Method for manufacturing grain-oriented silicon steel with single cold rolling

A method for producing grain-oriented silicon steel with single cold rolling, comprising:

• 1) smelting:
• after secondary refining and continuous casting of molten steel in a converter or an electric furnace, a casting blank having the following composition based on mass is obtained:
• C 0.035-0.065%, Si 2.9-4.0%, Mn 0.08-0.18%, S 0.005-0.012%, Als 0.015-0.035%, N 0.0050-0.0130%, Sn 0.001-0.15%, P 0.010-0.030%, Cu 0.05-0.60%, Cr≦0.2%, balanced by Fe and unavailable inclusions;
• 2) hot rolling:
• the casting blank is heated to 1090-1200° C. in a heating furnace, rolling begins at a temperature below 1180° C. and ends at a temperature above 860° C., and a hot rolled steel sheet of 1.5-3.5 mm is thus obtained and then coiled at 500-650° C.;
• 3) normalization:
• normalizing annealing is carried out at 1050-1180° C. (1-20 s)+850-950° C. (30-200 s), and cooling is carried out at 10° C./s-60° C./s;
• 4) cold rolling:
• the steel sheet is rolled to a thickness of a final product with single cold rolling at a cold rolling reduction rate of 75-92%;
• 5) decarburization:
• the steel sheet rolled to the thickness of the final product is decarburizing annealed at 780-880° C. for 80-350 s in a protective mixed gas atmosphere of H2 and N2 comprising 15-85% H2, a dew point of the protective mixed gas atmosphere is 40-80° C., a total oxygen [O] in a surface of the decarburized steel sheet is 171/t≦[O]≦313/t (t represents an actual thickness of the steel sheet in mm), an amount of absorbed nitrogen is 2-10 ppm, then the sheet is coated with a high-temperature annealing separator comprising MgO as a main component;
• 6) high-temperature annealing:
• a protective annealing atmosphere below 1000° C. is comprised of a mixed gas of H2 and N2 or pure N2 and has a dew point of 0-50° C., a temperature holding time at a first stage is 6-30 h, an amount of absorbed nitrogen during high-temperature annealing is 10-40 ppm;
• and
• 7) hot leveling annealing:
• a conventional hot leveling process is carried out,
• wherein at ¼-⅓ and ⅔-¾ of the thickness of the normalized steel sheet, a ratio of Gaussian texture (110)[001] to cubic texture (001)[110] is controlled to be 0.2≦I(110)[001]/I(001)[110]≦8, wherein I(110)[001] and I(001)[110] are intensities of Gaussian and cubic texture respectively.