Preparation method of oriented high silicon steel

Abstract

The preparation method includes steps of (1) melting steel according to in weight percentage 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) forming cast strips after a thin-strip casting course; (3) hot-rolling the cast strips under inert atmosphere conditions; (4) cooling the hot-rolled cast strips to 550-600 DEG C., coiling and performing low-temperature hot rolling/warm rolling on the coiled cast strips under a nitrogen atmosphere condition; (5) removing oxidized scales though pickling, performing cold rolling multiple times; (6) performing recrystallization annealing, coating with an MgO layer, and coiling; (7) performing purification annealing under hydrogen circulation conditions; and (8) removing oxidized scales, coating with an insulating layer, performing flat stretch annealing, and air-cooled coiling.

Claims

1. 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.

2. The preparation method of oriented high silicon steel of claim 1, wherein the thickness of the oriented high silicon steel is 0.10-0.25 mm.

3. The preparation method of oriented high silicon steel of claim 1, wherein the oriented high silicon steel has the following magnetic properties: P.sub.10/50 at 0.18-0.62 W/kg, P.sub.10/400 at 6.75-9.5 W/kg, magnetic induction B.sub.8 at 1.74-1.81 T, and B.sub.8/B.sub.S=0.9610.978.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of a preparation method of oriented high silicon steel disclosed by the present invention;

(2) FIG. 2 is a microstructure micrograph of the product in Embodiment 3 disclosed by the present invention;

(3) FIG. 3 is a macrostructure chart of the cold-rolled strips after recrystallization annealing in Embodiment 3 disclosed by the present invention; and

(4) FIG. 4 is a microstructure micrograph of the cast strips in Embodiment 3 disclosed by the present invention; precipitation of MnS particles with the size of 20-200 nm is shown in the figure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(5) The thin strip caster adopted in Embodiments disclosed by the present invention is that disclosed in Chinese Patent publication No. CN103551532A.

(6) The preparation method of oriented high silicon steel in embodiments disclosed by the present invention based on a thin strip casting technique is shown in FIG. 1: molten steel smelted from a ladle is poured into a tundish, and flows into a thin strip caster from a feeding nozzle, so that a molten pool is formed in the crystallizer formed by two rotating casting rolls and side block panels and the molten steel is solidified to form cast strips; after hot rolling for one time, the cast strips are coiled; low temperature hot and warm rolling are performed on the hot-rolled strips in a protective atmosphere, and then pickling cold rolling is performed; after completion of cold rolling, primary recrystallization annealing and MgO coating are performed, and then the high temperature annealing course is performed; after high temperature annealing, steel coils are coated with an insulation layer, the coated steel coils are stretched flat, and then the flat steel coils are coiled once more.

(7) A Zeiss Ultra 55 scanning electron microscope is used for observing the microstructure in the embodiments disclosed by the present invention.

(8) The purity of hydrogen adopted in the embodiments disclosed by the present invention is 99.9%.

(9) The purity of nitrogen adopted in the embodiments disclosed by the present invention is 99.9%.

Embodiment 1

(10) Smelting to obtain molten steel according to set components in percentage by weight: 0.001% of C, 6.6% of Si, 0.2% of Mn, 0.12% of Al, 0.01% of V, 0.06% of Nb, 0.02% of S, 0.020% of N, 0.0016% of O, and the balance being Fe and unavoidable impurities;

(11) 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 DEG C., controlling the superheat temperature to be at 20 DEG C., and through the tundish, enabling the molten steel to enter a thin strip caster, to form a molten pool in the crystallizer formed by rotating casting rolls and side block panels, and to be solidified and formed, wherein the thickness is 2.0 mm;

(12) after drawing out cast strips, cooling the cast strips to 1000 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 DEG C., the final rolling temperature is 900 DEG C., and the rolling reduction is 15%, and forming hot-rolled cast strips;

(13) cooling the hot-rolled cast strips to 580 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 580 DEG C., and the total rolling reduction is 70%, and forming warm-rolled strips;

(14) removing oxidized scales of the warm-rolled strips through pickling, and then performing cold rolling 6 times at 100-200 DEG C., wherein the total rolling reduction is 80%; during the cold rolling course, performing aging treatment 2 times, wherein the aging treatment temperature is 280 DEG C., and the duration is 300 s, and performing aging treatment each time between two adjacent cold rollings, so as to obtain cold rolled strips with the thickness of 0.10 mm;

(15) performing recrystallization annealing on the cold rolled strips at 840-860 DEG C. for 120 s under the condition of nitrogen-hydrogen mixed atmosphere, wherein the dew point of the mixed atmosphere is controlled to be at 30 DEG C.; then coating with an MgO layer, and finally coiling so as to obtain coated cold-rolled strips, wherein the volume concentration of the hydrogen in the mixed atmosphere of nitrogen and hydrogen is 30%;

(16) 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, 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 1240 DEG C. at the rate of 30-40 DEG C./h, and keeping the temperature for 20 h for purification annealing; and

(17) 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., and finally performing air-cooling to be at 650 DEG C. or below and coiling so as to obtain the oriented high silicon steel with magnetic properties: P.sub.10/50 at 0.18 W/kg, P.sub.10/400 at 6.75 W/kg, magnetic induction B.sub.8 at 1.74 T, and B.sub.8/B.sub.S=0.961.

Embodiment 2

(18) Smelting to obtain molten steel according to set components in percentage by weight: 0.003% of C, 5.0% of Si, 0.3% of Mn, 0.05% of Al, 0.04% of V, 0.03% of Nb, 0.03% of S, 0.009% of N, 0.0018% of O, and the balance being Fe and unavoidable impurities;

(19) 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 1250 DEG C., controlling the superheat temperature to be 50 DEG C., and through the tundish, enabling the molten steel to enter a thin strip caster, to form a molten pool in the crystallizer formed by rotating casting rolls and side block panels, and to be solidified and formed, wherein the thickness is 2.3 mm;

(20) after drawing out cast strips, cooling the cast strips to 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 1050 DEG C., the final rolling temperature is 980 DEG C., and the rolling reduction is 10%, and forming hot-rolled cast strips;

(21) cooling the hot-rolled cast strips to 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 600 DEG C., and the total rolling reduction is 70%, and forming warm-rolled strips;

(22) removing oxidized scales of the warm-rolled strips through pickling, and then performing cold rolling 7 times at 100-200 DEG C., wherein the total rolling reduction is 60%; during the cold rolling course, performing aging treatment 3 times, wherein the aging treatment temperature is 320 DEG C., and the duration is 240 s, and performing aging treatment each time between two adjacent cold rollings, so as to obtain cold rolled strips of which the thickness is 0.25 mm;

(23) performing recrystallization annealing on the cold rolled strips at 840-860 DEG C. for 180 s under the condition of nitrogen-hydrogen mixed atmosphere, wherein the dew point of the mixed atmosphere is controlled to be at 40 DEG C.; then coating with an MgO layer, and finally coiling so as to obtain coated cold-rolled strips, wherein the volume concentration of the hydrogen in the mixed atmosphere of nitrogen and hydrogen is 30%;

(24) 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, 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 DEG C. at the rate of 30-40 DEG C./h, and keeping the temperature for 30 h for purification annealing; and

(25) 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., and finally performing air-cooling to be at 650 DEG C. or below and coiling so as to obtain the oriented high silicon steel with magnetic properties: P.sub.10/50 at 0.62 W/kg, P.sub.10/400 at 9.5 W/kg, magnetic induction B.sub.8 at 1.81 T, and B.sub.8/B.sub.S=0.978.

Embodiment 3

(26) Smelting to obtain molten steel according to set components in percentage by weight: 0.002% of C, 6.5% of Si, 0.23% of Mn, 0.08% of Al, 0.02% of V, 0.05% of Nb, 0.026% of S, 0.018% of N, 0.0011% of O, and the balance being Fe and unavoidable impurities;

(27) 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 1210 DEG C., controlling the superheat temperature to be at 30 DEG C., and through the tundish, enabling the molten steel to enter a thin strip caster, to form a molten pool in the crystallizer formed by rotating casting rolls and side block panels, and to be solidified and formed, wherein the thickness is 1.8 mm;

(28) after drawing out cast strips, cooling the cast strips to 1030 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 1030 DEG C., the final rolling temperature is 940 DEG C., and the rolling reduction is 13%, and forming hot-rolled cast strips;

(29) cooling the hot-rolled cast strips to 550 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 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 DEG C., and the total rolling reduction is 70%, and forming warm-rolled strips;

(30) removing oxidized scales of the warm-rolled strips through pickling, and then performing cold rolling 5 times at 100-200 DEG C., wherein the total rolling reduction is 62%; during the cold rolling course, performing aging treatment 2 times, wherein the aging treatment temperature is 320 DEG C., and the duration is 240 s, and performing aging treatment each time between two adjacent cold rollings, so as to obtain cold rolled strips of which the thickness is 0.18 mm;

(31) performing recrystallization annealing on the cold rolled strips at 840-860 DEG C. for 160 s under the condition of nitrogen-hydrogen mixed atmosphere, wherein the dew point of the mixed atmosphere is controlled to be at 50 DEG C.; then coating with an MgO layer, and finally coiling so as to obtain coated cold-rolled strips, wherein the volume concentration of the hydrogen in the mixed atmosphere of nitrogen and hydrogen is 30%;

(32) 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 1230 DEG C. at the rate of 30-40 DEG C./h, and keeping the temperature for 24 h for purification annealing; and

(33) 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., and finally performing air-cooling to be at 650 DEG C. or below and coiling so as to obtain the oriented high silicon steel with magnetic properties: P.sub.10/50 at 0.22 W/kg, P.sub.10/400 at 7.1 W/kg, magnetic induction B.sub.8 at 1.76 T, and B.sub.8/B.sub.S=0.966.

Embodiment 4

(34) Smelting to obtain molten steel according to set components in percentage by weight: 0.001% of C, 5.8% of Si, 0.29% of Mn, 0.10% of Al, 0.03% of V, 0.06% of Nb, 0.02% of S, 0.015% of N, 0.0017% of O, and the balance being Fe and unavoidable impurities;

(35) 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 1220 DEG C., controlling the superheat temperature to be at 40 DEG C., and through the tundish, enabling the molten steel to enter a thin strip caster, to form a molten pool in the crystallizer formed by rotating casting rolls and side block panels, and to be solidified and formed, wherein the thickness is 3.0 mm;

(36) after drawing out cast strips, cooling the cast strips to 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 1050 DEG C., the final rolling temperature is 980 DEG C., and the rolling reduction is 15%, and forming hot-rolled cast strips;

(37) cooling the hot-rolled cast strips to 570 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 570 DEG C., and the total rolling reduction is 80%, and forming warm-rolled strips;

(38) removing oxidized scales of the warm-rolled strips through pickling, and then performing cold rolling 6 times at 100-200 DEG C., wherein the total rolling reduction is 70%; during the cold rolling course, performing aging treatment 3 times, wherein the aging treatment temperature is 280 DEG C., and the duration is 300 s, and performing aging treatment each time between two adjacent cold rollings, so as to obtain cold rolled strips with the thickness of 0.15 mm;

(39) performing recrystallization annealing on the cold rolled strips at 840-860 DEG C. for 140 s under the condition of nitrogen-hydrogen mixed atmosphere, wherein the dew point of the mixed atmosphere is controlled to be at 60 DEG C.; then coating with an MgO layer, and finally coiling so as to obtain coated cold-rolled strips, wherein the volume concentration of the hydrogen in the mixed atmosphere of nitrogen and hydrogen is 30%;

(40) 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, 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 1240 DEG C. at the rate of 30-40 DEG C./h, and keeping the temperature for 20 h for purification annealing; and

(41) 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., and finally performing air-cooling to be at 650 DEG C. or below and coiling so as to obtain the oriented high silicon steel with magnetic properties: P.sub.10150 at 0.34 W/kg, P.sub.10/400 at 7.4 W/kg, magnetic induction B.sub.8 at 1.77 T, and B.sub.8/B.sub.S=0.975.

Embodiment 5

(42) Smelting to obtain molten steel according to set components in percentage by weight: 0.003% of C, 5.2% of Si, 0.27% of Mn, 0.06% of Al, 0.04% of V, 0.04% of Nb, 0.028% of S, 0.014% of N, 0.0018% of O, and the balance being Fe and unavoidable impurities;

(43) 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 1230 DEG C., controlling the superheat temperature to be at 40 DEG C., and through the tundish, enabling the molten steel to enter a thin strip caster, to form a molten pool in the crystallizer formed by rotating casting rolls and side block panels, and to be solidified and formed, wherein the thickness is 2.5 mm;

(44) after drawing out cast strips, cooling the cast strips to 1000 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 DEG C., the final rolling temperature is 900 DEG C., and the rolling reduction is 12%, and forming hot-rolled cast strips;

(45) cooling the hot-rolled cast strips to 580 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 580 DEG C., and the total rolling reduction is 75%, and forming warm-rolled strips;

(46) removing oxidized scales of the warm-rolled strips through pickling, and then performing cold rolling 7 times at 100-200 DEG C., wherein the total rolling reduction is 67%; during the cold rolling course, performing aging treatment 2 times, wherein the aging treatment temperature is 300 DEG C., and the duration is 280 s, and performing aging treatment each time between two adjacent cold rollings, so as to obtain cold rolled strips of which the thickness is 0.18 mm;

(47) performing recrystallization annealing on the cold rolled strips at 840-860 DEG C. for 180 s under the condition of nitrogen-hydrogen mixed atmosphere, wherein the dew point of the mixed atmosphere is controlled to be at 30 DEG C.; then coating with an MgO layer, and finally coiling so as to obtain coated cold-rolled strips, wherein the volume concentration of the hydrogen in the mixed atmosphere of nitrogen and hydrogen is 30%;

(48) 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, 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 DEG C. at the rate of 30-40 DEG C./h, and keeping the temperature for 30 h for purification annealing; and

(49) 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., and finally performing air-cooling to be at 650 DEG C. or below and coiling so as to obtain the oriented high silicon steel with magnetic properties: P.sub.10/50 at 0.43 W/kg, P.sub.10/400 at 8.2 W/kg, magnetic induction B.sub.8 at 1.76 T, and B.sub.8/B.sub.S=0.965.

Embodiment 6

(50) Smelting to obtain molten steel according to set components in percentage by weight: 0.002% of C, 6.1% of Si, 0.3% of Mn, 0.07% of Al, 0.01% of V, 0.05% of Nb, 0.02% of S, 0.020% of N, 0.0012% of O, and the balance being Fe and unavoidable impurities;

(51) performing a thin strip casting course: enabling the molten steel to be charged through a gate into a tundish which is preheated at temperature of 1250 DEG C., controlling the superheat temperature to be at 50 DEG C., and through the tundish, enabling the molten steel to enter a thin strip caster, to form a molten pool in the crystallizer formed by rotating casting rolls and side block panels, and to be solidified and formed, wherein the thickness is 2.8 mm;

(52) after drawing out cast strips, cooling the cast strips to 1030 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 1030 DEG C., the final rolling temperature is 940 DEG C., and the rolling reduction is 15%, and forming hot-rolled cast strips;

(53) cooling the hot-rolled cast strips to 560 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 560 DEG C., and the total rolling reduction is 75%, and forming warm-rolled strips;

(54) removing oxidized scales of the warm-rolled strips through pickling, and then performing cold rolling 5 times at 100-200 DEG C., wherein the total rolling reduction is 80%; during the cold rolling course, performing aging treatment 3 times, wherein the aging treatment temperature is 300 DEG C., and the duration is 300 s, and performing aging treatment each time between two adjacent cold rollings, so as to obtain cold rolled strips of which the thickness is 0.12 mm;

(55) performing recrystallization annealing on the cold rolled strips at 840-860 DEG C. for 160 s under the condition of nitrogen-hydrogen mixed atmosphere, wherein the dew point of the mixed atmosphere is controlled to be at 40 DEG C.; then coating with an MgO layer, and finally coiling so as to obtain coated cold-rolled strips, wherein the volume concentration of the hydrogen in the mixed atmosphere of nitrogen and hydrogen is 30%;

(56) 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 1230 DEG C. at the rate of 30-40 DEG C./h, and keeping the temperature for 24 h for purification annealing; and

(57) 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., and finally performing air-cooling to be at 650 DEG C. or below and coiling so as to obtain the oriented high silicon steel with magnetic properties: P.sub.10/50 at 0.29 W/kg, P.sub.10/400 at 7.5 W/kg, magnetic induction B.sub.8 at 1.74 T, and B.sub.8/B.sub.S=0.973.

Embodiment 7

(58) Smelting to obtain molten steel according to set components in percentage by weight: 0.001% of C, 5.5% of Si, 0.22% of Mn, 0.11% of Al, 0.02% of V, 0.05% of Nb, 0.03% of S, 0.010% of N, 0.0018% of O, and the balance being Fe and unavoidable impurities;

(59) performing a thin strip casting course: enabling the molten steel to be charged through a gate into a tundish which is preheated at the temperature of 1200 DEG C., controlling the superheat temperature to be at 20 DEG C., and through the tundish, enabling the molten steel to enter a thin strip caster, to form a molten pool in the crystallizer formed by rotating casting rolls and side block panels, and to be solidified and formed, wherein the thickness is 3.0 mm;

(60) after drawing out cast strips, cooling the cast strips to 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 1050 DEG C., the final rolling temperature is 980 DEG C., and the rolling reduction is 15%, and forming hot-rolled cast strips;

(61) cooling the hot-rolled cast strips to 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 600 DEG C., and the total rolling reduction is 70%, and forming warm-rolled strips;

(62) removing oxidized scales of the warm-rolled strips through pickling, and then performing cold rolling 6 times at 100-200 DEG C., wherein the total rolling reduction is 76%; during the cold rolling course, performing aging treatment 2 times, wherein the aging treatment temperature is 280 DEG C., and the duration is 280 s, and performing aging treatment each time between two adjacent cold rollings, so as to obtain cold rolled strips of which the thickness is 0.18 mm;

(63) performing recrystallization annealing on the cold rolled strips at 840-860 DEG C. for 140 s under the condition of nitrogen-hydrogen mixed atmosphere, wherein the dew point of the mixed atmosphere is controlled to be at 50 DEG C.; then coating with an MgO layer, and finally coiling so as to obtain coated cold-rolled strips, wherein the volume concentration of the hydrogen in the mixed atmosphere of nitrogen and hydrogen is 30%;

(64) 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, 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 1240 DEG C. at the rate of 30-40 DEG C./h, and keeping the temperature for 20 h for purification annealing; and

(65) 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., and finally performing air-cooling to be at 650 DEG C. or below and coiling so as to obtain the oriented high silicon steel with magnetic properties: P.sub.10/50 at 0.49 W/kg, P.sub.10/400 at 7.8 W/kg, magnetic induction B.sub.8 at 1.77 T, and B.sub.8/B.sub.S=0.968.

Embodiment 8

(66) Smelting to obtain molten steel according to set components in percentage by weight: 0.003% of C, 5.8% of Si, 0.29% of Mn, 0.06% of Al, 0.03% of V, 0.05% of Nb, 0.021% of S, 0.017% of N, 0.0016% of O, and the balance being Fe and unavoidable impurities;

(67) 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 1220 DEG C., controlling the superheat temperature to be at 30 DEG C., and through the tundish, enabling the molten steel to enter a thin strip caster, to form a molten pool in the crystallizer formed by rotating casting rolls and side block panels, and to be solidified and formed, wherein the thickness is 1.8 mm;

(68) after drawing out cast strips, cooling the cast strips to 1000 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 DEG C., the final rolling temperature is 900 DEG C., and the rolling reduction is 10%, and forming hot-rolled cast strips;

(69) cooling the hot-rolled cast strips to 550 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 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 DEG C., and the total rolling reduction is 70%, and forming warm-rolled strips;

(70) removing oxidized scales of the warm-rolled strips through pickling, and then performing cold rolling 7 times at 100-200 DEG C., wherein the total rolling reduction is 70%; during the cold rolling course, performing aging treatment 3 times, wherein the aging treatment temperature is 320 DEG C., and the duration is 240 s, and performing aging treatment each time between two adjacent cold rollings, so as to obtain cold rolled strips of which the thickness is 0.15 mm;

(71) performing recrystallization annealing on the cold rolled strips at 840-860 DEG C. for 120 s under the condition of nitrogen-hydrogen mixed atmosphere, wherein the dew point of the mixed atmosphere is controlled to be at 60 DEG C.; then coating with an MgO layer, and finally coiling so as to obtain coated cold-rolled strips, wherein the volume concentration of the hydrogen in the mixed atmosphere of nitrogen and hydrogen is 30%;

(72) 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, 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 DEG C. at the rate of 30-40 DEG C./h, and keeping the temperature for 30 h for purification annealing; and

(73) 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., and finally performing air-cooling to be at 650 DEG C. or below and coiling so as to obtain the oriented high silicon steel with magnetic properties: P.sub.10/50 at 0.37 W/kg, P.sub.10/400 at 7.2 W/kg, magnetic induction B.sub.8 at 1.75 T, and B.sub.8/B.sub.S=0.970.