Non-oriented electrical steel sheet, non-oriented electrical steel sheet, core, cold-rolled steel sheet, non-oriented electrical steel sheet manufacturing method, non-oriented electrical steel sheet manufacturing method, and

Abstract

The non-oriented electrical steel sheet has a prescribed chemical composition satisfying the following conditions: 1020-325 * [C] + 33 * [Si] + 287 * [P] + 80 * [sol.Al]-120 * ([Mn] + [Mo] + [Cu])-46 * ([Cr] + [Ni]): 750-1050: {hkl} lt when a surface parallel to a rolling surface at a depth of 1 / 2 of the sheet thickness from the surface is measured by SEM-EBSD; uvwgt, uvwgt; when the area ratio of oriented crystal grains with respect to the total field of view is Ahkl-uvw, A411-011 is 15.0% or more, and in ODF at [phi] 2 = 45 degrees, the crystal grains have a maximum strength at # imgabs 1 # at # imgabs 0 # [phi] = 20 degrees and a maximum strength at [phi] = 5-35 degrees at # imgabs 2 # [phi] = 0-90 degrees, and the average crystal grain size is 50-150 [mu] m.

Description

Technical Field

[0001] The present disclosure relates to a non-oriented electromagnetic steel sheet, a base sheet of the non-oriented electromagnetic steel sheet, an iron core, a cold-rolled steel sheet, a method for producing the non-oriented electromagnetic steel sheet, a method for producing the base sheet of the non-oriented electromagnetic steel sheet, and a method for producing the cold-rolled steel sheet. Background Art

[0002] Electromagnetic steel sheets are used as raw materials for the iron cores of motor equipment. Examples of motor equipment include drive motors installed in automobiles, motors for various compressors such as those used in air conditioners and refrigerators, and generators for household or industrial use. These motor equipment require high energy efficiency, miniaturization, and high output. Therefore, low iron loss and high magnetic flux density are required for electromagnetic steel sheets used as the iron cores of motor equipment. Texture control is a solution for achieving low iron loss and high magnetic flux density. So far, a technology has been proposed that allows the development of a structure (α fiber) that has an easy magnetization axis within the surface of the steel sheet, is beneficial for improving magnetic properties, and can be relatively easily improved through rolling processing in hot rolling and cold rolling, which are necessary processes for manufacturing steel sheets. Specifically, the formation <110> A structure whose orientation is roughly parallel to the rolling direction (RD).

[0003] Patent documents 1 to 3 all disclose the use of {100} <011> As a method for developing orientation, it is described that the phase transformation temperature is lowered and the structure is refined by rapid cooling after hot rolling.

[0004] Specifically, Patent Document 1 describes cooling to 250°C or below at a cooling rate of 200°C / sec or above within 3 seconds after hot rolling, without annealing between hot rolling and cold rolling, and making the cumulative reduction ratio in cold rolling 88% or above. <011> Oriented concentrated electromagnetic steel sheet.

[0005] In addition, Patent Document 2 discloses a method for manufacturing an electromagnetic steel sheet containing 0.6 mass % or more and 3.0 mass % or less of Al. By the same process as the method described in Patent Document 1, it is possible to manufacture an electromagnetic steel sheet having {100} <011> Oriented concentrated electromagnetic steel sheet.

[0006] On the other hand, Patent Document 3 describes that the finishing rolling temperature in hot rolling is set to above the Ac3 transformation point, and the steel plate temperature is cooled to 250°C within 3 seconds after hot rolling, or the finishing rolling temperature is set to below the Ac3 transformation point - 50°C, and the steel plate is cooled at a cooling rate higher than the cooling rate after standing. In addition, the manufacturing method described in Patent Document 3 is a method of performing two cold rollings with intermediate annealing, in which no annealing is performed between the hot rolling and the first cold rolling, and the cumulative reduction rate in the second cold rolling is set to 5-15%. In this way, it is possible to manufacture a steel plate having a surface area of {100} <011> Upward-oriented electromagnetic steel sheets.

[0007] In any of the methods described in Patent Documents 1 to 3, a steel plate surface is produced at {100} <011> When hot rolling is performed at a finishing temperature of Ac3 or higher in an upwardly oriented electromagnetic steel sheet, subsequent rapid cooling is necessary. Rapid cooling increases the cooling load after hot rolling. Considering operational stability, it is preferable to minimize the load on the rolling mill performing cold rolling.

[0008] Meanwhile, to improve magnetic properties, a technique has been proposed for developing the {411} orientation, which is rotated 20° from the {100} orientation. Patent Documents 4 to 7 all disclose techniques for developing the {411} orientation, describing methods for optimizing the grain size in hot-rolled sheets and reinforcing the α fibers in the texture of hot-rolled sheets.

[0009] Specifically, Patent Document 4 describes cold rolling a hot-rolled sheet with a higher concentration of the {211} orientation than the {411} orientation, with the cumulative reduction ratio during cold rolling being 80% or greater. This enables the production of an electromagnetic steel sheet with a concentration of the {411} orientation on the sheet surface.

[0010] Patent Documents 5 and 6 describe setting the slab heating temperature to 700°C to 1150°C, the start temperature of finish rolling to 650°C to 850°C, the end temperature of finish rolling to 550°C to 800°C, and the cumulative reduction ratio during cold rolling to 85-95%. This allows the production of electromagnetic steel sheets with a concentration of {100} and {411} orientations on the steel sheet surface.

[0011] On the other hand, Patent Document 7 describes that in a method for producing a non-oriented electrical steel sheet, if α fibers are developed in a hot-rolled coil steel sheet near the surface layer by strip casting or the like, then in the subsequent hot-rolled sheet annealing, the {h11}<1 / h12> orientation, particularly the {100} <012> ~{411} <148> orientation will undergo recrystallization.

[0012] Furthermore, in order to promote the development of the {100} crystal orientation that improves magnetic properties, various studies have been conducted on component systems that induce a γ→α phase transition, as shown in Patent Documents 8 to 12.

[0013] Furthermore, Technical Document 13 discloses a steel sheet having stress sensitivity and excellent magnetic properties in the 45° direction.

[0014] Prior art literature

[0015] Patent Literature

[0016] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-145462

[0017] Patent Document 2: Japanese Patent Application Laid-Open No. 2017-193731

[0018] Patent Document 3: Japanese Patent Application Publication No. 2019-178380

[0019] Patent Document 4: Japanese Patent No. 4218077

[0020] Patent Document 5: Japanese Patent No. 5256916

[0021] Patent Document 6: Japanese Patent Application Laid-Open No. 2011-111658

[0022] Patent Document 7: Japanese Patent Application Publication No. 2019-183185

[0023] Patent Document 8: Japanese Patent No. 4029430

[0024] Patent Document 9: Japanese Patent No. 6319465

[0025] Patent Document 10: WO2021 / 095846

[0026] Patent Document 11: Japanese Patent Application Publication No. 2021-080501

[0027] Patent Document 12: Japanese Patent Application Laid-Open No. 2020-100860

[0028] Patent Document 13: WO2021 / 205880 Summary of the Invention

[0029] Technical problem to be solved by the invention

[0030] The present inventors have studied the above technology and found that if the {100} <011> Orientation to improve magnetic properties requires rapid cooling after hot rolling, which has the problem of high manufacturing load. <011> When oriented steel sheets are used as raw materials for riveted cores, the core properties expected from the raw materials may not be obtained. The reason for this is considered to be {100} <011> The change in magnetic properties due to orientation with respect to stress, specifically, the deterioration of magnetic properties (stress sensitivity), particularly the deterioration of iron loss, when compressive stress acts, increases.

[0031] In addition, it was found that in the techniques of Patent Documents 4 to 7, although the {411} orientation was developed, the in-plane orientation <011> The orientation is weak, and the magnetic properties in the direction of 45° to the rolling direction of the steel sheet, which are the characteristics of α fibers, are not sufficiently improved. <011> The misalignment of orientation, that is, the large deviation of α fibers, is the main factor that hinders aggregation to the {411} orientation as a plane orientation, and causes insufficient improvement in magnetic properties.

[0032] In the technologies of Patent Documents 8 to 12, which investigate compositional systems that induce a γ→α transformation to promote the development of the {100} crystal orientation, which improves magnetic properties, a key focus is on refining the hot-rolled structure. To achieve this, a steel composition with a low γ→α transformation temperature is used. During hot rolling in the low-temperature γ region, a large amount of strain is accumulated in the γ phase, which then undergoes a phase transformation, resulting in a fine-grained α phase structure in the hot-rolled sheet. To lower the transformation temperature and delay recrystallization recovery, thereby promoting strain accumulation, the addition of γ-stabilizing elements such as Mn, Cu, and Ni is effectively utilized.

[0033] However, Mn is known as a segregating element. If the amount added increases, it will segregate in the center of the plate thickness of the hot-rolled plate, causing cracks in the hot-rolled plate. In addition, Cu significantly reduces hot brittleness. Regarding Ni, although the problem of hot workability is small, it has the effect of improving the hot brittleness caused by Cu. However, due to the high alloy cost, it is not actively used.

[0034] In addition, the {100} crystal orientation, which has been developed in the technology of effectively utilizing the γ→α phase transition, is difficult to be random in the plane, so the {100} <011> Since orientation is dominant, it cannot be said that the reduction of in-plane anisotropy is sufficient, and a different crystal orientation control than before is required.

[0035] Furthermore, the technology of Patent Document 13, which discloses a steel sheet having stress sensitivity and excellent magnetic properties in the 45° direction, requires the addition of γ-stabilizing elements such as Mn, Cu, and Ni, and hot brittleness and alloy cost become problems.

[0036] In view of the above-mentioned problems, the present invention aims to provide a non-oriented electrical steel sheet having a chemical composition in which the content of γ-stabilizing elements such as Mn, Cu, and Ni is suppressed to avoid hot brittleness and alloy cost problems, thereby achieving low stress sensitivity, particularly a low iron loss degradation rate due to stress, and excellent magnetic properties in the 45° direction; an iron core using the non-oriented electrical steel sheet; a base sheet of the non-oriented electrical steel sheet for producing the non-oriented electrical steel sheet; a cold-rolled steel sheet; a method for producing the non-oriented electrical steel sheet; a method for producing the base sheet of the non-oriented electrical steel sheet; and a method for producing the cold-rolled steel sheet.

[0037] Technical means for solving technical problems

[0038] The present inventors have conducted intensive research to solve the above problems. As a result, it was found that the chemical composition, the {411} <011> It is important to control the proportion of oriented grains and the average crystal grain size. In addition, it has been clarified that when these are controlled, it is preferable to optimize the grain size after hot rolling and the reduction rate during cold rolling. Specifically, it is clarified that it is preferable to take into account the chemical composition of the α-γ phase transformation system that ensures hot workability and suppresses alloy costs by suppressing the addition of austenite stabilizing elements such as Mn to a minimum, induce γ→α phase transformation during hot rolling, and perform rolling under specified conditions before and after the phase transformation to optimize the grain size, and then perform cold rolling at a specified reduction rate, control the temperature of intermediate annealing within a specified range, and further perform annealing after performing skin smooth rolling (second cold rolling) at an appropriate reduction rate, thereby making the usually difficult-to-develop {411} <011> Oriented grains are more likely to develop. Based on this knowledge, the present inventors have conducted further intensive studies and, as a result, have come up with various aspects disclosed below.

[0039] [1] A non-oriented electrical steel sheet according to one embodiment of the present disclosure has the following chemical composition: in terms of mass%, it contains C: 0.0100% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: a total of 0% to 0.010%, whereby the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content, and P content are expressed as [P] in mass%, 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.

[0040] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])…(1),

[0041] When {hkl} is measured by SEM-EBSD on a surface parallel to the rolled surface at a depth of 1 / 2 the thickness of the steel plate from the surface, <uvw>When the area ratio of oriented grains to the total field of view is recorded as Ahkl-uvw, A411-011 is 15.0% or more. In the ODF, Φ=20° has the maximum strength at The maximum strength is achieved at Φ=5~35° in the range of Φ=0~90°.

[0042] The average crystal grain size is 50 μm to 150 μm.

[0043] [2] In the non-oriented electrical steel sheet according to [1], the area ratio of grains of a specific orientation relative to the total field of view when measured by the SEM-EB SD on a surface parallel to the rolling surface at a depth of 1 / 2 the thickness from the surface of the steel sheet may satisfy both the following equations (2) and (3):

[0044] A411-011 / A411-148≧1.1…(2),

[0045] A411-011 / A100-011≧2.0…(3).

[0046] [3] In the non-oriented electrical steel sheet described in [1] or [2] above, one or more selected from Mn, Ni, Co, Pt, Pb, Au and Cu may be less than 2.50% in total.

[0047] [4] In another embodiment of the present disclosure, the base sheet of the non-oriented electrical steel sheet has the following chemical composition: in terms of mass%, C: 0.0100% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: a total of 0% to 0.010%, whereby the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content, and P content are expressed as [P] in mass%, 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.

[0048] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])…(1),

[0049] The area ratio A of the grains with α-fiber crystal orientation relative to the total field of view when measured by SEM-EBSD on a surface parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the steel plate surface sα More than 20.0%,

[0050] {100} when measuring and preparing ODF using the above-mentioned SEM-EBSD <011> The ODF strength of the orientation is 15.0 or less,

[0051] When the number average of GOS with respect to the total field of view when measured by the SEM-EBSD is expressed as Gs, the Gs is 0.8 or more and 3.0 or less.

[0052] [5] An iron core according to another embodiment of the present disclosure includes the non-oriented electromagnetic steel sheet according to any one of [1] to [3].

[0053] [6] Another embodiment of the present disclosure provides an iron core comprising the original non-oriented electromagnetic steel sheet as described in [4].

[0054] [7] Another embodiment of the present disclosure is a cold-rolled steel sheet for use in manufacturing the non-oriented electrical steel sheet according to any one of [1] to [3] or the base sheet of the non-oriented electrical steel sheet according to [4].

[0055] The invention has the following chemical composition: containing, in mass%, C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and At least one selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total, where, in percentage by mass, the C content is represented by [C], the Mo content is represented by [Mo], the Cr content is represented by [Cr], the Mn content is represented by [Mn], the Ni content is represented by [Ni], the Cu content is represented by [Cu], the Si content is represented by [Si], the sol.Al content is represented by [sol.Al], and the P content is represented by [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] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])…(1),

[0057] The area ratio A of the grains with α-fiber crystal orientation relative to the total field of view when measured by SEM-EBSD on a surface parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the steel plate surface aα It is more than 15.0%.

[0058] [8] Another embodiment of the present invention discloses a method for manufacturing a non-oriented electrical steel sheet, comprising the following manufacturing steps: a hot rolling step of hot-rolling a steel material to obtain a hot-rolled steel sheet, wherein the steel material has the following chemical composition: in mass %, containing C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, one or more selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.4 0%, Sb: 0% to 0.40%, P: 0% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: a total of 0% to 0.010%, whereby the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content and P content are expressed as [P] in mass%, 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.

[0059] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])…(1);

[0060] a cooling step of cooling the hot-rolled steel sheet after the hot rolling step;

[0061] a cold rolling step of cold-rolling the hot-rolled steel sheet after the cooling step to obtain a cold-rolled steel sheet;

[0062] An intermediate annealing step of performing intermediate annealing on the cold-rolled steel sheet;

[0063] a skin-pass rolling step of skin-pass rolling the cold-rolled steel sheet after the intermediate annealing step to obtain a base sheet of a non-oriented electrical steel sheet; and

[0064] a final annealing step of performing final annealing on the base sheet of the non-oriented electrical steel sheet after the skin pass rolling step;

[0065] In the hot rolling step, rolling is performed in such a manner that the starting temperature of rolling exceeds the Ar3 temperature + 20°C, the finishing temperature of rolling is lower than the Ar3 temperature, the rolling reduction rate during the period from the completion of rolling to the time when the rolling first passes through the Ar3 temperature is 15% or more, and the rolling reduction rate during the period from the time when the rolling first passes through the Ar3 temperature to the time when the rolling first passes through the Ar3 temperature + 20°C is 10% or more,

[0066] In the cooling step, cooling is started after 0.10 seconds or more from the final pass of the finishing rolling, and the Ar3 temperature is set to 300°C or higher and -20°C or lower after 3 seconds.

[0067] The reduction rate in the skin-pass rolling process is set to 5 to 20%.

[0068] In the final annealing step, the annealing temperature is set to 750° C. or higher and 900° C. or lower, and the annealing time is set to 2 hours or longer.

[0069] [9] In another embodiment of the present disclosure, a method for manufacturing a base plate of a non-oriented electrical steel sheet comprises the following manufacturing steps: a hot rolling step of hot-rolling a steel material to obtain a hot-rolled steel plate, wherein the steel material has the following chemical composition: in terms of mass%, C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, one or more selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: a total of 0% to 0.010%, whereby the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content and P content are expressed as [P] in mass %, 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.

[0070] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])…(1);

[0071] a cooling step of cooling the hot-rolled steel sheet after the hot rolling step;

[0072] a cold rolling step of cold-rolling the hot-rolled steel sheet after the cooling step to obtain a cold-rolled steel sheet;

[0073] an intermediate annealing step of performing intermediate annealing on the cold-rolled steel sheet; and

[0074] a skin-pass rolling step of skin-pass rolling the cold-rolled steel sheet after the intermediate annealing step to obtain a base sheet of a non-oriented electrical steel sheet;

[0075] In the hot rolling step, rolling is performed in such a manner that the starting temperature of rolling exceeds the Ar3 temperature + 20°C, the finishing temperature of rolling is lower than the Ar3 temperature, the rolling reduction rate during the period from the completion of rolling to the time when the rolling first passes through the Ar3 temperature is 15% or more, and the rolling reduction rate during the period from the time when the rolling first passes through the Ar3 temperature to the time when the rolling first passes through the Ar3 temperature + 20°C is 10% or more,

[0076] In the cooling step, cooling is started after 0.10 seconds or more from the final pass of the finishing rolling, and the Ar3 temperature is set to 300°C or higher and -20°C or lower after 3 seconds.

[0077] The reduction ratio in the skin pass rolling step is set to 5 to 20%.

[0078]

[10] In the method for manufacturing the non-oriented electrical steel sheet described in [8] or the original sheet of the non-oriented electrical steel sheet described in [9], in the cooling step, the average crystal grain size of the hot-rolled steel sheet after the cooling step can also be set to 3 to 10 μm.

[0079]

[11] In the method for producing the non-oriented electrical steel sheet described in [8] or the raw sheet of the non-oriented electrical steel sheet described in [9], the reduction ratio in the cold rolling step may be 75 to 95%.

[0080]

[12] In the method for producing the non-oriented electrical steel sheet described in [8] or the raw sheet of the non-oriented electrical steel sheet described in [9], the annealing temperature may be set to 900° C. or lower in the intermediate annealing step.

[0081]

[13] In another embodiment of the present disclosure, a method for manufacturing a cold-rolled steel sheet includes the following manufacturing steps: a hot rolling step of hot-rolling a steel material to obtain a hot-rolled steel sheet, wherein the steel material has the following chemical composition: in terms of mass%, C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, one or more selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40 %, Sb: 0% to 0.40%, P: 0% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: a total of 0% to 0.010%, whereby the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content and P content are expressed as [P] in mass %, 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.

[0082] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])…(1);

[0083] a cooling step of cooling the hot-rolled steel sheet after the hot rolling step;

[0084] a cold rolling step of cold-rolling the hot-rolled steel sheet after the cooling step to obtain a cold-rolled steel sheet; and

[0085] An intermediate annealing step is performed on the cold-rolled steel sheet.

[0086] In the hot rolling step, rolling is performed in such a manner that the starting temperature of rolling exceeds the Ar3 temperature + 20°C, the finishing temperature of rolling is lower than the Ar3 temperature, the rolling reduction rate during the period from the completion of rolling to the time when the rolling first passes through the Ar3 temperature is 15% or more, and the rolling reduction rate during the period from the time when the rolling first passes through the Ar3 temperature to the time when the rolling first passes through the Ar3 temperature + 20°C is 10% or more,

[0087] In the cooling step, cooling is started after 0.10 seconds or more have passed since the final pass of finish rolling, and the temperature is set to 300° C. or higher and Ar3 temperature -20° C. or lower after 3 seconds.

[0088]

[14] In the method for manufacturing a cold-rolled steel sheet as described in

[12] above, in the cooling step, the average crystal grain size of the hot-rolled steel sheet after the cooling step may be set to 3 to 10 μm.

[0089]

[15] In the method for manufacturing a cold-rolled steel sheet as described in

[12] or

[13] above, the reduction ratio in the cold rolling step may be 75 to 95%.

[0090]

[16] In the method for producing a cold-rolled steel sheet as described in

[12] or

[13] above, the annealing temperature may be set to 900° C. or less in the intermediate annealing step.

[0091] Effects of the Invention

[0092] According to the above-described aspects of the present disclosure, it is possible to provide a non-oriented electromagnetic steel sheet having low stress sensitivity, particularly a low iron loss degradation rate due to stress, and excellent magnetic properties in the 45° direction; an iron core using the non-oriented electromagnetic steel sheet; a base sheet of the non-oriented electromagnetic steel sheet for producing the non-oriented electromagnetic steel sheet; a cold-rolled steel sheet; a method for producing a non-oriented electromagnetic steel sheet; a method for producing a base sheet of the non-oriented electromagnetic steel sheet; and a method for producing a cold-rolled steel sheet. DETAILED DESCRIPTION

[0093] Hereinafter, a non-oriented electromagnetic steel sheet according to an embodiment of the present disclosure (the non-oriented electromagnetic steel sheet of the present embodiment), a base sheet of the non-oriented electromagnetic steel sheet (the base sheet of the non-oriented electromagnetic steel sheet of the present embodiment), a cold-rolled steel sheet (the cold-rolled steel sheet of the present embodiment), and methods for manufacturing the same will be described in detail.

[0094] First, the chemical composition of the non-oriented electrical steel sheet of this embodiment and the steel material used for its production (which serves as the raw material) will be described. In the following description, "%" as a unit of the content of each element contained in the non-oriented electrical steel sheet or steel material means "mass %" unless otherwise specified. In addition, the numerical range expressed using "to" means a range that includes the numerical values described before and after "to" as the lower limit and upper limit. In addition, of course, the various elements of the following embodiments can be combined individually. In addition, the chemical composition of the non-oriented electrical steel sheet represents the content when the base material excluding the coating, etc. is regarded as 100%.

[0095] Furthermore, within the numerical ranges described in stages in this specification, the upper limit value of a numerical range at 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 described in the Examples.

[0096] In the numerical ranges described in stages in this specification, the lower limit value of a numerical range in a certain stage may be replaced by the lower limit value of a numerical range described in another stage, or may be replaced by a value described in Examples.

[0097] In this specification, the terms "non-oriented electromagnetic steel sheet" and "original plate of non-oriented electromagnetic steel sheet" include steel sheets in coil or cut sheet form, as well as steel sheets and original plates processed into specific shapes as raw materials for products (components) such as motor cores, and steel sheets and original plates that are stacked after processing to form motor cores.

[0098] The non-oriented electrical steel sheet, the raw sheet of the non-oriented electrical steel sheet, and the cold-rolled steel sheet of the present embodiment have a chemical composition capable of causing a ferrite-austenite transformation (hereinafter referred to as α-γ transformation) to a certain extent (even if the entire steel sheet is not transformed into γ, a certain amount of γ is generated when heated), and the chemical composition contains: C: 0.0100% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2% in total 0.5%, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: a total of 0% to 0.010%. Furthermore, the contents of C, Si, P, sol. Al, Mn, Mo, Cu, Cr, and Ni satisfy the specified conditions described below, with the remainder consisting of Fe and impurities. Examples of impurities include impurities contained in raw materials such as ores and scrap, and impurities contained during the manufacturing process.

[0099] Furthermore, the non-oriented electrical steel sheet, the raw sheet of the non-oriented electrical steel sheet, and the cold-rolled steel sheet of the present embodiment preferably contain less than 2.50% in total of one or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu.

[0100] (C: 0.0100% or less)

[0101] C is an element that inhibits grain growth due to the precipitation of fine carbides, thereby increasing iron loss and causing 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 0.0100% or less. The C content is preferably 0.0050% or less, and more preferably 0.0025% or less. The lower limit of the C content is not particularly limited, but based on the cost of decarburization treatment during refining, the C content is preferably 0.0005% or more.

[0102] (Si: 1.50% to 4.00%)

[0103] Si is an element that increases electrical resistance, reduces eddy current loss, lowers iron loss, increases yield ratio, and improves punchability into the core. These effects are not fully achieved when the Si content is less than 1.50%. Therefore, the Si content should be 1.50% or more.

[0104] On the other hand, when the Si content exceeds 4.00%, the magnetic flux density decreases or the hardness increases excessively, resulting in a decrease in blanking workability and difficulty in cold rolling. Therefore, the Si content is set to 4.00% or less.

[0105] (sol.Al: 0.0001% to 1.00%)

[0106] Sol-Al increases electrical resistance, reduces eddy current loss, and lowers iron loss. Sol-Al also helps increase the magnetic flux density (B50) relative to the saturation magnetic flux density. Here, magnetic flux density (B50) refers to the magnetic flux density at a magnetic field of 5000 A / m. These effects cannot be fully achieved when the sol-Al content is less than 0.0001%. Furthermore, Al also promotes desulfurization during steelmaking. Therefore, the sol-Al content is set to 0.0001% or higher.

[0107] On the other hand, if the sol.Al content exceeds 1.00%, the magnetic flux density decreases. Therefore, the sol.Al content is set to 1.00% or less.

[0108] In addition, the so-called sol.Al refers to acid-soluble Al that is soluble in acid without becoming an oxide such as Al2O3.

[0109] (S: 0.0100% or less)

[0110] S is not an essential element and is contained in steel as an impurity, for example. S precipitates as fine MnS, which hinders recrystallization and grain growth during annealing. Therefore, the lower the S content, the better. The increase in iron loss and the decrease in magnetic flux density caused by the hindrance of recrystallization and grain growth are significant when the S content exceeds 0.0100%. Therefore, the S content is 0.0100% or less. There is no particular lower limit for the S content, but based on the cost of desulfurization treatment during refining, the S content is preferably 0.0003% or more.

[0111] (N: 0.0100% or less)

[0112] Nitrogen degrades magnetic properties by forming fine precipitates such as TiN and AlN. Therefore, the lower the N content, the better. This deterioration in magnetic properties becomes significant when the N content exceeds 0.0100%, so the N content should be 0.0100% or less. While there is no specific lower limit for the N content, it is preferably 0.0010% or more based on the cost of denitrification during refining.

[0113] (One or more selected from the group consisting of Mn, Ni, and Cu: less than 2.50% in total)

[0114] These elements are effective for causing α-γ transformation, but on the other hand, they reduce workability during hot rolling and increase alloy costs. Therefore, the content of these elements needs to be limited to less than 2.5% in total.

[0115] Furthermore, if the total content exceeds 2.5%, the magnetic flux density may also decrease. On the other hand, since these elements are effective in reducing iron loss, a total content of 1.5% or more is preferably used. Ni, in particular, is known to improve the reduction in hot brittleness caused by Cu. Within a range where the total content of one or more selected from Mn, Ni, and Cu is less than 2.50%, it is preferable to contain Ni in an amount of approximately 1 / 2 the Cu content or less in terms of hot brittleness.

[0116] Furthermore, Mn lowers the Ar3 transformation point, and in the composition system of the non-oriented electrical steel sheet of this embodiment, it is possible to achieve grain refinement of the hot-rolled sheet due to phase transformation. Mn is an element that increases the electrical resistance of steel and reduces iron loss. Therefore, it is preferable to contain 0.10% or more of Mn. From this point of view, it is more preferable to contain 0.50% or more of Mn. Even more preferably, it is 1.00% or more. On the other hand, Mn is an element that easily segregates. If its content increases, it not only causes cold working cracks due to segregation, but also reduces the saturation magnetic flux density, hindering the increase in the magnetic flux density of the steel sheet. In addition, excessive generation of MnS reduces cold workability. Therefore, the upper limit of the Mn content is limited to less than 2.5%. Specifically, the upper limit of the Mn content is preferably 2.3% by mass or less, and more preferably 2.0% by mass or less.

[0117] The upper limit of the Cu content is not particularly limited, but is preferably 1.5% by mass or less, more preferably 1.0% by mass or less. The lower limit of the Cu content is not particularly limited, and may be, for example, 0.01% or more. The upper limit of the Ni content is preferably 1.0% by mass or less, more preferably 0.7% by mass or less. The lower limit of the Ni content is not particularly limited, and may be 0%, for example, 0.01% or more.

[0118] The total content of one or more selected from Mn, Ni, and Cu is preferably 2.45% or less, more preferably 2.40% or less. The lower limit of the total content of Mn, Ni, and Cu is not particularly limited, and may be, for example, 0.10% or more, 0.50% or more, or 1.00% or more, or further 2.00% or more.

[0119] (One or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu: less than 2.50% in total)

[0120] In addition to the above-mentioned Mn, Ni, and Cu, Co, Pt, Pb, and Au reduce the workability during hot rolling and increase the alloy cost, so in this embodiment, the content of these elements is preferably limited to less than 2.5% in total. In addition, since these elements reduce the magnetic flux density, it is preferably less than 2.00% in total. There is no particular restriction on the lower limit of the total of Mn, Ni, Co, Pt, Pb, Au, and Cu. For example, it can be more than 0.10%, more than 0.50%, or more than 1.00%, or even 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, considering the control of the Ar3 transformation point, which is one of the characteristics of this embodiment, it is also preferred to control the Ar3 transformation point by containing Mn, Ni, and Cu. Therefore, the total of Co, Pt, Pb, and Au is less than 0.5%, more preferably less than 0.1%, and is further limited to the mixing within the range of unavoidable elements, and there is no need to implement active addition (it can also be 0%).

[0121] In addition, as a condition for generating α-γ phase transformation and obtaining good magnetic properties, it is preferable to further satisfy the following condition. That is, when the C content in mass % is expressed as [C], the Mo content is expressed as [Mo], the Cr content is expressed as [Cr], the Mn content is expressed as [Mn], the Ni content is expressed as [Ni], the Cu content is expressed as [Cu], the Si content is expressed as [Si], the sol.Al content is expressed as [sol.Al], and the P content is expressed as [P], the phase transformation temperature Ar3 (°C) determined by the following formula (1) satisfies 750 to 1050°C,

[0122] Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni])…(1).

[0123] 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. Therefore, even if the manufacturing method described below is applied, a sufficient magnetic flux density cannot be obtained. If Ar3 is less than 750°C, the deformation resistance increases due to the low temperature of hot rolling, the load on the rolling mill becomes too large, and the amount of element addition increases, which also leads to a decrease in the toughness of the hot-rolled and cold-rolled sheets. Therefore, this value is set as the lower limit. On the other hand, if Ar3 exceeds 1050°C, the hot rolling temperature becomes too high, so extremely high-temperature heating is required, the load on the heating furnace increases, or the composition system does not produce the γ→α phase transformation. Therefore, this value is set as the upper limit.

[0124] (Mo: 0.0%~less than 2.5%)

[0125] Mo is an element that lowers the Ar3 transformation point and, in the chemical composition of the non-oriented electrical steel sheet of this embodiment, enables miniaturization of the hot-rolled sheet grain size due to phase transformation. Therefore, Mo may be contained as needed, preferably at a content of 0.1% or more. On the other hand, since a Mo content of 2.5% or more significantly reduces cold workability, the Mo content is set to less than 2.5%.

[0126] (Cr: 0.0% to less than 2.5%)

[0127] Cr is an element that lowers the Ar3 transformation point, enabling the refinement of the hot-rolled sheet grain size through phase transformation in the chemical composition of the non-oriented electrical steel sheet of this embodiment. In addition to improving strength and corrosion resistance, it also has the effect of enhancing high-frequency characteristics. Therefore, Cr may be included as needed, preferably at a content of 0.1% or more. However, excessive Cr content not only saturates the effect and increases raw material costs, but also reduces the saturation magnetic flux density, hindering an increase in the magnetic flux density of the steel sheet. Therefore, the Cr content is set to less than 2.5%.

[0128] (Ti: 0% to 0.005%)

[0129] Ti inhibits recrystallization by dissolving or existing as TiN, contributing to the refinement of austenite grain size. Therefore, Ti may be contained. When Ti is contained, it is preferably contained 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 kept below 0.005%.

[0130] (Nb: 0% to 0.005%)

[0131] Nb inhibits recrystallization by dissolving it in solid or existing as NbN, contributing to the refinement of austenite grain size. Therefore, Nb may be contained. When Nb is contained, it is preferably contained 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 Nb content is kept below 0.005%.

[0132] (Sn: 0% to 0.40%, Sb: 0% to 0.40%)

[0133] Sn and Sb improve the texture after cold rolling and recrystallization, increasing magnetic flux density. Therefore, these elements may be included as needed. To achieve further effects on magnetic properties, it is preferred to include one or more selected from the group consisting of 0.02% to 0.40% Sn and 0.02% to 0.40% Sb.

[0134] On the other hand, excessive inclusion of these elements will make the steel brittle. Therefore, the Sn content and the Sb content are both 0.40% or less.

[0135] (P: 0% to 0.400%)

[0136] P is an element that is effective in ensuring the hardness of the steel sheet after recrystallization. Furthermore, P also has a favorable effect on magnetic properties. Therefore, P may be contained. To achieve these effects, the P content is preferably set to 0.020% or more.

[0137] On the other hand, if excessive P is contained, the steel becomes brittle. Therefore, the P content is set to 0.400% or less.

[0138] (One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total)

[0139] Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd react with sulfur in 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 hinder recrystallization and grain growth during annealing processes such as intermediate annealing. To fully achieve these effects, the total content of these elements is preferably 0.0005% or more, and more preferably 0.001% or more.

[0140] On the other hand, if the total content of these elements exceeds 0.010%, sulfides or oxysulfides, or the total amount of both, become excessive, hindering recrystallization and grain growth during annealing such as intermediate annealing. Therefore, the total content of coarse precipitate-forming elements is set to 0.010% or less.

[0141] In this embodiment, the remainder of the chemical composition other than that 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 some of the Fe, as long as the effects of the present disclosure are not diminished. For example, each of B, O, V, Bi, W, and Y may be included at a level of 0.10% or less. Furthermore, the total impurity content is preferably 5.00% or less, and more preferably 1.00% or less.

[0142] The chemical composition was determined by the following method.

[0143] The chemical composition can be measured using standard steel analysis methods. For example, the chemical composition can be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Specifically, the chemical composition is determined by measuring a test piece collected from the steel plate using a specified measuring device under conditions based on a pre-created calibration curve. C and S can be measured using the combustion-infrared absorption method, N using the inert gas fusion-thermal conductivity method, and O using the inert gas fusion-non-dispersive infrared absorption method.

[0144] When an insulating film is present on the surface, it may be subjected to analysis after being mechanically removed by a grinder or the like.

[0145] Next, the texture of the non-oriented electrical steel sheet according to the present embodiment will be described.

[0146] First, the method for measuring the area ratio of specific orientation grains in the non-oriented electrical steel sheet of this embodiment will be described. The area ratio of specific orientation grains is determined using OIM Analysis 7.3 (manufactured by TSL). The target specific orientation (with a tolerance of 10°, hereinafter referred to as "within 10°") is extracted from the measurement area of a scanning electron microscope (SEM) with electron backscatter diffraction (EBSD) observed under the following measurement conditions. The extracted area is divided by the area of the measurement area to calculate a percentage. This percentage is referred to as the area ratio of specific orientation grains. Hereinafter, the crystal orientation is described as within a tolerance of 10°. In other words, the crystal orientation is assumed to have a tolerance of ±5°.

[0147] The details of the measurement conditions for obtaining the area ratio of each oriented grain are as follows.

[0148] Measurement equipment: SEM model "JSM-6400 (manufactured by JEOL)" and EBSD detector model "HIKARI (manufactured by TSL)" were used.

[0149] Step interval: 0.3μm (after intermediate annealing and skin-pass rolling) or 5.0μm (after final annealing)

[0150] · Magnification: 1000 times (after intermediate annealing and skin-pass rolling) or 100 times (after final annealing)

[0151] ·Measurement object: The surface parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the surface

[0152] Measurement area: Rectangular area of 1000 μm or more × 1000 μm or more

[0153] In the non-oriented electrical steel sheet of the present embodiment, when the surface of the steel sheet (when the surface has an insulating film, the surface of the steel sheet with the insulating film removed, the same applies hereinafter) is measured using a scanning electron microscope with electron backscatter diffraction (SEM-EBSD) according to the above-mentioned method, {411} <011> Rate (to {hkl} <uvw>The area ratio of the oriented grains (within a tolerance of 10°) relative to the total field of view (A411-011 when Ahkl-uvw) is set to 15.0% or more. <011> If the ratio is less than 15.0%, excellent magnetic properties cannot be obtained. <011> The rate is 15.0% or more, preferably 25% or more. The upper limit is not particularly limited, but is, for example, 60% or less.

[0154] In addition, in the non-oriented electrical steel sheet of the present embodiment, when the surface is measured by SEM-EBSD, In the ODF, Φ=20° has the maximum strength at The maximum strength is achieved at Φ = 5 to 35 degrees among Φ = 0 to 90 degrees.

[0155] exist Φ=20° has the maximum intensity at {411} <uvw>Orientation in {411} <011> The orientation having the maximum intensity near it is synonymous. {411} <011> Orientation and {411} <148> etc. {411} <uvw>Compared with other orientations in the orientation, the magnetic properties in the 45° direction are excellent. Φ=20° Has maximum strength.

[0156] On the other hand, when the surface is measured by SEM-EBSD, The maximum intensity is at Φ = 5 to 35 degrees in the range of Φ = 0 to 90 degrees. <011> Orientation in {411} <011> The orientation having the maximum intensity near it is synonymous. {411} <011> The magnetic properties of the orientation are excellent and are similar to {100} <011> etc. <011> The stress sensitivity of the orientation is lower than that of the other orientations, so the magnetic deterioration caused by the stress generated by the riveted core is less. The maximum strength is achieved at Φ = 20 to 30 degrees among Φ = 0 to 90 degrees.

[0157] The following describes the method for determining the maximum strength within a specific orientation range and the strength in a specific orientation (ODF strength) in a steel plate. In the measurement area of SEM-EBSD, OMI Analysis 7.3 was used to create an orientation distribution function (ODF) under the following conditions. The created ODF data was then output and the strength in a specific orientation range (in The point where the ODF value (ODF value) is the maximum within the specified range of the angle of Φ is taken as the maximum intensity. The ODF value (ODF value) of the orientation (the angle Φ specifies the orientation) is taken as the ODF intensity of the orientation.

[0158] The details of the ODF production conditions are as follows.

[0159] Series Rank (L): 16

[0160] Gaussian Half-Width [degrees]: 5

[0161] Sample Symmetry: Orthotropic (Rolled sheet)

[0162] (Anisotropy (rolled plate))

[0163] Bunge Euler Angles: Φ=0~90°

[0164] Furthermore, in the non-oriented electrical steel sheet of the present embodiment, the area ratio of grains having a specific orientation (within a tolerance of 10°) relative to the total field of view (entire field of view) when measured by SEM-EBSD preferably satisfies both the following formulas (2) and (3):

[0165] A411-011 / A411-148≧1.1…(2),

[0166] A411-011 / A100-011≧2.0…(3).

[0167] Regarding formula (2), {411} <011> Orientation and {411} <148> etc. {411} <uvw>Compared with other orientations, the 45° direction has excellent magnetic properties. Therefore, {411} <011> Rate exceeds {411} <148> rate, more preferably {411} <011> The rate is {411} <011> The upper limit of the ratio of A411-011 to A411-148 is not limited, but is set to 50 or less, for example.

[0168] In addition, regarding formula (3), since the stress sensitivity of magnetic properties is {411} <011> Orientation ratio {100} <011> Orientation is low, so {411} is preferred <011> Rate exceeds {100} <011> rate, more preferably {411} <011> The rate is {100} <011> The upper limit of the ratio of A100-011 to A411-011 is not limited, and is, for example, 50 or less.

[0169] Next, the average crystal grain size of the non-oriented electromagnetic steel sheet of the present embodiment is described. If the grains are not coarsened and the average crystal grain size is too small, the iron loss deteriorates. On the other hand, if the grains are excessively coarsened and the average crystal grain size is too large, not only the workability deteriorates, but also the eddy current loss deteriorates. Therefore, the average crystal grain size of the non-oriented electromagnetic steel sheet is set to 50μm to 150μm. The method for measuring the grain size is, for example, to measure it in a plane parallel to the rolling surface at a depth of 1 / 2 of the plate thickness from the steel plate surface using the cutting method of JIS G0551 (2020).

[0170] 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 not particularly limited. The preferred thickness of the non-oriented electromagnetic steel sheet of the present embodiment is 0.10 to 0.50 mm. Generally, if the plate thickness becomes thinner, the iron loss decreases, but the magnetic flux density decreases. Based on this, if the plate thickness is 0.10 mm or more, the iron loss is further reduced and the magnetic flux density is further increased. A more preferred lower limit value of the plate thickness is 0.12 mm, and a further preferred lower limit value is 0.14 mm. In addition, if the plate thickness is 0.50 mm or less, low iron loss can be maintained. A more preferred upper limit value of the plate thickness is 0.35 mm, and a further preferred upper limit value is 0.25 mm.

[0171] The above-mentioned non-oriented electrical steel sheet is characterized in that it is manufactured by performing hot rolling, cooling, cold rolling, intermediate annealing, skin pass rolling, and final annealing, which will be described later.

[0172] Next, the characteristics of the base non-oriented electrical steel sheet before final annealing (after skin pass rolling) will be described.

[0173] The original non-oriented electrical steel sheet of this embodiment after skin-pass rolling and before final annealing has the following GOS (Grain Orientation Spread) values. The GOS (hereinafter referred to as the "GOS" value) relative to the entire field of view when measured using SEM-EBSD is the average of the orientation differences between all measurement points (pixels) within the same grain. The GOS value is higher in grains with high strain. After skin-pass rolling, if the GOS value is low, i.e., the strain state is low, then grain growth due to expansion is more likely to occur during the final annealing step in the next step. Therefore, the number average GOS value Gs after skin-pass rolling is set to 3.0 or less.

[0174] On the other hand, if the number average Gs of the GOS values is less than 0.8, the strain amount is too small, and the final annealing time required for grain growth due to expansion becomes long.

[0175] Therefore, the number average Gs of the GOS values after skin pass rolling is set to 0.8 or more and 3.0 or less.

[0176] The calculation method of Gs is described.

[0177] The SEM-EBSD data obtained when the crystal orientation was specified as described above were analyzed using OIM Analysis 7.3 to determine the number average of the GOS values, which was used as Gs.

[0178] When calculating the GOS value, it is necessary to define the grain size (grain size), which is detailed below.

[0179] Grain Tolerance Angle: 5°

[0180] Minimum Grain Size: 2

[0181] Minimum Conficence Index: 0

[0182] The number average Gs of the GOS values of each grain determined based on this definition is obtained. In OIM Analysis 7.3, the GOS histogram can be obtained using the Chart function, and the number average can be obtained at the same time (marked as Number in the software).

[0183] In addition, in the original sheet of the non-oriented electrical steel sheet after skin temper rolling (before final annealing), the area ratio A of the grains having α-fiber crystal orientation relative to the total field of view when measured by SEM-EBSD is sα (hereinafter also referred to as "α fiber ratio"), the greater the magnetic properties after the final annealing are. Therefore, in the raw sheet of the non-oriented electrical steel sheet after skin pass rolling (before final annealing) of this embodiment, the α fiber ratio (A sα ) is 20.0% or more. sα It is preferably 25.0% or more. sα The upper limit of ) is not particularly limited, but is, for example, 70% or less. sα ) may be 25.0% or more, preferably 30.0% or more.

[0184] In this embodiment, the α fiber is {hkl} <011> orientation.

[0185] The method for measuring the α-fiber ratio will be described.

[0186] In the SEM-EBSD measurement area at a depth of 1 / 2 the plate thickness from the surface, {hkl} was extracted using OIM Analysis 7.3. <011> Orientation (within a tolerance of 10°). Divide the extracted area by the area of the measurement region to calculate the percentage. This percentage is referred to as the α-fiber ratio. The SEM-EBSD measurement area (i.e., the total field of view) is a cross-section through the plate thickness at the center of the plate width, measuring at least 1000 μm x 1000 μm. The SEM-EBSD measurement conditions are the same as those described for determining the area ratio of oriented grains above.

[0187] In addition, in the original sheet of the non-oriented electrical steel sheet after skin temper rolling and before final annealing according to the present embodiment, the {100} <011> The ODF intensity of the orientation is 15.0 or less. Here, {100} <011> The ODF intensity of the orientation is the intensity of the ODF produced using SEM-EBSD data when specifying the above crystal orientation. ODF value at Φ = 0°. <011> The orientation is excellent in magnetic properties and is similar to {100} <011> Oriented phases are less sensitive to stress and therefore have less magnetic degradation in riveted cores, etc. By making the {100} <011> The ODF strength of the orientation is 15.0 or less, which can strengthen the {411} <011> Orientation. {100} <011> The lower limit of the oriented ODF intensity is not particularly limited, and is, for example, -0.1.

[0188] The same method as that for the above non-oriented electrical steel sheet was used to determine the {100} <011> Orientation represents the ODF intensity of a specific orientation.

[0189] The non-oriented electrical steel sheet of the present embodiment can be widely used in applications requiring magnetic properties (high magnetic flux density and low iron loss) by forming the iron core. Applications of the iron core are, for example, as follows.

[0190] (A) Servo motors, stepper motors, and compressors used in motor equipment

[0191] (B) Drive motors for electric vehicles and hybrid vehicles. Vehicles include automobiles, motorcycles, and railways.

[0192] (C) Generator

[0193] (D) Iron cores, choke coils, and reactors for various purposes

[0194] (E) Current sensor, etc.

[0195] The non-oriented electrical steel sheet of this embodiment can also be used in applications other than those described above. The non-oriented electrical steel sheet of this embodiment is particularly suitable for use as a split core designed so that the main magnetization direction of the core is the direction at a 45-degree angle to the rolling direction of the steel sheet. Furthermore, it is suitable for use in split cores for drive motors of electric vehicles or hybrid vehicles operating in high-frequency regions of 1000 Hz or higher.

[0196] It should be noted that the aforementioned industrial advantages can be achieved not only by punching and laminating the non-oriented electromagnetic steel sheets of this embodiment to form an iron core, but also by punching and laminating the raw sheets of the non-oriented electromagnetic steel sheets of this embodiment to form an iron core, followed by appropriate heat treatment. Therefore, in this disclosure, both the iron core formed by laminating the non-oriented electromagnetic steel sheets of this embodiment and the iron core formed by laminating the raw sheets of the non-oriented electromagnetic steel sheets of this embodiment are the subject of this disclosure.

[0197] These are simply differences in the timing of the "final annealing" (described later) within the production process, whether it is performed on the steel sheet before core formation or after core formation. In either case, appropriate effects can be achieved. Details on the timing of "final annealing" will be discussed later.

[0198] Furthermore, a core formed by laminating raw sheets of the non-oriented electrical steel sheets of this embodiment can be used without final annealing. While this method may not yield particularly good magnetic properties, the strain caused by skin-pass rolling is accumulated, resulting in higher resistance. Therefore, it is considered a suitable application for rotor cores, which prioritize suppressing deformation caused by centrifugal forces associated with high-speed rotation over magnetic properties.

[0199] Next, the cold-rolled steel sheet according to the present embodiment will be described.

[0200] The cold-rolled steel sheet of the present embodiment is a cold-rolled steel sheet used for producing the above-mentioned non-oriented electrical steel sheet.

[0201] When a non-oriented electrical steel sheet is produced from a cold-rolled steel sheet, the chemical composition does not substantially change. Therefore, the chemical composition of the cold-rolled steel sheet of the present embodiment is within the same range as that of the non-oriented electrical steel sheet of the present embodiment described above.

[0202] In addition, in the cold-rolled steel sheet of the present embodiment, the area ratio A of the grains having the α-fiber crystal orientation relative to the total field of view when measured by SEM-EBSD on a surface parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the steel plate surface is aα It is more than 15.0%.

[0203] In A aα When the α fiber ratio (A sα ) does not exceed 20.0%, and {411} after final annealing <011> The rate does not exceed 15.0%.

[0204] The area ratio A of the grains with α-fiber crystal orientation aα The upper limit of is not particularly limited, but is set to 70% or less, for example. aα The lower limit of % may be 20.0% or more, and preferably 25.0% or more.

[0205] In addition, the method for measuring the crystal orientation is the same as that of the above-mentioned non-oriented electrical steel sheet.

[0206] Next, an example of a method for manufacturing a non-oriented electrical steel sheet, a base sheet of a non-oriented electrical steel sheet, and a cold-rolled 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 manufacturing method including a hot rolling step, a cooling step, a cold rolling step, an intermediate annealing step, a skin pass rolling step (soft reduction cold rolling step), and a final annealing step.

[0207] Furthermore, through the steps up to the final annealing (hot rolling step, cooling step, cold rolling step, intermediate annealing step, skin pass rolling step), a base sheet of the non-oriented electrical steel sheet of the present embodiment is obtained.

[0208] Furthermore, the cold-rolled steel sheet of the present embodiment is obtained through the steps up to the intermediate annealing (hot rolling step, cooling step, cold rolling step, intermediate annealing step).

[0209] Hereinafter, preferred conditions for each step will be described.

[0210] In addition, the Ar3 temperature is the phase transition temperature Ar3 (° C.) determined by the above-mentioned formula (1).

[0211] (Hot rolling process)

[0212] In the hot rolling process, the steel material satisfying the above chemical composition is hot rolled to obtain a hot-rolled steel sheet. The hot rolling process includes a heating process and a rolling process.

[0213] Steel materials, for example, are slabs produced by conventional continuous casting. Steel materials with the aforementioned chemical composition are produced using known methods. For example, molten steel is produced using a converter or electric furnace. The produced molten steel undergoes secondary refining using degassing equipment, etc., to produce molten steel with the aforementioned chemical composition (the chemical composition remains substantially unchanged in subsequent steps). Molten steel is then used to cast slabs using continuous casting or ingot casting. The cast slabs may also be subjected to bloom rolling.

[0214] 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 holding time at the aforementioned heating temperature within the heating furnace or soaking pit is not particularly limited, but is, for example, 30-200 hours.

[0215] During the rolling process, the steel material, heated in the heating process, is rolled through multiple passes to produce hot-rolled steel sheets. Here, a "pass" refers to the reduction of the steel sheet through a rolling stand equipped with a pair of work rolls. Hot rolling can be performed using, for example, a tandem rolling mill comprised of multiple rolling stands arranged in a row (each with a pair of work rolls), or by reverse rolling with a pair of work rolls. From a productivity perspective, using a tandem rolling mill for multiple rolling passes is preferred.

[0216] The rolling in the rolling process (rough rolling and finish rolling) heats the above-mentioned steel material and performs hot rolling. The steel material is, for example, a slab manufactured by conventional continuous casting. The heating of the slab is set to be above the Ar3 temperature, and is set to a temperature region where the steel structure becomes a γ phase. Hot rolling starts in a temperature region where the steel structure becomes a γ phase (hereinafter, this temperature region is sometimes described as a γ region), and is implemented in the γ region except for the necessary number of passes including the final pass of finish rolling. The necessary number of passes including the final pass are implemented and completed in a temperature region where an α phase exists in the steel structure (hereinafter, this temperature region is sometimes described as an α region). Generally speaking, the front to middle sections of rough rolling and finish rolling are performed in the γ region, and the rear section of finish rolling is performed in the α region.

[0217] In this embodiment, rolling is carried out as follows: the starting temperature of rolling (i.e., the heating temperature of the steel before rolling) is higher than the Ar3 temperature + 20°C, the finishing temperature of rolling (i.e., the finishing temperature FT) is lower than the Ar3 temperature, the reduction rate during the period from the completion of rolling to the initial passage through the Ar3 temperature (i.e., the total reduction rate in the temperature zone above the finishing temperature FT and below the Ar3 temperature in the final α zone) is greater than 15%, and the reduction rate during the period from the initial passage through the Ar3 temperature to the initial passage through the Ar3 temperature + 20°C (i.e., the total reduction rate in the temperature zone above the Ar3 temperature and below the Ar3 temperature + 20°C before rolling is performed in the final α zone) is greater than 10%.

[0218] Thus, the total reduction ratio in the temperature range of the final α region from Ar3 temperature to Ar3 temperature + 20° C. immediately before rolling is 10% or more. The upper limit of the reduction ratio is not limited, but is, for example, 40% or less.

[0219] Furthermore, the total reduction ratio in the final α region in the temperature range of the finishing rolling temperature FT or higher and lower than the Ar3 temperature is 15% or higher in total, taking into account the case of rolling in multiple passes. The upper limit of this reduction ratio is not limited, and is, for example, 40% or lower.

[0220] Here, the upper limit of the rolling start temperature is not particularly limited, but is set to 1200° C. or lower, for example.

[0221] In addition, the lower limit of the completion temperature of rolling (that is, the finish rolling temperature FT) is not particularly limited, but is, for example, Ar3 temperature - 100°C or higher.

[0222] The rolling start temperature (ie, the heating temperature of the steel material before rolling) refers to the rough rolling start temperature, that is, the surface temperature of the steel material when the steel material is heated before rough rolling.

[0223] The rolling completion temperature (ie, the finishing temperature FT) refers to the surface temperature of the hot-rolled steel sheet immediately after finish rolling.

[0224] In addition, Ar3 temperature and other temperatures indicate the surface temperature of steel or steel plate.

[0225] Rolling in a temperature range exceeding Ar3+20°C before rolling in the final α region has little effect on the size of the processed γ grains before the phase transformation, and coarse processed α grains are formed after the phase transformation, which is closely related to the {411} <011> The lower limit of rolling temperature is Ar3 temperature.

[0226] If the rolling ratio in the temperature range of Ar3 temperature or above and Ar3+20℃ or below before the final α region rolling is less than 10%, the strain accumulation to the processed γ grains before the phase transformation is insufficient, forming coarse processed α grains, which makes it difficult to cause the {411} <011> The rolling reduction rate in the temperature range from Ar3 to Ar3+20°C is preferably 15% or more, more preferably 20% or more. There is no upper limit for the total reduction rate, but if it exceeds 40%, the load on the rolling mill becomes too high, so 40% is preferably used as the upper limit.

[0227] If the rolling ratio in the temperature range above the final finishing rolling temperature FT in the α region and below the Ar3 temperature is less than 15%, the processing strain in the α region cannot be fully accumulated in the processed α grains after the processed γ grains are transformed, making it difficult to induce the {411} <011> The reduction ratio in the temperature range between the finishing temperature FT and below the Ar3 temperature is preferably 20% or more, more preferably 25% or more. There is no upper limit for the reduction ratio, but if it exceeds 40%, the mill load becomes too high, so 40% is preferably the upper limit.

[0228] In the present embodiment, the reduction ratio RR0 in hot rolling is defined as follows.

[0229] Reduction ratio RR0 (%)=(1-plate thickness after rolling in the temperature range of the final pass in hot rolling / plate thickness before rolling in the temperature range of the first pass in hot rolling)×100.

[0230] The lower limit temperature of rolling in the α region is not particularly limited, but if the rolling temperature is lowered, the load on the rolling mill increases, so it is preferably set to 600° C. or higher.

[0231] Furthermore, the rolling temperature may fluctuate around a predetermined determination temperature (Ar3 temperature or Ar3 + 20°C) during the rolling pass, taking into account the competition between the temperature drop caused by roll contact and the cooling lubricant and the temperature rise caused by processing. In this embodiment, such a situation is handled as follows.

[0232] In the rolling pass, the temperature on the entry side is recorded as TPI (℃), the plate thickness on the entry side is recorded as TCI (mm), the temperature on the discharge side is recorded as TPO (℃), and the plate thickness on the discharge side is recorded as TCO (mm). It is further assumed that the plate thickness change and temperature change in the rolling pass change in a state with a simple linear relationship. That is, if the plate thickness at a specific moment in the rolling pass is recorded as TCa (mm) and the temperature is recorded as TPa (℃), then it is assumed that the following formula always holds true in the rolling pass,

[0233] (TCa-TCO) / (TCI-TCO)=(TPa-TPO) / (TPI-TPO).

[0234] 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.

[0235] That is, the plate thickness TCa (mm) at the time when the specific temperature TPa (°C) is reached during the rolling pass can be obtained by the following formula:

[0236] TCa=TCO+(TCI-TCO)×(TPa-TPO) / (TPI-TPO).

[0237] Note that the above assumptions assume that the discharge temperature of a rolling pass is higher than the entry temperature. That is, even if a steel plate with an entry temperature TPI lower than the Ar3 temperature in a particular pass rises in temperature due to working heat within the pass and is discharged at a discharge temperature TPO higher than the Ar3 temperature, rolling in the γ region (a temperature range between Ar3 and Ar3+20°C) required by the present disclosure is determined to have occurred in the latter half of the pass.

[0238] In addition, it is also conceivable that the temperature fluctuations between the Ar3 temperature will occur in multiple passes. In such a case, in this embodiment, the rolling conditions for the α region are based on the "final rolling process in the α region". In addition, the rolling conditions for the γ region are based on the "rolling process in the γ region before the above-mentioned "final rolling process in the α region". That is, the rolling temperature after the start of hot rolling in the γ region is based on the γ region. Even when the configuration is changed, as long as the α region 3 and the γ region 2 meet the conditions of the present embodiment, the steel sheet of the present embodiment can be obtained.

[0239] The rolling temperature in each pass can be measured, for example, using thermometers 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 the rolling stand within the temperature range of this embodiment. The rolling temperature in the intermediate rolling stand can also be calculated based on the actual temperatures of thermometers appropriately installed before and after the thermometers. In contrast, in current hot rolling, temperature control based on such calculations is generally performed.

[0240] (Cooling process)

[0241] In the cooling process, the hot-rolled steel sheet after the hot rolling process is cooled. This cooling can obtain high-strain and moderately fine grains. As a cooling condition, cooling is started 0.10 seconds after the final pass of the finishing rolling (after more than 0.10 seconds), so that the surface temperature of the hot-rolled steel sheet becomes 300°C or higher and Ar3 temperature -20°C or lower after 3 seconds. Here, it is set not to quench the hot-rolled steel sheet immediately. That is, cooling is started more than 0.10 seconds after the final pass of the finishing rolling, so that it becomes 300°C or higher and Ar3 temperature -20°C or lower after 3 seconds. Here, the so-called final pass of the finishing rolling refers to the moment when the front end of the steel sheet passes the rolling discharge side. The so-called start of cooling refers to the moment when the front end of the steel sheet enters the cooling zone of the cooling device and starts accelerated cooling that exceeds natural air cooling. In addition, there is no particular limit on the upper limit of the time elapsed from the start of cooling. For example, as long as cooling starts within 30 seconds from the final pass of the finishing rolling, it is sufficient, and preferably cooling starts within 3.0 seconds. The so-called natural air cooling is cooling at a cooling rate of 1 to 10°C / s.

[0242] By avoiding immediate quenching in this way, a special quenching device is not required, which is advantageous in terms of manufacturing (cost). In addition, if quenching is performed immediately, excessive thermal strain is introduced into the texture of the hot-rolled steel sheet, which in turn causes the {411} <148> Orientation, {100} <011> Orientation aggregation will also weaken the {411} <011> Prioritized aggregation of orientations.

[0243] Furthermore, as cooling conditions, conditions are preferably such that the average crystal grain size of the hot-rolled steel sheet after the cooling step, that is, before cold rolling, becomes 3 to 10 μm.

[0244] In order to adjust the average grain size of the hot-rolled steel sheet before cold rolling to 3 to 10 μm, the temperature may be Ar3 temperature - 20° C. or lower within 3 seconds after the final pass of finish rolling.

[0245] If the temperature of the steel sheet 3 seconds after the final pass of finish rolling is less than 300°C, the average grain size of the hot-rolled steel sheet will become excessively fine. Therefore, the temperature of the steel sheet 3 seconds after the final pass of finish rolling is set to 300°C or higher. This temperature can also be set to 600°C or higher.

[0246] Furthermore, if the temperature at which the steel sheet is cooled after the final pass of finish rolling is stopped is also lower than 300°C, the average grain size of the hot-rolled steel sheet becomes excessively fine. Therefore, the temperature at which the steel sheet is cooled after the final pass of finish rolling is stopped is set to 300°C or higher. This temperature may also be set to 600°C or higher.

[0247] In addition, the average crystal grain size in the hot-rolled steel sheet before cold rolling is measured in the same manner as the average crystal grain size of the non-oriented electrical steel sheet of the present embodiment.

[0248] As described above, by performing phase transformation while imparting appropriate working strain to the γ phase structure, and then imparting appropriate working strain to the α phase structure, and performing appropriate cooling to avoid introducing thermal strain while suppressing the recovery of the working strain, it is possible to form an appropriate crystal structure that does not become excessively refined. If this crystal structure is then cold rolled, the α fibers develop after intermediate annealing, and after the subsequent skin pass rolling and final annealing, the {411} <011> If the crystal structure at this moment is not appropriate, it is difficult for α fibers to develop after cold rolling and intermediate annealing, and sometimes the desired {411} <011> Rate.

[0249] The hot-rolled steel sheet temperature (particularly the finish rolling temperature) and the surface temperature of the hot-rolled steel sheet 3 seconds after the final pass of the finish rolling were measured by the following method.

[0250] In a hot rolling mill line used to manufacture electromagnetic steel sheets, cooling equipment and conveyor lines (e.g., conveyor rollers) are located downstream of the hot rolling mill. A thermometer for measuring the surface temperature of the hot-rolled steel sheet is located on the discharge side of the rolling stand where the final pass of the hot rolling mill is performed. Furthermore, multiple thermometers are arranged along the conveyor line on the conveyor rollers downstream of the rolling stand. Therefore, the hot rolling temperature and the surface temperature of the hot-rolled steel sheet three seconds after the final pass of finish rolling are measured using thermometers located in the hot rolling mill line.

[0251] A cooling device is located downstream of the rolling stand where the final pass is performed. Multiple cooling devices are typically provided, each with a temperature gauge located on the inlet side of the cooling device. The cooling device can be, for example, a conventional water cooling device or a conventional forced air cooling device. Preferably, the cooling device is a water cooling device. The coolant in the water cooling device can be water or a mixture of water and air.

[0252] Thereafter, the hot-rolled steel sheet is not annealed (hot-rolled sheet annealing), but is cold-rolled.

[0253] (Cold rolling process)

[0254] 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, the hot-rolled steel sheet is coiled without hot-rolled steel sheet annealing and then cold-rolled to obtain a rolled steel sheet. Hot-rolled steel sheet annealing as used herein refers to a heat treatment at a temperature of, for example, 900°C or lower and 300°C or higher.

[0255] Cold rolling can be performed using, for example, a tandem mill comprising a plurality of rolling stands arranged in a row (each having a pair of work rolls) to perform multiple passes of rolling. Alternatively, reverse rolling using a Sendzimir mill with a pair of work rolls, for example, can be performed in one or more passes. From the perspective of productivity, multiple passes of rolling using a tandem mill are preferred.

[0256] During cold rolling, cold rolling is performed without annealing during the cold rolling process. For example, when reverse rolling is performed and cold rolling is performed in multiple passes, multiple cold rolling passes are performed without annealing between passes. If annealing is performed between passes, the desired orientation cannot be developed in the subsequent steps.

[0257] Cold rolling can also be performed using a reverse rolling mill and cold rolling can be performed in only one pass. In addition, when cold rolling is performed using a tandem rolling mill, cold rolling is continuously performed in multiple passes (passes in each rolling stand).

[0258] In this embodiment, the cold rolling reduction ratio RR1 (%) is preferably set to 75 to 95%. Here, the cold rolling reduction ratio RR1 is defined as follows.

[0259] Reduction ratio RR1 (%)=(1-sheet thickness after rolling in the final pass of cold rolling / sheet thickness before rolling in the first pass of cold rolling)×100.

[0260] (Intermediate annealing step) In the intermediate annealing step, the rolled steel sheet is subjected to intermediate annealing. In this embodiment, the annealing temperature (intermediate annealing temperature T1) (°C) is preferably controlled to be below 900°C. If the intermediate annealing temperature exceeds the Ac1 temperature, part of the structure of the steel sheet will transform into austenite. Due to the change in crystal orientation accompanying the phase transformation, the steel sheet will be subjected to the following skin-pass rolling and final annealing. <011> Oriented grains cannot grow sufficiently, and sometimes the magnetic flux density does not increase, and the stress sensitivity does not decrease.

[0261] On the other hand, if the intermediate annealing temperature is too low, no recrystallization occurs and the steel will not be re-crystallized during the subsequent skin pass rolling and final annealing. <011> Oriented grains may not grow sufficiently, and the magnetic flux density may not increase, and the stress sensitivity may not decrease. Therefore, the intermediate annealing temperature T1 (°C) is preferably 600°C or higher, and more preferably 700°C or higher.

[0262] The intermediate annealing temperature T1 (° C.) is the sheet temperature (surface temperature) near the extraction port of the annealing furnace.

[0263] The holding time at the intermediate annealing temperature T1 (°C) during the intermediate annealing step can be a time known to those skilled in the art. The holding time at the intermediate annealing temperature T1 (°C) is, for example, 5 to 60 seconds, but is not limited to this. Furthermore, the heating rate to the intermediate annealing temperature T1 (°C) can also be a known condition. The heating rate to the intermediate annealing temperature T1 (°C) is, for example, 10.0 to 20.0°C / second, but is not limited to this.

[0264] The atmosphere during the intermediate annealing is not particularly limited, and for example, an atmosphere gas containing 20% H2 and the remainder N2 (dry) is used. The cooling rate of the steel sheet after the intermediate annealing is not particularly limited, and for example, is 5.0 to 60.0°C / second.

[0265] If the intermediate annealing is completed under the above conditions, the obtained cold-rolled steel sheet can be obtained, which has an α fiber ratio (within a margin of 10°) of 15% or more when measured by SEM-EBSD. In order to make the α fiber ratio (within a margin of 10°) of 15% or more in the stage before skin-pass rolling, it is necessary to set the chemical composition to an appropriate level (the phase transformation temperature Ar3 obtained by formula (1) and the content of Mn, Ni, Cu, etc. are within the specified range), and set the above conditions from hot rolling to intermediate annealing. In particular, the temperature and reduction rate in the final stage of finishing rolling and the subsequent cooling conditions are important. About the easy generation of {411} <011> The oriented α fibers are transformed from partially recrystallized austenite to ferrite in the final stage of hot rolling. The ferrite is then appropriately processed, cooled while maintaining the processing strain and avoiding the introduction of thermal strain. The hot-rolled steel sheet, with an average grain size of 3 to 10 μm, is then cold-rolled and then intermediate annealed, thereby developing α fibers. As described above, excessive reduction above the Ar3 temperature results in a structure characterized by transformation of unrecrystallized austenite, rather than a structure characterized by transformation of partially recrystallized austenite.

[0266] The cold-rolled steel sheet thus produced is subjected to skin pass rolling under the conditions described below to obtain a base sheet of the non-oriented electrical steel sheet of the present embodiment, and is further subjected to final annealing to obtain the non-oriented electrical steel sheet of the present embodiment.

[0267] (Skin-pass rolling process)

[0268] In the skin pass rolling process, the cold-rolled steel sheet after the intermediate annealing process is skin pass rolled to obtain a base non-oriented electrical steel sheet. Specifically, the cold-rolled steel sheet after the intermediate annealing process is rolled (cold rolled) at room temperature in air. For example, a reverse rolling mill or a tandem rolling mill, such as the Sendzimir mill described above, is used for skin pass rolling. The skin pass rolling process yields a non-oriented electrical steel sheet (after skin pass rolling and before final annealing).

[0269] Skin-pass rolling is performed without annealing during the rolling process. For example, when reverse rolling is performed and skin-pass rolling is performed in multiple passes, multiple passes are performed without annealing between passes. Alternatively, skin-pass rolling can be performed in a single pass using a reverse rolling mill. Furthermore, when skin-pass rolling is performed using a tandem rolling mill, rolling is performed continuously in multiple passes (passes in each rolling stand).

[0270] As described above, in this embodiment, after strain is introduced into the steel sheet by hot rolling and cold rolling, the strain introduced into the steel sheet is temporarily reduced by intermediate annealing. Then, skin pass rolling is performed. In this way, the strain excessively introduced by cold rolling is reduced during the intermediate annealing, and the intermediate annealing is performed to suppress the preferential recrystallization of {111} grains in the steel sheet surface, so that {411} <011> Then, during skin pass rolling, an appropriate amount of strain is introduced into each grain in the steel sheet, and in the final annealing in the next step, the grain growth due to expansion is easily caused.

[0271] In the present embodiment, the reduction ratio RR2 in skin pass rolling is set to 5 to 20%. Here, the reduction ratio RR2 is defined as follows.

[0272] Reduction ratio RR2 (%)=(1-sheet thickness after rolling at the final pass in skin pass rolling / sheet thickness before rolling at the first pass in skin pass rolling)×100.

[0273] Here, if the reduction ratio RR2 is less than 5%, the strain is too small, and the final annealing time required for grain growth due to expansion becomes longer. On the other hand, if the reduction ratio RR2 exceeds 20%, the strain is too large, causing normal grain growth instead of expansion, and {411} <148> or {111} <112> Therefore, the reduction ratio RR2 is set to 5 to 20%.

[0274] The number of passes in skin-pass rolling may be only one pass (ie, only one rolling pass) or may be a plurality of rolling passes.

[0275] The number average Gs of the GOS values and the α fiber ratio are obtained by performing recrystallization by intermediate annealing on a steel sheet having an appropriate chemical composition and subjected to appropriate hot rolling and cold rolling, and then performing skin pass rolling under the above conditions.

[0276] The skin pass rolling performed in this embodiment has a significant difference in effect from skin pass rolling performed after final annealing. A predetermined structure can be obtained by sequentially performing hot rolling, cooling, cold rolling, intermediate annealing, skin pass rolling, and final annealing under predetermined conditions.

[0277] (Final annealing process)

[0278] In the final annealing process, the raw sheet of the non-oriented electrical steel sheet after the skin-pass rolling process is subjected to final annealing. Through this final annealing, the strain difference of each crystal orientation caused by the skin-pass rolling is used as a driving force to generate expansion, and the target {411} <011> Oriented grains grow preferentially, and the distribution of the target crystal orientation can be achieved. The annealing conditions can be appropriately set by those skilled in the art while confirming the occurrence of expansion, and there are no special restrictions. In order to properly and fully grow the grains by expansion, batch annealing is preferred. As an example, a temperature of 750°C or more and 900°C or less and a time of more than 2 hours can be cited. Annealing at 800°C for 2 hours is preferred. When the final annealing temperature T2 (°C) is set to less than 750°C, grain growth caused by expansion is difficult to occur sufficiently. In this case, {411} <011> The degree of orientation concentration decreases. In addition, when the final annealing temperature T2 (℃) exceeds 900℃, part of the structure of the steel sheet transforms into austenite, and grain growth due to expansion does not occur, and the desired {411} <011> In addition, when the annealing time is less than 2 hours, the grain growth caused by expansion may not occur sufficiently due to the temperature. <011> The degree of orientation concentration is reduced. The annealing time of the final annealing is not particularly limited, but the effect is saturated even if the annealing time exceeds 10 hours, so the preferred upper limit is 10 hours.

[0279] The heating rate TR2 to the final annealing temperature T2 in the final annealing step may be a heating rate known to those skilled in the art, and may be 40°C / hour or higher and less than 200°C / hour, but is not limited to this range.

[0280] The heating rate TR2 is determined by the following method. A thermocouple is attached to a steel plate having the above chemical composition and having been subjected to the above-described hot rolling and skin pass rolling process to prepare a sample steel plate. The sample steel plate with the thermocouple attached is heated, and the time from the start of the heating process to the final annealing temperature T2 is measured. The heating rate TR2 is determined based on the measured time.

[0281] The atmosphere during the final annealing step is not particularly limited. For example, the atmosphere during the final annealing step can be an atmosphere gas containing 20% by volume of H2 and the remainder of N2 (dry), or a 100% hydrogen atmosphere. The cooling rate of the steel sheet after the final annealing is not particularly limited. For example, the cooling rate can be 0.05 to 20°C / second, but is not limited to this range.

[0282] This final annealing can be performed by the steel sheet manufacturer after skin-pass rolling, for example. However, as a subsequent step to the skin-pass rolling process, the steel sheets can be shipped to a core fabricator without final annealing. The core fabricator then blanks and / or laminates the skin-pass rolled non-oriented electrical steel sheets, then performs final annealing at an annealing temperature of 750°C to 900°C for a minimum of two hours. This method is highly efficient because it can also serve as the "stress relief annealing" typically performed on motor cores by core fabricators or motor manufacturers. Of course, stress relief annealing can also be performed after the final annealed steel sheets are blanked and / or laminated to form core components or core shapes.

[0283] According to the above-described manufacturing method, the non-oriented electromagnetic steel sheet of the present embodiment can be manufactured (including the case where the non-oriented electromagnetic steel sheet is used as a part of the core when punching, lamination, and stress relief annealing are performed).

[0284] In the manufacturing method of this embodiment, for example, shot peening and / or pickling may be performed after the cooling step and before the cold rolling step in the above-mentioned manufacturing process. In shot peening, the hot-rolled steel plate is shot peened to destroy and remove the oxide scale formed on the surface of the hot-rolled steel plate. In pickling, the hot-rolled steel plate is pickled. For example, an aqueous solution of hydrochloric acid is used as a pickling bath. Pickling removes the oxide scale formed on the surface of the steel plate. Shot peening may be performed after the cooling step and before the cold rolling step, and then pickling may be performed. In addition, pickling may be performed after the cooling step and before the cold rolling step without shot peening. Shot peening may be performed after the cooling step and before the cold rolling step without pickling. In addition, shot peening and pickling are optional steps. Therefore, both the shot peening step and the pickling step may not be performed.

[0285] (Insulation Film Formation Step)

[0286] The method for manufacturing an electromagnetic steel sheet according to this embodiment may further include forming an insulating coating on the surface of the steel sheet (non-oriented electromagnetic steel sheet) after the final annealing step by coating. The insulating coating forming step is optional. Therefore, coating may not be performed after the final annealing step.

[0287] There is no particular limitation on the type of insulating coating. The insulating coating may be an organic component or an inorganic component, and the insulating coating may also contain organic and inorganic components. Examples of inorganic components include dichromic acid-boric acid, phosphoric acid, and silica. Examples of organic components include general acrylic acid, acrylic styrene, acrylic silicon, silicon, polyester, epoxy, and fluorine resins. Considering the coating properties, the preferred resin is an emulsion-type resin. Insulating coatings that exert adhesive properties by heating and / or pressurizing may also be applied. Examples of insulating coatings with adhesive properties include acrylic acid, phenolic, epoxy, and melamine resins.

[0288] The non-oriented electrical steel sheet, raw non-oriented electrical steel sheet, and cold-rolled steel sheet of this embodiment are not limited to the above-mentioned production method as long as they have a predetermined chemical composition and crystal orientation and other predetermined items are within the predetermined range.

[0289] The iron core of the present embodiment can be obtained by processing the non-oriented electromagnetic steel sheet of the present embodiment or a raw sheet of the non-oriented electromagnetic steel sheet into an iron core by a known method.

[0290] For example, it can be manufactured by punching and / or laminating the non-oriented electrical steel sheets of the present embodiment.

[0291] Furthermore, an iron core can be manufactured by punching and / or laminating the raw non-oriented electrical steel sheets of this embodiment and performing a final annealing at an annealing temperature of 750°C to 900°C for 2 hours or more. As described above, the final annealing in this case can be performed as a stress relief annealing generally performed on an iron core.

[0292] In any of the above methods, the non-oriented electromagnetic steel sheets or raw non-oriented electromagnetic steel sheets forming the core can be integrated into the core by known methods such as riveting, welding, adhesives, or insulating coatings that exhibit adhesive properties. Examples of blanking and laminating methods include: blanking and laminating the stator together with the rotor as an integral core; rotating and laminating the stators blanked together with the rotor as an integral core; and blanking and laminating the stators, with the direction of the steel sheets having excellent magnetic properties aligned with the direction of the teeth and / or yoke, etc.

[0293] Example

[0294] 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.

[0295] Molten steel was cast to produce ingots having the chemical composition shown in Table 1 below. "Co, etc." in Table 1 indicates the contents of Co, Pt, Pb, and Au. The resulting ingots were then heated and hot-rolled under the conditions shown in Table 2. In this example, the ingot heating temperature (i.e., the heating temperature of the steel material before rolling), which serves as the starting temperature for rough rolling, was used as the starting temperature for rolling.

[0296] Then, after passing the final pass, cooling was performed under the cooling conditions shown in Table 2 (the time from passing the final pass of finish rolling to the start of cooling, and the temperature of the steel sheet 3 seconds after passing the final pass).

[0297] Here, to examine the texture after cooling, a portion of the steel plate was cut away, and the average grain size was measured using the cutting method according to JIS G0551 (2020) on a plane parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the surface. The measurement results are shown in Table 2.

[0298] Next, the hot-rolled steel sheets were pickled for descaling without hot-rolled sheet annealing, and then cold-rolled at a reduction ratio RR1 shown in Table 2. Then, in an atmosphere composed of 20% hydrogen and 80% nitrogen by volume, intermediate annealing was performed by controlling the heating rate to 15.0°C / second and the intermediate annealing temperature T1 to the temperature shown in Table 2 and holding the temperature for 30 seconds.

[0299] Here, in order to investigate the texture of the cold-rolled steel sheet before skin-pass rolling (texture after intermediate annealing), a portion of the steel sheet was removed and the removed specimen was reduced to 1 / 2 the thickness. Then, in the SEM-EBSD measurement area of the processed surface, {hkl} was extracted using OIM Analysis 7.3. <011> Orientation (within a tolerance of 10°), the extracted area is divided by the area of the measurement area to obtain the α fiber ratio A aα The results are shown in Table 3.

[0300] Next, skin pass rolling was performed at the reduction ratio RR2 shown in Table 2.

[0301] Before final annealing, in order to investigate the texture of the original non-oriented electrical steel sheet after skin-pass rolling (texture after skin-pass rolling), a portion of the steel sheet was cut and the cut test piece was reduced to 1 / 2 the thickness. Then, the α fiber ratio As of the processed surface was determined in the same manner as above. α In addition, regarding {100} <011> The ODF intensity of orientation was determined by using OMI Analysis 7.3 in the SEM-EBSD measurement area of the processed surface. ODF was prepared according to the above conditions and the data of the prepared ODF was output. <011> The ODF value of the orientation was used as the ODF intensity. Furthermore, regarding Gs, SEM-EBSD data was analyzed using OMI Analysis 7.3, and the number average of the GOS values was calculated as Gs. The results are shown in Table 3.

[0302] Next, the skin-pass rolled steel sheets were final annealed in a 100% hydrogen atmosphere at a heating rate of 100°C / hour at a final annealing temperature T2 shown in Table 2. The holding time at the final annealing temperature T2 was set to 2 hours.

[0303] In order to investigate the texture of the non-oriented electrical steel sheet after final annealing (texture after final annealing), a portion of the steel sheet was cut off and the cut test piece was reduced in thickness to 1 / 2. <011> The ratios of A411-011 / A411-148 and A411-011 / A100-011 were determined by observing the SEM-EBSD measurement area of the processed surface under the above measurement conditions. <uvw>The maximum intensity in the orientation and in {hkl} <011> The maximum intensity of the orientation is Φ(°) (the maximum intensity of In the SEM-EBSD measurement area of the processed surface, OMI Analysis 7.3 was used to create an ODF according to the above conditions. The data of the created ODF was output and the point where the ODF value was the maximum within the specific orientation range was taken as the point of maximum intensity. Φ of maximum intensity.

[0304] Furthermore, a portion of the steel plate was cut away, and the average grain size was measured by the cutting method of JIS G0551 (2020) on a surface parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the surface.

[0305] The results are shown in Table 3.

[0306] In addition, in order to investigate the magnetic properties after final annealing, the magnetic flux density B50 and iron loss W10 / 400 were measured, and the iron loss degradation rate of the iron loss W10 / 50 under compressive stress was calculated as an indicator of stress sensitivity. Regarding the magnetic flux density B50, as a measurement sample, a 55 mm square single-plate magnetic property test sample was collected in two directions of 0° and 45° to the rolling direction. Then, the two samples were measured, and the value in the direction of 45° relative to the rolling direction was taken as the magnetic flux density B50 (45°) in the 45° direction, and the average value of 0°, 45°, 90°, and 135° relative to the rolling direction was taken as the whole-week average of the magnetic flux density B50 (whole-week). Regarding the iron loss W10 / 400 (45°), the sample collected in the direction of 45° to the rolling direction in the above-mentioned measurement sample was used. Furthermore, regarding the iron loss degradation rate W of the iron loss W10 / 50 under compressive stress in the 45° direction, x [%], when the iron loss W10 / 50 (45° direction) under no stress is recorded as W10 / 50(0) and the iron loss W10 / 50 (45° direction) under 10 MPa compressive stress is recorded as W10 / 50(10), the iron loss degradation rate W is calculated by the following formula x The measurement results are shown in Table 3.

[0307] W x ={W10 / 50(10)-W10 / 50(0)} / W10 / 50(0)

[0308] If the magnetic flux density B50 (entire circumference) is 16.15 T or more, it is determined that the magnetic properties over the entire circumference are excellent.

[0309] If the magnetic flux density B50 (B50(45°)) in the direction 45° relative to the rolling direction is greater than 1.70T, the iron loss W10 / 400 (W100 / 400(45°)) in the direction 45° relative to the rolling direction is less than 13.8W / kg, and the iron loss degradation rate of W10 / 50 under compressive stress in the direction 45° relative to the rolling direction is less than 40%, it is judged that the magnetic properties in the 45° direction are excellent.

[0310] With regard to hot brittleness, the number of cracks having a depth of 1 mm or more penetrating the plate thickness at both end surfaces in the plate width direction (length in the plate width direction) was evaluated within the following ranges: a rolling direction length of 10 m from a position 10 m from the longitudinal front end of the outermost periphery of the hot-rolled plate coil in the rolling direction; a rolling direction length of 10 m from the longitudinal front end of the outermost periphery of the hot-rolled plate coil centered at positions approximately 1 / 4, 1 / 2, and 3 / 4 of the total coil length; and a rolling direction length of 10 m from a position 10 m from the longitudinal front end of the innermost periphery of the coil in the rolling direction. Specifically, since the total length of the hot-rolled sheet coil was 800 m, visual evaluation was conducted at positions 10-20 m, 195-205 m, 395-405 m, 595-605 m, and 780-790 m in the rolling direction from the longitudinal end of the outermost periphery of the coil (10-20 m from the longitudinal end of the innermost periphery of the coil). A "yes" score was given if the number of cracks on both end surfaces was less than 10, and a "no" score was given if the number of cracks on either or both end surfaces was 10 or more.

[0311] In this embodiment, hot-rolled coils were used as the evaluation targets for hot brittleness. However, when evaluating steel plates cut from hot-rolled coils, the end surfaces on both sides of the steel plate in the rolling direction can also be observed at five or more different positions in the rolling direction of the steel plate, in the same manner as described above. For example, observations can be made within a range of approximately 1 / 10 of the total length of the steel plate in the rolling direction, centered at positions approximately 1 / 10, 1 / 4, 1 / 2, 3 / 4, and 9 / 10 of the length of the steel plate in the rolling direction. The total length of the steel plate in the rolling direction can be at least 1 meter.

[0312] Regarding the cost, “Yes” was recorded when the total amount of Mn, Ni, and Cu was less than 2.5%, and “No” was recorded when the total amount of Mn, Ni, and Cu exceeded 2.5%.

[0313] [Table 1-1]

[0314]

[0315] [Table 1-2]

[0316]

[0317] [Table 2-1]

[0318]

[0319] [Table 2-2]

[0320]

[0321] [Table 3-1-1]

[0322]

[0323] [Table 3-1-2]

[0324]

[0325] [Table 3-2-1]

[0326]

[0327] [Table 3-2-1]

[0328]

[0329] The underlined elements in Tables 1 to 3 represent conditions that deviate from the scope of the present disclosure.

[0330] The magnetic flux density B50 (full cycle), magnetic flux density B50 (45°), and iron loss W10 / 400 (45°) of the disclosed example are all good values, and stress sensitivity is low. Furthermore, it can be seen that the disclosed example has no problems with hot brittleness and alloy cost.

[0331] In addition, the disclosure of Japanese Patent Application No. 2023-001934 is incorporated herein by reference in its entirety.

[0332] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application, and technical standard were specifically and individually described.< / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw>

Claims

1. A non-oriented electromagnetic steel sheet, The present invention has the following chemical composition: in terms of mass%, it contains C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and at least one selected from the group consisting of Mg, Ca, S At least one selected from the group consisting of r, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total, where the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content, and P content are expressed in mass % as [C], [Mo], [Cr], [Mn], [Ni], [Cu], [Si], [sol.Al], and [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. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+ [Mo]+[Cu])-46×([Cr]+[Ni])…(1), When {hkl} is measured by SEM-EBSD on a surface parallel to the rolled surface at a depth of 1 / 2 the thickness of the steel plate from the surface, <uvw>When the area ratio of oriented grains to the total field of view is recorded as Ahkl-uvw, A411-011 is 15.0% or more. In the ODF, Φ=20° has the maximum strength at The maximum strength is achieved at Φ=5~35° in the range of Φ=0~90°.< / uvw> The average crystal grain size is 50 μm to 150 μm.

2. The non-oriented electrical steel sheet according to claim 1, The area ratio of the grains of a specific orientation relative to the total field of view when measuring a surface parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the surface of the steel plate by the SEM-EBSD satisfies both the following equations (2) and (3): A411-011 / A411-148≧1.1…(2), A411-011 / A100-011≧2.0…(3).

3. The non-oriented electrical steel sheet according to claim 1, One or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu: less than 2.50% in total.

4. A base plate of a non-oriented electromagnetic steel plate, The present invention has the following chemical composition: in terms of mass%, it contains C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and at least one selected from the group consisting of Mg, Ca, S At least one selected from the group consisting of r, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total, where the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content, and P content are expressed in mass % as [C], [Mo], [Cr], [Mn], [Ni], [Cu], [Si], [sol.Al], and [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. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+ [Mo]+[Cu])-46×([Cr]+[Ni])…(1), The area ratio A of the grains with α-fiber crystal orientation relative to the total field of view when measured by SEM-EBSD on a surface parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the steel plate surface sα More than 20.0%, {100} when measuring and preparing ODF using the above-mentioned SEM-EBSD <011> The ODF strength of the orientation is 15.0 or less, When the number average of GOS with respect to the total field of view when measured by the SEM-EBSD is expressed as Gs, the Gs is 0.8 or more and 3.0 or less.

5. An iron core, It comprises the non-oriented electrical steel sheet according to any one of claims 1 to 3.

6. An iron core, It comprises the base sheet of the non-oriented electrical steel sheet according to claim 4.

7. A cold-rolled steel sheet for use in manufacturing the non-oriented electrical steel sheet according to any one of claims 1 to 3 or the base sheet of the non-oriented electrical steel sheet according to claim 4. The invention has the following chemical composition: containing, in mass%, C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and At least one selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total, where, in percentage by mass, the C content is represented by [C], the Mo content is represented by [Mo], the Cr content is represented by [Cr], the Mn content is represented by [Mn], the Ni content is represented by [Ni], the Cu content is represented by [Cu], the Si content is represented by [Si], the sol.Al content is represented by [sol.Al], and the P content is represented by [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. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+ [Mo]+[Cu])-46×([Cr]+[Ni])…(1), The area ratio A of the grains with α-fiber crystal orientation relative to the total field of view when measured by SEM-EBSD on a surface parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the steel plate surface aα It is more than 15.0%.

8. A method for manufacturing a non-oriented electromagnetic steel sheet, comprising the following manufacturing steps: A hot rolling process for hot-rolling a steel material to obtain a hot-rolled steel plate, wherein the steel material has the following chemical composition: in mass %, C: 0.0100% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: a total of 0% to 0.010%, whereby the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content and P content are expressed as [P] in mass%, 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. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+ [Mo]+[Cu])-46×([Cr]+[Ni])…(1); a cooling step of cooling the hot-rolled steel sheet after the hot rolling step; a cold rolling step of cold-rolling the hot-rolled steel sheet after the cooling step to obtain a cold-rolled steel sheet; An intermediate annealing step of performing intermediate annealing on the cold-rolled steel sheet; a skin-pass rolling step of skin-pass rolling the cold-rolled steel sheet after the intermediate annealing step to obtain a base sheet of a non-oriented electrical steel sheet; and a final annealing step of performing final annealing on the base sheet of the non-oriented electrical steel sheet after the skin temper rolling step; In the hot rolling process, rolling is performed in the following manner: the starting temperature of rolling is higher than the Ar3 temperature + 20°C, the finishing temperature of rolling is lower than the Ar3 temperature, the reduction ratio during the period from the completion of rolling to the time when the rolling first passes through the Ar3 temperature is 15% or more, and the reduction ratio during the period from the time when the rolling first passes through the Ar3 temperature to the time when the rolling first passes through the Ar3 temperature + 20°C is 10% or more, In the cooling step, cooling is started after 0.10 seconds or more from the final pass of the finishing rolling, and the Ar3 temperature is set to 300°C or higher and -20°C or lower after 3 seconds. The reduction rate in the skin-pass rolling process is set to 5 to 20%. In the final annealing step, the annealing temperature is set to 750° C. or higher and 900° C. or lower, and the annealing time is set to 2 hours or longer.

9. A method for producing a base plate of a non-oriented electromagnetic steel sheet, comprising the following steps: A hot rolling process for hot-rolling a steel material to obtain a hot-rolled steel plate, wherein the steel material has the following chemical composition: in mass %, C: 0.0100% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: a total of 0% to 0.010%, whereby the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content and P content are expressed as [P] in mass%, 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. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+ [Mo]+[Cu])-46×([Cr]+[Ni])…(1); a cooling step of cooling the hot-rolled steel sheet after the hot rolling step; a cold rolling step of cold-rolling the hot-rolled steel sheet after the cooling step to obtain a cold-rolled steel sheet; an intermediate annealing step of performing intermediate annealing on the cold-rolled steel sheet; and a skin-pass rolling step of skin-pass rolling the cold-rolled steel sheet after the intermediate annealing step to obtain a base sheet of a non-oriented electromagnetic steel sheet; In the hot rolling process, rolling is performed in the following manner: the starting temperature of rolling is higher than the Ar3 temperature + 20°C, the finishing temperature of rolling is lower than the Ar3 temperature, the reduction ratio during the period from the completion of rolling to the time when the rolling first passes through the Ar3 temperature is 15% or more, and the reduction ratio during the period from the time when the rolling first passes through the Ar3 temperature to the time when the rolling first passes through the Ar3 temperature + 20°C is 10% or more, In the cooling step, cooling is started after 0.10 seconds or more from the final pass of the finishing rolling, and the Ar3 temperature is set to 300°C or higher and -20°C or lower after 3 seconds. The reduction ratio in the skin pass rolling step is set to 5 to 20%.

10. A method for producing the non-oriented electrical steel sheet according to claim 8 or the base sheet of the non-oriented electrical steel sheet according to claim 9, In the cooling step, the average grain size of the hot-rolled steel sheet after the cooling step is set to 3 to 10 μm.

11. A method for producing the non-oriented electrical steel sheet according to claim 8 or the base sheet of the non-oriented electrical steel sheet according to claim 9, The reduction ratio in the cold rolling step is set to 75 to 95%.

12. A method for producing the non-oriented electrical steel sheet according to claim 8 or the base sheet of the non-oriented electrical steel sheet according to claim 9, In the intermediate annealing step, the annealing temperature is set to 900° C. or lower.

13. A method for manufacturing a cold-rolled steel sheet, comprising the following manufacturing steps: A hot rolling process for hot-rolling a steel material to obtain a hot-rolled steel plate, wherein the steel material has the following chemical composition: in mass %, C: 0.0100% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, at least one selected from the group consisting of Mn, Ni and Cu: less than 2.5% in total, Mo: 0% to less than 2.5%, Cr: 0% to less than 2.5%, Ti: 0% to 0.005%, Nb: 0% to 0.005%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: a total of 0% to 0.010%, whereby the C content, Mo content, Cr content, Mn content, Ni content, Cu content, Si content, sol.Al content and P content are expressed as [P] in mass%, 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. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+ [Mo]+[Cu])-46×([Cr]+[Ni])…(1); a cooling step of cooling the hot-rolled steel sheet after the hot rolling step; a cold rolling step of cold-rolling the hot-rolled steel sheet after the cooling step to obtain a cold-rolled steel sheet; and An intermediate annealing step is performed on the cold-rolled steel sheet. In the hot rolling step, rolling is performed in such a manner that the starting temperature of rolling exceeds the Ar3 temperature + 20°C, the finishing temperature of rolling is lower than the Ar3 temperature, the reduction ratio during the period from the completion of rolling to the time when the rolling first passes through the Ar3 temperature is 15% or more, and the reduction ratio during the period from the time when the rolling first passes through the Ar3 temperature to the time when the rolling first passes through the Ar3 temperature + 20°C is 10% or more, In the cooling step, cooling is started after 0.10 seconds or more have passed since the final pass of finish rolling, and the temperature is set to 300° C. or higher and Ar3 temperature -20° C. or lower after 3 seconds.

14. The method for manufacturing a cold-rolled steel sheet according to claim 13, In the cooling step, the average grain size of the hot-rolled steel sheet after the cooling step is set to 3 to 10 μm.

15. The method for producing a cold-rolled steel sheet according to claim 13 or 14, The reduction ratio in the cold rolling step is set to 75 to 95%.

16. The method for producing a cold-rolled steel sheet according to claim 13 or 14, In the intermediate annealing step, the annealing temperature is set to 900° C. or lower.

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