Non-oriented electromagnetic steel sheet and method for manufacturing the same

Abstract

The chemical composition of the base material of this non-oriented electromagnetic steel sheet, in mass percent, is as follows: C: 0–0.0050%, Si: 3.8–4.9%, Mn: 0.05–1.20%, SO2·Al: more than 0.02% and less than 0.50%, P: 0–0.030%, S: 0–0.0030%, N: 0–0.0030%, Ti: more than 0% and less than 0.0050%, Nb: more than 0%. Less than 0.0050%, Zr: 0% or more, less than 0.0050%, V: 0% or more, less than 0.0050%, Cu: 0% or more, less than 0.200%, Ni: 0% or more, less than 0.500%, Sn: 0-0.100%, Sb: 0-0.100%, and the remainder: Fe and impurities, satisfying [4.3≤Si+sol.Al+0.5×Mn≤5.0], [B 50 (0°)-B 50 (45°)≤0.16] and [(B 50 (0°)+2×B 50 (45°)+B 50 (90°)) / 4≥1.57], tensile strength is above 580MPa.

Description

Technical Field

[0001] This invention relates to a non-oriented electromagnetic steel sheet and its manufacturing method.

[0002] This application claims priority based on Japanese Patent Application No. 2021-023510 filed on February 17, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] In recent years, global environmental issues have garnered significant attention, leading to increased demands for energy conservation. Within these energy conservation efforts, there is a strong need for higher efficiency in electrical equipment. Consequently, the requirements for improving the magnetic properties of non-oriented electromagnetic steel sheets, widely used as core materials for motors and generators, have intensified. This trend is particularly pronounced in drive motors for electric and hybrid vehicles, as well as in compressor motors for air conditioners.

[0004] As described above, the motor core of various motors consists of a stator as the stationary element and a rotor as the rotating element. The required characteristics of the stator and rotor constituting the motor core are different from each other. For the stator, excellent magnetic properties (low iron loss and high magnetic flux density) are required, especially low iron loss. For the rotor, excellent mechanical properties (high strength) are required.

[0005] Because the required properties differ between the stator and rotor, the desired characteristics can be achieved by manufacturing separate non-oriented electromagnetic steel sheets for the stator and rotor. However, preparing two types of non-oriented electromagnetic steel sheets leads to a decrease in yield. Therefore, in order to achieve the high strength required for the rotor and the low iron loss required for the stator even without strain-reducing annealing, research has been ongoing on a non-oriented electromagnetic steel sheet with excellent strength and magnetic properties.

[0006] For example, in Patent Documents 1 and 2, attempts were made to achieve high strength and excellent magnetic properties.

[0007] Prior technology documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 2019 / 017426

[0010] Patent Document 2: International Publication No. 2020 / 091039

[0011] Patent Document 3: Japanese Patent Application Publication No. 2013-91837

[0012] Patent Document 4: Japanese Patent Application Publication No. 2002-14691

[0013] Patent Document 5: Japanese Patent Application Publication No. 2001-295003 Summary of the Invention

[0014] The technical problem that the invention aims to solve

[0015] However, in order to achieve a non-oriented electromagnetic steel sheet that balances high strength and low iron loss, as disclosed in Patent Documents 1 and 2, it is necessary to contain a large amount of alloying elements. This results in a decrease in toughness, making it more susceptible to fracture during cold rolling. Furthermore, in Patent Document 1, to ensure sufficiently low iron loss for the stator, further strain-de-strain annealing is required.

[0016] This invention was made to solve such problems, and its purpose is to stably provide a non-oriented electromagnetic steel sheet with high strength and excellent magnetic properties.

[0017] Technical means for solving technical problems

[0018] The present invention focuses on the following non-oriented electromagnetic steel sheet and its manufacturing method.

[0019] (1) Regarding a non-oriented electromagnetic steel sheet according to one embodiment of the present invention,

[0020] The chemical composition of the base material, expressed as a percentage by mass, is:

[0021] C: 0~0.0050%

[0022] Si: 3.8-4.9%

[0023] Mn: 0.05~1.20%

[0024] sol.Al: Above 0.02%, below 0.50%,

[0025] P: 0–0.030%

[0026] S: 0~0.0030%

[0027] N: 0~0.0030%

[0028] Ti: 0% or more, less than 0.0050%

[0029] Nb: 0% or more, less than 0.0050%

[0030] Zr: 0% or more, less than 0.0050%

[0031] V: Above 0%, less than 0.0050%

[0032] Cu: 0% or more, less than 0.200%

[0033] Ni: 0% or more, less than 0.500%

[0034] Sn: 0~0.100%

[0035] Sb: 0–0.100%, and

[0036] Remaining components: Fe and impurities;

[0037] It satisfies the following equations (i) to (iii);

[0038] The tensile strength is above 580 MPa.

[0039] 4.3≤Si+sol.Al+0.5×Mn≤5.0···(i)

[0040] In equation (i) above, the element symbols represent the content (mass%) of each element.

[0041] B 50 (0°)-B 50 (45°)≤0.16···(ii)

[0042] (B 50 (0°)+2×B 50 (45°)+B 50 (90°)) / 4≥1.57···(iii)

[0043] Among them, B in equations (ii) and (iii) above 50 (0°) represents the magnetic flux density (T) under a magnetizing force of 5000 A / m in the rolling direction, B 50 (45°) represents the magnetic flux density (T) at a magnetization force of 5000 A / m at a 45° angle from the rolling direction, B 50 (90°) is the magnetic flux density (T) at a magnetizing force of 5000 A / m at a direction 90° away from the rolling direction.

[0044] (2) Alternatively, regarding the non-oriented electromagnetic steel sheet as described in (1) above, the chemical composition, in mass percent, contains from

[0045] Sn: 0.005–0.100%, and

[0046] Sb: 0.005~0.100%

[0047] Choose one or two from them.

[0048] (3) Alternatively, the non-oriented electromagnetic steel plate described in (1) or (2) above may have an insulating film on the surface of the base material.

[0049] (4) Another embodiment of the present invention provides a method for manufacturing a non-oriented electromagnetic steel sheet, which is a method for manufacturing a non-oriented electromagnetic steel sheet as described in any one of (1) to (3) above, wherein,

[0050] For steel ingots, proceed in sequence:

[0051] Hot rolling process,

[0052] A single cold rolling process reduces the plate thickness to below 1.0 mm.

[0053] The intermediate annealing process has a soaking temperature of 800–1050℃ and a soaking time of 1–300 seconds. The secondary cold rolling process has a reduction rate of 65% or more but less than 85%.

[0054] The final annealing process involves annealing at a temperature of 850–1050℃.

[0055] The chemical composition of the steel ingot, expressed as a percentage by mass, is:

[0056] C: 0~0.0050%

[0057] Si: 3.8-4.9%

[0058] Mn: 0.05~1.20%

[0059] sol.Al: Above 0.02%, below 0.50%,

[0060] P: 0–0.030%

[0061] S: 0~0.0030%

[0062] N: 0~0.0030%

[0063] Ti: 0% or more, less than 0.0050%

[0064] Nb: 0% or more, less than 0.0050%

[0065] Zr: 0% or more, less than 0.0050%

[0066] V: Above 0%, less than 0.0050%

[0067] Cu: 0% or more, less than 0.200%

[0068] Ni: 0% or more, less than 0.500%

[0069] Sn: 0~0.100%

[0070] Sb: 0–0.100%, and

[0071] Remaining components: Fe and impurities.

[0072] And satisfy the following equation (i),

[0073] 4.3≤Si+sol.Al+0.5×Mn≤5.0···(i)

[0074] In equation (i) above, the element symbols represent the content (mass%) of each element.

[0075] Invention Effects

[0076] According to the above embodiments of the present invention, non-oriented electromagnetic steel sheets with high strength and excellent magnetic properties can be stably obtained. Detailed Implementation

[0077] In order to solve the above problems, the inventors conducted in-depth research and obtained the following understanding.

[0078] Si, Mn, and sol.Al are elements that increase the electrical resistance of steel, thereby reducing eddy current losses. Furthermore, these elements also contribute to increasing the strength of steel.

[0079] Among Si, Mn, and SOl.Al, Si is the most efficient element in increasing resistance and strength. SOl.Al is second only to Si, also having an effect on increasing resistance and strength. On the other hand, Mn is slightly less effective at increasing resistance and strength compared to Si and SOl.Al.

[0080] Based on these factors, in this embodiment, by adjusting the contents of Si, SOl.Al, and Mn to an appropriate range, high strength and improved magnetic properties are achieved.

[0081] Next, the improvement of toughness during cold rolling of a large number of steel plates containing the above-mentioned Si, Sol.Al and Mn was studied.

[0082] Previously, in pursuit of high strength in steel, the inclusion of large amounts of alloying elements such as Si, Sodium, Al, and Mn in the steel resulted in reduced toughness, leading to increased susceptibility to fracture during cold rolling. Therefore, the inventors of this invention focused on improving the toughness of high-alloy steel sheets during cold rolling. They discovered that by omitting the annealing process for hot-rolled sheets, even high-alloy steels can suppress fracture during cold rolling. Specifically, they mastered a method where, after pickling, the thickness of a hot-rolled sheet is cold-rolled to less than 1 mm in a single pass, followed by intermediate annealing, and then a second cold rolling. This ensures toughness even in high-alloy steels during the second cold rolling process.

[0083] Regarding the secondary cold rolling method, research has been conducted to date. For example, attempts to achieve excellent magnetic properties and high strength have been made in patent documents 3-5.

[0084] However, in the method disclosed in Patent Document 3, the Gaussian orientation {110}<001> is significantly developed, and the magnetic flux density B in the rolling direction is... 50 Good, but B 50 The anisotropy will become excessively large. When B 50 When electromagnetic steel plates with high anisotropy are used in motor cores, they can hinder the smooth rotation of the motor. Regarding the method disclosed in Patent Document 4, because the content of Si, Mn, and Al is low, it cannot satisfy the viewpoint of high strength. In the method disclosed in Patent Document 5, it is possible to make B... 50 The anisotropy is reduced, but the reduction rate of the final cold rolling needs to be higher than 85%. Therefore, the plate thickness at the beginning of the final cold rolling needs to be thicker. The toughness is insufficient, and when the Si content is high, there is a risk of breakage during rolling.

[0085] Therefore, the inventors conducted further and repeated studies, and found that in order to achieve excellent toughness, high strength, and good magnetic properties during cold rolling, and thus B 50 For non-oriented electromagnetic steel sheets with relatively low anisotropy, it is important to properly control the SOl.Al content, the sheet thickness at the start of secondary cold rolling, and the reduction rate of secondary cold rolling.

[0086] This invention is based on the above understanding. Hereinafter, preferred embodiments of the invention will be described in detail. However, the invention is not limited to the configuration disclosed in these embodiments, and various modifications can be made without departing from the spirit of the invention.

[0087] 1. Overall Composition

[0088] The non-oriented electromagnetic steel sheet of this embodiment has high strength and excellent magnetic properties, making it preferred for both stators and rotors. In the manufacturing of the non-oriented electromagnetic steel sheet of this embodiment, its excellent toughness during cold rolling suppresses breakage during rolling, thus enabling stable manufacturing. Furthermore, it is preferable that the non-oriented electromagnetic steel sheet of this embodiment has an insulating film on the surface of the base material (silicon steel sheet) described below.

[0089] 2. Chemical composition of the parent material

[0090] The reasons for limiting the chemical composition of each element in the base material of the non-oriented electromagnetic steel sheet of this embodiment are as follows. Furthermore, in the following description, "%" for content means "mass %". For numerical ranges enclosed in "~", both the lower and upper limits are included within that range.

[0091] C: 0~0.0050%

[0092] Carbon (C) is an element that causes deterioration of iron loss in non-oriented electromagnetic steel sheets. When the C content exceeds 0.0050%, the iron loss of the non-oriented electromagnetic steel sheet deteriorates, and good magnetic properties cannot be obtained. Therefore, the C content is set to 0.0050% or less. Preferably, the C content is 0.0040% or less, more preferably 0.0035% or less, and even more preferably 0.0030% or less. The C content can also be 0%. However, since it is difficult to achieve a C content of 0% in practical steel sheets during manufacturing, the C content can also be set to more than 0%. In addition, since C contributes to the high strength of non-oriented electromagnetic steel sheets, it is preferable that the C content is 0.0005% or more, more preferably 0.0010% or more, to achieve this effect.

[0093] Si: 3.8–4.9%

[0094] Silicon (Si) is an element that increases the electrical resistance of steel, thereby reducing eddy current losses and improving high-frequency iron losses in non-oriented electromagnetic steel sheets. Furthermore, Si has a high solid solution strengthening ability, thus it is also effective for increasing the strength of non-oriented electromagnetic steel sheets. To achieve these effects, the Si content is set to 3.8% or more. Preferably, the Si content is 3.9% or more, more preferably, more than 4.0%, and even more preferably, 4.1% or more. On the other hand, when the Si content is excessive, the processability deteriorates significantly, and cold rolling becomes difficult. Therefore, the Si content is set to 4.9% or less. Preferably, the Si content is 4.8% or less, more preferably, 4.7% or less.

[0095] Mn: 0.05~1.20%

[0096] Manganese (Mn) is an effective element for increasing the resistance of steel, thereby reducing eddy current losses and improving the high-frequency iron losses of non-oriented electromagnetic steel sheets. However, when the Mn content is too low, not only is the increase in resistance less pronounced, but fine sulfides (MnS) precipitate into the steel, sometimes resulting in insufficient grain growth during final annealing. Therefore, the Mn content is set to 0.05% or more. Preferably, the Mn content is 0.20% or more, more preferably 0.23% or more, and even more preferably 0.40% or more. On the other hand, when the Mn content is excessive, the decrease in magnetic flux density of the non-oriented electromagnetic steel sheet becomes significant. Therefore, the Mn content is set to 1.20% or less. Preferably, the Mn content is 1.10% or less, more preferably 1.00% or less.

[0097] sol.Al: Above 0.02%, below 0.50%

[0098] Sodium Al (aluminum) is an element that reduces eddy current losses by increasing the electrical resistance of steel and improves the high-frequency iron losses of non-oriented electromagnetic steel sheets. Furthermore, while not as strong as silicon, sodium Al contributes to the high strength of non-oriented electromagnetic steel sheets due to solid solution strengthening. To achieve these effects, the sodium Al content is set to more than 0.02%. Preferably, the sodium Al content is 0.05% or more, 0.10% or more, or 0.15% or more, and more preferably 0.20% or more. On the other hand, when the sodium Al content is excessive, the anisotropy of the magnetic flux density of the non-oriented electromagnetic steel sheet increases. Therefore, the sodium Al content is set to 0.50% or less. Preferably, the sodium Al content is 0.45% or less, more preferably 0.40% or less, and even more preferably 0.35% or less.

[0099] In addition, in this embodiment, sol.Al means acid-soluble Al and refers to Al that exists in the steel in a solid solution state.

[0100] In this embodiment, the resistivity of the steel is ensured by appropriately controlling the contents of Si, sol.Al, and Mn. Furthermore, from the viewpoint of ensuring strength, it is also necessary to appropriately control the contents of Si, sol.Al, and Mn. On the other hand, from the viewpoint of ensuring magnetic flux density and toughness, an upper limit on the total contents of Si, sol.Al, and Mn is also necessary. Therefore, in addition to the contents of Si, sol.Al, and Mn being within the aforementioned ranges, it is also necessary to satisfy the following formula (i). Regarding the intermediate value of the following formula (i), from the viewpoint of ensuring the resistivity and strength of the steel, it is preferably 4.4 or more, and more preferably 4.5 or more. On the other hand, regarding the intermediate value of the following formula (i), from the viewpoint of ensuring the magnetic flux density and toughness of the steel, it is preferably 4.9 or less, and more preferably 4.8 or less.

[0101] 4.3≤Si+sol.Al+0.5×Mn≤5.0···(i)

[0102] In the above formula, the element symbols represent the content (mass%) of each element.

[0103] P: 0–0.030%

[0104] Phosphorus (P) is included as an impurity in steel, and when its content is excessive, the toughness of the non-oriented electromagnetic steel sheet will be significantly reduced. Therefore, the P content is set to 0.030% or less. Preferably, the P content is 0.025% or less, more preferably 0.020% or less. The P content can also be 0%. Furthermore, since extremely low P content can sometimes lead to increased manufacturing costs, preferably, the P content is 0.003% or more, more preferably 0.005% or more.

[0105] S: 0~0.0030%

[0106] Sulfur (S) is an element that increases iron loss and degrades the magnetic properties of non-oriented electromagnetic steel sheets by forming fine precipitates of MnS. Therefore, the S content is set to 0.0030% or less. Regarding the S content, it is preferable to be 0.0020% or less, more preferably 0.0018% or less, and even more preferably 0.0015% or less. The S content can also be 0%. Furthermore, since extremely low S content can sometimes lead to increased manufacturing costs, it is preferable to have an S content of 0.0001% or more, more preferably 0.0003% or more, and even more preferably 0.0005% or more.

[0107] N: 0~0.0030%

[0108] Nitrogen (N) is an element that inevitably mixes into steel, and it forms nitrides, increasing iron loss and deteriorating the magnetic properties of non-oriented electromagnetic steel sheets. Therefore, the N content is set to 0.0030% or less. Regarding the N content, it is preferable to be 0.0025% or less, and more preferably 0.0020% or less. The N content can also be 0%. Furthermore, since drastically reducing the N content can sometimes increase manufacturing costs, the N content is preferably 0.0005% or more.

[0109] Ti: 0% or more, less than 0.0050%

[0110] Titanium (Ti) is an element that inevitably mixes into steel and can combine with carbon or nitrogen to form precipitates (carbides, nitrides). When carbides or nitrides form, these precipitates themselves degrade the magnetic properties of the non-oriented electromagnetic steel sheet. Furthermore, grain growth during final annealing is hindered by carbides or nitrides, further degrading the magnetic properties of the non-oriented electromagnetic steel sheet. Therefore, the Ti content is set to be less than 0.0050%. Regarding the Ti content, it is preferable to be 0.0040% or less, more preferably 0.0030% or less, and even more preferably 0.0020% or less. The Ti content can also be 0%. However, since drastically reducing the Ti content can sometimes increase manufacturing costs, the Ti content is preferably 0.0005% or more.

[0111] Nb: Above 0%, less than 0.0050%

[0112] Niobium (Nb) is an element that contributes to high strength by combining with carbon or nitrogen to form precipitates (carbides, nitrides), but these precipitates themselves degrade the magnetic properties of non-oriented electromagnetic steel sheets. Therefore, the Nb content is set to less than 0.0050%. Regarding the Nb content, it is preferably 0.0040% or less, more preferably 0.0030% or less, and even more preferably 0.0020% or less. Furthermore, the Nb content is further preferably below the detection limit, specifically, more preferably less than 0.0001%. Since lower Nb content is better, the Nb content can also be set to 0%.

[0113] Zr: 0% or more, less than 0.0050%

[0114] Zirconium (Zr) is an element that contributes to high strength by combining with carbon or nitrogen to form precipitates (carbides, nitrides), but these precipitates themselves degrade the magnetic properties of non-oriented electromagnetic steel sheets. Therefore, the Zr content is set to less than 0.0050%. Regarding the Zr content, it is preferable to be 0.0040% or less, more preferably 0.0030% or less, and even more preferably 0.0020% or less. Furthermore, the Zr content is further preferably below the test limit, specifically, even more preferably 0.0001% or less. Since a lower Zr content is better, the Zr content can also be set to 0%.

[0115] V: Above 0%, less than 0.0050%

[0116] Vanadium (V) is an element that contributes to high strength by combining with carbon or nitrogen to form precipitates (carbides, nitrides), but these precipitates themselves degrade the magnetic properties of non-oriented electromagnetic steel sheets. Therefore, the V content is set to less than 0.0050%. Regarding the V content, it is preferably 0.0040% or less, more preferably 0.0030% or less, and even more preferably 0.0020% or less. The V content is further preferably below the detection limit, specifically, even more preferably 0.0001% or less. Since lower V content is better, the V content can also be set to 0%.

[0117] Cu: 0% or more, less than 0.200%

[0118] Copper (Cu) is an element that inevitably mixes into steel. Intentionally including Cu increases the manufacturing cost of non-oriented electromagnetic steel sheets. Therefore, in this embodiment, it is not necessary to actively include Cu; it can be included at an impurity level. The Cu content is set to the maximum value that can be unavoidably mixed into during the manufacturing process, i.e., less than 0.200%. Regarding the Cu content, it is preferably 0.150% or less, more preferably 0.100% or less. The Cu content can also be 0%. Furthermore, the lower limit of the Cu content is not particularly limited, but drastic reductions in Cu content can sometimes increase manufacturing costs. Therefore, regarding the Cu content, it is preferably 0.001% or more, more preferably 0.003% or more, and even more preferably 0.005% or more.

[0119] Ni: 0% or more, less than 0.500%

[0120] Ni (Ni) is an element that inevitably mixes into steel. However, Ni is also an element that increases the strength of non-oriented electromagnetic steel sheets, so it can be intentionally included. However, Ni has a high price, so the Ni content is set to be less than 0.500%. Regarding the Ni content, it is preferable to be 0.400% or less, more preferably 0.300% or less. The Ni content can also be 0%. Furthermore, the lower limit of the Ni content is not particularly limited, but drastic reductions in Ni content can sometimes increase manufacturing costs. Therefore, regarding the Ni content, it is preferable to be 0.001% or more, more preferably 0.003% or more, and even more preferably 0.005% or more.

[0121] Sn: 0~0.100%

[0122] Sb: 0~0.100%

[0123] Sn (tin) and Sb (antimony) are useful elements in non-oriented electromagnetic steel sheets that help ensure low iron loss by segregating to the surface of the base material and suppressing oxidation and nitriding during annealing. Furthermore, Sn and Sb also have the effect of segregating to grain boundaries, improving texture, and increasing the magnetic flux density of the non-oriented electromagnetic steel sheet. Therefore, at least one of Sn and Sb can be included as needed. However, when the content of these elements is excessive, the toughness of the steel decreases, and cold rolling becomes difficult. Therefore, the content of Sn and Sb is set to 0.100% or less. The content of Sn and Sb is 0.060% or less. The content of Sn and Sb can also be 0%. Furthermore, to reliably obtain the above-mentioned effects, it is preferable to set the content of at least one of Sn and Sb to 0.005% or more, and more preferably 0.010% or more.

[0124] In the chemical composition of the base material (silicon steel sheet) of the non-oriented electromagnetic steel sheet of this embodiment, the remaining part is Fe and impurities. Here, "impurities" refers to components that are mixed in during the industrial manufacturing of steel due to various factors such as raw materials and manufacturing processes, such as ores and waste. This means that they are permissible within a range that will not adversely affect the characteristics of the non-oriented electromagnetic steel sheet of this embodiment.

[0125] Furthermore, the contents of Cr and Mo, as impurity elements, are not specifically specified in this embodiment. In the non-oriented electromagnetic steel sheet of this embodiment, the presence of these elements in amounts of 0.5% or less does not affect the properties of the non-oriented electromagnetic steel sheet. Similarly, the presence of Ca and Mg in amounts of 0.002% or less does not affect the properties of the non-oriented electromagnetic steel sheet. Even the presence of rare earth elements (REM) in amounts of 0.004% or less does not affect the properties of the non-oriented electromagnetic steel sheet. In this embodiment, REM refers to a total of 17 elements, consisting of Sc, Y, and lanthanides, and the aforementioned REM content refers to the total content of these elements.

[0126] O is also an impurity element, but even if it is present in the range of less than 0.05%, it does not affect the properties of the non-oriented electromagnetic steel sheet of this embodiment. O may also be mixed into the steel during the annealing process, so even if it is present in the billet stage (i.e., casting spoon value) in the range of less than 0.01%, it does not affect the properties of the non-oriented electromagnetic steel sheet of this embodiment.

[0127] In addition to the elements mentioned above, Pb, Bi, As, B, Se, etc., can also be included as impurity elements. However, when their respective contents are in the range of 0.0050% or less, they will not impair the characteristics of the non-oriented electromagnetic steel sheet of this embodiment.

[0128] The chemical composition of the base material of the non-oriented electromagnetic steel sheet in this embodiment can be determined by ICP luminescence analysis or spark plug discharge luminescence analysis. Furthermore, C and S can be determined by combustion-infrared absorption method, N can be determined by inert gas combustion-thermal conductivity method, and O can be determined by inert gas melting-non-dispersive infrared absorption method.

[0129] In addition, when the steel plate being measured has an insulating film or the like, its chemical composition is determined after removing the film.

[0130] 3.Magnetic properties

[0131] In the non-oriented electromagnetic steel sheet of this embodiment, "excellent magnetic properties" means that the average iron loss W over the entire cycle is low. 10 / 400 Lower, integer average magnetic flux density B 50 Higher, and B 50 The anisotropy is relatively small. Additionally, the iron loss W... 10 / 400 This means that under conditions of a maximum magnetic flux density of 1.0T and a frequency of 400Hz, the iron loss generated is related to the magnetic flux density B. 50 This means the magnetic flux density in a magnetic field of 5000 A / m.

[0132] The term "whole-cycle average characteristic" refers to the average value of the characteristics in the rolling direction, the characteristics at 45° from the rolling direction, and the characteristics at 90° from the rolling direction, as described below. Furthermore, the term "90° from the rolling direction" means a direction perpendicular to the rolling direction within the plate surface (i.e., a direction perpendicular to both the rolling direction and the plate thickness direction).

[0133] Weekly average W 10 / 400 =(W 10 / 400 (0°)+2×W 10 / 400 (45°)+W 10 / 400 (90°)) / 4

[0134] Weekly average B 50 = (B 50 (0°)+2×B 50 (45°)+B 50 (90°)) / 4

[0135] In addition, B 50 Anisotropy is referred to as ΔB in this specification. 50 To represent, as described below.

[0136] ΔB 50 =B 50 (0°)-B 50 (45°)

[0137] Specifically, "excellent iron loss" refers to the following situation: when the thickness of the non-oriented electromagnetic steel sheet exceeds 0.30mm but is less than 0.35mm, the overall average W... 10 / 400 For values ​​below 16.0 W / kg, when exceeding 0.25 mm but below 0.30 mm, the weekly average W 10 / 400 For values ​​below 15.0 W / kg, when exceeding 0.20 mm but below 0.25 mm, the weekly average W 10 / 400 When the W / kg is below 13.0, and the mm is below 0.20, the weekly average W 10 / 400 Below 12.0 W / kg, independent of plate thickness, ΔB 50 Below 0.16T, the weekly average B 50 For cases where the value is 1.57T or higher. Here, in this embodiment, the aforementioned magnetic characteristics (iron loss W) are... 10 / 400 and magnetic flux density B 50 The measurements were performed using magnetic measuring test pieces in all directions, according to the Epstein test specified in JIS C 2550-1 (2011).

[0138] 4. Mechanical properties

[0139] In the non-oriented electromagnetic steel sheet of this embodiment, "high strength" means that the tensile (maximum) strength in the rolling direction is 580 MPa or more. The tensile strength of the non-oriented electromagnetic steel sheet of this embodiment is 580 MPa or more. Preferably, the tensile strength is 590 MPa or more. Here, the tensile strength is determined by performing a tensile test in accordance with JIS Z 2241 (2011).

[0140] The non-oriented electromagnetic steel sheet according to this embodiment can achieve both high strength and excellent magnetic properties (especially, B). 50 Anisotropy (ΔB) 50 The reduction of strength is not achievable through conventional, simple high-alloying methods. In this embodiment, in addition to the appropriate total content of alloying elements that contribute to strength (Equation (i)), it is also possible to achieve a non-oriented electromagnetic steel sheet that balances high strength and excellent magnetic properties by controlling the conditions of the manufacturing methods described later (especially the secondary cold rolling process and the final annealing process).

[0141] Therefore, the non-oriented electromagnetic steel sheet of this embodiment can be well used as the core material for rotating machines such as drive motors and generators for electric vehicles and hybrid vehicles, as well as compressor motors for air conditioners and large air conditioners.

[0142] 5. Insulating film

[0143] In the non-oriented electromagnetic steel sheet of this embodiment, it is preferable that an insulating film is provided on the surface of the base material. Since the non-oriented electromagnetic steel sheet is stacked after the core blank is punched and then used, the eddy currents between the sheets can be reduced by providing an insulating film on the surface of the base material, and it can also be used as a core to reduce eddy current losses.

[0144] In this embodiment, the type of insulating film is not particularly limited, and known insulating films used as insulating films for non-oriented electromagnetic steel sheets can be used. For example, a composite insulating film that is mainly composed of inorganic materials and contains organic materials can be cited as such an insulating film.

[0145] Here, the term "composite insulating film" refers, for example, to an insulating film primarily composed of at least one of metal salts such as chromate and phosphate, or inorganic substances such as colloidal silica, Zr compounds, and Ti compounds, and containing dispersed fine organic resin particles. In particular, from the viewpoint of reducing the environmental burden during manufacturing, which has become increasingly demanding in recent years, insulating films using coupling agents of metal phosphate, Zr, or Ti as starting materials, or insulating films using carbonates or ammonium salts of coupling agents of metal phosphate, Zr, or Ti as starting materials, are preferred.

[0146] There is no particular limitation on the amount of insulating film applied; for example, it is preferably set at 200–1500 mg / m² per single side. 2 More preferably, it is set at 300–1200 mg / m² per single surface. 2 By forming the insulating film with an adhesion amount within the aforementioned range, excellent uniformity can be maintained. Furthermore, when measuring the adhesion amount of the insulating film afterward, various known measurement methods can be used, such as methods that measure the mass difference before and after immersion in sodium hydroxide aqueous solution, or fluorescence X-ray methods using calibration curves.

[0147] The above description pertains to the non-oriented electromagnetic steel sheet of this embodiment, but the average grain size of the non-oriented electromagnetic steel sheet in this embodiment is not particularly limited. However, if the grain size is not coarsened but the average grain size becomes too small, there is a concern about deterioration of iron loss. On the other hand, if the grain size is excessively coarsened, resulting in an excessively large average grain size, the following issues arise: not only will the strength decrease, but eddy current losses will also worsen. Therefore, it is preferable to set the average grain size of the non-oriented electromagnetic steel sheet to be 50 μm to 120 μm. Alternatively, the average grain size may be set to 60 μm or more, and further, it may be set to 70 μm or more. In addition, the average grain size may be set to 100 μm or less.

[0148] The average crystal grain size can be determined, for example, by the cutting method of JIS G 0551 (2020) in a section parallel to the rolling direction and the thickness direction.

[0149] Furthermore, the thickness of the non-oriented electromagnetic steel sheet in this embodiment is not particularly limited. Generally, although iron loss decreases when the sheet thickness decreases, manufacturing costs increase. Based on this, when the sheet thickness is 0.10 mm or more, iron loss can be further suppressed, and cost increases are also suppressed. In addition, when the sheet thickness is 0.35 mm or less, low iron loss can be maintained. Therefore, the preferred sheet thickness of the non-oriented electromagnetic steel sheet in this embodiment is 0.10 to 0.35 mm. More preferably, it is 0.15 to 0.30 mm.

[0150] 6. Manufacturing method

[0151] Regarding the non-oriented electromagnetic steel sheet of this embodiment, the manufacturing method is not particularly limited, but it can be manufactured by sequentially performing a hot rolling process, a pickling process, a first cold rolling process, an intermediate annealing process, a second cold rolling process, and a final annealing process on a steel ingot having the above-described chemical composition, for example, under the conditions shown below. Furthermore, when an insulating film is formed on the surface of the base material (silicon steel sheet), the insulating film forming process is performed after the aforementioned final annealing process. Each process will be described in detail below.

[0152] <Hot Rolling Process>

[0153] A steel ingot (billet) having the above-described chemical composition is heated, and the heated ingot is hot-rolled to obtain a hot-rolled steel sheet. The heating temperature of the ingot for hot rolling is not particularly limited, but it is preferably set to, for example, 1050–1250°C. Furthermore, the thickness of the hot-rolled steel sheet is not particularly limited, but it is preferably set to, for example, approximately 1.5–3.0 mm, taking into account the efficiency of hot rolling and subsequent processes.

[0154] <Pickling Process>

[0155] After the hot rolling process, pickling is performed without annealing the hot-rolled sheet. Generally, pickling is performed after annealing the hot-rolled sheet following the hot rolling process. However, in the case of steel containing many alloying elements, as in this embodiment, annealing the hot-rolled sheet can lead to a deterioration in toughness, resulting in fracture during cold rolling. Therefore, annealing of the hot-rolled sheet is omitted in this embodiment. Specifically, for the aforementioned hot-rolled sheet, pickling is performed without annealing to remove the oxide scale layer formed on the surface of the base material. Here, the pickling conditions, such as the concentration of the acid used for pickling, the concentration of the pickling accelerator used for pickling, and the temperature of the pickling solution, are not particularly limited and can be set to known pickling conditions.

[0156] <Single Cold Rolling Process>

[0157] After pickling, the sheet thickness is reduced to below 1.0 mm. When the reduced sheet thickness exceeds 1.0 mm, the risk of breakage during secondary cold rolling is high. More preferably, the reduced sheet thickness is below 0.9 mm, and even more preferably, it is below 0.8 mm.

[0158] Intermediate annealing process

[0159] After a single cold rolling process, intermediate annealing is performed to improve the magnetic properties of the non-oriented electromagnetic steel sheet. For the intermediate annealing heat treatment conditions, the sheet is annealed at 800–1050℃ for 1–300 seconds. If the homogenization temperature during intermediate annealing is too low, a circumferentially low magnetic flux density B will occur. 50 To reduce the risk, the homogenization temperature in intermediate annealing is set to 800°C or higher, preferably 850°C or higher, and more preferably 900°C or higher. On the other hand, if the homogenization temperature in intermediate annealing is too high, there is a risk of breakage during secondary cold rolling. Therefore, the homogenization temperature in intermediate annealing is set to 1050°C or lower, preferably 1040°C or lower, and more preferably 1030°C or lower. Furthermore, if the homogenization time in intermediate annealing is too short, there will be an overall average magnetic flux density B. 50 To reduce risks, the soaking time in intermediate annealing is set to 1 second or more, preferably 5 seconds or more, and more preferably 10 seconds or more. On the other hand, if the soaking time in intermediate annealing is too long, there is a risk of increased manufacturing costs. Therefore, the soaking time in intermediate annealing is set to 300 seconds or less, preferably 200 seconds or less, and more preferably 100 seconds or less. In addition, before intermediate annealing, rolling oil from the first cold rolling process may adhere to the surface, so degreasing treatment is preferred.

[0160] <Secondary cold rolling process>

[0161] After the intermediate annealing described above, a second cold rolling process is performed. In this second cold rolling, the final thickness of the base material is 0.10–0.35 mm, and the reduction rate is between 65% and 85%. If the reduction rate in the second cold rolling is too low, a magnetic flux density B will occur. 50 Anisotropy (ΔB) 50There is a risk of increased iron loss. Furthermore, if the reduction rate in the secondary cold rolling is excessively reduced, iron loss may deteriorate. Therefore, it is preferable that the reduction rate in the secondary cold rolling is 67% or higher. On the other hand, if the reduction rate in the secondary cold rolling is too high, there is a risk that the plate thickness at the start of rolling may increase and break. Therefore, it is preferable that the reduction rate in the secondary cold rolling is 83% or lower. Additionally, if intermediate annealing is performed in an oxidizing atmosphere, it is preferable to perform the secondary cold rolling after removing the oxide scale.

[0162] <Final Annealing Process>

[0163] After the aforementioned secondary cold rolling, a final annealing is performed. In the manufacturing method of the non-oriented electromagnetic steel sheet of this embodiment, a continuous annealing furnace is preferably used for the final annealing.

[0164] Here, for the final annealing conditions, the soaking temperature (annealing temperature) is set to 850–1050°C. Furthermore, as other conditions for the final annealing process, it is preferable to set the soaking time to 1–300 sec, to use a mixed atmosphere of H2 and N2 with an H2 content of 5–100 vol% (i.e., H2 + N2 = 100 vol%), and to set the dew point of the atmosphere to 30°C or below.

[0165] When the soaking temperature is below 850°C, the crystal grain size becomes finer, and the iron loss of the non-oriented electromagnetic steel sheet deteriorates, which is therefore not preferred. When the soaking temperature exceeds 1050°C, the strength of the non-oriented electromagnetic steel sheet is insufficient, leading to an increase in manufacturing costs, which is also not preferred. Regarding the soaking temperature, 875–1025°C is more preferred, and 900–1000°C is even more preferred. When the soaking time is less than 1 second, the grains cannot be sufficiently coarsened. When the soaking time exceeds 300 seconds, it leads to an increase in manufacturing costs. Regarding the proportion of H2 in the atmosphere, 10–90% by volume is more preferred. Regarding the dew point of the atmosphere, a lower dew point is preferred from the viewpoint of increasing magnetic flux density. Regarding the dew point of the atmosphere, 10°C or less is more preferred, 0°C or less is even more preferred, and -10°C or less is even more preferred.

[0166] <Insulating film formation process>

[0167] After the final annealing described above, an insulating film forming process is performed as needed. The method for forming the insulating film is not particularly limited; a treatment solution for forming a known insulating film as described below can be used, and the solution can be coated and dried using known methods. Examples of known insulating films include composite insulating films that are primarily inorganic and also contain organic materials.

[0168] Composite insulating films, for example, refer to insulating films primarily composed of metal salts such as chromate and phosphate, or inorganic substances such as colloidal silica, Zr compounds, and Ti compounds, and containing dispersed fine organic resin particles. In particular, from the viewpoint of reducing the environmental burden during manufacturing, which has become increasingly important in recent years, insulating films using coupling agents of metal phosphate, Zr, or Ti as starting materials, or insulating films using carbonates or ammonium salts of coupling agents of metal phosphate, Zr, or Ti as starting materials, are preferred.

[0169] Alternatively, the surface of the base material forming the insulating film may undergo any pretreatment, such as degreasing based on alkali or pickling based on hydrochloric acid, sulfuric acid, phosphoric acid, etc., before applying the coating solution. Alternatively, the coating solution may be applied to the surface of the base material in its final annealed state without performing these pretreatments.

[0170] The present invention will be described in more detail below through embodiments. However, the conditions in the embodiments are merely examples used to confirm the feasibility and effects of the present invention, and the present invention is not limited to these examples. Various conditions can be used to achieve the purpose of the present invention without departing from its spirit.

[0171] Example 1

[0172] A steel billet with the composition shown in Table 1 was heated to 1150°C, then hot-rolled to a final temperature of 850°C and a final thickness of 2.0 mm, and coiled at 650°C to produce a hot-rolled steel sheet. The obtained hot-rolled steel sheet was then subjected to a first cold rolling process to a thickness of 0.7 mm after removing the surface oxide scale by pickling without hot rolling annealing. Next, the cold-rolled steel sheet was degreased and then intermediate annealed at 970°C for 40 seconds to obtain an intermediate-annealed sheet. The intermediate-annealed sheet was then subjected to a second cold rolling process to a thickness of 0.20 mm to produce a cold-rolled steel sheet. Finally, a final annealing was performed at 1000°C for 20 seconds in a mixed atmosphere of H2:15%, N2:85%, and dew point -30°C. An insulating film was then coated to manufacture a non-oriented electromagnetic steel sheet, which was used as experimental material.

[0173] Furthermore, the aforementioned insulating film is formed by means of an adhesion amount of 1000 mg / m 2 An insulating film composed of aluminum phosphate and styrene-acrylic copolymer resin emulsion with a particle size of 0.2 μm is coated and sintered in the atmosphere at 350°C.

[0174] [Table 1]

[0175]

[0176] [Table 2]

[0177]

[0178] The underlined part indicates that the invention is outside the scope of this invention.

[0179] For each of the obtained test materials, Epstein test pieces were collected from the rolling direction, at a 45° angle from the rolling direction, and at a 90° angle from the rolling direction. The magnetic properties (iron loss W) in each direction were measured using the Epstein test according to JIS C 2550-1 (2011). 10 / 400 and magnetic flux density B 50 An evaluation was conducted. The weekly average iron loss W was calculated. 10 / 400 The average magnetic flux density B over the entire cycle is below 12.0 W / kg. 50 It is above 1.57T, and ΔB 50 A magnetic strength of 0.16T or less is considered excellent and thus deemed acceptable. Failure to meet this condition is considered poor and thus deemed unacceptable. Furthermore, this acceptance condition is established because the final thickness of the cold-rolled material in each test is 0.20mm or less.

[0180] Furthermore, JIS No. 5 tensile test pieces were collected from various test materials according to JIS Z 2241 (2011), with the length direction aligned with the rolling direction of the steel plate. Tensile tests were then conducted on these test pieces according to JIS Z 2241 (2011), and the tensile strength was determined. A tensile strength of 580 MPa or higher was considered high strength and thus deemed acceptable. A tensile strength less than 580 MPa was considered poor strength and thus deemed unacceptable.

[0181] The results of the Epstein test and tensile test described above are shown in Table 2. Additionally, underlines in Tables 1 and 2 indicate compositions outside the scope of this invention. Furthermore, the "-" in the chemical composition table shown in Table 1 indicates that the corresponding element content is 0% in the significant figures (to the smallest digit) specified in this embodiment.

[0182] In tests No. 2-4, 6, 7, 9, 12-14 and 16-18, which specify the chemical composition of the steel plate to meet the requirements of this invention, it can be seen that: the circumferential average iron loss is low, the circumferential average magnetic flux density is high, the magnetic flux density anisotropy is small, and it has a high tensile strength of 580 MPa or more.

[0183] In contrast, in comparative tests No. 1, 5, 8, 10, 11, 15 and 19-23, at least one of the magnetic properties and tensile strength was poor or the toughness was significantly deteriorated, making manufacturing difficult.

[0184] Specifically, in Test No. 1, the Si content was below the specified range, resulting in poor tensile strength. Furthermore, in Test No. 8, because equation (i) was not satisfied, the tensile strength was also poor.

[0185] In Test No. 5, equation (i) was not satisfied. In Test No. 15, the P content exceeded the specified range, resulting in deteriorated toughness and fracture during cold rolling, making it impossible to measure tensile strength and magnetic properties. Similarly, in Test No. 20, the Si content and equation (i) were not satisfied. In Test No. 22, the Sn content exceeded the specified range. Furthermore, in Test No. 23, the Sb content exceeded the specified range, resulting in deteriorated toughness and fracture during cold rolling, making it impossible to measure tensile strength and magnetic properties.

[0186] In test No. 10, the SAl content exceeded the specified range, resulting in poor anisotropy of magnetic flux density. In test No. 11, the S content exceeded the specified range, resulting in poor iron loss. In test No. 19, the C content exceeded the specified range, resulting in poor iron loss. In test No. 21, the SAl content was below the specified range, resulting in poor iron loss.

[0187] Example 2

[0188] After heating the steel billet of steel grade I in Table 1 to 1150°C, it was hot-rolled at a final temperature of 850°C and a final thickness of 2.0 mm, and then coiled at 650°C to produce a hot-rolled steel sheet. The obtained hot-rolled steel sheet was then subjected to pickling to remove the surface oxide scale without hot-rolling annealing, and then pressed down to the thickness shown in Table 3 to obtain a primary cold-rolled sheet. After degreasing the primary cold-rolled sheets of various thicknesses, they were subjected to intermediate annealing for 30 seconds at the homogenization temperature shown in Table 3 to obtain an intermediate annealed sheet. The intermediate annealed sheet was then subjected to secondary cold rolling to a thickness of 0.20 mm to produce a cold-rolled steel sheet. Finally, a final annealing was performed for 20 seconds at the homogenization temperature shown in Table 3 in a mixed atmosphere of H2:15%, N2:85%, and dew points shown in Table 3. Then, an insulating film was coated to manufacture a non-oriented electromagnetic steel sheet, which was used as the test material. In addition, as shown in Experiment No. 40, a comparative example was also carried out by annealing hot-rolled plates with the heat homogenization conditions set at 950°C for 60 seconds.

[0189] [Table 3]

[0190]

[0191] Furthermore, the aforementioned insulating film is formed by means of an adhesion amount of 900 mg / m 2An insulating film composed of aluminum phosphate and styrene-acrylic copolymer resin emulsion with a particle size of 0.2 μm is coated and sintered in the atmosphere at 350°C.

[0192] For each of the obtained test materials, Epstein test pieces were collected from the rolling direction, at a 45° angle from the rolling direction, and at a 90° angle from the rolling direction. The magnetic properties (iron loss W) in each direction were measured using the Epstein test according to JIS C 2550-1 (2011). 10 / 400 and magnetic flux density B 50 An evaluation was conducted. The weekly average iron loss W was calculated. 10 / 400 The average magnetic flux density B over the entire cycle is below 12.0 W / kg. 50 It is above 1.57T, and ΔB 50 A magnetic strength of 0.16T or less is considered excellent and thus deemed acceptable. Failure to meet this condition is considered poor and thus deemed unacceptable. Furthermore, this acceptance condition is set because the thickness of each test material is 0.20mm or less.

[0193] Furthermore, JIS No. 5 tensile test pieces were collected from various test materials according to JIS Z 2241 (2011), with the length direction aligned with the rolling direction of the steel plate. Tensile tests were then conducted on these test pieces according to JIS Z 2241 (2011), and the tensile strength was determined. A tensile strength of 580 MPa or higher was considered high strength and thus deemed acceptable. A tensile strength less than 580 MPa was considered poor strength and thus deemed unacceptable.

[0194] The results of the Epstein test and the tensile test are shown together in Table 3.

[0195] In tests No. 25-27, 30-32 and 36-38, which meet the requirements of this invention regarding the plate thickness after one cold rolling, intermediate annealing temperature and reduction rate of the second cold rolling, it can be seen that: the circumferential average iron loss is low, the circumferential average magnetic flux density is high, the anisotropy of magnetic flux density is small, and it has a high tensile strength of over 580 MPa.

[0196] In contrast, in comparative tests No. 24, 28, 29, 33-35 and 39-41, the magnetic properties were poor, the tensile strength was poor, or the toughness was significantly deteriorated, making manufacturing difficult.

[0197] Specifically, in tests No. 24 and 41, the sheet thickness after the first cold rolling was greater than the specified range, resulting in decreased toughness and fracture during the second cold rolling, making it impossible to measure tensile strength and magnetic properties. In test No. 33, the intermediate annealing temperature was higher than the specified range, resulting in decreased toughness and fracture during the second cold rolling, making it impossible to measure tensile strength and magnetic properties. Furthermore, in test No. 40, hot-rolled sheet annealing was performed, resulting in decreased toughness and fracture during the first cold rolling, making it impossible to measure tensile strength and magnetic properties.

[0198] Furthermore, in Experiment No. 28, the reduction rate of the second cold rolling was lower than the specified range, resulting in poor anisotropy of magnetic flux density. Also, in Experiment No. 29, the intermediate annealing temperature was lower than the specified range, resulting in poor overall average magnetic flux density.

[0199] Furthermore, in Test No. 34, the final annealing temperature was lower than specified, resulting in a poorer average iron loss over the entire cycle. On the other hand, in Test No. 35, the final annealing temperature was higher than specified, resulting in a poorer tensile strength.

[0200] In Experiment No. 39, the reduction rate of the second cold rolling was lower than the specified range, and the final annealing temperature was also lower than the specified range, resulting in poor iron loss.

[0201] Industrial availability

[0202] As described above, according to the present invention, it is possible to obtain non-oriented electromagnetic steel sheets with high strength and excellent magnetic properties.

Claims

1. A non-oriented electromagnetic steel sheet, wherein, The chemical composition of the base material, expressed as a percentage by mass, is: C：0～0.0050%、 Si: 3.8–4.9% Mn: 0.05~1.20%, sol.Al: above 0.02%, below 0.50%, P：0～0.030％、 S：0～0.0030％、 N：0～0.0030％、 Ti: 0% or more, less than 0.0050% Nb: 0% or more, less than 0.0050% Zr: 0% or more, less than 0.0050% V: Above 0%, less than 0.0050% Cu: 0% or more, less than 0.200% Ni: 0% or more, less than 0.500% Sn: 0~0.100% Sb: 0–0.100%, and Remaining components: Fe and impurities; It satisfies the following equations (i) to (iii); Tensile strength above 580MPa 4.3≤Si+sоl.Al+0.5×Mn≤5.0・・・(i) In equation (i) above, the element symbols represent the content of each element in terms of mass%. B 50 (0°)-B 50 (45°)≤0.16・・・(ii) (B 50 (0°)+2×B 50 (45°)+B 50 (90°)) / 4≥1.57・・・(iii) Wherein, B in equations (ii) and (iii) above 50 (0°) represents the magnetic flux density (T) under a magnetizing force of 5000 A / m in the rolling direction, and B 50 (45°) represents the magnetic flux density (T) at a magnetization force of 5000 A / m at a 45° angle from the rolling direction, and B 50 (90°) is the magnetic flux density (T) at a magnetization force of 5000 A / m at a direction 90° away from the rolling direction. The thickness of non-oriented electromagnetic steel sheets is 0.1~0.35mm. When the thickness of the non-oriented electromagnetic steel sheet exceeds 0.30mm but is less than 0.35mm, the whole-cycle average W 10 / 400 For values ​​below 16.0 W / kg, when exceeding 0.25 mm but below 0.30 mm, the weekly average W 10 / 400 For values ​​below 15.0 W / kg, when exceeding 0.20 mm but below 0.25 mm, the weekly average W 10 / 400 When the W / kg is below 13.0, and the mm is below 0.20, the weekly average W 10 / 400 It is below 12.0 W / kg.

2. The non-oriented electromagnetic steel sheet as described in claim 1, wherein, The chemical composition, expressed as a percentage by mass, contains from Sn: 0.005–0.100%, and Sb: 0.005~0.100% Choose one or two from them.

3. The non-oriented electromagnetic steel sheet as described in claim 1 or 2, wherein, The surface of the base material has an insulating film.

4. A method for manufacturing a non-oriented electromagnetic steel sheet, comprising the method for manufacturing a non-oriented electromagnetic steel sheet as described in any one of claims 1 to 3, wherein, For steel ingots, proceed in sequence: Hot rolling process, A single cold rolling process reduces the plate thickness to below 1.0 mm. The intermediate annealing process involves a soaking temperature of 800–1050℃ and a soaking time of 1–300 seconds. The secondary cold rolling process has a reduction rate of 65% or more but less than 85%, and The final annealing process involves annealing at a temperature of 850–1050℃. After the hot rolling process, the hot-rolled plate is not annealed.

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