Non-oriented silicon steel for high-speed rotating motor and manufacturing method of non-oriented silicon steel

Abstract

The invention provides non-oriented silicon steel for a high-speed rotating motor and a manufacturing method of the non-oriented silicon steel. The non-oriented silicon steel comprises the following components in percentage by weight: less than or equal to 0.004% of C, 1.3-1.6% of Si, 0.2-0.5% of Mn, 0.15-0.30% of Als, 0.05-0.10% of P, less than or equal to 0.005% of S, less than or equal to 0.005% of N and the balance of Fe and inevitable impurities. The manufacturing method comprises the following steps: continuously casting a slab by molten steel; hot rolling; performing coiling; pickling; primary cold rolling; annealing is conducted; the thickness of the silicon steel product is 0.35 mm, the iron loss P1.5 / 50 ranges from 3.1 W / kg to 3.3 W / kg, the B5000 ranges from 1.72 T to 1.74 T, the yield strength ranges from 300 MPa to 330 MPa, the tensile strength ranges from 450 MPa to 480 MPa, and the hardness HV1 ranges from 140 to 150. In the molten steel continuous casting process, the thickness of a cast plate blank is 200-260 mm, the plate blank is directly loaded into a heating furnace to be heated, the temperature of the heating furnace is controlled to be 1100-1250 DEG C, and the heating and heat preservation time is not shorter than 210 min. In the hot rolling process, a hot rolled plate with the thickness of 2.0-2.3 mm is formed through seven passes of finish rolling, and the finish rolling temperature is required to be controlled to be 650-745 DEG C. The problem that the non-oriented silicon steel for the high-speed rotating motor cannot have high magnetic induction and high strength at the same time can be solved.

Description

Technical Field

[0001] This invention relates to the field of silicon steel manufacturing technology, and in particular to a non-oriented silicon steel for high-speed rotating motors and its manufacturing method. Background Technology

[0002] Silicon steel is mainly used in the production of various rotating electric machines, transformers, generators, etc. Non-oriented silicon steel, as a raw material for the production of various rotating electric machines, is an indispensable soft magnetic alloy material in the power, electronics, military, and transportation industries. With the development of non-oriented silicon steel, different application fields are not only selecting non-oriented silicon steel based on its magnetic properties, but also paying more attention to its mechanical properties. This is especially true in recent years with the rapid development of drive motors for new energy vehicles, where the design of these motors increasingly considers the mechanical properties of non-oriented silicon steel.

[0003] In the field of high-speed motors, the motors generate enormous centrifugal forces when rotating at high speeds. This necessitates that non-oriented silicon steel materials possess excellent magnetic properties such as low iron loss and high magnetic induction, while also exhibiting high strength to resist the centrifugal forces generated during motor rotation. To improve the strength of silicon steel materials, existing technologies primarily increase the percentage of alloying elements to enhance strength and reduce iron loss. These technologies are mainly used in new energy vehicle drive motors, with limited application in high-speed industrial motors.

[0004] For example, patent CN110004381A proposes a high-strength non-oriented silicon steel strip and its preparation method. The steel composition is: Al 0.5~1.0%, Si 3.0~3.5%, Mn 0.1~1.0%, Cu 1.0~2.0%, and the remaining amount of Fe and unavoidable impurities. This invention primarily improves strength by increasing the content of alloying elements, resulting in high costs. Patent CN107130169B proposes a high-strength cold-rolled non-oriented silicon steel and its manufacturing method, which improves strength by adding Cu and Ni elements and controlling the secondary cold rolling reduction, annealing, and aging processes. However, this method involves high Ni element prices, high preparation costs, complex processes, and low production efficiency. Patent CN108396233A proposes a high-strength non-oriented silicon steel and its manufacturing method, with the chemical composition by weight percentage as follows: Al: 0.1%~0.4%, Si: 1.3%~2.0%, Mn: 0.3%~0.7%, P: 0.02%~0.10%, Sb: 0.01%~0.07%, and the remainder being Fe and unavoidable impurities. Used in high-speed industrial motors, the produced silicon steel has a yield strength ≥270MPa and a tensile strength ≥410MPa. However, the silicon steel produced by this patent has poor magnetic properties and low iron loss. 1.5 / 50 Reaching 3.9W / Kg, while the magnetic induction B 5000 With a capacity of only around 1.70T, it is difficult to meet the magnetic performance requirements of high-performance, high-speed motors.

[0005] High-alloy non-oriented silicon steel is mainly used in new energy vehicle drive motors, military, and aerospace fields. The motor speed in these fields can reach 15,000 r / min, and the speed is generally above 3,000 r / min. In the field of high-speed rotating industrial motors below 10,000 r / min, although high-alloy non-oriented silicon steel has lower iron loss and higher strength, the high alloying elements reduce the magnetic induction, which cannot meet the high magnetic induction requirements of silicon steel for high-speed industrial motors. In addition, the low elongation and high hardness are not conducive to the stamping of stators and rotors of industrial motors.

[0006] Therefore, it is necessary to develop a new type of non-oriented silicon steel for high-speed rotating motors to solve the problem that non-oriented silicon steel for high-speed rotating motors cannot simultaneously possess both high magnetic induction and high strength. Summary of the Invention

[0007] The purpose of this invention is to provide a non-oriented silicon steel for high-speed rotating motors and its manufacturing method, so as to solve the problem that existing non-oriented silicon steel for high-speed rotating motors cannot simultaneously possess both high magnetic induction and high strength.

[0008] To solve the above-mentioned technical problems, the present invention provides a non-oriented silicon steel for high-speed rotating motors, comprising the following components and their weight percentages: C≤0.004%, Si: 1.3~1.6%, Mn: 0.2~0.5%, Als: 0.15~0.30%, P: 0.05~0.10%, S≤0.005%, N≤0.005%, with the remainder being Fe and unavoidable impurities.

[0009] The present invention also provides a method for manufacturing the above-mentioned non-oriented silicon steel for high-speed rotating motors, the method comprising: continuously casting molten steel into a slab; hot rolling; coiling; pickling; single cold rolling; annealing; and... Secondary cold rolling; wherein the silicon steel product has a thickness of 0.35mm and an iron loss P 1.5 / 50 At 3.1~3.3 W / kg, B 5000 The yield strength is between 1.72 and 1.74 T, the yield strength is between 300 and 330 MPa, the tensile strength is between 450 and 480 MPa, and the hardness HV1 is between 140 and 150.

[0010] Optionally, in the continuous steel casting process, the thickness of the cast slab is 200~260mm, and the slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1100~1250℃, and the heating and holding time is not less than 210min.

[0011] Optionally, in the hot rolling process, the hot-rolled plate is finished in 7 passes to a thickness of 2.0~2.3mm, and the final rolling temperature is required to be controlled at 650~745℃.

[0012] Optionally, in the winding process, the winding temperature is controlled at 550~600℃, and the winding is allowed to cool naturally to room temperature after winding.

[0013] Optionally, in the pickling process, the hot-rolled strip steel passes through a normalizing and pickling line, with the normalizing temperature controlled at 880~920℃ and the normalizing time at 2~4 minutes. After normalizing, the hot-rolled strip steel is first cooled to 600~700℃ at 5~10℃ / s, and then cooled to below 100℃ at 20~50℃ / s, and then pickled. The pickling is carried out using 55% volume hydrochloric acid at a pickling temperature of 75℃.

[0014] Optionally, in the first cold rolling process, the normalized pickled plate is rolled to the target thickness of 0.365-0.372 mm in 5-6 passes using a single cold rolling method, with a total cold rolling reduction rate of 81.25-84.15%.

[0015] Optionally, in the annealing process, the cold-rolled sheet undergoes continuous annealing at a temperature of 830~900℃ and an annealing time of 240~480s.

[0016] Optionally, in the secondary cold rolling process, the secondary cold rolling reduction rate is required to be controlled at 4%~6%, and the target thickness of the finished product is 0.35mm.

[0017] Optionally, after secondary cold rolling, the insulating coating is applied directly after alkaline washing and then cured at 380~650℃.

[0018] The present invention provides a non-oriented silicon steel for high-speed rotating motors and a method for manufacturing the same, which has the following beneficial effects: This invention employs a design with 1.3~1.6% ultra-low silicon and 0.05~0.10% precisely controlled phosphorus, avoiding high-cost alloying elements and achieving an optimized balance between strength and ductility while ensuring magnetic properties. Traditional techniques rely on high Si / Al solid solution strengthening or Nb / Cu precipitation strengthening to increase strength, but this inevitably leads to a decrease in magnetic induction (e.g., CN107974620B with Nb increased to 0.2%, B...). 5000 Only 1.608T). This invention utilizes hot rolling at low temperatures (650~750℃) combined with normalizing in a two-stage cooling process (first slow cooling at 5~10℃ / s to 600~700℃, then rapid cooling at 20~50℃ / s) to produce silicon steel products for high-speed rotating motors with a thickness of 0.35mm and iron loss P. 1.5 / 50 At 3.1~3.3 W / kg, B 5000 At a strength of 1.72~1.74T, the yield strength is 300~330MPa, the tensile strength is 450~480MPa, and the hardness HV1 is 140~150. A B-grade yield strength of 300MPa is achieved. 5000≥1.72T, which is equivalent to an increase of 5~8% in motor power density, meets the magnetic performance requirements of low iron loss and high magnetic induction for non-oriented silicon steel used in high-speed rotating motors below 10,000r / min, and also meets the high strength requirements of silicon steel materials for high-speed rotating motors. Attached Figure Description

[0019] Figure 1 This is a microstructure diagram of the silicon steel finished product for high-speed rotating motors in Embodiment 1 of the present invention. Detailed Implementation

[0020] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] This embodiment provides a non-oriented silicon steel for high-speed rotating motors, comprising the following components and their weight percentages: C≤0.004%, Si: 1.3~1.6%, Mn: 0.2~0.5%, Als: 0.15~0.30%, P: 0.05~0.10%, S≤0.005%, N≤0.005%, with the remainder being Fe and unavoidable impurities.

[0022] The invention produces a low-cost, high-speed rotating electric motor with excellent magnetic properties and high strength, which meets the magnetic property requirements of non-oriented silicon steel for high-speed rotating electric motors, and also has high mechanical strength, meeting the mechanical strength requirements of silicon steel materials for high-speed rotating electric motors.

[0023] The high-speed rotating motor using non-oriented silicon steel in this embodiment possesses both high strength and high magnetic properties, primarily based on the following principles: C: Although C can improve mechanical properties, it is a harmful element for non-oriented silicon steel, which will deteriorate the magnetic properties of silicon steel. Generally, the C content is required to be no more than 0.005%. Considering the magnetic performance requirements of this invention, it is preferable that the C content be controlled below 0.004%.

[0024] Si: Si can reduce iron loss, and the solid solution strengthening effect of Si can improve mechanical strength. However, as the Si content increases, the magnetic permeability and processing performance will deteriorate, the brittleness of the finished silicon steel will also increase, and the cold rolling processability will deteriorate, which is not conducive to the cold rolling process and the punching of users. Considering that the non-oriented silicon steel for high-speed industrial motors used in this invention belongs to the medium grade series and the requirements for iron loss are not very high, the upper limit of Si content control is 1.6%. At the same time, in order to ensure the mechanical properties of the product, the lower limit of Si content control is 1.3%. Considering the magnetic properties and processing performance of the product, the Si content in this invention is controlled at 1.3%~1.6%.

[0025] Mn: Mn plays a solid solution strengthening role in non-oriented silicon steel, which can improve the product strength and reduce the product iron loss. Mn and S form MnS, which reduces the S dissolved in the slab during heating and can effectively suppress hot brittleness during heating. However, if the Mn content is too high, fine MnS precipitates will be generated during hot rolling, which will prevent grain growth and deteriorate the magnetic properties. Therefore, the Mn content in this invention is controlled at 0.20%~0.50%.

[0026] Phosphorus (P): In silicon steel, phosphorus has a larger atomic radius than Fe and Si, making it an effective solid solution strengthening element. It can improve strength without significantly impairing magnetism. Furthermore, an appropriate amount of phosphorus can optimize texture and increase the proportion of favorable {100} texture components. To ensure product performance, the P content in this invention is controlled to be no less than 0.05%. However, phosphorus has a grain boundary segregation effect, which can easily lead to embrittlement. A P content exceeding 0.10% will significantly worsen processability, which is detrimental to actual production. Therefore, the P content should not be too high; thus, the P content in this invention needs to be controlled between 0.05% and 0.10%.

[0027] Als: Al is similar to Si in that it can improve the magnetic properties and mechanical strength of the product. However, Al has a smaller impact on the brittleness of electrical steel than Si. Considering the magnetic performance requirements of the product, the Al content in this invention should be controlled at 0.15% to 0.3%.

[0028] S, N: S and N are harmful elements. To reduce their impact on the magnetic properties of the product, the content of S is ≤0.005% and the content of N is ≤0.005%.

[0029] This embodiment also provides a method for manufacturing non-oriented silicon steel for high-speed rotating motors, including: Continuous casting of molten steel into slabs; Hot-rolled; Roll up; Pickling; One-time cold rolling; Annealing; and Secondary cold rolling.

[0030] The non-oriented silicon steel products obtained by the above-mentioned process have excellent magnetic properties, meeting the magnetic property requirements of non-oriented silicon steel for high-speed rotating motors, and also have high mechanical strength, meeting the mechanical strength requirements of silicon steel materials for high-speed rotating motors.

[0031] The thickness of the slab continuously cast from molten steel is 200~260mm, and the slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1100~1250℃, and the heating and holding time is not less than 210min.

[0032] During hot rolling, the plate is finished with a thickness of 2.0~2.3mm through 7 passes.

[0033] Furthermore, during hot rolling, the final rolling temperature should be controlled within the range of 650℃ ≤ final rolling temperature ≤ [650℃ + (Si + Al) * 50℃]; that is, the final rolling temperature is preferably controlled between 650 and 745℃. This low-temperature final rolling refines the grains and improves the mechanical strength of the finished product. At the same time, it avoids excessively low final rolling temperatures, which would reduce the {110} texture and enhance both {110} and {111} grains, thus deteriorating the product's magnetic properties.

[0034] Preferably, the winding temperature is controlled at 550~600℃, and the coil is allowed to cool naturally to room temperature after winding. In this way, the winding temperature should not exceed 600℃. A lower winding temperature can improve the mechanical strength of the product and avoid winding temperatures that are too low, especially below 500℃, to prevent the formation of precipitates such as AlN, which can pin grain boundaries during cold rolling annealing and lead to deterioration of the magnetic properties of the finished product.

[0035] Preferably, laminar flow cooling is used before coiling, and a post-cooling method is used to cool the hot-rolled plate.

[0036] During pickling, hot-rolled strip steel passes through a normalizing and pickling line, with the normalizing temperature controlled between 880 and 920°C and the normalizing time between 2 and 4 minutes. This improves the mechanical strength of the finished product and also imparts high magnetic properties.

[0037] Preferably, after normalizing, the strip steel is first cooled to 600-700℃ at 5-10℃ / s, then cooled to below 100℃ at 20-50℃ / s, and then pickled using 55% hydrochloric acid at 75℃. This reduces the internal stress of the strip steel, allowing the grains to fully recover. In addition, this combination of "slow cooling + rapid cooling" can precisely control precipitation behavior: the first stage of slow cooling promotes the uniform distribution of phosphorus and reduces segregation; the second stage of rapid cooling inhibits the precipitation of brittle phases and improves plasticity.

[0038] In the first cold rolling process, the normalized pickled plate is rolled to the target thickness of 0.365-0.372 mm in 5-6 passes using the first cold rolling method, with a total cold rolling reduction rate of 81.25-84.15%.

[0039] During annealing, the cold-rolled sheet undergoes continuous annealing at a temperature of 830~900℃ for 240~480s. This avoids excessively high temperatures that would reduce the product's yield strength and ensure its mechanical properties, while also preventing excessively low temperatures that would hinder recrystallization.

[0040] Preferably, during annealing, a protective atmosphere of H2 and N2 in a volume ratio of 3:7 is used to ensure that the surface is free of defects such as oxidation before secondary cold rolling.

[0041] During the secondary cold rolling process, the reduction rate must be controlled between 4% and 6%, with a target finished product thickness of 0.35 mm. To improve the mechanical strength of the finished product by increasing dislocation density, the strip undergoes a secondary cold rolling process with a reduction rate of no less than 4% after annealing, cold rolling to the target finished product thickness of 0.35 mm. Simultaneously, to reduce the deterioration of finished product performance due to dislocation density, the recrystallization rate after secondary cold rolling must be above 90%, and the secondary reduction rate must not exceed 6%.

[0042] Preferably, the manufacturing method of the non-oriented silicon steel for the high-speed rotating motor further includes: after secondary cold rolling, directly alkali washing, and then applying an insulating coating through a coating roller. Subsequently, the insulating coating is cured at 380~650℃.

[0043] In this embodiment, the silicon steel product has a thickness of 0.35 mm and an iron loss P. 1.5 / 50 Between 3.1 and 3.3 W / kg; B 5000 The strength is between 1.72 and 1.74 T; yield strength is between 300 and 330 MPa; tensile strength is between 450 and 480 MPa; and hardness (HV1) is between 140 and 150. Among these, iron loss P... 1.5 / 50 Core loss at a maximum magnetic flux density of 1.5T under an alternating magnetic field with a frequency of 50Hz; magnetic induction B 5000 The magnetic flux density is given by a magnetic field strength of 5000 A / m; the yield strength and tensile strength are calculated using A... 50 Standard testing.

[0044] The present invention will be described in detail below through embodiments.

[0045] Example 1 A method for manufacturing non-oriented silicon steel for high-speed rotating electric motors specifically includes the following steps: 1) The molten steel refined in the RH furnace is continuously cast into slabs with a thickness of 230mm. The chemical composition of the slabs by weight percentage is C≤0.004%; Si: 1.52%; Als: 0.18%; Mn: 0.25%; P: 0.081%; S≤0.005%; N≤0.005%; with the remainder being Fe and unavoidable impurity elements.

[0046] 2) The temperature of the slab in the heating furnace is 1120℃, and the heating and holding time is 220min; 3) The material is hot-rolled to a thickness of 2.0 mm in 7 passes with a final rolling temperature of 670℃ and a coiling temperature of 570℃. 4) The normalizing temperature is controlled at 910℃ and the normalizing time is 2.5min. After normalizing, it is cooled to 680℃ at 8℃ / s and then cooled to 100℃ at 30℃. Then it is rolled into a cold-rolled sheet of 0.365mm in 6 passes. 5) Annealed at 880℃ for 260 seconds, with a protective atmosphere of H2 and N2 in a 3:7 ratio. 6) After a second cold rolling process with a reduction rate of 4.1%, the material is reduced to the target thickness of 0.35 mm. 7) After alkaline washing, the insulating coating is applied through a coating roller and cured at 380~650℃.

[0047] The non-oriented silicon steel manufactured using the above-mentioned low-temperature final rolling combined with normalizing double cooling process has a finished iron loss P. 1.5 / 50 It is 3.15W / Kg, magnetic induction B 5000 The yield strength is 1.738T, the yield strength is 318MPa, the tensile strength is 462MPa, the hardness HV1 is 145, and the microstructure is as follows. Figure 1 As shown, Figure 1 This is a microstructure diagram of the silicon steel finished product for high-speed rotating motor in Embodiment 1 of the present invention. The structure is ferrite, with some grains not fully grown. The overall recrystallization rate is over 90%. At the same time, due to secondary cold rolling, some grains are elongated and deformed, resulting in a certain degree of plastic deformation.

[0048] Example 2 A method for manufacturing non-oriented silicon steel for high-speed rotating electric motors specifically includes the following steps: 1) The molten steel refined in the RH furnace is continuously cast into slabs with a thickness of 230 mm. The chemical composition of the slabs by weight percentage is C≤0.004%; Si: 1.50%; Als: 0.18%; Mn: 0.25%; P: 0.080%; S≤0.005%; N≤0.005%; with the remainder being Fe and unavoidable impurity elements.

[0049] 2) The temperature of the slab in the heating furnace is 1120℃, and the heating and holding time is 220min; 3) The material is hot-rolled to a thickness of 2.0 mm in 7 passes with a final rolling temperature of 670℃ and a coiling temperature of 570℃. 4) The normalizing temperature is controlled at 890℃ and the normalizing time is 2.5min. After normalizing, it is cooled to 650℃ at 10℃ / s and then cooled to 100℃ at 25℃. Then it is rolled into a cold-rolled sheet of 0.365mm in 6 passes. 5) Annealed at 840℃ for 260 seconds, with a protective atmosphere of H2 and N2 in a 3:7 ratio. 6) After a second cold rolling process with a reduction rate of 4.1%, the material is reduced to the target thickness of 0.35 mm. 7) After alkaline washing, the insulating coating is applied through a coating roller and cured at 380~650℃.

[0050] The non-oriented silicon steel manufactured using the above process has a finished product with a low iron loss P. 1.5 / 50It is 3.29W / Kg, magnetic induction B 5000 It has a strength of 1.735T, a yield strength of 326MPa, a tensile strength of 471MPa, and a hardness HV1 of 144.

[0051] Example 3 A method for manufacturing non-oriented silicon steel for high-speed rotating electric motors specifically includes the following steps: 1) The molten steel refined in the RH furnace is continuously cast into slabs with a thickness of 230 mm. The chemical composition of the slabs by weight percentage is C≤0.004%; Si: 1.39%; Als: 0.20%; Mn: 0.20%; P: 0.06%; S≤0.005%; N≤0.005%; and the remainder is Fe and unavoidable impurity elements.

[0052] 2) The temperature of the slab in the heating furnace is 1130℃, and the heating and holding time is 200min; 3) The material is hot-rolled to a thickness of 2.2 mm in 7 passes with a final rolling temperature of 670℃ and a coiling temperature of 570℃. 4) The normalizing temperature is controlled at 910℃ and the normalizing time is 2.5min. After normalizing, it is cooled to 680℃ at 7℃ / s and then cooled to 100℃ at 30℃. Then it is rolled into a cold-rolled sheet of 0.370mm in 6 passes. 5) Annealed at 880℃ for 260 seconds, with a protective atmosphere of H2 and N2 in a 3:7 ratio. 6) After a second cold rolling process with a reduction rate of 5.4%, the material is reduced to the target thickness of 0.35 mm. 7) After alkaline washing, the insulating coating is applied through a coating roller and cured at 380~650℃.

[0053] The non-oriented silicon steel manufactured using the above process has a finished product with a low iron loss P. 1.5 / 50 It is 3.38W / Kg, magnetic induction B 5000 It has a strength of 1.740T, a yield strength of 320MPa, a tensile strength of 465MPa, and a hardness HV1 of 140.

[0054] Example 4 A method for manufacturing non-oriented silicon steel for high-speed rotating electric motors specifically includes the following steps: 1) The molten steel refined in the RH furnace is continuously cast into slabs with a thickness of 220mm. The chemical composition of the slabs by weight percentage is C≤0.004%; Si:1.55%; Als:0.24%; Mn:0.25%; P:0.08%; S≤0.005%; N≤0.005%; with the remainder being Fe and unavoidable impurity elements.

[0055] 2) The temperature of the slab in the heating furnace is 1240℃, and the heating and holding time is 220min; 3) The material is hot-rolled to a thickness of 2.0 mm in 7 passes with a final rolling temperature of 720℃ and a coiling temperature of 600℃. 4) The normalizing temperature is controlled at 920℃ and the normalizing time is 2.5min. After normalizing, it is cooled to 660℃ at 6℃ / s and then cooled to 100℃ at 27℃. Then it is rolled into a cold-rolled sheet of 0.372mm in 6 passes. 5) Annealed at 900℃ for 260 seconds, with a protective atmosphere of H2 and N2 in a 3:7 ratio. 6) After a second cold rolling process with a reduction rate of 5.9%, the material is reduced to the target thickness of 0.35 mm. 7) After alkaline washing, the insulating coating is applied through a coating roller and cured at 380~650℃.

[0056] The non-oriented silicon steel manufactured using the above process has a finished product with a low iron loss P. 1.5 / 50 It is 3.11 W / Kg, magnetic induction B 5000 It has a strength of 1.732T, a yield strength of 311MPa, a tensile strength of 452MPa, and a hardness HV1 of 146.

[0057] Comparative Example 1 A method for manufacturing non-oriented silicon steel for high-speed rotating electric motors specifically includes the following steps: 1) The molten steel refined in the RH furnace is continuously cast into slabs with a thickness of 220mm. The chemical composition of the slabs by weight percentage is C≤0.004%; Si: 1.20%; Als: 0.30%; Mn: 0.35%; P: 0.04%; S≤0.005%; N≤0.005%; with the remainder being Fe and unavoidable impurity elements.

[0058] 2) The temperature of the slab in the heating furnace is 1120℃, and the heating and holding time is 220min; 3) The material is hot-rolled to a thickness of 2.2 mm in 7 passes with a final rolling temperature of 750℃ and a coiling temperature of 570℃. 4) The normalizing temperature is controlled at 920℃ and the normalizing time is 2.5min. After normalizing, it is naturally cooled to room temperature at 4℃ / s and then rolled to 0.35mm in 6 passes. 5) After annealing at 920℃ for 260s, H2 and N2 are used as a protective atmosphere in a 3:7 ratio. After annealing, the insulating coating is applied by a coating roller and cured at 380~650℃.

[0059] The non-oriented silicon steel manufactured using the above process has a finished product with iron loss P. 1.5 / 50 It is 3.50W / Kg, magnetic induction B 5000 It has a strength of 1.740T, a yield strength of 250MPa, a tensile strength of 340MPa, and a hardness HV1 of 124.

[0060] Comparative Example 2 A method for manufacturing non-oriented silicon steel for high-speed rotating electric motors specifically includes the following steps: 1) The molten steel refined in the RH furnace is continuously cast into slabs with a thickness of 230mm. The chemical composition of the slabs by weight percentage is C≤0.004%; Si:1.55%; Als:0.23%; Mn:0.20%; P:0.08%; S≤0.005%; N≤0.005%; with the remainder being Fe and unavoidable impurity elements.

[0061] 2) The temperature of the slab in the heating furnace is 1260℃, and the heating and holding time is 220min; 3) The material is hot-rolled to a thickness of 2.0 mm in 7 passes with a final rolling temperature of 780℃ and a coiling temperature of 690℃. 4) The normalizing temperature is controlled at 930℃ and the normalizing time is 2.5min. After normalizing, it is naturally cooled to room temperature at 3℃ / s and then rolled to 0.35mm in 6 passes. 5) After annealing at 950℃ for 260s, H2 and N2 are used as a protective atmosphere in a 3:7 ratio. After annealing, the insulating coating is applied by a coating roller and cured at 380~650℃.

[0062] The non-oriented silicon steel manufactured using the above process has a finished product with a low iron loss P. 1.5 / 50 It is 2.90W / Kg, magnetic induction B 5000 It has a strength of 1.72T, a yield strength of 260MPa, a tensile strength of 345MPa, and a hardness HV1 of 146.

[0063] Comparative Example 3 A method for manufacturing non-oriented silicon steel for high-speed rotating electric motors specifically includes the following steps: 1) The molten steel refined in the RH furnace is continuously cast into slabs with a thickness of 230 mm. The chemical composition of the slabs by weight percentage is C≤0.004%; Si: 1.0%; Als: 0.10%; Mn: 0.25%; P: 0.03%; S≤0.005%; N≤0.005%; and the remainder is Fe and unavoidable impurity elements.

[0064] 2) The temperature of the slab in the heating furnace is 1240℃, and the heating and holding time is 220min; 3) The material is hot-rolled to a thickness of 2.0 mm in 7 passes with a final rolling temperature of 760℃ and a coiling temperature of 680℃. 4) The normalizing temperature is controlled at 920℃ and the normalizing time is 2.5min. After normalizing, it is naturally cooled to room temperature at 4℃ / s and then rolled to 0.365mm in 6 passes. 5) Annealed at 950℃ for 260s, with H2 and N2 in a 3:7 ratio as the protective atmosphere; 6) After a second cold rolling process with a reduction rate of 5.9%, the material is reduced to the target thickness of 0.35 mm. 7) After alkaline washing, the insulating coating is applied through a coating roller and cured at 380~650℃.

[0065] The non-oriented silicon steel manufactured using the above process has a finished product with a low iron loss P. 1.5 / 50 It is 3.40W / Kg, magnetic induction B 5000 It has a strength of 1.745T, a yield strength of 245MPa, a tensile strength of 335MPa, and a hardness HV1 of 120.

[0066] Comparative Example 4 A method for manufacturing non-oriented silicon steel for high-speed rotating electric motors specifically includes the following steps: 1) The molten steel refined in the RH furnace is continuously cast into slabs with a thickness of 230mm. The chemical composition of the slabs by weight percentage is C≤0.004%; Si:1.5%; Als:0.18%; Mn:0.25%; P:0.08%; S≤0.005%; N≤0.005%; and the remainder is Fe and unavoidable impurity elements.

[0067] 2) The temperature of the slab in the heating furnace is 1120℃, and the heating and holding time is 220min; 3) The material is hot-rolled to a thickness of 2.0 mm in 7 passes with a final rolling temperature of 670℃ and a coiling temperature of 570℃. 4) The normalizing temperature is controlled at 890℃ and the normalizing time is 2.5min. After normalizing, it is naturally cooled to room temperature at 4℃ / s and then rolled to 0.30mm in 6 passes. 5) Anneal at 840℃ for 260s, with H2 and N2 in a 3:7 protective atmosphere. Apply insulating coating using a coating roller and cure at 380~650℃.

[0068] The non-oriented silicon steel manufactured using the above process has a finished product with a low iron loss P. 1.5 / 50 It is 3.28W / Kg, magnetic induction B 5000 It has a strength of 1.731T, a yield strength of 298MPa, a tensile strength of 455MPa, and a hardness HV1 of 143.

[0069] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A non-oriented silicon steel for high-speed rotating electric motors, characterized in that, The components and their weight percentages are as follows: C≤0.004%, Si: 1.3~1.6%, Mn: 0.2~0.5%, Als: 0.15~0.30%, P: 0.05~0.10%, S≤0.005%, N≤0.005%, with the remainder being Fe and unavoidable impurities.

2. A method for manufacturing non-oriented silicon steel for high-speed rotating motors as described in claim 1, characterized in that, The manufacturing method includes: Continuous casting of molten steel into slabs; Hot-rolled; Roll up; Pickling; One-time cold rolling; Annealing; and Secondary cold rolling; The silicon steel product has a thickness of 0.35mm and an iron loss P. 1.5 / 50 At 3.1~3.3 W / kg, B 5000 The yield strength is between 1.72 and 1.74 T, the yield strength is between 300 and 330 MPa, the tensile strength is between 450 and 480 MPa, and the hardness HV1 is between 140 and 150.

3. The method for manufacturing non-oriented silicon steel for high-speed rotating motors as described in claim 2, characterized in that, In the continuous steel casting process, the thickness of the cast slab is 200~260mm, and the slab is directly loaded into the heating furnace for heating. The temperature of the heating furnace is controlled at 1100~1250℃, and the heating and holding time is not less than 210min.

4. The method for manufacturing non-oriented silicon steel for high-speed rotating motors as described in claim 2, characterized in that, In the hot rolling process, the hot-rolled plate is rolled into a thickness of 2.0~2.3mm through 7 passes, and the final rolling temperature is required to be controlled at 650~745℃.

5. The method for manufacturing non-oriented silicon steel for high-speed rotating motors as described in claim 2, characterized in that, In the winding process, the winding temperature is controlled at 550~600℃, and the winding is allowed to cool naturally to room temperature after winding.

6. The method for manufacturing non-oriented silicon steel for high-speed rotating motors as described in claim 2, characterized in that, In the pickling process, the hot-rolled strip steel passes through a normalizing and pickling line. The normalizing temperature is controlled at 880~920℃ and the normalizing time is 2~4 minutes. After normalizing, the hot-rolled strip steel is first cooled to 600~700℃ at 5~10℃ / s, and then cooled to below 100℃ at 20~50℃ / s. Then it is pickled. The pickling is carried out with 55% volume hydrochloric acid at a pickling temperature of 75℃.

7. The method for manufacturing non-oriented silicon steel for high-speed rotating motors as described in claim 2, characterized in that, In the aforementioned cold rolling process, the normalized pickled plate is rolled to a target thickness of 0.365-0.372 mm in 5-6 passes using a single cold rolling method, with a total cold rolling reduction rate of 81.25-84.15%.

8. The method for manufacturing non-oriented silicon steel for high-speed rotating motors as described in claim 2, characterized in that, In the annealing process, the cold-rolled sheet undergoes continuous annealing at a temperature of 830~900℃ for a time of 240~480s.

9. The method for manufacturing non-oriented silicon steel for high-speed rotating motors as described in claim 2, characterized in that, In the secondary cold rolling process, the secondary cold rolling reduction rate is required to be controlled at 4%~6%, and the target thickness of the finished product is 0.35mm.

10. The method for manufacturing non-oriented silicon steel for high-speed rotating motors as described in claim 2, characterized in that, This also includes applying insulating coating after direct alkaline washing following secondary cold rolling, followed by curing the insulating coating at 380~650℃.

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