Ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors and its manufacturing method

Abstract

The invention discloses an ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors and a manufacturing method thereof, belonging to the technical field of non-oriented silicon steel manufacturing. The invention comprises the following steps: smelting molten steel according to the components: Si 2.8-3.8%, Als 0.2-1.0%, Mn 0.1-0.6%, Cr 0.4-2.5%, Mo 0.02-0.3%, Sn≤0.15%, Sb≤0.15%, C≤0.0020%, S≤0.002%, N≤0.0007%, O<0.0006%, satisfying 0.50%≤[Cr]+3.3×[Mo]≤3.0% and [Sn]+[Sb]≤0.16%, and the rest being Fe and unavoidable impurities; and the steel is manufactured through continuous casting, heating, hot rolling, coiling, normalizing treatment, pickling, primary cold rolling, intermediate annealing, secondary cold rolling, continuous annealing and insulating layer coating, and the steel has excellent magnetic properties and corrosion resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-oriented silicon steel manufacturing, and particularly relates to an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors and a manufacturing method thereof. Background Art

[0002] Non-oriented silicon steel is a type of iron-silicon alloy with a silicon content of 0.3 - 6.5%, and is an important metal functional material in the fields of electric power, electronics, and military industry. Its working environment is in a rotating magnetic field, and the iron cores of motors and generators mostly use non-oriented silicon steel as the core material. With the sharp increase in the demand for portable and high-power density energy conversion devices in the fields of aerospace, national defense security, production, and daily life, the characteristics of high speed, small size, and high power density make high-speed motors more adaptable to the special requirements of modern high-end equipment. The speed of high-speed motors exceeds 10,000 r / min. As the driving motor speed increases and the magnetic field frequency increases, the energy loss (i.e., iron loss) generated by the silicon steel sheet increases. Therefore, it is required that the non-oriented silicon steel has low iron loss at high frequencies. The iron loss of non-oriented silicon steel at high frequencies is mainly eddy current loss, and the eddy current loss is proportional to the square of the working frequency or the thickness of the steel sheet. Therefore, reducing the thickness of the silicon steel sheet is an important means to reduce iron loss. At the same time, in order to ensure the strong driving force of the motor, it is also necessary to increase the magnetic induction intensity of the silicon steel sheet as much as possible. It is of great significance to develop a high-performance extremely thin cold-rolled non-oriented silicon steel with a thickness not exceeding 0.15 mm.

[0003] However, the preparation of extremely thin cold-rolled non-oriented silicon steel often requires severe cold rolling deformation, which destroys the favorable {001}<0vw>texture of the initial cast columnar crystal, resulting in serious deterioration of the texture, low magnetic induction intensity, and high iron loss, making it difficult to meet the requirements of high-speed motors. Currently, extremely thin non-oriented silicon steel with excellent magnetic properties has become one of the research hotspots in the field of non-oriented silicon steel. In addition, for motors in some scenarios such as strong corrosion environments like the ocean, coastal areas, islands, chemical industry, oil and gas, etc., harsh requirements are also put forward for the corrosion resistance of the silicon steel sheet. Currently, at home and abroad, only by coating a few micrometers of coating on the steel sheet surface can the corrosion resistance be ensured. Non-oriented silicon steel or the motor iron core made of it often corrodes during transportation, storage, or long-term use, which is particularly prominent under harsh environmental conditions such as high temperature, high humidity, and strong corrosion in the ocean, chemical industry, oil and gas, etc. The surface and cross-section of the non-oriented silicon steel sheet or the motor iron core made of it are severely corroded chemically or electrochemically, which not only deteriorates the magnetic properties of the non-oriented silicon steel, but also seriously affects the service life and safety of the motor. Currently, there are no high-corrosion-resistant non-oriented silicon steel products at home and abroad. Therefore, it is necessary to develop an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors and a manufacturing method thereof.

[0004] Patent CN112538592B discloses a non-oriented silicon steel for high-speed motors with a frequency ≥ 10,000 Hz and its production method. The chemical components and weight percentages are as follows: C ≤ 0.003%, Si 2.8 - 4.0%, Mn 0.05 - 1.0%, P ≤ 0.0015%, N ≤ 0.0008%, Al 0.75 - 1.5%, S ≤ 0.0009%, Sb 0.001 - 0.1%, Sn 0.001 - 0.1%, and it satisfies that Sb + Sn is within 0.0075 - 0.1%. The rest is Fe and inevitable impurities. The thickness of the steel plate is 0.02 - 0.15 mm, P 1 / 10000 does not exceed 15.5 W / kg, P 10 / 400 does not exceed 9.5 W / kg, magnetic induction intensity B 50 is not less than 1.6 T. It adopts a production technical route of hot rolling, normalizing, pickling, three times of cold rolling and three times of annealing, with a long process flow and high production and manufacturing costs.

[0005] Patent CN114058961B discloses a non-oriented silicon steel strip with a thickness ≤ 0.15 mm and its production method. The chemical components and weight percentages are as follows: Si 2.0 - 6.5%, Mn 0.13 - 0.40%, S ≤ 0.020%, P ≤ 0.020%, Als 0.15 - 0.9%, C ≤ 0.010%. After smelting and casting into billets, it is hot rolled, cold rolled, degreased, bright bell annealing, and coated with an insulating layer. Iron loss P 10 / 400 ≤ 13 W / kg, magnetic induction intensity B 50 ≥ 1.5 T. However, the magnetic properties at higher working frequencies are not mentioned, and due to the use of bell annealing, the production efficiency is low and the production cost is high.

[0006] Patent CN115198198B discloses a non-oriented silicon steel for high-speed motors and its preparation method. The chemical components and weight percentages are as follows: C ≤ 0.0020%, S ≤ 0.0010%, N ≤ 0.0030%, Si 3.0 - 3.4%, Al 0.80 - 1.0%, Mn 0.2 - 0.4%, P ≤ 0.01%, Sn + Sb ≤ 0.004%, Nb ≤ 0.005%, V ≤ 0.005%, Ti ≤ 0.005%, Mo ≤ 0.005%, Cr ≤ 0.05%, Ni ≤ 0.05%, Cu ≤ 0.05%, 0 < C + S + N ≤ 0.0050%, and the rest is Fe and inevitable inclusion elements. The preparation process includes smelting, continuous casting, heating, hot rolling, normalizing, pickling, cold rolling, annealing and coating. The thickness of the non-oriented silicon steel finished product is 0.20 - 0.30 mm, the yield strength ≥ 550 MPa, magnetic induction B 50 ≥ 1.65 T, the high-frequency iron loss P at a thickness of 0.30 mm 10 / 1000 ≤ 45 W / kg, the high-frequency iron loss P at a thickness of 0.25 mm10 / 1000 ≤40 W / kg, high-frequency iron loss P at a thickness of 0.20 mm 10 / 1000 ≤35 W / kg, but the corrosion resistance is not involved.

[0007] The above patent does not involve the corrosion resistance of ultra-thin non-oriented silicon steel. To meet the harsh requirements of high-speed motors in terms of long-term service, safety, high efficiency, and energy conservation in strongly corrosive environments such as the ocean, coastal areas, islands and reefs, chemical industry, oil and gas, etc., there is an urgent need to develop an ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors and its manufacturing method. Summary of the Invention

[0008] To meet the requirements of special high-speed motors for non-oriented silicon steel sheets with low iron loss, high magnetic induction intensity, and excellent corrosion resistance, and to solve the existing technical problems at the present stage, the present invention provides an ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors and its manufacturing method.

[0009] An ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, with the following elemental components by mass percentage:

[0010] Si 2.8 - 3.8%, Als 0.2 - 1.0%, Mn 0.1 - 0.6%, Cr 0.4 - 2.5%, Mo 0.02 - 0.3%, Sn ≤ 0.15%, Sb ≤ 0.15%, C ≤ 0.0020%, S ≤ 0.002%, N ≤ 0.0007%, O < 0.0006%, and the rest is Fe and inevitable impurities;

[0011] The contents of Cr and Mo satisfy 0.50% ≤ [Cr] + 3.3 × [Mo] ≤ 3.0%;

[0012] The contents of Sn and Sb satisfy [Sn] + [Sb] ≤ 0.16%.

[0013] The thickness of the ultra-thin non-oriented silicon steel is 0.1 ± 0.005 mm, and its magnetic properties are: B 50 ≥1.62 T, P 10 / 400 ≤9.5 W / kg, P 10 / 1000 ≤30.0 W / kg.

[0014] The thickness of the ultra-thin non-oriented silicon steel is 0.15 ± 0.005 mm, and its magnetic properties are: B 50 ≥1.63 T, P 10 / 400 ≤11.0 W / kg, P 10 / 1000 ≤35.0 W / kg.

[0015] The self-corrosion potential of the ultra-thin non-oriented silicon steel is ≥ -0.5 V in a 3.5% NaCl aqueous solution at room temperature.

[0016] The manufacturing method of the ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for the above high-speed motor specifically includes the following steps:

[0017] (1) Continuous casting: Smelt molten steel according to the components, and then make a continuous casting billet with a thickness of 180 - 250 mm;

[0018] (2) Hot rolling: Heat the continuous casting billet obtained in step (1) to 1050 - 1170 °C and keep it warm for 1.5 - 2.5 h, then carry out hot rolling and coiling, and air-cool to room temperature to obtain a hot-rolled sheet;

[0019] (3) Normalizing treatment: After normalizing the hot-rolled sheet obtained in step (2) under the condition of nitrogen as the protective atmosphere, carry out shot blasting and pickling to obtain a pickled sheet;

[0020] (4) First cold rolling: Carry out first cold rolling on the pickled sheet obtained in step (3), and control the thickness of the obtained first cold-rolled sheet to be 0.3 - 0.6 mm;

[0021] (5) Intermediate annealing: Carry out intermediate annealing on the first cold-rolled sheet at a temperature of 950 - 1050 °C and keep it warm for 1 - 3 min;

[0022] (6) Second cold rolling: Carry out second cold rolling on the sheet processed in step (5), and control the thickness after rolling to be 0.1 ± 0.005 mm and 0.15 ± 0.005 mm respectively;

[0023] (7) Continuous annealing: Carry out continuous annealing on the cold-rolled sheet after second cold rolling at a temperature of 850 - 1000 °C, keep it warm for 1 - 3 min, and the dew point is below -30 °C;

[0024] (8) Apply an insulating layer, dry, and sinter in sequence to obtain a finished non-oriented silicon steel sheet.

[0025] Among them:

[0026] In the said step (2), the starting rolling temperature is 1000 - 1130 °C, the final rolling temperature is 800 - 890 °C; the coiling temperature is 500 - 680 °C, and the thickness of the hot-rolled sheet is 1.8 - 3.0 mm.

[0027] In the said step (3), the normalizing temperature is 850 - 1000 °C, and the holding time is 3 - 10 min.

[0028] In the said step (3), the acid used for pickling is hydrochloric acid with a mass concentration of 2 - 10%, and the pickling temperature is 70 - 90 °C.

[0029] In the said step (7), on the premise of ensuring good strip shape of the strip steel, reduce the strip steel tension in the furnace, and control it at 3 - 5 N / mm2 。

[0030] During the annealing process, in order to prevent the formation of chromium nitride on the surface of the steel plate, a mixed gas of hydrogen and nitrogen is used as the protective gas, and the volume fraction of hydrogen ≥ 5%.

[0031] The control principle of each alloying element and its mass percentage of non-oriented silicon steel in the present invention is as follows:

[0032] Si 2.8 - 3.8%, Als 0.2 - 1.0%: Both Si and Al are effective additive elements for increasing the resistivity, reducing iron loss, and increasing strength. However, as the contents of Si and Al increase, the rolling difficulty increases, edge cracking is likely to occur during the hot rolling process, and strip breakage is likely to occur during the cold rolling process; at the same time, as the contents of Si and Al increase, the magnetic induction of the steel plate decreases. In the present invention, the Si content is controlled at 2.8 - 3.8%, and the Als content is controlled at 0.20 - 1.0% to reduce the high-frequency iron loss and increase the material strength.

[0033] Mn 0.1 - 0.6%: Appropriate addition of Mn is beneficial to improving the magnetic properties of the steel plate and can also increase the strength of the steel plate. Mn can inhibit the hot brittleness caused by S, and it is easy to form coarse MnS precipitates with S, thereby reducing the iron loss of the steel plate. In the present invention, the Mn content is controlled at 0.1 - 0.6%. Since the S content in the present invention ≤ 0.0020%, the Mn / S is relatively high, which can promote the precipitation and growth of MnS and is beneficial to the magnetic properties.

[0034] Cr 0.4 - 2.5%: Cr is an alloying element for increasing the resistivity and improving the corrosion resistance. Increasing the Cr content helps to increase the resistivity, thereby reducing the iron loss and improving the corrosion resistance. However, if the Cr content is too high, on the one hand, a large amount of harmful precipitates such as chromium nitride and chromium carbide will be formed, deteriorating the iron loss; on the other hand, it will also cause serious lattice distortion and deteriorate the magnetic induction. Moreover, too high a Cr content will significantly increase the difficulty of removing the surface scale during pickling of the normalized steel plate. Therefore, in the present invention, the Cr content is controlled at 0.4 - 2.5%, and 0.50% ≤ [Cr] + 3.3 × [Mo] ≤ 3.0% is satisfied.

[0035] Mo 0.02 - 0.3%: Mo is an alloying element for improving the corrosion resistance. Increasing the Mo content helps to improve the corrosion resistance. However, if the Mo content is too high, on the one hand, a large amount of harmful precipitates such as molybdenum nitride and molybdenum carbide will be formed, deteriorating the iron loss; on the other hand, it will also cause serious lattice distortion and deteriorate the magnetic induction. Too high a Mo content will also increase the cost and significantly increase the difficulty of removing the surface scale during pickling of the normalized steel plate. Therefore, in the present invention, the Mo content is controlled at 0.02 - 0.3%, and 0.50% ≤ [Cr] + 3.3 × [Mo] ≤ 3.0% is satisfied.

[0036] Sn ≤ 0.15%, Sb ≤ 0.15%: Both Sn and Sb are grain boundary segregation elements. Adding Sn alone, Sb alone, or adding Sn and Sb in combination to non-oriented electrical steel aims to reduce the proportion of unfavorable {111} texture and improve the magnetic induction intensity through the segregation of Sn and Sb at grain boundaries. Due to the grain boundary segregation behavior of Sn and Sb, adding excessive amounts will cause embrittlement of the steel plate, easy breakage of the strip during cold rolling, and increased production difficulty. Therefore, both Sn and Sb are ≤ 0.15%, and [Sn] + [Sb] ≤ 0.16% is satisfied to ensure the rollability of the steel plate.

[0037] C ≤ 0.0020%: C is a harmful element, and its content should be as low as possible. On the one hand, C forms an interstitial solid solution with Fe, causing severe lattice distortion and deteriorating magnetic properties; on the other hand, C easily forms chromium carbide precipitates with Cr, pinning magnetic domains and thus leading to deterioration of magnetic properties. Therefore, in this invention, the C content is controlled at ≤ 0.0020%.

[0038] S ≤ 0.002%: S is a harmful element, and its content should be as low as possible. S easily combines with Mn to form manganese sulfide precipitates, increasing iron loss, coercivity, and reducing magnetic induction. Therefore, the S content is controlled at ≤ 0.002%.

[0039] N ≤ 0.0007%: N is a harmful element, and its content should be as low as possible. On the one hand, N forms an interstitial solid solution with Fe, causing severe lattice distortion and deteriorating magnetic properties; on the other hand, N easily forms chromium nitride precipitates with Cr, pinning magnetic domains and thus leading to deterioration of magnetic properties. Therefore, in this invention, the N content is controlled at ≤ 0.0007%.

[0040] O < 0.0006%: O is a harmful element, and its content should be as low as possible. O easily combines with Al and Si to form oxide inclusions, increasing iron loss, coercivity, and reducing magnetic induction. Therefore, the O content is controlled < 0.0006%.

[0041] The control principle of the process parameters in each process of this invention is as follows:

[0042] (1) In this invention, the hot rolling heating temperature is controlled at 1050 - 1170 °C and held for 1.5 - 2.5 h. The main reason is that below 1050 °C, the rolling pressure is large and it is difficult to roll to the target thickness; above 1170 °C, it is easy to cause the precipitation of nano-scale second-phase particles such as manganese sulfide, aluminum nitride, chromium carbide, and chromium nitride, which is unfavorable for the magnetic properties of the product; holding for 1.5 - 2.5 h, on the one hand, the slab should be burned through, and on the other hand, the burning loss should be minimized and the solid solution amount of second-phase particles such as manganese sulfide, aluminum nitride, chromium carbide, and chromium nitride should be controlled.

[0043] (2) In the present invention, the starting rolling temperature of hot rolling is controlled at 1000 - 1130 °C, and the finishing rolling temperature is at 800 - 890 °C. If the starting rolling temperature is lower than 1000 °C, the rolling pressure of the steel plate is too high and it is difficult to ensure the finishing rolling temperature; if the starting rolling temperature is higher than 1130 °C, the scale on the casting blank cannot be completely removed by high-pressure water. The relatively high finishing rolling temperature is to increase the content of recrystallized grains in the hot-rolled sheet, thereby weakening the hard-to-magnetize {111} <uvw>Texture and improve magnetic induction intensity.

[0044] (3) The hot rolling coiling temperature of the present invention is controlled at 500 - 680 °C. The main reason is that when coiling at a temperature higher than 680 °C, there is a dense oxide layer on the surface of the hot rolled sheet, which contains a large amount of Fe 3 O 4 , which is not conducive to pickling; when the temperature is lower than 500 °C, there are few recrystallized grains in the middle of the strip, and the {001}<0vw> easy magnetization texture is weak, deteriorating the magnetic properties.

[0045] (4) The normalizing temperature of the present invention is controlled at 850 - 1000 °C, the holding time is 3 - 10 min, and the protective atmosphere is nitrogen. The purpose is to improve the tissue uniformity and grain size, improve the texture type, and increase the strength of the favorable texture. When the temperature is lower than 850 °C or the holding time is less than 3 min, the purpose of recrystallized tissue uniformity and grain enlargement cannot be achieved; when the temperature is higher than 1000 °C or the holding time is longer than 10 min, it will cause some grains to be abnormally coarse, reduce the rollability, and cause energy waste.

[0046] (5) The pickling temperature of the present invention is 70 - 90 °C, and the mass concentration of hydrochloric acid is 2 - 10%. The purpose is to remove the scale on the surface of the strip after normalizing and improve the surface quality of the strip. When the pickling temperature is higher than 90 °C, the volatilization and consumption of hydrochloric acid will be accelerated; when the temperature is lower than 70 °C, the pickling effect is not good. When the mass concentration of hydrochloric acid is lower than 2%, the strip surface is under-pickled and the scale is not completely removed; when the mass concentration of hydrochloric acid is higher than 10%, the strip surface is over-pickled and the strip surface is corroded, affecting the rolling stability.

[0047] (6) The thickness of the first cold rolled sheet of the present invention is controlled at 0.3 - 0.6 mm. The purpose is to ensure that the reduction rate of the second cold rolling is greater than 50%, increase the cold rolling deformation energy storage, and the recrystallization and grain growth occur sufficiently during the continuous annealing process, thereby enhancing the {001}<0vw> texture favorable for magnetic properties and weakening the {111} <uvw>Texture

[0048] (7) The present invention controls the annealing temperature during the intermediate process of two cold rolling passes to be 950 - 1050 °C, and the holding time is 1 - 3 min. The purpose is to obtain a coarser grain structure. The coarser grains are prone to form a large number of intragranular shear bands during the subsequent cold rolling process, which is beneficial to increasing the {001}<0vw> texture favorable for magnetic properties during the final annealing process and improving the magnetic properties. A mixed gas of hydrogen and nitrogen is used as the protective gas, and the volume fraction of hydrogen is ≥ 5%, which can prevent the formation of chromium nitride on the strip surface, reduce iron loss, and improve magnetic properties.

[0049] (8) For the final continuous annealing process of the present invention, the annealing temperature is 850 - 1000 °C, and the holding time is 1 - 3 min. One is to obtain a larger recrystallized grain structure and reduce iron loss; the other is to prevent the oxidation of the strip surface by controlling the dew point below - 30 °C, thereby improving the magnetic properties. A mixed gas of hydrogen and nitrogen is used as the protective gas, and the volume fraction of hydrogen is ≥ 5%, which can prevent the formation of chromium nitride on the strip surface, reduce iron loss, and improve magnetic properties. The strip tension in the continuous annealing furnace is controlled at 3 - 5 N / mm 2 , one is to ensure good strip shape, the other is to reduce the internal stress of the strip, reduce iron loss, and improve magnetic properties.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] Through systematic control of the chemical composition of ultra-thin non-oriented silicon steel, hot rolling, normalizing treatment, two cold rolling processes, intermediate annealing process, and final annealing process, the present invention obtains excellent magnetic properties, namely, higher magnetic induction intensity and lower high-frequency iron loss, based on larger recrystallized grains and favorable recrystallized texture. Moreover, excellent corrosion resistance is obtained, which can meet the requirements of high-speed motors for the magnetic properties and corrosion resistance of non-oriented silicon steel in strongly corrosive environments such as marine, coastal, island reef, chemical industry, oil and gas, etc. Description of the Drawings

[0052] Figure 1 The manufacturing process flow chart of ultra-thin non-oriented silicon steel in the present invention;

[0053] Figure 2 The microstructural and texture diagrams of the finished plate prepared in Example 1 of the present invention. Among them, Fig. (a) is the microstructural diagram, and Fig. (b) is the texture diagram;

[0054] Figure 3 The polarization curve of the finished plate prepared in Example 1 of the present invention;

[0055] Figure 4 The microstructural and texture diagrams of the finished plate prepared in Example 2 of the present invention. Among them, Fig. (a) is the microstructural diagram, and Fig. (b) is the texture diagram;

[0056] Figure 5 The microstructure and texture map of the finished plate prepared in Comparative Example 1 of the present invention, where Figure (a) is the microstructure diagram and Figure (b) is the texture diagram;

[0057] Figure 6 The polarization curve of the finished plate prepared in Comparative Example 1 of the present invention;

[0058] Figure 7 The microstructure and texture map of the finished plate prepared in Comparative Example 2 of the present invention, where Figure (a) is the microstructure diagram and Figure (b) is the texture diagram. Detailed implementation manners

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, rather than all, of the embodiments of the present application. The following are the preferred embodiments of the present invention.

[0060] The equipment model used for observing the metallographic structure in the present invention is a Leica metallurgical microscope. The equipment model used for texture detection in the present invention is a Bruker D8 Discover X-ray diffractometer. The equipment model used for corrosion resistance detection in the present invention is CorrTest (CS2350), using calomel as the main electrode, a platinum sheet as the auxiliary electrode, and an aqueous NaCl solution with a mass concentration of 3.5% as the electrolyte. The scanning speed during testing is 0.5 mV / s. The equipment model used for magnetic property detection in the present invention is a MATS-2010M silicon steel magnetic property measurement device. The sample size is 100 mm × 30 mm, and the magnetic induction intensity B 50 and iron loss P 10 / 400 、P 10 / 1000 are measured, and the average values are taken respectively. Among them, B 50 represents the magnetic induction intensity under a magnetic field of 5000 A / m, and P 10 / 400 represents the iron loss under an alternating magnetic field with a magnetic induction intensity of 1.0 T and 400 Hz, and P 10 / 1000 represents the iron loss under an alternating magnetic field with a magnetic induction intensity of 1.0 T and 1000 Hz.

[0061] The following are the examples and comparative examples of the present invention.

[0062] Example 1

[0063] A manufacturing method for an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, the process flow diagram of which is as Figure 1 shown, and specifically includes the following steps:

[0064] (1) Smelt molten steel, the components of which are by mass percentage: Si 3.3%, Als 0.6%, Mn 0.45%, Cr 1.82%, Mo 0.04%, Sn 0.05%, Sb 0.04%, C 0.0018%, S 0.0008%, N 0.0003%, O 0.0005%, and the rest is Fe and inevitable impurities. Subsequently, the molten steel is made into a continuous casting billet through a continuous casting machine, with a thickness of 230 mm;

[0065] (2) Heat the continuous casting billet obtained in step (1) to 1100 °C and hold for 1.8 h, then carry out hot rolling and coiling. The starting rolling temperature is 1050 °C, the final rolling temperature is 870 °C, the coiling temperature is 676 °C, and after coiling, it is air-cooled to room temperature to obtain a hot-rolled sheet with a thickness of 2.08 mm;

[0066] (3) Normalize the hot-rolled sheet obtained in step (2) under the condition of a nitrogen protective atmosphere. The normalizing temperature is 950 °C and the holding time is 7 min. Then, shot blasting and pickling are carried out. The pickling temperature is 89 °C and the mass concentration of hydrochloric acid is 7% to obtain a pickled sheet;

[0067] (4) Carry out one-pass cold rolling on the pickled sheet obtained in step (3), and control the thickness of the obtained one-pass cold-rolled sheet to be 0.5 mm;

[0068] (5) Carry out intermediate annealing on the one-pass cold-rolled sheet at a temperature of 1000 °C for a holding time of 3 min. In order to prevent the formation of chromium nitride on the steel plate surface, a hydrogen-nitrogen mixed gas is used as the protective gas, and the volume fraction of hydrogen is 10%;

[0069] (6) Carry out two-pass cold rolling on the sheet treated in step (5), and control the thickness after rolling to be 0.0998 mm;

[0070] (7) The cold-rolled sheet after two-pass cold rolling is continuously annealed at a temperature of 990 °C. A hydrogen-nitrogen mixed gas is used as the protective gas, the volume fraction of hydrogen is 10%, the holding time is 3 min, and the dew point is -37 °C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 4 N / mm 2 , and the strip tension at the outlet is controlled at 5 N / mm 2 ;

[0071] (8) Apply an insulating layer, dry, and sinter in sequence to obtain a finished non-oriented silicon steel sheet.

[0072] The microstructure and texture diagram of the obtained finished non-oriented silicon steel sheet are as shown in Figure 2 shown, and the polarization curve is as shown in Figure 3 shown. The magnetic properties are: magnetic induction intensity B 50 = 1.63 T, iron loss P 10 / 400 = 8.42 W / kg, iron loss P 10 / 1000 = 27.02 W / kg; in a 3.5% mass concentration NaCl aqueous solution at room temperature, the self-corrosion potential is -0.488 V.

[0073] Example 2

[0074] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0075] (1) Smelt molten steel, and its components by mass percentage are: Si 3.40%, Als 0.75%, Mn 0.35%, Cr 0.63%, Mo 0.1%, Sn 0.03%, Sb 0.05%, C 0.0012%, S 0.001%, N 0.0005%, O 0.0004%, and the rest are Fe and inevitable impurities. Subsequently, the molten steel is made into a continuous casting billet with a thickness of 220 mm by a continuous casting machine;

[0076] (2) Heat the continuous casting billet obtained in step (1) to 1120 °C and hold for 1.8 h, then perform hot rolling and coiling. The starting rolling temperature is 1065 °C, the final rolling temperature is 880 °C, the coiling temperature is 664 °C, and after coiling, it is air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 2.15 mm;

[0077] (3) Normalize the hot-rolled plate obtained in step (2) under the condition of a nitrogen protective atmosphere. The normalizing temperature is 950 °C and the holding time is 7 min. Then, shot blasting and pickling are carried out. The pickling temperature is 88 °C and the mass concentration of hydrochloric acid is 5% to obtain a pickled plate;

[0078] (4) Perform one-pass cold rolling on the pickled plate obtained in step (3), and control the thickness of the obtained one-pass cold-rolled plate to be 0.5 mm;

[0079] (5) Perform intermediate annealing on the one-pass cold-rolled plate at a temperature of 990 °C for a holding time of 3 min. In order to prevent the formation of chromium nitride on the steel plate surface, a hydrogen-nitrogen mixed gas is used as the protective gas, and the hydrogen volume fraction is 14%;

[0080] (6) Perform two-pass cold rolling on the plate treated in step (5), and control the thickness after rolling to be 0.0997 mm;

[0081] (7) The cold-rolled plate after two-pass cold rolling is continuously annealed at a temperature of 990 °C. A hydrogen-nitrogen mixed gas is used as the protective gas, the hydrogen volume fraction is 10%, the holding time is 2.5 min, and the dew point is -33 °C; on the premise of ensuring good strip shape, the strip tension at the entrance of the continuous annealing furnace is 3.5 N / mm 2 , the strip tension at the outlet is controlled at 4 N / mm 2 ;

[0082] (8) Coating, drying, and sintering the insulating layer are carried out in sequence to obtain the finished non-oriented silicon steel sheet.

[0083] The microstructure and texture diagram of the obtained finished non-oriented silicon steel sheet are as Figure 4 shown. The magnetic properties are: magnetic induction intensity B 50 = 1.65 T, iron loss P 10 / 400 = 8.65 W / kg, iron loss P 10 / 1000 = 28.05 W / kg; the self-corrosion potential is -0.491 V.

[0084] Example 3

[0085] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0086] (1) Smelting molten steel, and its components by mass percentage are: Si 3.02%, Als 0.53%, Mn 0.35%, Cr 0.43%, Mo 0.25%, Sn 0.05%, Sb 0.07%, C 0.0015%, S 0.0012%, N 0.0003%, O 0.0005%, and the rest are Fe and inevitable impurities. Subsequently, the molten steel is made into a continuous casting billet with a thickness of 230 mm by a continuous casting machine;

[0087] (2) Heating the continuous casting billet obtained in step (1) to 1080 °C and holding for 1.8 h, then performing hot rolling and coiling. The starting rolling temperature is 1035 °C, the final rolling temperature is 860 °C, the coiling temperature is 654 °C, and after coiling, it is air-cooled to room temperature to obtain a hot-rolled sheet with a thickness of 2.12 mm;

[0088] (3) Normalizing the hot-rolled sheet obtained in step (2) under the condition of a nitrogen protective atmosphere. The normalizing temperature is 950 °C, and the holding time is 7 min. Then, shot blasting and pickling are carried out. The pickling temperature is 85 °C, and the mass concentration of hydrochloric acid is 5% to obtain a pickled sheet;

[0089] (4) Performing a first cold rolling on the pickled sheet obtained in step (3), and controlling the thickness of the obtained first cold-rolled sheet to be 0.5 mm;

[0090] (5) Performing intermediate annealing on the first cold-rolled sheet at a temperature of 1020 °C, and the holding time is 2.5 min. In order to prevent the formation of chromium nitride on the steel sheet surface, a hydrogen-nitrogen mixed gas is used as the protective gas, and the volume fraction of hydrogen is 13%;

[0091] (6) The sheet processed in step (5) is subjected to secondary cold rolling, and the thickness after rolling is controlled to be 0.102 mm;

[0092] (7) The cold-rolled sheet after secondary cold rolling is continuously annealed at a temperature of 990 °C, using a mixed gas of hydrogen and nitrogen as the protective gas, with a hydrogen volume fraction of 15%, a holding time of 3 min, and a dew point of -38 °C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 3.5 N / mm 2 , and the strip tension at the outlet is controlled at 4 N / mm 2 ;

[0093] (8) Insulation layer coating, drying, and sintering are carried out in sequence to obtain a finished non-oriented silicon steel sheet.

[0094] The magnetic properties of the obtained finished non-oriented silicon steel sheet are: magnetic induction intensity B 50 = 1.67 T, iron loss P 10 / 400 = 8.91 W / kg, iron loss P 10 / 1000 = 28.79 W / kg; in a 3.5% mass concentration NaCl aqueous solution and at room temperature, the self-corrosion potential is -0.457 V.

[0095] Example 4

[0096] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0097] (1) Smelt molten steel, and its components by mass percentage are: Si 3.28%, Als 0.63%, Mn 0.39%, Cr 2.20%, Mo 0.1%, Sn 0.07%, Sb 0.07%, C 0.0014%, S 0.0013%, N 0.0004%, O 0.0004%, and the rest are Fe and unavoidable impurities. Subsequently, the molten steel is made into a continuous casting billet through a continuous casting machine, with a thickness of 240 mm;

[0098] (2) The continuous casting billet obtained in step (1) is heated to 1100 °C and held for 2 h, then hot rolled and coiled. The starting rolling temperature is 1070 °C, the final rolling temperature is 875 °C, the coiling temperature is 670 °C, and it is air-cooled to room temperature after coiling to obtain a hot-rolled sheet with a thickness of 2.23 mm;

[0099] (3) The hot-rolled sheet obtained in step (2) is normalized under the condition of a nitrogen protective atmosphere, with a normalizing temperature of 950 °C and a holding time of 7 min. Then, shot blasting and pickling are carried out, the pickling temperature is 88 °C, and the mass concentration of hydrochloric acid is 8% to obtain a pickled sheet;

[0100] (4) Cold roll the pickled sheet obtained in step (3) once, and control the thickness of the obtained cold-rolled sheet to be 0.5 mm;

[0101] (5) Anneal the cold-rolled sheet once at a temperature of 980 °C for a holding time of 3 min. To prevent the formation of chromium nitride on the steel surface, a hydrogen-nitrogen mixed gas is used as the protective gas, and the volume fraction of hydrogen is 17%;

[0102] (6) Cold roll the sheet treated in step (5) twice, and control the thickness after rolling to be 0.103 mm;

[0103] (7) Continuously anneal the cold-rolled sheet after double cold rolling at a temperature of 990 °C. A hydrogen-nitrogen mixed gas is used as the protective gas, the volume fraction of hydrogen is 15%, the holding time is 3 min, and the dew point is -37 °C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 3.5 N / mm 2 , and the strip tension at the outlet is controlled at 5 N / mm 2 ;

[0104] (8) Coat, dry, and sinter the insulating layer in sequence to obtain a finished non-oriented silicon steel sheet.

[0105] The magnetic properties of the obtained finished non-oriented silicon steel sheet are: magnetic induction intensity B 50 = 1.64 T, iron loss P 10 / 400 = 8.82 W / kg, iron loss P 10 / 1000 = 29.31 W / kg; in a 3.5% NaCl aqueous solution at room temperature, the self-corrosion potential is -0.435 V.

[0106] Example 5

[0107] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0108] (1) Smelt molten steel, and its components by mass percentage are: Si 3.30%, Als 0.65%, Mn 0.41%, Cr 1.20%, Mo 0.22%, Sn 0.06%, Sb 0.07%, C 0.0017%, S 0.0006%, N 0.0003%, O 0.0003%, and the rest are Fe and inevitable impurities. Subsequently, make the molten steel into a continuous casting billet through a continuous casting machine, with a thickness of 210 mm;

[0109] (2) Heat the continuous casting billet obtained in step (1) to 1100 °C and hold for 2.1 h, then perform hot rolling and coiling. The starting rolling temperature is 1030 °C, the finishing rolling temperature is 865 °C, and the coiling temperature is 640 °C. After coiling, air cool to room temperature to obtain a hot rolled sheet with a thickness of 2.18 mm;

[0110] (3) Normalize the hot rolled sheet obtained in step (2) under the condition of nitrogen as the protective atmosphere. The normalizing temperature is 950 °C and the holding time is 7 min. Then, perform shot peening and pickling. The pickling temperature is 85 °C and the mass concentration of hydrochloric acid is 7% to obtain a pickled sheet;

[0111] (4) Perform first cold rolling on the pickled sheet obtained in step (3) and control the thickness of the obtained first cold rolled sheet to be 0.6 mm;

[0112] (5) Perform intermediate annealing on the first cold rolled sheet at a temperature of 1000 °C for a holding time of 2 min. In order to prevent the formation of chromium nitride on the steel plate surface, a hydrogen-nitrogen mixed gas is used as the protective gas, and the volume fraction of hydrogen is 15%;

[0113] (6) Perform second cold rolling on the sheet processed in step (5) and control the thickness after rolling to be 0.149 mm;

[0114] (7) The cold rolled sheet after second cold rolling is continuously annealed at a temperature of 990 °C. A hydrogen-nitrogen mixed gas is used as the protective gas, the volume fraction of hydrogen is 18%, the holding time is 2 min, and the dew point is -36 °C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 4 N / mm 2 , and the strip tension at the outlet is controlled at 5 N / mm 2 ;

[0115] (8) Perform insulation layer coating, drying, and sintering in sequence to obtain an non-oriented silicon steel finished sheet.

[0116] The magnetic properties of the obtained non-oriented silicon steel finished sheet are: magnetic induction intensity B 50 = 1.68 T, iron loss P 10 / 400 = 9.75 W / kg, iron loss P 10 / 1000 = 31.35 W / kg; in a 3.5% mass concentration NaCl aqueous solution at room temperature, the self-corrosion potential is -0.472 V.

[0117] Example 6

[0118] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0119] (1) Smelt molten steel, the components of which are by mass percentage: Si 3.52%, Als 0.62%, Mn 0.37%, Cr 1.08%, Mo 0.25%, Sn 0.06%, Sb 0.03%, C 0.0015%, S 0.0006%, N 0.0006%, O 0.0003%, and the rest are Fe and inevitable impurities. Subsequently, the molten steel is made into continuous casting billets with a thickness of 230 mm by a continuous casting machine;

[0120] (2) Heat the continuous casting billets obtained in step (1) to 1100 °C and hold for 1.9 h, then carry out hot rolling and coiling. The starting rolling temperature is 1050 °C, the finishing rolling temperature is 868 °C, the coiling temperature is 656 °C, and after coiling, it is air-cooled to room temperature to obtain a hot-rolled sheet with a thickness of 2.11 mm;

[0121] (3) Normalize the hot-rolled sheet obtained in step (2) under the condition of a nitrogen protective atmosphere. The normalizing temperature is 950 °C and the holding time is 7 min. Then, shot blasting and pickling are carried out. The pickling temperature is 89 °C and the mass concentration of hydrochloric acid is 7% to obtain a pickled sheet;

[0122] (4) Carry out one-pass cold rolling on the pickled sheet obtained in step (3), and control the thickness of the obtained one-pass cold-rolled sheet to be 0.6 mm;

[0123] (5) Carry out intermediate annealing on the one-pass cold-rolled sheet at a temperature of 970 °C for a holding time of 3 min. In order to prevent the formation of chromium nitride on the steel plate surface, a hydrogen-nitrogen mixed gas is used as the protective gas, and the volume fraction of hydrogen is 15%;

[0124] (6) Carry out two-pass cold rolling on the sheet treated in step (5), and control the thickness after rolling to be 0.153 mm;

[0125] (7) The cold-rolled sheet after two-pass cold rolling is continuously annealed at a temperature of 990 °C. A hydrogen-nitrogen mixed gas is used as the protective gas, the volume fraction of hydrogen is 15%, the holding time is 3 min, and the dew point is -38 °C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 3.5 N / mm 2 , and the strip tension at the outlet is controlled at 4 N / mm 2 ;

[0126] (8) Coat the insulating layer, dry, and sinter in sequence to obtain an non-oriented silicon steel finished sheet.

[0127] The magnetic properties of the obtained non-oriented silicon steel finished sheet are: magnetic induction intensity B 50 = 1.66 T, iron loss P 10 / 400 = 9.35 W / kg, iron loss P 10 / 1000 = 30.77 W / kg; in a 3.5% mass concentration NaCl aqueous solution at room temperature, the self-corrosion potential is -0.463 V.

[0128] Example 7

[0129] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0130] (1) Smelt molten steel, and its components by mass percentage are: Si 3.58%, Als 0.72%, Mn 0.35%, Cr 1.58%, Mo 0.23%, Sn 0.05%, Sb 0.04%, C 0.0012%, S 0.0013%, N 0.0005%, O 0.0004%, and the rest are Fe and inevitable impurities. Subsequently, the molten steel is made into a continuous casting billet with a thickness of 230 mm through a continuous casting machine;

[0131] (2) Heat the continuous casting billet obtained in step (1) to 1100 °C and hold for 1.8 h, then perform hot rolling and coiling. The starting rolling temperature is 1050 °C, the final rolling temperature is 867 °C, the coiling temperature is 654 °C, and after coiling, it is air-cooled to room temperature to obtain a hot-rolled sheet with a thickness of 2.15 mm;

[0132] (3) Normalize the hot-rolled sheet obtained in step (2) under the condition of a nitrogen protective atmosphere. The normalizing temperature is 950 °C and the holding time is 7 min. Then, shot blasting and pickling are carried out. The pickling temperature is 89 °C and the mass concentration of hydrochloric acid is 8% to obtain a pickled sheet;

[0133] (4) Perform a first cold rolling on the pickled sheet obtained in step (3), and control the thickness of the obtained first cold-rolled sheet to be 0.55 mm;

[0134] (5) Perform intermediate annealing on the first cold-rolled sheet at a temperature of 1010 °C for a holding time of 3 min. In order to prevent the formation of chromium nitride on the steel plate surface, a hydrogen-nitrogen mixed gas is used as the protective gas, and the hydrogen volume fraction is 15%;

[0135] (6) Perform a second cold rolling on the sheet treated in step (5), and control the thickness after rolling to be 0.148 mm;

[0136] (7) The cold-rolled sheet after the second cold rolling is continuously annealed at a temperature of 990 °C. A hydrogen-nitrogen mixed gas is used as the protective gas, the hydrogen volume fraction is 17%, the holding time is 3 min, and the dew point is -38 °C; on the premise of ensuring good strip shape of the steel strip, the strip tension at the inlet of the continuous annealing furnace is 4 N / mm 2 , and the strip tension at the outlet is controlled at 5 N / mm 2 ;

[0137] (8) Coating, drying, and sintering the insulation layer are carried out in sequence to obtain a non-oriented silicon steel finished plate.

[0138] The magnetic properties of the obtained non-oriented silicon steel finished plate are as follows: magnetic induction intensity B 50 = 1.65 T, iron loss P 10 / 400 = 9.05 W / kg, iron loss P 10 / 1000 = 30.18 W / kg; in a 3.5% mass concentration NaCl aqueous solution and at room temperature, the self-corrosion potential is -0.487 V.

[0139] Comparative Example 1

[0140] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0141] (1) Smelting molten steel, the components of which are by mass percentage: Si 3.30%, Als 0.6%, Mn 0.45%, Cr 0.0018%, Sn 0.05%, Sb 0.04%, C 0.0028%, S 0.0008%, N 0.0008%, O 0.0007%, and the rest is Fe and inevitable impurities. Subsequently, the molten steel is made into a continuous casting billet with a thickness of 230 mm through a continuous casting machine;

[0142] (2) Heating the continuous casting billet obtained in step (1) to 1100 °C and holding for 1.8 h, then performing hot rolling and coiling. The starting rolling temperature is 1035 °C, the final rolling temperature is 870 °C, the coiling temperature is 680 °C, and after coiling, it is air-cooled to room temperature to obtain a hot-rolled plate with a thickness of 2.08 mm;

[0143] (3) Normalizing the hot-rolled plate obtained in step (2) under the condition of nitrogen as the protective atmosphere, the normalizing temperature is 950 °C, and the holding time is 7 min. Then, shot blasting and pickling are carried out. The pickling temperature is 88 °C, and the mass concentration of hydrochloric acid is 5% to obtain a pickled plate;

[0144] (4) Performing a first cold rolling on the pickled plate obtained in step (3), and controlling the thickness of the obtained first cold-rolled plate to be 0.101 mm;

[0145] (5) The cold-rolled plate after the first cold rolling is continuously annealed at a temperature of 950 °C, using a hydrogen-nitrogen mixed gas as the protective gas, the hydrogen volume fraction is 17%, the holding time is 3 min, and the dew point is -38 °C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 4 N / mm 2 , and the strip tension at the outlet is controlled at 5 N / mm 2 ;

[0146] (6) Coating, drying, and sintering the insulation layer are carried out in sequence to obtain a finished non-oriented silicon steel sheet.

[0147] The microstructure and texture diagram of the obtained finished non-oriented silicon steel sheet are as shown in Figure 5 and the polarization curve is as shown in Figure 6 . The magnetic properties are as follows: magnetic induction intensity B 50 = 1.55 T, iron loss P 10 / 400 = 10.42 W / kg, iron loss P 10 / 1000 = 32.02 W / kg; in a 3.5% mass concentration NaCl aqueous solution and at room temperature, the self-corrosion potential is -0.664 V.

[0148] Comparative Example 2

[0149] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0150] (1) Smelting molten steel, the components of which are by mass percentage: Si 3.24%, Als 0.52%, Mn 0.38%, Cr 1.20%, Sn 0.05%, Sb 0.04%, C 0.0030%, S 0.0012%, N 0.0012%, O 0.0017%, and the rest are Fe and inevitable impurities. Subsequently, the molten steel is made into a continuous casting billet with a thickness of 230 mm by a continuous casting machine;

[0151] (2) Heating the continuous casting billet obtained in step (1) to 1100 °C and holding for 2.2 h, then performing hot rolling and coiling. The starting rolling temperature is 1055 °C, the final rolling temperature is 878 °C, the coiling temperature is 674 °C, and after coiling, it is air-cooled to room temperature to obtain a hot-rolled sheet with a thickness of 2.15 mm;

[0152] (3) Normalizing the hot-rolled sheet obtained in step (2) under the condition of a nitrogen protective atmosphere, the normalizing temperature is 950 °C, and the holding time is 7 min. Then, shot blasting and pickling are carried out, the pickling temperature is 88 °C, and the mass concentration of hydrochloric acid is 5% to obtain a pickled sheet;

[0153] (4) Performing primary cold rolling on the pickled sheet obtained in step (3), and controlling the thickness of the obtained primary cold-rolled sheet to be 0.0998 mm;

[0154] (5) The cold-rolled sheet after primary cold rolling is continuously annealed at a temperature of 970 °C, using a hydrogen-nitrogen mixed gas as the protective gas, the hydrogen volume fraction is 17%, the holding time is 3 min, and the dew point is -38 °C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 4 N / mm 2 , and the strip tension at the outlet is controlled at 5 N / mm 2 ;

[0155] (6) Coating, drying, and sintering the insulating layer are carried out in sequence to obtain a finished non-oriented silicon steel sheet.

[0156] The microstructure and texture diagram of the obtained finished non-oriented silicon steel sheet are as Figure 7 shown. The magnetic properties are: magnetic induction intensity B 50 = 1.59 T, iron loss P 10 / 400 = 9.75 W / kg, iron loss P 10 / 1000 = 30.35 W / kg; in a 3.5% mass concentration NaCl aqueous solution and at room temperature, the self-corrosion potential is -0.551 V.

[0157] Comparative Example 3

[0158] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0159] (1) Smelting molten steel, the components of which are by mass percentage: Si 2.58%, Als 0.47%, Mn 0.35%, Cr 0.0013%, C 0.0033%, S 0.0011%, N 0.0009%, O 0.0012%, and the rest are Fe and inevitable impurities. Subsequently, the molten steel is made into a continuous casting billet through a continuous casting machine, with a thickness of 230 mm;

[0160] (2) Heating the continuous casting billet obtained in step (1) to 1100 °C and holding for 2.1 h, then performing hot rolling and coiling. The starting rolling temperature is 1050 °C, the final rolling temperature is 868 °C, the coiling temperature is 664 °C, and after coiling, it is air-cooled to room temperature to obtain a hot-rolled sheet with a thickness of 2.11 mm;

[0161] (3) Normalizing the hot-rolled sheet obtained in step (2) under the condition of nitrogen as the protective atmosphere, with a normalizing temperature of 950 °C and a holding time of 7 min. Then, shot blasting and pickling are carried out, the pickling temperature is 88 °C, and the mass concentration of hydrochloric acid is 5% to obtain a pickled sheet;

[0162] (4) Performing a first cold rolling on the pickled sheet obtained in step (3), controlling the thickness of the obtained first cold-rolled sheet to be 0.34 mm;

[0163] (5) Performing an intermediate annealing on the first cold-rolled sheet at a temperature of 970 °C for a holding time of 3 min. In order to prevent the formation of chromium nitride on the steel sheet surface, a hydrogen-nitrogen mixed gas is used as the protective gas, and the volume fraction of hydrogen is 15%;

[0164] (6) Performing a second cold rolling on the sheet treated in step (5), controlling the thickness after rolling to be 0.103 mm;

[0165] (7) The cold-rolled sheet after secondary cold rolling is continuously annealed at a temperature of 1050°C, using a mixed gas of hydrogen and nitrogen as the protective gas, with a hydrogen volume fraction of 15%, a holding time of 3 minutes, and a dew point of -38°C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 4 N / mm 2 , and the strip tension at the outlet is controlled at 6 N / mm 2 ;

[0166] (8) Coating, drying, and sintering are carried out in sequence to obtain the finished non-oriented silicon steel sheet.

[0167] The magnetic properties of the obtained finished non-oriented silicon steel sheet are: magnetic induction intensity B 50 = 1.72 T, iron loss P 10 / 400 = 12.11 W / kg, iron loss P 10 / 1000 = 35.75 W / kg; in a 3.5% mass concentration NaCl aqueous solution and at room temperature, the self-corrosion potential is -0.667 V.

[0168] Comparative Example 4

[0169] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0170] (1) Smelt molten steel, and its components are by mass percentage: Si 3.28%, Als 0.63%, Mn 0.39%, Cr 2.20%, Mo 0.1%, Sn 0.07%, C 0.0014%, S 0.0013%, N 0.0004%, O 0.0008%, and the rest is Fe and inevitable impurities. Subsequently, the molten steel is made into a continuous casting billet through a continuous casting machine, with a thickness of 240 mm;

[0171] (2) Heat the continuous casting billet obtained in step (1) to 1100°C and hold for 2.2 h, then carry out hot rolling and coiling. The starting rolling temperature is 1040°C, the final rolling temperature is 887°C, the coiling temperature is 687°C, and after coiling, it is air-cooled to room temperature to obtain a hot-rolled sheet with a thickness of 2.23 mm;

[0172] (3) Normalize the hot-rolled sheet obtained in step (2) under the condition of nitrogen as the protective atmosphere, with a normalizing temperature of 950°C and a holding time of 7 minutes. Then, shot blasting and pickling are carried out, the pickling temperature is 88°C, and the mass concentration of hydrochloric acid is 8% to obtain a pickled sheet;

[0173] (4) Carry out primary cold rolling on the pickled sheet obtained in step (3), and control the thickness of the obtained primary cold-rolled sheet to be 1.14 mm;

[0174] (5) The primary cold-rolled sheet is subjected to intermediate annealing at a temperature of 970 °C for a holding time of 3 min. To prevent the formation of chromium nitride on the steel sheet surface, a hydrogen-nitrogen mixed gas is used as the protective gas, and the hydrogen volume fraction is 17%;

[0175] (6) The sheet treated in step (5) is subjected to secondary cold rolling, and the thickness after rolling is controlled to be 0.102 mm;

[0176] (7) The cold-rolled sheet after secondary cold rolling is subjected to continuous annealing at a temperature of 950 °C. A hydrogen-nitrogen mixed gas is used as the protective gas, the hydrogen volume fraction is 15%, the holding time is 3 min, and the dew point is -37 °C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 4 N / mm 2 , and the strip tension at the outlet is controlled at 5 N / mm 2 ;

[0177] (8) Insulation layer coating, drying, and sintering are carried out in sequence to obtain a finished non-oriented silicon steel sheet.

[0178] The magnetic properties of the obtained finished non-oriented silicon steel sheet are: magnetic induction intensity B 50 = 1.60 T, iron loss P 10 / 400 = 9.62 W / kg, iron loss P 10 / 1000 = 31.81 W / kg; in a 3.5% mass concentration NaCl aqueous solution at room temperature, the self-corrosion potential is -0.483 V.

[0179] Comparative Example 5

[0180] A manufacturing method of an extremely thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, specifically including the following steps:

[0181] (1) Molten steel is smelted, and its components by mass percentage are: Si 3.30%, Als 0.65%, Mn 0.41%, Cr 1.20%, Mo 0.22%, Sn 0.06%, Sb 0.01%, C 0.003%, S 0.0006%, N 0.0005%, O 0.00098%, and the rest are Fe and inevitable impurities. Subsequently, the molten steel is made into a continuous casting billet through a continuous casting machine, with a thickness of 230 mm;

[0182] (2) The continuous casting billet obtained in step (1) is heated to 1100 °C and held for 2.2 h, then hot rolled and coiled. The starting rolling temperature is 1045 °C, the final rolling temperature is 862 °C, the coiling temperature is 647 °C, and it is air-cooled to room temperature after coiling to obtain a hot-rolled sheet with a thickness of 2.18 mm;

[0183] (3) Normalize the hot-rolled sheet obtained in step (2) under the condition of nitrogen as the protective atmosphere, with a normalizing temperature of 950 °C and a holding time of 7 min. Then, shot peening and pickling are carried out, with a pickling temperature of 85 °C and a mass concentration of hydrochloric acid of 7%, to obtain a pickled sheet;

[0184] (4) Carry out a first cold rolling on the pickled sheet obtained in step (3), and control the thickness of the obtained first cold-rolled sheet to be 0.152 mm;

[0185] (5) The cold-rolled sheet after the first cold rolling is continuously annealed at a temperature of 1050 °C, using a hydrogen-nitrogen mixed gas as the protective gas, with a hydrogen volume fraction of 15%, a holding time of 3 min, and a dew point of -36 °C; on the premise of ensuring good strip shape, the strip tension at the inlet of the continuous annealing furnace is 4 N / mm 2 , and the strip tension at the outlet is controlled at 5 N / mm 2 ;

[0186] (6) Apply an insulating layer, dry, and sinter in sequence to obtain a finished non-oriented silicon steel sheet.

[0187] The magnetic properties of the obtained finished non-oriented silicon steel sheet are: magnetic induction intensity B 50 = 1.61 T, iron loss P 10 / 400 = 11.75 W / kg, iron loss P 10 / 1000 = 35.35 W / kg; in a 3.5% mass concentration NaCl aqueous solution and at room temperature, the self-corrosion potential is -0.585 V.

[0188] It can be seen from the comparative examples that when the alloy content or the preparation process is not within the scope of the present patent design, the magnetic properties and corrosion resistance of the product both deteriorate significantly, and the properties in the examples of the present invention are all significantly better than those of the comparative examples.< / uvw> < / uvw>

Claims

1. A method for manufacturing ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors, characterized in that: The specific steps include: (1) Continuous casting: Molten steel is smelted according to its composition and then made into continuous casting billets with a thickness of 180 to 250 mm; (2) hot rolling: heating the continuous casting slab obtained in step (1) to 1050-1170° C. and keeping the temperature for 1.5-2.5 h, then hot rolling and coiling, and air cooling to room temperature to obtain a hot-rolled plate; The starting rolling temperature is 1000-1130°C, the final rolling temperature is 800-890°C; the coiling temperature is 500-680°C, and the hot-rolled plate thickness is 1.8-3.0 mm; (3) Normalizing treatment: normalizing the hot-rolled sheet obtained in step (2) under the condition of nitrogen as a protective atmosphere, and then performing shot blasting and pickling to obtain a pickled sheet; The normalizing temperature is 850-1000°C, and the holding time is 3-10 minutes; (4) primary cold rolling: subjecting the pickled sheet obtained in step (3) to a primary cold rolling, wherein the thickness of the primary cold rolled sheet is controlled to be 0.3 to 0.6 mm; (5) Intermediate annealing: The primary cold-rolled sheet is subjected to intermediate annealing at a temperature of 950-1050°C for 1-3 minutes; (6) secondary cold rolling: the plate treated in step (5) is subjected to secondary cold rolling, and the thickness after rolling is controlled to be 0.1±0.005 mm and 0.15±0.005 mm respectively; (7) Continuous annealing: The cold-rolled sheet after secondary cold rolling is continuously annealed at a temperature of 850 to 1000°C, with a holding time of 1 to 3 minutes and a dew point below -30°C; (8) sequentially performing insulating layer coating, drying, and sintering to obtain a non-oriented silicon steel finished plate; The ultra-thin non-oriented silicon steel has the following elemental components in terms of mass percentage: Si 2.8~3.8%, Als 0.2~1.0%, Mn 0.1~0.6%, Cr 0.4~2.5%, Mo 0.02~0.3%, Sn≤0.15%, Sb≤0.15%, C≤0.0020%, S≤0.002%, N≤0.0007%, O<0.0006%, the rest is Fe and unavoidable impurities; The Cr and Mo contents satisfy 0.50%≤[Cr]+3.3×[Mo]≤3.0%; The Sn and Sb contents satisfy [Sn]+[Sb]≤0.16%.

2. The method for manufacturing ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors according to claim 1, characterized in that: The thickness of the ultra-thin non-oriented silicon steel is 0.1±0.005mm, and its magnetic properties are: B 50 ≥1.62T, P 10 / 400 ≤9.5W / kg, P 10 / 1000 ≤30.0W / kg.

3. The method for manufacturing ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors according to claim 1, characterized in that: The thickness of the ultra-thin non-oriented silicon steel is 0.15±0.005mm, and its magnetic properties are: B 50 ≥1.63T, P 10 / 400 ≤11.0W / kg, P 10 / 1000 ≤35.0W / kg.

4. The method for manufacturing ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors according to claim 1, characterized in that: The self-corrosion potential of the ultra-thin non-oriented silicon steel is ≥-0.5V under the conditions of a 3.5% mass concentration NaCl aqueous solution and room temperature.

5. The method for manufacturing ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors according to claim 1, characterized in that: In the step (3), the acid used for pickling is hydrochloric acid with a mass concentration of 2 to 10%, and the pickling temperature is 70 to 90°C.

6. The method for manufacturing ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors according to claim 1, characterized in that: In the step (7), under the premise of ensuring a good strip shape, the strip tension in the furnace is reduced and controlled to 3-5 N / mm 2 .

7. The method for manufacturing ultra-thin non-oriented silicon steel with excellent magnetic properties and corrosion resistance for high-speed motors according to claim 1, characterized in that: During the annealing process, in order to prevent the steel plate surface from nitriding to form chromium nitride, a hydrogen-nitrogen mixed gas is used as a protective gas, and the hydrogen gas volume fraction is ≥5%.

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