METHOD FOR PREPARING BOTTOM-LAYER-FREE ORIENTED SILICON STEEL AND PRODUCT OBTAINED THEREBY

The present invention belongs to the technical field of the preparation of silicon steels, and particularly relates to a method for preparing a bottom-layer-free oriented silicon steel. During decarburization annealing, the thickness of an oxide film on the surface layer of a strip steel is 1.5-2.5 μm, and the atomic weight ratio of the element Si to the element Fe in the oxide film satisfies Si/(Si+Fe)â¿¥0.76. During high-temperature annealing, a cooling stage sequentially comprises: when the temperature ranges from 1200ºC to 500ºC, cooling in a cover, wherein a protective gas is a mixed gas containing nitrogen and hydrogen, and the volume percentage of hydrogen in the mixed gas is greater than 3%; when the temperature ranges from 500ºC to 200ºC, cooling in the cover, wherein the protective gas is nitrogen; and when the temperature is lower than 200ºC, opening an inner cover for air cooling. In the method for preparing a bottom-layer-free oriented silicon steel according to an embodiment of the present disclosure, by controlling the thickness of an oxide film during the decarburization annealing stage of a strip steel and by means of certain processes, such as a cooling stage during high-temperature annealing, the bottom-layer-free oriented silicon steel, which is good in surface smoothness, good in surface homogenization, high in yield and excellent in magnetic performance, is obtained. La presente invención pertenece al campo técnico de la preparación de aceros al silicio, y particularmente a un método de preparación de acero al silicio de grano orientado sin vidrio. Durante un recocido de descarburación, el grosor de una película de óxido sobre una superficie de la tira es de 1.5-2.5 µm; una relación de peso atómico del elemento Si y el elemento Fe en la película de óxido satisface: Si/(Si+Fe) = 0.76; durante un recocido a alta temperatura, una etapa de enfriamiento incluye secuencialmente: enfriar con un recubrimiento interior cuando la temperatura desciende de 1200 °C a 500 °C; en donde un gas protector es un gas mixto que contiene nitrógeno e hidrógeno, y un porcentaje en volumen del hidrógeno en el gas mixto es >3 %; enfriar con el recubrimiento interior cuando la temperatura desciende de 500 °C a 200 °C; en donde el gas protector es nitrógeno; y enfriar al aire al retirar el recubrimiento interior cuando la temperatura es < 200 °C.