JP7529973B2 - Non-oriented electrical steel sheet for rotors and its manufacturing method - Google Patents

Description

The present invention relates to non-oriented electrical steel sheets used as rotor core materials for rotating machines, and in particular to non-oriented electrical steel sheets that have excellent mechanical and magnetic properties and can withstand stress during high-speed rotation or repeated stress fluctuations during acceleration and deceleration.

In recent years, in the field of electrical equipment (especially rotating machines, small and medium-sized transformers, electrical equipment, etc., in which non-oriented electrical steel sheets are used as the iron core material), there has been a movement to conserve the global environment, represented by the worldwide saving of electricity and energy and the reduction of _CO2 emissions. In this context, the demand for high efficiency and miniaturization is becoming stronger. In this social environment, it is of course an urgent task to improve the performance of non-oriented electrical steel sheets. At the same time, coupled with the recent remarkable development of system control technology, in the rotating machine field, various rotating machine drive controls are becoming possible due to the sophistication of drive systems. That is, by controlling the frequency of the drive power supply, rotating machines that enable variable speed operation and high-speed operation at commercial frequencies or higher are increasing, and this is becoming a key technology in promoting the above-mentioned high efficiency and miniaturization.

To realize such a high-speed rotating machine, it is first necessary to make the rotor structure capable of withstanding the stresses that occur during high-speed rotation. In general, the centrifugal force acting on the rotor core of a rotating machine is proportional to the rotation radius and the square of the rotation speed. For this reason, the rotor of a large and/or high-speed rotating machine is subjected to very large stresses, and the rotor core material is required to have high strength. In addition, with the recent progress in IPM (Interier Permanent Magnet) rotors, there is a demand for rotor core materials with higher strength. In IPM rotors, in order to increase the effectively usable magnetic flux of the magnet, the bridge section provided on the outer periphery is narrowed, and a high-strength core material that can withstand the high stresses acting on the bridge section is required. In addition, in electromagnetic switches, electromagnetic switches, electromagnetic contactors, etc., the contacts are repeatedly brought into contact by electromagnetic force, so high strength of the contacts may be required.

Generally, laminated non-oriented electromagnetic steel sheets are often used for the rotor core of rotating machines, but in high-speed rotating machines such as those mentioned above, the required mechanical strength may not be satisfied, and in such cases, rotors made of solid cast steel have been used. However, since the rotor of a rotating machine utilizes magnetic phenomena, the core material must have excellent mechanical and magnetic properties. In other words, since solid cast iron rotors are one piece, the eddy current loss in the core is very large, and high-frequency iron loss increases significantly, especially at high speed rotation, and the efficiency of the rotating machine is significantly lower than that of rotors made of laminated electromagnetic steel sheets. Furthermore, if the magnetic flux density of the rotor core material is low, the excitation ampere turns must be large to pass the necessary magnetic flux to the rotor to generate the required torque, which leads to increased copper loss in the excitation coil.

As such, it is desirable for rotor core materials for high-speed rotating machines to have high mechanical strength and excellent magnetic properties, particularly in terms of high-frequency iron loss associated with high speed rotation. In the field of cold-rolled steel sheets, methods such as solid solution strengthening, precipitation strengthening, processing strengthening, grain refinement strengthening, and strengthening by transformation structure are generally used to increase the mechanical strength of steel sheets, but high mechanical strength and low iron loss are physically incompatible, and it has been extremely difficult to satisfy both simultaneously.

Several proposals have been made for non-oriented electrical steel sheets having high strength.
To improve strength by solid solution strengthening alone, it is necessary to increase the amount of alloy added; for example, as in Patent Documents 1 and 2, by increasing the Si content to 3.5-7.0%, a strength of 70 kg/mm2 or ^more can be obtained, but in addition to the embrittlement of the steel sheet causing problems in rollability, there are also problems in that the saturation magnetic flux density decreases and the magnetic flux density B50 is 1.56-1.62 T, which is lower than that of normal non-oriented electrical steel sheets. In Patent Document 2, the problem of brittle fracture of the steel sheet is solved by forming a thin ribbon through rapid solidification, but there is a problem that MnS and AlN precipitate finely, inhibiting domain wall movement and grain growth and deteriorating hysteresis loss.
In the case where strength is improved by using grain refinement strengthening in addition to solid solution strengthening, for example, Patent Document 3 proposes a high-strength non-oriented electrical steel sheet with a yield strength of 60 kgf/mm2 or higher, which is obtained by setting the Si content at 2.0 to ^3.5 %, increasing the Ni or Ni and Mn content, performing normal cold rolling, and controlling the annealing conditions. This technology allows the amount of alloying elements to be reduced compared to the case where strength is improved only by solid solution strengthening, and can avoid a decrease in rollability due to embrittlement of the steel sheet, but the improvement in magnetic flux density is insufficient.
In addition to solid solution strengthening and grain refinement strengthening, if precipitation strengthening is appropriately applied, the strength can be significantly improved compared to the case of solid solution strengthening alone and grain refinement strengthening. For example, Patent Document 4 proposes a high-strength non-oriented electrical steel sheet with a yield strength of ≧70 kgf/mm2 grade by setting the Si content at ^2.0-4.0 %, increasing the Ni or Ni and Mn content, and implementing precipitation strengthening with carbonitrides of Nb, Zr, Ti, and V, but the iron loss is significantly deteriorated. In addition, the precipitates become coarse due to high-temperature heat treatment, reducing the effect of improving the strength, so that hot-rolled sheet annealing cannot be performed, and it is difficult to form a texture that is favorable for the magnetic properties in the product, resulting in problems of deterioration of the magnetic flux density B50 and hysteresis loss.
On the other hand, a technology for improving the crystal orientation of a steel sheet, in other words, the texture, and increasing the magnetic flux density is disclosed in Patent Document 5. In this technology, it is shown that the crystal orientation can be concentrated in the {100} orientation by using (1) a strip casting method, (2) a thin slab continuous casting method, (3) a lubricated hot rolling method, (4) a high-temperature hot-rolled sheet annealing + cold rolling heavy reduction method, (5) a multiple cold rolling method, or the like, after the formation of fine sulfides is avoided by containing one or more elements selected from the group consisting of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd.

Japanese Unexamined Patent Publication No. 60-238421 Japanese Unexamined Patent Publication No. 61-9520 Japanese Patent Application Publication No. 62-256917 Japanese Unexamined Patent Publication No. 2-8346 JP 2019-183185 A

The inventors have studied the characteristics of the above core technologies and have tried to combine them appropriately to simultaneously realize the preferred characteristics of each technology. However, when solid solution strengthening, grain refinement effect, and precipitation strengthening are combined, the strength of the steel sheet basically follows the sum of these effects, but even when texture improvement technology is further combined with this, the concentration of {100} orientation hardly increases. Specifically, it has been found that in a steel sheet which contains large amounts of Si, Al, P, Mn, and Ni as solid solution strengthening elements, one or more selected from Nb, Zr, V, Ti, Mo, and W as precipitation strengthening elements, and appropriate amounts of C or N, and further contains one or more selected from the group consisting of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd, thereby avoiding the formation of fine sulfides, the accumulation of {100} orientation is hardly improved even if (1) a strip casting method, (2) a thin slab continuous casting method, (3) a lubricated hot rolling method, (4) a high-temperature hot rolled sheet annealing + cold rolling heavy reduction method, (5) a multiple cold rolling method, or the like is simply applied.
In view of the above, the present invention provides a non-oriented electrical steel sheet which is excellent in both mechanical properties and magnetic properties, and which has high strength, low high-frequency core loss, and high magnetic flux density.

In order to solve the above problems and simultaneously achieve high strength, low core loss, and high magnetic flux density, the present inventors have actively studied measures to improve texture, increase resistivity, and reduce sheet thickness by utilizing precipitates that are finely precipitated by finish annealing regardless of the thermal history of the previous process in addition to solid solution strengthening, and by rendering harmless sulfides that have a small effect on high strength but a large effect on magnetic properties. In particular, the inventors have studied the reason why (1) strip casting, (2) thin slab continuous casting, (3) lubricated hot rolling, (4) high-temperature hot rolled sheet annealing + cold rolling heavy reduction, and (5) multiple cold rolling, which have the effect of significantly increasing the accumulation of {100} orientation in steel sheets that do not contain a large amount of solid solution strengthening elements or precipitation strengthening elements, hardly work in steel sheets that contain a large amount of solid solution strengthening elements or precipitation strengthening elements. As a result, it was concluded that if some of the solid solution strengthening elements, particularly Ni or Mn, segregate in the steel before cold rolling, the effect of controlling the crystal orientation by the above (1) to (5) may be lost. Based on this assumption, a study was conducted on a process to avoid the segregation of Ni and Mn, particularly in hot-rolled sheets, and it was concluded that the concentration of the {100} orientation after cold rolling and annealing can be increased to the same level as that of steel sheets that do not contain large amounts of Ni and Mn by increasing the cooling rate in a specific temperature range after hot-rolling finish rolling.
Furthermore, the steel components, crystal structure, and crystal orientation that can achieve both the required high strength and good magnetic properties were quantitatively specified. Specifically, it was found that it is possible to achieve high strength, low high-frequency core loss, and high magnetic flux density by utilizing the addition of elements such as Ni and Mn based on the Si content within the range that can be passed through the manufacturing process of normal non-oriented electrical steel sheets, and further by setting the {100} plane intensity of the inverse pole figure of the product to 2.4 or more, the area ratio of crystal grains having a crystal orientation of {100} orientation (within a tolerance of 20°) to the entire field of view to 18% or more, and the average crystal grain size to 20 μm or less. Here, the tolerance of 20° or less means that the angle between the normal vector of the crystal plane of each crystal grain and the normal vector of the target crystal plane (in this case, the {100} plane) is within 20°. In addition, as manufacturing methods that can produce this steel plate, the inventors have revealed a method in which, in addition to any of (1) strip casting, (2) thin slab continuous casting, (3) lubricated hot rolling, (4) high-temperature hot-rolled sheet annealing + cold rolling heavy reduction, and (5) multiple cold rolling, the cooling rate from 900°C to 650°C in the thermal history before cold rolling of the material to be cold rolled is 20°C/sec or more.

The above problem can be solved by the following means:

[1]
C, by mass%, from 0% to 0.05%;
N: more than 0% to 0.01%,
Si: 2.50% to 4.50%,
sol. Al: 0.15% to 3.0%,
P: 0.005% to 0.200%,
S: 0.0100% or less,
Concerning Ni and Mn, at least one of Ni: 0.5% to 4.0% and Mn: 0.15% to 2.0% is contained;
The balance: Fe and impurities are included in the chemical composition, and the inverse pole figure {100} plane intensity is 2.4 or more.
The area ratio of crystal grains having a crystal orientation of {100} orientation (within a tolerance of 20°) relative to the entire field of view as measured by electron backscatter diffraction (EBSD) is 18% or more;
The average crystal grain size is 20 μm or less,
A non-oriented electrical steel sheet having a sheet thickness of 0.10 mm to 0.30 mm.
[2]
The non-oriented electrical steel sheet according to [1], wherein R represented by the following formula 1 is 54 or more when the Si content (mass%) is [Si], the Al content (mass%) is [Al], and the Mn content (mass%) is [Mn]:
R=9.9+12.4×[Si]+10.0×[Al]+6.6×[Mn] (Formula 1)
[3]
The non-oriented electrical steel sheet according to [1] or [2], wherein the area ratio of crystal grains having a crystal orientation of {411} orientation (within a tolerance of 20°) relative to the entire field of view as measured by electron backscatter diffraction (EBSD) is 70% or more.
[4]
The non-oriented electrical steel sheet according to any one of [1] to [3], wherein the area ratio of crystal grains having a crystal orientation of {111} orientation (within a tolerance of 20°) relative to a total field of view is 25% or less when measured by electron backscatter diffraction (EBSD).
[5]
In mass percent,
The non-oriented electrical steel sheet according to any one of [1] to [4], characterized in that it contains one or more elements selected from the group consisting of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0005% to 0.0200% in total.
[6]
In mass percent,
The non-oriented electrical steel sheet according to any one of [1] to [5], characterized in that one or more selected from Nb, Zr, V, Ti, Mo, and W are contained in an amount satisfying the following formula 2:
0.1<(Nb+Zr+2×V+2×Ti+Mo+0.5×W)/8(C+N)<2.0 (Equation 2)
[7]
The method for producing a non-oriented electrical steel sheet according to any one of [1] to [6], characterized in that in a production process for a non-oriented electrical steel sheet in which a predetermined sheet thickness is obtained by performing one or more cold rollings, the cooling rate from 900°C to 650°C in the thermal history before cold rolling of a material to be subjected to cold rolling is 20°C/sec or more.

The present invention provides a non-oriented electrical steel sheet that has high strength, low core loss, and high magnetic flux density.

An embodiment of the present invention will be described in detail below.

In this specification, the "%" designation for the content of each element in a chemical composition means "mass %."
A numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits.
When the numerical range described before and after "to" is followed by "greater than" or "less than," it means that the numerical range does not include the numerical value as the lower limit or upper limit.
The term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.
"Inverse pole figure {100} plane strength" may be simply referred to as "{100} plane strength".
The "area ratio of crystal grains having a crystal orientation of {100} orientation (within a tolerance of 20°) relative to the entire visual field,""area ratio of crystal grains having a crystal orientation of {411} orientation (within a tolerance of 20°) relative to the entire visual field," and "area ratio of crystal grains having a crystal orientation of {111} orientation (within a tolerance of 20°) relative to the entire visual field, as measured by electron backscatter diffraction (EBSD)," are also referred to simply as the "area ratio of {100} orientation grains," the "area ratio of {411} orientation grains," and the "area ratio of {111} orientation grains," respectively.

<Non-oriented electrical steel sheet>
The non-oriented electrical steel sheet according to the first embodiment has a predetermined chemical composition and satisfies the following properties (1), (2), (3), (4), and (5).

(1) The {100} plane intensity of the inverse pole figure is 2.4 or more.
(2) The area ratio of crystal grains having a crystal orientation of {100} orientation (within a tolerance of 20°) relative to the entire visual field as measured by electron backscatter diffraction (EBSD) is 18% or more.
(3) The average crystal grain size is 20 μm or less.
(4) The plate thickness is 0.10 mm to 0.30 mm.
(5) Regarding Ni and Mn, at least one of Ni: 0.5% to 4.0% and Mn: 0.15% to 2.0% is contained.

The non-oriented electrical steel sheet according to the first embodiment has the above-mentioned configuration, resulting in a non-oriented electrical steel sheet with high strength, low core loss, and high magnetic flux density.

The non-oriented electrical steel sheet according to the first embodiment (hereinafter, common matters will be referred to as "non-oriented electrical steel sheet according to this embodiment") will be described in detail below.

The chemical composition of the non-oriented electrical steel sheet according to the present embodiment will be described. Note that, regarding the composition of the steel sheet, "%" stands for "mass %".
The chemical composition of the non-oriented electrical steel sheet according to this embodiment may be measured by a general analysis method for steel. For example, the chemical composition of the non-oriented electrical steel sheet may be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Specifically, a 35 mm square test piece taken from the non-oriented electrical steel sheet is measured under conditions based on a calibration curve created in advance using a Shimadzu ICPS-8100 or the like (measuring device), to identify the chemical composition. C and S may be measured using a combustion-infrared absorption method, and N may be measured using an inert gas fusion-thermal conductivity method.

The chemical composition of non-oriented electrical steel sheet is:
C: more than 0% to 0.05%,
N: more than 0% to 0.01%,
Si: 2.50% to 4.50%,
sol. Al: 0.15% to 3.0%,
P: 0.005% to 0.200%,
S: 0.0100% or less,
Concerning Ni and Mn, at least one of Ni: 0.5% to 4.0% and Mn: 0.15% to 2.0% is contained;
The balance includes Fe and impurities.

The non-oriented electrical steel sheet may be a non-oriented electrical steel sheet having a chemical composition containing one or more elements selected from the group consisting of C, N, Si, sol. Al, Mn, Ni, P, S, and Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd (hereinafter, sometimes referred to as the "specific element group"), with the balance being Fe and impurities. The non-oriented electrical steel sheet may also contain one or more elements selected from Nb, Zr, V, Ti, Mo, and W.

[C: more than 0% to 0.05%, N: more than 0% to 0.01%]
C (carbon) and N (nitrogen) are elements necessary for the formation of carbonitrides. Carbonitrides have the effect of increasing the strength of steel through precipitation strengthening and grain refinement strengthening. However, If the C content exceeds 0.05% and N content exceeds 0.01%, the core loss characteristics will deteriorate significantly due to magnetic aging, etc. For this reason, the C and N contents should be 0.05% or less and 0.01% or less, respectively. .01% or less.
On the other hand, the lower limit of the C and N contents is preferably more than 0%, and from the viewpoint of refining costs, is more preferably 0.0005% or more.

[Si: 2.50% to 4.50%]
Silicon (Si) is an element that increases the resistivity of steel, reduces eddy current loss, and improves iron loss. In addition, silicon has a high solid solution hardening ability, which contributes to the high strength of non-oriented electrical steel sheets. It is also an effective element for strengthening. High strength is important from the viewpoint of suppressing deformation and fatigue fracture during high speed rotation of a motor. In order to fully exert this effect, 2.50% It is necessary to contain Si. Therefore, the Si content is set to 2.50%.
On the other hand, if the Si content exceeds 4.50%, the workability tends to deteriorate, so the Si content is set to 4.50% or less.
The Si content is preferably 2.80% to 3.90%, and more preferably 3.20% to 3.80%.

[Sol. Al: 0.15% to 3.00%]
When aluminum (Al) is dissolved in steel, it has the effect of increasing the strength of the steel through solid solution strengthening, and also reduces eddy current loss by increasing the resistivity of non-oriented electrical steel sheets, improving the high-frequency It is an element that improves iron loss. On the other hand, compared to Si, Al causes a large decrease in saturation magnetic flux density, a large decrease in magnetic permeability, and an increase in hysteresis loss. If it is less than 0.15%, it is not possible to sufficiently increase the specific resistance. On the other hand, since Al reduces the saturation magnetic flux density of the steel sheet, if it exceeds 3.00%, the saturation magnetic flux density drops significantly, and the magnetic flux density B50 Therefore, the Al content is set to 0.15% to 3.00%.
The lower limit of the Al content is preferably 0.30%, and more preferably 0.60% or more.
The upper limit of the Al content is preferably 1.80%, and more preferably 1.20% or less.

[P: 0.005% to 0.200%]
P (phosphorus) is an element that has a great effect of increasing the strength of steel, and in order to achieve this effect, it is necessary to include 0.005% or more of it. On the other hand, P recrystallizes from grain boundaries during annealing. It is an element that has the effect of suppressing the growth of {111} oriented grains, which are inferior in magnetic properties. In order to exert such an effect, it is necessary to contain P by 0.005% or more. Therefore, the P content is set to 0.005% or more.
On the other hand, if the P content exceeds 0.200%, the steel sheet becomes embrittled, so the P content is set to 0.200% or less.
The P content is preferably 0.02% or more and 0.15% or less, and more preferably 0.08% or more and 0.12% or less.

[S: 0.0100% or less]
S (sulfur) is an element that increases iron loss and deteriorates magnetic properties by forming fine sulfides such as MnS. In addition, fine sulfides such as MnS undergo recrystallization and crystallization during annealing, etc. Inhibits grain growth.
On the other hand, the lower limit of the S content is preferably more than 0%, and from the viewpoint of refining costs, is more preferably 0.0001% or more, further preferably 0.0005% or more, and further preferably 0.0010% or more. The upper limit of the S content is preferably 0.0080% or less, and more preferably 0.0060% or less.

[One or more selected from the group consisting of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: total 0.0005% to 0.0200%]
Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd have the effect of fixing S as sulfides or oxysulfides, preventing fine precipitation of MnS and the like, smoothing the movement of domain walls, and reducing iron loss. Therefore, it is preferable to contain one or more elements selected from these specific elements. To exert such effects, the total content of one or more elements selected from the specific element group is set to 0.0005% or more.
On the other hand, if the total content of at least one element selected from the specific element group exceeds 0.0200%, the sulfides or oxysulfides themselves become excessive, and iron loss deteriorates. Therefore, the total content of at least one element selected from the specific element group is preferably 0.0200% or less.
The total content of one or more elements selected from the specific element group is preferably 0.0010% or more and 0.0150% or less, and more preferably 0.0020% or more and 0.0100% or less.

[Ni: 0.5% to 4.0%, Mn: 0.15% to 2.0%]
In order to increase the strength, at least one of Ni and Mn is further added. Ni and Mn have the effect of increasing the strength of the steel by solid solution strengthening, and also increase the electrical resistance to reduce eddy current loss. In order to obtain these effects, it is necessary to add 0.5% or more of Ni and 0.15% or more of Mn. Even if the manufacturing method of the present invention described later is applied, it becomes impossible to increase the concentration of the {100} orientation to the level required by the present invention. Therefore, Ni content is set to 4.0% or less, and Mn content is set to 2.0% or less.

[Nb, Zr, V, Ti, Mo, W]
Nb, Zr, V, Ti, Mo, and W form finely precipitated carbonitrides, and have the effect of increasing the strength of steel through precipitation strengthening and grain refinement strengthening. In particular, Nb has the effect of increasing the strength of steel through carbonitriding. The precipitation strengthening effect of the alloy is large, and at the same time, it has the effect of suppressing the grain growth after cold rolling and finish annealing, and can also contribute to reducing high-frequency iron loss by controlling the grain size.

In order to obtain the above-mentioned effects, it is preferable to contain one or more elements selected from Nb, Zr, V, Ti, Mo, and W in a range in which the value of the following formula 2 exceeds 0.1. In order to obtain the above-mentioned effects, it is necessary to keep C and N to 0.05% or less and 0.01% or less, respectively, as described above. However, if the value of the following formula 2 is 0.1 or less, excessive C or N will remain, and the iron loss characteristics may be significantly deteriorated due to magnetic aging.
On the other hand, if its content is too high, it may increase the recrystallization temperature and even embrittle the steel sheet. Therefore, when added, its content should be set to a range such that the value of the following formula 2 is less than 2.0.
0.1<(Nb+Zr+2×V+2×Ti+Mo+0.5×W)/8(C+N)<2.0 (Equation 2)

[Remainder]
The balance of the non-oriented electrical steel sheet is Fe and impurities. Here, the impurities refer to components contained in the raw materials or components mixed in during the manufacturing process, but not intentionally contained in the steel sheet .

[(Formula 1) R = 9.9 + 12.4 × [Si] + 10.0 × [Al] + 6.6 × [Mn]: 54 or more]
When the content (mass%) of Si is [Si], the content (mass%) of Al is [Al], and the content (mass%) of Mn is [Mn], R represented by the following formula 1 is preferably 54 or more.
R=9.9+12.4×[Si]+10.0×[Al]+6.6×[Mn] (Formula 1)

Here, when the amounts of Si, Al and Mn are increased, the resistivity increases and the eddy current loss decreases as described above. On the other hand, since Si is more likely to embrittle the steel sheet than Al and Mn, it is better to increase the amounts of Al and Mn, which are relatively less likely to embrittle the steel sheet, to increase the resistivity.
Therefore, from the viewpoint of increasing the resistivity and further reducing iron loss, it is preferable to set the R value (= 9.9 + 12.4 × [Si] + 10.0 × [Al] + 6.6 × [Mn]) to 54 or more, and more preferably to 56 or more.
On the other hand, if the Si content, Al content and Mn content are excessively increased, the steel sheet tends to become brittle. Also, if the Si content, Al content and Mn content are excessively increased, the saturation magnetic flux density is significantly decreased, and the magnetic flux density B50 is significantly decreased. Therefore, the R value is preferably 85 or less, more preferably 80 or less.

(Metal structure of non-oriented electrical steel sheet, etc.)
Next, the metal structure of the non-oriented electrical steel sheet according to this embodiment will be described.

[{100} surface strength: 2.4 or more]
The {100} plane strength (the {100} plane strength of the inverse pole figure) is 2.4 or more.

Here, the crystal orientation near {100} is a texture that contributes to low iron loss and improved magnetic flux density. As described above, increasing the amount of Si, Al, and Mn reduces the saturation magnetic flux density, but increasing the {100} plane strength improves the magnetic flux density B ₅₀ (magnetic flux density generated in a steel sheet when the steel sheet is magnetized with an exciting magnetizing force of 5000 A/m) and also reduces the hysteresis loss that constitutes the iron loss. In order to achieve such low iron loss and high magnetic flux density, a {100} plane strength of 2.4 or more is required. Therefore, the {100} plane strength of the inverse pole figure is set to 2.4 or more.
The stronger the {100} plane strength, the better the magnetic properties, and there is no need to specify an upper limit.
From the viewpoint of reducing iron loss and increasing magnetic flux density, the {100} plane intensity of the inverse pole figure is preferably 3.5 or more, and more preferably 3.8 or more.

[Area ratio of {100} oriented grains: 18% or more]
The area ratio of {100} oriented grains (area ratio of crystal grains having a crystal orientation of {100} orientation (within a tolerance of 20°) relative to the entire field of view as measured by electron backscatter diffraction (EBSD)) is 18% or more.

Here, as in the above, the crystal orientation near {100} is a texture that contributes to low iron loss and high magnetic flux density. As mentioned above, increasing the amount of Si, Al, and Mn reduces the saturation magnetic flux density, but increasing the probability of the existence of the area ratio of {100} oriented grains improves the magnetic flux density _B50 and also reduces the hysteresis loss that constitutes the iron loss. In order to achieve such low iron loss and high magnetic flux density, the area ratio of {100} oriented grains needs to be 18%. Therefore, the area ratio of {100} oriented grains is set to 18% or more.
The {100} area ratio of a {100} single crystal is 100%, and the higher the {100} area ratio, the better the magnetic properties are, and there is no need to specify an upper limit.
From the viewpoint of reducing iron loss and increasing magnetic flux density, the area ratio of {100} oriented grains is preferably 20% or more, and more preferably 22% or more.

[Thickness]
The plate thickness is 0.10 mm to 0.30 mm. If the plate thickness is too thin, cold rolling becomes difficult and industrial production becomes impossible. On the other hand, if the plate thickness is too thick, eddy current loss increases and iron loss deteriorates. Therefore, the plate thickness is set to 0.10 mm to 0.30 mm. The plate thickness is preferably 0.20 mm to 0.27 mm.

[Average crystal grain size]
The average crystal grain size of the electrical steel sheet according to the first embodiment is 20 μm or less. When the crystal grains become coarse, the strength decreases. Therefore, the average crystal grain size is set to 20 μm or less. There is no need to particularly limit the lower limit of the average grain size, and a 100% unrecrystallized structure may be used. When no recrystallized grains are observed, the average crystal grain size specified in the present invention is 0 (zero) μm. However, if the crystal grains are excessively fined and the average crystal grain size is too small, the sheet shape of the product steel sheet may deteriorate depending on the steel components, hot rolling and cold rolling conditions, and there may be a concern that the shape accuracy during punching may decrease, so the average crystal grain size is preferably 10 μm or more. From the viewpoint of achieving both the manifestation of the effects of the invention, including the high strength of the steel sheet, and the high level of shape accuracy during punching, the average crystal grain size is preferably 13 μm to 17 μm.

[Area ratio of {411} oriented grains: 70% or more]
The area ratio of {411} oriented grains (the area ratio of crystal grains having a crystal orientation of {411} orientation (within a tolerance of 20°) relative to the entire field of view as measured by electron backscatter diffraction (EBSD)) is preferably 70% or more.
Furthermore, in order to improve the magnetic properties of the non-oriented electrical steel sheet and realize low core loss and high magnetic flux density, it is good to increase the probability of the existence of {411} oriented grains, which are advantageous in magnetic properties. Therefore, the area ratio of {411} oriented grains is preferably 70% or more, and more preferably 80% or more. Note that, although the higher the area ratio of {411} oriented grains, the better, from the viewpoint of manufacturing, the upper limit of the area ratio of {411} oriented grains is, for example, 95% or less.

[Area ratio of {111} oriented grains: 25% or less]
The area ratio of {111} oriented grains (the area ratio of crystal grains having a crystal orientation of {111}} orientation (within a tolerance of 20°) relative to the entire field of view as measured by electron backscatter diffraction (EBSD)) is preferably 25% or less.
Furthermore, in order to improve the magnetic properties of the non-oriented electrical steel sheet and realize low core loss and high magnetic flux density, it is good to reduce the probability of the existence of {111} oriented grains, which are inferior in magnetic properties. Therefore, the area ratio of {111} oriented grains is preferably 25% or less, more preferably 15% or less, and even more preferably 10% or less. It is most preferable that the area ratio of {111} oriented grains is 0%, but from the viewpoint of manufacturing, the lower limit of the area ratio of {111} oriented grains is, for example, 5% or more.

[Tensile strength]
The tensile strength of the electrical steel sheet according to the first embodiment is preferably 600 MPa or more. When the tensile strength is in the above range, the steel sheet is suitable as a non-oriented electrical steel sheet for rotors. The tensile strength is more preferably 600 MPa to 800 MPa, and further preferably 650 MPa to 800 MPa.
If the tensile strength is less than 600 MPa, the deformation of the rotor core cannot be sufficiently suppressed. However, if the tensile strength exceeds 850 MPa, punching becomes difficult, and it may become difficult to obtain shape precision. Therefore, the upper limit of the tensile strength is preferably 850 MPa or less.

[others]
The non-oriented electrical steel sheet according to this embodiment may have an insulating coating on one or both sides.
In order to improve the magnetic properties of non-oriented electrical steel sheets, it is important to reduce iron loss. Iron loss is composed of eddy current loss and hysteresis loss. By providing an insulating coating on the surface of a non-oriented electrical steel sheet, it is possible to suppress conduction between the non-oriented electrical steel sheets stacked as an iron core, thereby reducing the eddy current loss of the iron core, and it is possible to further improve the practical magnetic properties of the non-oriented electrical steel sheet.

Here, the insulating coating is not particularly limited as long as it is used as an insulating coating for non-oriented electrical steel sheets, and known insulating coatings can be used. Examples of such insulating coatings include composite insulating coatings that are mainly made of inorganic materials and further contain organic materials. Here, the composite insulating coating is an insulating coating that is mainly made of at least one of inorganic materials such as metal chromate salts, metal phosphate salts, colloidal silica, Zr compounds, and Ti compounds, and has fine organic resin particles dispersed therein. In particular, from the viewpoint of reducing the environmental load during manufacturing, which has become increasingly necessary in recent years, insulating coatings that use metal phosphate salts, Zr or Ti coupling agents, or carbonates or ammonium salts of these as starting materials are preferably used.

The amount of the insulating coating is not particularly limited, but is preferably about 0.1 g/ ^m2 or more and 2.0 g/ ^m2 or less per side, and more preferably 0.2 g/ ^m2 or more and 1.8 g/ ^m2 or less per side. By forming the insulating coating so as to achieve such an amount of coating, it is possible to maintain excellent uniformity. When the amount of the insulating coating is measured after the fact, various known measuring methods can be used.
The amount of the insulating coating can be calculated, for example, by immersing a non-oriented electrical steel sheet on which an insulating coating has been formed in a hot alkaline solution to remove only the insulating coating, and then calculating the mass difference before and after removal of the insulating coating.

Next, we will explain the various measurement methods.

[{100} plane strength]
The {100} plane intensity is measured as follows.
For example, the plane orientation can be determined by comparing the integrated intensity of diffraction from each crystal plane from a normal X-ray diffraction profile with the ideal intensity ratio for a randomly oriented material. Measurements can be performed using, for example, a Rigaku Corporation horizontal sample type high-power X-ray diffractometer RINT-TTR3 or a powder X-ray diffractometer RINT-2000, but the measurement results are essentially independent of the measuring device.

[Area ratio of each orientation grain]
The area ratio of each orientation grain ({100} orientation grain, {411} orientation grain, {111} orientation grain) is measured as follows.
Using OIM Analysis (TSL), the area ratio of each grain orientation of interest is extracted (with a tolerance of 20°) from the field of view observed by a scanning electron microscope under the following measurement conditions. The extracted area is divided by the area of the field of view to obtain a percentage. This percentage is the area ratio of each grain orientation.

The details of the measurement conditions for determining the area ratio of each orientation grain are as follows.
Measurement equipment: Scanning electron microscope with electron backscatter diffraction (SEM-EBSD) "SEM model number JSM-6400 (manufactured by JEOL) EBSD detector model number "HIKARI" (manufactured by TSL) was used"
Step interval: 2 μm
Measurement object: Center layer (1/2 of plate thickness) of Z surface of steel plate (cut surface of steel plate cut in plate thickness direction)
Measurement area: 8000 μm × 2400 μm area Grain boundary: Angle difference in crystal orientation is 15° or more (a continuous area with an angle difference of less than 15° is considered as one crystal grain)

[Average crystal grain size]
In the data for calculating the area ratio, the diameter of a circle that is equal to the area of each crystal grain is taken as the crystal grain size of each crystal grain. The arithmetic average of the crystal grain sizes of all crystal grains that are recognized as crystal grains in the measurement area (whose crystal orientation can be identified by the Kikuchi line pattern of EBSD) is taken as the average crystal grain size defined in the present invention. Note that an area in which the Kikuchi line pattern of EBSD is unclear and the crystal orientation cannot be identified is judged to be an unrecrystallized structure. When the crystal orientation cannot be identified in the entire measurement area, it is a completely unrecrystallized structure, and in this invention, the average crystal grain size in this case is judged to be 0 (zero) μm.

[Tensile strength]
The tensile strength is measured by a tensile test in accordance with JIS Z 2241 (2011).

Next, an example of a method for manufacturing a non-oriented electrical steel sheet according to this embodiment will be described.

Examples of methods for producing the non-oriented electrical steel sheet according to this embodiment include the following: (1) strip casting, (2) thin slab continuous casting, (3) lubricated hot rolling, (4) high-temperature hot-rolled sheet annealing + cold rolling heavy reduction, and (5) multiple cold rolling.
These methods (1) to (5) are known as methods for increasing the concentration of {100} orientation in products and can be appropriately applied within known ranges, but in the production of the steel sheet of the present invention containing a large amount of Ni or Mn, it is necessary to set the cooling rate from 900°C to 650°C to 20°C/sec or more in the cooling process of the heat treatment process immediately before the start of cold rolling. When the Ni content is less than 0.5% by mass and the Mn content is less than 0.15% by mass, the cooling rate is hardly affected, but when the Ni or Mn content increases, the {100} plane intensity of the inverse pole figure decreases as the cooling rate slows, and the area ratio of crystal grains having a crystal orientation of {100} orientation (within a tolerance of 20°) to the entire visual field when measured by electron backscatter diffraction (EBSD) decreases. Although the detailed mechanism is unclear, it is believed that Ni and Mn easily segregate in steel, and when the cooling rate is slow, the segregation inhibits {100} recrystallization after cold rolling and annealing. The cooling rate is preferably 30°C/sec or more, and more preferably 50°C/sec or more.

(1) Strip Casting Method The strip casting method produces non-oriented electrical steel sheets as follows.
First, in the steelmaking process, hot rolled coils having a thickness of 1 to 3 mm are directly produced by strip casting.
In strip casting, molten steel is rapidly cooled between a pair of water-cooled rolls to obtain a steel sheet with a thickness equivalent to that of a direct hot-rolled coil. By increasing the temperature difference between the molten steel and the outermost surface of the steel sheet in contact with the water-cooled rolls sufficiently, the crystal grains solidified on the surface grow vertically to the steel sheet, forming columnar crystals.
In steels with a BCC structure, columnar crystals grow so that the {100} plane is parallel to the steel sheet surface. The {100} plane strength increases, and the probability of the existence of {100} oriented grains increases. It is important to prevent the {100} plane from being changed as much as possible by transformation, processing, or recrystallization. Specifically, it is important to make the steel a ferrite single phase from immediately after solidification to room temperature by including ferrite-promoting elements Si and Al and limiting the contents of austenite-promoting elements Mn and Ni, without undergoing austenite phase formation at high temperatures.
Even if austenite-ferrite transformation occurs, some of the {100} planes are maintained, but by adjusting the contents of Si, Al, Mn and Ni within the above ranges, a component system in which austenite-ferrite transformation does not occur is obtained.

Next, the hot-rolled coil steel sheet obtained by strip casting is hot-rolled, and then the obtained hot-rolled sheet is annealed (hot-rolled sheet annealing).
It is also possible to skip the hot rolling and directly carry out the subsequent steps.
In addition, the post-process may be performed without performing hot-rolled sheet annealing. Here, when 30% or more strain is introduced into the steel sheet by hot rolling, recrystallization may occur from the strain-introduced portion and the crystal orientation may change if hot-rolled sheet annealing is performed at a temperature of 550°C or higher. Therefore, when 30% or more strain is introduced by hot rolling, hot-rolled sheet annealing is not performed or is performed at a temperature at which recrystallization does not occur.
In this case, the cooling rate during the cooling process of the hot-rolled sheet annealing when the hot-rolled sheet annealing is performed, or during the cooling process of the strip casting when the hot-rolled sheet annealing is not performed, is 20° C./sec or more. The cooling rate is preferably 30° C./sec or more, and more preferably 50° C./sec or more.

Next, the steel sheet is subjected to pickling before cold rolling.
Pickling is a process necessary to remove scale from the surface of the steel sheet. Pickling conditions are selected according to the conditions for scale removal. Note that instead of pickling, scale may be removed by using a grinder.

Next, the steel sheet is subjected to cold rolling.
Cold rolling is an essential process for obtaining a desired product thickness. However, if the reduction ratio of cold rolling is too large, the desired crystal orientation cannot be obtained in the product. Therefore, the reduction ratio of cold rolling is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less. There is no particular need to set a lower limit for the reduction ratio of cold rolling, but the lower limit is determined based on the thickness of the steel sheet before cold rolling and the desired product thickness. In addition, cold rolling is required even when the surface properties and flatness required for a laminated steel sheet are not obtained, so the minimum cold rolling for that purpose is required.
The cold rolling may be carried out in a reverse mill or in a tandem mill.

In place of cold rolling, warm rolling may be performed at a temperature equal to or higher than the ductile/brittle transition temperature of the material in order to avoid brittle fracture.

Next, the steel sheet is subjected to finish annealing.
The conditions for the final annealing must be determined so as to obtain a crystal grain size that provides the desired magnetic properties and strength, but the conditions may be within the range of the final annealing conditions for normal non-oriented electrical steel sheets.
The final annealing may be a continuous annealing or a batch annealing, but from the viewpoint of cost, it is preferable to carry out the final annealing by a continuous annealing.
In particular, in the strip casting method, the columnar crystals developed by casting are processed by hot rolling and cold rolling, and then the crystal grains having a crystal orientation of {100} orientation (within a tolerance of 20°) are recrystallized by finish annealing.

Through the above steps, (1) the strip casting method produces the desired non-oriented electrical steel sheet.

(2) Thin slab continuous casting method In the thin slab continuous casting method, non-oriented electrical steel sheets are produced as follows.
In the thin slab continuous casting method, slabs with a thickness of 30 to 60 mm are produced in the steelmaking process, and rough rolling in the hot rolling process is omitted. It is desirable to fully develop columnar crystals in the thin slab, with the {100} plane parallel to the steel plate surface, and to leave the {100}<011> orientation obtained by processing the columnar crystals in the hot rolling in the hot rolled sheet. For this purpose, it is desirable not to perform electromagnetic stirring in the continuous casting. It is also desirable to reduce fine inclusions in the molten steel, which promote solidification nucleation, as much as possible.
The thin slab is then heated in a reheating furnace and subsequently finish-rolled in a hot rolling process to obtain a hot-rolled coil having a thickness of about 2 mm.

Thereafter, the hot-rolled coil steel sheet is subjected to hot-rolled sheet annealing, pickling, cold rolling, and finish annealing in the same manner as in (1) strip casting method.
In this case, the cooling rate during the cooling process of the hot-rolled sheet annealing when the hot-rolled sheet annealing is performed, and during the cooling process after the hot-rolled sheet finish rolling when the hot-rolled sheet annealing is not performed, is 20°C/sec or more. The cooling rate is preferably 30°C/sec or more, and more preferably 50°C/sec or more.

Through the above steps, (2) the thin slab continuous casting method produces the desired non-oriented electrical steel sheet.

(3) Lubricated Hot Rolling Method In the lubricated hot rolling method, non-oriented electrical steel sheets are manufactured as follows.
First, a slab is produced in a steelmaking process. After the slab is heated in a reheating furnace, it is subjected to rough rolling and finish rolling in succession in a hot rolling process to obtain a hot rolled coil.
Here, hot rolling is usually performed without lubrication, but hot rolling is performed under appropriate lubrication conditions. When hot rolling is performed under appropriate lubrication conditions, the shear deformation introduced near the surface layer of the steel sheet is reduced. This allows a processed structure having an RD//<011> orientation called α-fiber, which is usually developed in the center of the steel sheet, to develop to the vicinity of the surface layer of the steel sheet. For example, as described in JP-A-10-36912, 0.5 to 20% of oil and fat is mixed into the hot rolling roll cooling water as a lubricant during hot rolling, and the average friction coefficient between the finishing hot rolling roll and the steel sheet is set to 0.25 or less, thereby allowing α-fiber to develop.

Thereafter, the hot-rolled coil steel sheet is subjected to hot-rolled sheet annealing, pickling, cold rolling, and finish annealing in the same manner as in the (1) strip casting method. When α-fiber is developed in the hot-rolled coil steel sheet to the vicinity of the steel sheet surface layer, {h11}<1/h12>, particularly {100}<012> to {411}<148>, are recrystallized in the subsequent hot-rolled sheet annealing. When this steel sheet is pickled, cold rolled, and finish annealed, {100}<012> to {411}<148> are recrystallized. This increases the {100} plane strength and increases the probability of the existence of {100} oriented grains.
In this case, the cooling rate during the cooling process of the hot-rolled sheet annealing when the hot-rolled sheet annealing is performed, and during the cooling process after the hot-rolled sheet finish rolling when the hot-rolled sheet annealing is not performed, is 20°C/sec or more. The cooling rate is preferably 30°C/sec or more, and more preferably 50°C/sec or more.

Through the above steps, the desired non-oriented electrical steel sheet is obtained using the lubricated hot rolling method (3).

(4) High-temperature hot-rolled sheet annealing + cold rolling heavy reduction method In the high-temperature hot-rolled sheet annealing + cold rolling heavy reduction method, a non-oriented electrical steel sheet is manufactured as follows.
First, a slab is produced in a steelmaking process. After the slab is heated in a reheating furnace, it is subjected to rough rolling and finish rolling in succession in a hot rolling process to obtain a hot rolled coil.
Next, the hot-rolled coil steel sheet is subjected to hot-rolled sheet annealing, which causes recrystallization and coarsens the crystal grains to grow to a grain size of 300 to 500 μm.
The hot-rolled sheet annealing may be continuous annealing or batch annealing. From the viewpoint of cost, the hot-rolled sheet annealing is preferably performed by continuous annealing. To perform continuous annealing, it is necessary to grow crystal grains at high temperature in a short time. Specifically, for example, annealing is performed at a maximum temperature of 1,000°C to 1,050°C and a soaking time of 30 minutes to 60 minutes. Here, the soaking time refers to the time during which the maximum temperature is maintained at -10°C.
In this case, the cooling rate from 900° C. to 650° C. during the cooling process of the hot-rolled sheet annealing is set to 20° C./sec or more, preferably 30° C./sec or more, and more preferably 50° C./sec or more.

Next, the steel sheet is subjected to pickling and then cold rolling.
Here, in the case of high-grade non-oriented electrical steel sheets with a high Si content, if the grain size is too large, the steel sheet becomes brittle, and there is a concern of brittle fracture during cold rolling. Therefore, the average grain size of the steel sheet before cold rolling is usually limited to 200 μm or less. On the other hand, in the present invention, the average grain size before cold rolling is set to 300 to 500 μm, and the subsequent cold rolling is performed at a reduction ratio of 80 to 95%.
In addition, instead of cold rolling, warm rolling may be performed at a temperature equal to or higher than the ductile/brittle transition temperature of the material in order to avoid brittle fracture.
Then, when the final annealing is performed, the ND//<100> recrystallized grains grow, which increases the {100} plane intensity and increases the probability of the existence of {100} oriented grains.

Pickling and finish annealing are carried out in the same manner as in 1) strip casting method.

After going through the above steps, the desired non-oriented electrical steel sheet is obtained using (4) high-temperature hot-rolled sheet annealing + cold rolling heavy reduction method.

(5) Multiple Cold Rolling Process In the multiple cold rolling process, a non-oriented electrical steel sheet is manufactured as follows.
First, slabs are produced in the steelmaking process. After heating the slabs in a reheating furnace, they are hot-rolled, annealed, and pickled.

Next, the pickled steel sheet is subjected to cold rolling.
Here, in the case of high-grade non-oriented electrical steel sheets, the desired product thickness is obtained by one cold rolling after usually performing hot rolling, hot-rolled sheet annealing, and pickling. When the product thickness becomes thinner, 0.3 mm or less, the cold rolling reduction becomes high, and an ND//<111> texture called gamma fiber, which is unfavorable for magnetic properties, develops.
For this reason, cold rolling is performed two or more times with one or more annealings in between, and the final cold rolling reduction is set to 55 to 75%, which makes it possible to suppress the development of gamma fiber and obtain the desired product characteristics.
Furthermore, it is preferable to perform cold rolling three or more times with two or more annealings in between, and set the reduction ratio of the final cold rolling and the penultimate cold rolling to 55 to 75%, which can further suppress the development of gamma fibers, develop the ND//<001> texture, and obtain the desired product characteristics.
The cold rolling may be carried out in a reverse mill or in a tandem mill.

In addition, instead of cold rolling, warm rolling may be performed at a temperature equal to or higher than the ductile/brittle transition temperature of the material in order to avoid brittle fracture.
At this time, when hot-rolled sheet annealing is performed, the cooling process of the hot-rolled sheet annealing, and when hot-rolled sheet annealing is not performed, the cooling process after hot-rolling finish rolling is performed at a cooling rate of 20 ° C. to 650 ° C./second or more. Furthermore, it is preferable that the cooling rate of the annealing performed between cold rolling is 20 ° C. to 650 ° C./second or more. In addition, when multiple annealing and cold rolling are repeated, it is preferable that the cooling rate of the annealing from 900 ° C. to 650 ° C. in the cooling process of all annealing is 20 ° C./second or more, but the cooling rate of the annealing from 900 ° C. to 650 ° C. in the cooling process for at least one of the multiple annealings may be 20 ° C./second or more. The cooling rate is preferably 30 ° C./second or more, more preferably 50 ° C./second or more.

Then, the cold-rolled coil steel sheet is subjected to finish annealing in the same manner as in (1) strip casting method.

After going through the above steps, the desired non-oriented electrical steel sheet is obtained using the (5) multiple cold rolling method.

Here, when the non-oriented electrical steel sheet according to the first embodiment is manufactured by the manufacturing method described above, such as (1) strip casting, (2) thin slab continuous casting, (3) lubricated hot rolling, (4) high-temperature hot-rolled sheet annealing + cold rolling heavy reduction, or (5) multiple cold rolling, and the high strength required for a non-oriented electrical steel sheet for a rotor core or the like is realized, the finish annealing is performed at a low temperature. Specifically, for example, the finish annealing is performed at a maximum temperature of 750°C to 850°C and a soaking time of 10 seconds to 60 seconds. Here, the soaking time refers to the time during which the maximum temperature is maintained at -10°C.
This low-temperature finish annealing suppresses the growth of crystal grains, making the average crystal grain size 20 μm or less, and thus a high-strength non-oriented electrical steel sheet can be obtained.

The present invention will be described in more detail below with reference to examples. However, these examples do not limit the present invention.

(Example 1: Sheet thickness 0.20 mm) High temperature hot rolled sheet annealing + cold rolling heavy reduction method Steels having the chemical compositions shown in Table 1 were melted and hot rolled to produce 1.7 mm thick hot rolled sheets. The hot rolled sheets were annealed at 1,050°C for 30 minutes, and then the surface scale was removed by pickling. Thereafter, the sheets were finished to a thickness of 0.20 mm by cold rolling, and finish annealed at 750°C for 15 seconds. Steel 1U1 was finish annealed at 600°C for 15 seconds. Steel 1C1, Steel 1D1, and Steel 1G1 were broken during cold rolling.
Through the above steps, a non-oriented electrical steel sheet was obtained.
In Table 1, "Total" indicates the total amount of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd.

The following measurements were carried out on each of the obtained non-oriented electrical steel sheets. The results are shown in Table 2.

- {100} plane strength, area ratio of each orientation grain, average crystal grain size, tensile strength -
According to the methods described above, the {100} plane strength, the area ratio of each orientation grain ({100} orientation grains, {411} orientation grains, {111} orientation grains), the average crystal grain size, and the tensile strength were measured.

- Iron loss and magnetic flux density -
Measurement samples were obtained by cutting the obtained non-oriented electrical steel sheets into pieces having a width of 55 mm and a length of 55 mm.
The iron loss W _15/50 , iron loss W _10/400 , and magnetic flux density B ₅₀ of the measurement sample were then measured. Each magnetic property was measured in the rolling direction (L direction) and the direction perpendicular to the rolling (C direction) using a single sheet magnetic tester, and evaluated as the average value.

As can be seen from the above results, Steel 1A1 and Steel 1B1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, a tensile strength of 600 MPa or more, and good iron losses W15/50, W10/400, and magnetic flux density B50 immediately after annealing. However, after being held at 200° C. for 96 hours, magnetic aging occurred and the magnetic properties deteriorated.
Steel 1C2, Steel 1D2, Steel 1E5, Steel 1F5, and Steel 1G2 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but a tensile strength of less than 600 MPa. In Steel 1C2, Steel 1D2, and Steel 1E5, the iron loss W10/400 was further deteriorated.
Steel 1H1, Steel 1I1, and Steel 1S1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but fine sulfides in the grains increased, and iron losses W15/50 and W10/400 deteriorated. Steel 1T1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but the value of R represented by formula 1 was less than 54, and iron loss W10/400 deteriorated.
Steels 1E1 and 1F1 had an average crystal grain size of 20 μm or less, but had a {100} plane intensity of less than 2.4, a {100} area ratio of less than 18%, and a deteriorated magnetic flux density B50 .
Steel 1E2, Steel 1E3, Steel 1E4, Steel 1F2, Steel 1F3, Steel 1F4, Steel 1I2, Steel 1J1, Steel 1K1, Steel 1L1, Steel 1M1, Steel 1M2, Steel 1N1, Steel 1O1, Steel 1P1, Steel 1Q1, Steel 1R1, Steel 1U1, and Steel 1V1 had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by formula 1 of 54 or more, and had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50. Note that Steel 1U1 had a non-recrystallized structure, but had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50.
Steel 1WA1, Steel 1WB1, Steel 1WC1, Steel 1WD1, Steel 1WE1, and Steel 1WF1 were made by adding relatively excessive amounts of Nb and the like so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by Formula 1 of 54 or more. However, fine carbonitrides in the grains were increased, and iron loss W15/50 and iron loss W10/400 were relatively deteriorated compared to those in which the amount of Nb and the like was added in a preferable range.
Steel 1WA5, Steel 1WB5, Steel 1WC5, Steel 1WD5, Steel 1WE5, and Steel 1WF5 were made by adding a relatively small amount of Nb and the like so as to form carbonitrides, and had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, an R value represented by Formula 1 of 54 or more, and good iron loss W15/50, iron loss W10/400, and magnetic flux density B50. However, since the amount of fine carbonitrides was reduced, the tensile strength was relatively reduced compared to those in which the amount of Nb and the like was added in a preferred range.
Steel 1WA2, Steel 1WA3, Steel 1WA4, Steel 1WB2, Steel 1WB3, Steel 1WB4, Steel 1WC2, Steel 1WC3, Steel 1WC4, Steel 1WD2, Steel 1WD3, Steel 1WD4, Steel 1WE2, Steel 1WE3, Steel 1WE4, Steel 1WF2, Steel 1WF3, and Steel 1WF4 were alloys having Nb and the like added within a preferred range so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average crystal grain size of 20 μm or less, and an R value represented by Formula 1 of 54 or more, and were relatively good in iron loss W15/50, iron loss W10/400, magnetic flux density B50, and tensile strength compared to alloys having Nb and the like added outside the preferred range.
Steel 1X1, Steel 1X2, Steel 1X3, and Steel 1X4 were made by annealing the same 1.7 mm thick hot-rolled sheet at 1,050 ° C for 30 minutes, and then cooling at 900-650 ° C at a cooling rate of 10-50 ° C / sec. The surface scale was then removed by pickling, finished to a thickness of 0.20 mm by cold rolling, and finish annealed at 750 ° C for 15 seconds. Steel 1X1, Steel 1X2, Steel 1X3, and Steel 1X4 had the same average grain size of about 15 μm, and the tensile strength was 700-710 MPa. The {100} plane strength and {100} orientation grain area ratio increased with increasing cooling rate, and the {111} orientation grain area ratio decreased. The iron loss 15/50 and W10/400 decreased with increasing cooling rate, and the magnetic flux density B50 increased. Compared with Steels 1X2 to 1X4, Steel 1X1 had a slow cooling rate of 10° C./sec, low {100} plane strength, low {100} orientation grain area ratio, and poor iron loss W15/50, iron loss W10/400, and magnetic flux density B50.

(Example 2: Sheet thickness 0.15 mm) Thin slab continuous casting method Steel having the chemical composition shown in Table 3 was melted, and a 60 mm thick slab was produced without performing rough hot rolling. The slab was heated to 1,200 ° C in a heating furnace, and then a 1.2 mm thick hot-rolled sheet was produced by hot rolling. The hot-rolled sheet was annealed at 1,000 ° C for 60 seconds, and then the surface scale was removed by pickling. Then, it was finished to a thickness of 0.15 mm by cold rolling, and finish annealed at 750 ° C for 15 seconds.
Through the above steps, a non-oriented electrical steel sheet was obtained.
In Table 3, "Total" indicates the total amount of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd.

The same measurements as in Example 1 were carried out on each of the obtained non-oriented electrical steel sheets. The results are shown in Table 4.

As can be seen from the above results, Steel 2A1 and Steel 2B1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, a tensile strength of 600 MPa or more, and good iron losses W15/50, W10/400, and magnetic flux density B50 immediately after annealing. However, after being held at 200° C. for 96 hours, magnetic aging occurred and the magnetic properties deteriorated.
Steel 2C2, Steel 2D2, Steel 2E5, Steel 2F5, and Steel 2G2 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but a tensile strength of less than 600 MPa. Steel 2C2, Steel 2D2, and Steel 2E5 also showed a deterioration in iron loss W10/400.
Steel 2H1, Steel 2I1, and Steel 2S1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but fine sulfides in the grains increased, and iron losses W15/50 and W10/400 deteriorated. Steel 2T1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but the value of R represented by formula 1 was less than 54, and iron loss W10/400 deteriorated.
Steels 2E1 and 2F1 had an average crystal grain size of 20 μm or less, but had a {100} plane intensity of less than 2.4, a {100} area ratio of less than 18%, and a deteriorated magnetic flux density B50 .
Steel 2E2, Steel 2E3, Steel 2E4, Steel 2F2, Steel 2F3, Steel 2F4, Steel 2I2, Steel 2J1, Steel 2K1, Steel 2L1, Steel 2M1, Steel 2M2, Steel 2N1, Steel 2O1, Steel 2P1, Steel 2Q1, Steel 2R1, Steel 2U1, and Steel 2V1 had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by formula 1 of 54 or more, and had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50. Note that Steel 2U1 had a non-recrystallized structure, but had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50.
Steel 2WA1, Steel 2WB1, Steel 2WC1, Steel 2WD1, Steel 2WE1, and Steel 2WF1 were made by adding relatively excessive amounts of Nb and the like so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by Formula 1 of 54 or more. However, the amount of fine carbonitrides in the grains was increased, and iron loss W15/50 and iron loss W10/400 were relatively deteriorated compared to those in which the amount of Nb and the like was added in a preferable range.
Steel 2WA5, Steel 2WB5, Steel 2WC5, Steel 2WD5, Steel 2WE5, and Steel 2WF5 were made by adding a relatively small amount of Nb etc. so as to form carbonitrides, and had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, an R value represented by Formula 1 of 54 or more, and good iron loss W15/50, iron loss W10/400, and magnetic flux density B50. However, since the amount of fine carbonitrides was reduced, the tensile strength was relatively reduced compared to those in which the amount of Nb etc. added was within the preferred range.
Steel 2WA2, Steel 2WA3, Steel 2WA4, Steel 2WB2, Steel 2WB3, Steel 2WB4, Steel 2WC2, Steel 2WC3, Steel 2WC4, Steel 2WD2, Steel 2WD3, Steel 2WD4, Steel 2WE2, Steel 2WE3, Steel 2WE4, Steel 2WF2, Steel 2WF3, and Steel 2WF4 were alloys having Nb and the like added within a preferred range so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average crystal grain size of 20 μm or less, and R value represented by Formula 1 of 54 or more, and were relatively good in iron loss W15/50, iron loss W10/400, magnetic flux density B50, and tensile strength compared to alloys having Nb and the like added outside the preferred range.
Steel 2X1, Steel 2X2, Steel 2X3, and Steel 2X4 were made by annealing the same 1.2 mm thick hot-rolled sheet at 1,000 ° C for 60 seconds, and then cooling at 900-650 ° C at a cooling rate of 10-50 ° C / sec. The surface scale was then removed by pickling, finished to a thickness of 0.15 mm by cold rolling, and finish annealed at 750 ° C for 15 seconds. Steel 2X1, Steel 2X2, Steel 2X3, and Steel 2X4 had the same average grain size of about 15 μm, and the tensile strength was 690-705 MPa. The {100} plane strength and {100} orientation grain area ratio increased with increasing cooling rate, and the {111} orientation grain area ratio decreased. The iron loss 15/50 and W10/400 decreased with increasing cooling rate, and the magnetic flux density B50 increased. Compared with Steels 2X2 to 2X4, Steel 2X1 had a slow cooling rate of 10° C./sec, low {100} plane strength, low {100} orientation grain area ratio, and poor iron loss W15/50, iron loss W10/400, and magnetic flux density B50.

(Example 3: Plate thickness 0.25 mm) Strip casting method Molten steel having the chemical composition shown in Table 5 was rapidly cooled between a pair of water-cooled rolls to produce a 1.25 mm thick cast piece. The cast piece was pickled to remove surface scale, then finished to a thickness of 0.25 mm by cold rolling, and finish annealed at 750° C. for 15 seconds.
Through the above steps, a non-oriented electrical steel sheet was obtained.
In Table 5, "Total" indicates the total amount of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd.

The same measurements as in Example 1 were carried out on each of the obtained non-oriented electrical steel sheets. The results are shown in Table 6.

As can be seen from the above results, Steel 3A1 and Steel 3B1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, a tensile strength of 600 MPa or more, and good iron losses W15/50, W10/400, and magnetic flux density B50 immediately after annealing. However, after being held at 200° C. for 96 hours, magnetic aging occurred and the magnetic properties deteriorated.
Steel 3C2, Steel 3D2, Steel 3E5, Steel 3F5, and Steel 3G2 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but a tensile strength of less than 600 MPa. Steel 3C2, Steel 3D2, and Steel 3E5 also showed a deterioration in iron loss W10/400.
Steel 3H1, Steel 3I1, and Steel 3S1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but fine sulfides in the grains increased, and iron losses W15/50 and W10/400 deteriorated. Steel 3T1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but the value of R represented by formula 1 was less than 54, and iron loss W10/400 deteriorated.
Steels 3E1 and 3F1 had an average crystal grain size of 20 μm or less, but had a {100} plane intensity of less than 2.4, a {100} area ratio of less than 18%, and a deteriorated magnetic flux density B50 .
Steel 3E2, Steel 3E3, Steel 3E4, Steel 3F2, Steel 3F3, Steel 3F4, Steel 3I2, Steel 3J1, Steel 3K1, Steel 3L1, Steel 3M1, Steel 3M2, Steel 3N1, Steel 3O1, Steel 3P1, Steel 3Q1, Steel 3R1, Steel 3U1, and Steel 3V1 had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by formula 1 of 54 or more, and had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50. Note that Steel 3U1 had a non-recrystallized structure, but had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50.
Steel 3WA1, Steel 3WB1, Steel 3WC1, Steel 3WD1, Steel 3WE1, and Steel 3WF1 were made by adding relatively excessive amounts of Nb and the like so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by Formula 1 of 54 or more. However, the amount of fine carbonitrides in the grains was increased, and iron loss W15/50 and iron loss W10/400 were relatively deteriorated compared to those in which the amount of Nb and the like was added in a preferable range.
Steel 3WA5, Steel 3WB5, Steel 3WC5, Steel 3WD5, Steel 3WE5, and Steel 3WF5 were made by adding a relatively small amount of Nb etc. so as to form carbonitrides, and had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, an R value represented by Formula 1 of 54 or more, and good iron loss W15/50, iron loss W10/400, and magnetic flux density B50. However, since the amount of fine carbonitrides was reduced, the tensile strength was relatively reduced compared to those in which the amount of Nb etc. added was within the preferred range.
Steel 3WA2, Steel 3WA3, Steel 3WA4, Steel 3WB2, Steel 3WB3, Steel 3WB4, Steel 3WC2, Steel 3WC3, Steel 3WC4, Steel 3WD2, Steel 3WD3, Steel 3WD4, Steel 3WE2, Steel 3WE3, Steel 3WE4, Steel 3WF2, Steel 3WF3, and Steel 3WF4 were alloys having Nb and the like added within a preferred range so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average crystal grain size of 20 μm or less, and an R value represented by Formula 1 of 54 or more, and were relatively good in iron loss W15/50, iron loss W10/400, magnetic flux density B50, and tensile strength compared to alloys having Nb and the like added outside the preferred range.
Steel 3X1, Steel 3X2, Steel 3X3, and Steel 3X4 were rapidly cooled between a pair of water-cooled rolls to produce a 1.25 mm thick cast piece, and cooled at a cooling rate of 900-650 ° C., changed to 10-50 ° C./sec. Thereafter, the surface scale was removed by pickling, the piece was finished to a thickness of 0.25 mm by cold rolling, and finished annealed at 750 ° C. for 15 seconds. Steel 3X1, Steel 3X2, Steel 3X3, and Steel 3X4 had the same average grain size of about 15 μm, and the tensile strength was 690-705 MPa. The {100} plane strength and {100} orientation grain area ratio increased with increasing cooling rate, and the {111} orientation grain area ratio decreased. The iron loss 15/50 and W10/400 decreased with increasing cooling rate, and the magnetic flux density B50 increased. Compared with Steels 3X2 to 3X4, Steel 3X1 had a slow cooling rate of 10° C./sec, low {100} plane strength, low {100} orientation grain area ratio, and poor iron loss W15/50, iron loss W10/400, and magnetic flux density B50.

(Example 4) Lubricated hot rolling method Steels having the chemical compositions shown in Table 7 were melted and hot rolled to produce hot-rolled sheets having a thickness of 2.0 mm. In the hot rolling, cooling water containing 10% lubricating oil was sprayed onto the rolls to perform lubricated hot rolling. The hot-rolled sheets were annealed at 1,000°C for 60 seconds, and then the surface scale was removed by pickling. Thereafter, the sheets were finished to a thickness of 0.25 mm by cold rolling, and finish annealed at 750°C for 15 seconds.
Through the above steps, a non-oriented electrical steel sheet was obtained.
In Table 7, "Total" indicates the total amount of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd.

The same measurements as in Example 1 were carried out on each of the obtained non-oriented electrical steel sheets. The results are shown in Table 8.

As can be seen from the above results, Steel 4A1 and Steel 4B1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, a tensile strength of 600 MPa or more, and good iron losses W15/50, W10/400, and magnetic flux density B50 immediately after annealing. However, after being held at 200° C. for 96 hours, magnetic aging occurred and the magnetic properties deteriorated.
Steel 4C2, Steel 4D2, Steel 4E5, Steel 4F5, and Steel 4G2 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but a tensile strength of less than 600 MPa. In Steel 4C2, Steel 4D2, and Steel 4E5, the iron loss W10/400 was further deteriorated.
Steel 4H1, Steel 4I1, and Steel 4S1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but fine sulfides in the grains increased, and iron losses W15/50 and W10/400 deteriorated. Steel 4T1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but the value of R represented by formula 1 was less than 54, and iron loss W10/400 deteriorated.
Steels 4E1 and 4F1 had an average crystal grain size of 20 μm or less, but had a {100} plane intensity of less than 2.4, a {100} area ratio of less than 18%, and a deteriorated magnetic flux density B50 .
Steel 4E2, Steel 4E3, Steel 4E4, Steel 4F2, Steel 4F3, Steel 4F4, Steel 4I2, Steel 4J1, Steel 4K1, Steel 4L1, Steel 4M1, Steel 4M2, Steel 4N1, Steel 4O1, Steel 4P1, Steel 4Q1, Steel 4R1, Steel 4U1, and Steel 4V1 had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by formula 1 of 54 or more, and had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50. Note that Steel 4U1 had a non-recrystallized structure, but had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50.
Steel 4WA1, Steel 4WB1, Steel 4WC1, Steel 4WD1, Steel 4WE1, and Steel 4WF1 were made by adding relatively excessive amounts of Nb etc. so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by Formula 1 of 54 or more. However, fine carbonitrides in the grains were increased, and iron loss W15/50 and iron loss W10/400 were relatively deteriorated compared to those in which the amount of Nb etc. added was within the preferred range.
Steel 4WA5, Steel 4WB5, Steel 4WC5, Steel 4WD5, Steel 4WE5, and Steel 4WF5 were made by adding a relatively small amount of Nb etc. so as to form carbonitrides, and had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, an R value represented by Formula 1 of 54 or more, and good iron loss W15/50, iron loss W10/400, and magnetic flux density B50. However, since the amount of fine carbonitrides was reduced, the tensile strength was relatively reduced compared to those in which the amount of Nb etc. added was within the preferred range.
Steel 4WA2, Steel 4WA3, Steel 4WA4, Steel 4WB2, Steel 4WB3, Steel 4WB4, Steel 4WC2, Steel 4WC3, Steel 4WC4, Steel 4WD2, Steel 4WD3, Steel 4WD4, Steel 4WE2, Steel 4WE3, Steel 4WE4, Steel 4WF2, Steel 4WF3, and Steel 4WF4 were alloys having Nb and the like added within a preferred range so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by Formula 1 of 54 or more, and were relatively good in iron loss W15/50, iron loss W10/400, magnetic flux density B50, and tensile strength compared to alloys having Nb and the like added outside the preferred range.
Steel 4X1, Steel 4X2, Steel 4X3, and Steel 4X4 were made by annealing the same 2.0 mm thick hot-rolled sheet at 1,000 ° C for 60 seconds, and cooling it at 900-650 ° C at a cooling rate of 10-50 ° C / sec. Thereafter, the surface scale was removed by pickling, and the sheet was finished to a thickness of 0.25 mm by cold rolling, and then finished annealed at 750 ° C for 15 seconds. Steel 4X1, Steel 4X2, Steel 4X3, and Steel 4X4 had the same average grain size of about 15 μm, and the tensile strength was 695-710 MPa. The {100} plane strength and {100} orientation grain area ratio increased with increasing cooling rate, and the {111} orientation grain area ratio decreased. The iron loss 15/50 and W10/400 decreased with increasing cooling rate, and the magnetic flux density B50 increased. Compared with Steels 4X2 to 4X4, Steel 4X1 had a slow cooling rate of 10° C./sec, low {100} plane strength, low {100} orientation grain area ratio, and poor iron loss W15/50, iron loss W10/400, and magnetic flux density B50.

(Example 5) Multiple cold rolling method Steels having the chemical compositions shown in Table 9 were melted and hot-rolled to a thickness of 3.5 mm. The hot-rolled sheets were annealed at 1,000 ° C for 60 seconds, and then the surface scale was removed by pickling. Steels 5A1 to 5X4 were cold-rolled to a thickness of 0.50 mm, annealed at 1,000 ° C for 15 seconds, cold-rolled again to a thickness of 0.15 mm, and finish-annealed at 750 ° C for 15 seconds. Steel 5Y1 was cold-rolled to a thickness of 1.6 mm, annealed at 1,000 ° C for 60 seconds, cold-rolled to a thickness of 0.50 mm, annealed at 1,000 ° C for 15 seconds, cold-rolled again to a thickness of 0.15 mm, and finish-annealed at 750 ° C for 15 seconds.
Through the above steps, a non-oriented electrical steel sheet was obtained.
In Table 9, "Total" indicates the total amount of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd.

The same measurements as in Example 1 were carried out on each of the obtained non-oriented electrical steel sheets. The results are shown in Table 10.

As can be seen from the above results, Steel 5A1 and Steel 5B1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, a tensile strength of 600 MPa or more, and good iron losses W15/50, W10/400, and magnetic flux density B50 immediately after annealing. However, after being held at 200° C. for 96 hours, magnetic aging occurred and the magnetic properties deteriorated.
Steel 5C2, Steel 5D2, Steel 5E5, Steel 5F5, and Steel 5G2 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but a tensile strength of less than 600 MPa. Steel 5C2, Steel 5D2, and Steel 5E5 also showed a deterioration in iron loss W10/400.
Steel 5H1, Steel 5I1, and Steel 5S1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but fine sulfides in the grains increased, and iron losses W15/50 and W10/400 deteriorated. Steel 5T1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, and an average grain size of 20 μm or less, but the value of R represented by formula 1 was less than 54, and iron loss W10/400 deteriorated.
Steels 5E1 and 5F1 had an average crystal grain size of 20 μm or less, but had a {100} plane intensity of less than 2.4, a {100} area ratio of less than 18%, and a deteriorated magnetic flux density B50 .
Steel 5E2, Steel 5E3, Steel 5E4, Steel 5F2, Steel 5F3, Steel 5F4, Steel 5I2, Steel 5J1, Steel 5K1, Steel 5L1, Steel 5M1, Steel 5M2, Steel 5N1, Steel 5O1, Steel 5P1, Steel 5Q1, Steel 5R1, Steel 5U1, and Steel 5V1 had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by formula 1 of 54 or more, and had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50. Note that Steel 5U1 had a non-recrystallized structure, but had good tensile strength, iron loss W15/50, iron loss W10/400, and magnetic flux density B50.
Steel 5WA1, Steel 5WB1, Steel 5WC1, Steel 5WD1, Steel 5WE1, and Steel 5WF1 were made by adding relatively excessive amounts of Nb etc. so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by Formula 1 of 54 or more. However, fine carbonitrides in the grains were increased, and iron loss W15/50 and iron loss W10/400 were relatively deteriorated compared to those in which the amount of Nb etc. added was within the preferred range.
Steel 5WA5, Steel 5WB5, Steel 5WC5, Steel 5WD5, Steel 5WE5, and Steel 5WF5 were made by adding a relatively small amount of Nb etc. so as to form carbonitrides, and had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average crystal grain size of 20 μm or less, an R value represented by Formula 1 of 54 or more, and good iron loss W15/50, iron loss W10/400, and magnetic flux density B50. However, since the amount of fine carbonitrides was reduced, the tensile strength was relatively reduced compared to those in which the amount of Nb etc. added was within the preferred range.
Steel 5WA2, Steel 5WA3, Steel 5WA4, Steel 5WB2, Steel 5WB3, Steel 5WB4, Steel 5WC2, Steel 5WC3, Steel 5WC4, Steel 5WD2, Steel 5WD3, Steel 5WD4, Steel 5WE2, Steel 5WE3, Steel 5WE4, Steel 5WF2, Steel 5WF3, and Steel 5WF4 were alloys having Nb and the like added within a preferred range so as to form carbonitrides, and had {100} plane strength of 2.4 or more, {100} area ratio of 18% or more, average grain size of 20 μm or less, and R value represented by Formula 1 of 54 or more, and were relatively good in iron loss W15/50, iron loss W10/400, magnetic flux density B50, and tensile strength compared to alloys having Nb and the like added outside the preferred range.
Steel 5X1, Steel 5X2, Steel 5X3, and Steel 5X4 were prepared by annealing the same 3.5 mm thick hot-rolled sheet at 1,000 ° C for 60 seconds, cold rolling to 0.50 mm thick, annealing at 1,000 ° C for 15 seconds, and cooling at 900 to 650 ° C by changing the cooling rate from 10 to 50 ° C / sec. Thereafter, the surface scale was removed by pickling, cold rolling to a thickness of 0.15 mm, and finish annealing at 750 ° C for 15 seconds. Steel 5X1, Steel 5X2, Steel 5X3, and Steel 5X4 had the same average crystal grain size of about 15 μm, and the tensile strength was 695 to 705 MPa. The {100} plane strength and {100} orientation grain area ratio increased with increasing cooling rate, and the {111} orientation grain area ratio decreased. The iron loss W15/50 and W10/400 decreased with increasing cooling rate, and the magnetic flux density B50 increased. Compared with Steels 5X2 to 5X4, Steel 5X1 had a slow cooling rate of 10°C/sec, low {100} plane strength and low {100} orientation grain area ratio, and was inferior in iron loss W15/50, iron loss W10/400, and magnetic flux density B50.
Steel 5Y1 was prepared by annealing a 3.5 mm-thick hot-rolled sheet at 1,000° C. for 60 seconds, cold rolling to a thickness of 1.6 mm, annealing at 1,000° C. for 60 seconds, cold rolling to a thickness of 0.50 mm, annealing at 1,000° C. for 15 seconds, cold rolling again to a thickness of 0.15 mm, and finish annealing at 750° C. for 15 seconds. Steel 5Y1 had a {100} plane strength of 2.4 or more, a {100} area ratio of 18% or more, an average grain size of 20 μm or less, an R value represented by formula 1 of 54 or more, and good iron loss W15/50, iron loss W10/400, magnetic flux density B50, and tensile strength.

Claims (7)

C, by mass%, from 0% to 0.05%;
N: more than 0% to 0.01%,
Si: 2.50% to 4.50%,
sol. Al: 0.15% to 3.0%,
P: 0.005% to 0.200%,
S: 0.0100% or less ,
Ni : 0.5% to 4.0% (excluding 0.5% to 1.0%), and
Mn: 0.15% to 2.0 % ;
The balance is a chemical composition consisting of Fe and impurities, and the inverse pole figure {100} plane intensity is 3.5 or more,
The area ratio of crystal grains having a crystal orientation of {100} orientation (within a tolerance of 20°) relative to the entire field of view as measured by electron backscatter diffraction (EBSD) is 18% or more;
The average crystal grain size is 20 μm or less,
A non-oriented electrical steel sheet having a sheet thickness of 0.10 mm to 0.30 mm. 2. The non-oriented electrical steel sheet according to claim 1, wherein R represented by the following formula 1 is 54 or more, where R is the Si content (mass%), [Si], the Al content (mass%), and [Al], and the Mn content (mass%) is [Mn]:
R=9.9+12.4×[Si]+10.0×[Al]+6.6×[Mn] (Formula 1) A non-oriented electrical steel sheet according to claim 1 or 2, in which the area ratio of crystal grains having a crystal orientation of {411} (within a tolerance of 20°) relative to the entire field of view as measured by electron backscatter diffraction (EBSD) is 70% or more. A non-oriented electrical steel sheet according to any one of claims 1 to 3, in which the area ratio of crystal grains having a crystal orientation of {111} (within a tolerance of 20°) relative to the entire field of view as measured by electron backscatter diffraction (EBSD) is 25% or less. In mass percent,
The non-oriented electrical steel sheet according to any one of claims 1 to 4, characterized in that it contains one or more elements selected from the group consisting of Ca, Mg, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd in a total amount of 0.0005% to 0.0200%. In mass percent,
The non-oriented electrical steel sheet according to any one of claims 1 to 5, characterized in that one or more selected from Nb, Zr, V, Ti, Mo and W are contained in an amount within a range that satisfies the following formula 2:
0.1<(Nb+Zr+2×V+2×Ti+Mo+0.5×W)/8(C+N)<2.0 (Equation 2) A method for producing non-oriented electrical steel sheet according to any one of claims 1 to 6, characterized in that in the manufacturing process for non-oriented electrical steel sheet in which a predetermined sheet thickness is obtained by performing one or more cold rolling processes, the cooling rate from 900°C to 650°C in the thermal history before cold rolling of the material to be subjected to cold rolling is 20°C/sec or more.