Method for producing oriented electrical steel with excellent surface quality

Abstract

The invention discloses a method for producing oriented electrical steel with excellent surface quality, and belongs to the technical field of oriented electrical steel production. The method comprises the following processes of: heating a casting blank at the temperature of between 1,000 and 1,190 DEG C, and then performing hot rolling; normalizing the hot rolled plate at the temperature of between 980 and 1,100 DEG C, and washing the plate by using acid; cold-rolling the plate to the thickness of a finished product under high rolling reduction rate of 86 to 93 percent; heating the cold rolled steel plate to the temperature of between 750 and 860 DEG C, and nitriding in ammonia-containing nitrogen and hydrogen mixed gas; performing decarburizing annealing at the temperature of between 800 and 860 DEG C; then coating a magnesium oxide isolation layer; raising the temperature to 1,200+ / -50 DEG C at the speed of 10 to 20 DEG C per hour in the nitrogen and hydrogen mixed gas, preserving the heat for 10 to 20 hours in hydrogen, and completing high-temperature annealing to obtain a finished product of secondary re-crystallization textures; and coating an insulating stress coating. The method has the advantage of producing the oriented electrical steel without defect on the surface and with strong adhesive force and uniform magnesium silicate bottom layer.

Description

technical field [0001] The invention relates to the technical field of oriented electrical steel, and in particular provides a production method of oriented electrical steel with excellent surface quality. Background technique [0002] Grain oriented electrical steel is a metal soft magnetic material with "Goss texture", that is, (110)<001> crystal texture, the silicon content is usually below 4.5%, and the thickness is 0.10-0.35mm. Grain-oriented electrical steel is mainly used as a core material for transformers due to its excellent magnetic properties along the rolling direction. The production method of grain-oriented electrical steel is proposed by N.P.Goss in U.S. Patent No. 1965559, which is produced by secondary cold rolling with intermediate annealing. The study found that the excellent magnetic energy source of grain-oriented electrical steel sheet is due to the "Goss texture" formed by secondary recrystallization during the final high-temperature annealing ...

AI Technical Summary

Problems solved by technology

Due to the high heating temperature, the following problems are brought about: (1) The surface layer of the slab melts into slag, which leads to an increase in manpower for the maintenance of the heating furnace; (2) Coarse grains are formed during the heating process, and the part with coarse grains cannot be secondary Recrystallization, resulting in linear crystals; (3) It is difficult to ensure that the slab is at an ideal temperature during the hot rolling process, which is easy to produce uneven inhibitors, which eventually leads to poor quality of secondary recrystallization; (4) due to the hot rolling process Large center edge cracks, low yield

The disadvantage of this method is that the oxide layer formed during the decarburization annealing process is destroyed in the later stage of nitriding, the bonding force with the steel strip substrate is weakened, it is difficult to form a good bottom layer, and the insulating coating on the surface of the final product is prone to dew crystals and other phenomena

[0006] To solve the above problems, it is necessary to strictly control the heating rate of decarburization annealing and the atmosphere in the furnace. At the same time, the atmosphere in the furnace must also be strictly controlled during the high-temperature annealing process. In this way, the production difficulty will increase and bring a lot of inconvenience to the production.