Search Results (59)

In the manufacturing process of high-grade non-oriented electrical steel, cast billets are subjected to hot rolling and normalizing treatments. These processes are implemented to optimize the microstructure and texture of steel sheets during production, mitigate corrugated defects, and enhance the magnetic properties of the final finished sheets. In this study, two types of high-strength non-oriented silicon steel test specimens were prepared via the incorporation of the trace alloying element Sn, namely one without Sn addition and the other with 0.045 wt% Sn. The test specimens were first hot-rolled to a thickness of 2.0 mm, followed by normalization treatment in the laboratory to simulate the continuous normalizing process employed by a domestic steel mill. The effects of Sn on the normalized microstructure, texture, and precipitates of non-oriented silicon steel tailored for new energy vehicles were investigated. The findings reveal that the alloying element Sn can increase the thickness of the recrystallized layer on the surface of hot-rolled sheets and refine the grain size of non-oriented silicon steel. After continuous normalizing treatment, a comparison between the two test specimens shows that as the normalizing temperature rises, the reduction in average grain size of the 0.045 wt% Sn specimen relative to the Sn-free specimen increases from 1.4% to 15.96%. Additionally, the incorporation of Sn reduces the fraction of the {111} texture component (detrimental to magnetic properties) while increasing the fraction of the {100} texture component (beneficial to magnetic properties) in the non-oriented silicon steel. Precipitates exhibited significant coarsening and a reduction in number with increasing temperature, while the addition of Sn exerted a certain inhibitory effect on precipitate growth. Furthermore, the 0.045 wt% Sn-containing test specimen achieved an optimal balance between magnetic and mechanical properties when subjected to normalization at 980 °C and annealing at 920 °C. Under these processing conditions, the magnetic induction B₅₀ reached 1.733 T, the iron loss P_1.5/50 was 2.01 W/kg, the yield strength was 410 MPa, and the tensile strength was 529 MPa. Full article

DC bias is a primary cause of anomalous vibration and noise in power transformers. This study investigates the magnetostriction characteristics of grain-oriented silicon steel sheets under simultaneous AC excitation and DC bias. A novel prediction method is proposed, which integrates multi-scale mutual information features with frequency-domain features, and employs a long short-term memory (LSTM) network for DC bias identification. The experimental platform with six voltage levels and seven bias ratios was set up to collect strain signals under various operating conditions. The results indicate that DC bias alters the magnetostriction spectrum by modulating the nonlinear response. Specifically, the amplitude of the 100 Hz harmonic decreases monotonically as bias increases, whereas the high-frequency harmonics are noticeably amplified, leading to greater waveform asymmetry and harmonic distortion. The proposed prediction model achieves a root-mean-square error (RMSE) of 0.0336 and a coefficient of determination (R²) of 0.8810 under stratified 5-fold cross-validation, offering theoretical support and experimental evidence for DC bias monitoring and transformer condition assessment. Full article

One promising innovative joining process for non-oriented electrical sheets is based on an electro-insulating layer combined with a self-bonding varnish. The aim of this study was to investigate the adhesion of the self-bonding varnish as evaluated by a lap-shear test. During the experiments, non-oriented electrical steels with low to high silicon content were analyzed and tested. The Si content, the bond thickness, and the surface roughness Ra, as well as the selected steel production parameters—such as the radiation tube furnace temperature (RTF), the grain growth temperature (i.e., heating temperature (HF)), the peak metal temperature (PMT), and the annealing atmosphere (dry or humid, controlled by dew point)—were considered as the variables. The results showed that the lap-shear strength was independent of the surface roughness within the investigated range. In contrast, the bond thickness exhibited a weak positive effect on the lap-shear strength, while the Si content showed condition-dependent behavior. The RTF and the HF resulted in a relatively stable mechanical performance, whereas the PMT and the humid annealing atmosphere were identified as critical factors influencing adhesion. Full article

This study systematically investigated the influence of annealing tension on the microstructure, texture, and magnetic properties of ultra-thin grain-oriented silicon steel, which is of great significance for achieving the preparation of high-quality ultra-thin grain-oriented silicon steel. The research indicates that tension primarily affects the magnetic properties by influencing the intensity of the η-fiber texture (<001>//RD) and the grain size during the annealing process, exhibiting a consistent trend across different annealing temperatures. That is, the proportion of η-oriented grains (or the intensity of the η-fiber texture) first decreased and then increased with increasing tension. Correspondingly, the magnetic induction (B₈₀₀) decreased initially and then increased with the rise in annealing tension. Specifically, when annealed at 800 °C for 30 min, B₈₀₀ decreased to 1.79 T under 24 MPa tension and then recovered to 1.86 T under 40 MPa tension. When annealed at 775 °C for 30 min, B₈₀₀ decreased to 1.81 T under 24 MPa tension and subsequently recovered to 1.88 T under 40 MPa tension. In terms of grain size, the annealing tension promoted an increase in the average grain size. The synergistic effect of microstructure and texture led to a trend where the iron loss value (P_1.5/400) of the ultra-thin strip under tension first increased and then decreased: when annealed at 800 °C for 30 min, the iron loss initially increased to 14.68 W/kg and then decreased with increasing tension; similarly, when annealed at 775 °C for 30 min, the iron loss first increased to 18.81 W/kg and then decreased with increasing tension. The evolution of the microstructure and texture is determined by the competition between the nucleation and growth of η-oriented grains and other grains during recrystallization: in the nucleation stage, the annealing tension reduced the strong advantage of η-oriented grains to some extent; however, it is speculated that η-oriented grains possess an advantage during the grain growth stage. Full article

Non-oriented (NO) Fe–Si electrical steels are key materials for magnetic cores of electrical machines, requiring a balance between magnetic and mechanical properties. This study systematically examined the effect of silicon content (1.06 wt%, 2.15 wt%, and 3.09 wt%) on the microstructure, mechanical, and tribological behavior of three produced NO steel grades. Mechanical properties were assessed using tensile tests, microhardness, and nanoindentation, while tribological performance was evaluated under dry reciprocating sliding (ball-on-flat) against a 100Cr6 steel ball at loads of 5 N, 10 N, and 25 N. Increasing silicon content led to larger grain size, higher hardness (227 HV–361 HV) and strength, but lower ductility. Tribological behavior depended on both composition and load. The most stable friction regime occurred at 10 N. The medium-Si steel (N3, 2.15 wt%) exhibited the best performance with a low coefficient of friction (COF ≈ 0.52–0.55); N5 (3.09 wt%) showed a similar COF, while N1 (1.06 wt%) had a slightly higher value. At 25 N, an inverse relationship between hardness and friction appeared: softer N1 had the lowest COF (≈0.68–0.70), whereas harder N3 and N5 reached ≈ 0.74–0.78. Scanning electron microscopy (SEM) observations revealed abrasive wear for N3/N5 and plastic flow (galling) for N1. Overall, an optimal silicon content provides the best compromise between hardness and tribological stability depending on load conditions. Full article

Improving the efficiency of electric vehicle traction motors requires non-oriented silicon steels with low core loss and favorable magnetic induction. This study aims to clarify the influence of annealing temperature on the microstructure, texture, and magnetic properties of a 3.2%Si–0.9%Al steel, providing guidance for process optimization. Optical metallography, X-ray diffraction, and electron backscatter diffraction were employed to characterize the evolution. Recrystallization was completed between 620 °C and 720 °C, during which fine recrystallized grains replaced the deformed structure, accompanied by the nucleation of {111}<112> and {114}<481> grains. With further annealing from 850 °C to 1050 °C, grain growth occurred, resulting in an α*-fiber texture dominated by {114}<481>. The fraction of high-angle {114}<481> grains increased, while low-angle {111}<112> grains decreased. This microstructural evolution significantly influenced the magnetic properties of non-oriented electrical steel. The P_1.5/50 and P_1.0/400 core losses reached minimum values of 2.02 W/kg and 16.48 W/kg at 1010 °C and 930 °C, respectively, while B₅₀ decreased slightly from 1.670 T to 1.652 T. These findings indicate that precise control of the annealing temperature is an effective strategy to tailor microstructure and texture, thereby optimizing the magnetic properties of non-oriented electrical steel. Full article

Improving the isotropic magnetic properties of FeSi electrical steels has traditionally focused on enhancing their crystallographic texture and microstructural morphology. Strengthening the cube texture within a ferritic matrix of optimal grain size is known to reduce core losses and increase magnetic induction. However, conventional cold rolling followed by annealing remains insufficient to optimise the magnetic performance of thin FeSi strips fully. This study explores an alternative approach based on grain boundary migration driven by temperature gradients combined with deformation gradients, either across the sheet thickness or between neighbouring grains, in thin, weakly deformed non-oriented (NO) electrical steel sheets. The concept relies on deformation-induced grain growth supported by rapid heat transport to promote the preferential formation of coarse grains with favourable orientations. Experimental material consisted of vacuum-degassed FeSi steel with low silicon content. Controlled deformation was introduced by temper rolling at room temperature with 2–40% thickness reductions, followed by rapid recrystallisation annealing at 950 °C. Microstructure, texture, and residual strain distributions were analysed using inverse pole figure (IPF) maps, kernel average misorientation (KAM) maps, and orientation distribution function (ODF) sections derived from electron backscattered diffraction (EBSD) data. This combined thermomechanical treatment produced coarse-grained microstructures with an enhanced cube texture component, reducing coercivity from 162 A/m to 65 A/m. These results demonstrate that temper rolling combined with dynamic annealing can surpass the limitations of conventional processing routes for NO FeSi steels. Full article

The effects of Cu content on the microstructure, texture, precipitates, and magnetic and mechanical properties of 0.20 mm-thick non-oriented silicon steel (3.0% Si-0.8% Al-0.5% Mn) were systematically investigated using optical microscopy, X-ray diffraction, electron backscatter diffraction, and transmission electron microscopy. The strengthening mechanisms of Cu-bearing high-strength non-oriented silicon steel were further elucidated. Increasing Cu content inhibited grain growth and suppressed the development of the α*-fiber texture in annealed sheets, while promoting the formation of γ-fiber texture. As a result, the P_1.0/400 and B₅₀ values deteriorated. The P_1.0/400 and B₅₀ values of 1.47% Cu non-oriented silicon steel were 13.930 W/kg and 1.614 T, respectively. However, due to the solid solution strengthening effect of 0.5% Cu and partial precipitation strengthening, the R_p0.2 increased by 43 MPa. After aging treatment at 550 °C for 20 min, the P_1.0/400 values of the aged sheets slightly increased, while the B₅₀ values remained almost unchanged. In the aged sheets containing 1.0–1.5% Cu, clustered Cu-rich precipitates with average sizes of 2.71 nm and 13.28 nm were observed. The crystal structure of these precipitates transitioned from the metastable B2-Cu to the stable FCC-Cu. These precipitates enhanced the R_p0.2 of the non-oriented electrical steel to 241 MPa and 269 MPa through cutting and bypass mechanisms, respectively. A high-strength non-oriented silicon steel with balanced magnetic and mechanical properties was developed for driving motors of new energy vehicles by utilizing nanoscale Cu-rich precipitates formed through aging treatment. The optimized steel exhibits a yield strength of 708 MPa, a magnetic induction B₅₀ of 1.639 T, and high-frequency iron loss P_1.0/400 of 14.77 W/kg. Full article

The effects of trace Ce on the microstructure and texture of non-oriented silicon steel during recrystallization and grain growth were examined using X-ray diffraction and electron backscatter diffraction. Additionally, this study focused on investigating the mechanisms by which trace Ce influences the evolution of the {114} <481> and γ-fiber textures. During the recrystallization process, as the recrystallization fraction of annealed sheets increased, the intensity of α-fiber texture decreased, while the intensities of α*-fiber and γ-fiber textures increased. The {111} <112> grains preferentially nucleated in the deformed γ-grains and their grain-boundary regions and tended to form a colony structure with a large amount of nucleation. In addition, the {100} <012> and {114} <481> grains mainly nucleated near the deformed α-grains, which were evenly distributed but found in relatively small quantities. The hindering effect of trace Ce on dislocation motion in cold-rolled sheets results in a 2–7% lower recrystallization ratio for the annealed sheets, compared to conventional annealed sheets. Trace Ce suppresses the nucleation and growth of γ-grains while creating opportunities for α*-grain nucleation. During grain growth, trace Ce reduces γ-grain-boundary migration rate in annealed sheets, providing growth space for {114} <418> grains. Consequently, the content of the corresponding {114} <481> texture increased by 6.4%, while the γ-fiber texture content decreased by 3.6%. Full article

As a critical factor for the magnetic properties of grain-oriented silicon steel, the orientation accuracy of shear bands is closely related to the matrix orientation deviation from {111}<112>. This work investigates the orientation rotation of shear bands in {111}<112> matrices with various types of deviation during cold rolling, using a visco-plastic self-consistent model that incorporates a two-dimensional inclined angle of the shear band dependent on matrix orientation. When the matrix orientation deviates from {111}<112> along φ₁, φ₂, or both axes, the φ₁ deviation of the shear band decreases, and the φ₂ deviation is larger than φ₁. Compared with a uniaxially deviated {111}<112> matrix, a biaxially deviated matrix along φ₁ and φ₂ axes produces a higher shear band deviation from Goss due to the increased φ₂ deviation. This suggests that improving the orientation accuracy of the shear band is necessary to decrease the matrix deviation from {111}<112> in the φ₁ and especially φ₂ axes. Full article

The ongoing electrification process also requires improvements in the efficiency of power transmission devices, such as transformers, the main part of which is the magnetic core. Despite great progress in the development of core material, losses and audible noise during their operation is still a critical issue to be solved. Currently, a magnetic material used to produce the transformer core is amorphous steel, which is gaining popularity. Compared to traditionally used grain-oriented silicon electrical steel, a significantly larger number of very thin amorphous ribbons is needed to produce the core, which is due to the fact that they are about an order of magnitude thinner, making mechanical stability a challenge. The presented article describes the preparation of a hybrid binder for amorphous steel based on the two types of silanes, tetraethyl orthosilicate and 1,2-bis(triethoxysilyl)ethane, for which their anticorrosive character and good dielectric properties were confirmed. Using the obtained binders, model toroidal cores were produced and their magnetic and acoustic properties were tested. The obtained results indicate that the applied silane-based hybrid binders improved important functional properties by reducing the magnetic no-load losses and audible noise. Full article

Industrialization trial production of high permeability (Hi-B) steel was carried out by “one cold rolled + decarburization and nitridation technologies”. The finished product reached the level of 23Q100 with an average grain size of 5.47 cm, magnetic flux density B₈ of 1.902T, and the iron loss P_1.7/50 of 0.975 W/Kg. The evolution law of the microstructure and texture under different processes was analyzed with the help of OM, EBSD, and XRD. The results showed that the microstructure of the hot rolled plate was equiaxed crystals in the surface layer, a mixture of recrystallization grains and banded fiber in the quarter of the thickness layer, and banded fiber in the center layer. The texture gradient of the hot rolled plate from the surface layer to the center layer was {112}<111> + {110}<114> → {441}<014> → {001}~{111}<110>. The texture of the normalized plate was in major {110}<113> in the surface layer, diffuse α-fiber texture and {441}<014> in the quarter of the thickness layer, and sharp α texture {001}~{111}<110> in the center layer. The texture of the cold-rolled sheet was concentrated in {001}~{332}<110>. The average grain size of the decarburizing and nitriding sheet was 26.4 μm, and the texture of the first recrystallization is sharp α*-fiber and weak {111}<112>. The finished product has a sharp single Goss texture. For Hi-B steel, the Goss secondary nucleus originated from the surface layer to 1/4 layer of the hot rolled plate and reached the highest content of 11.5% in the quarter of the thickness. The content of the Goss texture decreased with the subsequent normalization and cold rolling, then the Goss grains nucleated again during the decarburization annealing and high temperature annealing processes. Full article

In order to improve the magnetic properties of non-oriented silicon steel, the effects of different normalizing temperatures on the microstructure, texture, and magnetic properties of 3.0%Si 0.8%Al non-oriented silicon steel were studied by OM, EBSD, and a magnetic measuring instrument. The results show that the microstructure of the hot-rolled plate is obviously different along the thickness direction. Strong Goss texture and {001} ~ {112} texture are the main textures in the hot-rolled plate. After normalizing at 900 °C, 940 °C, and 980 °C and annealing at 940 °C, respectively, the average grain size of the normalized plates and the annealed sheets increases with the increase in the normalizing temperature, and the texture types of the normalized plates basically inherit that of the hot-rolled plates. With the increase in normalizing temperature, the intensity of the γ-fiber texture decreases, and the main texture types in the finished plates are {100} <012> texture and {111} <112> texture. The area fraction of {100} <012> texture in the finished sheet normalized at 980 °C and annealed is the largest, which is 20.3%, and the area fraction of {114} <481> texture is larger, which is 15.2%. The magnetic induction B₅₀ of the finished sheets increases gradually with the increase in the normalizing temperature, from 1.662 T to 1.720 T; the low-frequency iron loss P_1.5/50 decreased slightly from 2.46 W·kg⁻¹ to 2.30 W·kg⁻¹. The high-frequency iron loss P_1.0/400 decreased significantly from 17.40 W·kg⁻¹ to 15.75 W·kg⁻¹. The results of the microstructure, texture, and magnetic properties show that the best normalizing temperature in this experiment is 980 °C. Full article

An efficient numerical calculation method of stray-field loss is investigated for typical magnetic load components (grain-oriented silicon steel sheets (GO), magnetic steel plate, and combined components of both materials) under non-sinusoidal excitations (NSE) containing symmetrical harmonic and DC to avoid the local overheating caused by high stray-field loss density. The paper investigates the stray-field loss with different types of load components and working conditions based on the leakage flux complementary-based measurement method, derives an analytical formulation calculating the energetic hysteresis model parameters under different magnetic flux densities to reduce the dependence on measurement data, establishes a loss calculation method considering the influence of non-sinusoidal magnetization on magnetic loss, and discusses the advantages and limitations of existing numerical approaches of additional loss to establish an effective computational strategy of stray-field loss. Finally, the effectiveness of the proposed method is verified by simulations and experiments. Full article

High-grade non-oriented silicon steel with high magnetic induction and low iron loss produced with low carbon emissions is crucial for the development of new energy and energy-saving motors. In this paper, the trace mixed rare earth (RE) elements exhibit a great potential to enhance magnetic properties in a lower carbon emission process by multiple effects on microstructure, texture, and inclusion in non-oriented silicon steel. With the trace-doped RE elements (0.004–0.030%), RE-rich precipitates preferentially form and subsequently adsorb fine inclusions below 1 μm to transform into spherical or ellipsoidal shape, which results in a significant increase in final recrystallization grain size. Moreover, the favorable λ texture (<001>//ND) is promoted while the detrimental γ texture (<111>//ND) is reduced, owing to the advantages in size and quantity of λ grains during the nucleation process. The improved magnetic properties of higher B50 and lower P15/50 are achieved with 0.004% RE at lower annealing temperature ranges. The increased λ texture is attributed to the heterogeneity in microstructure and texture as well as the grain boundary segregation of RE elements. However, a higher RE content (0.072%) leads to a deterioration in magnetic performance due to the formation of more stable RE-rich precipitates, smaller grains, and stronger γ texture. An iron loss calculation model was also proposed to guide the design of high-grade non-oriented silicon steel by incorporating the multiple effects of RE elements on grain size, recrystallization texture, and inclusion. Full article