Non-oriented electromagnetic steel sheet

Abstract

This non-oriented electromagnetic steel sheet includes a steel sheet having a predetermined chemical composition comprising, in mass %: C: 0.0030% or less, Si: 1.40-3.50%, Al: 0.10-2.00%, Mn: 0.10-2.00%, P: 0.18% or less, S: 0.0030% or less, N is N: 0.0030% or less, Ti: 0.0030% or less, B: 0.0020% or less, Sn: 0-0.20%, and Sb: 0-0.100%, with the remainder being Fe and impurities. When the plate width of the steel plate is defined as W, the length of the steel plate as L, and the region from one end in the longitudinal direction of the steel plate to L / 10 as a TL portion, of the number density of precipitates having a grain size in the range of 0.05-0.50 μm at the center in the thickness direction of the steel plate in a W / 10 portion, a W / 4 portion, and a W / 2 portion, the maximum value is defined as DWmax and the minimum value as DWmin, wherein the ratio fW of DWmax to DWmin, or fW = DWmax / DWmin, is 5.0 or less.

Description

Non-oriented electrical steel sheet

[0001] This application claims priority to Japanese Patent Application No. 2024-035777, filed on March 8, 2024, the contents of which are incorporated herein by reference.

[0002] In the field of motors, especially in the field of electrical equipment such as compressors for air conditioners and refrigerators, small and medium-sized transformers, and electrical components, there is a need to reduce power consumption, energy consumption, and CO2 emissions worldwide. ２ With the movement to protect the global environment, such as reducing emissions, there is an ever-increasing demand for more efficient and smaller motors.

[0003] In the automotive field, Japanese automakers have publicly announced their intention to increase production of electric vehicles, such as hybrid vehicles and electric vehicles, which are driven by motors. Non-oriented electrical steel sheets are used for the cores of the drive motors of these electric vehicles, and as a result, demand for non-oriented electrical steel sheets is growing significantly. In this context, improving the magnetic properties of non-oriented electrical steel sheets used as motor core materials and mass-producing them are of utmost importance.

[0004] There are methods for improving the magnetic properties of non-oriented electrical steel sheets, such as adding alloy elements such as Si and reducing impurity elements such as C, S, and N. In addition, there are methods for achieving mass production by simplifying the manufacturing process, and for example, if hot-rolled sheet annealing is a bottleneck in manufacturing, mass production can be achieved by omitting the hot-rolled sheet annealing.

[0005] However, if hot-rolled sheet annealing is omitted, the differences in impurities present in the longitudinal and transverse directions of the coil at the end of hot rolling will not be tempered by hot-rolled sheet annealing, resulting in variations in the magnetic properties of the non-oriented electrical steel sheet (product sheet) manufactured in the subsequent process. Such variations can cause deviations in the flow of magnetic flux when the product sheets are laminated to manufacture a motor, resulting in poor magnetic properties of the motor. For this reason, it is necessary to minimize the variations in magnetic properties within the coil.

[0006] Patent Document 1 discloses a non-oriented electrical steel sheet with low iron loss after magnetic annealing, in which the S content is controlled to an extremely small amount of 10 ppm or less (including 0) and the Ti content is controlled to an extremely small amount of 50 ppm or less (including 0). However, Patent Document 1 does not mention a means for reducing the deviation of magnetic properties within a coil. As a technology for reducing the deviation of magnetic properties within a coil, Patent Document 2 discloses a manufacturing method for a non-oriented electrical steel sheet with small fluctuations in magnetic properties within a coil. However, with the technology of Patent Document 2, there is a concern that sufficient magnetic properties may not be obtained if hot-rolled sheet annealing is omitted. Furthermore, Patent Documents 1 and 2 control the content of S or Ti to reduce precipitates that affect iron loss. However, there is a concern that the methods of Patent Documents 1 and 2 require a long time for refining in the steelmaking process. Furthermore, Patent Document 2 reduces precipitates by setting the slab heating temperature to 980 to 1140°C, but there is also a concern that the heating time will be long due to the low temperature heating.

[0007] Japanese Unexamined Patent Publication No. 10-88297 Japanese Unexamined Patent Publication No. 2011-256437

[0008] As described above, in the prior art, when hot-rolled sheet annealing is not performed, the variation in magnetic properties within steel sheets, including coils, has not been adequately controlled. Therefore, in addition to having good magnetic properties, there has been a demand for reducing the variation in magnetic properties within non-oriented electrical steel sheets. In particular, because the variation in magnetic properties in the width direction has a significant impact on motor characteristics, there has been a demand for reducing the variation in magnetic properties in the width direction.

[0009] In view of the above demand, the present invention aims to provide a non-oriented electrical steel sheet that is produced without hot-rolled sheet annealing, and that has small deviations in magnetic properties in the width direction and good magnetic properties. Preferably, the present invention aims to provide a non-oriented electrical steel sheet that is produced without hot-rolled sheet annealing, and that has small deviations in magnetic properties in the length direction and width direction and good magnetic properties.

[0010] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that it is possible to reduce the deviation in magnetic properties in non-oriented electrical steel sheets by actively controlling fine precipitates. The present invention has been made based on the above-mentioned findings, and the gist of the present invention is as follows.

[0011] [1] A non-oriented electrical steel sheet according to one aspect of the present invention has a steel sheet, and the chemical composition of the steel sheet is, in mass%, C: 0.0030% or less, Si: 1.40 to 3.50%, Al: 0.10 to 2.00%, Mn: 0.10 to 2.00%, P: 0.18% or less, S: 0.0030% or less, N: 0.0030% or less, Ti: 0.0030% or less, B: 0.0020% or less, Sn: 0 to 0.20%, Sb: 0 to 0.100%, and the balance: Fe and impurities, and the width of the steel sheet is W, and a range of 1 / 20 to 3 / 20 of the sheet width W from an end in the width direction of the steel sheet toward the center in the width direction is W / 10 parts, a range of 4 / 20 to 6 / 20 of the sheet width W is W / 4 parts, and A range of 9 / 20 to 11 / 20 of the plate width is defined as a W / 2 part, the length of the steel plate is defined as L, the range from one end of the steel plate in the longitudinal direction to L / 10 is defined as a TL part, a range from 2 / 5 to 3 / 5 of the length L from the end is defined as an L / 2 part, and a range from 9L / 10 from the end to the other end is defined as an EL part, and in the TL part, among the number densities of precipitates having a particle size in the range of 0.05 to 0.50 μm at the center of the steel plate in the plate thickness direction in the W / 10 part, the W / 4 part, and the W / 2 part, the maximum value is defined as DWmax and the minimum value is defined as DWmin, where fW is the ratio of DWmax to DWmin expressed by the following formula (1), and is 5.0 or less. fW=DWmax / DWmin Formula (1) [2] In the non-oriented electrical steel sheet according to [1], when the maximum value of number densities of precipitates having a grain size in a range of 0.05 to 0.50 μm at the center in the sheet thickness direction in the W / 2 portion, the TL portion, the L / 2 portion, and the EL portion is DLmax, and the minimum value is DLmin, the ratio fL of DLmax to DLmin, which is represented by the following formula (2), may be 5.0 or less:fL=DLmax / DLmin Formula (2) [3] In the non-oriented electrical steel sheet according to [1], when the magnetic flux density B50 is measured at the W / 10 part, the W / 4 part, and the W / 2 part of the TL portion of the steel sheet when excited in a magnetic field of 5000 A / m, and the difference between the maximum value and the minimum value is defined as ΔB50a, and the iron loss W15 / 50 at 50 Hz at a magnetic flux density of 1.5 T is measured, and the difference between the maximum value and the minimum value is defined as ΔW15 / 50a, the ΔB50a may satisfy the following formula (3), and the ΔW15 / 50a may satisfy the following formula (4): ΔB50a (T)≦0.02 ... formula (3) ΔW15 / 50a (W / kg)≦0.4 ... formula (4) [4] The non-oriented electrical steel sheet according to [2] may be such that, when a magnetic flux density B50 is measured at the W / 10 part, the W / 4 part, and the W / 2 part of the TL part of the steel sheet when excited in a magnetic field of 5000 A / m, and the difference between the maximum and minimum values ​​is defined as ΔB50a, and an iron loss W15 / 50 at 50 Hz at a magnetic flux density of 1.5 T is measured, and the difference between the maximum and minimum values ​​is defined as ΔW15 / 50a, ΔB50a satisfies the following formula (3) and ΔW15 / 50a satisfies the following formula (4). ΔB50a (T)≦0.02 ... formula (3) ΔW15 / 50a (W / kg)≦0.4 ... formula (4) [5] In the non-oriented electrical steel sheet according to [2] or [4], when the difference between the maximum and minimum values ​​of magnetic flux density B50 in the TL portion, the L / 2 portion, and the EL portion of the W / 2 portion of the steel sheet when excited in a magnetic field of 5000 A / m is defined as ΔB50b in T, and the difference between the maximum and minimum values ​​of iron loss W15 / 50 in the TL portion, the L / 2 portion, and the EL portion of the steel sheet at 50 Hz and a magnetic flux density of 1.5 T is defined as ΔW15 / 50b value in W / kg, the ΔB50b may satisfy the following formula (5) and the ΔW15 / 50b value may satisfy the following formula (6): ΔB50b≦0.02 Equation (5) ΔW15 / 50b≦0.2 Equation (6) [6] In the non-oriented electrical steel sheet according to any one of [1] to [5], the precipitates may be one or more of AlN, MnS, TiN, and Ti(C,S).[7] In the non-oriented electrical steel sheet according to any one of [1] to [5], when the Sn content in mass% is [Sn] and the Sb content in mass% is [Sb], the chemical composition may satisfy 0.02≦[Sn]+2×[Sb]≦0.20. [8] In the non-oriented electrical steel sheet according to [6], when the Sn content in mass% is [Sn] and the Sb content in mass% is [Sb], the chemical composition may satisfy 0.02≦[Sn]+2×[Sb]≦0.20. [9] In the non-oriented electrical steel sheet according to any one of [1] to [5], the surface of the steel sheet may have an insulating coating.

[10] In the non-oriented electrical steel sheet according to [6], the surface of the steel sheet may have an insulating coating.

[11] In the non-oriented electrical steel sheet according to [7], the surface of the steel sheet may have an insulating coating.

[12] In the non-oriented electrical steel sheet according to [8], an insulating coating may be formed on the surface of the steel sheet.

[0012] According to the above-described aspects of the present invention, it is possible to provide a non-oriented electrical steel sheet having small deviation in magnetic properties in the width direction and having good magnetic properties, even when hot-rolled sheet annealing is not performed.

[0013] 1 is a diagram showing the ratio fW of the number density of precipitates and the difference ΔB50a (unit: T) between the maximum and minimum values ​​of B50 in the width direction of the steel plate; FIG. 2 is a diagram showing the ratio fW of the number density of precipitates and the difference ΔW15 / 50a (unit: W / kg) between the maximum and minimum values ​​of W15 / 50 in the width direction of the steel plate; FIG. 3 is a diagram showing the ratio fL of the number density of precipitates and the difference ΔB50b (unit: T) between the maximum and minimum values ​​of B50 in the length direction of the steel plate; and FIG. 4 is a diagram showing the ratio fL of the number density of precipitates and the difference ΔW15 / 50b (unit: W / kg) between the maximum and minimum values ​​of W15 / 50 in the length direction of the steel plate.

[0014] A non-oriented electrical steel sheet according to one embodiment of the present invention (hereinafter sometimes referred to as "the electrical steel sheet according to this embodiment" or "the non-oriented electrical steel sheet according to this embodiment") and a manufacturing method thereof will be described. In this embodiment, the sheet width of the steel sheet (base steel sheet) of the non-oriented electrical steel sheet is defined as W, and the range from the end of the steel sheet in the width direction (sheet width direction) toward the center in the width direction is defined as W / 10 parts, the range from 1 / 20 to 3 / 20 of the sheet width W (W / 20 to 3W / 20) is defined as W / 4 parts, and the range from 4 / 20 to 6 / 20 of the sheet width W (4W / 20 to 6W / 20) is defined as W / 4 parts, and the range from 9 / 20 to 11 / 20 of the sheet width W (9W / 20 to 11W / 20) is defined as W / 2 parts. The length of the steel sheet (base steel sheet) of the non-oriented electrical steel sheet is defined as L, and the range from one end of the steel sheet in the longitudinal direction to L / 10 is defined as the TL portion, the range from the end to 2 / 5 to 3 / 5 of the length L is defined as the L / 2 portion, and the range from 9L / 10 of the length L from the end to the other end is defined as the EL portion. The range from the surface to 1 / 4 to 3 / 4 of the way through the sheet thickness is defined as the center portion in the sheet thickness direction.

[0015] The electrical steel sheet according to this embodiment has a steel sheet having a predetermined chemical composition, and in the TL portion, when the maximum value of the number density of precipitates having a particle size in the range of 0.05 to 0.50 μm at the center in the sheet thickness direction of the steel sheet in the W / 10 portion, the W / 4 portion, and the W / 2 portion is defined as DWmax and the minimum value is defined as DWmin, fW, which is the ratio of DWmax to DWmin expressed by the following formula (1), is 5.0 or less. fW=DWmax / DWmin Formula (1)

[0016] Furthermore, in the electrical steel sheet according to this embodiment, when the maximum number density of precipitates having a grain size in the range of 0.05 to 0.50 μm at the center in the sheet thickness direction of the W / 2 portion, the TL portion, the L / 2 portion, and the EL portion is DLmax and the minimum number density is DLmin, the ratio fL of DLmax to DLmin, as expressed by the following formula (2), is preferably 5.0 or less: fL=DLmax / DLmin Formula (2)

[0017] Each of these will be explained below.

[0018] [Chemical composition] The types of elements that make up the chemical composition of the steel sheet contained in the electrical steel sheet according to this embodiment and the reasons for limiting their contents will be explained below. The "%" relating to the element content means "mass %." When the electrical steel sheet according to this embodiment is made of steel sheet only (when an insulating coating or the like is not included), the chemical composition of the steel sheet can be said to be the chemical composition of a non-oriented electrical steel sheet.

[0019] C: 0.0030% or less C is an element that causes magnetic aging and increases iron loss. Therefore, the C content is set to 0.0030% or less. The C content is preferably 0.0025% or less, and more preferably 0.0020% or less. There is no lower limit for the C content, and it may be 0%, but excessive reduction of C leads to increased costs, so it is preferable to set it to 0.0005% or more.

[0020] Si: 1.40 to 3.50% Si is an element that increases the electrical resistance of a steel sheet, reduces eddy current loss, and reduces iron loss. If the Si content is less than 1.40%, the electrical resistance of the steel sheet does not increase, and iron loss is not sufficiently reduced. Therefore, the Si content is set to 1.40% or more. The Si content is preferably 1.80% or more, and more preferably 2.00% or more. On the other hand, Si is an element that inhibits improvement of magnetic flux density. Furthermore, Si increases the hardness of the steel sheet, inhibiting workability in cold rolling and other processes during the steel sheet manufacturing process, increasing manufacturing costs and inhibiting punching workability. If the Si content exceeds 3.50%, the magnetic flux density and punching workability will be significantly reduced, and manufacturing costs will increase. Therefore, the Si content is set to 3.50% or less. The Si content is preferably 3.30% or less, and more preferably 3.20% or less.

[0021] Al: 0.10 to 2.00% Al contributes to deoxidation and, like Si, increases electrical resistance, reduces eddy current loss, and reduces iron loss. If the Al content is less than 0.10%, the above effects cannot be obtained, and fine AlN is formed, adversely affecting iron loss. Therefore, the Al content is set to 0.10% or more. The Al content is preferably 0.20% or more, and more preferably 0.50% or more. On the other hand, if the Al content exceeds 2.00%, the saturation magnetic flux density decreases, resulting in a decrease in magnetic flux density. Therefore, the Al content is set to 2.00% or less. The Al content is preferably 1.50% or less, and more preferably 1.20% or less.

[0022] Mn: 0.10 to 2.00% Mn is an element that increases electrical resistance, reduces eddy current loss, and suppresses the precipitation of fine sulfides such as MnS, which are harmful to grain growth. If the Mn content is less than 0.10%, the effect is not sufficiently obtained. Therefore, the Mn content is set to 0.10% or more. The Mn content is preferably 0.20% or more, more preferably 0.40% or more. On the other hand, if the Mn content exceeds 2.00%, the growth of grains during annealing decreases and iron loss increases. Therefore, the Mn content is set to 2.00% or less. The Mn content is preferably 1.50% or less, more preferably 1.20% or less.

[0023] P: 0.18% or less P is an element that reduces the toughness of steel. If the P content exceeds 0.18%, the toughness significantly decreases and the steel plate becomes more susceptible to fracture, so the P content is set to 0.18% or less. The P content is preferably 0.15% or less, and more preferably 0.12% or less. There is no particular restriction on the lower limit of the P content, and it may be 0%, but considering the manufacturing cost, 0.001% is a substantial lower limit. Therefore, the P content may be set to 0.001% or more, or 0.01% or more.

[0024] S: 0.0030% or less S is an element that forms fine sulfides such as MnS and inhibits recrystallization and grain growth during final annealing, etc. If the S content exceeds 0.0030%, recrystallization and grain growth during final annealing, etc. are significantly inhibited. Therefore, the S content is set to 0.0030% or less. The S content is preferably 0.0020% or less, more preferably 0.0015% or less. The lower limit of the S content is not particularly limited and may be 0%, but considering industrial purification technology, the lower limit is 0.0001%, and considering production costs, 0.0003% is a substantial lower limit. Therefore, the S content may be set to 0.0001% or more, or 0.0003% or more.

[0025] N: 0.0030% or less N is an element that forms precipitates and increases iron loss. If the N content exceeds 0.0030%, the increase in iron loss is significant. Therefore, the N content is set to 0.0030% or less. The N content is preferably 0.0020% or less, and more preferably 0.0015% or less. There is no particular restriction on the lower limit of the N content, and it may be 0%, but considering the manufacturing cost, 0.0005% is a substantial lower limit. Therefore, the N content may be set to 0.0005% or more.

[0026] Ti: 0.0030% or less Ti is an element that forms precipitates and increases iron loss. If the Ti content exceeds 0.0030%, the increase in iron loss is significant. Therefore, the Ti content is set to 0.0030% or less. The Ti content is preferably 0.0020% or less, and more preferably 0.0015% or less. There is no particular restriction on the lower limit of the Ti content, and it may be 0%, but considering the manufacturing cost, 0.0005% is the substantial lower limit. Therefore, the Ti content may be set to 0.0005% or more.

[0027] B: 0.0020% or less B is an element that forms precipitates and increases iron loss. If the B content exceeds 0.0020%, the increase in iron loss is significant. Therefore, the B content is set to 0.0020% or less. The B content is preferably 0.0010% or less, and more preferably 0.0005% or less. There is no particular restriction on the lower limit of the B content, and it may be 0%, but considering industrial purification technology, the lower limit is 0.0001%. Therefore, the B content may be set to 0.0001% or more.

[0028] Sn: 0 to 0.20% Sb: 0 to 0.100% [Sn] + 2 × [Sb]: 0.02 to 0.20% Sn and Sb are elements that suppress surface nitriding and contribute to reducing iron loss. Although Sn and Sb are not essential, they may be contained to obtain the above-mentioned effects. To obtain the above-mentioned effects, it is preferable to contain one or both of Sn and Sb in a range that satisfies 0.02 ≦ [Sn] + 2 × [Sb] ≦ 0.20, where [Sn] is the Sn content and [Sb] is the Sb content, in mass %. If [Sn] + 2 × [Sb] is less than 0.02, the effect of improving magnetic properties cannot be obtained. [Sn] + 2 × [Sb] is more preferably 0.05 or greater. On the other hand, if [Sn] + 2 × [Sb] exceeds 0.20, the toughness of the steel sheet deteriorates. Therefore, it is preferable that [Sn] + 2 × [Sb] is 0.20 or less. [Sn] + 2 × [Sb] is more preferably 0.10 or less. The Sn and Sb contents are set to 0.20% or less and 0.100% or less so as to satisfy [Sn] + 2 × [Sb].

[0029] Balance: Fe and impurities In the chemical composition of the steel sheet, the balance excluding the above elements is Fe and impurities. Impurities are elements that are inevitably mixed in from the steel raw materials and / or during the steelmaking process, and are permissible within a range that does not impair the properties of the electrical steel sheet according to this embodiment. The total amount of impurities is preferably 0.50% or less.

[0030] Other elements For example, Cu and Ni may be contained as optional elements for improving various properties or as impurities as long as their content does not exceed 0.1%. Other elements may also be contained as optional elements or as impurities as long as their content does not exceed 0.05%.

[0031] [Number density of precipitates in each portion of steel sheet] The electrical steel sheet according to this embodiment is manufactured on the premise that no hot-rolled sheet annealing is performed in the manufacturing process, and by actively controlling fine precipitates, the deviation in magnetic properties in the width direction, or in the width direction and length direction, of the steel sheet (including the coil state) is small.

[0032] In order to eliminate deviations in the magnetic properties of steel sheets in the longitudinal and transverse directions, it is necessary to control precipitates formed by impurities contained in the steel sheets. The presence of these precipitates affects recrystallization and grain growth in hot-rolled steel sheets and finished sheets, thereby significantly affecting the properties of the products.

[0033] Typically, hot-rolled sheet annealing is performed by continuous annealing, so the thermal history of the steel sheet does not change significantly between the center and both ends in the longitudinal direction, or between the center and both ends in the width direction. As a result, the deviation in the magnetic properties of the product sheet is small. On the other hand, if hot-rolled sheet annealing is not performed, the thermal history during hot rolling affects the steel sheet until just before finish annealing, which inevitably results in large deviations in the magnetic properties of the steel sheet in the longitudinal and width directions. In contrast, in the electrical steel sheet according to this embodiment, the number density of precipitates in the width direction is controlled, and preferably the number density of precipitates in the length direction is also controlled. As a result, even when hot-rolled sheet annealing is not performed, the deviation in the magnetic properties of the coil in the width and length directions is small. Specifically, this is controlled as follows.

[0034] (fW = DWmax / DWmin: 5.0 or less) In the electrical steel sheet according to this embodiment, in the TL portion, when the maximum value of the number density of precipitates having a particle size in the range of 0.05 to 0.50 μm at the center of the steel sheet in the thickness direction in the W / 10 portion, the W / 4 portion, and the W / 2 portion is DWmax and the minimum value is DWmin, fW, which is the ratio of DWmax to DWmin, expressed by the following formula (1), is 5.0 or less. An fW of 5.0 or less can reduce the deviation of the magnetic properties in the width direction of the steel sheet. This range of fW is the range derived from Experimental Example 1, which will be described later. fW = DWmax / DWmin Formula (1) Here, there is no significant difference in the temperature distribution that appears in the width direction of the steel sheet depending on the position in the longitudinal direction (the temperature distribution in the width direction observed in the TL portion shows a similar tendency at other positions, such as the L / 2 portion and the EL portion). Therefore, by evaluating the TL portion, it can be estimated that the ratio of the maximum to the minimum number density of precipitates also has a similar tendency in other portions. Therefore, in this embodiment, the evaluation is performed in the TL portion.

[0035] From the viewpoint of reducing the deviation of the magnetic properties in the width direction of the steel sheet, fW is preferably set to 4.0 or less, more preferably to 3.0 or less, and even more preferably to 2.0 or less.

[0036] DWmin and DWmax can be determined by the following method. At each of the W / 10, W / 4, and W / 2 positions in the TL portion of the steel sheet, a sample is taken. The central surface is exposed by polishing so that a surface parallel to the sheet surface can be observed at the center in the sheet thickness direction (from the surface to 1 / 4 to 3 / 4 of the sheet thickness in the sheet thickness direction). Then, etching is performed using a SPEED method (potential electrolysis using a non-aqueous electrolyte) or the like, and the precipitates on the observation surface are observed. Observation is performed using a scanning electron microscope (SEM) at a magnification of 5000x and an acceleration voltage of 15 kV in a 1 mm x 1 mm area. The precipitates observed here are limited to those with a particle size of 0.05 to 0.50 μm. Here, the particle size refers to the circle-equivalent diameter if the precipitate is approximately circular, the diagonal length if the precipitate is rectangular, and the average length of the major and minor axes if the precipitate is elliptical. This is because, assuming the chemical composition of the steel sheet according to this embodiment and the manufacturing method described below, the number of precipitates with a grain size of less than 0.05 μm or more than 0.50 μm is small and considered negligible. The number density of precipitates with a grain size of 0.05 to 0.50 μm at each position of the W / 10 part, W / 4 part, and W / 2 part is determined, and the number density at the position with the largest value is designated DWmax, and the number density at the position with the smallest value is designated DWmin. The observed precipitates are often one or more of AlN, MnS, TiN, and Ti(C,S). This is because, within the chemical composition range of the electrical steel sheet according to this embodiment, these precipitates are likely to have a grain size of 0.05 to 0.50 μm at the temperature during finish annealing, the final step in manufacturing a product sheet from hot rolling. The precipitates are identified by analyzing them with an energy dispersive X-ray analyzer (EDX) attached to a scanning electron microscope (SEM) at an acceleration voltage of 15 kV during the above observation.

[0037] (Variation of Magnetic Properties in the Width Direction) In the electrical steel sheet according to this embodiment, as described above, by controlling fW, the variation of the magnetic properties in the width direction is reduced. For example, based on Experimental Example 1 described later, the magnetic flux density B50 when excited in a magnetic field of 5000 A / m was measured at the W / 10, W / 4, and W / 2 parts of the TL portion, and the difference between the maximum and minimum values ​​was taken as ΔB50a (T). Furthermore, the iron loss W15 / 50 at 50 Hz at a magnetic flux density of 1.5 T was measured, and the difference between the maximum and minimum values ​​was taken as ΔW15 / 50a (W / kg). ΔB50a satisfies the following formula (3), and ΔW15 / 50a satisfies the following formula (4): ΔB50a (T)≦0.02... formula (3) ΔW15 / 50a (W / kg)≦0.4... formula (4)

[0038] ΔB50a is preferably 0.01 (T) or less. As ΔB50a approaches 0, a significant burden is placed on the manufacturing process, resulting in increased costs. Therefore, ΔB50a is preferably 0.005 (T) or more. Furthermore, ΔW15 / 50a is preferably 0.3 (W / kg) or less, more preferably 0.2 (W / kg) or less. As ΔW15 / 50a approaches 0, a significant burden is placed on the manufacturing process, resulting in increased costs. Therefore, ΔW15 / 50a is preferably 0.1 (W / kg) or more. For example, if the average grain size of the steel sheet before cold rolling is controlled to a high degree of uniformity, ΔB50a and ΔW15 / 50a may satisfy formulas (3) and (4) even if fW is not 5.0 or less. However, in the electrical steel sheet according to this embodiment, the deviation in magnetic properties is reduced by controlling the chemical composition and fW.

[0039] (Experimental Example 1) A slab containing, in mass%, 0.0012% C, 3.00% Si, 0.5% Al, 0.20% Mn, and 0.05% Sn as its chemical composition, with the balance being Fe and impurities, was heated to 1160 ° C. and then hot-rolled at a finish hot rolling temperature of 900 ° C. to obtain a hot-rolled steel sheet having a thickness of 2.0 mm, which was then coiled at 800 ° C. (coiling temperature). Then, annealing was performed at a soaking temperature of 750 ° C. and a soaking time of 2 hours, and air-cooled to room temperature. Then, cold-rolling was performed until the thickness became 0.5 mm. Then, finish annealing was performed at a soaking temperature of 1000 ° C. and a soaking time of 30 seconds. Samples of 55 mm in size were sheared in the length direction and width direction from each of the W / 10, W / 4, and W / 2 parts of the TL portion of the steel sheet after the finish annealing. The obtained samples were then measured for B50 (a measured value of magnetic flux density when excited in a magnetic field of 5000 A / m) and W15 / 50 (a measured value of iron loss at 50 Hz and a magnetic flux density of 1.5 T) using the SST method (Single Sheet Tester method) of JIS C 2556:2015. The difference between the maximum and minimum B50 values ​​at each of the W / 10, W / 4, and W / 2 positions was taken as the ΔB50a value, and the difference between the maximum and minimum W15 / 50 values ​​was taken as the ΔW15 / 50a value, which were used as indicators of deviation in magnetic properties in the width direction.

[0040] As shown in FIGS. 1 and 2, it is clear that by controlling fW to 5.0 or less, the deviation of the magnetic properties in the width direction of the steel sheet can be reduced.

[0041] Furthermore, it can be seen that by controlling the ratio fW of the number density shown in formula (1) to 5.0 or less, the deviation of the magnetic properties in the width direction can be reduced to a range in which ΔB50a and ΔW15 / 50a satisfy formulas (3) and (4): ΔB50a (T)≦0.02 ... formula (3) ΔW15 / 50a (W / kg)≦0.4 ... formula (4)

[0042] (fL = DLmax / DLmin: 5.0 or less) In the electrical steel sheet according to this embodiment, when the maximum number density of precipitates having a grain size in the range of 0.05 to 0.50 μm at the center in the sheet thickness direction of the W / 2 portion, the TL portion, the L / 2 portion, and the EL portion is DLmax and DLmin, respectively, the ratio of DLmax to DLmin, expressed by the following formula (2), fL, is preferably 5.0 or less. fL = DLmax / DLmin Equation (2) When fL is 5.0 or less, the deviation of magnetic properties in the length direction of the steel sheet can be reduced. When fW is 5.0 or less and fL is 5.0 or less, the deviation of magnetic properties in both the width direction and the length direction can be reduced. This range of fL is derived from Experimental Example 2, which will be described later.

[0043] From the viewpoint of reducing the deviation of the magnetic properties in the longitudinal direction of the steel sheet, fL is more preferably 4.0 or less, even more preferably 3.0 or less, and even more preferably 2.0 or less.

[0044] DLmin and DLmax can be determined from samples taken at the TL, L / 2, and EL positions of the W / 2 part of the steel plate in the same manner as DWmin and DWmax were determined.

[0045] (Variation in Magnetic Properties in the Lengthwise Direction) In the electrical steel sheet according to this embodiment, as described above, by controlling fL, the variation in magnetic properties in the lengthwise direction (longitudinal direction: usually the rolling direction) is reduced. For example, based on Experimental Example 2 described below, the magnetic flux density B50 when excited in a magnetic field of 5000 A / m is measured at the TL portion, L / 2 portion, and EL portion of the W / 2 portion of the steel sheet, and the difference between the maximum and minimum values ​​is defined as ΔB50b (T). Furthermore, the iron loss W15 / 50 at 50 Hz at a magnetic flux density of 1.5 T is measured and the difference between the maximum and minimum values ​​is defined as ΔW15 / 50b (W / kg). ΔB50b satisfies the following formula (5), and ΔW15 / 50b satisfies the following formula (6). ΔB50b(T)≦0.02...Equation (5) ΔW15 / 50b(W / kg)≦0.4...Equation (6)

[0046] ΔB50b is preferably 0.01 (T) or less. As ΔB50b approaches 0, a significant burden is placed on the manufacturing process, resulting in increased costs, so ΔB50b is preferably 0.005 (T) or more. Furthermore, ΔW15 / 50b is preferably 0.3 (W / kg) or less, more preferably 0.2 (W / kg) or less. As ΔW15 / 50b approaches 0, a significant burden is placed on the manufacturing process, resulting in increased costs, so ΔW15 / 50b is preferably 0.1 (W / kg) or more. ΔB50b is more preferably 0.02 (T) or less, and even more preferably 0.01 (T) or less. As ΔB50b approaches 0, a significant burden is placed on the manufacturing process, resulting in increased costs, so ΔB50b is preferably 0.005 (T) or more. ΔW15 / 50b is more preferably 0.3 (W / kg) or less, and even more preferably 0.2 (W / kg) or less. As ΔW15 / 50b approaches 0, the manufacturing process is significantly burdened, resulting in increased costs. Therefore, ΔW15 / 50b is preferably 0.05 (W / kg) or more. The rolling direction is obvious when the material is a coil or when the rolling direction is recorded. In the case of a full-width cut sheet sample, the rolling direction can be determined from the dimensions if the width is known. Furthermore, if at least one width edge remains, a person skilled in the art can easily determine the width direction and rolling direction from the condition of the end face (presence or absence of edge drop, presence or absence of plating). Alternatively, the Z-plane of the sheet (a plane parallel to both the longitudinal and width directions of the sheet) is polished from the surface to a depth of 1 / 4 of the sheet thickness, and then mirror-polished, and an Mn concentration map of a 500 μm × 500 μm area is obtained by EPMA, and if solidification segregation of Mn is measured in the form of streaks, the longitudinal direction of the streak pattern may be determined to be the rolling direction. Alternatively, if rolling marks are observed as lines extending in the rolling direction when the steel sheet surface is irradiated with light from a light source, the extending direction of the lines may be determined to be the rolling direction.

[0047] (Experimental Example 2) Test pieces were also taken from the same coil as in Experimental Example 1, and the deviation of the magnetic properties in the length direction (longitudinal direction) of the grain-oriented electrical steel sheet according to this embodiment was measured in the same manner as the magnetic measurement in the width direction in Experimental Example 1. That is, samples of 55 mm in size were sheared in the length direction and width direction at the center in the width direction (W / 2 part) of the TL portion, 1 / 2L portion, and EL portion, respectively. For these samples, B50 and W15 / 50 were measured using the SST method of JIS C 2556:2015, and the differences between the maximum and minimum values, ΔB50b and ΔW15 / 50b, were used as indicators of deviation of the magnetic properties. In the electrical steel sheet according to this embodiment, by controlling the fL in the TL portion, 1 / 2L portion, and EL portion to 5.0 or less, the deviation of the magnetic properties in the length direction of the steel sheet including the coil can be reduced, as shown in Figures 3 and 4.

[0048] Furthermore, by controlling the ratio fL of number density shown in formula (2) to 5.0 or less, it is possible to reduce the deviation of magnetic properties in the longitudinal direction of the steel sheet to a range where ΔB50b(T) satisfies formula (5) and ΔW15 / 50b(W / kg) satisfies formula (6): ΔB50b(T)≦0.02... formula (5) ΔW15 / 50b(W / kg)≦0.2... formula (6)

[0049] <Manufacturing Method> The electrical steel sheet according to this embodiment is not limited in its manufacturing method, and the effects thereof can be obtained as long as it has the above-mentioned characteristics. However, it can be manufactured by a manufacturing method including the following steps: (I) a hot rolling step of heating a slab and hot rolling it to obtain a hot-rolled steel sheet; (II) a coiling step of coiling the hot-rolled steel sheet after the hot rolling step at a coiling temperature; (III) a cold rolling step of cold-rolling the hot-rolled steel sheet after the coiling step to obtain a cold-rolled steel sheet; and (IV) a finish annealing step of annealing the cold-rolled steel sheet after the cold rolling step. Furthermore, the following steps may be further included, as necessary: ​​(V) an insulating coating forming step of forming an insulating coating on the surface of the cold-rolled steel sheet. Each step will be described below. Known conditions can be applied to conditions not described below.

[0050] (Hot Rolling Process) In the hot rolling process, the slab is heated and hot rolled to obtain a hot-rolled steel sheet. The slab heating temperature is preferably 1050 to 1250°C. If the temperature is less than 1050°C, the coil winding temperature cannot be raised above a certain temperature, resulting in deterioration of the product's magnetic properties. On the other hand, if the slab heating temperature exceeds 1250°C, precipitates are excessively dissolved, and fine precipitates are formed during hot rolling, resulting in deterioration of the product's iron loss. Of these, the preferred range is 1100 to 1200°C.

[0051] Before passing through the first stand in the finish rolling in the hot rolling process, it is preferable to use an edge heater to make the temperature of the outermost ends on both sides of the steel sheet in the width direction 10 to 100°C higher than that of the center (w / 2 part) (providing a temperature difference). Heating the edge portions, which are easily cooled by exposure to the outside air after coiling, before finish rolling makes it possible to suppress the temperature difference in the width direction after coiling. A temperature difference of less than 10°C does not provide sufficient effect. On the other hand, if the temperature difference exceeds 100°C, the structure of the steel sheet in the width direction at the end portions recrystallizes, causing embrittlement and making cold rolling difficult. The temperature difference may be 30°C or more, or may be 50°C or more. The temperature difference may also be 80°C or less. The temperature when passing through the final stand in the finish rolling in the hot rolling process is preferably in the range of 800 to 1000°C. This is because, outside this range, the range required for the hot-rolled coil coiling temperature cannot be ensured. A preferred temperature range when passing through the final stand is 900 to 1000°C. If the thickness of the hot-rolled steel sheet is too thick, the magnetic properties of the product sheet may deteriorate, and if it is too thin, there is a concern that the required temperature may not be ensured. Therefore, the thickness of the steel sheet (hot-rolled steel sheet) after the hot rolling process is preferably 1.6 to 2.8 mm. Of these, a more preferable thickness range is 1.8 to 2.5 mm. The chemical composition of the slab to be subjected to hot rolling may be the same as the chemical composition of the non-oriented electrical steel sheet to be finally obtained.

[0052] (Coiling Process) In the coiling process, the hot-rolled steel sheet after the hot rolling process is coiled at a coiling temperature. The coiling temperature is preferably in the range of 650 to 900°C. If the coiling temperature is less than 650°C, coiling becomes difficult and the magnetic properties become more variable. If the coiling temperature exceeds 900°C, the oxide layer on the surface becomes thick, which may cause deterioration of the appearance. The coiling temperature is preferably 700 to 850°C, and more preferably 700 to 800°C. The temperature at the widthwise center is set to 550°C or higher 10 minutes after coiling. If the temperature is less than 550°C after 10 minutes, the magnetic properties become more variable. The temperature at the widthwise center is preferably 600°C or higher or 650°C or higher 10 minutes after coiling. By increasing the steel sheet temperature after 10 minutes, the temperature deviation, particularly in the longitudinal direction, can be reduced, thereby reducing the deviation in the magnetic properties in the longitudinal direction. In normal coiling, it is not easy to raise the steel sheet temperature to 550°C or higher 10 minutes after coiling. Therefore, when the temperature is to be raised to 550°C or higher, it is desirable to take measures such as covering the coil with a coil cover.

[0053] By coiling the hot-rolled coil at a high temperature and then maintaining the temperature at 550°C or higher after 10 minutes, precipitates are intentionally precipitated in the hot-rolled coil, making it possible to reduce the variation in the number of precipitates in the width and length directions during the hot-rolling process. These precipitates hinder the movement of the domain walls of the electrical steel sheet, and are therefore thought to affect the magnetic flux density and iron loss. It is known that the number of precipitates mainly affects and deteriorates the magnetic flux density and iron loss. Generally, the number of precipitates depends on the cooling rate, and it is expected that the cooling rate after coiling the hot-rolled coil affects the number of precipitates. The average cooling rate from coiling to room temperature is not limited, but is preferably, for example, 20°C / second or less.

[0054] In the past, there was a difference in the cooling rate between the width and length of a coiled steel sheet after coiling. Specifically, the cooling rate was faster in the edge portion (end portion) including the W / 10 portion in the width direction, and in the top portion (end portion) including the TL portion and the bottom portion (end portion) including the EL portion (portion exposed to the outside air) in the length direction than in other portions. Furthermore, in the length direction, there were also portions other than the ends where the cooling rate locally varied. As a result, in the past, the amount of precipitates was smaller in the width and length directions, where the cooling rate was faster, than in other portions, and the difference in the number of precipitates depending on the portion in each of the width and length directions of the coil caused variations in magnetic flux density and iron loss.

[0055] In the manufacturing method of an electrical steel sheet according to this embodiment, in order to reduce the variation in the number of precipitates, the hot-rolled steel sheet is wound into a coil and the steel sheet temperature is maintained at 550°C or higher (preferably 600°C or higher, or 650°C or higher) 10 minutes after winding. This increases the amount of precipitates in the widthwise W / 10 portion (edge ​​portion) and the lengthwise TL and EL portions, which tend to have fewer precipitates, and reduces the difference in the number of precipitates between the widthwise and lengthwise directions of the hot-rolled coil. In the widthwise and lengthwise central portions, where precipitates are already abundant, the amount of precipitates is saturated immediately after coiling, and no significant change in the amount of precipitates occurs even if the temperature is maintained at 550°C or higher. The upper limit of the temperature 10 minutes after coiling is not limited, but is preferably 850°C or lower. Temperatures above 850°C may result in the formation of an internal oxide layer, which may deteriorate the appearance. By controlling PT2, which will be described later, in addition to the above control, fW and fL can be reduced. Furthermore, when fL is reduced, it is preferable to control PT1, which will be described later.

[0056] When the coiling temperature and the average temperature at the width direction center of each of the TL portion, L / 2 portion, and EL portion after 10 minutes (t1:h) are defined as T1 (°C), it is preferable to control PT1, which is expressed as (T1 + 273) × (20 + LOG(t1)), to 16,000 or more. This is because providing a sufficient amount of heat actively precipitates precipitates. In addition, the influence of the presence or absence of recrystallization on the magnetic properties of the hot-rolled steel sheet is extremely large. In order to precipitate precipitates at a temperature of 550°C or higher for 10 minutes and then uniformly recrystallize the structure of the hot-rolled steel sheet, it is necessary to hold the sheet at an appropriate temperature and time. To ensure recrystallization, when the soaking temperature after coiling is T2 (°C) and the soaking time is t2 (h), the parameter PT2, which is expressed as (T2 + 273) × (20 + LOG(t2)), is controlled to 16,000 or more. Here, the soaking time refers to the time during which the steel sheet temperature remains within a range of ±10°C of the target soaking temperature. The temperature of the inside of the coil, where direct measurement is not possible, is estimated from the temperature at a position where it can be measured and from the temperature record obtained in advance by attaching a thermocouple to the test coil.

[0057] (Cold Rolling Process) In the cold rolling process, the hot-rolled steel sheet after coiling is pickled under known conditions as necessary, and then cold-rolled. At this time, two cold rolling processes with annealing in between may be performed. The thickness of the steel sheet (cold-rolled steel sheet) after the cold rolling process is preferably 0.20 to 0.50 mm from the viewpoint of magnetic properties. Furthermore, in consideration of productivity, a range of 0.25 to 0.50 mm is more preferable. In this case, the final cold rolling ratio (cumulative reduction in the cold rolling process, or, if intermediate annealing is performed, cumulative reduction after intermediate annealing) is preferably 75 to 90% from the viewpoint of magnetic properties, and more preferably 80 to 88% from the viewpoint of magnetic properties and productivity.

[0058] (Finish annealing step) In the finish annealing step, the cold-rolled steel sheet after the cold rolling step is subjected to finish annealing. The finish annealing conditions are not particularly limited. From the viewpoint of magnetic properties, the soaking temperature during finish annealing is preferably 950 to 1100°C, more preferably in the range of 1000 to 1100°C. Regarding the annealing time, the soaking time is preferably 10 to 180 seconds, and more preferably 15 to 60 seconds, taking into consideration the magnetic properties and productivity.

[0059] (Insulating Coating Forming Step) In addition to the steps described above, the method for producing an electrical steel sheet according to this embodiment may include an insulating coating forming step of forming an insulating coating on the surface of the steel sheet after the finish annealing step, similar to the manufacturing steps of conventional non-oriented electrical steel sheets. The conditions for the insulating coating forming step may be the same as those for the insulating coating step of conventional non-oriented electrical steel sheets.

[0060] Next, examples of the present invention will be described, but the conditions in the examples are merely examples adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these examples. Various conditions can be adopted in the present invention as long as they do not deviate from the gist of the present invention and achieve the object of the present invention.

[0061] The slabs with the adjusted chemical compositions were cast, heated, and hot-rolled under the conditions shown in Table 2 to form hot-rolled steel sheets, which were then coiled. Then, the hot-rolled steel sheets were pickled and cold-rolled to obtain cold-rolled steel sheets with thicknesses of 0.20 to 0.50 mm.

[0062] The cold-rolled steel sheets were subjected to finish annealing under any of the conditions shown in Table 2 to obtain non-oriented electrical steel sheets. An insulating coating was formed on the surface of some of the steel sheets (C1 to C5, c18 to c27). The chemical composition of the steel sheets (base steel sheets) of the obtained non-oriented electrical steel sheets was measured and found to have the chemical components shown in Tables 1A and 1B, with the balance being Fe and impurities totaling 0.50% or less.

[0063] For non-oriented electrical steel sheets (C1 to C24, c1 to c28) shown in Tables 3A to 3D and 4A to 4D, which had any of the chemical compositions shown in Table 1A and Table 1B and were manufactured by any of the manufacturing methods shown in Table 2, the number densities of precipitates at the center in the sheet thickness direction in the W / 10 part, W / 4 part, and W / 2 part of the TL part, and in the TL part, L / 2 part, and EL part of the W / 2 part were measured using SEM and EDX under the conditions described above, and fW and fL were calculated. The results are shown in Tables 4A to 4D.

[0064] In addition, at the W / 10 part, W / 4 part, and W / 2 part of the TL part, and at the TL part, L / 2 part, and EL part of the W / 2 part, B50 (magnetic flux density when a magnetic field of 5000 A / m is applied) and W15 / 50 (iron loss at 50 Hz at a magnetic flux density of 1.5 T) were measured using the SST method (Single Sheet Tester method) of JIS C 2556:2015. From the obtained results, △B50a, △W15 / 50a, △B50b, and △W15 / 50b were calculated. The results are shown in Tables 4A to 4D.

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076] As can be seen from Tables 1A to 4D, in examples (invention examples) having a predetermined chemical composition and fW of 5.0 or less, the deviation in magnetic properties in the width direction was small even without hot-rolled sheet annealing, and the magnetic properties were also good, with iron loss at each position of W / 10 part, W / 4 part, W / 2 part, TL part, L / 2 part, and EL part being 4.0 W / kg or less. In contrast, in examples having a chemical composition outside the range of the present invention or unfavorable manufacturing conditions, fW exceeded 5.0 and the deviation in magnetic properties in the width direction was large.

[0077] According to the present invention, a non-oriented electrical steel sheet having small deviation in magnetic properties in the width direction and good magnetic properties can be obtained, and therefore has high industrial applicability.

Claims

1. A steel plate having a chemical composition, in mass%, of C: 0.0030% or less, Si: 1.40 to 3.50%, Al: 0.10 to 2.00%, Mn: 0.10 to 2.00%, P: 0.18% or less, S: 0.0030% or less, N: 0.0030% or less, Ti: 0.0030% or less, B: 0.0020% or less, Sn: 0 to 0.20%, Sb: 0 to 0.100%, and the balance: Fe and impurities; The width of the steel plate is W, a range of 1 / 20 to 3 / 20 of the plate width W from an end of the steel plate in the width direction toward the center in the width direction is defined as W / 10 part, a range of 4 / 20 to 6 / 20 of the plate width is defined as W / 4 part, and a range of 9 / 20 to 11 / 20 of the plate width is defined as W / 2 part, the length of the steel plate is L, a range from one end of the steel plate in the length direction to L / 10 is defined as TL part, a range from 2 / 5 to 3 / 5 of the length L from the end is defined as L / 2 part, and a range from 9L / 10 to the other end is defined as EL part, and in the TL part, among the number densities of precipitates having a particle size in the range of 0.05 to 0.50 μm at the center in the plate thickness direction of the steel plate in the W / 10 part, the W / 4 part, and the W / 2 part, the maximum value is defined as DWmax and the minimum value is defined as DWmin. A non-oriented electrical steel sheet, characterized in that fW, which is the ratio of DWmax to DWmin expressed by the following formula (1), is 5.0 or less: fW=DWmax / DWmin Formula (1) 2. The non-oriented electrical steel sheet according to claim 1, wherein, in the W / 2 portion, the TL portion, the L / 2 portion, and the EL portion, the maximum number density of precipitates having a grain size in the range of 0.05 to 0.50 μm at the center in the sheet thickness direction is represented by DLmax and the minimum number density is represented by DLmin, and the ratio fL of DLmax to DLmin, as expressed by the following formula (2), is 5.0 or less. fL=DLmax / DLmin Formula (2) 3. The non-oriented electrical steel sheet according to claim 1, wherein the magnetic flux density B50 is measured at the W / 10 part, the W / 4 part, and the W / 2 part of the TL portion of the steel sheet when excited in a magnetic field of 5000 A / m, and the difference between the maximum and minimum values ​​is ΔB50a, and the iron loss W15 / 50 is measured at 50 Hz at a magnetic flux density of 1.5 T, and the difference between the maximum and minimum values ​​is ΔW15 / 50a, the ΔB50a satisfies the following formula (3), and the ΔW15 / 50a satisfies the following formula (4): ΔB50a (T)≦0.02 ... formula (3) ΔW15 / 50a (W / kg)≦0.4 ... formula (4) 4. The non-oriented electrical steel sheet according to claim 2, wherein the magnetic flux density B50 is measured at the W / 10 part, the W / 4 part, and the W / 2 part of the TL portion of the steel sheet when excited in a magnetic field of 5000 A / m, the difference between the maximum and minimum values ​​is ΔB50a, and the iron loss W15 / 50 is measured at 50 Hz at a magnetic flux density of 1.5 T, the difference between the maximum and minimum values ​​is ΔW15 / 50a, where ΔB50a satisfies the following formula (3) and ΔW15 / 50a satisfies the following formula (4): ΔB50a (T)≦0.02 ... formula (3) ΔW15 / 50a (W / kg)≦0.4 ... formula (4) 5. The non-oriented electrical steel sheet according to claim 2, wherein ΔB50b, in T, represents the difference between the maximum and minimum values ​​of magnetic flux density B50 in the TL portion, the L / 2 portion, and the EL portion of the W / 2 portion of the steel sheet when excited in a magnetic field of 5000 A / m, and ΔW15 / 50b, in W / kg, represents the difference between the maximum and minimum values ​​of iron loss W15 / 50 at a magnetic flux density of 1.5 T and 50 Hz in the TL portion, the L / 2 portion, and the EL portion of the steel sheet, satisfies the following formula (5) and the ΔW15 / 50b value satisfies the following formula (6): ΔB50b≦0.02 ... formula (5) ΔW15 / 50b≦0.2 ... formula (6) 6. A non-oriented electrical steel sheet according to any one of claims 1 to 5, characterized in that the precipitates are one or more of AlN, MnS, TiN, and Ti(C,S).

7. A non-oriented electrical steel sheet according to any one of claims 1 to 5, characterized in that the chemical composition satisfies 0.02≦[Sn] + 2 × [Sb]≦0.20, where [Sn] is the Sn content in mass% and [Sb] is the Sb content in mass%.

8. The non-oriented electrical steel sheet according to claim 6, characterized in that, when the Sn content in mass % of the chemical composition is [Sn] and the Sb content in mass % is [Sb], the chemical composition satisfies 0.02≦[Sn] + 2 × [Sb]≦0.

20.

9. The non-oriented electrical steel sheet according to any one of claims 1 to 5, characterized in that the surface of the steel sheet has an insulating coating.

10. The non-oriented electrical steel sheet according to claim 6, characterized in that the surface of the steel sheet has an insulating coating.

11. The non-oriented electrical steel sheet according to claim 7, characterized in that the surface of the steel sheet has an insulating coating.

12. The non-oriented electrical steel sheet according to claim 8, characterized in that the surface of the steel sheet has an insulating coating.

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