Preparation method of oriented high silicon steel

A preparation method of oriented high silicon steel, being performed according to the following steps of:

• (1) smelting to obtain molten steel according to set components in percentage by weight:
• 0.001-0.003% of C, 5.0-6.6% of Si, 0.2-0.3% of Mn, 0.05-0.12% of Al, 0.01-0.04% of V, 0.03-0.06% of Nb, 0.02-0.03% of S, 0.009-0.020% of N, O which is less than or equal to 0.0020%, and the balance being Fe and unavoidable impurities;
• (2) performing a thin-strip casting course:
• enabling the molten steel to be charged from a gate into a tundish which is preheated at the temperature of 1200-1250 DEG C., controlling the superheat temperature to be at 20-50 DEG C., and through the tundish, enabling the molten steel to enter a thin-strip casting machine and to be formed into cast strips of which the thickness is 1.8-3.0 mm;
• (3) after drawing out cast strips, cooling the cast strips to 1000-1050 DEG C. at the cooling rate of 50-100 DEG C./s under inert atmosphere conditions, then performing hot rolling, wherein the primary rolling temperature is 1000-1050 DEG C., the final rolling temperature is 900-980 DEG C., and the rolling reduction is 10-15%, and forming hot-rolled cast strips;
• (4) cooling the hot-rolled cast strips to 550-600 DEG C. at the cooling rate of 20-30 DEG C./s, coiling the cooled cast strips, then performing hot rolling/warm rolling on the coiled cast strips at low temperature under a nitrogen atmosphere condition, wherein the primary rolling temperature is 755-765 DEG C., the final rolling temperature is 550-600 DEG C., and the total rolling reduction is 70-80%, and forming warm-rolled strips;
• (5) removing oxidized scales of the warm-rolled strips through pickling, and then performing cold rolling for multiple times at 100-200 DEG C., wherein the total rolling reduction is 60-80%;
• during the cold rolling course, performing aging treatment twice to 3 times, wherein the aging treatment temperature is 280-320 DEG C., and the duration is 240-300s, and performing the aging treatment each time between two adjacent cold rollings, so as to obtain cold rolled strips;
• (6) performing recrystallization annealing on the cold rolled strips at 840-860 DEG C. for 120-180s under the condition of nitrogen-hydrogen mixed atmosphere, wherein the dew point of the mixed atmosphere is controlled at 30-60 DEG C., then coating with an MgO layer, and finally coiling so as to obtain coated cold-rolled strips;
• (7) putting the coated cold-rolled strips into a ring furnace at 390-410 DEG C., under the hydrogen circulation condition, firstly heating the coated cold-rolled strips to 990-1010 DEG C. at the rate of 30-40 DEG C./h, then heating the heated coated cold-rolled strips to 1120-1140 DEG C. at the rate of 10-20 DEG C./h, then heating the heated coated cold-rolled strips to 1220-1240 DEG C. at the rate of 30-40 DEG C./h, and keeping the temperature for 20-30 h for purification annealing;
• and
• (8) performing surface cleaning on the coated cold-rolled strips after purification annealing so as to remove the oxidized scales, then coating with an insulating layer, performing flat stretch annealing at 790-810 DEG C., finally performing air-cooling to be at 650 DEG C. or below and coiling so as to obtain the oriented high silicon steel.