The changes of microstructure, phase and composition of 3 % grain oriented silicon steel after solid powder siliconizing and diffusion annealing as well as their effects on magnetic properties were studied. The results showed that wellstructured compound layer could be prepared on grain oriented silicon steel by infiltrating silicon at 950 ℃ for 6 minutes，and the surface phases were Fe3Si and FeSi. After diffusion annealing at 1 050 ℃ for 1 hour，annealed samples with good organization properties were obtained. When the annealing time was 2 hours, a homogenized sample with the mass fraction of silicon close to 6.5 % (6.43 %) was obtained，and the surface phase was the single αFe phase. After solid powder siliconizing and diffusion annealing，the medium and high frequency iron loss of the sample was significantly reduced by 50 %~86 %，and the iron loss reduction rate of the sample annealed for 1 hour was higher. After solid powder siliconizing and diffusion annealing，the magnetic induction intensity decreased slightly.

The causes of white stripe defects on the surface of grain oriented silicon steel were analyzed. The surface morphology was observed by threedimensional video microscope, the crosssection morphology of the steel and the surface morphology of the defect area after pickling were observed by field emission scanning electron microscope, and the energy spectrum composition was analyzed by energy spectrum analyzer. The analysis result showed that there was elliptical insulation layer falling off in the white stripe defect, and the magnesium silicate substrate in the defect area was abnormal, of which the thickness was much thicker than the normal area. It indicated that the white stripe defect area had been damaged before coating magnesium oxide. After pickling, the spicules with the main composition of O, Al and Si were found in the defect area of white stripe. It was found that the spicules originated from the refractory used in decarburization annealing furnace. The refractory fiber fell and adhered into the surface of the steel strip during decarburization annealing, and was pressed into the strip surface in the process of secondary rolling, which destroyed the oxide film, and affected the formation of the magnesium silicate substrate, and caused the white strip defect on the surface of the steel production after high temperature annealing. This kind of defect has been eliminated by improving the use method of insulating refractory fiber.

In viewing of the improving grading criteria of grain oriented silicon steel containing copper, through controlling the critical hot rolling process of the grain oriented silicon steel, and formulating the effective optimization mode of the velocity control of finish rolling, reducing the rolling time on finish rolling process and increasing the finishing temperature of finish rolling, the qualification rate of the degree of the grain oriented silicon steel containing copper was remarkably improved. The research results showed that more dispersed precipitates were produced in the containgcopper grain oriented silicon steel at higher finishing temperature, and the {110} surface texture in the quarter layer of hot rolled plate increased obviously. The productive practice proved that the effective optimization mode of the velocity control of finish rolling can evidently optimize the magnetic properties of the containingcopper grain oriented silicon steel.

The effects of coiling temperature on the microstructure and magnetic properties of 0.5 % Si nonoriented silicon steel were studied under industrial production. The results showed that when the coiling temperature increased from 600 ℃ to 700 ℃, the microstructure of the hotrolled steel was more uniform, the grain size of the hotrolled steel and the annealed steel was larger, and the favorable texture components was increased and the unfavorable texture components was decreased, which reduced the core loss and rose the magnetic induction of the annealed steel. When the coiling temperature was 700 ℃, the magnetic properties of the annealed steel were better, with the core loss P1.5/50 of 5.329 W/kg and the magnetic induction B50 of 1.762 T.

In order to improve the quality of non oriented electrical steel and reduce the production cost, the evolution law of inclusions, the changes of magnetic properties and surface quality of finished products in RH refining process under different molten steel circulation flow rates were analyzed. The results showed that the change of RH refining process had no obvious effect on the composition of inclusions in molten steel, the number of inclusions in hot rolled samples and the magnetic properties of finished products, but had a negative correlation effect on the surface quality. The larger the circulating flow rate of molten steel was, the lower the inclusion degradation rate was. The equivalent area of inclusions in molten steel, especially the larger inclusions above 5 μm, was negatively related to the circulating flow rate of molten steel. The inclusions (including the second phase precipitates) in hot rolled samples were mainly the second phase precipitates AlN and MnS, and a small amount of oxide inclusions. The amount of inclusions had no correlation with RH refining process. On the premise of ensuring the quality to meet the requirements, the circulation flow of molten steel in RH process can be adjusted appropriately to reduce the production cost.

Calcium aluminate desulphurization flux for RH process was designed to avoid the corrosion and storage problem of CaO-CaF2 flux. The Al2O3 content was set a range of 33 %-37 % in accordance with slagsteel sulphur ratio and melting time, the residual slag inside chamber was also taken into consideration. The optimized range of particle size was between 3-5 mm. The flux was put into production trials and the result was evaluated. It was concluded that the desulphurizing effect had a strong correlation with initial sulphur content and volume of flux addition. The regression analysis showed that deep desulphurization is easier to be achieved if the initial sulphur content is lower than 30×10^-6, or it will be much harder on the contrary.  Compared to  CaO-CaF2 flux, the alloy yield has been improved when using calcium aluminate desulphurization flux. 

Modern measurement technology and digital management means were used to realize realtime monitoring, recording and abnormal alarm of tension sensor measurement signal. At the same time, modern signal processing and analysis methods were adopted, and empirical mode decomposition （EMD) algorithm was proposed to decompose the tension signal, which can extract and analyze the fault characteristics of the tension sensor online and in real time, and carry out closedloop control. It creates great benefits for detecting and diagnosing the early fault of the sensor and optimizing the quality of electrical steel products.

The restrict segment existed in CSP soaking furnace were analyzed while CSP plant enhancing the circulate productivity in the soaking furnace.Then the measures to raise the circulate productivity of the CSP soaking furnace were put forward from the respect of reducing the heating time, enhancing the heating efficiency and fasting roller cleaning.