High-strength and low-loss non-directional electrical steel sheet and method for manufacturing the same.

Abstract

In the present invention, a non-oriented electrical steel sheet is disclosed. In addition to Fe and inevitable impurities, the non-oriented electrical steel sheet further contains the following chemical elements in wt%: 0 < C ≤ 0.0035%, Si: 2.00 - 3.80%, Mn: 0.05 - 1.00%, Al: 0.10 - 1.20%, and Cu: 0.05 - 2.00%. Correspondingly, in the present invention, a method for manufacturing the non-oriented electrical steel sheet is further disclosed, wherein in a heating step, the heating rate of a casting slab in a temperature range of 940 - 1030°C is 4.5 - 8.4°C / min ; and in a flattening step, the flattening reduction rate is controlled to be 0.5 - 8.0%. By using this technical solution, the non-oriented electrical steel sheet has high strength and also has low iron loss performance.

Description

[Technical Field]

[0001] Technical field The present invention relates to steel sheets and methods for manufacturing the same, and more particularly to non-oriented electrical steel sheets and methods for manufacturing the same. [Background technology]

[0002] Background technology In recent years, in order to continuously improve the power efficiency of components such as high-speed power tools and drive motors for new energy vehicles, non-oriented electrical steel sheets, which are the main raw materials for these components, are expected to have a finished thickness of 0.30 mm or less, significantly reducing the iron loss of the steel sheets. Furthermore, as the demand for lightweight core designs increases, it is expected that the yield strength of the finished steel sheets will need to be 500 MPa or higher.

[0003] For example, publication number CN107974620A, publication date May 1, 2018, and the title of the invention, "Non-oriented silicon steel having a yield strength of ≥600 MPa for high-speed motors and a method for manufacturing the same," discloses non-oriented silicon steel for high-speed motors with a yield strength of 600 MPa and a method for manufacturing the same. The chemical composition of this silicon steel is C: 0.001%~0.003%, Si: 2.6%~3.4%, Mn: 0.20%~0.60%, P≦0.005%, S≦0.005%, Al: 0.75%~0.95%, N: 0.002%~0.006%, Nb: 0.053%~0.20%, and the remainder These are Fe and unavoidable impurities. Furthermore, the relationship 4.5% ≤ Si + 2Als - 0.5Mn + 2.92P ≤ 5.0% is satisfied. It must be added that the soluble niobium content is 0.04% ≤ Nb% ≤ 0.08%, and Nb% = (Nb / 93 - C / 12 - N / 14) * 100, 1 ≤ N / C ≤ 3. The manufacturing process for non-oriented silicon steel is as follows: The process involves: smelting in a converter and casting into continuous billets; heating the continuous billets, performing conventional rough and finish rolling, and controlling the thickness of the hot-rolled sheet to 2.10 ± 0.05 mm; and firing. During the normalizing process, the normalizing temperature is controlled to be between 840 and 940°C; normalized steel The coil is pickled and then cold-rolled, and the cold-rolled finished product has a thickness of 0.35 mm or less. Next, the cold-rolled finished products are continuously annealed, with the soaking temperature controlled to 780-820°C, the soaking time to 60-120 seconds, and the atmosphere to pure dry N2. The resulting steel sheets, having a finished thickness of 0.35 mm or less, achieve the following mechanical properties: yield strength ≥600MPa, tensile strength ≥700MPa, iron loss P 10 / 400 ≤35 W / kg, and magnetic induction B 50 ≥1.60T. This Technical solutions primarily rely on the Nb element, but the iron loss in non-oriented electrical steel sheets remains insufficiently low. [Overview of the Initiative] [Means for solving the problem]

[0004] Abstract One objective of the present invention is to provide high-strength, low-iron-loss, non-oriented electrical steel sheets. By employing a novel chemical composition design and a suitable process, the present invention provides white sheets (continuous). Ensure that the steel for (after further annealing and proper planarization) has high strength, and that the steel for black plates (after stress-relieving annealing) has low iron loss.

[0005] To achieve the above objective, the present invention provides a non-oriented electrical steel sheet. In addition to Fe and unavoidable impurities, the steel sheet further contains the following chemical elements in wt%: 0 <C≦0.0035%、Si:2.00~3.80%、Mn:0.05~1.00%、Al:0.10~1.20%、およびCu:0.05~2.00%。

[0006] Preferably, the present invention provides a non-oriented electrical steel sheet containing the following chemical elements in wt%: 0 < C ≤ 0.0035%, Si: 2.00 - 3.80%, Mn: 0.05 - 1.00%, Al: 0.10 - 1.20%, Cu: 0.05 - 2. 00%, and the balance is Fe and unavoidable impurities.

[0007] In the non - oriented electrical steel sheet of the present invention, the design principle of chemical elements is as follows: C: When the content of C exceeds 0.0035%, it easily combines with harmful elements in the steel to generate a large number of harmful inclusions, which fix particle growth during the continuous annealing process and stress - relieving annealing process, thereby abnormally increasing the iron loss of the finished steel sheet. Based on this, the mass percentage of C is 0 < C ≤ 0.0035%, for example, 0.0014% ≤ C ≤ 0.0029%.

[0008] Si: Si affects both the electromagnetic properties and mechanical properties of the finished steel sheet. In the present invention, when the content of Si exceeds 3.80%, the magnetic induction of the finished steel sheet is significantly deteriorated, and its cold rolling workability is reduced; when the content of Si is less than 2.00%, the core loss cannot be effectively reduced and the mechanical strength cannot be improved. Based on this, the mass percentage of Si is 2.00% - 3.80%. For example, the lower limit of the content of Si can be 2.08%, and the upper limit can be 3.78%, 3.45%.

[0009] Mn: Mn combines with the impurity element S to form MnS, which is beneficial for controlling the form and amount of inclusions, thereby effectively reducing their adverse effects on magnetic properties. Therefore, in the present invention, it is necessary to add Mn of 0.05% or more. When the content of Mn exceeds 1.00%, it easily destroys the recrystallization beneficial structure of the finished steel sheet and can greatly increase the manufacturing cost of the steel. Based on this, the mass percentage of Mn is 0.05% - 1.00%. For example, the lower limit of the content of Mn can be 0.19%, 0.25%, and the upper limit can be 0.83%.

[0010] Al: Al can significantly increase the electrical resistivity of the material and improve the iron loss performance of the finished steel sheet. In the present invention, when the content of Al is less than 0.10%, it is impossible to effectively reduce the iron loss; when the content of Al exceeds 1.20%, the malleability of continuously casting molten steel significantly deteriorates. Based on this, the mass percentage of Al is 0.10% - 1.20%. For example, the lower limit of the Al content can be 0.40%, and the upper limit can be 1.16%.

[0011] Cu: In the present invention, reasonable design of the Cu content is very important. For non-oriented electrical steel with a high Si + Al content, harmful inclusions are fine and numerous sulfur-based inclusions, which strongly inhibit particle growth during continuous annealing, especially stress relief annealing, thereby directly causing a significant decrease in the iron loss of the finished steel sheet. Furthermore, under the same S content, the thinner the finished steel sheet, the greater its adverse effect on iron loss. To better control sulfide inclusions, the present invention adds 0.05% or more of Cu to the steel to form spherical Cu S x inclusions, thereby reducing their harm. However, when the content of Cu exceeds 2.00%, it reduces the recrystallization effect during hot rolling, and the content of beneficial structures may be reduced, thereby significantly reducing the magnetic induction of the steel sheet. Based on this, the mass percentage of Cu is 0.05% - 2.00%. To further improve the beneficial effects of the steel sheet, the mass percentage of Cu is preferably controlled at 0.10% - 1.20%.

[0012] Preferably, the non-oriented electrical steel sheet of the present invention further contains at least one of Sn and Sb in a total amount of 0.005 - 0.200% by wt%. Sn and Sb are abundant on the surface and segregate at grain boundaries. These are elements that can inhibit surface nitriding and oxidation of the finished steel sheet during heat treatment. Therefore, preferably, the present invention allows the addition of 0.005% or more of Sn and Sb in total. However, if the total content of Sn and Sb exceeds 0.200%, it causes severe particle refinement in the finished product and deteriorates the electromagnetic properties of the finished steel sheet. More preferably, the mass percentage of Sn + Sb The percentage is between 0.010% and 0.150%.

[0013] The respective contents of Sn and Sb are, in particular, as long as the total amount of Sn + Sb satisfies the above limitations. It is not limited. For example, the Sn content can be 0-0.100% (e.g., 0.002-0.009%), and The Sb content can range from 0 to 0.130% (for example, 0.003 to 0.100%).

[0014] Preferably, the non-oriented electrical steel sheet of the present invention further comprises at least one of Ca, Mg, and REM in a total amount of 0.0003 to 0.0035% by wt%. Ca, Mg, and REM provide strong deoxidation and desulfurization. These have the ability to form large particulate inclusions that promote their suspension and removal, and they can also inhibit the precipitation of fine sulfides, which is very beneficial in improving the cleanliness of steel. Therefore, preferably, the present invention allows the addition of at least one of Ca, Mg, and REM in an amount of 0.0003% or more. However, if the total content of Ca, Mg, and REM is 0.0035%, If this value is exceeded, it greatly increases the manufacturing cost of the steel and also does not contribute to the stability of continuous casting. More preferably, the mass percentage of Ca+Mg+REM is 0.0005 to 0.0025%.

[0015] The respective contents of Ca, Mg, and REM are not particularly limited, as long as the total amount of Ca + Mg + REM satisfies the above limitations. For example, the Ca content is 0 to 0.0021% (e.g., 0.0007 to 0.0021%). The Mg content may be 0-0.0010% (e.g., 0.0003-0.0010%), and the REM content may be 0-0.0014% (e.g., 0.0007-0.0014%).

[0016] Preferably, the unavoidable impurities include P, S, and N, and their content is as follows: At least one of the following conditions is satisfied: P ≤ 0.20%, S ≤ 0.0030%, N ≤ 0.0020%.

[0017] The main impurity elements in this invention are S, P, and N, and their content is It should be controlled to the lowest possible level. Among them: In this invention, if the P content exceeds 0.20%, the cold-rolling workability of the high-silicon and high-aluminum-silicon steel decreases significantly, causing abnormalities such as edge cracking or strip breakage. Preferably, P ≤ 0.19% (for example, 0.01 to 0.19%).

[0018] If the S content exceeds 0.0030%, there is a significant increase in the number of inclusions such as MnS and Cu2S in the steel. This easily induces particle growth, which strongly inhibits particle growth during continuous annealing processes, especially stress relief annealing processes, and degrades the electromagnetic properties of the finished steel sheet. Preferably, S ≤ 0.0028% (e.g., 0.0007~0.0028%).

[0019] If the N content exceeds 0.0020%, the inclusions increase significantly, which strongly inhibits particle growth in the finished steel sheet and degrades the electromagnetic properties of the finished steel sheet. For example, 0.0010% ≤N ≤ 0.0020%.

[0020] Preferably, the mass percentage of element Cu is more preferably 0.10-1.20%.

[0021] Preferably, the thickness of the non-oriented electrical steel sheet of the present invention is ≤0.30 mm.

[0022] More preferably, the thickness of the non-oriented electrical steel sheet of the present invention is ≤0.27 mm.

[0023] Preferably, the non-oriented electrical steel sheet of the present invention (for example, obtained after continuous annealing and planarization) The steel used for the white plates has a yield strength of ≥500 MPa and a tensile strength of ≥600 MPa.

[0024] Preferably, the non-oriented electrical steel sheet of the present invention (for example, stress relief annealing as needed) The steel used for the black plates obtained later has an iron loss P of ≤12.0 W / kg. 10 / 400 and magnetic induction B ≥ 1.62 T 50 It has.

[0025] Another object of the present invention is to optimize the heating rate of the cast slab in the hot rolling furnace by a specific composition design, and to use appropriate planar reduction to reduce the thickness of the steel sheet, thereby resulting in a white steel sheet with high strength obtained after continuous annealing and appropriate planarization, and The objective is to provide a method for producing non-oriented electrical steel sheets for black plates that have low iron loss after stress relief annealing.

[0026] To achieve the above objectives, the present invention provides a method for manufacturing non-oriented electrical steel sheets, comprising the following steps: (1) Smelting and casting to obtain a cast slab; (2) Hot rolling including heating, rough rolling, finish rolling, and coil winding, where heating step In this case, the heating rate of the cast slab in the 940-1030°C range is 4.5-8.4°C / min; (3) Normalizing and annealing; (4) Cold rolling; (5) Continuous annealing; and (6) The plate is flattened and an insulating coating is applied to obtain a white steel plate, where the flattening reduction ratio The concentration is 0.5 to 8.0%, preferably 1.0 to 5.0%.

[0027] Preferably or as needed, the method further includes: (7) The white steel sheet obtained in step (6) is subjected to stress relief annealing to obtain a black steel sheet.

[0028] For example, in process (1), smelting and casting are: molten iron in a blast furnace → molten iron pretreatment → converter This process may include smelting, RH smelting, and continuous casting.

[0029] For example, in process (2), hot rolling is: reheating of the continuous cast slab → rough rolling → finishing. Rolling may include coil winding.

[0030] For example, in process (3), normalizing annealing is: preheating of the heat coil → soaking → cooling. This can include shot blast.

[0031] For example, in process (4), cold rolling is: normalizing coil pickling → cold rolling → coil It may include winding.

[0032] For example, in process (5), continuous annealing is performed as follows: cold coil pre-cleaning → continuous annealing → May include post-cleaning.

[0033] For example, the manufacturing process may employ single cold rolling + continuous annealing, or further employ primary cold rolling + intermediate annealing + secondary cold rolling + continuous annealing to obtain better electromagnetic properties of the finished steel sheet.

[0034] In step (6), a white steel sheet is obtained after planarization and application of an insulating coating.

[0035] In step (7), a black steel sheet is obtained after stress relief annealing (if necessary, for example, to further reduce iron loss).

[0036] In step (2) of the method of the present invention, in the heating step, the heating rate of the casting slab (for example, a continuous casting slab) in the range of 940 to 1030 °C is controlled to be 4.5 to 8.4 °C / min. The reason is that in this temperature range, a large amount of Cu x S dissolves, and then in the rolling process, when the temperature decreases, secondary precipitation occurs, the number of inclusions increases sharply, and the particle size decreases significantly, causing greater harm. At this point, adopting a rapid heating rate of 4.5 to 8.4 °C / min can effectively avoid the harmful effects such as excessive dissolution of Cu x S and formation of unfavorable structures. Conversely, when the heating rate exceeds 8.4 °C / min, it causes a large difference in the temperature gradient along the thickness direction of the casting slab, which does not contribute to the formation of a coarse and well-developed recrystallized microstructure. Another important process of the present invention is an appropriate flattening reduction rate. Here, the flattening reduction rate is 0.5 to 8.0%, more preferably 1.0 to 5.0%. When the flattening reduction rate is less than 0.5%, it has almost no effect on improving the strength of the steel plate. When the flattening reduction rate exceeds 8.0%, it causes a sharp increase in the stored energy of the steel plate, severely deteriorates the favorable structure of the steel plate, and as a result, causes a significant decrease in the iron loss and the magnetic induction improvement effect of the steel plate after stress relief annealing, failing to meet the performance requirements of iron loss P ≦12.0 W / kg and magnetic induction B

[0037] ≧1.62 T. 10 / 400 In some embodiments of the present invention, the thickness of the steel plate after hot rolling is 1.2 to 3.0 mm, preferably 1.2 to 2.0 mm. The annealed steel coil can be rolled to the target steel plate thickness in a single rolling step in the subsequent cold rolling process. 50 Preferably, in the heating step of step (2), the heating time of the casting slab in the furnace is 120 to 360 minutes.

[0038]

[0039] ​​​The exhaust temperature is 1050-1150°C.

[0040] Preferably, in step (2), the rough rolling start temperature is 1030-1130°C; and / or the finish rolling end temperature is 650-950°C; and / or the coil winding temperature is 500-850°C. be.

[0041] Preferably, the thickness of the steel sheet obtained in step (2) is 1.2 to 3.0 mm, and more preferably 1.2 to 2.0 mm.

[0042] Preferably, in step (3), the soaking temperature for normalizing and annealing is 820 to 980°C. The soaking time is 1 to 10 minutes.

[0043] In the composition design of the present invention, the soaking temperature of the hot-rolled steel coil during normalizing and annealing can be appropriately raised to 820-980°C, and the normalizing and annealing soaking time can be extended to 1-10 minutes. By lengthening the particle structure and achieving a coarser and more developed particle structure, it is possible to improve the magnetic induction of the steel sheet and reduce its iron loss.

[0044] Preferably, in step (4), single cold rolling is employed, or intermediate annealing is performed. A two-stage cold rolling process is employed, where the soaking temperature for the intermediate annealing is 720-950°C and the soaking time is 10-60 seconds.

[0045] Preferably, in step (5), the soaking temperature for continuous annealing is 720 to 950°C, and The soaking time is 10 to 60 seconds.

[0046] For example, a continuous annealing atmosphere is a mixture of hydrogen and nitrogen gases (dry atmosphere) with a hydrogen content of 10–45% by volume.

[0047] Preferably, the iron loss P of the white steel sheet obtained in step (6) 10 / 400 It is ≤ 19.2 W / kg; More preferably, the white steel sheet has a yield strength of ≥500 MPa, a tensile strength of ≥600 MPa, and a magnetic induction strength of ≥1.62 T. 50 It has.

[0048] Preferably, the iron loss P of the black steel sheet obtained in step (7) 10 / 400 It is ≤ 12.0 W / kg; More preferably, the black steel sheet has a yield strength of ≥500 MPa, a tensile strength of ≥600 MPa, and ≥1.62 Magnetic induction B 50 It has.

[0049] The non-oriented electrical steel sheet of the present invention has the beneficial effects of both high strength and excellent magnetic properties. Specifically, the white steel sheet obtained after continuous annealing and planarization is subjected to a pressure of ≥500 MPa. Tension strength, tensile strength of ≥600 MPa (preferably magnetic induction B of ≥1.62 T) 50 and iron loss P ≤ 19.2 W / kg 10 / 400 The black steel sheet obtained after stress relief annealing has an iron content of ≤12.0 W / kg. Loss P 10 / 400 and magnetic induction B ≥ 1.62 T 50 (Preferably having a yield strength of ≥500 MPa and a tensile strength of ≥600 MPa). [Brief explanation of the drawing]

[0050] [Figure 1] Figure 1 shows the relationship between the wt% of element Cu in the non-oriented electrical steel sheet of the present invention and the iron loss P10 / 400 after stress relief annealing. [Figure 2] Figure 2 shows the relationship between the planarization reduction ratio and yield strength of the non-oriented electrical steel sheet of the present invention. [Figure 3] Figure 3 shows the relationship between the planarization reduction ratio and tensile strength of the non-oriented electrical steel sheet of the present invention.

[0051] Detailed explanation The non-oriented electrical steel sheet and its manufacturing method according to the present invention will be further described below with reference to specific embodiments and accompanying drawings. However, the description and representation will not constitute an inappropriate limitation to the technical solution of the present invention.

[0052] As described above, the inventors have found that under the composition system of the present invention, the mass percentage of element Cu in the non-oriented electrical steel sheet is the iron loss P of the steel sheet after stress relief annealing. 10 / 400 It is closely related to It was discovered through investigation.

[0053] Figure 1 shows the mass percentage of element Cu in the non-oriented electrical steel sheet of the present invention and the iron loss P after stress relief annealing. 10 / 400 This shows the relationship between the two. As shown in Figure 1, when the mass percentage of element Cu is 0.5%, the iron loss P 10 / 400 The iron loss P decreases to 12.0 W / kg, and when the mass percentage of element Cu is 1.6-1.8%, 10 / 400 It reaches its minimum value. However, if the element Cu content exceeds 2.00%, iron loss P 10 / 400 It increases again to over 12.0 W / kg. Therefore, the mass percentage of element Cu is set to 0.05 to 2.00% in this invention.

[0054] Furthermore, the inventors have also found through investigation that the planarization reduction ratio of non-oriented electrical steel sheets having the composition ratio of the present invention is closely related to their yield strength and tensile strength.

[0055] Figure 2 shows the relationship between the planarization reduction ratio and yield strength of the non-oriented electrical steel sheet of the present invention.

[0056] As shown in Figure 2, when the flattening reduction ratio of the steel plate is 0.5%, the yield strength of the steel plate is 500 MPa. It reaches this point. Subsequently, as the flattening reduction ratio increases, the yield strength of the steel plate continues to increase.

[0057] Figure 3 shows the relationship between the planarization reduction ratio and tensile strength of the non-oriented electrical steel sheet of the present invention.

[0058] As shown in Figure 3, when the flattening reduction ratio of the steel plate is 0.5%, the tensile strength of the steel plate is 600 MPa. The above is reached. Subsequently, as the flattening reduction ratio increases, the tensile strength of the steel plate continues to increase.

[0059] Examples 1-6 and Comparative Examples 1-2 Tables 1-1 and 1-2 list the chemical composition (in wt%) of the non-oriented electrical steel sheets of Examples 1-6 and Comparative Examples 1-2, where the remainder consists of Fe and unavoidable impurities other than S, P, and N.

[0060] [Table 1-1]

[0061] [Table 1-2]

[0062] The non-oriented electrical steel sheets of Examples 1-6 and Comparative Examples 1-2 were prepared by the following process ( See Table 2 for specific process parameters. The crucial difference is that the process parameters for Comparative Examples 1 and 2 do not satisfy one or more of the following parameters: (1) Smelting and casting to produce cast slabs: Molten iron from the blast furnace is pre-treated It underwent "three removals" in the furnace, then mixed with the appropriate proportion of scrap iron, and was subsequently fed into the furnace. It then underwent smelting in an upper and lower blown converter, RH smelting, and continuous casting, producing 170-250 A cast slab with a thickness of mm and a width of 800 to 1400 mm was obtained.

[0063] (2) Hot rolling including heating, rough rolling, finish rolling, and coil winding: In the heating process The heating time of the cast slabs in the furnace was 120-360 minutes, the discharge temperature was 1050-1150°C, and the heating rate of the cast slabs in the temperature range of 940-1030°C was 4.5-8.4°C / min; rough rolling The starting temperature was 1030-1130°C, the finish rolling end temperature was 650-950°C, and the coil winding temperature was 500-850°C.

[0064] (3) Normalizing annealing: The soaking temperature for normalizing annealing is 820-980°C, The soaking time was 1 to 10 minutes.

[0065] (4) Cold rolling and continuous annealing: For Examples 1, 2, 4, and 5 and Comparative Example 1, single cold rolling was performed to the final product thickness, followed by continuous annealing; for Examples 3, 6, and Comparative Example 2, primary cold rolling + intermediate annealing + secondary cold rolling + continuous annealing The following process was adopted; here, the continuous annealing soaking temperature was 720~950°C, the soaking time was 10~60 seconds, and the continuous annealing atmosphere was a mixture of hydrogen and nitrogen (dry atmosphere). The gaseous state had a hydrogen content of 10-45% by volume. In the case of intermediate annealing, the process parameters for intermediate annealing were the same as those for continuous annealing.

[0066] (5) The plate is flattened and an insulating coating is applied to obtain a white steel plate, where the flattening reduction ratio The percentage ranged from 0.5% to 8.0%.

[0067] (6) Stress relief annealing was performed to obtain black steel plates.

[0068] Tables 2-1 and 2-2 describe the specific process parameters for the manufacturing methods of non-oriented electrical steel sheets in Examples 1-6 and Comparative Examples 1-2.

[0069] [Table 2-1]

[0070] [Table 2-2]

[0071] The inventors took samples of non-oriented electrical steel sheets from Examples 1-6 and Comparative Examples 1-2, observed these samples, and tested their relevant properties. The relevant performance results are shown in Table 3. The relevant test methods are as follows: Iron loss: Tested using the Epstein frame method in accordance with national standard GB / T 3658-1990. The test temperature was 20°C (constant temperature), and the sample size was 30 mm × 300 mm. The mass is 0.5 kg, and the test parameter is P 10 / 400 That was the case.

[0072] Magnetic induction: Tested using the Epstein frame method in accordance with national standard GB / T 3658-1990. The test temperature was 20°C (constant temperature), and the sample size was 30 mm × 300 mm. The target mass is 0.5 kg, and the test parameter is B 50 That was the case.

[0073] Mechanical properties: Tested according to national standard GB / T 228.1-2010, Metallic materials - Tensile testing - Part 1: Test method at room temperature. Standard test samples were used after machining. The test temperature was room temperature, and the gauge length of the test sample was 50 mm.

[0074] [Table 3]

[0075] Examples 1 to 6 satisfy the design requirements of the present invention, and the corresponding chemical composition design and casting slab By adopting the control requirements for heating rate and planar reduction ratio, all white steel sheets after continuous annealing and planarization have a yield strength exceeding 500 MPa, a tensile strength exceeding 600 MPa, and 20.0 Iron loss less than W / kg P 10 / 400 , and magnetic induction B exceeding 1.62 T 50 It can be seen that this indicates... Furthermore, after stress relief annealing, all black steel plates have a further reduced iron loss P of less than 12.0 W / kg. 10 / 400 It achieved a magnetic induction B exceeding 1.62 T, while on the other hand, it exceeded 1.62 T. 50 It maintains a yield strength exceeding 500 MPa and a tensile strength exceeding 600 MPa.

[0076] In Comparative Example 1, this method did not meet the design requirements of the present invention, and heating of the cast slab The rate was only 3.2°C / min, which is below the lower limit of 4.5°C / min specified by the present invention, and planarization was not performed after continuous annealing. Therefore, the white in Comparative Example 1 The yield strength of the colored steel sheet was 483 MPa, and the tensile strength was 551 MPa, both of which are lower than the lower limits of 500 MPa and 600 MPa, respectively, specified by the present invention. Furthermore, the iron loss of the black steel sheet in Comparative Example 1 was 12.3 W / kg (higher than the upper limit of 12.0 W / kg specified by this application), and the magnetic induction was 1.60 T (lower than the lower limit of 1.62 T specified by this application).

[0077] In Comparative Example 2, this method does not conform to the design requirements of the present invention. The Cu content is only 0.01%, which is lower than the 0.05% lower limit of the design requirements of the present invention. Furthermore, the Si content is high at 3.91%, exceeding the 3.8% upper limit of the design requirements of the present invention. Consequently, after continuous annealing and planarization, the yield strength of the white steel sheet is 518 MPa and the tensile strength is 603 MPa, which satisfy the lower limits of 500 MPa and 600 MPa of the design requirements of the present invention. However, after stress relief annealing, the iron loss P of the black steel sheet is lower. 10 / 400It is 14.4 W / kg, and magnetic induction B 50 It is 1.61 T, This is the iron loss P identified by the present invention. 10 / 400 ≤ 12.0 W / kg and magnetic induction B 50 It does not satisfy the requirement of ≥ 1.62T.

[0078] It should be noted that the combination of technical features in this invention is not limited to the combination of specific embodiments of the invention described in the claims. All technical features described herein can be freely combined or integrated in any way, as long as they do not conflict with each other.

[0079] Furthermore, it should be noted that the embodiments described above are merely specific implementations of the present invention. Needless to say, the present invention is not limited to these embodiments. Similar variations or modifications that can be directly derived from or readily conceived by those skilled in the art from the disclosure of the present invention are within the scope of protection of the present invention.

Claims

1. In addition to Fe and unavoidable impurities, the following chemical elements are further present in wt% form: non-directional electromagnetic Steel plate: 0 < C ≤ 0.0035%, Si: 2.00–3.80%, Mn: 0.05–1.00%, Al: 0.10–1.20%, and Cu: 0.05–2.00%.

2. The non-oriented electrical steel sheet according to claim 1, comprising the following chemical elements in wt%: 0 < C ≤ 0.0035%, Si: 2.00–3.80%, Mn: 0.05–1.00%, Al: 0.10–1.20%, Cu: 0.05–2.00%, with the remainder being Fe and unavoidable impurities.

3. Claim 1 or 2 further comprises, in wt% form, at least one of Sn and Sb in a total amount of 0.005 to 0.200%, and / or at least one of Ca, Mg, and REM in a total amount of 0.0003 to 0.0035%. Non-oriented electrical steel sheet as described above.

4. The unavoidable impurities include at least one of P, S, and N, and their content satisfies at least one of the following: P ≤ 0.20%, S ≤ 0.0030%, N ≤ 0.0020%, as described in claim 1 or 2. Non-oriented electrical steel sheet.

5. The non-oriented electrical steel sheet according to claim 1 or 2, wherein the content of element Cu is 0.10 to 1.20%.

6. The non-oriented electromagnetic steel sheet according to claim 1 or 2, wherein the thickness of the non-oriented electromagnetic steel sheet is ≤0.30 mm. steel plate.

7. A non-oriented electrical steel sheet according to claim 1 or 2, having a yield strength of ≥500 MPa and a tensile strength of ≥600 MPa.

8. Iron loss P ≤ 12.0 W / kg 10 / 400 and magnetic induction B ≥ 1.62 T 50 Claim 1 or 2, having Non-oriented electrical steel sheet as described above.

9. A method for manufacturing a non-oriented electrical steel sheet according to any one of claims 1 to 8, comprising the following steps: (1) Smelting and casting to obtain a cast slab; (2) Hot rolling including heating, rough rolling, finish rolling, and coil winding; where the heating step In this case, the heating rate of the cast slab in the temperature range of 940–1030°C is 4.5–8.4°C / min; (3) Normalizing and annealing; (4) Cold rolling; (5) Continuous annealing; and (6) The steel is flattened and an insulating coating is applied to obtain a white steel sheet, where the flattening reduction ratio is 0.5 to 8.0%, preferably 1.0 to 5.0%.

10. (7) The method according to claim 9, further comprising subjecting the white steel sheet obtained in step (6) to stress relief annealing to obtain a black steel sheet.

11. The method according to claim 9 or 10, wherein step (2) satisfies one or more of the following: In the heating process, the furnace heating time for the casting slab is 120 to 360 minutes, and the discharge temperature is 1050 to 1150°C; The starting temperature for rough rolling is 1030–1130°C; The finishing rolling temperature is 650 to 950°C; The coil winding temperature is 500-850°C; and The thickness of the steel plate obtained in step (2) is 1.2 to 3.0 mm, preferably 1.2 to 2.0 mm.

12. In step (3), the soaking temperature for normalizing and annealing is 820 to 980°C, and soaking The method according to claim 9 or 10, wherein the time is 1 to 10 minutes.

13. In process (4), single cold rolling is employed, or a two-stage cold rolling process with intermediate annealing is performed. The method according to claim 9 or 10, wherein intermediate rolling is employed, the soaking temperature for intermediate annealing is 720 to 950°C, and the soaking time is 10 to 60 seconds.

14. The method according to claim 9 or 10, wherein in step (5), the soaking temperature for continuous annealing is 720 to 950°C and the soaking time is 10 to 60 seconds; and / or the continuous annealing atmosphere is a hydrogen-nitrogen mixed gas, wherein the hydrogen content is 10 to 45% by volume.

15. Iron loss P of the white steel sheet obtained in process (6) 10 / 400 The ratio is ≤ 19.2 W / kg; preferably, white steel The plate has a yield strength of ≥500 MPa, a tensile strength of ≥600 MPa, and a magnetic induction B of ≥1.62 T. 50 possess The method according to claim 9.

16. Iron loss P of the black steel plate obtained in process (7) 10 / 400 The ratio is ≤ 12.0 W / kg; preferably, black steel The plate has a yield strength of ≥500 MPa, a tensile strength of ≥600 MPa, and a magnetic induction B of ≥1.62 T. 50 possess The method according to claim 10.

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