Non-oriented electrical steel plate and manufacturing method therefor
By optimizing the chemical composition and production process of non-oriented electrical steel sheets, the problems of low iron loss, high magnetic induction, and high strength of electrical steel sheets under low-carbon metallurgical processes have been solved, achieving cost-effective electromagnetic and mechanical properties and strong applicability in steel sheet manufacturing.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- BAOSHAN IRON & STEEL CO LTD
- Filing Date
- 2025-12-05
- Publication Date
- 2026-06-18
AI Technical Summary
Existing non-oriented electrical steel sheets cannot simultaneously possess the characteristics of low iron loss, high magnetic induction, and high strength under low-carbon metallurgical processes, and their processing costs are high and their applicability is insufficient.
By optimizing the chemical composition design and production process route, controlling the content of chemical elements such as C, Si, Mn, P, Al, Ni, and Cr, and combining magnesium treatment, calcium treatment, and rare earth treatment, and adopting processes such as bell-type furnace annealing, cold rolling, and continuous annealing, the electromagnetic and mechanical properties of steel plates are optimized.
It achieves low iron loss, high magnetic induction and high strength of non-oriented electrical steel sheets under low carbon metallurgical process, is easy to process, has high cost performance, strong applicability and good microstructure uniformity.
Smart Images
Figure CN2025140396_18062026_PF_FP_ABST
Abstract
Description
A non-oriented electrical steel sheet and its manufacturing method Technical Field
[0001] This disclosure 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] With the increasing demand for energy conservation, carbon reduction, environmental protection, and high efficiency, there is a desire for non-oriented electrical steel sheets to simultaneously possess the characteristics of low iron loss, high magnetic induction, and high strength under low-carbon metallurgical processes. Existing patent literature has explored related approaches to improve the electromagnetic and mechanical properties of electrical steel sheets.
[0003] For example, Chinese patent document CN103498096A (publication date: January 8, 2014, entitled "Excellent Magnetic Performance Non-oriented Electrical Steel with Rm≥600MPa and its Production Method") discloses an excellent magnetic performance non-oriented electrical steel with Rm≥600MPa. Its chemical composition (by weight percentage) includes: Si: 2.5~3.5%, Mn: 0.1~1.0%, Ni+Al not exceeding 1.0%, N≤0.005%, S≤0.015%, C≤0.003%, P≤0.05%, with the remainder being iron and residual content. Furthermore, this document also requires that the following relationships be met: 1.0≤Al / Ni≤2.0, C+S+N≤0.007. The production method disclosed in this document includes the following steps: smelting and casting the billet in a converter; subsequently heating the continuously cast billet to a temperature not lower than 1050℃, and holding the hot-rolled billet in the furnace for not less than 120 minutes; hot rolling, wherein the roughing rolling temperature is not lower than 900℃ and the steel plate thickness is not lower than 25mm; finishing rolling, wherein the finishing rolling temperature is not lower than 750℃ and the plate thickness is not lower than 2.0mm; coiling, wherein the coiling temperature is not lower than 700℃; and normalizing, wherein the normalizing homogenization temperature is not lower than 750℃. The temperature is ℃, and the normalizing time is not less than 1 minute; after the normalized steel coil is pickled, it is cold rolled. The pickling temperature is 60-100℃, and the pickling time is 2-5 minutes. Cold rolling is carried out by one-pass cold rolling with 4-7 rolling passes. The total reduction rate of the first 3-6 passes is controlled to be not less than 80%, and the reduction rate of any single pass does not exceed 20%; then, continuous annealing is carried out. The annealing temperature is not less than 850℃, the soaking time is not less than 1 minute, the atmosphere is a conventional H2+N2 mixture, N2 / H2≤0.5, and the gas flow rate is not less than 200m³ / h. 3 The steel was cooled naturally to room temperature at a speed of [speed in kilometer] / min. This method ultimately yielded a finished steel coil with a thickness of 0.35 mm, exhibiting mechanical properties Rm ≥ 600 MPa, ReL ≥ 500 MPa, and iron loss P [value missing]. 1.0 / 400 ≤17W / kg, magnetic induction B 5000 ≥1.66T.
[0004] For example, Chinese patent document CN101821418A (publication date: September 1, 2010, entitled "High-Frequency Non-directional Electromagnetic Steel Plate with Low Iron Loss and its Manufacturing Method") discloses a high-frequency non-directional electromagnetic steel plate with low iron loss and its manufacturing method. The chemical composition (by mass%) of the steel plate includes: C: less than 0.005%, Si: 2.0% to 4.0%, Mn: less than 1%, and Al: 0.1% to 8.0%, with the remainder including Fe and unavoidable impurities. Furthermore, the Al concentration in the thickness direction is required to satisfy 0.1 < (Xs - Xc) < 100. To further improve the electromagnetic performance, this document also proposes the addition of one or more of the following elements: Cu ≤ 5%, Nb ≤ 1%, Ti ≤ 1%, Ni ≤ 5%, Cr ≤ 15%; and one or more of Mo, W, Sn, Mg, Ce, etc., with the addition amount not exceeding 0.5%. After hot rolling, the literature describes coating the steel strip surface with an Al-containing coating using vapor deposition or hot dipping; the steel strip is then cold rolled to 0.1–0.3 mm; and finally annealed at 1000°C for more than 1 hour. Summary of the Invention
[0005] One of the objectives of this disclosure is to provide a non-oriented electrical steel sheet. This non-oriented electrical steel sheet, through optimized chemical composition design, can simultaneously achieve excellent electromagnetic and mechanical properties, and is characterized by convenient processing, strong applicability, and high cost-effectiveness.
[0006] To achieve the above objectives, this disclosure provides a non-oriented electrical steel sheet, which, in addition to containing Fe and unavoidable impurities, also contains the following chemical elements in the following mass percentages:
[0007] 0 < C ≤ 0.0040%, preferably C: 0.0007-0.0040%; Si: 2.0-3.6%; Mn: 0.05-2.00%, preferably Mn: 0.24-2.00%; P: 0.02-0.12%; 0 < Al ≤ 2.00%, preferably Al: 0.10-2.00%; 0 < Mg ≤ 0.0050%; Ni: 0.01-0.50%, preferably Ni: 0.10-0.50%; Cr: 0.01-0.50%, preferably Cr: 0.10-0.50%.
[0008] Preferably, the mass percentage content of each chemical element in the non-oriented electrical steel sheet of this disclosure is as follows:
[0009] 0 < C ≤ 0.0040%, preferably C: 0.0007-0.0040%; Si: 2.0-3.6%; Mn: 0.05-2.00%, preferably Mn: 0.24-2.00%; P: 0.02-0.12%; 0 < Al ≤ 2.00%, preferably Al: 0.10-2.00%; 0 < Mg ≤ 0.0050%; Ni: 0.01-0.50%, preferably Ni: 0.10-0.50%; Cr: 0.01-0.50%, preferably Cr: 0.10-0.50%; the balance is Fe and unavoidable impurities.
[0010] Preferably, unavoidable impurities include S, N, and Ti, with S ≤ 0.0030%, N ≤ 0.0030%, and Ti ≤ 0.0020%.
[0011] Preferably, in the non-oriented electrical steel sheet of this disclosure, the total amount of Si and Al (Si+Al) is 3.2% to 4.6%.
[0012] Considering manufacturability, manufacturing cost, electromagnetic properties, and cold-rolling stability of non-oriented electrical steel sheets, a more preferable total amount of Si and Al is: 3.2% ≤ Si + Al ≤ 4.6%.
[0013] Preferably, the non-oriented electrical steel sheet of this disclosure further contains at least one of the following chemical elements in mass percentage:
[0014] 0 < Ca ≤ 0.005%;
[0015] 0 < REM ≤ 0.005%.
[0016] Preferably, the non-oriented electrical steel sheet of this disclosure further 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%.
[0017] Preferably, the average grain size of the non-oriented electrical steel sheet disclosed herein before stress-relief annealing is 25-60 μm.
[0018] Preferably, the average grain size of the non-oriented electrical steel sheet disclosed herein after stress-relief annealing is 100-175 μm.
[0019] Preferably, the non-oriented electrical steel sheet of this disclosure has a fully recrystallized structure after stress-relief annealing, and the ratio (B / A) of the average grain size (B) after stress-relief annealing to the average grain size (A) before stress-relief annealing is 2.5 to 5.0.
[0020] Preferably, in the non-oriented electrical steel sheet of this disclosure, the number of inclusions with an average size between 300-800 nm in the steel sheet after stress-relief annealing is ≤4.8 × 10⁻⁶. 6 / mm 3 .
[0021] Preferably, in the non-oriented electrical steel sheet of this disclosure, the amount of inclusions in the steel sheet after stress-relief annealing satisfies: 3.3% ≤ oxide inclusions / (oxide inclusions + sulfide inclusions + nitride inclusions) ≤ 8.1%.
[0022] Preferably, the thickness of the non-oriented electrical steel sheet disclosed herein is 0.15 to 0.35 mm.
[0023] Preferably, the yield strength Y of the non-oriented electrical steel sheet of this disclosure before stress-relief annealing is... S ≥500MPa.
[0024] Preferably, the iron loss P of the non-oriented electrical steel sheet of this disclosure after stress-relief annealing is... 1.0 / 400 ≤11.5W / kg, magnetic induction B 5000 ≥1.65T.
[0025] Another object of this disclosure is to provide a method for manufacturing non-oriented electrical steel sheets. This method is based on the chemical composition design of this disclosure and optimizes the production process to give the steel sheets excellent electromagnetic and mechanical properties, while also being easy to process, highly adaptable, and cost-effective.
[0026] To achieve the above objectives, this disclosure provides a method for manufacturing a non-oriented electrical steel sheet, comprising the following steps:
[0027] (1) Smelting and casting;
[0028] (2) Heating and hot rolling;
[0029] (3) Normalizing and bell-type furnace annealing: The soaking temperature for normalizing and bell-type furnace annealing is 850-1000℃, and the soaking time is 60-300s;
[0030] (4) Cold rolling;
[0031] (5) Continuous annealing: The soaking temperature for continuous annealing is 700-1050℃ and the soaking time is 5-60s.
[0032] Preferably, magnesium treatment can be performed during smelting, and calcium and / or rare earth treatment can also be performed as needed.
[0033] Preferably, in step (2) of the manufacturing method disclosed herein, the furnace exit temperature of the billet is 1050-1200°C, the final rolling temperature is 800-1000°C, and the coiling temperature is 500-800°C.
[0034] Preferably, pickling is performed before cold rolling.
[0035] Preferably, the manufacturing method disclosed herein further includes step (6) stress-relief annealing, wherein the soaking temperature for stress-relief annealing is T. 均热 =T 再结晶开始温度 +(80~155℃).
[0036] The non-oriented electrical steel sheet and its manufacturing method disclosed herein have the following advantages and beneficial effects:
[0037] The non-oriented electrical steel sheet disclosed herein, through optimized chemical composition design, can simultaneously obtain excellent electromagnetic and mechanical properties, and is easy to process, highly applicable, and cost-effective.
[0038] In some embodiments, the yield strength Y of the non-oriented electrical steel sheet of this disclosure before stress-relief annealing is... S ≥500MPa, after stress-relief annealing, the iron loss P in the rolling direction and perpendicular to the rolling direction. 1.0 / 400 All values are ≤11.5W / kg, thus possessing both excellent mechanical and electromagnetic properties.
[0039] The manufacturing method disclosed herein is simple to operate, easy to control, low in cost, high in precision, and easy to implement industrially. Attached Figure Description
[0040] Figure 1 shows the microstructure of the non-oriented electrical steel sheet of Example 1 before stress-relief annealing.
[0041] Figure 2 shows the microstructure of the comparative steel sheet of Comparative Example 1 before stress-relief annealing.
[0042] Figure 3 shows the inclusion morphology of the non-oriented electrical steel sheet of Example 3.
[0043] Figure 4 shows the inclusion morphology of the comparative steel plate of Comparative Example 3. Detailed Implementation
[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.
[0045] In this paper, microstructures were observed using metallographic microscopy or optical microscopy.
[0046] In this paper, the average grain size was determined according to GB / T 6394-2017 "Method for determination of average grain size of metals".
[0047] In this paper, the size, quantity, and proportion of inclusions were determined according to GB T10561-2005 "Determination of Non-metallic Inclusion Content in Steel - Standard Rating Chart Microscopic Examination Method".
[0048] In this paper, the yield strength Y S Determined according to GB / T 228.1-2010.
[0049] In this paper, iron loss P 1.0 / 400 (Iron loss measured under conditions of magnetic flux density 1.0T and frequency 400Hz) and magnetic induction B 5000 The determination was performed using the Epstein square circle method according to GB / T 3655-2008.
[0050] The design principles of each chemical element in the non-oriented electrical steel sheet disclosed herein are as follows:
[0051] C: In the non-oriented electrical steel sheet of this disclosure, adding an appropriate amount of carbon (C) can improve the strength of the finished steel sheet and facilitate the stamping process. However, when the mass percentage of C exceeds 0.0040%, it will cause magnetic aging and degrade the electromagnetic properties of the steel. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of C is controlled to be 0 < C ≤ 0.0040%, preferably 0.0007-0.0040%.
[0052] Si: In the non-oriented electrical steel sheet of this disclosure, when the mass percentage of Si is less than 2.0%, the iron loss of the steel cannot be effectively reduced; when the mass percentage of Si is greater than 3.6%, the cold rolling stability will be significantly reduced. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of Si is controlled between 2.0% and 3.6%.
[0053] Mn: In the non-oriented electrical steel sheet of this disclosure, when the mass percentage of Mn is less than 0.05%, surface defects of the cast billet are easily formed; when the mass percentage of Mn is greater than 2.00%, the manufacturing cost of the steel will increase significantly. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of Mn is controlled between 0.05% and 2.00%, preferably between 0.24% and 2.00%.
[0054] P: In the non-oriented electrical steel sheet of this disclosure, when the mass percentage of P element is less than 0.02%, it cannot effectively improve the favorable crystal texture ratio; when the mass percentage of P element is greater than 0.12%, it leads to a decrease in cold rolling stability. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of P element is controlled between 0.02% and 0.12%.
[0055] Al: In the non-oriented electrical steel sheet of this disclosure, Al can increase the resistivity of the material. Adding an appropriate amount of Al to the steel is beneficial for reducing material loss. However, when the mass percentage of Al exceeds 2.00%, it significantly reduces the favorable grain texture ratio and greatly degrades the magnetic induction of the steel. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of Al is controlled to be 0 < Al ≤ 2.00%, preferably 0.10-2.00%.
[0056] Mg: In the non-oriented electrical steel sheet of this disclosure, Mg has a strong affinity for O and S elements, which can generate coarse composite inclusions and facilitate their flotation and removal, thus improving the cleanliness of the material. However, when the mass percentage of Mg exceeds 0.0050%, it leads to grain refinement and deterioration of iron loss. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of Mg is controlled to be 0 < Mg ≤ 0.0050%.
[0057] Ni: In the non-oriented electrical steel sheet of this disclosure, when the mass percentage of Ni is less than 0.01%, it is not conducive to improving the magnetic induction of the finished steel sheet; when the mass percentage of Ni is greater than 0.50%, it leads to grain refinement and deterioration of iron loss. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of Ni is controlled between 0.01% and 0.50%, preferably 0.10% to 0.50%.
[0058] Cr: In the non-oriented electrical steel sheet of this disclosure, when the mass percentage of Cr is less than 0.01%, it is not conducive to reducing the iron loss of the finished steel sheet; when the mass percentage of Cr is greater than 0.50%, it leads to a decrease in the proportion of favorable crystal texture. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of Cr is controlled between 0.01% and 0.50%, preferably between 0.10% and 0.50%.
[0059] In the non-oriented electrical steel sheet disclosed herein, S, N, and Ti are all impurity elements in the steel. Where technical conditions permit, to obtain steel with better performance and superior quality, the content of impurity elements in the steel should be reduced as much as possible, wherein:
[0060] S: In the non-oriented electrical steel sheet of this disclosure, when the sulfur (S) content is higher than 0.0030%, sulfide inclusions are significantly increased, inhibiting grain growth. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of sulfur is controlled to S≤0.0030%.
[0061] N: In the non-oriented electrical steel sheet of this disclosure, when the N element content is higher than 0.0030%, it will significantly increase nitride inclusions and inhibit grain size growth. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage content of N element is controlled to N≤0.0030%.
[0062] Ti: In the non-oriented electrical steel sheet of this disclosure, when the Ti content is higher than 0.0020%, it significantly increases nitride inclusions and inhibits grain growth. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage content of Ti is controlled to Ti ≤ 0.0020%.
[0063] In addition, to obtain better performance, the non-oriented electrical steel sheet disclosed herein may also contain any one of Ca, REM (rare earth elements), Sn and Sb.
[0064] Ca: In the non-oriented electrical steel sheet of this disclosure, Ca can improve the cleanliness of the steel and promote grain growth. However, when the mass percentage of Ca exceeds 0.005%, it leads to a significant increase in manufacturing costs. Therefore, in the non-oriented electrical steel sheet of this disclosure, the preferred mass percentage of Ca is 0 < Ca ≤ 0.005%.
[0065] REM: In the non-oriented electrical steel sheet of this disclosure, REM can improve the cleanliness of the steel and promote grain growth. However, when the mass percentage of REM element exceeds 0.005%, it leads to a significant increase in the manufacturing cost of the steel. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage of REM element is preferably 0 < REM ≤ 0.005%.
[0066] Sn and Sb: In the non-oriented electrical steel sheet of this disclosure, Sn and Sb elements can promote favorable crystal texture growth and improve magnetic induction while reducing iron loss. However, when the content of Sn and Sb elements is excessive, it can lead to grain refinement and abnormal segregation. Therefore, in the non-oriented electrical steel sheet of this disclosure, the mass percentage content of Sn element is preferably 0 to 0.20%, and the mass percentage content of Sb element is preferably between 0 and 0.10%. Furthermore, it is also preferred that the sum of the mass percentage contents of Sn and Sb elements satisfies 0 < Sn + Sb ≤ 0.25%.
[0067] In some embodiments, the method for manufacturing the non-oriented electrical steel sheet of this disclosure includes the following steps:
[0068] (1) Smelting and casting;
[0069] (2) Heating and hot rolling;
[0070] (3) Normalizing and bell-type furnace annealing: The soaking temperature for normalizing and bell-type furnace annealing is 850-1000℃, and the soaking time is 60-300s;
[0071] (4) Cold rolling;
[0072] (5) Continuous annealing: The soaking temperature for continuous annealing is 700-1050℃ and the soaking time is 5-60s.
[0073] In some implementations, the steelmaking raw materials used in step (1) are blast furnace iron, high-quality scrap steel, or a combination of the two in a certain proportion. In some implementations, the steelmaking technology used in step (1) is converter steelmaking and continuous casting, or electric furnace steelmaking and continuous casting.
[0074] In some implementations, 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 500-800℃, to obtain a hot-rolled plate with a thickness of 1.2-2.8mm.
[0075] In some implementations, in step (3), the normalizing and bell-type furnace annealing are performed at a homogenization temperature of 850–1000°C for 60–300 s.
[0076] In some implementations, pickling is performed after step (3), followed by cold rolling using a cold continuous rolling mill or a reciprocating rolling mill.
[0077] In some implementations, when performing step (4) cold rolling, the target thickness can be achieved by cold rolling in one go, or by cold rolling in one go + intermediate annealing + cold rolling in two go to the target thickness.
[0078] In some implementation schemes, the target thickness of the cold-rolled non-oriented electrical steel sheet can be 0.15 to 0.35 mm.
[0079] In some implementations, in step (5), the soaking temperature of continuous annealing is 700-1050°C, preferably 750-950°C, and the soaking time is 5-60s, preferably 8-45s.
[0080] In some embodiments, the manufacturing method of this disclosure further includes step (6) stress-relief annealing, wherein the soaking temperature for stress-relief annealing is T. 均热 =T 再结晶开始温度 +(80~155℃).
[0081] In some preferred embodiments, in step (6), the soaking temperature for stress-relief annealing is T. 均热 =T 再结晶开始温度 +(100~135℃).
[0082] The non-oriented electrical steel sheet and its manufacturing method disclosed herein will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, such explanation and description do not constitute an improper limitation on the technical solution of the present invention.
[0083] Examples 1-8 and Comparative Examples 1-3
[0084] The non-oriented electrical steel sheets of Examples 1-8 and the comparative steel sheets of Comparative Examples 1-3 were all prepared using the following steps:
[0085] (1) Smelting and casting;
[0086] (2) Heating and hot rolling;
[0087] (3) Normalizing and bell-type furnace annealing;
[0088] (4) Cold rolling;
[0089] (5) Continuous annealing;
[0090] (6) Stress-relief annealing.
[0091] Tables 1-1 and 1-2 list the mass percentage of each chemical element in the non-oriented electrical steel sheets of Examples 1-8 and the comparative steels of Comparative Examples 1-3.
[0092] Table 1-1. (wt%, balance Fe and other unavoidable impurities other than S, N, and Ti)
[0093] Table 1-2. (wt%, balance Fe and other unavoidable impurities besides S, N, and Ti)
[0094] Table 2 lists the specific process parameters in the preparation methods of the non-oriented electrical steel sheets of Examples 1-8 and the comparative steels of Comparative Examples 1-3.
[0095] Samples of the non-oriented electrical steel sheets of Examples 1-8 and the control steels of Comparative Examples 1-3 were taken before and after stress-relief annealing. The microstructure of each example and comparative example was observed, and the results of the microstructure observations before and after stress-relief annealing are listed in Table 3. Wherein:
[0096] Microstructure: The cross-sectional microstructure perpendicular to the rolling direction of the steel plate was observed using a metallographic / optical microscope at a magnification of X50 to X200.
[0097] Average grain size: The average grain size in the cross-section of the steel plate perpendicular to the rolling direction is measured according to GB / T 6394-2017 "Method for determination of average grain size of metal".
[0098] Inclusions: The types and quantities of inclusions in finished steel plates or samples are determined in accordance with GB T10561-2005 "Determination of Non-metallic Inclusion Content in Steel - Standard Rating Chart Microscopic Examination Method".
[0099] Table 3 lists the results of microstructure observations of the non-oriented electrical steel sheets of Examples 1-8 and the control steels of Comparative Examples 1-3 before and after stress-relief annealing.
[0100] Table 3.
[0101] As can be seen from Table 3 above, the microstructure of the non-oriented electrical steel sheets in Examples 1-8 after stress-relief annealing is a fully recrystallized microstructure. Furthermore, the ratio (B / A) of the average grain size after stress-relief annealing to the average grain size before stress-relief annealing is between 2.5 and 5.0. The number of inclusions with an average size between 300-800 nm in the steel sheets after stress-relief annealing is ≤4.8 × 10⁻⁶. 6 / mm 3 Furthermore, the amount of inclusions in the steel plate after stress-relief annealing satisfies the following condition: 3.3% ≤ oxide inclusions / (oxide inclusions + sulfide inclusions + nitride inclusions) ≤ 8.1%.
[0102] Figure 1 shows the microstructure of the non-oriented electrical steel sheet of Example 1 before stress-relief annealing.
[0103] Figure 2 shows the microstructure of the comparative steel sheet of Comparative Example 1 before stress-relief annealing.
[0104] As shown in Figures 1 and 2, the microstructures of Example 1 and Comparative Example 1 before stress-relief annealing are significantly different. The non-oriented electrical steel sheet of Example 1 has fully recrystallized before stress-relief annealing, while the comparative steel sheet of Comparative Example 1 has not fully recrystallized before stress-relief annealing. The average grain size of the non-oriented electrical steel sheet of Example 1 after stress-relief annealing is 160 μm, while the average grain size of the comparative steel sheet of Comparative Example 1 after stress-relief annealing is 100 μm.
[0105] Figure 3 shows the inclusion morphology of the non-oriented electrical steel sheet of Example 3.
[0106] Figure 4 shows the inclusion morphology of the comparative steel plate of Comparative Example 3.
[0107] As shown in Figures 3 and 4, the cleanliness of the non-oriented electrical steel sheet of Example 3 is significantly higher than that of the control steel sheet of Comparative Example 3. The non-oriented electrical steel sheet of Example 3 contains almost no fine sulfides or oxysulfides. In contrast, the control steel sheet of Comparative Example 3 contains more fine inclusions, and their size and morphology are irregularly distributed. These fine inclusions inhibit grain growth, which is detrimental to reducing iron loss on black sheets, thus affecting the magnetic properties of the finished steel sheet.
[0108] Samples of the non-oriented electrical steel sheets from Examples 1-8 and the comparative steel sheets from Comparative Examples 1-3 were taken before and after stress-relief annealing, and mechanical and electromagnetic properties were tested. The test results of each example and comparative example before and after stress-relief annealing are summarized in Table 4.
[0109] Electromagnetic performance testing: Iron loss and magnetic induction properties were determined using the Epstein square ring method according to national standard GB / T 3655-2008. The test temperature was a constant 20℃, the sample size was 30mm × 300mm, the sample mass was 0.5kg, and the test parameter was B. 5000 and P 1.0 / 400 .
[0110] Mechanical property testing: Mechanical property testing was conducted using plate-shaped samples according to national standard GB / T 228.1-2010. The test temperature was a constant 20℃, the gauge length of the sample was 50mm, and the evaluation parameter was the yield strength Y. S .
[0111] Table 4 lists the performance test results of the non-oriented electrical steel sheets of Examples 1-8 and the comparative steel sheets of Comparative Examples 1-3 before and after stress-relief annealing.
[0112] Table 4.
[0113] As can be seen from Table 4 above, the thickness of the non-oriented electrical steel sheets in Examples 1-8 is between 0.15 and 0.35 mm, and the yield strength Y before stress-relief annealing is... S ≥500MPa, iron loss P after stress-relief annealing 1.0 / 400 ≤11.5W / kg, magnetic induction B 5000 ≥1.65T.
[0114] Therefore, by adopting the optimized chemical composition ratio and process system of this invention, the resistivity of steel plates can be effectively improved, the formation of harmful inclusions can be reduced, and the grain size before and after stress relief annealing can be reasonably matched, thereby improving magnetic induction and yield strength, while significantly reducing iron loss.
[0115] All publications, patent applications, patents, and other references mentioned in this disclosure are incorporated herein by reference in their entirety.
[0116] While this disclosure has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the disclosure in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of this disclosure to these descriptions. Various changes in form and detail can be made by those skilled in the art, including some simple deductions or substitutions, without departing from the spirit and scope of this disclosure.
Claims
1. A non-oriented electrical steel sheet, characterized in that, In addition to Fe and unavoidable impurities, the non-oriented electrical steel sheet also contains the following chemical elements in the following mass percentages: 0 < C ≤ 0.0040%, preferably C: 0.0007-0.0040%; Si: 2.0-3.6%; Mn: 0.05-2.00%, preferably Mn: 0.24-2.00%; P: 0.02-0.12%; 0 < Al ≤ 2.00%, preferably Al: 0.10-2.00%; 0 < Mg ≤ 0.0050%; Ni: 0.01-0.50%, preferably Ni: 0.10-0.50%; Cr: 0.01-0.50%, preferably Cr: 0.10-0.50%.
2. The non-oriented electrical steel sheet as described in claim 1, characterized in that, The mass percentage content of each chemical element in the non-oriented electrical steel sheet is as follows: 0 < C ≤ 0.0040%, preferably C: 0.0007-0.0040%; Si: 2.0-3.6%; Mn: 0.05-2.00%, preferably Mn: 0.24-2.00%; P: 0.02-0.12%; 0 < Al ≤ 2.00%, preferably Al: 0.10-2.00%; 0 < Mg ≤ 0.0050%; Ni: 0.01-0.50%, preferably Ni: 0.10-0.50%; Cr: 0.01-0.50%, preferably Cr: 0.10-0.50%; the balance is Fe and unavoidable impurities.
3. The non-oriented electrical steel sheet as described in claim 1 or 2, characterized in that, Unavoidable impurities include S, N, and Ti, with S ≤ 0.0030%, N ≤ 0.0030%, and Ti ≤ 0.0020%.
4. The non-oriented electrical steel sheet as described in any one of claims 1 to 3, characterized in that, The combined amount of Si and Al is 3.2% to 4.6%.
5. The non-oriented electrical steel sheet as described in any one of claims 1 to 4, characterized in that, The non-oriented electrical steel sheet also contains at least one of the following chemical elements in the following mass percentages: 0 < Ca ≤ 0.005%; 0 < REM ≤ 0.005%.
6. The non-oriented electrical steel sheet as described in any one of claims 1 to 5, characterized in that, The non-oriented electrical steel sheet also contains at least one of Sn and Sb, wherein Sn: 0–0.20%, Sb: 0–0.10%, and 0 < Sn + Sb ≤ 0.25%.
7. The non-oriented electrical steel sheet according to any one of claims 1 to 6, characterized in that, The non-oriented electrical steel sheet has a fully recrystallized structure after stress-relief annealing, and the ratio of the average grain size after stress-relief annealing to that before stress-relief annealing is 2.5 to 5.0; and / or the average grain size of the non-oriented electrical steel sheet before stress-relief annealing is 25-60 μm; and / or the average grain size of the non-oriented electrical steel sheet after stress-relief annealing is 100-175 μm.
8. The non-oriented electrical steel sheet as described in any one of claims 1 to 7, characterized in that, The number of inclusions with an average size between 300-800 nm in the steel sheet after stress-relief annealing is ≤4.8×10⁻⁶. 6 / mm 3 .
9. The non-oriented electrical steel sheet according to any one of claims 1 to 8, characterized in that, The amount of inclusions in the steel plate after stress-relief annealing must meet the following requirement: 3.3% ≤ oxide inclusions / (oxide inclusions + sulfide inclusions + nitride inclusions) ≤ 8.1%.
10. The non-oriented electrical steel sheet according to any one of claims 1 to 9, characterized in that, The thickness of the non-oriented electrical steel sheet is 0.15 to 0.35 mm.
11. The non-oriented electrical steel sheet according to any one of claims 1 to 10, characterized in that, The yield strength Y of the non-oriented electrical steel sheet before stress-relief annealing S ≥500MPa.
12. The non-oriented electrical steel sheet according to any one of claims 1 to 11, characterized in that, The iron loss P of the non-oriented electrical steel sheet after stress-relief annealing 1.0 / 400 ≤11.5W / kg, magnetic induction B 5000 ≥1.65T.
13. A method for manufacturing non-oriented electrical steel sheet according to any one of claims 1 to 12, characterized in that, Includes the following steps: (1) Smelting and casting; (2) Heating and hot rolling; (3) Normalizing and bell-type furnace annealing: The soaking temperature for normalizing and bell-type furnace annealing is 850-1000℃, and the soaking time is 60-300s; (4) Cold rolling; (5) Continuous annealing: The soaking temperature for continuous annealing is 700-1050℃ and the soaking time is 5-60s.
14. The method as described in claim 13, 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 500-800℃.
15. The method as described in claim 13 or 14, characterized in that, The method further includes step (6) stress-relief annealing, wherein the soaking temperature for stress-relief annealing is T. 均热 =T 再结晶开始温度 +(80~155℃).