The production of thin gauge grain oriented silicon steel of 0.20 mm or below is rather difficult due to strong surface effects and shows high tendency of degraded or even waste products. Because the techniques for producing such high end products are of high business secrets for enterprises and rather limited reports are found in literatures and, in addition, different composition designs of various enterprises show the suitable processing parameters and the relationship of average grain sizes, textures and inhibitors of their own, each enterprise should seek and find out suitable parameters in its own products. This paper examined in laboratory, based on a successfully produced 0.20 mm thick thin gauge grain oriented silicon steel in the production lines, its repeatability and structural susceptibility and revealed the features of grain size distributions, inhibitors and textures of both matrix grains and secondary recrystallized grains in annealed sheets from primary recrystallization to secondary recrystallization stages. It is hoped to clarify theoretically the significant surface effects brought by thinning sheet thickness and find out key structural and textural parameters and to lay out a better fundamental of comprehensive control of thin gauge grain oriented silicon steel production in our country as a whole. Results show that good repeatability of secondary recrystallization is confirmed. The average primary grain size is about 18 μm and secondary recrystallization temperature is 1 050 ℃ with a finishing temperature of less than 15 ℃. The average grain size before the start of secondary recrystallization increased less than 1SymbolmA@m in comparison with that of primary recrystallization.


The microstructure characteristics, the effects of cold rolling reduction and hightemperature annealing atmosphere on magnetic properties were researched in this paper, in order to develop the 0.20 mm thin gauge grainoriented silicon steel with qualified magnetic properties. The results showed that: the secondary recrystallization of the obtained 0.20 mm thin gauge grainoriented silicon steel was complete, and magnetic properties of the iron loss P1.7/50  and the magnetic induction J800  were 0.89 W/kg and 1.906 T respectively; and the surface textures of the hot rolled and normalized samples were mainly Goss textures, with the cold rolled texture mainly {001}〈110〉 and the annealed texture mainly {411}〈148〉, and the decarburized grain size was about 21.17 μm with very few Goss grain; and the suitable cold rolling reduction of the researched steel was 91.3 %, and the suitable atmosphere for high temperature annealing was 75 % N2.

The evolution of microstructure and texture of grainoriented silicon steel with low temperature reheating in experiment had been studied by OM, EBSD and XRD. The experimental results showed that there was an alternating banded structure in which ferrite layers and pearlite layers alternated with each other in hot rolled slab, and the microstructure was inhomogeneous along the thickness direction. The {001}〈110〉, {112}〈110〉 texture and {110}〈001〉 texture in the hotrolled sheet were also inhomogeneous along the thickness direction. After cold rolling, the ferrite grains were severely elongated, forming a fibrous structure elongated along the rolling direction. The texture types of coldrolled sheet were mainly α texture and γ texture; The matrix recoverd and recrystallized during decarburization, the microstructure was a single ferrite equiaxed grain, and the texture was mainly γ texture; After nitriding, the texture of secondary coldrolled sheet only decreased in strength, and the change of texture type was not obvious. The secondary recrystallization developed perfect, and the grain size was about 10-20 mm. The texture type was sharp Goss texture. And the magnetic induction B800 was 1.926 T and the iron loss P1.7/50 was 1.047 W/kg.

The role of grainoriented silicon steel in the energy and power industry chain,and the important value in the carbon peak and and carbon neutralization strategy were introduced in this paper,and the double opportunities of market scale and structure promotion for grainoriented silicon steel brought by the carbon peak and carbon neutralization strategy and especially the national energy reform during the 14th Five Year Plan period were analyzed.Meanwhile,it is also analyzed that how steel plants and transformer plants can achieve winwin development benefits through highgrade grainoriented silicon steel under the new energy efficiency standard system.

Different normalization annealing experiments were carried out on 27AHSW450 highstrength nonoriented silicon steel. The results showed that equiaxed crystals with almost complete recovery and recrystallization were observed at above 950℃ after normalized at 900~1030 ℃ for 50 minutes. The distribution of texture transferred from hotrolled sheet texture to randomly oriented texture. After final annealing at 950 ℃ for 6 minutes, the texture distribution in the final annealing sheet tended to be consistent, mainly consisting of λ fibre texture, α* fibre texture and strong γ fibre texture. The magnetic induction of rolling direction was better than that of transverse direction. The highest magnetic induction value was 1.64 T when normalized at 900 ℃. The core loss differed a little in rolling direction and transverse direction. The lowest iron loss value was 25.1 W/kg when normalized at 950 ℃.

Epstein frame samples of the silicon steel of 35SW440 were produced by two stress relieving annealing processes of continuous annealing and well annealing. The comparative investigations were conducted on the relationships between the two stress relieving annealing process and their microstructures, precipitation and magnetic properties. The results showed that after stress relief annealing, the iron loss reduced and the magnetic induction improved. Compared with the well type annealing process, the iron core of the steel produced by continuous annealing process had poor magnetic properties under the condition of high magnetic density due to the obvious surface nitriding phenomenon on the surface of the steel. The surface nitriding was due to the unreasonable design of the protective atmosphere and annealing process, resulting in a large number of fine and dispersed AlN precipitates produced in steel. AlN precipitates affected the movement of domain wall and magnetic moment, resulting in the deterioration of magnetic properties. By contrast, the well annealing process reduced the iron loss of the electrical steel sheet under high magnetic density, and improved properties index of iron core due to the effective control of the surface nitriding in steel.


According to the development trend of domestic nonoriented silicon steel in recent ten years and the future development prospect of downstream industry, the demand of domestic nonoriented silicon steel in the next 15 years is predicted. It is estimated that by 2025, 2030 and 2035, the annual demand of nonoriented silicon steel in China will be 11.25 million tons, 13 million tons and 15 million tons respectively. Among them, the proportion of medium and high grade brands should be increased from 20% to 30%, 40% and 50% respectively. It is the general trend to focus on the development of medium and high grade nonoriented silicon steel. However, in the future, medium and high grade nonoriented silicon steel will face fierce market competition, so we should improve the market competitiveness from two aspects of product quality and cost control.

Calcium aluminate flux is applied to RH desulphurization process protecting the refractories due to Fluoride free and easy storage condition request. In order to pursuit better effect of desulphurization,a new desulphurization model was constructed in this paper. The model was established and proved as the correlation coefficient equals 0.99. The values of the parameters could be got from the practice data of RH desulphurization. It could be concluded from the model that the process is decided by the effective time of desulphurization, which means terminal time of desulphurization minus the time reaching the critical liquid slag volume. The worst situation is when the melting speed of flux is too low to reaching the critical liquid slag volume, no desulphurization happens. For further steps, the model was used to simulate the operation optimization, which revealed that doubleaddition is better than single addition when the total volume of flux equals, but that doesn’t mean the more times of addition are better, however, the best addition times could be calculated by the model.