A low iron loss and high magnetic induction non-oriented silicon steel strip and its preparation method and application

Abstract

The present invention provides a low-iron-loss, high-magnetic-induction non-oriented silicon steel strip, as well as its preparation method and application. This preparation method, through chemical composition adjustment and the use of vertical twin-roll casting and other processes, can directly form molten steel into a 1.5-3 mm thick strip, which is then directly hot-rolled. This preparation method is simple and energy-efficient, and the resulting non-oriented silicon steel strip exhibits excellent magnetic and mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel material preparation, and in particular relates to a production method of high-silicon non-oriented electrical steel, and non-oriented electrical steel prepared by the production method. Background Art

[0002] Vertical twin-roll thin strip casting technology is a production process that can directly cast and roll thin strip steel. It uses two counter-rotating copper rollers to solidify and form a continuous steel strip for continuous downward transmission. Compared with traditional hot rolling processes, this technology has the advantages of simple production procedures, short production lines, near-net shape, low energy consumption, and low product costs. In addition, because the vertical twin-roll thin strip casting technology has a high solidification cooling rate far higher than that of traditional processes, the sub-rapid solidification state it achieves can not only help reduce the adverse effects of element segregation, but also effectively avoid the formation of B2 and DO3 low plastic deformation Fe-Si structures under high silicon conditions, thereby reducing the difficulty of subsequent rolling.

[0003] As an important soft magnetic material, non-oriented electrical steel is often used in key components of electronic equipment such as motor stators (rotors) that need to work in a rotating magnetic field. As one of the key performance parameters for evaluating non-oriented electrical steel, iron loss and magnetic induction intensity are often the focus of attention. When used as a motor stator (rotor), the magnetic induction intensity of the non-oriented electrical steel material is related to the torque of the motor, while the iron loss, thermal conductivity, fatigue strength, etc. of the material are related to the maximum speed of the motor. Iron loss is generally considered to be composed of eddy current loss, hysteresis loss, and anomalous loss. In daily production life, the iron core is usually divided into thin sheets of low thickness and electrically isolated from each other by coating to reduce eddy current loss. This makes thinning an effective means of reducing thickness.

[0004] The thin strip casting process can directly produce near-net-shape thin strip products. Furthermore, the non-oriented electrical steel used in new energy vehicle motor stators and rotors requires a low thickness, which is perfectly suited to the thin strip casting process. Therefore, if the two can be combined to produce non-oriented electrical steel for new energy vehicle motor stators and rotors using the thin strip casting process, it will make a due contribution to promoting green development.

[0005] CN114606435A discloses a traditional process for producing non-oriented electrical steel strip, which includes smelting, refining outside the furnace, continuous casting of thick slabs, slab reheating, hot rolling, normalizing, cold rolling, annealing, insulation coating, shearing, and packaging. This process first casts the molten steel into a 35-40 mm thick ingot. The ingot is then repeatedly heated to 1150°C and held for 2 hours. The ingot is then rolled through seven passes to produce a 1.5-2.0 mm thick hot-rolled sheet. The hot-rolled sheet is then normalized at 900-950°C, cold rolled twice to a thickness of 0.2-0.4 mm, and annealed. However, in this technology, the initial thickness of the molten steel after casting and rolling is 35-40 mm, so it is necessary to repeatedly heat it to 1150 ° C and keep it at this temperature for 2 hours, and to waste energy to roll the thick plate seven times to obtain a 1.5-2.0 mm thick hot-rolled plate. This makes the production process complicated, the production process long, the cost high, and the production speed slow. In addition, the deformation required from the 35-40 mm thick ingot to the 1.5-2.0 thick hot-rolled plate is too large, which destroys the original columnar crystal {001} <uvw>texture, resulting in severe deterioration of the texture, smaller grain size, low magnetic induction and high iron loss.

[0006] In addition, CN114606445A discloses a method for producing non-oriented silicon steel, non-oriented silicon steel and its applications; CN108330397A discloses a method for preparing ultra-thin strips of non-oriented silicon steel with low iron loss and high magnetic induction; CN108085603A discloses a method for preparing high-grade non-oriented silicon steel based on thin strip continuous casting; CN108504932A discloses a method for preparing ultra-thin strips of non-oriented silicon steel based on thin strip continuous casting. The above disclosed technologies still have the following problems:

[0007] (1) The aluminum content in the composition is prone to cause outlet blockage when nitrogen is used as cooling gas. When the aluminum content is limited to avoid the outlet blockage problem, it is difficult to avoid the adverse effects of small-sized AlN precipitates on grain growth during subsequent annealing;

[0008] (2) The low manganese content in the composition and the extremely thin product size after cold rolling pose challenges to the yield strength of the material. Since the motor generates a large centrifugal force when rotating at high speed, the rotor core magnetic bridge and other weak points are prone to fracture, making it difficult to ensure the safety of the motor at high speed;

[0009] (3) Under the combined influence of the AlN inclusions and the final annealing process mentioned in (1), the iron loss of the product did not decrease to the value that the product should have at this thickness. Summary of the Invention

[0010] In order to solve the above problems, the purpose of the present invention is to provide a low iron loss and high magnetic induction non-oriented silicon steel strip and its preparation method and application. The preparation method is simple and has low energy consumption, and the non-oriented silicon steel strip obtained has excellent magnetic and mechanical properties.

[0011] In order to achieve the above object, the present invention provides a method for preparing a low iron loss and high magnetic induction non-oriented silicon steel strip, which comprises the following steps:

[0012] (1) smelting molten steel, wherein the composition of the molten steel comprises, by mass percentage, C≤0.008%, Si 2.5-3.8%, Al≤0.01%, Mn 0.50-1.75%, P≤0.02%, S≤0.005%, Nb≤0.002%, V≤0.002%, Cr≤0.002% and Ti≤0.002%, with the balance being Fe;

[0013] (2) casting the molten steel into a cast strip with a thickness of 1.0-2.5 mm using a twin-roll casting mill;

[0014] (3) when the temperature of the cast strip is lowered to 850-1200°C, a single-pass hot rolling is performed with a hot rolling reduction rate of 20-50%, and then coiling is performed at 550-700°C to obtain a hot-rolled strip with a thickness of 1.0-1.6 mm;

[0015] (4) cold rolling the hot-rolled strip to obtain a cold-rolled strip having a thickness of 0.2-0.35 mm;

[0016] (5) performing hood annealing or continuous annealing on the cold-rolled strip;

[0017] (6) cooling to room temperature and coating to obtain the low iron loss and high magnetic induction non-oriented silicon steel strip;

[0018] Wherein, in step (4), the cold rolling is performed by one of the following methods:

[0019] Method 1: The hot-rolled strip is subjected to secondary cold rolling with intermediate annealing to obtain a cold-rolled strip with a thickness of 0.2-0.35 mm;

[0020] Method 2: The hot-rolled strip is kept in a bell-type annealing furnace at 800-1000° C. in a mixed atmosphere of hydrogen and protective gas for 1-10 minutes, pickled, and then cooled to obtain a normalized strip; the normalized strip is subjected to secondary cold rolling with intermediate annealing to obtain a cold-rolled strip with a thickness of 0.2-0.35 mm;

[0021] Method 3: The hot-rolled strip is kept in a bell-type annealing furnace at 800-1000° C. in a mixed atmosphere of hydrogen and protective gas for 1-10 minutes, pickled, and then cooled to obtain a normalized strip; the normalized strip is directly cold-rolled to a thickness of 0.2-0.35 mm to obtain a cold-rolled strip.

[0022] According to a specific embodiment of the present invention, preferably, the mixture of hydrogen and protective gas is a mixture of hydrogen and argon or a mixture of hydrogen and nitrogen.

[0023] According to a specific embodiment of the present invention, preferably, the hydrogen content in the mixture of hydrogen and argon is 25-65 vol%, and the nitrogen content in the mixture of hydrogen and nitrogen is 25-65 vol%.

[0024] According to a specific embodiment of the present invention, preferably, in the method 1 and the method 2 of step (4), the secondary cold rolling of the strip intermediate annealing is: the first cold rolling to a thickness of 0.5-0.75 mm, with a reduction rate of not more than 60%, intermediate annealing for 1-3 minutes at 800-1000 ° C and a mixed atmosphere of hydrogen and protective gas, and then cooling to room temperature; the second cold rolling to a thickness of 0.2-0.35 mm, with a reduction rate of 10-35%, to obtain a cold-rolled strip.

[0025] According to a specific embodiment of the present invention, preferably, in step (5), the bell annealing is: bell annealing is performed at 900-1200° C. in an atmosphere of a mixture of hydrogen and protective gas, and the annealing time is 0.1-1 hr.

[0026] According to a specific embodiment of the present invention, preferably, in step (5), the continuous annealing is: continuous annealing is performed at 900-1200° C. in an atmosphere of a mixture of hydrogen and protective gas, and the annealing time is 1-10 min.

[0027] According to a specific embodiment of the present invention, preferably, in step (6), the coating is applied after cooling to room temperature at a rate of no more than 10°C / s.

[0028] According to a specific embodiment of the present invention, preferably, in step (2), when the molten steel is cast by a twin-roll caster, it is controlled under a nitrogen environment, and the molten steel flows into the molten pool through a tundish, a transition ladle, and a flow distributor, and the molten steel is cast by a vertical twin-roll thin strip caster to obtain the cast strip; thereafter, the cast strip passes through a closed chamber and is uniformly cooled to 1000-1200°C in an environment of nitrogen or a mixture of hydrogen and nitrogen, with a cooling time of less than 60s and a cooling rate of no more than 20°C / s.

[0029] According to a specific embodiment of the present invention, preferably, the degree of superheat is not greater than 100° C., and the solidification cooling rate of the cast strip is 1500-2000° C. / s.

[0030] According to a specific embodiment of the present invention, preferably, the equiaxed crystal region of the cast strip is less than 20%.

[0031] According to a specific embodiment of the present invention, preferably, in step (2), when the molten steel is cast into a thin strip using a twin-roll casting mill, the contact time between the molten steel in the molten pool and the crystallization roll surface is 0.1-0.4s.

[0032] The present invention also provides a low iron loss and high magnetic induction non-oriented silicon steel thin strip prepared by the above-mentioned method for preparing the low iron loss and high magnetic induction non-oriented silicon steel thin strip.

[0033] The present invention also provides the use of the above-mentioned low iron loss and high magnetic induction non-oriented silicon steel thin strip in automobile drive motors.

[0034] According to a specific embodiment of the present invention, the above preparation method specifically comprises the following steps:

[0035] (1) smelting molten steel, wherein the chemical composition of the final molten steel is calculated as follows by mass percentage: C ≤ 0.008%, Si: 2.5-3.8%, Al ≤ 0.01%, Mn: 0.50-1.75%, P ≤ 0.02%, S ≤ 0.005%, Nb ≤ 0.002%, V ≤ 0.002%, Cr ≤ 0.002%, Ti ≤ 0.002%, and the remainder is iron and unavoidable impurities;

[0036] (2) Under nitrogen atmosphere, molten steel flows into the molten pool through the tundish, transition ladle, and flow distributor, and is cast and rolled into a thin strip (cast strip) by a vertical twin-roll thin strip casting and rolling mill. The superheat is not greater than 100°C, the thickness is 1.0-2.5mm, and the solidification cooling rate is 1500-2000°C / s. By controlling the flow distributor, molten pool depth, casting and rolling speed, etc., the equiaxed crystal area of the cast and rolled strip is less than 20%;

[0037] (3) The cast strip passes through a closed chamber and is uniformly cooled to 1000-1200°C in a nitrogen (or hydrogen and nitrogen mixture) environment. The cooling time is less than 60s and the cooling rate is no more than 20°C / s.

[0038] (4) When the temperature of the cast strip is uniformly reduced to 850-1200°C, a single-pass hot rolling is performed with a hot rolling reduction rate of 20-50%, and then the hot-rolled strip is coiled at 550-700°C to obtain a hot-rolled strip with a thickness of 1.0-1.6 mm;

[0039] (5) The hot-rolled strip is subjected to secondary cold rolling with intermediate annealing: the first cold rolling is performed to a thickness of 0.5-0.75 mm with a reduction rate of no more than 60%, and intermediate annealing is performed at 800-1000° C. in a hydrogen-argon mixture (25 vol% H 2 ) atmosphere for 1-3 min, followed by cooling to room temperature; the second cold rolling is performed to a thickness of 0.2-0.35 mm with a reduction rate of 10-35% to obtain a cold-rolled strip;

[0040] (6) hood annealing the cold-rolled strip at 900-1200° C. in a hydrogen-argon mixed gas (25 vol% H 2 ) atmosphere for 0.1-1 hr; then cooling the strip to room temperature at a rate of no more than 10° C. / s and coating the strip to obtain the low iron loss and high magnetic induction non-oriented silicon steel strip;

[0041] In the above method, starting from step (5), the following steps can also be followed:

[0042] (5) directly annealing the hot-rolled strip in a bell-type annealing furnace at 800-1000° C. in a hydrogen-argon mixed gas (25 vol% H 2 ) atmosphere for 1-10 min, followed by pickling and cooling to obtain a normalized strip;

[0043] (6) The normalized strip is subjected to secondary cold rolling with intermediate annealing: the first cold rolling is performed to a thickness of 0.5-0.75 mm with a reduction rate of no more than 60%; the intermediate annealing is performed at 800-1000°C in a hydrogen and argon mixed gas (25 vol% H2) atmosphere for 1-3 minutes, and then cooled to room temperature; the second cold rolling is performed to a thickness of 0.2-0.35 mm with a reduction rate of 10-35% to obtain a cold-rolled strip;

[0044] Alternatively, the normalized strip is directly cold rolled to a thickness of 0.2-0.35 mm using a process to obtain a cold-rolled strip;

[0045] (7) The cold-rolled strip is subjected to hood annealing: the annealing is carried out at 900-1200°C in a hydrogen and argon mixed gas (25 vol% H2) atmosphere for 0.1-1 hr; thereafter, the strip is cooled to room temperature at a rate of no more than 10°C / s and coated to obtain the low iron loss and high magnetic induction non-oriented silicon steel strip; wherein, the annealing can also be carried out by a continuous annealing process at 900-1200°C in a hydrogen and argon mixed gas (25 vol% H2) atmosphere or a hydrogen and nitrogen mixed gas (25 vol% H2) atmosphere.

[0046] In view of the problems that the traditional process of preparing ultra-thin strips of non-oriented electrical steel from medium and thick plates or ingots is complicated, energy-consuming and time-consuming, and the existing vertical twin-roll casting and rolling equipment is used to prepare ultra-thin strips of non-oriented electrical steel with insufficient yield strength and magnetic properties, the present invention provides a method for preparing low-thickness, low-iron-loss and high-magnetic-induction non-oriented silicon steel strips using vertical twin-roll thin strip casting and rolling technology. The method is based on vertical twin-roll thin strip casting and rolling, secondary cold rolling, and hood annealing to influence the evolution of grain size and texture distribution, thereby controlling the magnetic properties and mechanical properties of the product: the present invention can directly form molten steel into a thin strip with a thickness of 1.5-3 mm by adjusting the chemical composition, adopting a protective atmosphere (such as nitrogen), and using a vertical twin-roll casting and rolling process, and directly hot rolling, thereby eliminating a large amount of time and energy loss in repeated rolling and repeated heating before hot rolling; at the same time, due to the reduction in the deformation required by the process of the present invention, the original columnar crystal {001} can be retained to a large extent. <uvw>The invention optimizes the texture, thereby optimizing the texture distribution and grain size, and promoting the final magnetic properties. Furthermore, the invention improves the composition of the molten steel, avoiding outlet blockage caused by aluminum and nitrogen shielding gas, and reducing the adverse effects of AlN inclusions. The invention optimizes the manganese content, increasing product strength without reducing ductility. The invention also optimizes the heat treatment process to enhance the final magnetic properties. The low-thickness, low-iron-loss, high-magnetic-induction non-oriented silicon steel strip produced using this method can be mass-produced and applied in automotive drive motors.

[0047] The present invention has the following beneficial effects:

[0048] 1. Compared with the conventional method for preparing low-thickness, high-grade non-oriented electrical steel, the present invention controls the Al content, making it possible to adopt a vertical twin-roll thin strip casting process under nitrogen environment and sub-rapid solidification. As a result, cast strips with a thickness of 1.0-2.5 mm can be directly cast and rolled. The microstructure of the cast strips is refined and uniform, the composition is evenly distributed (with low segregation), the solid solubility is expanded, and a supersaturated solid solution is formed.

[0049] 2. Compared with the conventional method for preparing low-thickness, high-grade non-oriented electrical steel, the present invention adopts a nitrogen environment for casting and rolling. In addition to controlling the contents of C, S, and P, the present invention also controls the contents of Al, Cr, Sb, and Ti to reduce the harmful effects of small-sized inclusions.

[0050] 3. Compared with the conventional method for preparing low-thickness and high-grade non-oriented electrical steel, the present invention obtains the solid solution strengthening effect by adopting sub-rapid solidification and provides conditions for dispersion strengthening, so that the product can obtain ideal mechanical properties (yield strength Rp 0.2 500-550Mpa, R m 580-720 MPa, elongation 12.0-14.6%);

[0051] 4. The cast strip products directly cast and rolled by the vertical twin-roll thin strip casting process usually have small grains, which is not conducive to magnetic properties. Compared with the conventional low-thickness and high-grade non-oriented electrical steel production method, the present invention adopts secondary cold rolling with intermediate annealing and hood annealing process to adjust the grain size, texture distribution, etc., so as to obtain thin strip products with ideal magnetic properties (medium frequency iron loss P 1.0 / 400 7-14W / kg, magnetic induction B 50 is 1.67-1.71T). BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Schematic diagram of the preparation process of non-oriented silicon steel strip;

[0053] Figure 2 This is the metallographic structure diagram of the non-oriented silicon steel ultra-thin strip prepared in Example 1;

[0054] Figure 3 This is the metallographic structure diagram of the non-oriented silicon steel ultra-thin strip prepared in Example 2.

[0055] Explanation of symbols:

[0056] 1: Ladle; 2: Vertical twin-roll strip casting mill; 3: Cast and rolled strip; 4: Pinch roll; 5: Hot rolling stand; 6: Water-cooled roller table; 7: Flying shear; 8: Coiler; 9: Cold rolling mill; 10: Annealing furnace; 11: Hood annealing furnace. DETAILED DESCRIPTION

[0057] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0058] The preparation method of the present invention is as follows Figure 1 As shown, the specific process can be:

[0059] Molten steel enters the vertical twin-roll thin strip casting mill 2 from the ladle 1 for casting and rolling to obtain a cast strip 3;

[0060] The cast strip 3 passes through the pinch roll 4 and enters the hot rolling stand 5 for hot rolling. It then passes through the water-cooled roller 6 for cooling, the flying shear 7 for trimming, and the coiler 8 for coiling to obtain the hot rolled strip.

[0061] The hot-rolled strip is cold-rolled by two sets of cold rolling mills 9 , and an annealing furnace 10 is provided between the two sets of cold rolling mills 9 for intermediate annealing. After cold rolling, the strip enters a bell-type annealing furnace 11 for annealing.

[0062] Example 1

[0063] This embodiment provides a low iron loss and high magnetic induction non-oriented silicon steel thin strip, which is prepared by the following steps:

[0064] (1) Smelting: Molten steel is obtained by smelting, and its chemical composition, calculated by mass percentage, is as follows: 0.003% C, 3.7% Si, 0.005% Al, 1.6% Mn, 0.01% P, 0.003% S, Nb≤0.001%, V≤0.001%, Cr≤0.001%, Ti≤0.001%; the remainder is iron and unavoidable impurities;

[0065] (2) Casting: In a nitrogen environment, the molten steel flows into the molten pool through the tundish, transition ladle, and flow distributor, and is cast into thin strips by a vertical twin-roll thin strip caster. The superheat is 50°C, the cast strip thickness is 1.8mm, the solidification cooling rate is 1700-1750°C / s, and the volume of the equiaxed crystal region in the cast strip is less than 10%;

[0066] (3) Hot rolling: The cast strip was uniformly cooled to 1100°C in a nitrogen atmosphere and then hot rolled in a single pass. The hot rolled strip was then coiled at 550°C to obtain a 1.0 mm thick hot rolled strip.

[0067] (4) Secondary cold rolling with intermediate annealing: The hot-rolled strip is cold-rolled to 0.5 mm, intermediate annealed at 950 ° C in a hydrogen-argon mixture (25 vol% H2) atmosphere for 2.5 min, then cooled to room temperature at a cooling rate of no more than 10 ° C / s, and the intermediate annealed sheet is cold-rolled to 0.25 mm thick for the second time;

[0068] (5) Hood annealing: annealing for 15 min at 1100°C in a hydrogen-argon mixed gas (25 vol% H2) atmosphere, cooling to room temperature at a rate of no more than 10°C / s, and coating to obtain the low-thickness low-iron-loss high-magnetic-induction non-oriented silicon steel strip. The metallographic structure is shown in FIG. Figure 2 shown.

[0069] Mechanical properties of the obtained product: yield strength Rp 0.2 540Mpa; R m 700MPa; elongation is 12.8%;

[0070] Magnetic properties: medium frequency iron loss P 1.0 / 400 13.0W / kg; magnetic induction B 50 It is 1.69T.

[0071] Example 2

[0072] This embodiment provides a low iron loss and high magnetic induction non-oriented silicon steel thin strip, which is prepared by the following steps:

[0073] (1) Smelting: Molten steel is obtained by smelting, and its chemical composition, calculated by mass percentage, is as follows: 0.002% C, 3.6% Si, 0.010% Al, 1.5% Mn, 0.01% P, 0.002% S, Nb≤0.001%, V≤0.001%, Cr≤0.001%, Ti≤0.001%; the remainder is iron and unavoidable impurities;

[0074] (2) Casting: In a nitrogen environment, the molten steel flows into the molten pool through the tundish, transition ladle, and flow distributor, and is cast into thin strips by a vertical twin-roll thin strip caster. The superheat is 45°C, the cast strip thickness is 2.0 mm, the solidification cooling rate is 1700-1750°C / s, and the volume of the equiaxed crystal region in the cast strip is less than 10%;

[0075] (3) Hot rolling: The cast strip was uniformly cooled to 1100°C in a nitrogen atmosphere and then hot rolled in a single pass. The hot rolled strip was then coiled at 550°C to obtain a 1.1 mm thick hot rolled strip.

[0076] (4) Normalizing: The hot-rolled strip is directly annealed in a bell-type annealing furnace at 800-1000°C in a hydrogen-argon mixture (25 vol% H2) atmosphere for 2 min, pickled, and then cooled to obtain a normalized strip;

[0077] (5) Secondary cold rolling with intermediate annealing: The normalized strip is cold rolled to 0.5 mm, intermediate annealed for 2 min at 1000 °C in a hydrogen-argon mixture (25 vol% H2) atmosphere, then cooled to room temperature at a cooling rate of no more than 10 °C / s, and the intermediate annealed sheet is cold rolled to 0.3 mm in thickness for the second time;

[0078] (6) Hood annealing: annealing for 25 min at 1100°C in a hydrogen-argon mixed gas (25 vol% H2) atmosphere, cooling to room temperature at a rate of no more than 10°C / s, and coating to obtain the low-thickness low-iron-loss high-magnetic-induction non-oriented silicon steel strip. The metallographic structure is shown in FIG. Figure 3 shown.

[0079] Mechanical properties of the obtained product: yield strength Rp 0.2 510Mpa; R m 595MPa; elongation is 13.2%;

[0080] Magnetic properties: medium frequency iron loss P 1.0 / 400 8.5W / kg; magnetic induction B 50 It is 1.70T.

[0081] The low iron loss and high magnetic induction non-oriented silicon steel strip prepared by the preparation method provided by the present invention has excellent magnetic and mechanical properties: yield strength Rp 0.2 500-550Mpa, R m 580-720MPa, elongation 12.0-14.6%; medium frequency iron loss P 1.0 / 400 7-14W / kg, magnetic induction B 50 The preparation method is simple and the energy consumption is low.< / uvw> < / uvw>

Claims

1. A method for preparing a low iron loss and high magnetic induction non-oriented silicon steel strip, comprising the following steps: (1) smelting molten steel, wherein the composition of the molten steel comprises, by mass percentage, C≤0.008%, Si 2.5-3.8%, Al≤0.01%, Mn 0.50-1.75%, P≤0.02%, S≤0.005%, Nb≤0.002%, V≤0.002%, Cr≤0.002% and Ti≤0.002%, with the balance being Fe; (2) casting the molten steel into a cast strip with a thickness of 1.0-2.5 mm using a twin-roll casting mill; (3) when the temperature of the cast strip is lowered to 850-1200°C, a single-pass hot rolling is performed with a hot rolling reduction rate of 20-50%, and then coiling is performed at 550-700°C to obtain a hot-rolled strip with a thickness of 1.0-1.6 mm; (4) cold rolling the hot-rolled strip to obtain a cold-rolled strip having a thickness of 0.2-0.35 mm; (5) performing hood annealing or continuous annealing on the cold-rolled strip; (6) cooling to room temperature and coating to obtain the low iron loss and high magnetic induction non-oriented silicon steel strip; Wherein, in step (4), the cold rolling is performed by one of the following methods: Method 1: The hot-rolled strip is subjected to secondary cold rolling with intermediate annealing to obtain a cold-rolled strip with a thickness of 0.2-0.35 mm; Method 2: The hot-rolled strip is kept in a bell-type annealing furnace at 800-1000° C. in a mixed atmosphere of hydrogen and protective gas for 1-10 minutes, pickled, and then cooled to obtain a normalized strip; the normalized strip is subjected to secondary cold rolling with intermediate annealing to obtain a cold-rolled strip with a thickness of 0.2-0.35 mm; Method 3: The hot-rolled strip is kept in a bell-type annealing furnace at 800-1000° C. in a mixed atmosphere of hydrogen and protective gas for 1-10 minutes, pickled, and then cooled to obtain a normalized strip; the normalized strip is directly cold-rolled to a thickness of 0.2-0.35 mm to obtain a cold-rolled strip.

2. The preparation method according to claim 1, wherein The mixed gas of hydrogen and protective gas is a mixed gas of hydrogen and argon or a mixed gas of hydrogen and nitrogen.

3. The preparation method according to claim 2, wherein The hydrogen content in the mixed gas of hydrogen and argon is 25-65 vol%, and the nitrogen content in the mixed gas of hydrogen and nitrogen is 25-65 vol%.

4. The preparation method according to claim 1, wherein In the first and second methods of step (4), the secondary cold rolling of the strip with intermediate annealing is as follows: the first cold rolling is to a thickness of 0.5-0.75 mm, with a reduction rate of no more than 60%, and the intermediate annealing is carried out at 800-1000° C. in an atmosphere of a mixture of hydrogen and protective gas for 1-3 minutes, and then cooled to room temperature; the second cold rolling is to a thickness of 0.2-0.35 mm, with a reduction rate of 10-35%, to obtain a cold-rolled strip.

5. The preparation method according to claim 1, wherein In step (5), the bell annealing is performed at 900-1200° C. in a mixed atmosphere of hydrogen and protective gas, and the annealing time is 0.1-1 hr.

6. The preparation method according to claim 1, wherein In step (5), the continuous annealing is performed at 900-1200° C. in a mixed atmosphere of hydrogen and protective gas, and the annealing time is 1-10 minutes.

7. The preparation method according to claim 1, wherein In step (6), the coating is applied after cooling to room temperature at a rate of no more than 10°C / s.

8. The preparation method according to claim 1, wherein In step (2), when the molten steel is cast by a twin-roll caster, the molten steel is flowed into the molten pool through a tundish, a transition ladle, and a flow distributor under a nitrogen environment, and the molten steel is cast by a vertical twin-roll thin strip caster to obtain the cast strip; Afterwards, the cast strip passes through a closed chamber and is evenly cooled to 1000-1200°C in a nitrogen or hydrogen and nitrogen mixture environment. The cooling time is less than 60s and the cooling rate is no more than 20°C / s.

9. The preparation method according to claim 8, wherein The overheating degree is not greater than 100° C., and the solidification cooling rate of the cast strip is 1500-2000° C. / s.

10. The preparation method according to claim 8, wherein The equiaxed crystal region of the cast strip is less than 20%.

11. The preparation method according to claim 1, wherein In step (2), when the molten steel is cast into a thin strip using a twin-roll casting mill, the contact time between the molten steel in the molten pool and the surface of the crystallization roll is 0.1-0.4s.

12. A low iron loss and high magnetic induction non-oriented silicon steel strip produced by the method for producing a low iron loss and high magnetic induction non-oriented silicon steel strip according to any one of claims 1 to 11.

13. Use of the low iron loss and high magnetic induction non-oriented silicon steel strip according to claim 12 in automobile drive motors.

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