Non-oriented electrical steel plate with excellent electromagnetic performance and manufacturing method thereof

Abstract

The invention discloses a non-oriented electrical steel plate with excellent electromagnetic performance, which contains Fe and inevitable impurities, and further contains the following chemical elements in percentage by mass: 0 < C < = 0.003%, 1.2-2.4% of Si, 0.05-0.5% of Mn, 0.03-0.12% of P, 0 < Al < = 0.4%, 0.0002-0.004% of Mg, 0.01-0.20% of Cr and the balance of Fe. Wherein the mass percentage content of P and Cr is 0.05-0.28%. The invention also discloses a manufacturing method of the non-oriented electrical steel plate. The manufacturing method comprises the following steps: smelting and casting; heating is performed; hot rolling; performing cold rolling after pickling; and continuously annealing.

Description

Technical Field

[0001] This invention relates to a steel plate and a method for manufacturing the same, and more particularly to a non-oriented electrical steel plate and a method for manufacturing the same. Background Technology

[0002] In industrial production, there are high requirements for low iron loss and high magnetic induction of non-oriented electrical steel sheets.

[0003] To this end, a large amount of Si, Mn, and Al alloying elements can be added to the steel to increase the resistivity of the material, thereby effectively reducing the iron loss of the material; an appropriate amount of Sn and Sb alloying elements can also be added to the steel to increase the proportion of favorable crystal texture of the material, and to increase the hot rolling final rolling temperature, coiling temperature and normalizing intermediate annealing temperature to obtain a coarse and well-developed hot rolling recrystallization microstructure.

[0004] However, the manufacturing cost of non-oriented electrical steel sheets obtained by the above technology is very high and the cost-effectiveness is low. Furthermore, as the intermediate annealing temperature increases, the cold rolling rollability deteriorates sharply, leading to a decrease in production stability.

[0005] Therefore, there is a need for a non-oriented electrical steel sheet that has excellent electromagnetic properties, can effectively reduce the manufacturing cost of steel, and ensures stable cold rolling. Summary of the Invention

[0006] One of the objectives of this invention is to provide a non-oriented electrical steel sheet with excellent electromagnetic properties. By rationally designing its chemical composition, this steel sheet achieves excellent electromagnetic properties while also having good cold-rolling processing performance and a higher cost-effectiveness.

[0007] To achieve the above objectives, the present invention provides a non-oriented electrical steel sheet with excellent electromagnetic properties, which contains Fe and unavoidable impurities, and also contains the following chemical elements in the following mass percentages:

[0008] The composition is as follows: 0 < C ≤ 0.003%, Si: 1.2–2.4%, Mn: 0.05–0.5%, P: 0.03–0.12%, 0 < Al ≤ 0.4%, Mg: 0.0002–0.004%, Cr: 0.01–0.20%; wherein the mass percentage of P+Cr is 0.05–0.28%.

[0009] Furthermore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage content of each chemical element is as follows:

[0010] 0 < C ≤ 0.003%, Si: 1.2–2.4%, Mn: 0.05–0.5%, P: 0.03–0.12%, 0 < Al ≤ 0.4%, Mg: 0.0002–0.004%, Cr: 0.01–0.20%; balance is Fe and unavoidable impurities.

[0011] The mass percentage of P+Cr is 0.05%–0.28%.

[0012] The design principles of each chemical element in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention are as follows:

[0013] C: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the content of element C is higher than 0.003%, magnetic aging will occur, deteriorating the electromagnetic properties of the steel. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage content of element C is controlled between 0 < C ≤ 0.003%.

[0014] Si: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the Si content is below 1.2%, the iron loss of the steel cannot be effectively reduced; when the Si content is above 2.4%, the cold rolling stability will be significantly reduced. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of Si is controlled between 1.2% and 2.4%.

[0015] Mn: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the Mn content is below 0.05%, the austenite phase region cannot be effectively expanded; when the Mn content is above 0.5%, it leads to a significant increase in cost. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of Mn is controlled between 0.05% and 0.5%.

[0016] P: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the P element content is below 0.03%, it cannot effectively improve the favorable crystal texture ratio; when the P element content is above 0.12%, it leads to a decrease in cold rolling stability. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage content of P element is controlled between 0.03% and 0.12%.

[0017] Al: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the Al content is higher than 0.4%, it significantly reduces the proportion of favorable grain texture and greatly deteriorates the magnetic induction of the steel. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of Al is controlled to be 0 < Al ≤ 0.4%.

[0018] Mg: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the Mg content is below 0.0002%, it is not conducive to controlling harmful inclusions in the steel; when the Mg content is above 0.004%, it leads to grain refinement and deterioration of iron loss. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of Mg is controlled between 0.0002% and 0.004%.

[0019] Cr: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the Cr content is below 0.01%, it is not conducive to reducing the iron loss of the finished steel sheet; when the Cr content is above 0.20%, it leads to a decrease in the proportion of favorable crystal texture. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of Cr is controlled between 0.01% and 0.20%.

[0020] In this invention, considering production costs, manufacturability, and the iron loss, magnetic induction, and cold rolling stability of non-oriented electrical steel sheets, the mass percentage of P+Cr is controlled to be 0.05% ≤ P+Cr ≤ 0.28%.

[0021] Furthermore, the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention also contains at least one of the following chemical elements in the following mass percentages:

[0022] 0 < Ge ≤ 0.01%;

[0023] 0 < Bi ≤ 0.01%;

[0024] 0 < Ca ≤ 0.01%;

[0025] 0 < REM ≤ 0.01%.

[0026] In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the design principles of the above-mentioned chemical elements are as follows:

[0027] Ge: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, Ge can significantly improve the proportion of favorable crystal texture. When the Ge content is higher than 0.01%, the manufacturing cost of the steel increases significantly. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage content of Ge is controlled to 0 < Ge ≤ 0.01%.

[0028] Bi: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, Bi can significantly improve the proportion of favorable crystal texture. When the Bi content is higher than 0.01%, it leads to severe grain refinement. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of Bi is controlled to be 0 < Bi ≤ 0.01%.

[0029] Ca: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, Ca can improve the cleanliness of the steel and promote grain growth. When the Ca content exceeds 0.01%, it leads to a significant increase in manufacturing costs. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of Ca is controlled to be 0 < Ca ≤ 0.01%.

[0030] REM: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, REM can improve the cleanliness of the steel and promote grain growth. When the REM content is higher than 0.01%, it will lead to a significant increase in manufacturing costs. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of REM is controlled to be 0 < REM ≤ 0.01%.

[0031] Furthermore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, it also contains at least one of Sn and Sb, and its mass percentage content satisfies: Sn: 0~0.20%, Sb: 0~0.10%, 0<Sn+Sb≤0.25%.

[0032] In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the design principles of the above-mentioned chemical elements are as follows:

[0033] Sn and Sb: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, Sn and Sb elements can promote favorable crystal texture growth, improve magnetic induction, and reduce iron loss. When Sn and Sb elements are added in excess, it leads to grain refinement and abnormal segregation. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of Sn is controlled between 0 and 0.20%, and the mass percentage of Sb is controlled between 0 and 0.10%. Furthermore, the total mass percentage of Sn and Sb can be controlled to be 0 < Sn + Sb ≤ 0.25%.

[0034] Furthermore, in the unavoidable impurities of the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the content of each impurity element satisfies at least one of the following: S≤0.003%, N≤0.003%, Ti≤0.001%.

[0035] In the above technical solution, S, N, and Ti are all impurity elements in steel. When technical conditions permit, to obtain steel with better performance and higher quality, the content of impurity elements in the steel should be reduced as much as possible. Specifically:

[0036] S: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the sulfur (S) content is higher than 0.003%, sulfide inclusions will increase significantly, inhibiting grain growth. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage of sulfur is controlled to S≤0.003%.

[0037] N: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the N element content is higher than 0.003%, it will significantly increase nitride inclusions and inhibit grain size growth. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage content of N element is controlled to N≤0.003%.

[0038] Ti: In the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, when the Ti content is higher than 0.001%, it significantly increases nitride inclusions and inhibits grain growth. Therefore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the mass percentage content of Ti is controlled to Ti ≤ 0.001%.

[0039] Furthermore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, the sulfide inclusions include composite MgS inclusions with MgS attached to the oxide matrix.

[0040] Furthermore, within the size range of 0.2–1.0 μm, the number of composite MgS inclusions accounts for 55%–75% of the total number of sulfide inclusions.

[0041] Furthermore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, its thickness is 0.35 to 0.65 mm.

[0042] Furthermore, in the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention, its magnetic induction B 5000 With iron loss P 1.5 / 50 The ratio is 0.6 to 0.74.

[0043] Another objective of this invention is to provide a method for manufacturing non-oriented electrical steel sheets. This method is based on the chemical composition design of this invention, optimizes the steel production process, increases the proportion of favorable crystal texture in the steel, and obtains non-oriented electrical steel sheets with excellent electromagnetic properties, good cold rolling properties, and higher cost performance.

[0044] To achieve the above objectives, the present invention provides a method for manufacturing non-oriented electrical steel sheets, comprising the following steps:

[0045] (1) Smelting and casting: Magnesium treatment is carried out during smelting;

[0046] (2) Heating and hot rolling;

[0047] (3) Cold rolling is performed after pickling;

[0048] (4) Continuous annealing: The heating rate is controlled at 50-1200℃ / s, the soaking time is 10-60s, and the soaking temperature is T=720+2000a[P+Cr], where the unit parameter of the soaking temperature T is ℃, [P+Cr] represents the value before the percentage sign of its mass content, and a represents the texture factor coefficient, which takes a range of a=0.6~1.5. The texture factor coefficient a is the ratio of crystal texture (111) / [(100)+(110)+(111)], which can be obtained by detecting the crystal texture of (100), (110), and (111) in the finished steel plate using X-RD (X-ray diffractometer) based on the national standard GB / T 40307-2021.

[0049] In this invention, the homogenization temperature of continuous annealing is related to the mass percentage of P+Cr in the chemical composition of the steel and the proportion of favorable crystal texture. The higher the mass percentage of P+Cr, the more favorable the growth of (100) and (110) textures, while suppressing the formation of (111) unfavorable textures. However, when the mass percentage of P+Cr is too high, it is easy to cause the clustering and segregation of fine grains, which is very detrimental to reducing the iron loss of the finished steel plate. Therefore, this invention adopts a high heating rate to quickly reach or exceed the region of unfavorable texture and fine grain formation, ensuring that in the high-temperature annealing stage after reaching the Curie temperature, the favorable texture and average grain size of the finished steel plate can be controlled by the reasonable design of the homogenization temperature, thereby obtaining a non-oriented electrical steel plate with coarse and well-developed microstructure, a high proportion of favorable crystal textures, and excellent electromagnetic properties.

[0050] Furthermore, between steps (2) and (3) of the method for manufacturing non-oriented electrical steel sheet according to the present invention, a normalization step is also included, wherein the normalization temperature is controlled to be 850-1000°C.

[0051] Furthermore, in step (2) of the method for manufacturing non-oriented electrical steel sheet according to the present invention, the furnace exit temperature of the billet is 1050-1200℃, the final rolling temperature is 800-1000℃, and the coiling temperature is 500-750℃.

[0052] Furthermore, in step (2) of the method for manufacturing non-oriented electrical steel sheet according to the present invention, the thickness of the hot-rolled sheet is 1.2 to 2.8 mm.

[0053] The non-oriented electrical steel sheet with excellent electromagnetic properties and its manufacturing method described in this invention have the following advantages and beneficial effects:

[0054] The non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention achieves excellent electromagnetic properties while also having good cold rolling processing performance and higher cost performance through reasonable design of chemical composition.

[0055] In some implementations, the magnetic induction B of the non-oriented electrical steel sheet 5000 With iron loss P 1.5 / 50 The ratio is 0.6 to 0.74.

[0056] The manufacturing method of the non-oriented electrical steel sheet with excellent electromagnetic properties described in this invention has significant advantages such as simplicity, ease of control, low cost, high precision, and ease of implementation. Attached Figure Description

[0057] Figure 1 The crystal texture of the non-oriented electrical steel sheet of Embodiment 1 of the present invention is shown.

[0058] Figure 2 The crystal texture of the comparative steel plate in Comparative Example 1 is shown.

[0059] Figure 3 The inclusion control effect of the non-oriented electrical steel sheet of Embodiment 3 of the present invention is shown.

[0060] Figure 4 The inclusion control effect of the comparative steel plate in Comparative Example 1 is shown.

[0061] Figure 5 The relationship between P+Cr content and magnetic induction B in non-oriented electrical steel sheets was shown. 5000 / Iron loss P 1.5 / 50 The relationship between them. Detailed Implementation

[0062] The following description, in conjunction with the accompanying drawings and specific embodiments, will further explain and illustrate the non-oriented electrical steel sheet with excellent electromagnetic properties and its manufacturing method as described in this invention. However, this explanation and description do not constitute an undue limitation on the technical solution of this invention.

[0063] Examples 1-7 and Comparative Examples 1-4

[0064] The non-oriented electrical steel sheets with excellent electromagnetic properties in Examples 1-7 of this invention and the comparative steels in Comparative Examples 1-4 were all prepared using the following steps:

[0065] (1) Smelting and casting: The raw materials for steelmaking are blast furnace iron or high-quality scrap steel, or a combination of blast furnace iron and high-quality scrap steel in a certain proportion. The steelmaking technology is converter steelmaking and continuous casting, or electric furnace steelmaking and continuous casting. The chemical composition design is shown in Tables 1-1 and 1-2. In addition, magnesium treatment can be carried out to obtain a suitable inclusion control effect;

[0066] (2) Heating and hot rolling: The furnace exit temperature of the billet can be controlled at 1050-1200℃, the final rolling temperature can be controlled at 800-1000℃, and the coiling temperature can be controlled at 500-750℃; the thickness of the hot-rolled plate obtained is 1.2-2.8mm; then step (4) can be carried out directly, or step (4) can be carried out after step (3);

[0067] (3) Normalizing and bell-type furnace annealing: The normalizing temperature can be controlled at 850-1000℃;

[0068] (4) Cold rolling after pickling: After pickling, cold rolling is carried out using a cold continuous rolling mill or a reciprocating rolling mill. The target thickness of the cold-rolled non-oriented electrical steel sheet can be controlled to be 0.35 to 0.50 mm.

[0069] (5) Continuous annealing: control the heating rate to be 50~1200℃ / s, the soaking time to be 10~60s, and the soaking temperature to be T=720+2000a[P+Cr], where the unit parameter of the soaking temperature T is ℃, [P+Cr] represents the value before the percentage sign of its mass percentage content, and a represents the texture factor coefficient, the value range of a=0.6~1.5.

[0070] Tables 1-1 and 1-2 list the mass percentage of each chemical element in the non-oriented electrical steel sheets with excellent electromagnetic properties of Examples 1-9 of the present invention and the comparative steels of Comparative Examples 1-4.

[0071] Table 1-1. (wt%, balance Fe and other unavoidable impurities other than S, N, and Ti)

[0072]

[0073]

[0074] Table 1-2. (wt%, balance Fe and other unavoidable impurities besides S, N, and Ti)

[0075] serial number Ge Bi Ca REM Sb Sn Sn+Sb S N Ti Example 1 0 0 0 0 0 0.03 0.03 0.0021 0.0018 0.0002 Example 2 0.01 0 0 0.01 0.03 0 0.03 0.0030 0.0030 0.0010 Example 3 0 0 0 0 0 0.10 0.1 0.0025 0.0012 0.0005 Example 4 0 0.01 0.01 0 0.10 0 0.1 0.0018 0.0024 0.0010 Example 5 0 0 0 0 0 0.17 0.17 0.0007 0.0008 0.0008 Example 6 0 0 0 0 0 0.10 0.1 0.0028 0.0012 0.0003 Example 7 0 0 0 0 0.05 0.20 0.25 0.0016 0.0020 0.0005 Example 8 0 0 0 0 0 0 0 0.0020 0.0015 0.0009 Example 9 0.01 0.01 0 0 0 0 0 0.0010 0.0010 0.0005 Comparative Example 1 0 0 0.002 0 0 0.02 0.02 0.0035 0.0013 0.0005 Comparative Example 2 0 0 0.004 0 0 0 0 0.0026 0.0028 0.0005 Comparative Example 3 0 0 0 0 0.10 0 0.1 0.0006 0.0007 0.0016 Comparative Example 4 0 0 0 0 0 0.05 0.05 0.0015 0.0016 0.0005

[0076] Tables 2-1 and 2-2 list the specific process parameters of the non-oriented electrical steel sheets with excellent electromagnetic properties in Examples 1-9 of the present invention and the comparative steels in Comparative Examples 1-4.

[0077] Table 2-1.

[0078]

[0079] Note: In the table above, “√” indicates good cold rolling rollability, with no issues such as strip breakage, edge cracking, sheet shape problems, or speed reduction affecting production stability. “×” indicates poor cold rolling rollability, with one or more of the following issues: strip breakage, edge cracking, sheet shape problems, or speed reduction.

[0080] Among them, the analysis and testing of inclusions used SEM+EDS to continuously observe 200 fields of view, detect the elemental composition and proportion of inclusions, and count the types, sizes and quantities of inclusions.

[0081] Table 2-2.

[0082]

[0083] Note: Based on the national standard GB / T 40307-2021, X-RD (X-ray diffractometer) was used to detect the crystal texture of (100), (110), and (111) in the finished steel plate to obtain the texture factor coefficient a of each embodiment and comparative example.

[0084] also, Figure 1 The crystal texture of Embodiment 1 of the present invention is shown. Figure 2 The crystal texture of the comparative steel plate in Comparative Example 1 is shown.

[0085] like Figure 1 and Figure 2 As shown, there are significant differences between Example 1 and Comparative Example 1 in the content of (100), (110), and (111) textures. In Example 1, the content of (100) and (110) favorable textures is significantly higher, while the content of (111) unfavorable textures is lower, whereas Comparative Example 1 is the opposite.

[0086] In addition, samples were taken from the finished product samples of Example 3 and Comparative Example 1. Figure 3 The effect of inclusion control in Embodiment 3 of the present invention is shown. Figure 4 The effect of inclusion control in Comparative Example 1 is shown.

[0087] like Figure 3 and Figure 4As shown, in Example 3, after magnesium treatment, Mg and S fully combine to form large, low-density MgS composite inclusions, which are easily floated and removed. Therefore, the steel has high cleanliness, which is beneficial for forming a good crystal texture and promoting uniform grain growth. At the same time, the number and size of residual harmful inclusions in the steel are small, having little impact. In contrast, Comparative Example 1, without magnesium treatment, has a large number and small size of sulfide inclusions in the steel, which easily pin grain boundaries, hindering magnetic domain rotation and domain wall movement, thus negatively impacting good crystal texture growth and grain size development.

[0088] In this invention, the sulfide inclusions are mainly composed of individual MgS particles and composite MgS inclusions with individual MgS particles attached to an oxide matrix, with a small amount of MgS+AlN inclusions also present. The individual MgS inclusions are spherical or near-spherical in shape.

[0089] Samples of the non-oriented electrical steel sheets with excellent electromagnetic properties obtained in Examples 1-9 and the comparative steel sheets in Comparative Examples 1-4 were taken, and various relevant properties were tested on the samples of each example and comparative example steel sheet. The results of the relevant performance tests are listed in Table 3. The specific testing methods for the relevant performance are as follows:

[0090] Iron loss performance testing: Based on the national standard GB / T 3658-1990, the Epstein square method was used to test the iron loss performance. The test temperature was a constant temperature of 20℃, the sample size was 30mm×300mm, the target mass was 0.5kg, and the test parameter was P. 1.5 / 50 .

[0091] Magnetic performance testing: Based on national standard GB / T 3658-1990, the Epstein square ring method was used to test iron loss performance. The test temperature was a constant temperature of 20℃, the sample size was 30mm × 300mm, the target mass was 0.5kg, and the test parameter was B. 5000 .

[0092] Table 3 lists the test results of the electromagnetic properties of the non-oriented electrical steel sheets of Examples 1-9 and the comparative steels of Examples 1-4, which are excellent in electromagnetic properties according to the present invention.

[0093] Table 3.

[0094]

[0095] As can be seen from Table 3, the magnetic induction B of the non-oriented electrical steel sheets in Examples 1-9 5000 With iron loss P 1.5 / 50The ratios were all between 0.62 and 0.74, indicating that the effective increase in P+Cr content improved the (100) and (110) crystal texture of the sample, thereby increasing magnetic induction and reducing iron loss, and maintaining a good ratio between the two. In addition, as can be seen from Table 2-1, the cold rolling workability of each embodiment of the present invention is good.

[0096] also, Figure 5 This invention demonstrates the relationship between the P+Cr content and the magnetic induction B in the non-oriented electrical steel sheet with excellent electromagnetic properties. 5000 / Iron loss P 1.5 / 50 The relationship between them.

[0097] like Figure 5 As shown, when the P+Cr content is below 0.05% or above 0.28%, the magnetic induction B... 5000 / Iron loss P 1.5 / 50 All values ​​were below 0.60, which is not conducive to improving the crystal texture ratio of (100) and (110). Meanwhile, with the increase of P+Cr content, the magnetic induction B... 5000 / Iron loss P 1.5 / 50 It can be rapidly improved, and good magnetic induction B is maintained within the range of 0.05% to 0.28%. 5000 / Iron loss P 1.5 / 50 .

[0098] The Mg content of Comparative Example 1 was 0.0001%, which is lower than the design limit of 0.0002%. Furthermore, Comparative Example 1 experienced strip breakage during cold rolling at a normalizing temperature of 950°C, affecting its rollability. Additionally, the iron loss P of Comparative Example 1... 1.5 / 50 Higher, magnetic induction B 5000 Lower, magnetic induction B 5000 and iron loss P 1.5 / 50 The ratio is 0.56.

[0099] Comparative Example 2 had a P+Cr content of 0.30%, exceeding the design limit of 0.28%, which caused strip breakage during cold rolling, affecting rollability. Furthermore, in Comparative Example 2, during continuous annealing, α was 0.4, outside the range of 0.6–1.5, corresponding to a soaking temperature of 960℃, lower than the design requirements of the invention. Additionally, the iron loss P in Comparative Example 2… 1.5 / 50 Higher, magnetic induction B 5000 Lower, magnetic induction B 5000 and iron loss P 1.5 / 50 The ratio is 0.58.

[0100] Comparative Example 3 has an Al content of 0.55%, which is 0.4% higher than the design upper limit; a P content of 0.02%, which is 0.03% lower than the design lower limit; and a P+Cr content of 0.04%, which is 0.05% lower than the invention's design lower limit. Meanwhile, the continuous annealing heating rate of Comparative Example 3 is 15℃ / s, lower than the invention's design lower limit of 50℃ / s; and the soaking temperature is 850℃, outside the design range of 768–840℃ corresponding to a (0.6–1.5). Correspondingly, the iron loss P of the comparative steel of Comparative Example 3 is... 1.5 / 50 Higher, magnetic induction B 5000 Lower, magnetic induction B 5000 and iron loss P 1.5 / 50 The ratio is 0.59.

[0101] The Mg content of Comparative Example 4 was only 0.0001%, lower than the design lower limit of 0.0002%. Simultaneously, the continuous annealing heating rate of Comparative Example 4 was 40℃ / s, lower than the design lower limit of 50℃ / s, and the soaking time was 5s, lower than the design lower limit of 10s. Correspondingly, the iron loss P of the comparative steel obtained in Comparative Example 4 was lower than that of the steel in this invention. 1.5 / 50 Higher, magnetic induction B 5000 Lower, magnetic induction B 5000 and iron loss P 1.5 / 50 The ratio is 0.55.

[0102] It should be noted that the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0103] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A non-oriented electrical steel sheet with excellent electromagnetic properties, containing Fe and unavoidable impurities, characterized in that, It also contains the following chemical elements in the following percentages by mass: 0<C≤0.003%, Si: 1.2~2.4%, Mn: 0.05~0.5%, P: 0.03~0.12%, 0<Al≤0.4%, Mg: 0.0002~0.004%, Cr: 0.01~0.20%; The mass percentage of P+Cr is 0.05%–0.28%.

2. The non-oriented electrical steel sheet as described in claim 1, characterized in that, Its mass percentage content of each chemical element is as follows: 0 < C ≤ 0.003%, Si: 1.2–2.4%, Mn: 0.05–0.5%, P: 0.03–0.12%, 0 < Al ≤ 0.4%, Mg: 0.0002–0.004%, Cr: 0.01–0.20%; balance is Fe and unavoidable impurities. The mass percentage of P+Cr is 0.05%–0.28%.

3. The non-oriented electrical steel sheet as described in claim 1 or 2, characterized in that, It also contains at least one of the following chemical elements in the following mass percentages: 0 < Ge ≤ 0.01%; 0 < Bi ≤ 0.01%; 0 < Ca ≤ 0.01%; 0 < REM ≤ 0.01%.

4. The non-oriented electrical steel sheet as described in claim 1 or 2, characterized in that, It also contains at least one of Sn and Sb, and its mass percentage content satisfies: Sn: 0 to 0.20%, Sb: 0 to 0.10%, 0 < Sn + Sb ≤ 0.25%.

5. The non-oriented electrical steel sheet as described in claim 1 or 2, characterized in that, Among the unavoidable impurities, the content of each impurity element must satisfy at least one of the following conditions: S≤0.003%, N≤0.003%, Ti≤0.001%.

6. The non-oriented electrical steel sheet as described in claim 1 or 2, characterized in that, Its sulfide inclusions include complex MgS inclusions with MgS attached to the oxide matrix.

7. The non-oriented electrical steel sheet as described in claim 6, characterized in that, Within the size range of 0.2–1.0 μm, the number of composite MgS inclusions accounts for 55%–75% of the total number of sulfide inclusions.

8. The non-oriented electrical steel sheet as described in claim 1 or 2, characterized in that, Its thickness is 0.35 to 0.65 mm.

9. The non-oriented electrical steel sheet as described in claim 1 or 2, characterized in that, Its magnetic induction B 5000 With iron loss P 1.5 / 50 The ratio is 0.6 to 0.

74.

10. A method for manufacturing non-oriented electrical steel sheet according to any one of claims 1-9, characterized in that, Including the following steps: (1) Smelting and casting: Magnesium treatment is carried out during smelting; (2) Heating and hot rolling; (3) Cold rolling is performed after pickling; (4) Continuous annealing: The heating rate is controlled at 50-1200℃ / s, the soaking time is 10-60s, and the soaking temperature is T=720+2000a[P+Cr], where the unit parameter of the soaking temperature T is ℃, [P+Cr] represents the value before the percentage sign of its mass percentage content, and a represents the texture factor coefficient, which takes a range of a=0.6~1.

5.

11. The manufacturing method as described in claim 10, characterized in that, Between steps (2) and (3), there is also a normalization step, with the normalization temperature controlled at 850 to 1000°C.

12. The manufacturing method as described in claim 10, characterized in that, In step (2), the furnace exit temperature of the billet is 1050-1200℃, the final rolling temperature is 800-1000℃, and the coiling temperature is 500-750℃.

13. The manufacturing method as described in claim 10, characterized in that, In step (2), the thickness of the hot-rolled plate is 1.2 to 2.8 mm.

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