Non-oriented electrical steel

Abstract

The application discloses a kind of non-oriented electrical steel, by the secondary annealing of substrate preparation is obtained, the secondary annealing includes: stage one heating: heating to 800~820 ℃ at a rate of 8~12 ℃ / min, 1~3h is kept; Stage two cooling: cooling to 590~610 ℃ at a rate of 2~4 ℃ / min;Stage three cooling: to 25~30 ℃ by 4~6 ℃ / min rate is reduced.The application is optimized by accurate component design and segmented secondary annealing process, realizes the iron loss reduction and magnetic property promotion of non-oriented electrical steel, adapts high-end compressor core demand, process is stable and easy to industrialization promotion.

Description

Technical Field

[0001] This invention relates to the field of non-oriented electrical steel manufacturing technology, and specifically to a non-oriented electrical steel. Background Technology

[0002] Non-oriented electrical steel is a core magnetic material used in the manufacture of compressor and transformer cores. Its magnetic flux density and iron loss level directly determine the energy efficiency and operational stability of the end equipment. 50W800 is the mainstream grade for compressor cores and has the largest market application. However, during the forming process such as lamination, stacking, and riveting, the edge grain structure is prone to deformation, leading to residual stress accumulation, increased hysteresis loss, and decreased magnetic permeability, ultimately resulting in deterioration of magnetic properties. Therefore, the core after lamination needs to undergo secondary annealing to eliminate adverse effects.

[0003] Currently, most research on secondary annealing processes focuses on residual stress relief, but there are few reports on the synergistic control of secondary annealing temperature on the grain size, precipitate distribution, and magnetic flux density of non-oriented electrical steel. The magnetic flux density (J) of 50W800 after secondary annealing is currently unknown. 50 The iron loss is mostly between 1.68 and 1.71 tons, and it is difficult to reduce the iron loss to below 3.7 W / kg, which cannot meet the dual requirements of high magnetic induction and low iron loss of high-end compressors. Summary of the Invention

[0004] To address the aforementioned technical deficiencies, this invention provides a non-oriented electrical steel. By precisely designing the chemical composition range and employing a segmented secondary annealing process, residual stress is eliminated, grain size is optimized, harmful precipitates are controlled, and beneficial texture is strengthened. This reduces iron loss to 3.7 W / kg or below while increasing magnetic flux density to 1.72 T or higher, meeting the requirements of high-end compressors.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A non-oriented electrical steel is prepared by subjecting a substrate to secondary annealing, wherein the secondary annealing includes: Stage 1 heating: Increase the temperature to 800-820℃ at a rate of 8-12℃ / min, and hold for 1-3 hours; Phase Two Cooling: Cool down to 590-610℃ at a rate of 2-4℃ / min; Phase 3 cooling: Reduce the temperature to 25-30℃ at a rate of 4-6℃ / min.

[0006] In a preferred embodiment of the present invention, by increasing the temperature in stage one, the grains in the substrate can be promoted to grow uniformly to 53-59 μm, while some 0.1-0.2 μm MnS-Cu grains can be grown. x S is a harmless precipitate with a fine precipitate size of 0.2~0.5μm, which reduces magnetic domain wall pinning points.

[0007] In a preferred embodiment of the present invention, the crystal orientation of the substrate can be stabilized by cooling in stages two and three.

[0008] As a further aspect of the present invention, the Si content in the substrate is 0.80~0.90wt%, preferably 0.85~0.90wt%.

[0009] As a further aspect of the present invention, the C element content in the substrate is 0~0.0022wt%, preferably 0.0020~0.0022wt%.

[0010] As a further aspect of the present invention, the Mn content in the substrate is 0.19~0.21wt%.

[0011] As a further aspect of the present invention, the P element content in the substrate is 0~0.02wt%, preferably 0.018~0.02wt%.

[0012] As a further aspect of the present invention, the sulfur content in the substrate is 0~0.0024wt%, preferably 0.0022~0.0024wt%.

[0013] As a further aspect of the present invention, the Al content in the substrate is 0.21~0.25wt%, preferably 0.225~0.235wt%.

[0014] As a further aspect of the present invention, the nitrogen content in the substrate is 0~0.0018wt%, preferably 0.0016~0.0018wt%.

[0015] As a further aspect of the present invention, the chemical composition of the substrate includes: 0~0.0022wt% C, 0.80~0.90wt% Si, 0.19~0.21wt% Mn, 0~0.02wt% P, 0~0.0024wt% S, 0.21~0.25wt% Al, 0~0.0018wt% N, with the balance being Fe and unavoidable impurities.

[0016] As a further aspect of the present invention, the average grain size of the substrate is 33.47~34.69 μm.

[0017] As a further aspect of the present invention, the total proportion of (100) and (110) crystal textures in the substrate is ≥48%, preferably 48%~51%.

[0018] As a further aspect of the present invention, the secondary annealing is performed under a protective atmosphere.

[0019] As a further aspect of the present invention, the secondary annealing is performed under at least one protective atmosphere, namely argon or nitrogen.

[0020] As a further aspect of the present invention, the secondary annealing is performed under a nitrogen protective atmosphere.

[0021] As a further aspect of the present invention, the purity of the nitrogen gas is ≥99.9%.

[0022] As a further aspect of the present invention, the pressure of the secondary annealing is 0.09~0.10MPa.

[0023] As a further aspect of the present invention, the secondary annealing is performed in a vacuum furnace.

[0024] As a further aspect of the present invention, the vacuum annealing furnace has a vacuum degree ≥0.09MPa and an internal dew point ≤-40℃ to avoid sample oxidation affecting magnetic properties.

[0025] As a further aspect of the present invention, the fluctuation range of the temperature change rate during the first stage of heating is ≤ ±0.3℃ / min.

[0026] As a further aspect of the present invention, the fluctuation range of the temperature change rate during the second cooling stage is ≤ ±0.3℃ / min.

[0027] As a further aspect of the present invention, the fluctuation range of the temperature change rate in the third stage of cooling is ≤ ±0.3℃ / min.

[0028] In a preferred embodiment of the present invention, by controlling the fluctuation range of the temperature change rate during the first heating stage, the temperature change rate during the second cooling stage, and the temperature change rate during the third cooling stage within ±0.3℃ / min, uniform grain growth and texture stability can be ensured.

[0029] As a further aspect of the present invention, the grain structure of the non-oriented electrical steel is a uniform equiaxed grain.

[0030] As a further aspect of the present invention, the average grain size of the non-oriented electrical steel is 53~59μm.

[0031] As a further aspect of the present invention, the precipitated phase of the non-oriented electrical steel includes MnS-Cu. x S, where x = 1~2.

[0032] As a further aspect of the present invention, the proportion of 0.1~0.2μm precipitates in the non-oriented electrical steel is 60%~63%, preferably 61%~62.13%.

[0033] As a further aspect of the present invention, the combined proportion of (100) and (110) crystal textures in the non-oriented electrical steel is 65% to 70%, and more preferably 65% ​​to 68%.

[0034] As a further aspect of the present invention, the (111) crystal texture of the non-oriented electrical steel accounts for ≤28%.

[0035] As a further aspect of the present invention, the iron loss P of the non-oriented electrical steel 1.5 / 50 The concentration is 3.60~3.75 W / kg, preferably 3.60~3.70 W / kg.

[0036] As a further aspect of the present invention, the magnetic polarization intensity J of the non-oriented electrical steel 50 The value is 1.70~1.75T, preferably 1.72~1.73T.

[0037] As a further aspect of the present invention, the non-oriented electrical steel contains 0.0020~0.0022wt% C, 0.85~0.90wt% Si, 0.20wt% Mn, and 0.23wt% Al.

[0038] As a further aspect of the present invention, the substrate is pretreated.

[0039] As a further aspect of the present invention, the pretreatment includes at least one of stamping, stacking, riveting, and shearing.

[0040] As a further aspect of the present invention, the shearing accuracy error during the pretreatment process is ≤ ±0.1mm, to avoid excessive residual stress caused by processing deformation.

[0041] As a further aspect of the present invention, the substrate includes an annealed plate, preferably a 50W800 annealed plate.

[0042] As a further aspect of the present invention, the non-oriented electrical steel is prepared by the following method: S1. A substrate with a chemical composition including 0~0.0022wt% C, 0.80~0.90wt% Si, 0.19~0.21wt% Mn, 0~0.02wt% P, 0~0.0024wt% S, 0.21~0.25wt% Al, 0~0.0018wt% N, and the balance being Fe and unavoidable impurities, is cut and shaped. S2. Secondary annealing is performed under nitrogen as a protective atmosphere to obtain the non-oriented electrical steel. The secondary annealing includes: Stage 1 heating: Increase the temperature to 800-820℃ at a rate of 8-12℃ / min, and hold for 1-3 hours; Phase Two Cooling: Cool down to 590-610℃ at a rate of 2-4℃ / min; Phase 3 cooling: Reduce the temperature to 25-30℃ at a rate of 4-6℃ / min.

[0043] As a further aspect of the present invention, the thickness of the non-oriented electrical steel is 0.5 mm.

[0044] As a further aspect of the present invention, the non-oriented electrical steel includes 50W800 grade steel.

[0045] As a further aspect of the present invention, the total unavoidable impurity content in the non-oriented electrical steel is ≤0.008%, and it does not contain coarse oxide or nitride precipitates with a size >1.0μm.

[0046] As a further aspect of the present invention, the chemical composition of the non-oriented electrical steel, by mass percentage, is: C≤0.0022%, Si 0.80~0.90%, Mn 0.19~0.21%, P≤0.02%, S≤0.0024%, Al 0.23%, N≤0.0018%, with the balance being Fe and unavoidable impurities.

[0047] As a further aspect of the present invention, the grain structure of the non-oriented electrical steel is uniform equiaxed crystal with an average grain size of 53~59μm, and the precipitated phases are mainly MnS-Cu. x S, wherein the proportion of fine precipitates of 0.1~0.2μm is ≤62.13%; the crystal texture satisfies the following: (100)+(110) favorable texture proportion ≥65%, (111) unfavorable texture proportion ≤28%; the electromagnetic performance index is: iron loss P 1.5 / 50 ≤3.7W / kg, magnetic polarization J 50 ≥1.72T.

[0048] As a further aspect of the present invention, the non-oriented electrical steel is prepared by performing a secondary annealing on a substrate, wherein the secondary annealing includes: Stage 1 heating: Increase the temperature to 800-820℃ at a rate of 8-12℃ / min, and hold for 1-3 hours; Phase Two Cooling: Cool down to 590-610℃ at a rate of 2-4℃ / min; Phase 3 cooling: Cooling to 25-30℃ at a rate of 4-6℃ / min; The chemical composition of the substrate includes 0~0.0022wt% C, 0.80~0.90wt% Si, 0.19~0.21wt% Mn, 0~0.02wt% P, 0~0.0024wt% S, 0.21~0.25wt% Al, and 0~0.0018wt% N, with the balance being Fe and unavoidable impurities. The substrate is pretreated, and the pretreatment includes one of shearing, stacking, and riveting.

[0049] The present invention has at least the following technical effects: By optimizing the chemical composition of the substrate, especially by controlling the Si content within the range of 0.80~0.90wt%, the substrate can achieve both iron loss improvement potential and magnetic stability. Simultaneously, by combining precise temperature control, heat preservation, and cooling processes, the non-oriented electrical steel can achieve a grain size of 55~59μm while reducing the proportion of harmful precipitates of 0.1~0.2μm to below 62.13%, strengthening the (100)+(110) favorable texture, and achieving J... 50 ≥1.72T and P 1.5 / 50 The performance breakthrough of ≤3.7W / kg solves the problem that it is difficult to achieve high magnetic induction and low iron loss at the same time in existing technologies.

[0050] In a preferred embodiment of the present invention, by further precisely controlling the C content of the substrate to ≤0.0022wt% and the N content to ≤0.0018wt%, harmful precipitates such as carbides and nitrides are reduced. Combined with a fixed deoxidation ratio of Al content of about 0.23%, the grains are ensured to grow uniformly to 55~59μm, avoiding microstructure inhomogeneity caused by abnormal growth and enhancing the microstructure stability of non-oriented electrical steel.

[0051] In a preferred embodiment of the present invention, by controlling the heat preservation temperature at around 810°C and coordinating it with the chemical composition of the substrate, the harmful precipitates are efficiently regulated, so that the proportion of fine precipitates of 0.1~0.2μm in the non-oriented electrical steel is ≤62.13%, which significantly reduces the magnetic domain wall pinning effect, ensuring both the improvement of magnetic induction and further reducing hysteresis loss.

[0052] The high magnetic induction, low iron loss, non-oriented electrical steel provided by this invention is prepared by secondary annealing of the substrate. The chemical composition range is adapted to the composition fluctuations in industrial production. The secondary annealing process does not require special equipment and can be directly connected to existing production lines. It has strong industrial adaptability, high production efficiency, controllable cost, and is easy to promote on a large scale. Attached Figure Description

[0053] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0054] Figure 1 This is a metallographic microstructure of the annealed plate in Embodiment 4 of the present invention; Figure 2 The image shows the metallographic microstructure of the non-oriented electrical steel produced in Example 4 of this invention. Figure 3 The image shows the metallographic microstructure of the non-oriented electrical steel produced in Example 5 of this invention. Figure 4 The image shows the metallographic microstructure of the non-oriented electrical steel produced in Example 6 of this invention. Figure 5 The image shows the metallographic microstructure of the non-oriented electrical steel produced in Example 7 of this invention. Figure 6 The image shows the metallographic microstructure of the non-oriented electrical steel produced in Example 8 of this invention. Figure 7 This is a metallographic microstructure of the annealed plate in Embodiment 9 of the present invention; Figure 8 The image shows the metallographic microstructure of the non-oriented electrical steel produced in Example 9 of this invention. Figure 9 The image shows the metallographic microstructure of the non-oriented electrical steel produced in Example 10 of this invention. Figure 10 The image shows the metallographic microstructure of the non-oriented electrical steel produced in Example 11 of this invention. Figure 11 The image shows the metallographic microstructure of the non-oriented electrical steel produced in Example 12 of this invention. Figure 12 This is a metallographic microstructure of the non-oriented electrical steel produced in Example 13 of the present invention.

[0055] Figure caption: Scale bar is 50 μm. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments.

[0057] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0058] To make the technical solution of the present invention clearer and easier to understand, the present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0059] Example 1 A non-oriented electrical steel, the production method of which includes the following steps: (1) Raw material preparation: The chemical composition (mass percentage) selected is: C=0.0020%, Si=0.85%, Mn=0.20%, P=0.018%, S=0.0023%, Al=0.23%, N=0.0017%, with the balance being Fe and unavoidable impurities. The annealed plate has an original grain size of 33.47μm and a (100)+(110) texture ratio of 48%. (2) Stamping: Shearing into 30mm×320mm block samples, stacking and forming, with a shearing accuracy error of ±0.08mm; (3) Secondary annealing: Nitrogen gas with a purity of ≥99.9% is introduced into the vacuum annealing furnace, and the protective atmosphere pressure is 0.09MPa. First, the temperature is raised to 810℃ at 10℃ / min and held for 2 hours; then the temperature is lowered to 600℃ at 3℃ / min, and finally slowly cooled to room temperature (25~30℃) at 5℃ / min to obtain non-oriented electrical steel.

[0060] Testing revealed that the non-oriented electrical steel has a uniform equiaxed grain structure with an average grain size of 53 μm and a 0.1~0.2 μm MnS-Cu content. x S precipitates account for 62.13%, (100)+(110) texture accounts for 65%; electromagnetic properties are: iron loss P 1.5 / 50 =3.68W / kg, magnetic polarization J 50 =1.72T.

[0061] Example 2 A non-oriented electrical steel, the production method of which includes the following steps: (1) Raw material preparation: The chemical composition (mass percentage) selected is: C=0.0022%, Si=0.90%, Mn=0.20%, P=0.02%, S=0.0024%, Al=0.23%, N=0.0018%, with the balance being Fe and unavoidable impurities. The annealed plate has an original grain size of 34.12μm and a (100)+(110) texture accounting for 50%. (2) Stamping: cut into 30mm×320mm block samples, and complete the riveting forming. The cutting accuracy error is ±0.09mm. (3) Secondary annealing: Nitrogen gas with a purity of ≥99.9% is introduced into the vacuum annealing furnace, the protective atmosphere pressure is 0.10MPa, the temperature is first raised to 810℃ at 10℃ / min, held for 2 hours, then cooled to 600℃ at 3℃ / min, and finally slowly cooled to room temperature (25~30℃) at 5℃ / min to obtain non-oriented electrical steel.

[0062] Testing revealed that the non-oriented electrical steel has a uniform equiaxed grain structure with an average grain size of 59 μm and a 0.1~0.2 μm MnS-Cu content. x S precipitates account for 61.85%, (100)+(110) texture accounts for 68%; electromagnetic properties are: iron loss P 1.5 / 50 =3.65W / kg, magnetic polarization J 50 =1.73T.

[0063] Example 3 A non-oriented electrical steel, the production method of which includes the following steps: (1) Raw material preparation: The chemical composition (mass percentage) selected is: C=0.0021%, Si=0.80%, Mn=0.19%, P=0.019%, S=0.0022%, Al=0.23%, N=0.0016%, with the balance being Fe and unavoidable impurities. The annealed plate has an original grain size of 34.69μm and a (100)+(110) texture accounting for 49%. (2) Stamping: Shearing into 30mm×320mm block samples, stacking and forming, with a shearing accuracy error of ±0.1mm; (3) Secondary annealing: Nitrogen gas with a purity of ≥99.9% is introduced into the vacuum annealing furnace, the protective atmosphere pressure is 0.095MPa, the temperature is first raised to 810℃ at 10℃ / min, held for 2 hours, then cooled to 600℃ at 3℃ / min, and finally slowly cooled to room temperature (25~30℃) at 5℃ / min to obtain non-oriented electrical steel.

[0064] Testing revealed that the non-oriented electrical steel has a uniform equiaxed grain structure with an average grain size of 55 μm and a 0.1~0.2 μm MnS-Cu content. x S precipitates account for 62.01%, (100)+(110) texture accounts for 66%; electromagnetic properties are: iron loss P 1.5 / 50 =3.70W / kg, magnetic polarization J 50 =1.72T.

[0065] Comparative Example 1 A non-oriented electrical steel, the production method of which includes the following steps: Annealed plates with the following chemical composition (mass percentage): C=0.0022%, Si=0.91%, Mn=0.20%, Al=0.23%, with the balance being Fe and unavoidable impurities were selected. After lamination, the plates were annealed at a single temperature of 780℃, held at that temperature for 2 hours, and then cooled to room temperature (25~30℃) at a rate of 3℃ / min to obtain non-oriented electrical steel.

[0066] Testing revealed that the average grain size of this non-oriented electrical steel was 58 μm, with 0.1~0.2 μm MnS-Cu content. x S precipitation phase accounted for 68.2%, (100)+(110) texture accounted for 42%, and (111) texture accounted for 35%; iron loss P 1.5 / 50 =3.74W / kg, magnetic polarization J 50 =1.68T.

[0067] Comparative Example 2 The difference from Example 1 is that the chemical composition (mass percentage) of the annealed plate is: C=0.0025%, Si=0.75%, Mn=0.18%, Al=0.22%, with the balance being Fe and unavoidable impurities.

[0068] Testing revealed that the average grain size of this non-oriented electrical steel was 52 μm, with 0.1~0.2 μm MnS-Cu content. x S precipitation phase accounted for 67.59%, (100)+(110) texture accounted for 58%; iron loss P 1.5 / 50 =3.82W / kg, magnetic polarization J 50 =1.70T.

[0069] Comparing the non-oriented electrical steel obtained in Examples 1-3 with that in Comparative Example 1, it can be seen that during secondary annealing, holding the temperature at around 810℃ first can increase the grain size to 53-59μm, which reduces the number of magnetic domain walls, lowers hysteresis loss, and avoids the increase in eddy current loss caused by excessively large grains. Then, by using a segmented cooling process to stabilize the favorable texture, the proportion of (100)+(110) is increased to ≥65%, while the proportion of harmful precipitates of 0.1~0.2μm is reduced to below 62.13%, which is P 1.5 / 50 ≤3.7W / kg, J 50 ≥1.72T provides dual protection.

[0070] Comparing the non-oriented electrical steel obtained in Examples 1-3 with that in Comparative Example 2, it can be seen that the reduction in iron loss is more significant when Si ≥ 0.8%. In this invention, by controlling the silicon content in the electrical steel within the range of 0.80% to 0.90%, the improvement effect of high silicon content on the iron loss of non-oriented electrical steel can be achieved, while avoiding the deterioration of magnetic induction caused by excessively high silicon content (e.g., > 0.9%).

[0071] Example 4 The difference from Example 1 is that the chemical composition (mass percentage) of the annealed plate is: C=0.0022%, Si=0.80%, Mn=0.20%, P=0.018%, S=0.0023%, Al=0.22%, N=0.0016%, with the balance being Fe and unavoidable impurities.

[0072] Metallographic microstructure of the annealed plate as shown in the figure. Figure 1 As shown.

[0073] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 2 As shown.

[0074] Example 5 The difference from Example 4 is that the temperature is raised to 720°C during the second annealing.

[0075] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 3 As shown.

[0076] Example 6 The difference from Example 4 is that the temperature is raised to 750°C during the second annealing.

[0077] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 4 As shown.

[0078] Example 7 The difference from Example 4 is that the temperature is raised to 780°C during the second annealing.

[0079] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 5 As shown.

[0080] Example 8 The difference from Example 4 is that the temperature is raised to 840°C during the second annealing.

[0081] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 6 As shown.

[0082] Example 9 The difference from Example 1 is that the chemical composition (mass percentage) of the annealed plate is: C=0.0020%, Si=0.90%, Mn=0.19%, P=0.02%, S=0.0022%, Al=0.24%, N=0.0017%, with the balance being Fe and unavoidable impurities.

[0083] Metallographic microstructure of the annealed plate as shown in the figure. Figure 7 As shown.

[0084] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 8 As shown.

[0085] Example 10 The difference from Example 9 is that the temperature is raised to 720°C during the second annealing.

[0086] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 9 As shown.

[0087] Example 11 The difference from Example 9 is that the temperature is raised to 750°C during the second annealing.

[0088] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 10 As shown.

[0089] Example 12 The difference from Example 9 is that the temperature is raised to 780°C during the second annealing.

[0090] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 11 As shown.

[0091] Example 13 The difference from Example 9 is that the temperature is raised to 840°C during the second annealing.

[0092] Metallographic microstructure of the produced non-oriented electrical steel is shown in the figure. Figure 12 As shown.

[0093] All process parameters in the embodiments of the present invention are based on the design of existing industrial production lines. Performance stability can be achieved by fine-tuning the annealing temperature and cooling rate, and the results are fully repeatable.

[0094] In summary, this invention addresses the shortcomings of existing non-oriented electrical steels, such as the deterioration of magnetic properties after stamping and the difficulty of achieving both high magnetic induction and low iron loss in traditional secondary annealing processes. It provides a high-magnetic-induction, low-iron-loss non-oriented electrical steel. This high-magnetic-induction, low-iron-loss non-oriented electrical steel achieves a breakthrough in magnetic properties through precise composition design and synergistic optimization of a segmented secondary annealing process. Its chemical composition, by mass percentage, is: C≤0.0022%, Si 0.80~0.90%, Mn 0.19~0.21%, P≤0.02%, S≤0.0024%, Al 0.22~0.23%, N≤0.0018%, with the balance being Fe and unavoidable impurities. This non-oriented electrical steel exhibits uniform equiaxed crystals with an average grain size of 53~59 μm, and the precipitated phases are mainly MnS-Cu. x S, with a fine precipitate ratio of 0.1~0.2μm ≤62.13%, and electromagnetic properties meeting the iron loss P requirement. 1.5 / 50 ≤3.7W / kg, magnetic polarization J 50 ≥1.72T.

[0095] The core production method of this non-oriented electrical steel is a two-stage annealing process of precise heating-holding-segmented cooling: heating to 805-815℃ at a rate of 9-11℃ / min, holding for 1.5-2.5 hours, cooling to 550-650℃ at a rate of 2.5-3.5℃ / min, and then slow cooling at a rate of 4.5-5.5℃ / min.

[0096] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A non-oriented electrical steel, characterized in that, The substrate is prepared by a secondary annealing process, wherein the secondary annealing includes: Stage 1 heating: Increase the temperature to 800-820℃ at a rate of 8-12℃ / min, and hold for 1-3 hours; Phase Two Cooling: Cool down to 590-610℃ at a rate of 2-4℃ / min; Phase 3 cooling: Reduce the temperature to 25-30℃ at a rate of 4-6℃ / min.

2. The non-oriented electrical steel according to claim 1, characterized in that, The Si content in the substrate is 0.80~0.90wt%.

3. The non-oriented electrical steel according to claim 1, characterized in that, In the substrate: The carbon content is 0~0.0022 wt%; And / or, the Mn element content is 0.19~0.21 wt%; And / or, the content of phosphorus is 0~0.02 wt%; And / or, the sulfur content is 0~0.0024 wt%; And / or, the Al element content is 0.21~0.25 wt%; And / or, the nitrogen content is 0~0.0018wt%.

4. The non-oriented electrical steel according to claim 1, characterized in that, The average grain size of the substrate is 33.47~34.69 μm; And / or, the combined proportion of (100) and (110) crystal textures in the substrate is 48% to 51%.

5. The non-oriented electrical steel according to claim 1, characterized in that, The secondary annealing is performed under a protective atmosphere; And / or, the secondary annealing is performed under at least one protective atmosphere of argon or nitrogen; And / or, the secondary annealing is performed under a nitrogen protective atmosphere; And / or, the pressure of the secondary annealing is 0.09~0.10MPa.

6. The non-oriented electrical steel according to claim 1, characterized in that, The fluctuation range of the temperature change rate during the first stage of heating is ≤ ±0.3℃ / min; And / or, the fluctuation range of the temperature change rate during the second cooling stage is ≤ ±0.3℃ / min; And / or, the fluctuation range of the temperature change rate during the third cooling stage is ≤ ±0.3℃ / min.

7. The non-oriented electrical steel according to claim 1, characterized in that, The average grain size of the non-oriented electrical steel is 53~59μm; And / or, the proportion of 0.1~0.2μm precipitates in the non-oriented electrical steel is 60%~63%; And / or, the combined proportion of (100) and (110) crystal textures in the non-oriented electrical steel is 65%~70%; And / or, the iron loss P of the non-oriented electrical steel 1.5 / 50 It is 3.60~3.75 W / kg; And / or, the magnetic polarization J of the non-oriented electrical steel 50 It is 1.70~1.75T.

8. The non-oriented electrical steel according to claim 1, characterized in that, The substrate is pretreated.

9. The non-oriented electrical steel according to claim 8, characterized in that, The pretreatment includes at least one of stamping, stacking, riveting, and shearing.

10. The non-oriented electrical steel according to claim 1, characterized in that, The non-oriented electrical steel includes 50W800 grade steel.

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