Search Results (77)

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

Magnetic Barkhausen noise (MBN) analysis is a non-destructive evaluation technique that offers significant advantages in assessing the magnetic properties of electrical steels. It is particularly useful for quality control in electrical steel production and for evaluating magnetic quality during core manufacturing and assembly. Despite its potential, MBN has not been widely used in electrical steel characterization. One obstacle is that the effects of silicon content in the electrical steel and the residual stress generated during its processing on MBN have not been thoroughly understood, limiting the practical application of the MBN technique in the electrical steel and electric motor industries. To address this knowledge gap, this paper investigates the MBN responses from four non-oriented electrical steel (NOES) sheets with varying silicon contents (0.88, 1.8, 2.8, and 3.2 wt%) but similar other elements. The measurements were performed both with and without applied tensile stress. It is observed that increasing the Si content increases the pinning density, which, together with the microstructure and texture, largely impacts the MBN response. In addition, the MBN energy increases with the applied stress, which can be attributed to the increase in the number of 180° domain walls (DWs) in the direction of stress. The rate of this MBN increase, however, differs among steels with different silicon concentrations. This difference is due to the combined effect of the DWs and pinning density. When the DW spacing becomes less than the jump distance between the pinning sites, no further increase in the MBN energy is observed with additional stress. The reported results provide a basis for the interpretation of MBN signals for varying wt% Si in NOES when residual stresses are present. 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

The production of silicon steel involves complex metallurgical processes, where the kind, composition, size, and quantity of the inclusions generated affect the silicon steel properties. This article is based on the smelting process for W350 non-oriented silicon steel produced by a certain factory. By systematically sampling, at key nodes of the converter–RH refining–tundish smelting process, the change in cleanliness of molten steel in the whole smelting process, the evolution of typical inclusions, and the transformation rules for the precipitated phase were analyzed by means of SEM-EDS, ASPEX, and Thermal-Calc. The results indicate that the total oxygen mass fraction in the steel decreases by more than 95% after deoxidation alloying, and the average oxygen mass fraction in the RH outbound steel is 0.0012%. While the nitrogen mass fraction shows a rising trend as a whole, the average nitrogen mass fraction in the tundish steel reaches approximately 0.0014%. Before RH refining, large Al₂O₃–CaO–SiO₂ and Al₂O₃–CaO–SiO₂–MgO composite inclusions are the main inclusions. MnO and Al₂O₃–SiO₂–MnO inclusions are the main inclusions after RH inlet and RH decarburization. After RH deoxidation with aluminum, the inclusions were almost entirely transformed into Al₂O₃ inclusions. After RH alloying, with the content of Si and Mn increased, the inclusions transformed into Al₂O₃–SiO₂–MnO inclusions. The number of inclusions from RH desulfurization to the RH outbound stage declined significantly, and composite inclusions containing CaS and precipitates such as AlN and MnS began to appear. The inclusions’ main types were Al₂O₃–MgO–CaS, AlN–MnS, AlN, and Al₂O₃–MgO. The inclusions inside the tundish were the same, but the numbers were slightly increased due to the secondary oxidation of molten steel. More than 80% of the oxide inclusions in the whole process were between 1 μm and 5 μm in size. The average size and the number of inclusions per unit area reached 5.45 μm and 63.1 per mm², respectively, after RH deoxidation, and respectively decreased to 3.71 μm and 1.9 per mm² during the RH outbound stage, but both increased slightly in the tundish. Thermodynamic calculation shows that Al₂O₃–MgO inclusions are formed when w([Mg]) > 0.0033% in molten steel at 1873 K. Under the actual temperature of 1828K and w([Al]s) = 0.6515%, the range of w([Mg]) corresponding to the stable existence of Al₂O₃–MgO is between 0.0053% and 0.1676%. The liquidus temperature of W350 non-oriented silicon steel is 1489 °C. MnS and AlN inclusions are precipitated successively with the solidification of molten steel, and the precipitation temperatures are 1460.7 °C and 1422.2 °C, respectively. As the temperature decreases, the sequence of inclusion precipitation calculated in liquid was as follows: Al₂O₃–CaO → 2Al₂O₃–CaO + MnS → 6Al₂O₃–CaO → Al₂O₃ + AlN + MnS + CaS. 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

Chromium salt fillers commonly used in current anti-corrosion coatings are highly toxic. However, due to the unique high–low valence transformation and passivation mechanisms of chromium-based functional fillers and their wide applicability, chromium-free coatings find it challenging to achieve the same performance and industry acceptance. This study introduces an innovative approach that uses zinc to reduce molybdate (MoO₄²⁻) in an acidic solution, thereby forming a multivalent MoO₄²⁻ system (PMZ system), and applies it to chromium-free insulating coating for oriented silicon steel. The effects of reductant dosage on the valence composition of molybdenum in the PMZ system and the corrosion resistance of the coating were investigated. Additionally, the difference in the valence composition of molybdenum between the PMZ system and the multivalent phosphomolybdate system (PMNZ system) and its impact on corrosion resistance were studied. The results indicate that the PMZ system contains trivalent molybdenum and hexavalent molybdenum, while the PMNZ system contains pentavalent molybdenum and hexavalent molybdenum. The systems leverage the reactivity of lower-valence molybdenum to delay the corrosion by reacting with oxygen while maintaining the original mechanism of molybdenum salt fillers and forming sediment with iron ions to form a passivation layer. As the content of trivalent molybdenum in the PMZ system increases, the corrosion resistance of the insulating coating improves. When the amount of zinc added in the PMZ system is 0.006 g, the relative proportion of trivalent molybdenum reaches 20.52%, and the salt spray resistance of the coating developed with the PMZ system reaches 248 h with a corrosion area of less than 5%. When the contents of the main components and sodium molybdate in the PMZ coating and the PMNZ coating are the same, the corrosion resistance of the PMZ coating, which contains trivalent molybdenum, is better than that of the PMNZ coating, and the salt spray resistance exceeds 192 h. 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

Molybdenum disulfide is a 2D material with excellent lubricant properties, resulting from weak van der Waals forces between lattice layers and shear-induced crystal orientation. The low forces needed to shear the MoS₂ crystal layers grant the tribological system low coefficients of friction (COF). However, film oxidation harms its efficacy in humid atmospheres, leading to an increased COF and poor surface adhesion, making its use preferable in dry or vacuum conditions. To overcome these challenges, doping MoS₂ with elements such as Nb, Ti, C, and N emerges as a promising solution. Nevertheless, the adhesion of these coatings to a steel substrate presents challenges and strategies involving the reduction in residual stresses and increased chemical affinity to the substrate by using niobium-based materials as interlayers. In this study, Nb-doped MoS₂ films were deposited on H13 steel and silicon wafers using the pulsed direct current balanced magnetron sputtering technique. Different niobium-based interlayers (pure Nb and NbN) were deposited to evaluate the adhesion properties of Nb-doped MoS₂ coatings. Unlubricated scratch tests, conducted at room temperature and relative humidity under a progressive load, were performed to analyze the COF and adhesion of the coating. Instrumented indentation tests were conducted to assess the hardness and elastic modulus of the coatings. The microstructure of the coatings was obtained by Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and Transmission Electron Microscopy (TEM), with Energy-Dispersive X-Ray Spectroscopy (EDS). Results indicated that niobium doping on MoS₂ coatings changes the structure from crystalline to amorphous. Additionally, the Nb concentration of the Nb:MoS₂ coating changed the mechanical properties, leading to different cohesive failures by different loads during the scratch tests. Results have also indicated that an NbN interlayer optimally promoted the adhesion of the film. This result is justified by the increase in hardness led by higher Nb concentrations, enhancing the load-bearing capacity of the coating. It is concluded that niobium-based materials can be used to enhance the adhesion properties of Nb-doped MoS₂ films and improve their tribological performance. Full article

In the context of rising power densities in electrical machines, additive manufacturing presents an opportunity to develop more powerful thermal solutions. However, the physical properties of objects manufactured using this process remain unclear. This research examines the directional thermal and electrical conductivities of aluminum alloy (AlSi10Mg) and silicon steel (Fe-3.7%wt. Si) samples produced via laser powder bed fusion (LPBF), both prior to and following heat treatment. The findings indicate that the as-built aluminum samples exhibit higher conductivities in the orientation parallel to the LPBF build direction, while annealing results in higher conductivities overall and an absence of anisotropy. On the other hand, the silicon steel samples show constant conductivities and lack of anisotropy both before and after heat treatment. These results have practical applications in the design of additively manufactured electrical machines, where the thermal and electrical resistance of the materials have a major impact on thermal and electromagnetic performance. Full article

In order to study the texture evolution and the formation of an inhomogeneous microstructure in hot-rolled plate of grain-orientated silicon steel, Fe₃C (hexagonal) and ferrite phases in the subsurface layer were studied using electron backscatter diffraction. The results indicate that fiber texture (ferrite) mainly composed of {441}<104> and (110)[001] Goss oriented grains was formed at a depth of 25% of the thickness of hot-rolled plate. Matrix grains in the subsurface layer were arbitrary separated into irregular large grains (≥40 μm) and fine grains (<40 μm), and the grain boundary characteristics and texture evolution of matrix grains were studied. The results indicated that the formation of the colonies of fine grains was the result of dynamic recrystallization, and high-frequency low-misorientation-angle boundaries (0~20°) were formed between large grains (≥40 μm) and fine grains (<40 μm), which can be considered as the irregularity of large grains caused by solid-state wetting. Due to the texture evolution of large grains (≥40 μm), a large number of high-energy boundaries (20~45°) were formed between irregular large grains (≥40 μm), resulting in rapid consumption between adjacent large grains and the elongation of large grains along the rolling direction. Therefore, it can be assumed that the migration of low-misorientation-angle boundaries (0~20°) under solid-state wetting and high-energy boundaries (20~45°) are important mechanisms for non-uniform grain growth in hot-rolled plate of grain-orientated silicon steel. Full article

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. Full article

An excellent Fe-3.3 wt% Si steel was fabricated by double cold rolling and final annealing. The evolution of the microstructure and texture was studied by optical microscope (OM), X-ray diffraction (XRD), ex situ, and quasi-in situ electron backscattered diffraction (EBSD) to investigate the recrystallization behavior. Double cold rolling significantly reduced the adverse γ texture in the final annealed sheets, and a stronger η texture was observed. With a reduction ratio of 50% and 65% during double cold rolling, the γ texture almost disappeared, whereas the η texture was obviously improved. Consequently, the texture factor reached its peak, leading to a reduction in iron loss and an enhancement of magnetic induction. By combining texture regulation with dislocation strengthening, the magnetic properties of Fe-3.3 wt% Si steel were improved, and the yield strength also increased. The final sheet exhibiting exceptional magnetic characteristics and enhanced strength attained a reduction in iron loss (P_10/400 = 21.84 W/kg) of 6.43 W/kg, along with an enhancement of magnetic induction (B₅₀ = 1.698 T) of 0.038 T and yield strength (R_p0.2 = 578 MPa) of 37 MPa compared to a single-stage cold rolling process. Full article