Non-oriented electrical steel sheet

Abstract

Provided is a non-oriented electrical steel sheet which contains predetermined elements in mass%, has a metallographic structure having a transformation temperature Ar3 (DEG C) of 750-1050 DEG C and a recrystallization rate of 1-99%, has a sheet thickness of 0.50 mm or less, and in which, in an arbitrary cross-section, the area ratio of {411} crystal grains is Sac, the area ratio of {110} crystal grains is Sag, and the area ratio of {411} crystal grains in a region from the higher KAM value to 20% is Sbc, Sbc represents the area ratio of Sbc to Sbc represents the area ratio of Sbc to Sbc represents the area ratio of Sbc to Sbc. Sac > 0.120, Sac > Sbc > Sag, and 0.050 > Sag are satisfied.

Description

Technical Field

[0001] The present disclosure relates to a non-oriented electrical steel sheet. Background Art

[0002] Non-oriented electromagnetic steel sheets are used, for example, in the iron core of a motor. Non-oriented electromagnetic steel sheets are required to have excellent magnetic properties, such as low iron loss and high magnetic flux density, in the average of all directions parallel to the sheet surface (hereinafter sometimes referred to as "the average over the entire circumference within the sheet surface (average in all directions)"). Various technologies have been proposed in the past, but it is difficult to obtain sufficient magnetic properties in all directions within the sheet surface. For example, sometimes even if sufficient magnetic properties are obtained only in a specific direction within the sheet surface, sufficient magnetic properties cannot be obtained in other directions. Even if sufficient magnetic properties cannot be obtained only in a specific direction as one aspect, if high magnetic properties can be ensured in the rolling direction and in a continuous area such as the rolling direction to the left and right at 45°, it can be expected that the applicable motor shapes will increase and the versatility will also be improved.

[0003] In order to improve the magnetic properties, it is known that the development of the {100} crystal orientation or the reduction of the {111} crystal orientation is effective. In order to carry out such crystal orientation control, various component systems that cause γ→α phase transformation have been studied, as shown in Patent Documents 1 to 6. Among these technologies, refining the hot-rolled structure is a point. The steel composition with a low γ→α phase transformation temperature is set, and the γ phase is hot-rolled in the low-temperature γ region to accumulate a large amount of strain, thereby causing it to transform and achieve a fine-grained α phase structure at the time of hot rolling. In order to achieve this, based on the viewpoint of lowering the phase transformation temperature and delaying recovery recrystallization to promote strain accumulation, the addition of γ-stabilizing elements such as Mn, Cu, and Ni is flexibly utilized.

[0004] However, Mn is known as a segregation element. When its content increases, Mn segregates to the center of the hot-rolled sheet thickness, causing fracture during cold rolling of the hot-rolled sheet.

[0005] Furthermore, since the {100}<011> orientation is predominant in the technology utilizing the γ→α phase transition, the in-plane anisotropy is large, requiring different crystal orientation control than before.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 4029430

[0009] Patent Document 2: Japanese Patent No. 6319465

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2017-193731

[0011] Patent Document 4: WO2021 / 095846

[0012] Patent Document 5: Japanese Patent Application Laid-Open No. 2021-080501

[0013] Patent Document 6: Japanese Patent Application Laid-Open No. 2020-100860 Summary of the Invention

[0014] Technical problem to be solved by the invention

[0015] In view of the aforementioned problems, the object of the present disclosure is to provide a non-oriented electrical steel sheet in which Mn is suppressed so as not to cause problems with rollability and which has a chemical composition in which the contents of elements such as Mn, Cu and Ni are appropriate, thereby being able to obtain small in-plane anisotropy and excellent magnetic properties in the direction 45° from the rolling direction.

[0016] Technical means for solving technical problems

[0017] (1) A non-oriented electrical steel sheet according to one embodiment of the present disclosure has the following chemical composition:

[0018] By mass, contains

[0019] C: 0.0100% or less,

[0020] Si: 1.50% to 4.00%,

[0021] sol.Al: 0.0001%~1.0%,

[0022] S: 0.0100% or less,

[0023] N: 0.0100% or less,

[0024] Mn: 0.10% or more,

[0025] One or more selected from Mn, Ni, and Cu: less than 2.50% in total,

[0026] Mo: 0.00% to less than 2.50%,

[0027] Cr: 0.00% to less than 2.50%,

[0028] Ti: 0.000% to 0.005%,

[0029] Nb: 0.000% to 0.005%,

[0030] Sn: 0.000% to 0.400%,

[0031] Sb: 0.000% to 0.400%,

[0032] P: 0.000%~0.400%, and

[0033] One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0.0100% in total,

[0034] When the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is [P], the phase transition temperature Ar3 (°C) determined by the following formula (1) is 750 to 1050°C, and the remainder is composed of Fe and impurities.

[0035] Moreover, the plate thickness is less than 0.50 mm.

[0036] In any cross section, the area ratio of {411} grains is defined as Sac, the area ratio of {110} grains is defined as Sag, and the area ratio of {411} grains in the region from the side with the highest KAM (Kernel Average Misorientation) value to 20% is defined as Sbc. If Sac>0.120, Sac>Sbc>Sag, and 0.050>Sag are satisfied,

[0037] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])···(1).

[0038] (2) The non-oriented electrical steel sheet according to one embodiment of the present disclosure has the following chemical composition:

[0039] By mass, contains

[0040] C: 0.0100% or less,

[0041] Si: 1.50% to 4.00%,

[0042] sol.Al: 0.0001%~1.0%,

[0043] S: 0.0100% or less,

[0044] N: 0.0100% or less,

[0045] Mn: 0.10% or more,

[0046] One or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu: less than 2.50% in total,

[0047] Mo: 0.00% to less than 2.50%,

[0048] Cr: 0.00% to less than 2.50%,

[0049] Ti: 0.000% to 0.005%,

[0050] Nb: 0.000% to 0.005%,

[0051] Sn: 0.000% to 0.400%,

[0052] Sb: 0.000% to 0.400%,

[0053] P: 0.000%~0.400%, and

[0054] One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0.0100% in total,

[0055] When the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is [P], the phase transition temperature Ar3 (°C) determined by the following formula (1) is 750 to 1050°C, and the remainder is composed of Fe and impurities.

[0056] Moreover, the plate thickness is less than 0.50 mm.

[0057] In any cross section, the area ratio of {411} grains is defined as Sac, the area ratio of {110} grains is defined as Sag, and the area ratio of {411} grains in the region from the side with the highest KAM (Kernel Average Misorientation) value to 20% is defined as Sbc. If Sac>0.120, Sac>Sbc>Sag, and 0.050>Sag are satisfied,

[0058] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])···(1).

[0059] (3) In the non-oriented electrical steel sheet described in (1) or (2), it may be:

[0060] Magnetic flux density B in rolling direction 50 The magnetic flux density B is 1.58T or more and is 45° to the rolling direction. 50 More than 1.70T.

[0061] Effects of the Invention

[0062] According to the above aspect of the present disclosure, a non-oriented electrical steel sheet can be provided in which excellent magnetic properties can be obtained in the direction 45° from the rolling direction in a steel sheet in which Mn is suppressed so as not to cause problems with rollability and the chemical composition is set to an appropriate content of elements such as Mn, Cu and Ni. DETAILED DESCRIPTION

[0063] The inventors of the present invention conducted intensive research to address the aforementioned technical issues. As a result, they discovered that, by optimizing hot rolling conditions and forming an appropriate α-grained structure during the hot-rolled sheet stage, while ensuring rollability and further adjusting the composition, {411} crystal orientations developed during subsequent cold rolling and intermediate annealing. This {411} crystal orientation was further enriched by skin-pass rolling of the intermediate-annealed sheet and subsequent strain-induced grain boundary migration (SIBM) during final annealing. Furthermore, it was demonstrated that enriching the {411} crystal orientation effectively reduced in-plane anisotropy of magnetic properties and improved properties in the direction 45° from the rolling direction.

[0064] Based on this understanding, the inventors of the present invention conducted further in-depth studies and ultimately arrived at the present disclosure.

[0065] Below, the embodiments of the present disclosure are described in detail. It should be noted that in this specification, the numerical range represented by "to" represents a range that includes the numerical values recorded before and after "to" as the lower limit and upper limit. In addition, the various elements of the following embodiments can of course be combined individually.

[0066] In addition, in the embodiments of the present disclosure, the so-called "non-oriented electromagnetic steel sheet" includes not only steel sheets in coil form or cut sheet form, but also steel sheets processed into specific shapes as raw materials for products (components) such as motor cores, and steel sheets that are stacked after processing to form motor cores.

[0067] First, the chemical composition of the non-oriented electrical steel sheet and the steel material used in the method for producing the same according to the embodiments of the present disclosure will be described. In the following description, "%" in units of the content of each element contained in the non-oriented electrical steel sheet or steel material represents "mass %" unless otherwise specified. Furthermore, the chemical composition of the non-oriented electrical steel sheet represents the content based on 100% of the base material (excluding coatings, etc.).

[0068] In addition, in the numerical ranges described in stages in this specification, the upper limit value of a numerical range in a certain stage may be replaced by the upper limit value of a numerical range described in another stage, or may be replaced by a value shown in the Examples.

[0069] In the numerical ranges described in stages in this specification, the lower limit value of a certain numerical range may be replaced by the lower limit value of another numerical range described in stages, or may be replaced by a value shown in the Examples.

[0070] The non-oriented electrical steel sheet of the present embodiment has a chemical composition capable of causing ferrite-austenite transformation (hereinafter, α-γ transformation).

[0071] By mass, contains

[0072] C: 0.0100% or less,

[0073] Si: 1.50% to 4.00%,

[0074] sol.Al: 0.0001%~1.0%,

[0075] S: 0.0100% or less,

[0076] N: 0.0100% or less,

[0077] Mn: 0.10% or more,

[0078] One or more selected from Mn, Ni, and Cu: less than 2.50% in total,

[0079] Mo: 0.0%~less than 2.5%

[0080] Cr: 0.0% to less than 2.5%

[0081] Ti: 0.000%~0.005%

[0082] Nb: 0.000%~0.005%

[0083] Sn: 0.000% to 0.400%,

[0084] Sb: 0.000% to 0.400%,

[0085] P: 0.000%~0.400%, and

[0086] One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: the total is 0.0000% to 0.0100%, and the contents of C, Si, P, sol.Al, Mn, Mo, Cu, Cr and Ni meet the predetermined conditions described below, and the remainder is composed of Fe and impurities.

[0087] In the non-oriented electrical steel sheet of the present embodiment, it is preferred that the total content of one or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu is less than 2.50%.

[0088] Examples of impurities include impurities contained in raw materials such as ore and scrap, and impurities contained in the production process.

[0089] (C: 0.0100% or less)

[0090] C increases iron loss or causes magnetic aging. Therefore, the lower the C content, the better. This phenomenon is significant when the C content exceeds 0.0100%. Therefore, the C content is set to 0.0100% or less. Reducing the C content also helps to uniformly improve the magnetic properties in all directions within the plate surface. In addition, the lower limit of the C content is not particularly limited, but it is preferably set to 0.0005% or more based on the cost of decarburization treatment during refining.

[0091] (Si: 1.50% to 4.00%)

[0092] Si increases electrical resistance, reduces eddy current loss, lowers iron loss, or increases yield ratio, improving blanking workability into the iron core. When the Si content is less than 1.50%, these effects cannot be fully achieved. Therefore, the Si content is set to 1.50% or more. In addition, the Si content is preferably higher than 1.80, more preferably higher than 2.00. On the other hand, when the Si content is higher than 4.00%, the magnetic flux density decreases, or the hardness increases excessively, resulting in a decrease in blanking workability, or difficulty in cold rolling. Therefore, the Si content is set to 4.00% or less.

[0093] (sol.Al: 0.0001% to 1.0%)

[0094] Sol.Al increases resistance, reduces eddy current loss, and reduces iron loss. Sol.Al also helps to increase magnetic flux density B 50The relative magnitude relative to the saturation magnetic flux density. When the sol.Al content is less than 0.0001%, its effects cannot be fully achieved. Furthermore, Al also promotes desulfurization during steelmaking. Therefore, the sol.Al content is set to 0.0001% or higher. On the other hand, when the sol.Al content exceeds 1.0%, the magnetic flux density decreases, the yield ratio decreases, and blanking workability is reduced. Therefore, the sol.Al content is set to 1.0% or lower.

[0095] Here, the total content of Si and sol.Al is preferably higher than 1.80, more preferably higher than 2.00.

[0096] In addition, the so-called sol.Al refers to acid-soluble Al that is not converted into oxides such as Al2O3 but is soluble in acid.

[0097] Here, the so-called magnetic flux density B 50 , refers to the magnetic flux density in a magnetic field of 5000A / m.

[0098] (S: 0.0100% or less)

[0099] S is not an essential element and is contained in steel as an impurity, for example. S hinders recrystallization and grain growth during annealing through the precipitation of fine MnS. Therefore, the lower the S content, the better. The increase in iron loss and the decrease in magnetic flux density caused by such obstruction of recrystallization and grain growth are significant when the S content is higher than 0.0100%. Therefore, the S content is set to 0.0100% or less. In addition, the lower limit of the S content is not particularly limited, but is preferably set to 0.0003% or more based on the cost of desulfurization treatment during refining.

[0100] (N: 0.0100% or less)

[0101] Like C, N deteriorates magnetic properties, so the lower the N content, the better. Therefore, the N content is set to 0.0100% or less. The lower limit of the N content is not particularly limited, but is preferably set to 0.0010% or more based on the cost of denitrification treatment during refining.

[0102] (One or more selected from Mn, Ni, and Cu: less than 2.50% in total)

[0103] When the total amount of Mn, Ni, and Cu is 2.5% or more, the anisotropy of the magnetic properties increases, so the total amount of Mn, Ni, and Cu is set to less than 2.5%. Although the reason for the increase in anisotropy is unclear, it is believed that it is because it affects the slip deformation in the ferrite domain, promoting the formation and recrystallization of the {100} orientation. In addition, based on this viewpoint, the increase in the content of alloying elements is preferably set to 2.3% or less. The lower limit of the total amount of Mn, Ni, and Cu is not particularly limited, for example, it can be set to 0.10% or more, or it can be set to 0.50% or more, or 1.00% or more, and further 2.00% or more.

[0104] (One or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu: less than 2.50% in total)

[0105] In addition to the above-mentioned Mn, Ni, and Cu, Co, Pt, Pb, and Au also increase the anisotropy of magnetic properties. In this embodiment, it is preferred that the total content of these elements remain at less than 2.50%. In addition, since these elements will reduce the magnetic flux density, it is preferred to set the total content to less than 2.00%. The lower limit of the sum of Mn, Ni, Co, Pt, Pb, Au, and Cu is not particularly limited. For example, it can be set to more than 0.10%, or it can be set to more than 0.50%, or more than 1.00%, or further more than 2.00%. In particular, Co, Pt, Pb, and Au should be avoided from being actively added due to the high alloy cost. In addition, even considering the control of the Ar3 phase transition point, which is one of the characteristics of this embodiment, it is preferred to control the Ar3 phase transition point by containing Mn, Ni, and Cu. Therefore, the sum of Co, Pt, Pb, and Au is less than 0.5%, more preferably less than 0.1%, and further stays within the range of inevitable elements, and does not need to be actively added (it can also be set to 0%).

[0106] Furthermore, the non-oriented electrical steel sheet and steel material of the present embodiment are assumed to further satisfy the following conditions as conditions for causing α-γ transformation. Specifically, when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is [P], in terms of mass %, the transformation temperature Ar3 (°C) determined by the following formula (1) is 750 to 1050°C.

[0107] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])···(1)

[0108] If the above formula (1) is not satisfied, even if the α-γ phase transformation occurs, the phase transformation point is not within the appropriate temperature range, so even if the manufacturing method described below is applied, sufficient magnetic flux density cannot be obtained. When the Ar3 phase transformation point is less than 750°C, the hot rolling temperature will be lowered, so the deformation resistance will increase, the load on the rolling mill will become too large, and the amount of element addition will increase, which may cause the toughness of the hot-rolled and cold-rolled sheets to decrease. Therefore, this value is set as the lower limit. On the other hand, when the Ar3 phase transformation point is higher than 1050°C, the hot rolling temperature is too high, so extremely high temperature heating is required, which increases the load on the heating furnace or forms a composition system that does not cause the γ→α phase transformation. Therefore, this value is set as the upper limit.

[0109] (Mn: 0.10% or more, the total of one or more selected from Mn, Ni, and Cu, or the total of one or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu is less than 2.5%)

[0110] Mn lowers the Ar3 transformation point, and in the composition system of the non-oriented electromagnetic steel sheet of this embodiment, grain refinement of the hot-rolled sheet based on phase transformation can be performed. Mn is an element that increases the electrical resistance of steel and reduces iron loss. Therefore, Mn is contained in an amount of 0.10% or more. From this point of view, Mn is preferably contained in an amount of 0.50% or more. More preferably, it is contained in an amount of 1.00% or more. On the other hand, Mn is an element that is easily segregated. When its content increases, it not only causes cold working cracks caused by segregation, but also reduces the saturation magnetic flux density, hindering the increase in the magnetic flux density of the steel sheet. In addition, MnS is excessively generated, and cold workability is reduced. Therefore, the Mn content is limited to the above range. Specifically, the upper limit of the Mn content is less than 2.5%, preferably less than 2.3% by mass, and more preferably 2.0% by mass.

[0111] (The total of one or more selected from Cu:Mn, Ni, and Cu or the total of one or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu is less than 2.5%)

[0112] Like Mn, Cu increases the electrical resistance of the steel sheet, reduces iron loss, and lowers the Ar3 transformation point. In the chemical composition of the non-oriented electrical steel sheet of this embodiment, Cu is an element that enables grain refinement in the hot-rolled sheet due to phase transformation. However, increasing the Cu content not only adversely affects texture formation during annealing after cold rolling due to increased recrystallization temperature, but also causes embrittlement during hot working. It also reduces the saturation magnetic flux density, hindering the increase in the magnetic flux density of the steel sheet, so caution is required. Therefore, the Cu content is limited to less than 2.5%. Furthermore, by adding Ni in a composite form, at least half the amount of the Cu content, Cu-induced embrittlement during hot working can be mitigated. The upper limit of the Cu content is not particularly limited, but can be 1.6% or less by mass, preferably 1.2% or less by mass, and more preferably 1.0% or less by mass. The lower limit of the Cu content is not particularly limited, but can be, for example, 0.01% or more.

[0113] (The total of one or more selected from Ni:Mn, Ni, and Cu or the total of one or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu is less than 2.5%)

[0114] Like Mn, Ni increases the electrical resistance of the steel sheet and reduces iron loss. Ni further reduces the A3 transformation point, making it possible to refine the grains based on phase transformation in the chemical composition of the non-oriented electromagnetic steel sheet of this embodiment. However, when the Ni content is too high, Ni is expensive, which increases the product cost. In addition, it also reduces the saturation magnetic flux density, hindering the increase in the magnetic flux density of the steel sheet. Therefore, these factors are preferably taken into consideration when designing the content. Therefore, the Ni content is limited to less than 2.5%. In addition, the upper limit of the Ni content is preferably 1.0% by mass or less, and more preferably 0.7% by mass or less. The lower limit of the Ni content is not particularly limited and can be set to 0%, for example, it can also be set to 0.01% or more.

[0115] (Mo: 0.0%~less than 2.5%)

[0116] Mo lowers the Ar3 transformation point and, in the chemical composition of the non-oriented electrical steel sheet of this embodiment, is an element that can refine the grain size of the hot-rolled sheet through phase transformation. Therefore, Mo can be contained as needed, but a content of 0.1% or more is preferred. On the other hand, since a Mo content of 2.5% or more significantly degrades cold workability, the Mo content is set to less than 2.5%.

[0117] (Cr: 0.0% to less than 2.5%)

[0118] Cr lowers the Ar3 transformation point. In the chemical composition of the non-oriented electrical steel sheet of this embodiment, it is an element that can refine the grain size of the hot-rolled sheet through phase transformation. In addition to improving strength and corrosion resistance, it also has a particularly effective effect of enhancing high-frequency characteristics. Therefore, Cr can be included as needed, preferably at a content of 0.1% or more. On the other hand, excessive Cr inclusion not only saturates the effect, increasing raw material costs, but also reduces the saturation magnetic flux density, hindering the increase in the magnetic flux density of the steel sheet. Therefore, the Cr content is set to less than 2.5%.

[0119] (Ti: 0.000% to 0.005%)

[0120] Ti can be dissolved or exist as TiN, thereby inhibiting recrystallization and contributing to the refinement of austenite grain size. Therefore, Ti can be contained as needed, preferably at least 0.001%. On the other hand, if the Ti content exceeds 0.005%, various precipitates such as TiN, TiS, and TiC are formed, degrading iron loss characteristics. Therefore, the Ti content is set to 0.005% or less.

[0121] (Nb: 0.000% to 0.005%)

[0122] Nb dissolves or exists as NbN, thereby inhibiting recrystallization and contributing to the refinement of austenite grain size. Therefore, Nb can be contained as needed, preferably at least 0.001%. On the other hand, if the Nb content exceeds 0.005%, various precipitates such as NbN and NbC are formed, degrading iron loss characteristics. Therefore, the content is set to 0.005% or less.

[0123] (Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%)

[0124] Sn and Sb improve the texture after cold rolling and recrystallization, increasing the magnetic flux density. Therefore, these elements can be included as needed, but excessive inclusions can embrittle the steel. Therefore, the Sn and Sb contents are both set to 0.400% or less. Furthermore, P can be included to ensure the hardness of the steel sheet after recrystallization, but excessive inclusions can cause embrittlement. Therefore, the P content is set to 0.400% or less.

[0125] In order to impart further effects such as magnetic properties, it is preferable to contain one or more selected from the group consisting of 0.020% to 0.400% of Sn, 0.020% to 0.400% of Sb, and 0.020% to 0.400% of P.

[0126] (One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0.0100% in total)

[0127] Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd react with sulfur in the molten steel during casting to form sulfides, oxysulfides, or both. Hereinafter, Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd will sometimes be collectively referred to as "coarse precipitate-forming elements." The particle size of precipitates of coarse precipitate-forming elements is approximately 1 to 2 μm, much larger than the particle size of fine precipitates such as MnS, TiN, AlN, TiC, and NbC (approximately 100 nm). Therefore, these fine precipitates adhere to the precipitates of the coarse precipitate-forming elements, making it less likely to interfere with recrystallization and grain growth during annealing processes such as intermediate annealing. To fully achieve their effects, the total content of coarse precipitate-forming elements is preferably 0.0005% or more. However, if the total content of these elements exceeds 0.0100%, sulfides, oxysulfides, or both become excessive, hindering recrystallization and grain growth during annealing such as intermediate annealing. Therefore, the content of coarse precipitate-forming elements is set to a total of 0.0100% or less. The upper limit of the total content of coarse precipitate-forming elements can be 0.0080% or less, and can also be 0.0050% or less.

[0128] In this embodiment, the remainder of the chemical composition other than those described above may be Fe and impurities. Impurities refer to elements introduced into the steel raw materials and / or during the steelmaking process. Furthermore, other elements may be included to replace a portion of the Fe, as long as they do not diminish the effects of the present invention. For example, B, O, V, Bi, W, and Y may each be included at a level of 0.10% or less. The total impurity content is preferably 5.00% or less, and more preferably 1.00% or less.

[0129] The chemical composition was determined in the following manner.

[0130] The chemical composition can be determined using standard steel analysis methods. For example, ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry) can be used. Specifically, the chemical composition is determined by measuring a test piece taken from a steel plate using a specified measuring device under conditions based on a pre-created calibration curve. C and S are measured using the combustion-infrared absorption method, while N is measured using the inert gas fusion-heat conduction method. O is measured using the inert gas fusion-non-dispersive infrared absorption method.

[0131] If there is an insulating film on the surface, it can be removed mechanically using a minitor grinder or the like before analysis.

[0132] Next, the metallographic structure of the non-oriented electrical steel sheet of the present embodiment will be described. The details of the manufacturing method will be described later, but the non-oriented electrical steel sheet of the present embodiment has a chemical composition capable of undergoing α-γ transformation.

[0133] Next, the thickness of the non-oriented electromagnetic steel sheet of the present embodiment is described. The thickness of the non-oriented electromagnetic steel sheet of the present embodiment is 0.50 mm or less. The preferred thickness of the non-oriented electromagnetic steel sheet of the present embodiment is 0.10 to 0.50 mm. Generally, the thinner the plate thickness, the lower the iron loss, but the magnetic flux density also becomes lower. Based on this point, when the plate thickness is 0.10 mm or more, the iron loss is lower and the magnetic flux density becomes higher. In addition, when the plate thickness is 0.50 mm or less, low iron loss can be maintained. The more preferred lower limit of the plate thickness is 0.20 mm, and the more preferred lower limit is 0.30 mm.

[0134] Next, the strain distribution of the non-oriented electrical steel sheet of this embodiment will be described. The non-oriented electrical steel sheet of this embodiment also has a strain distribution that produces a high magnetic flux density from the rolling direction to the 45° direction. Specifically, the non-oriented electrical steel sheet of this embodiment satisfies Sac>0.120, Sac>Sbc>Sag, and 0.050>Sag.

[0135] Next, Sac, Sag, and Sbc will be described.

[0136] Sac is the area ratio of {411} grains in any cross-section of a skin-pass rolled steel sheet, and Sag is the area ratio of {110} grains in any cross-section of a skin-pass rolled steel sheet. When observing any cross-section of a skin-pass rolled steel sheet (a ground surface after grinding the steel sheet 1 / 2 from the sheet surface side), the total area of the cross-section is denoted as Sall, the area of the {411} grains in the cross-section is denoted as Sallc, and the area of the {110} grains in the cross-section is denoted as Sallg, Sac is expressed as Sac = Sallc / Sall.

[0137] Furthermore, Sag is expressed as Sag = Salg / Salg. {411} grains (or {110} grains) are defined as grains that fall within a tolerance of 10° from the target crystal orientation. In other words, the crystal orientation has a tolerance of ±10° from the target crystal orientation.

[0138] Sbc is the area ratio of {411} grains in the region with a specified KAM value. Sbc is defined as follows: In the same cross-section as above, the total area of the region from the higher KAM (Kernel Average Misorientation) value to 20% is defined as Ssab, and the area occupied by {411} grains in the region from the higher KAM value to 20% is defined as Ssabc. Sbc is expressed as Sbc = Ssabc / Ssab.

[0139] The KAM value represents the orientation difference between a certain measurement point and an adjacent measurement point within the same grain (wherein, when the adjacent measurement point is another grain, the adjacent measurement point is excluded from the calculation of KAM). The KAM value increases at a location with a lot of strain. By extracting the area from the side with a high KAM value to 20%, only the high strain area can be extracted. The measurement point is an area composed of arbitrary pixels. In addition, the size of the pixels constituting the measurement point is preferably 0.1 to 1.0 μm from the perspective of accurately obtaining the KAM value.

[0140] The area from the side with a high KAM value to 20% is obtained as follows. First, a histogram representing the degree distribution of the KAM value in the above-mentioned cross section is prepared. The histogram represents the degree distribution of the KAM value in the above-mentioned cross section. Next, the histogram is converted into a cumulative histogram. Then, in the cumulative histogram, a range from the side with a high KAM value to 20% of the cumulative relative degree (0 to 20%) is determined. Then, the area (a) where the KAM value in this range is obtained is defined (mapped) on the above-mentioned cross section as "the area from the side with a high KAM value to 20%". That is, the area of the area (a) thus defined is Ssab. Next, in the above-mentioned cross section, the area (b) of the {411} grains is defined, and the area (c) where the area (a) and the area (b) overlap is obtained. The area of the area (c) thus defined is Ssabc.

[0141] Furthermore, regarding Sallc, Sallg, Ssabc, etc., these do not strictly represent the area of grains of each orientation; for example, they are assumed to include the area of orientations that allow a deviation (tolerance) of up to 10° from each orientation. In other words, the area ratio of grains of the target crystal orientation is the area ratio of grains having a crystal orientation within ±10° of the target crystal orientation.

[0142] The KAM value is calculated by analyzing images of the sample cross section using software such as OIM Analysis. The highest KAM value is automatically assigned by the same software. In the above description, the term "high KAM value side" refers to the side with the highest KAM value in the KAM value frequency distribution. For example, in the case of a cumulative histogram with a KAM value of 0 as the origin, the range from the high KAM value side to 20% of the cumulative relative frequency refers to the range of cumulative relative frequencies between 1 and 0.8.

[0143] In the non-oriented electrical steel sheet of the present embodiment, the metallographic structure is determined in a cross section parallel to the sheet surface of the steel sheet, and is determined by the following procedure.

[0144] First, the plate is polished in such a way that half of the thickness is exposed, and the polished surface (the polished surface after polishing 1 / 2 from the plate side of the steel plate) is observed by EBSD (Electron Back Scattering Diffraction) using an SEM with an acceleration voltage of 25kV and a magnification of 1000 times. The observation field is set to 500μm×500μm. Observation can also be performed at several locations divided into several small partitions. The step interval during measurement is set to 0.3μm. Based on the EBSD observation data, the following types of areas and KAM (Kernel Average Misorientation) values are obtained by general methods.

[0145] The area of each orientation can be obtained by calculating the IPF (Inverse Pole Figure) from the observation field of EBSD. The KAM value can be obtained by calculating the orientation difference between the measurement points using software such as OIM Analysis. In the present disclosure, OIM Analysis 7.3 is used, and the limit (tolerance) for entering the KAM value is set to an orientation difference of less than 5° with adjacent pixels, and the average value of the values obtained by calculating the orientation difference between the most adjacent (1st neighbor) measurement points is used as the KAM value. In addition, the setting of "Set zero point kernel to maximum misorientations: Set the zero point kernel to maximum deviation" is in the default state and entered into the inspection.

[0146] In the non-oriented electrical steel sheet of the present embodiment, when Sac is 0.120 or less, even if the relationships Sac>Sbc>Sag and 0.050>Sag are satisfied, grain growth occurs and excellent magnetic properties cannot be obtained. Therefore, Sac satisfies Sac>0.120.

[0147] The relationship Sac > Sag in the above inequality indicates that the proportion of {411} grains is greater than that of {110} grains. During annealing after skin-pass rolling, both {411} and {110} grains tend to grow. In this regard, {411} grains exhibit superior magnetic properties compared to {110} grains at 45° from the rolling direction, so increasing the number of {411} grains is preferable.

[0148] Next, the relationship Sac > Sbc indicates that the {411} grains have relatively few regions with high strain. It is known that during annealing after skin-pass rolling, grains with low strain cannibalize grains with high strain. Therefore, this inequality indicates that {411} grains tend to grow more easily.

[0149] In the non-oriented electrical steel sheet of this embodiment, since {411} grains grow and the {411} grains are more likely to grow, the area ratio Sag of {110} grains is less than 0.05. If the area ratio Sag of {110} grains exceeds 0.05, excellent magnetic properties cannot be achieved. Furthermore, the reason for setting Sbc>Sag is that a higher proportion of {411} grains in the high-strain region compared to the proportion of {110} grains improves the magnetic properties in the direction 45° from the rolling direction.

[0150] Next, the magnetic properties of the non-oriented electrical steel sheet of this embodiment will be described. The non-oriented electrical steel sheet of this embodiment is a final annealed sheet. Of the three angles with respect to the rolling direction (0°, 45°, and 90°), the magnetic properties in the 45° direction are the most excellent. In this embodiment, the magnetic properties in the 45° direction are the average of the magnetic properties in the two directions (+45° and -45°) with respect to the rolling direction.

[0151] When measuring the magnetic flux density of the non-oriented electrical steel sheet of this embodiment, the magnetic flux density B in the rolling direction is 50 The magnetic flux density B is 1.58T or more and is 45° relative to the rolling direction. 50 It is preferably 1.70T or more.

[0152] In the non-oriented electrical steel sheet of this embodiment, the magnetic flux density B in the rolling direction is 50 The value of B 50L , the magnetic flux density B in the direction of 45° relative to the rolling direction 50 The value of B 50D , the magnetic flux density B in the direction 90° relative to the rolling direction 50 The value of B 50C When B 50D Relatively high, followed by B 50L High, B 50CThe anisotropy of such magnetic flux density is relatively low.

[0153] The magnetic flux density can be measured by cutting out a 55 mm square sample from a direction such as 45° or 0° relative to the rolling direction and using a single-plate magnetic measuring device.

[0154] Next, an example of a method for producing a non-oriented electrical steel sheet according to the present embodiment will be described. The non-oriented electrical steel sheet according to the present embodiment is obtained by a production method including a hot rolling step, a cold rolling step, an intermediate annealing step, a skin pass rolling step, and a final annealing step.

[0155] Next, preferred conditions for each step will be described.

[0156] Hereinafter, in this embodiment, the Ar3 temperature is the phase transition temperature Ar3 (° C.) determined by the above formula (1).

[0157] (Hot rolling process)

[0158] In the hot rolling process, the steel material meeting the above chemical composition is hot rolled to produce hot-rolled steel sheets. The hot rolling process includes a heating process and a rolling process.

[0159] Steel materials, for example, are steel billets produced by conventional continuous casting. Steel materials with the aforementioned composition are produced using known methods. For example, molten steel is produced using a converter or electric furnace. The produced molten steel is then subjected to secondary refining using vacuum degassing equipment or the like to obtain the molten steel having the aforementioned chemical composition (the chemical composition remains substantially unchanged in subsequent steps). The molten steel is then used to cast steel billets using continuous casting or ingot casting. The cast steel billets may also be subjected to bloom rolling.

[0160] During the heating process, the steel material having the aforementioned chemical composition is preferably heated to 1000-1200°C. Specifically, the steel material is placed in a heating furnace or soaking pit and heated within the furnace. The time the steel material is held at the aforementioned heating temperature within the heating furnace or soaking pit is not particularly limited, but is, for example, 30-200 hours.

[0161] During the rolling process, the steel material heated by the heating process is subjected to a plurality of rolling passes to produce hot-rolled steel sheets. Here, the term "pass" refers to the steel sheet being pressed down by a rolling mill stand having a pair of work rolls. Hot rolling can be performed by, for example, a tandem rolling mill comprising a plurality of rolling mill stands arranged in a row (each having a pair of work rolls) and performing a plurality of rolling passes, or by reverse rolling using a pair of work rolls and performing a plurality of rolling passes. From the perspective of productivity, it is preferred to use a tandem rolling mill and perform a plurality of rolling passes.

[0162] The rolling process (rough rolling and final rolling) heats the above-mentioned steel material and performs hot rolling. The steel material is, for example, a steel billet manufactured by conventional continuous casting. The heating of the steel billet is set to a temperature range above the Ar3 temperature where the steel structure becomes a γ phase. Hot rolling starts in a temperature range where the steel structure becomes a γ phase (hereinafter, this temperature range is sometimes referred to as the γ range), and is carried out in the γ range except for the necessary number of passes including the final pass of final rolling. The necessary number of passes including the final pass are carried out in the temperature range where the α phase exists in the steel structure (hereinafter, this temperature range is sometimes referred to as the α range), thereby completing the rolling process. Generally speaking, the front to middle sections of rough rolling and final rolling are carried out in the γ range, and the rear section of finish rolling is carried out in the α range. In this embodiment, the total reduction rate in the temperature range above the Ar3 temperature and below Ar3+20°C before rolling in the final α range is set to 10% or more. Furthermore, the reduction ratio in the temperature range of the finishing temperature FT or higher and lower than the Ar3 temperature is set to 15% or higher in total, taking into account the case of rolling in multiple passes.

[0163] The finishing temperature FT refers to the surface temperature of the hot-rolled steel sheet after finishing rolling.

[0164] The lower limit of the finishing temperature FT is not particularly limited, and may be, for example, Ar3 temperature - 100°C or higher.

[0165] Rolling in a temperature range higher than Ar3+20°C before rolling in the final α domain has almost no effect on the particle size of the processed γ grains before the phase transformation. Coarse processed α grains are formed after the phase transformation, which has nothing to do with the accumulation of {411} crystal orientation in the final product.

[0166] If the rolling ratio in the temperature range of Ar3 to Ar3+20°C before final α-region rolling is less than 10%, strain accumulation in the processed γ grains before phase transformation will be insufficient, resulting in coarse processed α grains and making it difficult to achieve accumulation of {411} crystal orientation in the final product. The rolling ratio in the temperature range of Ar3 to Ar3+20°C is preferably set to 15% or higher. There is no upper limit for the total reduction ratio, but if it exceeds 40%, the mill load becomes too high. Therefore, 40% is preferably set as the upper limit, and 30% or lower is more preferred.

[0167] If the total reduction ratio in the final α region within the temperature range from the final rolling temperature FT to less than the Ar3 temperature is less than 15%, the processing strain in the α region cannot be sufficiently accumulated in the processed α grains after transformation from the processed γ grains, making it difficult to achieve accumulation of the {411} crystal orientation in the final product. The reduction ratio in the temperature range from the final rolling temperature FT to less than the Ar3 temperature is preferably set to 20% or more. While there is no specified upper limit for the total reduction ratio, if it exceeds 40%, the mill load becomes excessively high. Therefore, 40% is preferably set as the upper limit, and 30% or less is more preferred.

[0168] Furthermore, the total rolling reduction ratio at the finishing rolling temperature FT or higher and less than Ar3-20°C is preferably higher than 10%.

[0169] In the present embodiment, the rolling reduction ratio RR0 in hot rolling is defined as follows.

[0170] Reduction ratio RR0 (%) = (1 - plate thickness after rolling in the temperature range of hot rolling / plate thickness before rolling in the temperature range of hot rolling) × 100

[0171] The lower limit temperature of rolling in the α range is not particularly limited, but since a lower rolling temperature increases the load on the rolling mill, it is preferably set to 600° C. or higher.

[0172] Furthermore, the rolling temperature is believed to fluctuate around a predetermined determination temperature (Ar3 temperature, or Ar3 + 20°C) during the rolling pass due to competition between the temperature drop caused by roll contact and the cooling lubricant and the temperature rise caused by processing. In this embodiment, this situation is handled as follows.

[0173] In a rolling pass, let the entry temperature be TPI (°C), the entry thickness be TCI (mm), the exit temperature be TPO (°C), and the exit thickness be TCO (mm). Furthermore, it is assumed that the thickness change and temperature change during the rolling pass have a simple linear relationship. Specifically, if the thickness at a specific time during the rolling pass is TCa (mm) and the temperature is TPa (°C), it is assumed that the following equation always holds true during the rolling pass.

[0174] (TCa-TCO) / (TCI-TCO)=(TPa-TPO) / (TPI-TPO)

[0175] Thus, even when the predetermined determination temperature (Ar3 temperature, or Ar3+20° C.) in the present manufacturing method is reached during the rolling pass, the plate thickness at that time can be determined.

[0176] That is, the plate thickness TCa (mm) at the time when the specific temperature TPa (°C) is reached during the rolling pass can be

[0177] TCa = TCO + (TCI - TCO) × (TPa - TPO) / (TPI - TPO) is obtained.

[0178] Note that the above assumptions also assume that the exit temperature of the rolling pass is higher than the entry temperature. Specifically, even if a steel plate with an entry temperature TPI lower than the Ar3 temperature rises in temperature during the pass due to working heat and is discharged at an exit temperature TPO higher than the Ar3 temperature, rolling in the γ range (a temperature range between Ar3 and Ar3+20°C) required by the present disclosure is performed in the latter half of the pass.

[0179] In addition, it is also considered that the temperature fluctuation between the Ar3 temperature is generated in multiple passes. In such a case, in this embodiment, regarding the rolling conditions in the α domain, the "final rolling process in the α domain" is taken as the target. In addition, regarding the rolling conditions in the γ domain, the "rolling process in the γ domain before the above-mentioned 'final rolling process in the α domain'" is taken as the target. That is, the rolling temperature after starting hot rolling in the γ domain is set to the temperature in the γ domain (starting hot rolling). domain domain domain domain When the form of the domain 3 (rolling end) is changed, if the α domain 3 and the γ domain 2 meet the conditions of this embodiment, the steel sheet of the present disclosure can be obtained.

[0180] The rolling temperature during each pass can be measured, for example, using a thermometer installed on the entry or exit side of the rolling stand performing the desired pass. Furthermore, thermometers do not need to be installed on all entry and exit sides of a rolling stand within the temperature range disclosed herein. The rolling temperature in an intermediate rolling stand can be calculated based on the actual temperatures of thermometers appropriately installed before and after the roll stand. Instead, current hot rolling typically utilizes temperature control derived from such calculations.

[0181] Furthermore, the finishing rolling temperature FT is preferably set to be lower than the Ar3 temperature.

[0182] Afterward, the hot-rolled steel sheet is coiled without annealing. The coiling temperature is preferably above 250°C and below 600°C. Coiling the hot-rolled steel sheet at above 250°C and below 600°C after hot rolling can refine the crystal structure before cold rolling and increase the {411} crystal orientation, which exhibits excellent magnetic properties, during expansion. Based on this perspective, the coiling temperature is preferably between 350°C and 550°C, and even more preferably between 400°C and 480°C.

[0183] (Cold rolling process)

[0184] In the cold rolling process, the hot-rolled steel sheet after the cooling process is cold-rolled to obtain a cold-rolled steel sheet. Specifically, after hot rolling, the hot-rolled steel sheet is pickled and then cold-rolled. In the cold rolling, the reduction ratio is preferably set to 80% to 92%. The lower limit of the reduction ratio can be set to 83% or more, and further can be set to 85% or more. In addition, the upper limit of the reduction ratio can also be set to 90% or less. It should be noted that the higher the reduction ratio, the easier it is for grains with a {411} crystal orientation to grow through subsequent expansion, but the plate shape will deteriorate and handling will become difficult.

[0185] (Intermediate annealing process)

[0186] In the intermediate annealing step, the cold-rolled steel sheet is subjected to intermediate annealing. In this embodiment, the intermediate annealing temperature is controlled to be between 650°C and less than 700°C. When the intermediate annealing temperature is above 700°C, excessive grain growth occurs, making it difficult to aggregate toward the {411} crystal orientation even after skin-pass rolling and final annealing, which will be described later, and promoting the development of {110} grains. In addition, if sufficient recrystallization does not occur at the intermediate annealing temperature below 650°C, the growth of grains with the {411} crystal orientation will be hindered even after skin-pass rolling and final annealing, which will be described later. Therefore, the intermediate annealing temperature is preferably set to 650°C or above. The lower limit of the intermediate annealing temperature can be set to 660°C or above, and can also be set to 680°C or above. The temperatures described here are based on continuous annealing, and the intermediate annealing time is preferably in the range of 5 to 120 seconds. It is believed that this annealing temperature range and annealing time range are appropriate conditions, allowing the large number of {411} grains generated before the cold rolling process to grow appropriately due to expansion, and to achieve a state where strain-induced grain growth is easily caused by the skin pass rolling and final annealing described later.

[0187] (Skin-pass rolling process)

[0188] In the skin-pass rolling process, the steel sheet after the intermediate annealing process is skin-pass rolled. As described above, when skin-pass rolling and annealing are performed in a state where the {411} crystal orientation is enriched due to expansion, grains with the {411} crystal orientation further grow. This is because skin-pass rolling has the following properties: strain is less likely to accumulate in grains with the {411} crystal orientation, while strain easily accumulates in grains belonging to the {111} plane orientation group, which is known as γ-fiber, such as {111}<112> or {111}<110>. During subsequent annealing, grains with the less strained {411} crystal orientation erode these γ-fiber oriented grains, driven by the strain difference. This erosion phenomenon, driven by the strain difference, is called strain-induced grain boundary migration (SIBM). The skin-pass rolling reduction ratio is preferably set to 5% to less than 20%. When the reduction ratio is less than 5%, the strain is too small, so strain-induced grain boundary migration (hereinafter referred to as SIBM) does not occur during subsequent annealing, and grains with a {411} crystal orientation do not grow larger. On the other hand, when the reduction ratio is 20% or more, the strain becomes too large, and recrystallization nucleation (hereinafter referred to as nucleation) occurs, in which new grains are generated from grains with a γ-fiber orientation. The grains generated during this nucleation are mostly grains with a γ-fiber orientation, so the magnetic properties deteriorate. Based on this viewpoint, the reduction ratio for skin-pass rolling is preferably set to 8% to 15%.

[0189] In addition, in the non-oriented electrical steel sheet, when it is set to have the above-mentioned strain distribution, when the reduction rate (%) of cold rolling is set to RR1 and the reduction rate (%) during skin-pass rolling is set to RR2, it is preferred to adjust the reduction rates of cold rolling and skin-pass rolling in a manner that satisfies 88<RR1+0.2×RR2<93 and 5≦RR2<20.

[0190] Here, the reduction ratio RR1 (%) in cold rolling is defined as follows.

[0191] Reduction ratio RR1 (%) = (1 - plate thickness after final cold rolling pass / plate thickness before first cold rolling pass) × 100

[0192] In addition, the reduction ratio RR2 (%) in skin pass rolling is defined as follows.

[0193] Reduction ratio RR2 (%) = (1 - plate thickness after final pass in skin-pass rolling / plate thickness before first pass in skin-pass rolling) × 100

[0194] (Final annealing process)

[0195] In the final annealing step, the skin-pass rolled steel sheet undergoes final annealing. This final annealing generates SIBM, driven by the strain differences between different crystal orientations caused by skin-pass rolling. Grains with the {411} crystal orientation, targeted by the present disclosure, preferentially grow, increasing the concentration of the {411} crystal orientation in the steel sheet. The annealing conditions can be appropriately set by those skilled in the art to confirm the occurrence of SIBM. While not particularly limited, annealing at 800°C for 2 hours is an example.

[0196] The non-oriented electrical steel sheet of the present embodiment can be manufactured as described above.

[0197] This final annealing can be performed after skin-pass rolling, for example, at the steel sheet manufacturer, either in coil form or as cut sheets. Alternatively, the steel sheets can be shipped without final annealing after skin-pass rolling, and then processed into the desired shape for the motor core by the motor manufacturer, laminated, and then annealed into the core form. In the latter case, this can also serve as the strain relief annealing typically performed on motor cores at the motor manufacturer.

[0198] If the steel sheet manufacturer performs final annealing before shipping, motor manufacturers can use the steel sheet disclosed herein to achieve excellent motor properties. Furthermore, if the steel sheet manufacturer ships the steel sheet after skin pass rolling, and the motor manufacturer processes the steel sheet into motor cores and then performs final annealing as strain relief, excellent motor properties can also be achieved using the steel sheet disclosed herein.

[0199] Steel components made of the non-oriented electromagnetic steel sheets of this embodiment are suitable for use, for example, as cores for rotating electrical machines (motor cores). In this case, the cores for rotating electrical machines are manufactured by cutting individual flat sheets from the non-oriented electromagnetic steel sheets of this embodiment and stacking these flat sheets as appropriate. By utilizing the non-oriented electromagnetic steel sheets with excellent magnetic properties, the cores have low iron loss, enabling the realization of rotating electrical machines with excellent torque. Steel components made of the non-oriented electromagnetic steel sheets of this embodiment can also be used in products other than cores for rotating electrical machines, such as cores for linear motors and static machines (reactors or transformers).

[0200] [Example]

[0201] Next, the non-oriented electrical steel sheet according to the embodiment of the present disclosure will be specifically described with reference to examples. The following examples are merely examples of the non-oriented electrical steel sheet according to the embodiment of the present disclosure, and the non-oriented electrical steel sheet according to the present disclosure is not limited to the following examples.

[0202] Molten steel was cast to produce steel ingots having the compositions shown in Table 1 below. Note that "Co, etc." in Table 1 indicates the contents of Co, Pt, Pb, and Au. The resulting steel ingots were then subjected to hot rolling, cold rolling, intermediate rolling, skin pass rolling, and final annealing under the conditions shown in Table 2. The final annealing was performed at the temperature shown in Table 2 for 2 hours.

[0203] Furthermore, regarding the above-mentioned method, the following specific investigations were conducted.

[0204] Phase transition temperature Ar3 (℃)

[0205] ·Plate thickness

[0206] Area ratio of {411} grains Sac

[0207] Area ratio of {110} grains Sag

[0208] The area ratio Sbc of {411} grains in the region from the high KAM value side to 20%

[0209] Magnetic flux density B in the rolling direction 50L

[0210] Magnetic flux density B at 45° relative to the rolling direction 50D

[0211] Magnetic flux density B at 90° relative to the rolling direction 50C

[0212] To investigate the texture of the skin-pass rolled steel, a portion of the skin-pass rolled steel sheet was removed and the specimen was reduced to 1 / 2 thickness. EBSD observation (step interval: 0.3 μm) was performed on this processed surface (the ground surface of the steel sheet after grinding 1 / 2 from the plate surface) using the aforementioned conditions. Using OIM Analysis 7.3, the areas of the oriented grains of the types listed in Table 3 were determined through EBSD observation.

[0213] Next, 55mm square specimens were taken from the final annealed steel sheets as test specimens. Samples with one side parallel to the rolling direction and those tilted 45 degrees relative to the rolling direction were used. Samples were taken using a shearing machine.

[0214] Furthermore, the magnetic flux density B in the rolling direction was measured according to JIS C 2556 (2015). 50L , magnetic flux density B at 45° relative to the rolling direction 50D , magnetic flux density B at 90° relative to the rolling direction 50C Table 3 shows the measurement results.

[0215] In addition, the following evaluations were performed.

[0216] (Rolling properties)

[0217] Rollability was evaluated as follows: If two or more cracks of 1 cm or more occurred on both end surfaces of the cold-rolled sheet coil in the longitudinal direction, within a 1-meter-long region centered at a position 10 m in the longitudinal direction (top) from the outermost circumference of the coil, a position halfway along the entire longitudinal length of the coil (middle), and a position 10 m in the longitudinal direction from the innermost circumference of the coil (bottom), the result was marked as "N"; otherwise, the result was marked as "Y."

[0218] In this embodiment, the rollability of a cold-rolled steel coil is evaluated. However, when evaluating steel plates cut from the cold-rolled steel coil, the end surfaces on both sides of the steel plate in the longitudinal direction (rolling direction) can also be observed at three or more different positions in the longitudinal direction (rolling direction) of the steel plate, in the same manner as described above. For example, observation can be performed in an area of approximately 1 / 10 of the entire longitudinal length of the steel plate, centered at positions approximately 1 / 10, 1 / 2, and 9 / 10 of the longitudinal length of the steel plate. The entire longitudinal length of the steel plate can be set to at least 1 meter.

[0219] [Table 1-1]

[0220]

[0221] [Table 1-2]

[0222]

[0223] [Table 2-1]

[0224]

[0225] [Table 2-2]

[0226]

[0227] [Table 3-1]

[0228]

[0229] [Table 3-2]

[0230]

[0231] As can be understood from the above examples, the non-oriented electrical steel sheet disclosed herein exhibits excellent magnetic properties at 45° from the rolling direction by appropriately controlling the chemical composition, hot rolling conditions, cold rolling conditions, intermediate annealing conditions, skin pass rolling conditions, and final annealing process conditions. Furthermore, rollability is not a problem.

[0232] Industrial applicability

[0233] According to the present disclosure, since it is possible to provide a non-oriented electrical steel sheet that has no problem with rollability and can obtain excellent magnetic properties in a direction 45° from the rolling direction, it is extremely useful industrially.

[0234] In addition, the disclosure of Japanese Patent Application No. 2023-001936 is incorporated herein by reference in its entirety.

[0235] All documents, patent applications, and technical specifications described in this specification are incorporated herein by reference to the same extent as if each document, patent application, or technical specification were specifically and individually described as being incorporated by reference.

Claims

1. A non-oriented electromagnetic steel sheet having the following chemical composition: By mass, contains C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001%~1.0%, S: 0.0100% or less, N: 0.0100% or less, Mn: 0.10% or more, One or more selected from Mn, Ni, and Cu: less than 2.50% in total, Mo: 0.00% to less than 2.50%, Cr: 0.00% to less than 2.50%, Ti: 0.000% to 0.005%, Nb: 0.000% to 0.005%, Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%, and One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0.0100% in total, When the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is [P], the phase transition temperature Ar3 (°C) determined by the following formula (1) is 750 to 1050°C, and the remainder is composed of Fe and impurities. Moreover, the plate thickness is less than 0.50 mm. In any cross section, the area ratio of {411} grains is defined as Sac, the area ratio of {110} grains is defined as Sag, and the area ratio of {411} grains in the region from the side with the highest core average orientation difference to 20% is defined as Sbc. If Sac>0.120, Sac>Sbc>Sag, and 0.050>Sag are satisfied, Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])···(1).

2. A non-oriented electromagnetic steel sheet having the following chemical composition: By mass, contains C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001%~1.0%, S: 0.0100% or less, N: 0.0100% or less, Mn: 0.10% or more, One or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu: less than 2.50% in total, Mo: 0.00% to less than 2.50%, Cr: 0.00% to less than 2.50%, Ti: 0.000% to 0.005%, Nb: 0.000% to 0.005%, Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%, and One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0.0100% in total, When the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is [P], the phase transition temperature Ar3 (°C) determined by the following formula (1) is 750 to 1050°C, and the remainder is composed of Fe and impurities. Moreover, the plate thickness is less than 0.50 mm. In any cross section, the area ratio of {411} grains is defined as Sac, the area ratio of {110} grains is defined as Sag, and the area ratio of {411} grains in the region from the side with the highest core average orientation difference to 20% is defined as Sbc. If Sac>0.120, Sac>Sbc>Sag, and 0.050>Sag are satisfied, Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])···(1).

3. The non-oriented electrical steel sheet according to claim 1 or 2, Magnetic flux density B in rolling direction 50 The magnetic flux density B is 1.58T or more and is 45° to the rolling direction. 50 More than 1.70T.

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