Electrical Steel Research Articles

Study on Microstructure and Texture of Fe-3%Si Ultra-Thin Ribbons Prepared by Planar Flow Casting.

In this paper, Fe-3%Si ultra-thin ribbons prepared by the planar flow casting (PFC) technique were subjected to temper rolling and annealing treatments. The microstructure and texture evolution during this process were examined through experimental measurements coupled with crystal plasticity finite element (CPFE) simulation to assess the feasibility of preparing ultra-thin non-oriented silicon steel using PFC ribbons. The results indicate that the PFC ribbons exhibit a significant columnar crystal structure, and {001}-oriented grains comprise over 30%. After being annealed, the grains with different orientations grew uniformly, the texture components were basically unchanged, and the {001} texture was well preserved. When annealing was carried out after temper rolling with a reduction rate of 7%, uneven grain growth was observed, and the growth tendency of the {001} grains, especially, surpassed that of the {111} grains, with an elevated temperature which peaked at 950 °C, where the proportion of {001} grains was maximal. When being annealed after temper rolling to 15%, grains of other orientations showed significant growth at each temperature, while the {001} grains did not show an obvious growth advantage. Utilizing the CPFE, the deformation-stored energy distribution of each characteristic-oriented grain was simulated, and it was shown that compared to the 15% rolling reduction rate, the deformation-stored energy accumulation of {001}-oriented grains after being rolled to 7% reduction was significantly lower than that of {111}-oriented grains. It suggests that the larger stored energy difference makes {001} grains show a stronger growth advantage based on the SIBM mechanism during annealing, after being rolled with a reduction rate of 7%. Overall, for the synergistic optimization of microstructure and texture, rolling with a 7% reduction rate followed by annealing at 950 °C in a hydrogen atmosphere is most advantageous.

Simulation of the Effects of Weld-Packaging on the Electromagnetic Properties of Electrical Steel Sheets Using a Local Varying Material Model

Simulation of the Effects of Weld-Packaging on the Electromagnetic Properties of Electrical Steel Sheets Using a Local Varying Material Model

Errata to “Analysis of Magnetomechanical Properties at the Tooth-Yoke Embedding Position in Grain-Oriented Electrical Steel Electric Motors”

Errata to “Analysis of Magnetomechanical Properties at the Tooth-Yoke Embedding Position in Grain-Oriented Electrical Steel Electric Motors”

Comprehensive magnetic properties of grain-oriented silicon steel sheet considering anisotropy under mechanical stress

The cores of transformers and reactors are subjected to mechanical stresses during both manufacturing and operation, these stresses exert an influence on the magnetic properties of the cores. Additionally, there exists rotating magnetic flux within the cores during operation. Therefore, it is necessary to further consider the magnetic properties of grain-oriented silicon steel sheet in the direction perpendicular to the rolling direction. To delve deeply into the comprehensive magnetic properties of grain-oriented silicon steel sheet under mechanical stress, with a particular focus on both the rolling direction and the direction perpendicular to it, this paper presents the establishment of a comprehensive magnetic properties measurement platform for grain-oriented silicon steel sheet that possesses stress adjustment capabilities. Through meticulous measurements, the impacts of tensile and compressive stresses on the magnetic hysteresis loops, B-H curves, relative permeability, magnetostriction, and iron loss characteristics of grain-oriented silicon steel sheet in both the rolling direction and the perpendicular direction were obtained and analyzed. The measurement results and subsequent analysis indicate that tensile and compressive stresses exert an influence on the magnetization characteristics of grain-oriented silicon steel sheet. Moreover, the extent of this influence varies between the rolling direction and the direction perpendicular to rolling for both tensile and compressive stresses; In the rolling direction, compressive stress promotes the magnetostriction of the grain-oriented silicon steels, while tensile stress inhibits it. In the direction perpendicular to rolling, both tensile and compressive stresses inhibit the magnetostriction of the grain-oriented silicon steels, with tensile stress exerting a greater inhibitory effect; Tensile stress acts to reduce the iron loss of grain-oriented silicon steels, whereas compressive stress increases it, this pattern is consistently observed in both the rolling direction and the direction perpendicular to rolling.

Development of Partial Non-Magnetization Improvement for Silicon Steel and Rotor Evaluation

Development of Partial Non-Magnetization Improvement for Silicon Steel and Rotor Evaluation

New method for determining iron power losses in switched reluctance motors with laminated and composite magnetic cores

Power losses from motors and drives can decrease their efficiency. The development of devices with high efficiency is a necessity nowadays, with a view to reducing CO2 emissions. The application of new magnetic materials is one method for increasing the efficiency of motors, although prediction and calculation of the losses in the magnetic circuits of motors are also very important. To reduce the iron losses, iron powder composites are used here instead of Fe-Si laminated steel sheets, in a low-power switched reluctance motor (SRM), and a new method of determining the iron loss in the magnetic circuit is developed. Through the use of new materials in the motor, we can achieve a 19% decrease in the iron loss in comparison to a commercial motor. A comparison of the measurement results for our new method of iron loss prediction showed that the difference is approximately 20-26%, depending on the type of magnetic circuit used for the motor. The usage of soft magnetic composites rather than electrical steel sheets can decrease the loss in magnetic circuits. The results from our new method of determination of iron loss are in good agreement with results of measurements, meaning that it can be applied in a detailed analysis of SRMs. The application of soft magnetic composites in electromagnetic and electromechanical converters is a new method for lowering iron losses in new devices. The determination of such losses in SRMs is still challenging, and the proposed method broadens the state of the art in this area. The method developed here is based on motor current measurements, FEM calculations, and measurements of the magnetisation curves and iron loss for samples according to IEC standards. The results obtained in this work can be used by designers for the development of new kinds of SRMs.

Design of Wound-Field Rotor Synchronous Motor for Electric Vehicles using Grain-oriented Electrical Steel Sheet to Mitigate Back-Electromotive Force

Design of Wound-Field Rotor Synchronous Motor for Electric Vehicles using Grain-oriented Electrical Steel Sheet to Mitigate Back-Electromotive Force

Evolution of Crystallographic Texture and Its Impact on Magnetic Losses of Non‐oriented Electrical Steel

In this study, how crystallographic texture and changes in microstructure affect the magnetic properties of a semi‐processed non‐oriented (NO) electrical steel, which is investigated in its as‐received state and after heat treatment, is evaluated. Electron backscattered diffraction analysis shows the variation in texture with a crystallographic orientation changing from a predominance of γ and α fibers to a random one after heat treatment, with a significant increase in components with <100> directions in the sheet plane, which are desired for NO steels because they are parallel to the direction of easy magnetization. Heat treatment has also increased the average grain size of the samples from 18 to 128 μm. Magnetic properties are analyzed over a wide frequency range and induction, presenting different behaviors in permeability and magnetic loss for the samples before and after heat treatment. The components of total magnetic loss are also evaluated, and the hysteresis loss of heat‐treated sample decreases significantly. This demonstrates that heat treatment reduces microstructural imperfections, causing a decrease in hysteresis losses. Therefore, it is concluded that the improvement in magnetic performance observed with heat treatment has its origin in the increase in fiber components related to the <100> directions and a decrease in microstructural imperfections.

Influence Mechanisms of Cold Rolling Reduction Rate on Microstructure, Texture and Magnetic Properties of Non-Oriented Silicon Steel

The effects of cold rolling reduction on the microstructure, recrystallization behavior, and magnetic properties of 3.0%Si-0.8%Al-0.3%Mn steel were studied by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). With the reduction rates of 78%, 85% and 87% in the cold rolled sheet, the width of the deformation band becomes narrower, the number of intragranular shear bands decreases, and the proportion of grain boundaries increases. The intensity of the α and γ fibers texture in the cold rolled sheet is enhanced, and the annealed sheet is dominated by the γ fibers texture and the content increases from 26.0% to 34.5%. During the recrystallization process, the Goss and γ-grains nucleate first. The λ-grains nucleate mainly at the grain boundaries of the deformed α-grains, and the α-grains ultimately recrystallize. With the increase in the cold rolling reduction rate, the γ-grains develop into the main texture due to a large amount of nucleation at the deformation band and grain boundary. The λ-grains with a high mobility do not have a numerical advantage, and the increase in the texture content is very small. The content of the unfavorable γ fiber texture in the annealed sheet increases, the magnetic induction intensity B50 decreases, Pe and Pt decrease significantly, and the critical grain size with the lowest iron loss decreases from 136.2 to 109.4 μm.

Effect of high magnetic field annealing on microstructure, texture, and properties of high-strength non-oriented silicon steels

The challenge in high-strength non-oriented silicon steel is the synergistic enhancement of both strength and magnetic properties, which are both significantly influenced by microstructure and texture of the steel. To address this, a novel high magnetic field annealing was employed to modify the microstructure and texture of the steel, aiming for a concurrently optimization of these properties. The results indicated that both the iron loss and strength decreased with increasing annealing temperature, whereas the magnetic induction intensity increased firstly and then decreased. The application of a high magnetic field meaningfully enhanced the magnetic properties of non-oriented silicon steel, whereas the strength of the steel was significantly decrease at 750 °C, but this decrease was reduced at higher temperature. The application of magnetic field reduced the Gibbs free energy of the system during the recrystallization process resulting in a facilitation of recrystallization. During low-temperature annealing (750-800 °C) in the high magnetic field, the dislocation density decreased, and internal stress was reduced, leading to a significant reduction in hysteresis loss and an improvement in magnetic properties. However, the reduction in dislocation density resulted in a substantial deterioration of strength at low temperature. With increasing annealing temperature, the enhanced grain growth with the application of magnetic field lead to an increase in magnetic induction intensity, whereas the grain boundary strengthening contribution decreased, resulting in a decrease in strength. Furthermore, the optimal comprehensive properties were achieved by annealing at 850 °C with a high magnetic field, which yielded a magnetic induction intensity B5000 of 1.679 T, a high-frequency iron loss P1.0/400 of 21.44 W/Kg, and a yield strength of 508 MPa, are well-suited for utilization in the drive motors of new energy vehicles.

A Study on Enhancing Axial Flux Motor Efficiency Using Cladding Core Technology

With the rise of eco-friendly policies, advanced motor technologies are being developed to replace fossil fuel-based engines in the mobility industry. Axial flux motors, known for their ability to reduce size and increase output torque compared to radial flux motors, require different materials and manufacturing techniques. Specifically, the production of complex stator cores and segmented magnets presents significant challenges, often leading to higher costs. To address this issue, soft magnetic composite (SMC) materials, which offer greater design flexibility, are being explored for use in stator cores. However, soft magnetic composite materials exhibit lower permeability and saturation flux density compared to laminated silicon steel, resulting in reduced output torque and efficiency. This paper investigates the effects of stator geometry on axial flux motor performance and explores cladding core technology, which combines soft magnetic composite materials with silicon steel. By conducting finite element method (FEM) analysis to evaluate the output torque and efficiency based on the shape of the silicon steel within the cladding core, this study proposes an optimized cladding core design to enhance the efficiency and output torque of axial flux motors.

Effect of Heat-Treatment Process on Magnetic Characteristics of Grain-Oriented Electrical Steel

This paper explores the effects and impacts of the metallurgical process of quenching on grain-oriented strips of electrical steel. Experimental findings reveal that quenching resulted in increased hardness and an increased Young’s modulus. An analysis of the material structure post-quenching indicates significant alterations in grain spacing and reduced height differences between grains. However, the magnetic properties of the steel deteriorated following quenching.

Effects of Continuous Rolling and Reversible Rolling on 2.4% Si Non-Oriented Silicon Steel

Effects of Continuous Rolling and Reversible Rolling on 2.4% Si Non-Oriented Silicon Steel

Densities, Surface Tensions, and Viscosities of Molten High‐Silicon Electrical Steels with Different Silicon Contents

Density, surface tension, and viscosity of various liquid electrical steels are measured at different temperatures, varying in their silicon content between 3 and 6 mass%. Density and surface tension are determined using the maximum bubble pressure method, while viscosity is investigated comparatively using a vibrating finger viscometer and an oscillating crucible viscometer. The results are compared with models known from the literature. Based on this, the density of the steel [ρ] = kg m−3 and the surface tension [σ] = N m−1 can be described as a function of temperature [θ] = °C and silicon content [Si] = mass% using the equations: , . There is a lack of experimental data in the literature for high‐temperature thermophysical properties for electrical steels. This underlines once again the novelty and significance of this study, as the determined thermophysical properties are essential for a wide range of applications. For instance, they are crucial in the production of metallic powders for additive manufacturing by atomization to adjust the properties of the powders precisely. The findings are also important for steelmaking itself, as the corrosion behavior of refractory material can be better determined.

Ultra‐Thin 3.5%Si Steel with Both Magnetic Properties and Mechanical Properties Produced by Different Process Routes of Large‐Scale Production

The microstructural and textural evolution, as well as the recrystallization kinetics under different cold‐rolling methods and their influencing mechanism on the properties of the thin‐gauge 3.5%Si nonoriented silicon steel, are investigated by electron backscattering diffraction, X‐ray diffractometer, tensile, and magnetic properties test. The results indicate that compared with the primary cold‐rolling process, the reduction rate of secondary cold‐rolling process is lower (58.3%), and many shear bands are formed in the coarse cold‐rolled sheet, which leads to the formation of strong Goss and cube texture after recrystallization annealing. Owing to the high annealing temperature, the average grain size of finished annealed sheet is little different under different cold‐rolling processes, so the mechanical properties and high‐frequency iron loss are basically the same. The iron loss of the secondary cold‐rolled products decreases with an increase in frequency, and the improvement in the iron loss of the high field (1.5 T) becomes larger than that of the low field (1.0 T). Given the high anisotropy index of the Goss texture, the iron loss anisotropy of the secondary cold‐rolled sheet is higher. Considering the magnetic and mechanical properties, the optimum process is the secondary cold rolling with the intermediate annealing temperature of 900 °C.

On the influence of austenite content in orientation selectivity and shear texture evolution during hot rolling of Fe-3 wt% Si grain-oriented electrical steel

A systematic investigation of the development of shear textures during hot rolling of Fe – 3 wt% Si steel has been carried out in the present work with a special focus on the influence of austenite in preferential orientation selectivity. This orientation selectivity was anticipated owing to the fact that texture evolution during thermomechanical processing is entirely an effect of crystallographic rotations and such rotations may experience constraining effects because of surrounding austenite. The influence of austenite on shear texture evolution was studied over a range of finish rolling temperatures (FRTs). The evolution of microstructure and microtexture within the surface-subsurface zone was studied adopting EBSD. Sharp Goss orientation was observed at lower FRT, while texture intensities of Brass and Copper were observed to be high at higher FRT. Additionally, it was inferred that in the surface-subsurface zone, next to the austenite, the ease of rotation about ND contributed to the higher observed frequency of the Brass orientation despite of its overall lesser fraction as compared to Copper orientation. The less observed frequency of Copper orientation near the austenite has been attributed to the resistance offered by the austenite to its adjacent ferrite grains while rotating about TD. This constraining effect of austenite has been shown to be consistent over the entire range of studied FRTs. Moreover, it has been shown that at higher rolling temperatures, the lower constraining effect by austenite paves the way for Goss orientation formation, which acts as the precursor to the formation of Brass at the FRT.

Effect of hot rolling reduction process on macro-inclusion in high silicon steel plates: A numerical study

Inclusions inevitably exist in steel plate, whose behaviour during rolling severely affects the quality of product. In this article, a finite element method was used to simulate the hot rolling behaviour of hard and soft inclusions in high silicon steel plates at different sizes, positions and shapes (circle and square) when the adhesion to the matrix were weak. The shape, relative position and dimensions around the inclusions after rolling were obtained. When the inclusions are hard, cracks are produced around the inclusions after rolling. When inclusions are soft, there are no cracks around the inclusions. Large hard inclusions are more likely to move to the plate surface. When the inclusions are in the position of 1/16 of the sheet, the relative distance between the inclusions and the surface of the sheets is significantly reduced, from 0.062 at the beginning to less than 0.02. Furthermore, the effect of the size and location of hard inclusions on the microscopic defects produced after rolling is discussed. The microscopic defects around the inclusions increase with increasing size and decreasing distance of the inclusions.

Shape Design Optimization and Comparative Analysis of a Novel Synchronous Reluctance Machine With Grain-Oriented Silicon Steel

Shape Design Optimization and Comparative Analysis of a Novel Synchronous Reluctance Machine With Grain-Oriented Silicon Steel

PMSM Design for Elevators: Determination of the Basic Topology Affecting Performance

In recent years, with the increase in high-rise building construction, there has been a rise in demand for elevators. This demand has spurred mutual growth between the vertical transportation sector and high-rise building construction. Both sectors are improving technology, security, and comfort standards. Traditional elevator traction machines typically employ asynchronous motors coupled with geared reducers, despite their low energy efficiency and requirement for large machine rooms. However, with the proliferation of rare-earth magnet materials and advancements in driver technologies, the use of Permanent Magnet Synchronous Motors (PMSMs) in elevator traction machines has increased. PMSMs operate with direct drive, eliminating the need for reducers. High efficiency and passenger comfort are crucial parameters for elevator traction machines. This study focuses on identifying the fundamental topology that could influence the performance of PMSMs for gearless elevator machines. Factors such as stator materials, rotor structures, permanent magnets, winding configurations, slot/pole combinations, cogging torque and torque ripple have been examined to select suitable design topologies for elevator motors. Important topics such as the magnetic properties of grain-oriented silicon steel sheets used in stator construction, B-H curves, lamination forming and stacking factors have been addressed. Two different rotor topologies and magnet arrangements, namely internal and external, have been investigated in PMSM designs. Additionally, the use of four different magnet materials, namely AlNiCo, Ferrite, NdFeB, and SmCo have been compared for PMSM traction motors in elevators. Single-layer and double-layer winding configurations, distributed and concentrated winding configurations have been compared. Fractional slot/pole combinations, which directly affect the performance and comfort of PMSMs, have also been examined based on information obtained from the literature. Particularly, structures with high winding factors, such as 12/10, 12/14, 18/16, 18/20, 24/22, and 24/26 have been identified. Finally, studies on skewing to reduce cogging torque and torque ripple have been addressed.

Study on solidification organization and phase formation of Fe-6.5wt.%Si high silicon steel by arc melting and heat treatment

Abstract The solidification microstructure and phase formation behavior of Fe-6.5wt.%Si high silicon steel was investigated using arc melting and heat treatment. The alloy phase composition and microstructure were analyzed by XRD and SEM. The magnetic performance was measured at a high- and low-temperature vibration sample magnetometer. The results show that the temperature gradient causes alloy ingot to be roughly divided into three layers. With the decrease in temperature, from the bottom to the top, the phase morphology is fine crystals, columnar internal dendrites, and isoaxial internal dendrites. In the annealing ring ingot, the inner dendrites disappeared, and from the bottom to the top of the sample, the microstructure changed from fine crystal, columnar crystal, and isoaxial crystal, to micro-cracks, which first increased and then reduced. The hysteresis loop curve width of the alloy is narrow, the slope is large, the hysteresis is 0.126 emu/g, and the magnetic utilization after annealing decreases to 0.0667 emu/g, but the coercive force increases to 2.8 Oe/g, and the annealed alloy is more sensitive to the magnetic field and has a high magnetic conductivity coefficient.