A method for manufacturing oriented silicon steel without glass film and annealing separator

Abstract

The invention discloses a glass-film-free oriented silicon steel manufacture method. The method comprises the following steps of: (1) smelting; (2) hot rolling and normalizing; (3) cold rolling; (4) decarburization and nitriding, wherein a cold-rolled sheet is subjected to decarburization annealing treatment in wet N2+H2 protective gas at 800 to 860 DEG C, and oxidation energy is controlled within 0.16 to 0.40; carbon in the steel sheet can be reduced to below 30ppm by the decarburization annealing treatment while an oxide layer mainly containing SiO2 is formed on the surface of the steel sheet, and the single-side oxygen content of the steel sheet is controlled to below 0.7g / m<2>; and continuous nitriding treatment is carried out on the steel sheet in ammonia-contained N2+H2 protective gas with oxidation energy of 0.05 to 0.15 to control the nitrogen content of the steel sheet within 180ppm to 280ppm; (5) application of an isolation agent; (6) high-temperature annealing and temperature rising and maintenance, wherein the steel sheet is heated to 1150 to 1250 DEG C in dry N2+H2 mixed atmosphere containing 50% to 90% of N2 and H2, is maintained at the 1150 to 1250 DEG C in pure hydrogen atmosphere for above 15 hours; and (7) coating of an insulation coating, stretching, leveling and annealing, thus obtaining the grain-oriented silicon steel product with an excellent magnetic property.

Description

technical field [0001] The invention relates to a method for manufacturing oriented silicon steel, in particular to a method for manufacturing oriented silicon steel without a glass film and an annealing separator. Background technique [0002] In the production of grain oriented silicon steel, the steel plate needs to be in wet H 2 -N 2 Continuous decarburization annealing is carried out in a protective atmosphere. The purpose is to reduce the carbon in the steel plate to below 30ppm, so as to prevent the magnetic aging of the finished product. During the decarburization annealing process, the surface of the steel plate is formed with SiO 2 and Fe 2 SiO 4 The main oxide layer, during the secondary recrystallization annealing process, undergoes a solid-state diffusion reaction with the magnesium oxide coated on the surface of the steel plate: 2MgO+SiO 2 →Mg 2 SiO 4 , forming the bottom layer of magnesium silicate glass film. The bottom layer of magnesium silicate gl...

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Problems solved by technology

However, this method is often difficult to completely brush off the magnesium silicate on the surface to obtain a product with a smooth surface, and this method cannot completely eliminate the oxide inclusions near the surface of the steel plate

[0011] Japanese patent JP08269560A adds chloride to magnesia as an annealing separator. Adding a large amount of chloride will cause certain corrosion on the surface of the steel plate during the secondary recrystallization annealing process, affect the surface inhibitor, and cause secondary recrystallization to be unstable.

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