Non-oriented Silicon Steel Research Articles

Additive Manufacturing and Testing of a Soft Magnetic Rotor for a Switched Reluctance Motor

Additive manufacturing is acknowledged as a key enabling technology, although its adoption is still constrained to niche applications. A promising area for this technology is the production of electrical machines (EMs) and/or their main components (e.g. magnetic cores, windings, heat exchangers, etc.) due to the potential of creating lightweight, highly efficient rotating motors, suitable for applications requiring a low moment of inertia. This work investigates the readiness of metal additive manufacturing, specifically Laser Powder Bed Fusion (LPBF), applied to the field of EMs to bridge the gaps of how to use this technological approach in this field. A soft magnetic material featuring high silicon content (Fe-5.0%w.t.Si) has been developed for LPBF and a rotor has been 3D-printed for a switched reluctance machine. The printed rotor was assembled into a conventionally laminated stator and the performance of the whole machine was evaluated. Its performance was compared against an identical machine equipped with a laminated rotor of the same dimensions made of conventional non-oriented silicon steel. A comparative study was carried out through both finite element simulations and experimental tests. The efficiency of the two machines was assessed together with the principal electrical and mechanical quantities under several operating conditions.

Thrust analysis of permanent magnet linear synchronous motor with oriented silicon steel

Thrust performance is one of the important indexes of permanent magnet linear synchronous motors. The traditional non-oriented silicon steel sheet is used as the core material of the permanent magnet linear synchronous motor, which limits the performance of the permanent magnet linear synchronous motors. For the oriented silicon steel sheet has a higher magnetic permeability in the rolling direction, a permanent magnet linear synchronous motor with similar number of poles and slots made of oriented silicon steel is proposed in this paper. By measuring the B-H curves of the rolling direction and the cutting direction, the thrust properties of the two motors made of traditional silicon steel sheets and oriented silicon steel sheets are analyzed and compared by the finite element method (FEM) under rated load and overload conditions respectively. The thrusts under different tooth-yoke ratios are discussed in the end.

Pinning field representation using play hysterons for stress-dependent domain-structure model

To predict the stress-dependent magnetization properties of silicon steel using a multiscale magnetization model called assembled domain structure model, pinning field models are developed using the play model. The hysteretic property of pinning field is identified from measured BH loops under stress-free condition. From the unidirectional hysteretic property, the distribution of the play hysterons is determined via an identification method that uses scalar and vector play models under the assumption of 2D or 3D distribution of crystal orientations. The loss properties of non-oriented silicon steel under compressive and tensile stresses are predicted successfully using an energy minimization process without parameter fitting to the stress-dependent measurement results.

Investigation on Inclusions in Non-oriented Silicon Steels

Inclusions in non-oriented electrical steels were automatically measured using Explorer 4 and extracted with a non-aqueous solution electrolytic method to observe their three-dimension morphology. Extracted inclusions were collected and prepared for micro-XRD test, which is performed to identify the crystal structure of inclusions. Inclusions mainly consist of AlN with P63mc structure, MnS with Fm-3m structure and Al2O3 with R-3c structure, and calculated lattice parameters of inclusions almost agree with that listed in standard PDF cards.

Effects of Al content and solidification rate on the crystal orientation of directionally solidified 1.3 wt% Si non-oriented electrical steel

1.3 wt%Si–0.14 ∼ 0.51 wt%Al non-oriented silicon steel as-cast rods with developed columnar structure and pronounced Goss texture were produced using directional solidification technology. The solute enrichments, microstructures and crystal orientations at solid-liquid interface of rods under different solidification rates were investigated. It is found that alloying element Al has little positive branch segregation at solid-liquid interface during equiaxed-to-columnar transformation process. Higher solidification rate is favorable to the homogeneous nucleation of long columnar Goss grains, while higher Al content is beneficial to the stable nucleation and further growth of columnar Goss grain.

The Significance of Microstructure and Texture on Magnetic Properties of Non‐Oriented Silicon Steel: Strip Casting versus Conventional Process

High‐performance nonoriented silicon steel can be produced by the novel strip casting process with a microstructure necessary for magnetic properties. In this regard, the significance of microstructure and texture on magnetic properties of nonoriented silicon steel are comparatively studied in strip‐casting process and conventional hot‐rolling process. The as‐cast strips are uniquely composed of fine equiaxed grains and coarse {100} columnar grains, whereas the hot‐rolled sheets are characterized by fine and uniform microstructure with random orientation. After cold rolling and recrystallization annealing, unfavorable {111} texture dominates the recrystallization texture in the conventional process because of compatible deformation effect of high density of grain boundaries. In contrast, coarse grain with pronounced {100} texture of annealed sheet is obtained via strip‐casting process, which is attributed to strong shear deformation and retention of {100} texture. Considering the synergistic benefits of texture and grain size, nonoriented silicon steel produced by strip casting exhibits superior magnetic properties with low magnetic anisotropy. The magnetic induction of nonoriented silicon steel produced by strip casting is intriguingly 0.06 T higher and the core loss is 0.4 W kg−1 lower than the conventional process. The current study provides practical guidance for processing of nonoriented silicon steel.

Deformation behaviors of non-oriented silicon steel plate in hot rolling process

In this paper, the flow stress behaviors of non-oriented silicon steel are investigated by hot compressive experiments and a constitutive model is built based on the experimental data. The constitutive model provides material model for FE numerical investigation. The deformation behaviors of the non-oriented silicon steel during hot rolling process are investigated by a 3D FE model. Contact stress and plate shape in different working conditions are presented. The FE results can provide primary data for the precise shaping of non-oriented silicon steels in hot rolling process.

The Effect of Annealing Temperature on Recrystallization Texture and Magnetism Property of Non-oriented Silicon Steel under Asymmetrical Rolling Process

The effect of temperature on the recrystallization texture and microstructure of non-oriented silicon steel under asymmetrical rolling condition was studied and the relationship between the magnetism property and recrystallization texture was discussed. The results show that the texture intensity is higher at the fast roller side than that at the slow roller side, but the texture component of recrystallization texture is almost the same under different annealing temperature. At 750 °C, the main texture component is y texture (<111>//normal direction), and the texture (<110>//rolling direction) components become weak. At 850 °C, the main texture components are {111}<110> and {111}<112> texture components. With further increasing of the temperature, the strength of {111}<110> and {111}<112> texture does not change, but they tend to disperse and change to {118} and {1115}, and {001} plane texture. The results also indicate that the annealing temperature has significant influence on the iron-loss, but has no obvious influence on the magnetic induction.

Microstructural evolution and magnetic properties in strip cast non-oriented silicon steel produced by warm rolling

In this study, a specific warm rolling was implemented to process Fe-2.8%Si steel by novel twin-roll strip casting. The impact of warm deformation on mechanical behavior, microstructural evolution and magnetic properties is presented. The study indicated that dynamic strain aging (DSA) occurred in the temperature range of 150–300 °C. The elevated rolling temperature strengthened DSA effect and promoted the formation of shear bands. The nucleation process of Cube ({100} 〈001〉) grains during annealing was weakened on introducing warm rolling, while that of Goss grains ({110} < 001>) was enhanced. Moreover, the recrystallization texture pattern of (Cube + Goss) gradually transformed into a pattern of only pronounced Goss texture. The corresponding values of magnetic induction B50 at rolling direction and transverse direction were obviously improved. This confirms the feasibility of processing ultra-high-permeability non-oriented silicon steel based on twin-roll strip casting combined with DSA-control rolling. However, the rolling process increased the nucleation site for recrystallization and decreased the size of precipitates in annealed sheet, leading to a reduction in grain size and an increase in core loss.

Orientation dependence of strain stored energy and its effect on recrystallization texture in non-oriented silicon steel

Orientation dependence of strain stored energy and its effect on recrystallization texture in non-oriented silicon steel

Symmetry variable taper work roll technology for silicon steel profile control in hot strip mills

ABSTRACT Strip profile control in the hot rolling process plays an important role in guaranteeing high-precision profiles for silicon steel production in cold strip mills. A symmetry variable taper (SVT) work roll for the downstream finishing stands of hot strip mills is designed, which can be used for long stroke reciprocating shifting of work rolls, resulting in decreased edge drop and more uniform work roll wear contour. A finite element simulation model of 4-high mill based on ABAQUS was established, which improved the control characteristics of each process parameter for the strip profile when using the SVT work roll. The actual production data of the 1580 hot strip rolling mill equipped with SVT work rolls showed that the crown C25 of non-oriented silicon steel was reduced by about 5%, the edge drop was reduced by more than 15%, and the crown qualified rate was increased by 10%.

Design of a Three-Phase Reactor Composed of Grain-Oriented Steel Plates for Iron Loss Reduction

To reduce the iron loss of a three-phase reactor composed of grain-oriented (GO) silicon steel plates, we proposed two reactor models. One applies oblique joints between the legs and the yokes, and the other applies butt joints composed of non-oriented (NO) silicon steel plates at the L and T joint parts. The proposed models are aimed to relax the flux concentration inside the iron cores that occurs due to the anisotropic magnetic characteristics of GO silicon steel plates. The effectiveness of the proposed models are investigated through magnetic field and iron loss analyses considering the anisotropic magnetic characteristics of the iron cores. It is found that the flux concentration in the yoke can be relaxed in both proposed models. And iron loss of the proposed model with NO steel plates at the L- and T-shaped joints can be reduced about 12% compared with the ordinary one.

Microstructure and texture evolution of thin-gauge non-oriented silicon steel with high permeability produced by twin-roll strip casting

A new method for producing high permeability thin-gauge non-oriented electrical steels with 2.3 mm thick Fe-3.2% Si steel as-cast strip was studied. The evolution of microstructure and texture was characterized during the entire processing route. Furthermore, the effects of cold-rolling with large reduction and intermediate annealing process on magnetic properties were studied. The results indicated that the as-cast strip with coarse grains exhibited strong λ-fiber. Coarse equiaxed grains with Cube texture were obtained after first-stage cold-rolling with a reduction of 71.74% and intermediate annealing at 900 °C, which promoted the formation of λ-fiber and α-fiber components in the final cold-rolled sheets. {100}⟨0vw⟩ texture was partially retained from the intermediate annealed grains, and new Cube and Goss components were nucleated within {110}〈110〉 shear bands. The magnetic properties of 0.2 mm final sheets were greatly improved by strengthening λ-fiber component with two-stage rolling process, and best magnetic properties were B50 = 1.758 T, P15/50 = 2.065 W/kg, P10/400 = 15.173 W/kg, P10/1k = 59.48 W/kg.

Impact of addition of ca on clogging of SEN and magnetic properties of non-oriented silicon steel

The submerged entry nozzle (SEN) clogging has been happening during continuous casting (or CC for short) for nonoriented silicon steel. To solve the problem, the paper studied a flow rate through SEN, a node attached to one of them, and the impact on the clogging. The results showed that when SEN is clogged seriously, the casting speed has to decrease below the target casting speed and that SEN clogging can be predicted by comparing the actual value and the theoretical one of a casting speed. Al2O3 and its composite inclusions caused the SEN clogging and the addition of Ca can solve SEN clogging during CC of the silicon steel both theoretically and practically. Furthermore, the impact of the addition of Ca on the magnetic properties of the steel were analyzed. The results showed that the core loss and the magnetic induction of the silicon steel decreased by using the addition of Ca, which generated more dissolved Aluminum, and the addition of Ca generated more harmful textures, which reduced the magnetic induction.

Effect of recrystallization annealing temperature on texture and magnetic properties of 2.97% Si non-oriented silicon steel

The effect of recrystallization annealing at temperatures varying from 910 to 1060 °C on the texture and magnetic properties of cold-rolled sheets with 0.3 mm in thickness of 2.97 wt.% Si–0.59wt.% Al non-oriented silicon steel were investigated. With increasing of cold-rolled sheets annealing temperature, the average of the recrystallized grain sizes increased, because of higher temperature corresponds to a faster migration rate of grain boundaries. Increasing of grain size resulted in reducing of the hysteresis loss and core losses, as the number of grain boundary significantly reduced. However, the domain size and the eddy current loss would increase as the grain sizes continued to increase, and then affecting the core losses. The oversized microstructure (∼140 µm) in 1030 °C annealed sheet brought about an augment in P15/50 (∼2.27 W/kg) and (∼130 µm) in 1000 °C annealed sheet of P10/400 (∼12.84 W/kg). Furthermore, the textures of the final sheets were mainly made up of α*-fiber, γ-fiber and {001}&lt;130&gt; texture. The magnetic induction diminished with increasing of annealing temperature and this result could be attributed to the strengthening in γ-fiber (&lt;111&gt;//ND) and weakening in λ-fiber (&lt;100&gt;//ND) texture.

Study on microstructure and texture of a new-type low Si high Mn non-oriented silicon steel 50W250

A new method to fabricate a high grade non-oriented silicon steel was provided, in which the significant feature is low Si high Mn. Metallographic microscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate the microstructure, texture evolution and precipitates characteristics, respectively. It is found that hot rolled sheet had a distinct stratification appearance. Fine equiaxed grains occupy the surface while subsurface and center regions were dominated by deformed microstructure and equiaxed grains. After normalizing, the microstructure of hot rolled sheet completely recrystallized. A number of shear bands were observed attributed to cold rolling. With the increase of annealing temperature or time, the average grain size of final annealed sheet increases. Annealed at 1000 °C for 7 min, annealed sheet exhibits highest and lowest fraction of {001}&lt;100&gt; cube texture and {112}&lt;11-1&gt; copper texture, respectively. The average grain size of final sheet also reaches peak, and it is 117.65 µm. In addition, the fine precipitates mainly include spherical MnS, CuS, regular hexahedral AlN, TiN and partly approximate spherical composite precipitates. The average size and distribution density are 132.10 nm and 1.62 × 1012 cm−3, respectively. Under the condition annealed at 1000 °C for 7 min, the core loss P1.5/50 is 2.461 W · Kg−1 and the magnetic induction B50 is 1.699 T.

Analysis of rate dependency on roll force calculation during hot strip rolling based on Karman equation

Due to the development of thin slab hot rolling technology, hot rolling thin strip at a higher speed is inevitable. As a result of high-speed rolling, thin slab is deformed at a wide range of strain rate inside the rolling zone. Because the flow stress of steel is strongly dependent on strain rate at elevated temperature, it is imperative to consider its variation when calculating roll force and roll pressure. By substituting time with speed and length, strain rate variation is obtained. A strain rate–dependent flow stress curve for non-oriented silicon steel is implemented into Karman equation to calculate rolling pressure distribution. It is revealed that the rolling force can be effectively reduced by decreasing the radius of work roll. It is further revealed that the appearance of strip/roll surface sticking is more likely at the exit of rolling zone than the neutral point, because strain rate reaches zero and the flow stress drops at the exit. Combined with Influence Function Method for elastic deformation of roll surface, the proposed model can predict roll force with a good accuracy compared with industrial data.

A statistical study of inclusions in medium-grade non-oriented silicon steel

There are always differences between the magnetic properties (core loss and magnetic induction) of the head and those of the tail, with the same chemical composition, in a medium-grade non-oriented silicon steel coil (or MGNO for short). To work out the reason leading to the differences and get methods to increase the magnetic properties, this paper studied the types and the distribution of the inclusions in MGNO, and the effects of the inclusions on the magnetic properties of the MGNO, by using SEM + FEEM observation and statistic analysis. The results show that there are oxide inclusions, sulfide inclusions, nitride inclusions and composite inclusions in the MGNO. More inclusions shorter than 500 nm are bad for the magnetic properties of the MGNO. On a lower order of the sizes, the number of the inclusions would more obviously affect the MGNO on its magnetic properties. The Al2O3 shorter than 1 µm and the MnS whose size is 100∼500 nm are the main inclusions that decrease the magnetic properties of the MGNO. In order to get better magnetic properties of the MGNO, the steelmaking process and the hot rolling process should be improved, chiefly the RH and the heat furnace.

Effect of hot band annealing on inclusions, texture, and magnetic properties of 2.97%Si-0.59% Al non-oriented silicon steel

ABSTRACTEffects of hot band annealing on inclusions, texture and magnetic properties of the 2.97%Si-0.59%Al non-oriented silicon steel sheet with 0.3 mm in thickness were investigated by scanning electron microscope and Electron Backscattered Diffraction (EBSD). With the increase of hot band annealing temperature, the inclusions of 0.1–1 μm in hot band obviously reduced, the area fraction of {100}<110> texture prominently increased during recrystallization of hot band. However, the area fraction of {100}<110> dramatically dropped, and α-fibre texture, {111}<112> significantly developed during grain growth of hot band. The texture of the final sheets was dominated by α*-fibre texture, {001}<130> and γ-fibre texture. Furthermore, increasing of hot band annealing temperature increased the grain size, strengthen θ-fibre texture and weaken γ-fibre texture of the final sheets, resulting in the improvement of the magnetic induction and iron loss.

Smart-shifting strategy of work rolls for downstream stands in hot rolling

ABSTRACT In the hot rolling process, the shifting strategy of downstream work rolls has been explored for a long time, as much as possible to guarantee uniformity of roll wear along the width of the strip, thereby improving the steel strip profile. So a smart-shifting strategy based on differentiated step size in the cycle with the sine function is proposed to make the roll wear distribute more evenly, in which a new hybrid optimization algorithm is adopted to find the optimal control parameters. A large number of industrial experiments for the production of non-oriented silicon steel demonstrated that the new strategy was able to improve the wear contour of work roll, and increased the uniformity of the thickness distribution of the strip along the width direction. This has important implications for the improvement of the dimensional accuracy of the strip.