A method for preparing an extremely thin non-oriented silicon steel with low magnetic anisotropy

Abstract

A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy, belonging to the field of non-oriented silicon steel production technology, includes the following steps: smelting molten steel according to a set chemical composition; continuous casting, hot rolling, pickling, first-stage cold rolling, intermediate annealing, second-stage cold rolling, finished product annealing, and coating to obtain non-oriented silicon steel with a thickness of 0.10mm~0.15mm. This invention, through the synergistic control of a two-stage high-reduction-rate cold rolling process and an intermediate low-temperature annealing process, forms a relatively uniform, continuous, medium-strength γ-fiber recrystallization texture and a relatively weak recrystallization texture on the finished annealed plate. This achieves the purpose of reducing magnetic anisotropy and increasing the magnetic flux density B. 50 Anisotropy ≤ 0.5%, iron loss P 10 / 400 Anisotropy ≤ 4%, iron loss P 10 / 1000 Anisotropy ≤ 4%.

Description

Technical Field

[0001] This invention belongs to the field of non-oriented silicon steel production technology, specifically relating to a method for preparing ultra-thin non-oriented silicon steel with low magnetic anisotropy. Background Technology

[0002] Non-oriented silicon steel is an important soft magnetic material for manufacturing the cores of variable frequency motors and drive motors. With the rise of emerging industries such as new energy vehicles, drones, and high-speed flywheel energy storage, there is a demand for motors to become smaller, faster, and more efficient. As motor speed increases, the magnetic field frequency gradually increases, leading to increased losses in the silicon steel. Therefore, non-oriented silicon steel is required to have low iron losses at high frequencies. At high frequencies, the iron losses of non-oriented silicon steel are mainly eddy current losses, which are proportional to the square of the steel plate thickness. Reducing the thickness of non-oriented silicon steel is a crucial means of reducing high-frequency iron losses. Currently, emerging industries have a significant demand for ultra-thin non-oriented silicon steel with a thickness of ≤0.15mm.

[0003] Magnetic anisotropy represents the difference in magnetic properties of non-oriented silicon steel in various directions, which has a significant impact on the operational stability and energy efficiency of motors. If the non-oriented silicon steel used to make the motor core has high magnetic anisotropy, the magnetic flux density and core losses will vary significantly in different directions, resulting in differences in magnetostriction, Lorentz force, and heat generation. This severely affects the motor's operational stability and efficiency, leading to a shorter motor lifespan, increased maintenance costs, and increased safety risks. Furthermore, high magnetic anisotropy in non-oriented silicon steel makes the motor's magnetic circuit distribution and cooling system more complex, increasing manufacturing difficulty and cost. Therefore, developing new, ultra-thin non-oriented silicon steels with low magnetic anisotropy is essential.

[0004] Patent CN111440992B discloses a low-anisotropy non-oriented silicon steel for hydropower generation and its production method. The main controlled processes involve reducing the anisotropy of the material through a routine single-pass cold rolling process, the addition of boron (B) and copper (Cu) alloying elements, controlling the proportion of equiaxed grains in the cast billet, and controlling the heating rate and unit tension during recrystallization annealing. It primarily targets 0.50mm non-oriented silicon steel with a magnetic flux density of B... 50 ≥1.65T, iron loss P 15 / 50 ≤2.40W / kg, iron loss P 15 / 50 Anisotropy <10%.

[0005] Patent CN114318127B discloses a method for producing non-oriented silicon steel with ultra-low anisotropy for ultra-large generators. The main controlled process involves a frequent single-pass cold rolling process, followed by continuous annealing using low-tension control technology to improve the material's transverse magnetic properties and reduce magnetic anisotropy. The resulting 0.50mm thick non-oriented silicon steel has an iron loss P...15 / 50 ≤2.5W / kg, magnetic field strength B 50 ≥1.65T, iron loss P 15 / 50 Anisotropy ≤ 8%.

[0006] Patent CN107630131B discloses a production method for improving the anisotropy of electromagnetic properties in electrical steel products. This method primarily involves controlling the tension of the steel strip entering the furnace during annealing to maintain the elongation of the cold-rolled steel strip within the range of 0.10% to 5.00%; adjusting the overall length of the heating section and the rapid heating rate of the annealing furnace to control the heating rate of the cold-rolled steel strip at 400℃ / min to 850℃ / min. This reduces the magnetic differences in the longitudinal and transverse directions of the non-oriented silicon steel products, and decreases iron loss (P). 15 / 50 Anisotropy ≤ 6.5%.

[0007] Patent CN108203788B discloses a method for preparing low-magnetic anisotropy non-oriented silicon steel by thin-strip continuous casting. It mainly employs thin-strip continuous casting technology, controlling processes such as hot rolling and cold rolling reduction rates, and finished product annealing cooling rates to reduce magnetic anisotropy. The resulting product exhibits a circumferential average magnetic flux density B. 50 ≥1.70T, magnetic field strength B 50 Anisotropy < 5%.

[0008] Patent CN116790999A discloses a high-grade non-oriented silicon steel with low magnetic anisotropy and its preparation method. Targeting Si content of 2.8%~3.5%, it employs a routine single-pass cold rolling process. Through chemical composition optimization, such as adding appropriate amounts of Sn, adjusting the cold rolling reduction rate to 70%~85%, and controlling the finished product annealing with low tension ≤3MPa, the magnetic properties are improved and magnetic anisotropy is reduced. However, this invention mainly targets 0.50mm non-oriented silicon steel, and the finished product's iron loss (P) is... 15 / 50 ≤2.3W / kg, magnetic field strength B 50 ≥1.67T, iron loss P 15 / 50 Anisotropy ≤ 8%.

[0009] Non-oriented silicon steel can be classified into 0.50mm, 0.35mm, 0.20mm specifications and an ultra-thin series of ≤0.15mm based on thickness standards. As can be seen from the aforementioned patented technologies, existing technologies for reducing the magnetic anisotropy of non-oriented silicon steel mainly focus on 0.50mm thick products, and primarily on magnetic anisotropy at low frequencies. Mid-to-high frequency magnetic anisotropy and ultra-thin products are largely unaddressed, and the magnetic anisotropy remains relatively high, making it difficult to meet the increasingly demanding requirements of high-performance motors. Compared to conventional 0.50mm or 0.35mm thick products, the preparation of ultra-thin non-oriented silicon steel often requires high-reduction-rate cold rolling, resulting in the formation of {111} in the finished annealed sheet. <112> The component aggregates exhibit an uneven, intense γ-recrystallization texture, accompanied by strong [unclear text - possibly a typo]. Recrystallization texture. These texture features lead to severe magnetic anisotropy. Currently, the commonly used one-stage or two-stage cold rolling process for producing ultra-thin non-oriented silicon steel cannot achieve a uniform, continuous γ-fiber recrystallization texture, and is accompanied by strong... Due to the recrystallization texture, it is difficult to significantly reduce the magnetic anisotropy of extremely thin non-oriented silicon steel.

[0010] In summary, in order to meet the increasingly stringent requirements of high-performance motors for the magnetic anisotropy of ultra-thin non-oriented silicon steel, further improve the stability and safety of motor operation and the service life of motors, and reduce manufacturing difficulty and cost, it is urgent to develop a method for preparing ultra-thin non-oriented silicon steel with low magnetic anisotropy. Summary of the Invention

[0011] This invention addresses the technical bottleneck of magnetic anisotropy control in existing non-oriented silicon steel manufacturing processes by providing a method for preparing ultra-thin non-oriented silicon steel with low magnetic anisotropy. Molten steel, smelted according to a predetermined composition, undergoes continuous casting, hot rolling, and pickling. Then, it sequentially undergoes a first-stage cold rolling (total reduction ≥ 80%), intermediate low-temperature annealing (controlling the average grain size of the annealed plate to ≤ 40 μm), a second-stage cold rolling (total reduction ≥ 85%), finished product annealing, and coating treatment to prepare ultra-thin non-oriented silicon steel with a thickness of 0.10 mm to 0.15 mm. This invention, through the synergistic control of a two-stage high-reduction-rate cold rolling process and an intermediate low-temperature annealing process, achieves a uniform, continuous, medium-strength γ-fiber recrystallization texture and relatively weak magnetic anisotropy in the finished annealed plate. The recrystallization texture significantly reduces magnetic anisotropy, resulting in ultrathin non-oriented silicon steel with low magnetic anisotropy.

[0012] A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy specifically includes the following steps:

[0013] (1) Steel is smelted and continuously cast ingots are made according to the composition of Si mass percentage ≥ 3.0%. The continuously cast ingots are heated and hot rolled. The resulting hot rolled plates are shot blasted and pickled to obtain pickled plates.

[0014] (2) The pickled plate is cold rolled, and the total cold rolling reduction rate is controlled to be ≥80% to obtain a single cold rolled plate;

[0015] (3) Anneal the cold-rolled plate in one step, with the temperature of the soaking zone being 750℃~800℃ and the holding time in the soaking zone being 3min~5min, to obtain an intermediate annealed plate with an average grain size ≤40μm;

[0016] (4) The intermediate annealed plate is cold rolled, and the total cold rolling reduction rate is controlled to be ≥85% to obtain the secondary cold rolled plate;

[0017] (5) The secondary cold-rolled sheet is annealed, then coated with an insulating layer, dried and sintered to obtain a non-oriented silicon steel finished sheet;

[0018] The thickness of the non-oriented silicon steel finished plate is 0.10mm~0.15mm, and the magnetic induction intensity B is... 50 Anisotropy ≤ 0.5%, iron loss P 10 / 400 Anisotropy ≤ 4%, iron loss P 10 / 1000 Anisotropy ≤ 4%.

[0019] in:

[0020] In step (1), the chemical composition of the molten steel, by mass percentage, includes Si: 3.0%~4.0%, Al: 0.5%~1.0%, Mn: 0.3%~0.5%, Cr: 0.4%~1.2%, C≤0.0015%, S≤0.0015%, O≤0.0015%, N≤0.0015%, with the remainder being Fe and unavoidable impurities.

[0021] In step (1), the thickness of the continuous casting billet is 120mm~150mm; the continuous casting billet is heated to 1000℃~1050℃ and held for 90min~120min for hot rolling, the initial rolling temperature is 950℃~1000℃, the final rolling temperature is 860℃~910℃, the coiling temperature is 700℃~750℃, and after coiling, it is air-cooled to room temperature.

[0022] In step (1), the pickling uses hydrochloric acid solution with a mass concentration of 5% to 12% and a pickling temperature of 65℃ to 85℃.

[0023] In step (2), the pickled plate is preheated before cold rolling, and the preheating temperature is 80℃~150℃.

[0024] In step (3), the protective gas for the intermediate annealing of the cold-rolled plate is a mixture of hydrogen and nitrogen, with a hydrogen component of ≥15%.

[0025] In step (4), when the thickness of the intermediate annealing plate is ≥1.0mm, the intermediate annealing plate needs to be preheated before cold rolling, and the preheating temperature is 80℃~150℃; when the thickness of the intermediate annealing plate is <1.0mm, the intermediate annealing plate does not need to be preheated before cold rolling.

[0026] In step (5), the final product annealing soaking temperature is 900℃~1000℃, and the soaking time is 1min~2.5min; the dew point is controlled ≤-30℃; and the strip tension in the furnace is controlled ≤2N / mm. 2 The protective gas inside the furnace is a mixture of hydrogen and nitrogen, with hydrogen comprising ≥15%.

[0027] The principle for controlling the alloying elements and mass percentages of the non-oriented silicon steel prepared in this invention is as follows:

[0028] The Si content is 3.0%~4.0%, and the Al content is 0.5%~1.0%. Both Si and Al can increase the resistivity of the material and reduce eddy current losses. With increasing Si and Al content, the high-frequency iron loss of ultra-thin non-oriented silicon steel can be significantly reduced. However, increasing Si content increases rolling difficulty and makes strip breakage more likely during cold rolling. Al has a good deoxidizing effect in steelmaking; however, with increasing Al content, the viscosity of molten steel increases, making continuous casting more difficult. Therefore, in this invention, the Si content is controlled at 3.0%~4.0%, and the Al content is controlled at 0.5%~1.0%.

[0029] Mn: 0.3%~0.5%. Mn readily forms coarse MnS precipitates with S, reducing the harm to magnetic properties. Since the S content of this invention is ≤0.0015%, the Mn / S ratio is relatively high, which can promote the precipitation and growth of MnS, which is beneficial to magnetic properties.

[0030] Cr: 0.4%~1.2%. Cr helps increase resistivity and thus reduce eddy current losses. At the same time, because the atomic radius of Cr is small compared with that of Fe, the resulting lattice distortion is small, the resistance to dislocation slip is weak, which can reduce the brittleness of materials caused by high Si content and improve their rollability.

[0031] C≤0.0015%, S≤0.0015%, O<0.0015%, N≤0.0015%. C, S, O, and N are harmful elements and their content should be kept as low as possible.

[0032] The control principle of the process parameters of each process in this invention is as follows:

[0033] This invention, through the synergistic control of a two-stage high-reduction-rate cold rolling process and an intermediate low-temperature annealing process, forms a relatively uniform, continuous, and moderate-strength γ-fiber recrystallization texture in the finished annealed sheet, and significantly weakens... Recrystallization texture is used to reduce magnetic anisotropy. The specific control principles for the process parameters of each step are as follows:

[0034] (1) The present invention controls the thickness of the continuous casting billet to 120mm~150mm in order to ensure that it can still be hot-rolled to the target thickness under the subsequent heating process at a lower temperature. If the thickness of the continuous casting billet is higher than 150mm, the hot rolling load will increase under the lower heating temperature, making it difficult to roll to the target thickness. Moreover, the magnetic anisotropy will increase due to the excessive hot rolling total reduction rate. If the thickness of the continuous casting billet is lower than 120mm, the billet production efficiency of the continuous casting machine will be too low.

[0035] (2) In this invention, the hot rolling heating temperature is controlled at 1000℃~1050℃, and the holding time is 90min~120min. The relatively low heating temperature and short heating time used in the continuous casting billet heating process aim to ensure that the billet is thoroughly heated to achieve uniform temperature to meet the hot rolling requirements, while also preventing the formation of a large number of precipitates during subsequent hot rolling due to the significant solid solution of inclusion-forming elements, which would deteriorate the magnetic properties of the finished plate. Furthermore, if the heating temperature is below 1000℃, the hot rolling pressure is high, making it difficult to roll to the target thickness, resulting in large fluctuations in the thickness accuracy of the hot-rolled coil.

[0036] (3) In this invention, the initial rolling temperature is controlled at 950℃~1000℃, the final rolling temperature is controlled at 860℃~910℃, and the coiling temperature is controlled at 700℃~750℃. By using a lower initial rolling temperature, a higher final rolling temperature, and a higher coiling temperature, this invention aims to ensure the dimensional accuracy of the hot-rolled strip and increase the volume fraction of recrystallized grains in the hot-rolled plate. This provides the conditions for eliminating the normalizing process and also reduces the elongated deformed grains, thereby improving the anisotropy of the hot-rolled structure.

[0037] (4) In this invention, the hydrochloric acid concentration is 5%~12% and the pickling temperature is 65℃~85℃. The purpose is to remove the iron oxide scale on the surface of the hot-rolled plate and improve the surface quality of the strip steel. In this invention, the [Si]+[Al]+[Cr] alloy content is high, which increases the adhesion strength of the iron oxide scale on the strip steel. Therefore, a suitable pickling process is required to remove the iron oxide scale.

[0038] (5) Before the first stage of cold rolling, the pickled sheet needs to be preheated at a temperature of 80℃~150℃. On the one hand, as the [Si]+[Al] alloy content increases, the ductile-brittle transition temperature of the strip increases, and the cold rolling rollability decreases. Therefore, preheating is required to improve the cold rolling plasticity and prevent strip breakage and edge cracking. On the other hand, since the two-stage large reduction rate cold rolling control adopted in this invention results in a larger hot-rolled sheet thickness, the ductile-brittle transition temperature of the strip increases, and the cold rolling rollability decreases. Therefore, the pickled sheet needs to be preheated to improve rolling stability.

[0039] (6) First-stage cold rolling, controlling the total cold rolling reduction rate ≥80%, to obtain a primary cold-rolled sheet. This invention employs a relatively large first-stage cold rolling reduction rate to achieve higher deformation energy storage within the cold-rolled sheet and to form a stronger α-deformation texture (especially a stronger {111}) within the cold-rolled sheet. <110> The composition increases the driving force for recrystallization in the subsequent annealing process, thereby obtaining a stronger γ recrystallization texture (especially a stronger {111}). <112> (Components). If the total reduction rate is less than 80%, it is difficult to obtain a strong α-deformation texture (especially a strong {111}). <110> (Components).

[0040] (7) The present invention controls the temperature of the intermediate annealing soaking section to be 750℃~800℃, and the soaking time to be 3min~5min, in order to form recrystallized grains with an average grain size ≤40μm, thereby providing convenient conditions for obtaining higher deformation energy storage in the second stage of cold rolling. More importantly, relying on the higher deformation energy storage and stronger α deformation texture in the primary cold-rolled plate, the intermediate annealing at a lower temperature forms {111} <112> The components exhibit strong γ-recrystallization texture and strong [structure / effect]. Recrystallization texture. If the homogenization temperature is below 750℃ or the holding time is less than 3 minutes, it is difficult to obtain a fully recrystallized texture; if the homogenization temperature is above 800℃ or the holding time is greater than 5 minutes, an abnormally strong recrystallization texture will form. <112> The γ-recrystallization texture of component aggregation and the unusually strong Recrystallization texture. The protective gas in the annealing furnace is a mixed atmosphere of hydrogen and nitrogen (hydrogen component ≥15%) to prevent oxidation of the strip surface.

[0041] (8) Second-stage cold rolling, with a total cold rolling reduction rate ≥85%, to obtain a secondary cold-rolled sheet with a thickness of 0.10mm~0.15mm. The purpose is: on the one hand, to allow the smaller-sized grains in the intermediate annealed sheet to form a higher deformation energy storage inside the cold-rolled sheet after being deformed by cold rolling with a large reduction rate, thus providing convenient conditions for the recrystallization process of the final annealing; on the other hand, to allow the grains in the intermediate annealed sheet to form a higher deformation energy storage inside the cold-rolled sheet after being deformed by cold rolling with a large reduction rate, thus providing convenient conditions for the recrystallization process of the final annealing; <112> The strong γ-recrystallization texture of the aggregated components is transformed into a relatively strong {111} texture after cold rolling deformation with a large reduction rate. <112> And relatively strong {111} <110> The composition is characterized by deformed γ-fiber texture, and it makes the intermediate annealed plate more robust. The recrystallized texture transforms into a stronger α-deformation texture after cold rolling deformation with a large reduction rate. If the reduction rate is below 85%, a stronger {111} texture will be retained. <112> The components are difficult to obtain with relatively strong {111} <112> And relatively strong {111} <110> The composition is characterized by deformable γ-fiber texture, and it also retains a relatively strong... Texture, it is difficult to obtain a strong α-deformation texture.

[0042] (9) The finished product is annealed using a continuous annealing method. The temperature of the soaking zone is 900℃~1000℃, and the holding time in the soaking zone is 1min~2.5min. The purpose is to achieve complete recrystallization and grain coarsening (average grain size ≥90μm) by using a higher temperature annealing and matching an appropriate holding time, so as to reduce iron loss. In addition, it makes the secondary cold-rolled plate have a relatively strong {111} <112> And relatively strong {111} <110> The characteristic deformed γ-fiber texture and strong α-deformation texture are transformed into a more uniform, continuous, moderate-strength γ-fiber recrystallization texture and a weaker... Recrystallization texture reduces magnetic anisotropy. The protective gas in the annealing furnace is a hydrogen-nitrogen mixture (hydrogen integral ≥15%), and the dew point is controlled to ≤-30℃ to prevent strip surface oxidation and reduce damage to magnetic properties. Strip tension in the continuous annealing furnace is controlled to ≤2N / mm. 2 The purpose is to reduce the internal stress of the strip and minimize damage to its magnetic properties.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] (1) This invention, through the coordinated control of a two-stage high-reduction-rate cold rolling process and an intermediate low-temperature annealing process, forms a relatively uniform, continuous, and moderately strong γ-fiber recrystallization texture in the finished annealed plate. The recrystallization texture is weak, which significantly reduces magnetic anisotropy and thus the magnetic flux density B. 50 Anisotropy ≤ 0.5%, iron loss P 10 / 400 Anisotropy ≤ 4%, iron loss P 10 / 1000 Anisotropy ≤4%, compared to the anisotropy in traditional products {111} <112> Strong γ-recrystallization texture of component aggregation and strong The characteristics of recrystallization textures differ significantly.

[0045] (2) Compared with the traditional two-stage cold rolling method, the present invention eliminates the normalization process of hot-rolled plates, shortens the production process, and reduces production costs.

[0046] (3) The use of the ultra-thin non-oriented silicon steel of the present invention to make motors can improve the stability, safety and service life of motor operation and reduce manufacturing difficulty and maintenance costs. Attached Figure Description

[0047] Figure 1 A process flow diagram for preparing an ultrathin, non-oriented silicon steel with low magnetic anisotropy according to the present invention;

[0048] Figure 2 Microstructure images of the finished annealed plate prepared in Example 3 of this invention along the rolling direction and transverse direction;

[0049] Figure 3 Macroscopic texture diagram of the finished annealed plate prepared in Example 3 of this invention;

[0050] Figure 4 Microstructure images of the finished annealed plate prepared in Example 5 of this invention along the rolling direction and transverse direction;

[0051] Figure 5 Macroscopic texture diagram of the finished annealed plate prepared in Example 5 of this invention;

[0052] Figure 6Microstructure images of the finished annealed plate prepared in Comparative Example 2 of this invention along the rolling direction and transverse direction;

[0053] Figure 7 Macroscopic texture diagram of the finished annealed plate prepared in Comparative Example 2 of this invention;

[0054] Figure 8 Microstructure images of the finished annealed plate prepared in Comparative Example 6 of this invention along the rolling direction and transverse direction;

[0055] Figure 9 Macroscopic texture diagram of the finished annealed plate prepared in Comparative Example 6 of this invention. Detailed Implementation

[0056] Molten steel, smelted according to a set composition, undergoes continuous casting, hot rolling, and pickling. It then sequentially undergoes a first-stage cold rolling process (total reduction ≥80%), intermediate low-temperature annealing, a second-stage cold rolling process (total reduction ≥85%), finished product annealing, and coating treatment to produce ultra-thin non-oriented silicon steel with a thickness of 0.10mm~0.15mm. The process flow is as follows: Figure 1 This invention, through the synergistic control of a two-stage high-reduction-rate cold rolling process and an intermediate low-temperature annealing process, forms a relatively uniform, continuous, and moderately strong γ-fiber recrystallization texture and a relatively weak... Recrystallization texture.

[0057] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. The following are preferred embodiments of the present invention.

[0058] The microstructure observation involved in this invention was performed using a Leica metallurgical microscope. The macroscopic texture detection involved in this invention was performed using a Bruker D8 Discover X-ray diffractometer. The magnetic property detection involved in this invention was performed using a MATS-2010M silicon steel magnetic property measuring device, measuring the magnetic properties along the rolling direction and transverse direction of the finished annealed sheet, with a sample size of 100mm × 30mm. The measured parameters included magnetic flux density B. 50 and iron loss P 10 / 400 P 10 / 1000 Among them, B 50 P represents the magnetic flux density in a magnetic field with a strength of 5000 A / m. 10 / 400 P represents the iron loss under an alternating magnetic field with a magnetic induction intensity of 1.0T and a frequency of 400Hz. 10 / 1000This represents the iron loss under an alternating magnetic field with a magnetic flux density of 1.0T and a frequency of 1000Hz. Magnetic anisotropy is characterized according to the method specified in the national standard GB / T2521.1-2016 "All-Process Cold-Rolled Electrical Steel Part 1: Grain-Non-Oriented Steel Strip (Sheet)", and is divided into magnetic flux density anisotropy and iron loss anisotropy. Magnetic flux density anisotropy is the ratio of the difference between the rolling direction and the transverse direction magnetic flux density to the sum of the rolling direction and the transverse direction magnetic flux density; iron loss anisotropy is the ratio of the difference between the transverse direction and the rolling direction iron loss to the sum of the transverse direction and the rolling direction iron loss.

[0059] Example 1

[0060] A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy, the process flow diagram is as follows: Figure 1 As shown, the specific steps include:

[0061] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.07%, Al: 0.57%, Mn: 0.33%, Cr: 0.45%, C: 0.0011%, S: 0.0011%, O: 0.0013%, N: 0.0012%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 135 mm.

[0062] The continuously cast billet was heated to 1020℃ and held for 100 minutes, and then hot rolled. The initial rolling temperature was 967℃, the final rolling temperature was 885℃, and the coiling temperature was 736℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 5.0 mm.

[0063] The obtained hot-rolled plate was subjected to shot blasting and pickling. The pickling temperature was 70℃ and the pickling solution was hydrochloric acid with a mass concentration of 6%, resulting in a pickled plate.

[0064] (2) The pickled plate is preheated at 85°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 80% to obtain a cold-rolled plate with a thickness of 1.0 mm.

[0065] (3) Anneal the cold-rolled plate in one step. The temperature of the soaking zone is 780℃ and the soaking time is 4min. A mixture of hydrogen and nitrogen is used as the protective gas (hydrogen gas fraction is 15%) to obtain an intermediate annealed plate with an average grain size of 30μm.

[0066] (4) The intermediate annealed plate is preheated at 90°C, and then the second stage of cold rolling is carried out. The total reduction rate is controlled at 85% to obtain a secondary cold-rolled plate with a thickness of 0.15 mm.

[0067] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen content of 15%), with a dew point of -32℃, an annealing soaking temperature of 920℃, a holding time of 2 minutes, and a strip tension of 1.8 N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.8 N / mm. 2 .

[0068] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0069] Example 2

[0070] A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy specifically includes the following steps:

[0071] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.15%, Al: 0.67%, Mn: 0.41%, Cr: 0.42%, C: 0.0012%, S: 0.0010%, O: 0.0012%, N: 0.0013%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 130 mm.

[0072] The continuously cast billet was heated to 1040℃ and held for 100 minutes, and then hot rolled. The initial rolling temperature was 983℃, the final rolling temperature was 894℃, and the coiling temperature was 745℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 5.0 mm.

[0073] The obtained hot-rolled plate is subjected to shot blasting and pickling. The pickling temperature is 70℃ and the pickling solution is hydrochloric acid with a mass concentration of 8%, resulting in a pickled plate.

[0074] (2) The pickled plate is preheated at 90°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 84% to obtain a cold-rolled plate with a thickness of 0.8 mm.

[0075] (3) Annealing is performed on the first cold-rolled plate. The temperature of the soaking zone is 750℃ and the soaking time is 4min. A hydrogen-nitrogen mixture is used as the protective gas (hydrogen gas fraction is 15%) to obtain an intermediate annealed plate with an average grain size of 22μm.

[0076] (4) The intermediate annealed plate is subjected to a second stage of cold rolling, and the total reduction rate is controlled at 87.5% to obtain a secondary cold-rolled plate with a thickness of 0.10 mm.

[0077] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen integral of 20%), with a dew point of -32℃, an annealing soaking zone temperature of 960℃, a holding time of 2min, and a strip tension of 1.5N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.5 N / mm. 2 .

[0078] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0079] Example 3

[0080] A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy specifically includes the following steps:

[0081] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.24%, Al: 0.78%, Mn: 0.37%, Cr: 0.51%, C: 0.0008%, S: 0.0010%, O: 0.0010%, N: 0.0009%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 120 mm.

[0082] The continuously cast billet was heated to 1000℃ and held for 120 minutes, and then hot rolled. The initial rolling temperature was 955℃, the final rolling temperature was 868℃, and the coiling temperature was 733℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 5.0 mm.

[0083] The obtained hot-rolled plate is subjected to shot blasting and pickling. The pickling temperature is 80℃ and the pickling solution is hydrochloric acid with a mass concentration of 9%, resulting in a pickled plate.

[0084] (2) The pickled plate is preheated at 93°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 85% to obtain a cold-rolled plate with a thickness of 0.75 mm.

[0085] (3) Anneal the cold-rolled plate in one step. The temperature of the soaking zone is 760℃ and the soaking time is 5min. A hydrogen-nitrogen mixture is used as the protective gas (hydrogen gas fraction is 15%) to obtain an intermediate annealed plate with an average grain size of 25μm.

[0086] (4) The intermediate annealed plate is subjected to a second stage of cold rolling, and the total reduction rate is controlled at 86.67% to obtain a secondary cold-rolled plate with a thickness of 0.10 mm.

[0087] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen content of 30%), with a dew point of -34℃, an annealing soaking temperature of 950℃, a holding time of 2min, and a strip tension of 1.5N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.5 N / mm. 2 .

[0088] The annealed strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished sheet. The magnetic anisotropy of the non-oriented silicon steel finished sheet is shown in Table 2, and the microstructure is as follows: Figure 2 As shown, the macroscopic texture is as follows Figure 3 As shown, the finished annealed plate exhibits a uniform, continuous, moderately strong γ-fiber recrystallization texture and relatively weak... Recrystallization texture.

[0089] Example 4

[0090] A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy specifically includes the following steps:

[0091] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.37%, Al: 0.59%, Mn: 0.36%, Cr: 0.83%, C: 0.0009%, S: 0.0011%, O: 0.0012%, N: 0.0010%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 125 mm.

[0092] The continuously cast billet was heated to 1020℃ and held for 110 minutes, and then hot rolled. The initial rolling temperature was 964℃, the final rolling temperature was 887℃, and the coiling temperature was 726℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 6.0 mm.

[0093] The obtained hot-rolled plate is subjected to shot blasting and pickling. The pickling temperature is 85℃ and the pickling solution is hydrochloric acid with a mass concentration of 10%, resulting in a pickled plate.

[0094] (2) The pickled plate is preheated at 95°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 80% to obtain a cold-rolled plate with a thickness of 1.2 mm.

[0095] (3) Anneal the cold-rolled plate in one step. The temperature of the soaking zone is 790℃ and the soaking time is 5min. A hydrogen-nitrogen mixture is used as the protective gas (hydrogen gas fraction is 15%) to obtain an intermediate annealed plate with an average grain size of 32μm.

[0096] (4) The intermediate annealed plate is preheated at 92°C, and then the second stage of cold rolling is carried out. The total reduction rate is controlled at 87.5% to obtain a secondary cold-rolled plate with a thickness of 0.15 mm.

[0097] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen integral of 15%), with a dew point of -35℃, an annealing soaking zone temperature of 990℃, a holding time of 2min, and a strip tension of 2N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 2 N / mm. 2 .

[0098] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0099] Example 5

[0100] A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy specifically includes the following steps:

[0101] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.41%, Al: 0.87%, Mn: 0.45%, Cr: 0.79%, C: 0.0009%, S: 0.0012%, O: 0.0011%, N: 0.0013%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 140 mm.

[0102] The continuously cast billet was heated to 1050℃ and held for 120 minutes, and then hot rolled. The initial rolling temperature was 971℃, the final rolling temperature was 885℃, and the coiling temperature was 724℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 6.4 mm.

[0103] The obtained hot-rolled plate is subjected to shot blasting and pickling. The pickling temperature is 85℃ and the pickling solution is hydrochloric acid with a mass concentration of 10%, resulting in a pickled plate.

[0104] (2) The pickled plate is preheated at 98°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 87.5% to obtain a cold-rolled plate with a thickness of 0.8 mm.

[0105] (3) Anneal the cold-rolled plate in one step. The temperature of the soaking zone is 750℃ and the soaking time is 3min. A hydrogen-nitrogen mixture is used as the protective gas (hydrogen gas integral is 20%) to obtain an intermediate annealed plate with an average grain size of 20μm.

[0106] (4) The intermediate annealed plate is subjected to a second stage of cold rolling, and the total reduction rate is controlled at 87.5% to obtain a secondary cold-rolled plate with a thickness of 0.10 mm.

[0107] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen integral of 15%), with a dew point of -32℃, an annealing soaking zone temperature of 950℃, a holding time of 1.5 min, and a strip tension of 1.5 N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.5 N / mm. 2 .

[0108] The annealed strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished sheet. The magnetic anisotropy of the non-oriented silicon steel finished sheet is shown in Table 2, and the microstructure is as follows: Figure 4 As shown, the macroscopic texture is as follows Figure 5 As shown, the finished annealed plate exhibits a uniform, continuous, moderately strong γ-fiber recrystallization texture and relatively weak... Recrystallization texture.

[0109] Example 6

[0110] A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy specifically includes the following steps:

[0111] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.55%, Al: 0.77%, Mn: 0.33%, Cr: 0.45%, C: 0.0008%, S: 0.0011%, O: 0.0012%, N: 0.0010%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 120 mm.

[0112] The continuously cast billet was heated to 1050℃ and held for 120 minutes, and then hot rolled. The initial rolling temperature was 971℃, the final rolling temperature was 885℃, and the coiling temperature was 724℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 6.25mm.

[0113] The obtained hot-rolled plate was subjected to shot blasting and pickling. The pickling temperature was 85℃ and the pickling solution was hydrochloric acid with a mass concentration of 11%, resulting in a pickled plate.

[0114] (2) The pickled plate is preheated at 100°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 81.6% to obtain a cold-rolled plate with a thickness of 1.15 mm.

[0115] (3) Annealing is performed on the first cold-rolled plate. The temperature of the soaking zone is 790℃ and the soaking time is 4min. A hydrogen-nitrogen mixture is used as the protective gas (hydrogen gas fraction is 20%) to obtain an intermediate annealed plate with an average grain size of 29μm.

[0116] (4) The intermediate annealed plate is preheated at 97°C, and then the second stage of cold rolling is carried out. The total reduction rate is controlled at 86.96% to obtain a secondary cold-rolled plate with a thickness of 0.15 mm.

[0117] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen integral of 20%), with a dew point of -35℃, an annealing soaking zone temperature of 1000℃, a holding time of 2min, and a strip tension of 2N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 2 N / mm. 2 .

[0118] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0119] Example 7

[0120] A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy specifically includes the following steps:

[0121] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.77%, Al: 0.89%, Mn: 0.38%, Cr: 0.82%, C: 0.0009%, S: 0.0010%, O: 0.0013%, N: 0.0012%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 150 mm.

[0122] The continuously cast billet was heated to 1050℃ and held for 120 minutes, and then hot rolled. The initial rolling temperature was 971℃, the final rolling temperature was 885℃, and the coiling temperature was 724℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 5.0 mm.

[0123] The obtained hot-rolled plate was subjected to shot blasting and pickling. The pickling temperature was 85℃ and the pickling solution was hydrochloric acid with a mass concentration of 12%, resulting in a pickled plate.

[0124] (2) The pickled plate is preheated at 100°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 84% to obtain a cold-rolled plate with a thickness of 0.8 mm.

[0125] (3) Annealing is performed on the first cold-rolled plate. The temperature of the soaking zone is 780℃ and the soaking time is 4min. A hydrogen-nitrogen mixture is used as the protective gas (hydrogen gas fraction is 20%) to obtain an intermediate annealed plate with an average grain size of 28μm.

[0126] (4) The intermediate annealed plate is subjected to a second stage of cold rolling, and the total reduction rate is controlled at 87.5% to obtain a secondary cold-rolled plate with a thickness of 0.10 mm.

[0127] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen content of 30%), with a dew point of -34℃, an annealing soaking temperature of 900℃, a holding time of 2min, and a strip tension of 1.5N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.5 N / mm. 2 .

[0128] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0129] Example 8

[0130] A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy specifically includes the following steps:

[0131] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.98%, Al: 0.94%, Mn: 0.44%, Cr: 0.77%, C: 0.0008%, S: 0.0012%, O: 0.0011%, N: 0.0011%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to produce a continuously cast billet with a thickness of 130 mm.

[0132] The continuously cast billet was heated to 1050℃ and held for 120 minutes, and then hot rolled. The initial rolling temperature was 971℃, the final rolling temperature was 885℃, and the coiling temperature was 724℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 5.0 mm.

[0133] The obtained hot-rolled plate was subjected to shot blasting and pickling. The pickling temperature was 85℃ and the pickling solution was hydrochloric acid with a mass concentration of 12%, resulting in a pickled plate.

[0134] (2) The pickled plate is preheated at 95°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 85% to obtain a cold-rolled plate with a thickness of 0.75 mm.

[0135] (3) Annealing is performed on the first cold-rolled plate. The temperature of the soaking zone is 780℃ and the soaking time is 4min. A hydrogen-nitrogen mixture is used as the protective gas (hydrogen gas integral is 20%) to obtain an intermediate annealed plate with an average grain size of 27μm.

[0136] (4) The intermediate annealed plate is subjected to a second stage of cold rolling, and the total reduction rate is controlled at 86.67% to obtain a secondary cold-rolled plate with a thickness of 0.10 mm.

[0137] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen component of 20%), with a dew point of -33℃, an annealing soaking zone temperature of 950℃, a holding time of 2min, and a strip tension of 1.5N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.5 N / mm. 2 .

[0138] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0139] Comparative Example 1

[0140] A method for preparing non-oriented silicon steel specifically includes the following steps:

[0141] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.07%, Al: 0.57%, Mn: 0.33%, Cr: 0.45%, C: 0.0011%, S: 0.0011%, O: 0.0013%, N: 0.0012%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 135 mm.

[0142] The continuously cast billet was heated to 1020℃ and held for 100 minutes, and then hot rolled. The initial rolling temperature was 968℃, the final rolling temperature was 887℃, and the coiling temperature was 719℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 2.0 mm.

[0143] The hot-rolled plate is normalized with a soaking zone temperature of 950℃ and a soaking time of 7 minutes under a protective atmosphere of N2. Then it is shot-blasted and pickled. The pickling temperature is 70℃ and the pickling solution is hydrochloric acid with a mass concentration of 6%, resulting in a pickled plate.

[0144] (2) The pickled plate is preheated at 85°C and then cold rolled. The total reduction rate is controlled at 92.5% to obtain a cold-rolled plate with a thickness of 0.15 mm.

[0145] (3) The cold-rolled sheet is annealed using a hydrogen-nitrogen mixture as the protective gas (hydrogen content is 15%), with a dew point of -32℃, a soaking temperature of 920℃, a holding time of 2 minutes, and a strip tension of 1.8 N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.8 N / mm. 2 .

[0146] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0147] Comparative Example 2

[0148] A method for preparing non-oriented silicon steel specifically includes the following steps:

[0149] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.15%, Al: 0.67%, Mn: 0.41%, Cr: 0.42%, C: 0.0012%, S: 0.0010%, O: 0.0012%, N: 0.0013%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 130 mm.

[0150] The continuously cast billet was heated to 1040℃ and held for 100 minutes, and then hot rolled. The initial rolling temperature was 968℃, the final rolling temperature was 887℃, and the coiling temperature was 719℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 2.0 mm.

[0151] The hot-rolled plate is normalized with a soaking zone temperature of 950℃ and a soaking time of 7 minutes under a protective atmosphere of N2. Then it is shot-blasted and pickled. The pickling temperature is 70℃ and the pickling solution is hydrochloric acid with a mass concentration of 8%, resulting in a pickled plate.

[0152] (2) The pickled plate is preheated at 86°C and then cold rolled, with the total reduction rate controlled at 95%, to obtain a cold-rolled plate with a thickness of 0.10 mm.

[0153] (3) The cold-rolled sheet is annealed using a hydrogen-nitrogen mixture as the protective gas (hydrogen content is 20%), with a dew point of -32℃, a soaking temperature of 960℃, a holding time of 2 minutes, and a strip tension of 1.5 N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.5 N / mm. 2 .

[0154] The annealed strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished sheet. The magnetic anisotropy of the non-oriented silicon steel finished sheet is shown in Table 2, and the microstructure is as follows: Figure 6 As shown; macroscopic texture as Figure 7 As shown. A convex shape is formed in the finished annealed plate towards {111}. <112> Strong γ recrystallization texture aggregated at the component sites and towards {114} <481> Stronger aggregation at the component site Recrystallization texture.

[0155] Comparative Example 3

[0156] A method for preparing non-oriented silicon steel specifically includes the following steps:

[0157] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.24%, Al: 0.78%, Mn: 0.37%, Cr: 0.51%, C: 0.0008%, S: 0.0010%, O: 0.0010%, N: 0.0009%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 120 mm.

[0158] The continuously cast billet was heated to 1000℃ and held for 120 minutes, and then hot rolled. The initial rolling temperature was 956℃, the final rolling temperature was 865℃, and the coiling temperature was 735℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 2.0 mm.

[0159] The hot-rolled plate is normalized with a soaking zone temperature of 950℃ and a soaking time of 5 minutes under a protective atmosphere of N2. Then it is shot-blasted and pickled. The pickling temperature is 80℃ and the pickling solution is hydrochloric acid with a mass concentration of 9%, resulting in a pickled plate.

[0160] (2) The pickled plate is preheated at 85°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 75% to obtain a cold-rolled plate with a thickness of 0.5 mm.

[0161] (3) The cold-rolled plate is subjected to intermediate annealing. The temperature of the soaking zone is 950℃ and the soaking time is 4min. A mixture of hydrogen and nitrogen is used as the protective gas (hydrogen content is 15%) to obtain the intermediate annealed plate.

[0162] (4) The intermediate annealed plate is subjected to a second stage of cold rolling, and the total reduction rate is controlled at 80% to obtain a secondary cold-rolled plate with a thickness of 0.10 mm.

[0163] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen content of 30%), with a dew point of -35℃, an annealing soaking temperature of 950℃, a holding time of 2 minutes, and a strip tension of 1.5 N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.5 N / mm. 2 .

[0164] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0165] Comparative Example 4

[0166] A method for preparing non-oriented silicon steel specifically includes the following steps:

[0167] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.37%, Al: 0.59%, Mn: 0.36%, Cr: 0.83%, C: 0.0009%, S: 0.0011%, O: 0.0012%, N: 0.0010%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 125 mm.

[0168] The continuously cast billet was heated to 1020℃ and held for 110 minutes, and then hot rolled. The initial rolling temperature was 967℃, the final rolling temperature was 885℃, and the coiling temperature was 724℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 2.0 mm.

[0169] The hot-rolled plate is normalized with a soaking zone temperature of 950℃ and a soaking time of 5 minutes under a protective atmosphere of N2. Then it is shot-blasted and pickled. The pickling temperature is 85℃ and the pickling solution is hydrochloric acid with a mass concentration of 10%, resulting in a pickled plate.

[0170] (2) The pickled plate is preheated at 88°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 70% to obtain a cold-rolled plate with a thickness of 0.6 mm.

[0171] (3) The cold-rolled plate is subjected to intermediate annealing. The temperature of the soaking zone is 950℃ and the soaking time is 4min. A mixture of hydrogen and nitrogen is used as the protective gas (hydrogen content is 15%) to obtain the intermediate annealed plate.

[0172] (4) The intermediate annealed plate is subjected to a second stage of cold rolling, and the total reduction rate is controlled at 75% to obtain a secondary cold-rolled plate with a thickness of 0.15 mm.

[0173] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen integral of 15%), with a dew point of -35℃, an annealing soaking zone temperature of 990℃, a holding time of 2min, and a strip tension of 2.0N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 2.0 N / mm. 2 .

[0174] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0175] Comparative Example 5

[0176] A method for preparing non-oriented silicon steel specifically includes the following steps:

[0177] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.55%, Al: 0.77%, Mn: 0.33%, Cr: 0.45%, C: 0.0008%, S: 0.0011%, O: 0.0012%, N: 0.0010%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 120 mm.

[0178] The continuously cast billet was heated to 1050℃ and held for 120 minutes, and then hot rolled. The initial rolling temperature was 970℃, the final rolling temperature was 880℃, and the coiling temperature was 714℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 2.0 mm.

[0179] The hot-rolled plate is shot-blasted and pickled. The pickling temperature is 85℃ and the pickling solution is hydrochloric acid with a mass concentration of 11%, resulting in a pickled plate.

[0180] (2) The pickled plate is preheated at 95°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 70% to obtain a cold-rolled plate with a thickness of 0.6 mm.

[0181] (3) The cold-rolled plate is subjected to intermediate annealing. The temperature of the soaking zone is 940℃ and the soaking time is 5min. A mixture of hydrogen and nitrogen is used as the protective gas (hydrogen content is 20%) to obtain the intermediate annealed plate.

[0182] (4) The intermediate annealed plate is subjected to a second stage of cold rolling, and the total reduction rate is controlled at 75% to obtain a secondary cold-rolled plate with a thickness of 0.15 mm.

[0183] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen integral of 20%), with a dew point of -34℃, an annealing soaking zone temperature of 1000℃, a holding time of 2min, and a strip tension of 2N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 2 N / mm. 2 .

[0184] After annealing, the strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0185] Comparative Example 6

[0186] A method for preparing non-oriented silicon steel specifically includes the following steps:

[0187] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.77%, Al: 0.89%, Mn: 0.38%, Cr: 0.82%, C: 0.0009%, S: 0.0010%, O: 0.0013%, N: 0.0012%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 150 mm.

[0188] The continuously cast billet was heated to 1050℃ and held for 120 minutes, and then hot rolled. The initial rolling temperature was 965℃, the final rolling temperature was 870℃, and the coiling temperature was 720℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 1.6 mm.

[0189] The hot-rolled plate is shot-blasted and pickled. The pickling temperature is 85℃ and the pickling solution is hydrochloric acid with a mass concentration of 12%, resulting in a pickled plate.

[0190] (2) The pickled plate is preheated at 98°C, and then the first stage of cold rolling is carried out. The total reduction rate is controlled at 75% to obtain a cold-rolled plate with a thickness of 0.4 mm.

[0191] (3) The cold-rolled plate is subjected to intermediate annealing. The temperature of the soaking zone is 940℃ and the soaking time is 5min. A mixture of hydrogen and nitrogen is used as the protective gas (hydrogen content is 20%) to obtain the intermediate annealed plate.

[0192] (4) The intermediate annealed plate is subjected to a second stage of cold rolling, and the total reduction rate is controlled at 75% to obtain a secondary cold-rolled plate with a thickness of 0.10 mm.

[0193] (5) The secondary cold-rolled sheet is subjected to finished product annealing, using a hydrogen-nitrogen mixture as the protective gas (hydrogen content of 30%), with a dew point of -33℃, an annealing soaking temperature of 900℃, a holding time of 2 minutes, and a strip tension of 1.5 N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.5 N / mm. 2 .

[0194] The annealed strip is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished sheet. The magnetic anisotropy of the non-oriented silicon steel finished sheet is shown in Table 2, and the microstructure is as follows: Figure 8 As shown, the macroscopic texture is as follows Figure 9 As shown. A convex shape is formed in the finished annealed plate towards {111}. <112> Strong γ recrystallization texture aggregated at the component sites and towards {114} <481> Stronger aggregation at the component site Recrystallization texture.

[0195] Comparative Example 7

[0196] A method for preparing non-oriented silicon steel specifically includes the following steps:

[0197] (1) Smelting molten steel, the chemical composition of which, by mass percentage, includes Si: 3.94%, Al: 0.88%, Mn: 0.44%, C: 0.0008%, S: 0.0010%, O: 0.0010%, N: 0.009%, with the remainder being Fe and unavoidable impurities. The obtained molten steel is continuously cast to obtain a continuously cast billet with a thickness of 200 mm.

[0198] The continuously cast billet was heated to 1080℃ and held for 120 minutes, and then hot rolled. The initial rolling temperature was 970℃, the final rolling temperature was 882℃, and the coiling temperature was 735℃. After coiling, it was air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 2.0 mm.

[0199] The hot-rolled plate is normalized with a soaking zone temperature of 950℃ and a soaking time of 7 minutes under a protective atmosphere of N2. Then it is shot-blasted and pickled. The pickling temperature is 85℃ and the pickling solution is hydrochloric acid with a mass concentration of 12%, resulting in a pickled plate.

[0200] (2) The pickled plate is cold rolled, and the total reduction rate is controlled at 95% to obtain a cold-rolled plate with a thickness of 0.1 mm.

[0201] (3) The cold-rolled sheet is annealed using a hydrogen-nitrogen mixture as the protective gas (hydrogen content is 20%), with a dew point of -33℃, a soaking temperature of 1000℃, a holding time of 2 minutes, and a strip tension of 1.5 N / mm at the inlet of the continuous annealing furnace. 2 The export strip tension is 1.5 N / mm. 2 .

[0202] After annealing, the finished product is coated with an insulating layer, dried, and sintered to obtain a non-oriented silicon steel finished plate. The magnetic anisotropy of the non-oriented silicon steel finished plate is shown in Table 2.

[0203] The chemical compositions of the non-oriented silicon steel finished sheets of Examples 1-8 and Comparative Examples 1-7 are shown in Table 1.

[0204] Table 1. Chemical composition (wt%) of the non-oriented silicon steel finished sheets of Examples 1-8 and Comparative Examples 1-7:

[0205] .

[0206] The magnetic anisotropy of the non-oriented silicon steel finished plates of Examples 1-8 and Comparative Examples 1-7 is shown in Table 2.

[0207] Table 2. Magnetic anisotropy of the non-oriented silicon steel finished plates of Examples 1-8 and Comparative Examples 1-7:

[0208] .

[0209] As shown in Table 2, in Examples 1-8, the ultra-thin non-oriented silicon steel prepared by the technology of this invention all achieved a magnetic induction intensity B. 50 Anisotropy ≤ 0.5%, iron loss P 10 / 400 Anisotropy ≤ 4%, iron loss P 10 / 1000 Anisotropy ≤4%. Compared with products prepared by existing technologies and 0.5mm non-oriented silicon steel currently on the market with magnetic anisotropy of 8%~10%, this represents a significant technological advancement. For example... Figure 3 and Figure 5 As shown, in Examples 3 and 5, the present invention's technology resulted in a relatively uniform, continuous, and moderately strong γ-fiber recrystallization texture and a relatively weak... The recrystallization texture significantly reduces magnetic anisotropy. In Comparative Examples 1-6, the compositions used were the same as in the examples, but the preparation process was not the technology of this invention, and the magnetic anisotropy of the prepared ultrathin non-oriented silicon steel was significantly increased. Figure 7 and Figure 9 As shown, in Comparative Examples 2 and 6, the finished annealed plates were formed with {111} <112> Strong γ recrystallization texture aggregated at the component sites and towards {114} <481> Stronger aggregation at the component site The recrystallization texture leads to significant magnetic anisotropy in the material. In Comparative Example 7, strip breakage occurred during cold rolling, preventing product preparation. Therefore, as seen in Comparative Examples 1-7, when the manufacturing process is outside the scope of this invention, the magnetic anisotropy of the product increases significantly, and strip breakage during cold rolling occurs in high-alloy systems. The magnetic anisotropy in the embodiments of this invention is significantly better than that in the comparative examples.

Claims

1. A method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy, characterized in that, Specifically, the following steps are included: (1) Steel is smelted and continuously cast ingots are made according to the composition of Si mass percentage ≥ 3.0%. The continuously cast ingots are heated and hot rolled. The resulting hot rolled plates are shot blasted and pickled to obtain pickled plates. (2) The pickled plate is cold rolled, and the total cold rolling reduction rate is controlled to be ≥80% to obtain a single cold rolled plate; (3) Anneal the cold-rolled plate in one step, with the temperature of the soaking zone being 750℃~800℃ and the holding time in the soaking zone being 3min~5min, to obtain an intermediate annealed plate with an average grain size ≤40μm; (4) The intermediate annealed plate is cold rolled, and the total cold rolling reduction rate is controlled to be ≥85% to obtain the secondary cold rolled plate; (5) The secondary cold-rolled sheet is annealed, then coated with an insulating layer, dried and sintered to obtain a non-oriented silicon steel finished sheet; The thickness of the ultra-thin non-oriented silicon steel finished plate with low magnetic anisotropy is 0.10mm~0.15mm, and the magnetic induction intensity B 50 Anisotropy ≤ 0.5%, iron loss P 10 / 400 Anisotropy ≤ 4%, iron loss P 10 / 1000 Anisotropy ≤ 4%.

2. The method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy according to claim 1, characterized in that, In step (1), the chemical composition of the molten steel, by mass percentage, includes Si: 3.0%~4.0%, Al: 0.5%~1.0%, Mn: 0.3%~0.5%, Cr: 0.4%~1.2%, C≤0.0015%, S≤0.0015%, O≤0.0015%, N≤0.0015%, with the remainder being Fe and unavoidable impurities.

3. The method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy according to claim 1, characterized in that, In step (1), the thickness of the continuous casting billet is 120mm~150mm; the continuous casting billet is heated to 1000℃~1050℃ and held for 90min~120min for hot rolling, the initial rolling temperature is 950℃~1000℃, the final rolling temperature is 860℃~910℃, the coiling temperature is 700℃~750℃, and after coiling, it is air-cooled to room temperature.

4. The method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy according to claim 1, characterized in that, In step (1), the pickling uses hydrochloric acid solution with a mass concentration of 5% to 12% and a pickling temperature of 65℃ to 85℃.

5. The method for preparing an ultrathin non-oriented silicon steel with low magnetic anisotropy according to claim 1, characterized in that, In step (2), the pickled plate is preheated before cold rolling, and the preheating temperature is 80℃~150℃.

6. The method for preparing ultrathin non-oriented silicon steel with low magnetic anisotropy according to claim 1, characterized in that, In step (3), the protective gas for the intermediate annealing of the cold-rolled plate is a mixture of hydrogen and nitrogen, with a hydrogen component of ≥15%.

7. The method for preparing an ultrathin non-oriented silicon steel with low magnetic anisotropy according to claim 1, characterized in that, In step (4), when the thickness of the intermediate annealing plate is ≥1.0mm, the intermediate annealing plate needs to be preheated before cold rolling, and the preheating temperature is 80℃~150℃; when the thickness of the intermediate annealing plate is <1.0mm, the intermediate annealing plate does not need to be preheated before cold rolling.

8. The method for preparing an ultrathin non-oriented silicon steel with low magnetic anisotropy according to claim 1, characterized in that, In step (5), the final product annealing soaking temperature is 900℃~1000℃, and the soaking time is 1min~2.5min; the dew point is controlled ≤-30℃; and the strip tension in the furnace is controlled ≤2N / mm. 2 The protective gas inside the furnace is a mixture of hydrogen and nitrogen, with hydrogen comprising ≥15%.

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