaviour to the induced magnetic field found in all sheet plane directions. The kind of soft magnetic alloys that defined herein not only possess an isotropy of electromagnetic properties, but also high mechanical strength; such alloys are called high-strength electro-technical (HSET) steels. These commercially produced HSET steels contain a high silicon content in the range of 3–4 wt.%. However, if the silicon content exceeds 3%, the machinability of Fe–Si alloys is dramatically reduced and they become much more brittle as a consequence. According to this, regular hot band brittle damage occurs during cold deformation at a high-speed tandem rolling mill. In accordance with these reasons, the production of thin high-strength silicon steel grades using the traditional methods of cold rolling deformation is extremely problematic and it is characterised by a high degree of steel sheet mechanical damage. In this scientific work, the effect of preheating hot-rolled strips on their mechanical workability improvement during tandem cold rolling was investigated. The results of this study indicate that the cold rolling of hot bands at elevated temperatures increases their resistance to brittle failure and mechanical plasticity. Moreover, the mathematical simulation clearly demonstrates that residual stress is distributed relatively homogeneously across the thickness of samples, which were cold rolled at 100 °C in contrast to the same ones deformed at room temperature.

Crown Prediction of Hot‐Rolled Silicon Steel Using Transfer Learning Network Fused with Whale Optimization Algorithm

Massive amounts of data are generated during hot strip production in the hot‐rolling metal forming process; the resultant dataset is sufficient for model learning in strip steel crown prediction. However, the data of high‐grade nonoriented silicon steel are limited, and the rolling process parameters differ, resulting in poor crown prediction. Herein, a model based on the whale optimization algorithm and transfer learning to predict the crowns of hot‐rolled high‐grade nonoriented silicon strip steel is presented. The model is composed of convolutional and linear layers. The whale optimization algorithm is used to optimize the hyperparameters and obtain an optimal model during pretraining. The model is then fine tuned based on insufficient silicon steel data to achieve model migration. The application results show that the correlation coefficient reaches 0.993, which is the highest prediction accuracy among the comparison models. Furthermore, the root mean square error is 1.14 μm, and the hit rate within 4.0 μm of the crown deviation reaches 99.502%. In addition, the influences of four parameters on the crown of the silicon steel strip are studied based on the response surfaces. The results indicate that the proposed model can efficiently predict silicon steel strip crowns.

Physically consistent testing of large-frequency-band magnetic losses of non-oriented electric steel considering dynamic anisotropy

Non-oriented (NO) magnetic steels show gradually increasing relevance over an extended range of frequencies, in particular for electric drives. However, until now, data for corresponding characteristics like losses P are available in very restricted ways. A reason is that loss testers are standardized for technical low frequency (LF) until now. Here we report detailed loss data for three steel types, tested by broad-band single sheet testers that offer tests up to high frequency (HF), for values of f = 10 kHz, for steel samples of 500 × 170 mm2 (or 500 mm). In solving a specific problem of NO steel, very high values of H of magnetic field strength are considered by “True Field Air Flux Compensation.” For rising f, the three steels show strong, non-linear increases in losses P, up to about 100 W/kg. With respect to anisotropy, corresponding factors were defined for rolling direction and transverse direction (TD). The effective “field anisotropy” AH tends to show high values for LF but sinks dramatically for HF due to strong eddy currents. The analogously defined “loss anisotropy” AP is lower a priori. In addition, decreases in HF are less pronounced. The International Electrotechnical Commission-standardized “loss anisotropy factor” is generally lower by more than a factor of two, with values up to 30% for LF that may sink to zero for HF due to eddy current mechanisms that are rather independent from crystalline texture. In conclusion, for high dynamics, the effective anisotropy deviates completely from LF-based texture characteristics. Additional analyses of power functions prove that during a period of magnetization, strong anisotropy exists with respect to alignments of atomic moments, in particular for the TD.

The Effect of Grain Size and Silicon Content on Non-Oriented Grain Steel Anomalous Loss Through Frequency Excitation in The Medical Healthcare by Using Big Data Analysis

Using steels for commercial electromagnetic purposes produced by the Jordan Steel Group, the current research will look into the effects of grain size and excitation frequency on anomalous losses and the characteristics of the hysteresis curve of the anomalous loss. The final heat treatment of 21 steel samples for commercial electromagnetic purposes, divided into three groups differing in chemical composition, was carried out in the laboratory to determine the influence of electrical resistivity, grain size, and excitation frequency on total, hysteretic, and seek a better understanding of the effect of these variables on the anomalous loss portion. Compare the experimental data to the hypothesized constitutive equations in the literature and study to create the parasitic loss plus hysteretic loss curve using interpolation, superimpose it on the total loss hysteresis curve, then correlate the areas between the curves with anomalous loss and energy dissipation processes. It is possible to determine from micrographs and grain sizes that there was an increase in grain size due to normal brain development and a minor fraction of aberrant growth at high temperatures.

Magnetic properties deterioration of non-oriented steel due to laser cutting

In the manufacturing process of electrical machines, laser cutting is widely used to produce the laminations of cores. The internal stresses introduced by the high-energy laser beam will lead to deterioration in the magnetic properties of the non-oriented silicon steels. To accurately predict the core losses of the electrical machines, it is important to analyze the deterioration degree and the deterioration mechanism of the non-oriented steel sheets caused by laser cutting. In this paper, first, the local magnetic properties of the non-oriented steel 35WW250 at different positions are measured under the alternating sinusoidal excitation, in which the degradation degree is evaluated based on the core loss from the macroscopic perspective. Second, from the microscopic perspective, the observed magnetic domain patterns at the edge and those evolutions under the excitation of the magnetic field are investigated. The experimental results demonstrate that laser cutting can lead to the magnetic degradation of the non-oriented steels with a transverse depth of 18 mm from the edge. Moreover, the laser cutting process leads to significant variations in the patterns of the magnetic domains at different positions. The magneto-optical observation and local magnetic measurement verified the effectiveness of the analytical method, which is of great significance for the evaluation and improvement of the processing technique of the silicon steels.

Linear switched reluctance motor for traction propulsion system using configuration of electric locomotive

The linear switched reluctance motor (LSRM) has emerged to be the most promising alternative due to the development of power controllers in the past years. In this paper, a novel configuration of LSRM with an active-stator-passive-translator is proposed for the traction propulsion system. It comprises a short active stator retrofitted with the transit mover, while a long stationary translator is considered as rail guidance of the system. In this paper, high grade M-19 cold-rolled non-oriented steel is utilized for manufacturing the stator and translator cores. The proposed configuration of electric locomotive makes use of force generated from linear switched reluctance motors to propel it on parallel rails and pushes the coaches attached to the wagon for carrying the functional load. Finally, the motor characterization is performed in ANSYS electromagnetic simulation tool, to determine the applied forces, coupling inductance, and strength of magnetic field of the proposed LSRM for the traction propulsion system. Thus, the experimental evaluation is carried out for various parameters to depict the sustainability and suitability of the LSRM for high-speed transition system.

Practical Aspects of Instantaneous Magnetization Power Functions of Silicon Iron Laminations

Magnetic energy loss P of SiFe steel represents a key factor for the efficiency of soft magnetic machine cores. Traditionally, they are operated with 50 Hz (or 60 Hz), a frequency value that yields rather balanced portions of hysteresis loss and eddy current loss. In equivalent circuits of transformers, P tends to be represented by a magnetic power resistance RM, as a constant. For the most important case of sinusoidal induction B of 50 Hz, this would correspond to an instantaneous magnetization power function p(t) that is sinusoidal as well, however, with 100 Hz (or 120 Hz). On the other hand, from complex, non-linear mechanisms of hysteresis, it is obvious that p(t) should be strongly non-sinusoidal, even for exactly sinusoidal B(t). So far, almost all corresponding instantaneous investigations were restricted to calculated modelling of loss portions and transient modelling. On the other hand, for the first time, the present study was focussed on functions p(t) as measured at IEC-standardized samples of industrially relevant steel. Practical evaluations are discussed with respect to the revealed “history” of magnetization processes, as well as for product characterization. For these tasks, a novel digitized “Low-mass Single Sheet Tester” was developed that was applied for both non-oriented steel (NO) and grain-oriented steel (GO), for 50 Hz. Interpretations proved to be favoured by relating p(t) to total P, according to an instantaneous power ratio. As a result, both steel types revealed strongly non-sinusoidal power functions, with short durations of negative p. Negative p proved to be most pronounced for NO steel, as a measure for the onset of reversible turns of atomic moments. As a consequence, p(t) comprises strong upper harmonics of 200 Hz and even 300 Hz. Based on theoretical considerations, we split p(t) in a dissipative loss power function pL(t) and in a potential energy power function pP(t). Finally, we used p(t) to determine the corresponding power resistance RM(t) that proves to be a distinctly nonlinear function as well. It resembles a rectified co-sinus, also exhibiting short negative spikes that reflect the crystallographic dis-orientation of the polycrystalline material.

State of the art of additively manufactured electromagnetic materials for topology optimized electrical machines

Metal additive manufacturing (AM) technology is maturing. Although currently slower and less reliable than traditional production methods, AM systems shine when producing parts with unconventional topologies or in small quantities. Like countless other research communities, the electrical machine (EM) research community has shifted considerable efforts towards integrating AM systems into the EM production cycle to implement more powerful and efficient topology optimized (TO) next-generation EMs. In this paper, the state-of-the-art printing of soft magnetic, hard magnetic, and electrically conductive materials was investigated to evaluate the maturity of each material type for integration into EM construction. The highest maturity was identified for AM pure copper, showing characteristics equivalent to commercial high purity copper. In contrast, AM permanent magnets were the least mature: suffering from low power density and limited magnetization capacities. Printed soft magnetic steels were characterized as halfway in-between: on one side showing equivalent DC magnetic properties to conventional non-oriented steels, but on the other – suffering from high eddy current losses in AC applications. Based on the study's findings, it would appear that the emergence of additively manufactured EMs is only a matter of time. We predict a dramatic increase in the printing of prototype TO components within the next few years, focusing most likely on TO machine windings, heat exchangers, and synchronous rotors.

Time‐averaged and instantaneous magnetic loss characteristics of different products of electrical steel for frequencies of 16 2/3 Hz up to 500 Hz

Traditionally, products of electrical SiFe steel are focussed on applications for frequencies of 50–Hz. However, the recent developments of electric drive systems yielded a strong extension of the range from f = 16 2/3 Hz up to ca. 500 Hz. In spite of high industrial relevance, the literature offers the corresponding data on the material’s magnetic energy losses in very rare ways. This paper reports a first comparative, multi-parametric study on eight different steel products that comprise non-oriented steels (NO), grain-oriented steels (GO) and scribed grain-oriented steels (SGO). Consistently at IEC-standardized samples, they were analysed for the whole frequency range that was split into low frequency (LF) and medium frequency (MF), with 80 Hz as the border. Data is presented on time-averaged total losses P, on the corresponding hysteresis losses PH and eddy current losses PE. LF proved to be governed by PH and MF rather by PE, however, with strong variations. Further, instantaneous magnetization power functions p(φ) were determined for basic insights into the involved temporal developments of energy dissipation. GO-steels yielded profiles close to rectified co-sinus functions that can be fully attributed to dissipative losses. On the other hand, p(t) of NO-steels and SGO-steels prove to include negative segments that reflect potential energy power, in the course of alignments of atomic moments in instants of high induction. Examples of industrial relevance of the accumulated data are steel production technology, product categorization, failure tracing and energy conversion.

Analysis of the Reasons for the Tearing of Strips of High-Strength Electrical Steels in Tandem Cold Rolling.

High-strength non-oriented electro-technical steels with a low thickness possess excellent isotropy of electromagnetic and mechanical properties which is highly required in the production of high-efficiency electric motors. The manufacturing process of this type of steel includes very important and technologically complex routes such as hot rolling, cold rolling, temper rolling, or final heat treatment. The final thickness is responsible for the decrease in eddy-current losses and is effectively achieved during cold rolling by the tandem rolling mill. Industrial production of thin sheets of high-strength silicon steels in high-speed tandem rolling mills is a rather demanding technological operation due to the increased material brittleness that is mainly caused by the intensive solid solution and deformation strengthening processes, making the dislocation motion more complex. The main objective of this work was to investigate the distribution of local mechanical strains through the thickness of high silicon steel hot bands, generated during the cold rolling. The experimental samples were analysed by means of electron back-scattered diffraction and scanning electron microscopy. From the performed analyses, the correlation between the material workability and the nucleation of cracks causing the observed steel strip failure during the tandem cold rolling was characterized. Specifically, the microstructural, textural, misorientation, and fractographic analyses clearly show that the investigated hot band was characterized by a bimodal distribution of ferrite grains and the formation of intergranular cracks took place only between the grains with recrystallized and deformed structures.

Analysis of Modular Stator PMSM Manufactured Using Oriented Steel

Oriented steel has higher permeability and lower losses in the direction of orientation (the rolling direction) than non-oriented steel. However, in the transverse direction, oriented steel typically has lower permeability and higher losses. The strategic use of oriented steel in a modular Permanent Magnet Synchronous Machine (PMSM) stator can improve machine performance, particularly when compared to a machine designed with non-oriented steel, by increasing both torque and efficiency. Typically, steel manufacturers provide magnetic properties only in the rolling and transverse directions. Furthermore, in modern Finite Element Analysis (FEA) software, the magnetic properties between the rolling and transverse directions are interpolated using an intrinsic mathematical model. However, this interpolation method has proven to be inaccurate; to resolve this issue, an improved model was proposed in the literature. This model requires the magnetic properties of the oriented steel in between the rolling and transverse directions. Therefore, a procedure for extracting the magnetic properties of oriented steel is required. The objective of this work is to propose a method of determining the magnetic properties of oriented steel beyond just the oriented and transverse directions. In this method, flux-injecting probes, also known as sensors, are used to inject and control the flux density in an oriented steel segmented stator in order to extract the properties of the oriented steel. These extracted properties are then used to model an oriented steel modular stator PMSM. The machine’s average torque and core losses are compared with conventional, non-modular, non-oriented steel stator PMSM, and modular, non-oriented steel stator PMSM. It is shown that both the average torque and the core loss of the oriented steel modular stator PMSM have better performance at the selected number of segments than either of the two non-oriented steel stators.

Variations of Magnetic Domain Structures and Microstructures in Non-oriented Electromagnetic Steel Sheets during Tensile Deformation

Variations of Magnetic Domain Structures and Microstructures in Non-oriented Electromagnetic Steel Sheets during Tensile Deformation

ЕКРАНУВАННЯ МАГНІТНОГО ПОЛЯ ПІДЗЕМНОЇ КАБЕЛЬНОЇ ЛІНІЇ ЗА ДОПОМОГОЮ Н-ПОДІБНОГО ЕКРАНА

In the article the magnetic field distributions, generated by underground extra-high voltage (330 kV) three-phase power cable line in the environment, in particular near the cables in the trench and on the ground, are analyzed for using of H-shaped shield made of different materials including aluminum, low carbon steel and non-oriented grain steel. As shown, the best shielding effectiveness is realized by aluminium shield. The H-shaped shield made of high-conducting non-magnetic materials is proposed to use in order to mitigate the magnetic field level on the ground down to regulated nonhazardous values. References 14, figures 7.

Modified-SST for Uniaxial Characterization of Electrical Steel Sheets Under Controlled Induced Voltage and Constant Stress

This article details the development of a uniaxial magnetomechanical bench that allows measuring the effect of constant tensile and compressive stress on the magnetic properties of electrical steel sheets. Following international standards for magnetic measurements, this work proposes reasonable modifications of a single-sheet-tester set up to provide a reliable magnetomechanical characterization of the material. The magnetic circuit and the excitation and control techniques employed are described. Specifications concerning magnetic measurements are also offered, alongside mechanical considerations regarding the antibuckling fixture developed to allow the application of compressive stress. Finally, results obtained for various stress levels and frequencies are validated and analyzed. Among other results, the proposed bench allows observing the negative impact of compressive stress on magnetic properties of nonoriented steel, as well as the positive effect of mild tensile stress.

Proposal of Core Structures for Iron Loss and Noise Reduction of Three-Phase Reactor With Anisotropic Iron Core

To reduce the iron loss and noise of a three-phase reactor composed of grain-oriented (GO) steel plates, two types of core structures are proposed in this article. In the first type, the ordinary brick core model is improved to a hybrid one composed of GO and nonoriented steel plates, and in the second type, the T-joint part of the ordinary oblique-joint core model is improved to a straight joint. To show the effectiveness of the improved models, the iron loss and displacement distributions in the four core structures are evaluated using the 2-D magnetic field and mechanical analyses. In these analyses, the magnetic characteristics of the anisotropic cores are considered in detail. Namely, in the magnetic field analysis, the B-H curves in the arbitrary directions are considered. In the iron loss calculation, the rotational iron loss is calculated using the iron loss curves in the arbitrary directions. Moreover, the methods of calculating the displacements due to electromagnetism and magnetostriction considering the anisotropic B-H curves and magnetostriction in the arbitrary directions are proposed. It is shown that the iron losses and displacements of the two proposed core structures can be reduced compared with the ordinary ones. Moreover, the second proposed model is the most attractive one because both the iron loss and displacement are smaller than the other models.

3-D MACC Modeling of Instantaneous Magnetic Flux Distributions in Epstein Tester

Magnetic energy losses of silicon iron (SiFe) sheets are determined by the standardized methods of single sheet tester (SST) or Epstein tester (ET). The ET is much more compact and can be applied in a large range of frequency. However, it suffers from several sources of systematic errors. The most severe one is given by the magnetic cores flux distribution that shows a strong degree of inhomogeneity. This fact is highly evident. However, it never has been investigated in detail so far. Herein, we report results of a 3-D modeling, performed by magnetic anisotropic circuit calculation (MACC), considering non-linearity in connection with anisotropy, for both non-oriented (NO) steel and grain-oriented (GO) steel. The results reveal substantial differences of the corresponding flux distributions. NO steel proves to be characterized by high homogeneity of induction in rolling direction in the middle sections of the four limbs. However, the four corners show strong inhomogeneity in instants of low global induction, while a transition to more balanced flux arises at peak magnetization. On the other hand, this transition is much less pronounced for GO steel. As a conclusion for the evaluation of losses, a distinction is needed for the two different types of material.

Consideration of ferromagnetic anisotropy in electrical machines built of segmented silicon steel sheets

Electrical steel shows a distinct non-linear and anisotropic behaviour even for non-oriented steel. The flux guidance in electrical machines is realised by ferromagnetic steel sheets, and therefore it is necessary to consider the anisotropy in the simulation to have reliable and accurate results. Due to the fact that the reduction of silicon steel waste in the production process of electrical machines is crucial, and to enhance the material utilisation the segmentation is employed in the construction of electrical machines. The segmentation further allows to enhance the magnetic behaviour of the machine by considering the easy magnetisation axis in the design process. Nowadays, consideration of ferromagnetic anisotropy in the simulation of electrical machines is not accurate. To cope with these inaccuracies, in this contribution, a vectorial anisotropy model based on two-dimensional measurements is employed to the simulation of a segmented electrical machine, which is not state of the art in current machine computation. With the presented methodology, it is possible to simulate and design segmented electrical machines in an accurate fashion taking the ferromagnetic anisotropy into account.

Comparison of Preisach and Congruency-Based Static Hysteresis Models Applied to Non-Oriented Steels

Two hysteresis models are investigated for modeling static hysteresis phenomenon in nonoriented magnetic steels. First, the static Preisach model is studied, and two types of experimental data, i.e., first-order reversal curves (FORCs) and concentric hysteresis loops, are employed to identify the weight function. Due to negative values in the obtained experimental weight functions, the resulting Preisach models show nonphysical behavior. To eliminate this nonphysical behavior, an optimization procedure is applied to remove these negative values. The nonphysical behavior is resolved in the modified Preisach model; however, the model still has poor accuracy for asymmetric loops. Alternatively, a new congruency-based static hysteresis model is proposed. In this model, third- or higher-order reversal curves are approximated using measured FORCs and second-order reversal curves (SORCs) by means of a congruency regularity. According to this regularity, any third- or higher-order reversal curve is congruent to SORCs with the same reversal point. A 3-D piecewise interpolation function is employed to interpolate the measured major loop, FORCs, and SORCs. The proposed model results are compared with quasi-static measurements. The comparison reveals that the model is capable of approximating the magnetization curves for the measurements containing complex-shaped $B$ waveforms with a relative energy error of less than 4%.