Papers by Keyword: High Silicon Steel

Abstract: High silicon steel was fabricated by twin-roll strip casting. The cracks on the surfaces of the processed strips were obtained and analyzed by digital camera after series of surface treatment. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to observe and characterize the microstructure nearby crack and fracture surface along the normal direction, respectively, and the crack formation mechanism was further analyzed in conjunction with processing parameters utilized during twin-roll strip casting process. The results indicated that morelongitudinal cracks along the rolling direction were observed in comparison with transverse cracks along the transverse direction on the strip surfaces. Trans granular and intergranular fracture modes both worked during the formations of longitudinal and transverse cracks on the processed strips. The dominant factor causing the formation of crack on the surface of the processed strips was the inhomogeneous transfer of heat during casting and rolling. The inhomogeneous transfer of heat induced by gas gap during casting resulted in variations of dendrite length and secondary dendrite spacing (SDAS). Meanwhile, the casting velocity influenced the formation of gas gap, which further influenced the thermal contraction. So the control of velocity of casting above a certain level proved beneficial to enhancing the performance of strip casting and to improving the quality of strip products.

Abstract: Combining ferrosilicon alloy with electro-deposition method, the main phase in the deposit layer is Fe3Si, and the substrate texture is mainly distributed in γ orientation line, {111}<110> and {111}<110> is the key component. The sample is mainly the cubic texture of {100}<001> and {111}<112> in γ orientation line, with a small amount of Goss texture. {111} texture share in the sample decreases.

Abstract: Fe-6.5%Si alloy is an excellent soft magnetic material. However, the industrial production of this sheet was difficult, due to its room temperature brittleness. In order to improve its deformation performance, the directional solidification and inhibitor of Nb were investigated in this study. Rod samples of Φ6.8 mm×100 mm were used both for modeling and experiments. ProCAST-finite element analysis was employed for the modeling with a temperature gradient of 1150K/cm (from 1450°C to 300°C) for directional solidification and the drawing velocities of 10, 35, 60, and 100μm/s. Calculations were carried out on the concerning temperature gradient, solidification rate and grain growth. The results showed that small amount of Nb, with optimized drawing velocity of 60μm/s was helpful for the homogeneity of grain size, which could improve the ductility for subsequent deformation processes.

Abstract: An Fe-6.2wt%Si as-cast strip with equiaxed grains and obvious {001} fiber texture was produced by twin-roll strip casting process. The as-cast strip was successively performed by hot rolling, warm rolling and annealing. The microstructure and texture evolution at each process stage were investigated by using electron backscatter diffraction and x-ray diffraction. It was found that the finally annealed sheet was characterized by large grain size, mild γ-fiber texture and obvious {001} fiber texture. Therefore, a high magnetic induction and a low core loss were obtained in the sheet.

Abstract: 0.2mm-thick high silicon steel thin sheet under 94% cold rolling reductions has been successfully produced by conventional rolling method. Texture evolution during hot rolling, cold rolling and final annealing as well as magnetic properties has been investigated with emphasis on the effect of finishing temperature. It is found that a favorable strong {001}<210> recrystallization texture and evidently improved magnetic properties can be obtained at the finishing temperature of 900°C, which is in contrast with relatively strong detrimental {111}<112> and weak {001}<210> recrystallization texture at the finishing temperature of 700°C. Effects of finishing temperature can be explained in terms of the cold rolling texture due to different texture morphology in hot bands.

Abstract: High silicon steel containing 6.5 wt% Si was prepared by pulse electrodepositon in KCl-NaCl-NaF-SiO₂ molten salt followed by diffusion annealing. The composition, the phase and the evolution of texture during the different production step were analyzed by glow discharge optical emission spectroscopy (GDOES), X-ray diffraction analysis (XRD) and the orientation distribution function (ODF). The results showed that the silicon content of the high silicon steel was about 6.5wt%. The high silicon steel was composed of a-Fe and Fe₃Si. After diffusion annealing the undesirable g-fibre type texture {111} <110> and {111} <112> weakened, both easy magnetization direction Goss texture ({110} <001>) and cube texture {100} <001> were intensified.

Abstract: High silicon steel with Si content of 6.5wt.% is perspective to be applied in magnetic devices at high frequencies. It is very hard to produce Fe-6.5wt%Si alloy thin sheet by conventional hot-cold rolling method because of its embrittlement at room temperature resulted from the formation of intermetallic phases like B2 and D03. In this paper, embrittlement mechanism, rolling processes, and magnetic properties for the cold rolled Fe-6.5wt.% Si alloy sheets are discussed. Our study indicates that thermal mechanical treatments can improve the ductility of the Fe-6.5wt.%Si alloy. The Fe-6.5wt.%Si alloy sheets of 0.05 mm thickness can be successfully obtained after hot-cold rolling and heat treatments. Lamination pieces can be punched directly from the sheets. Tensile strength as high as 1048MPa and elongation over 3% were measured at room temperature.

Abstract: In the process of preparation of high silicon steel by EB-PVD, the effect of distance between ingot and substrate on the weight percent of silicon in the silicon steel was investigated through specially designed experiment. Energy dispersive spectroscopy (EDS), optical microscope (OM), scanning electron microscopy (SEM), x-ray diffraction (XRD) were used to characterize the weight percent of silicon, microstructure, crystal grain size and phase of the high silicon steel. The experimental results show that the weight percent of silicon in the silicon steel decreases with increasing of the distance between ingot and substrate, when the distance is about 415 mm, high silicon steel can be fabricated by EB-PVD. The microstructure of the high silicon steel was composed of columnar crystal grain, the size of the crystal is about 25-50 μm. The material back to the substrate side is composed of B2 and exhibits strong {400} texture.

Abstract: Crystallographic texture has an important effect on the magnetic quality of electrical steel: a specific texture parameter A is defined and used to estimate the magnetic quality of texture components. It is shown that obtaining the best possible texture in non oriented electrical steel can reduce the losses with 1,5 W/kg. Two production schemes for high silicon electrical steel are described: a conventional processing through hot and cold rolling with adequate temperatures and cooling rates and an immersion-diffusion process by hot dipping in a Si- and Al-rich bath followed by diffusion annealing. The texture evolution in these experimental materials is under study and first results are reported for conventional alloys (rolling procedure) and for immersion-diffusion alloys, which are annealed after dipping in order to obtain a controlled concentration gradient with high Si and/or Al at the surface or a homogeneous Si and/or Al-content over the thickness.