Papers by Keyword: Silicon Steel

Abstract: The simulation studies were carried out on the oriented silicon steel produced by thin slab casting and rolling (TSCR) and twin-roll strip casting in the laboratory. The precipitation of inhibiter, formation of microstructure and texture were investigated before cold rolling. The inhomogeneous microstructure and texture gradient were observed in the 7-pass hot-rolled strip（2mm）for TSCR process, and texture gradient was not changed after normalizing, and the twin-roll strip casting directly supplied a strip with approx 2mm of thickness being same as that of hot-rolled strip by TSCR. The microstructure of twin-rolling casting strip was almost composed of all equiaxed grains which similar to the normalizing microstructure in TSCR process, but the random texture was obtained by twin-rolling strip casting. The dispersed and clustered precipitates were presented in hot-rolled strip when the ingots were soaked at 1200°C and 1150°C respectively for the TSCR process. And disperse and acicular precipitates were observed by TEM for air-cooling cast strips for process twin-rolling casting.

Abstract: The principle and method of analysis of the crystallographic planes standard equator plane projection are described in this article. Under different technological using similar Fe-3% Si silicon steel samples, conventional grain oriented silicon steel, 1150°C conventional hot-rolled grain oriented silicon steel and non-oriented silicon steel are obtained, respectively. Their pole figures of {200} planes for the samples are also obtained with XRD. The results state that the conventional Fe-3% Si grain oriented silicon steel has good Gauss texture, and 1150°C conventional hot-rolled grain oriented silicon steel has weak Gauss texture, meanwhile, non-oriented silicon steel has no Gauss texture, which prove the process has great the effect on the texture.

Abstract: The effect of hot rolling parameters including different hot rolling reduction, soaking time of ingots and chemical composition on cold rolling texture by TSCR process was studied. The result indicates that α fibers and γ fiber texture were affected by hot rolling reduction, and oriented density αfibers texture increases with hot rolling reduction rate increasing, and the texture components is same in the surface and different in the center. The strength of γ fiber texture, from {111}<110>to {111}<112>, is decreasing trendency for ingot soaked for 10min and 20min. however, changing trendency from {111}<110>to {111}<112> in 1/8 thickness and 1/4 thickness of cold rolling strip for ingot soaked for 30min. The volume fraction of {111}<112> is rising with the ingot soaked time and the maxium is 3.5 percent, and the volume fraction of {111}<112> is higher in every layer of cold rolling strip whose chemical composition includes Sn than without Sn, the volume fraction of {111}<112> is higher in 1/8 and 1/4 layers than the surface and center layers.

Abstract: The solidification characteristics of silicon steel in twin roll strip casting was studied by physical simulation. The experiments were designed to approximate the solidification conditions of twin roll strip casting. The strips with different cooling rate and different silicon content were prepared. The results show that the solidification structures of the strips with different cooling rate and different Si content are composed of columnar and equiaxed grains, and the solidification structures vary significantly. And with the decrease of cooling rate, the linear contraction rate decreases.

Abstract: The microstructure and textures of oriented silicon steel produced by Thin Slab Casting and Rolling (TSCR) were studied in laboratory. The fractions of equiaxed grains and columnar grains are close to 35% and 65% respectively in as-quenched ingot after being pulled out from the mould. The equiaxed grains and no texture gradient from surface to center can be observed for the 3-pass hot-rolled strips, and the inhomogeneities of microstructure and texture in thickness are relatively clear for the 7-pass samples. The subsurface texture of the hot-rolled sample contains of e (TD// <110>) fibers. The texture of the cold-rolled samples mainly consists of a (<110>//RD) and g (<111>//ND) fibers, and Goss texture ({110}<001>) disappears. The strong a fiber, weak g fiber and minor {001}<110>can be found in all layers in the cold-rolled condition.

Abstract: Hot deformation was applied on Fe-3%Si by the Gleeble-1500 thermo-mechanical system, and the effect of solute depleted area around the primary MnS particles precipitated prior to hot deformation on the distribution of strain-induced MnS particles was investigated. The obtained results showed that the depleted area around primary MnS particles affects significantly the distribution of strain-induced MnS particles, and the involved parameters were discussed.

Abstract: A new approach to obtain high strength of non-oriented electrical steel by addition of phosphorus is proposed. The method includes B-additions which suppress grain boundary P segregation, strengthen the grain boundary cohesion and enhance the P solid solution hardening. Two 3% Si steels, a B-free 0.1%P steel and a 20 ppm B-added 0.1%P steel were analyzed. The microstructures were studied by EBSD. The B-addition resulted in a pronounced rotated cube component, {100}<011>, after a hot-band annealing treatment. A -fiber texture was developed in the B-free steel. The B-addition caused a retardation of the recrystallization, allowing for the growth of grains with a lower stored energy, such as rotated cube oriented grains. The steels were further cold rolled and recrystallization annealed to observe a similar effect after large cold reductions. The present contribution focuses on the potential of this concept to obtain high strength 3% Si steels with low core losses.

Abstract: Powder metallurgy (PM) method to fabricate 6.5% silicon steel attracts much attention due to the lower energy consumption and cost. In this paper, Fe-6.5%Si alloy was prepared by spark plasma sintering (SPS) from the mixture of Fe and FeSi powders with different size. The sintering process was investigated through the shrinkage behavior, phase change and microstructure. The results show that the shrinkage starts from 500°C, lower than conventional sintering methods. The sintering temperature and FeSi powder size influence the reaction between Fe and FeSi.

Abstract: Research performed at Ghent University, regarding new production methods for electrical steel, has shown that high silicon steel suffers an ageing phenomenon at room temperature. Recent studies carried out by the same group using different analysis techniques (Mossbauer spectroscopy, neutron diffraction, etc) brought to light a probable process of ordering towards the D03-structure, which is responsible for the observed low ductility during cold rolling and makes the processing of steel extremely difficult. In addition, the Si-steels become more brittle as the delay time between hot and cold rolling is increased. Frequency dependent internal friction (FDIF) studies were performed on different Fe - Si alloys with a Si content varying from 3.73 at. % to 8.7 at. % immediately after several thermal treatments and compared with ultra-low carbon steel. The evolution of relaxation peaks during the IF measurements, performed at constant room temperature, helps to understand the ageing mechanisms. Three processes have been observed: firstly, as expected, addition of Si reduces the carbon Snoek peak. Secondly, a peak associated to C - Si is formed. Thirdly, a low frequency peak associated with Zener relaxation (Si atom pairs) appears for a content of approximately 3.77 wt. % Si. The two latter peaks decrease with ageing time and in the case of the Zener peak there is a notable displacement to higher frequencies with a small increase of the Si content. The reduction of the peaks during the ageing after annealing is more noticeable in quenched specimens than in air cooled ones, and in furnace cooled specimens the reduction is even smaller, indicating that the process is really an ageing phenomenon. Room temperature short-range ordering might explain both the lowering of the Zener peak and the observed macroscopic embrittlement.

Abstract: The effects of heating rate and annealing temperature on the microstructure and mechanical properties of cold rolled Al-Si, low C non-oriented electrical steels are investigated using SEM metallography and uniaxial tensile tests. The experimental results show that short term annealing at temperatures up to 850 °C result in microstructures consisting of recrystallized ferrite grains with sizes similar to those observed in industrial semi-processed strips subjected to long term batch annealing treatments. Within the temperature range investigated, the grain size increases and the 0.2% offset yield strength decreases with increasing temperature. It was observed that the rate of change of grain size with increasing temperature increases when annealing is performed at temperatures greater than Ac1 (~870 °C). This effect is attributed to Fe3C dissolution and rapid C segregation to austenite for annealing temperatures within the ferrite+austenite phase field. This leads to faster ferrite growth and formation of pearlite when the steel is finally cooled to room temperature. The presence of pearlite at room temperature decreases the ductility of samples annealed at T > Ac1.