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

Abstract

This non-oriented electromagnetic steel plate has a prescribed chemical composition. The chemical composition satisfies 1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni]): 750 to 1050. When Ahkl-uvw represents the surface area ratio of crystal grains in a \{hkl\}<uvw> orientation to the entire field of view when a plane parallel to a rolled surface at a depth at 1 / 2 of the plate thickness from the top surface is measured by SEM-EBSD, A411-011 is greater than or equal to 15.0%. According to an ODF for φ2=45°, the non-oriented electromagnetic steel plate has the maximum intensity at φ1=0 to 10° for φ1=0 to 90° and Φ=20°, has the maximum intensity at φ=5 to 35° for φ1=0° and Φ=0 to 90°, and has an average crystalline particle diameter of 50 to 150 μm.

Description

[Technical field]

[0001] The present disclosure relates to a non-oriented electrical steel sheet, a base sheet for a non-oriented electrical steel sheet, a core, a cold-rolled steel sheet, a method for manufacturing a non-oriented electrical steel sheet, a method for manufacturing a base sheet for a non-oriented electrical steel sheet, and a method for manufacturing a cold-rolled steel sheet. [Background technology]

[0002] Electrical steel sheets are used as materials for the cores (iron cores) of electrical equipment. Examples of electrical equipment include drive motors installed in automobiles, motors for various compressors such as those used in air conditioners and refrigerators, and even generators for home or industrial use. These electrical equipment require high energy efficiency, compactness, and high output. For this reason, electrical steel sheets used as the cores of electrical equipment are required to have low iron loss and high magnetic flux density. Texture control is one solution for achieving low iron loss and high magnetic flux density, and technologies have been proposed to develop a texture (α-fiber) that has an easy axis of magnetization within the steel sheet plane, is advantageous for improving magnetic properties, and allows for relatively easy accumulation through rolling processing in hot rolling and cold rolling, which are essential steps in steel sheet manufacturing. Specifically, <110> A texture is formed whose direction is approximately parallel to the rolling direction (RD).

[0003] In Patent Documents 1 to 3, the {100} <011> A method for developing the orientation is disclosed, and it is stated that the transformation temperature is lowered and the structure is refined by rapid cooling after hot rolling.

[0004] Specifically, Patent Document 1 describes that the steel sheet is cooled to 250°C or less at a cooling rate of 200°C / sec or more within 3 seconds after hot rolling, that no annealing is performed between hot rolling and cold rolling, and that the cumulative reduction in cold rolling is 88% or more. <011> It is said that it is possible to manufacture electromagnetic steel sheets that are concentrated in a directional direction.

[0005] In addition, Patent Document 2 discloses a method for producing an electrical steel sheet containing 0.6 mass % to 3.0 mass % of Al, and the method is similar to the method described in Patent Document 1, in which {100} <011> It is described that it is possible to manufacture magnetic steel sheets with concentrated orientation.

[0006] On the other hand, Patent Document 3 describes that the finish rolling temperature in hot rolling is set to the Ac3 transformation point or higher, and the steel sheet temperature is cooled to 250°C within 3 seconds after hot rolling, or that the finish rolling temperature is set to the Ac3 transformation point -50°C or lower, and the steel sheet is cooled at a cooling rate faster than natural cooling. In addition, the manufacturing method described in Patent Document 3 involves performing two cold rolling steps with intermediate annealing in between, no annealing is performed between the hot rolling and the first cold rolling step, and the cumulative reduction rate in the second cold rolling step is set to 5 to 15%. As a result, the {100} <011> It is said that it is possible to manufacture electromagnetic steel sheets that are concentrated in a directional direction.

[0007] In all of the methods described in Patent Documents 1 to 3, the {100} <011> When manufacturing magnetic steel sheets with orientation integration, if the finish rolling temperature in hot rolling is set to Ac3 temperature or higher, rapid cooling immediately after hot rolling is required. Rapid cooling increases the cooling load after hot rolling. Considering operational stability, it is preferable to suppress the load on the rolling mill that performs cold rolling.

[0008] On the other hand, to improve the magnetic properties, the {411} orientation was rotated 20 degrees from the {100} orientation. Technologies for developing the {411} orientation have also been proposed. Patent Documents 4 to 7 all disclose technologies for developing the {411} orientation, and describe optimizing the grain size in a hot-rolled sheet and strengthening the α-fiber in the texture of the hot-rolled sheet.

[0009] Specifically, Patent Document 4 describes a method of cold rolling a hot-rolled sheet in which the concentration of the {211} orientation is higher than that of the {411} orientation, and a cumulative reduction ratio in the cold rolling is set to 80% or more. This makes it possible to manufacture an electrical steel sheet in which the {411} orientation is concentrated on the sheet surface.

[0010] Patent Documents 5 and 6 also describe that the slab heating temperature is 700°C to 1150°C, the start temperature of finish rolling is 650°C to 850°C, the end temperature of finish rolling is 550°C to 800°C, and the cumulative reduction in cold rolling is 85 to 95%. This makes it possible to produce an electrical steel sheet with grains accumulated in the {100} and {411} orientations on the steel sheet surface.

[0011] On the other hand, Patent Document 7 describes a method for producing non-oriented electrical steel sheets in which α-fibers are developed to the vicinity of the surface layer of a hot-rolled coil steel sheet by strip casting or the like, and the {h11}<1 / h12> orientation, especially {100} <012> ~{411} <148> It is described that the orientation is recrystallized.

[0012] Furthermore, as shown in Patent Documents 8 to 12, various investigations have been conducted on component systems in which a γ→α phase transformation occurs in order to promote the development of the {100} crystal orientation that enhances magnetic properties. Furthermore, technical document 13 discloses a steel sheet having excellent stress sensitivity and magnetic properties in the 45° direction. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Publication No. 2017-145462 [Patent Document 2] Japanese Patent Application Publication No. 2017-193731 [Patent Document 3] Japanese Patent Publication No. 2019-178380 [Patent Document 4] Japanese Patent No. 4218077 [Patent Document 5] Japanese Patent No. 5256916 [Patent Document 6] Japanese Patent Application Publication No. 2011-111658 [Patent Document 7] Japanese Patent Publication No. 2019-183185 [Patent Document 8] Patent No. 4029430 [Patent Document 9] Patent No. 6319465 [Patent Document 10] WO2021 / 095846 [Patent Document 11] Patent Publication No. 2021-080501 [Patent Document 12] JP 2020-100860 A [Patent Document 13] WO2021 / 205880 Summary of the Invention [Problem to be solved by the invention]

[0014] As a result of examining the above-mentioned techniques, the present inventors have found that <011> It was found that if one tried to improve the magnetic properties by strengthening the orientation, rapid cooling immediately after hot rolling would be necessary, which would impose a heavy manufacturing load. <011> We realized that when a steel plate with reinforced orientation is used as a material for a crimped core, the core properties expected from the material may not be obtained. <011> It was thought that the orientation was responsible for the change in magnetic properties in response to stress, specifically the deterioration of magnetic properties (stress sensitivity) when compressive stress was applied, particularly the deterioration of iron loss.

[0015] In addition, in the techniques disclosed in Patent Documents 4 to 7, although the {411} orientation is developed, the in-plane orientation is <011> It was found that the magnetic properties at 45° from the rolling direction of the steel sheet, which is a characteristic of α-fiber, were not sufficiently high. <011> The lack of alignment, i.e., the large deviation from the α-fiber, is a factor that inhibits accumulation in the {411} plane orientation, and it is possible that this is the reason why the magnetic properties are not sufficiently improved. In the technologies of Patent Documents 8 to 12, which have been studied for a composition system in which a γ→α phase transformation occurs in order to promote the development of the {100} crystal orientation that improves magnetic properties, one of the key points is to refine the hot-rolled structure. By using a steel composition with a low γ→α phase transformation temperature, accumulating a large amount of strain in the γ phase by low-temperature γ region hot rolling, and then transforming from there, a fine-grained α phase structure is achieved at the time of hot-rolling. To achieve this, the addition of γ-stabilizing elements such as Mn, Cu, and Ni is utilized from the viewpoint of lowering the transformation temperature and delaying recovery recrystallization to promote the accumulation of strain. However, Mn is known as a segregation element, and if the amount added is increased, it segregates in the center of the hot-rolled sheet and causes cracks in the hot-rolled sheet. Cu also significantly reduces hot brittleness. Ni has little effect on hot workability, and is actually effective in improving hot brittleness caused by Cu, but its high alloy cost has prevented it from being actively used. In addition, the {100} crystal orientation developed by the technology utilizing the γ→α phase transformation is less likely to be random within the plane, and the {100} <011> Since the orientation is the main factor, it cannot be said that the in-plane anisotropy is sufficiently reduced, and a new type of crystal orientation control is required. Furthermore, the technology of Patent Document 13, which discloses a steel sheet having excellent stress sensitivity and magnetic properties in the 45° direction, requires the addition of γ-stabilizing elements such as Mn, Cu, and Ni, which poses problems of hot brittleness and alloy cost.

[0016] In view of the above problems, the present disclosure has an object to provide a non-oriented electrical steel sheet that has low stress sensitivity, in particular a low rate of iron loss degradation due to stress, and can obtain excellent magnetic properties in the 45° direction, while having a chemical composition in which the content of gamma stabilizing elements such as Mn, Cu, and Ni is suppressed so that hot brittleness and alloy costs do not become problems, a core using the same, a base sheet for a non-oriented electrical steel sheet for producing the non-oriented electrical steel sheet, a cold-rolled steel sheet, a method for producing a non-oriented electrical steel sheet, a method for producing a base sheet for a non-oriented electrical steel sheet, and a method for producing a cold-rolled steel sheet. [Means for solving the problem]

[0017] The present inventors have conducted extensive research to solve the above problems. As a result, the chemical composition, the {411} <011> It was found that it is important to control the ratio of crystal grains with the orientation and the average crystal grain size. It was also found that, when controlling these, it is preferable to optimize the grain size after hot rolling and the reduction ratio in cold rolling. Specifically, based on the premise of an α-γ transformation system chemical composition that ensures hot workability and reduces alloy costs by minimizing the amount of austenite stabilizing elements such as Mn added, γ→α transformation occurs during hot rolling, and rolling is performed under specified conditions before and after the transformation to optimize the grain size. Furthermore, cold rolling is performed with a specified reduction ratio, the temperature of intermediate annealing is controlled within a specified range, and skin pass rolling (second cold rolling) is performed with an appropriate reduction ratio, followed by annealing, whereby the {411} <011> It has become clear that it is preferable to easily develop crystal grains in the direction of the crystal orientation. Based on this finding, the present inventors have further conducted intensive research and have arrived at the following aspects of the disclosure.

[0018] [1] A non-oriented electrical steel sheet according to an embodiment of the present disclosure comprises, by 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%, S b: 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: 0% to 0.010% in total, and has a transformation temperature Ar3 (°C) defined by the following formula (1) of 750 to 1050°C, with the balance being Fe and impurities, where the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is [P], in mass%, {hkl} when measured by SEM-EBSD on a surface parallel to the rolling surface at a depth of 1 / 2 the sheet thickness from the steel sheet surface <uvw>When the area ratio of the crystal grains of the orientation to the entire field of view is expressed as Ahkl-uvw, A411-011 is 15.0% or more, and in the ODF of φ2 = 45°, it has a maximum intensity at φ1 = 0 to 10° among φ1 = 0 to 90°, Φ = 20°, and has a maximum intensity at Φ = 5 to 35° among φ1 = 0°, Φ = 0 to 90°, The average crystal grain size is 50 μm to 150 μm. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni]) ···(1) [2] In the non-oriented electrical steel sheet described in [1] above, the area ratio of crystal grains of a specific orientation to the entire field of view when a plane parallel to the rolling surface at a depth of 1 / 2 the sheet thickness from the surface of the steel sheet is measured by the SEM-EBSD may satisfy both of the following formulas (2) and (3): A411-011 / A411-148 ≧1.1 (2) A411-011 / A100-011 ≧2.0 (3) [3] In the non-oriented electrical steel sheet according to the above [1] or [2], one or more elements selected from Mn, Ni, Co, Pt, Pb, Au, and Cu may be contained in a total amount of less than 2.50%. [4] In the base sheet of the non-oriented electrical steel sheet according to another embodiment of the present disclosure, the following components are contained in the base sheet: 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 Mg a transformation temperature Ar3 (°C) defined by the following formula (1) is 750 to 1050°C, with the balance being Fe and impurities, where the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is [P], and the transformation temperature Ar3 (°C) defined by the following formula (1) is 750 to 1050°C, with the balance being Fe and impurities, The area ratio A of crystal grains with α-fiber crystal orientation to the entire field of view measured by SEM-EBSD on a surface parallel to the rolled surface at a depth of 1 / 2 the sheet thickness from the steel sheet surface sα is 20.0% or more, The {100} <011> The azimuth ODF strength is 15.0 or less, When the number average value of GOS in the entire field of view measured by the SEM-EBSD is defined as Gs, the Gs is 0.8 or more and 3.0 or less. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni]) ···(1) [5] A core according to another embodiment of the present disclosure includes the non-oriented electrical steel sheet according to any one of [1] to [3]. [6] A core according to another embodiment of the present disclosure includes an original sheet for the non-oriented electrical steel sheet according to [4]. [7] A cold-rolled steel sheet according to another embodiment of the present disclosure is a cold-rolled steel sheet used for manufacturing the non-oriented electrical steel sheet according to any one of [1] to [3] or the original sheet for the non-oriented electrical steel sheet according to [4], 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, 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 Mg, Ca, Sr, Ba, Ce, L one or more selected from the group consisting of a, Nd, Pr, Zn and Cd: 0% to 0.010% in total, and has a transformation temperature Ar3 (°C) defined by the following formula (1) of 750 to 1050°C, with the balance being Fe and impurities, where the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al] and the P content is [P], with the C content being ... Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al] and the P content is [P], with the balance being Fe and impurities, The area ratio A of crystal grains with α-fiber crystal orientation to the entire field of view measured by SEM-EBSD on a surface parallel to the rolled surface at a depth of 1 / 2 the sheet thickness from the steel sheet surface aα is 15.0% or more. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni]) ···(1) [8] A method for producing a non-oriented electrical steel sheet according to another embodiment of the present disclosure includes, by 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 Mg, Ca, Sr, Ba, Ce, La, a hot rolling process for hot rolling a steel material having a chemical composition containing 0% to 0.010% in total of one or more selected from the group consisting of Nd, Pr, Zn, and Cd, and having a transformation temperature Ar3 (°C) of 750 to 1050°C as defined by the following formula (1) when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is [P], with the balance being Fe and impurities; A cooling process for cooling the hot-rolled steel sheet after the hot rolling process; A cold rolling process of cold rolling the hot rolled steel sheet after the cooling process to obtain a cold rolled steel sheet; An intermediate annealing process for performing intermediate annealing on the cold-rolled steel sheet; a skin pass rolling process in which the cold rolled steel sheet after the intermediate annealing process is subjected to skin pass rolling to obtain a base sheet of a non-oriented electrical steel sheet; a finish annealing process for performing finish annealing on the original sheet of the non-oriented electrical steel sheet after the skin pass rolling process; having In the hot rolling step, rolling is performed such that the rolling start temperature is higher than Ar3 temperature + 20°C, the rolling completion temperature is lower than Ar3 temperature, the rolling reduction rate during the period from the completion of rolling to the first passing through Ar3 temperature is 15% or more, and the rolling reduction rate during the period from the first passing through Ar3 temperature to the first passing through Ar3 temperature + 20°C is 10% or more, In the cooling step, cooling is started 0.10 seconds or more after the final pass of the finish rolling, and the temperature is reduced to 300°C or higher and Ar3 temperature -20°C or lower after 3 seconds, The reduction ratio in the skin pass rolling process is 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. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni]) ···(1) [9] In a method for producing an original sheet of a non-oriented electrical steel sheet according to another embodiment of the present disclosure, the following components are contained in the raw sheet: 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 Mg, Ca, Sr, Ba, Ce, L a hot rolling process of hot rolling a steel material having a chemical composition containing 0% to 0.010% in total of at least one selected from the group consisting of A, Nd, Pr, Zn and Cd, and having a transformation temperature Ar3 (°C) of 750 to 1050°C as defined by the following formula (1) when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al] and the P content is [P], with the balance being Fe and impurities; A cooling process for cooling the hot-rolled steel sheet after the hot rolling process; A cold rolling process of cold rolling the hot rolled steel sheet after the cooling process to obtain a cold rolled steel sheet; An intermediate annealing process for performing intermediate annealing on the cold-rolled steel sheet; a skin pass rolling process in which the cold rolled steel sheet after the intermediate annealing process is subjected to skin pass rolling to obtain a base sheet of a non-oriented electrical steel sheet; having In the hot rolling step, rolling is performed such that the rolling start temperature is higher than Ar3 temperature + 20°C, the rolling completion temperature is lower than Ar3 temperature, the rolling reduction rate during the period from the completion of rolling to the first passing through Ar3 temperature is 15% or more, and the rolling reduction rate during the period from the first passing through Ar3 temperature to the first passing through Ar3 temperature + 20°C is 10% or more, In the cooling step, cooling is started 0.10 seconds or more after the final pass of the finish rolling, and the temperature is reduced to 300°C or higher and Ar3 temperature -20°C or lower after 3 seconds, The reduction rate in the skin pass rolling step is set to 5 to 20%. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni]) ···(1)

[10] In the method for producing the non-oriented electrical steel sheet according to the above [8] or the base sheet for the non-oriented electrical steel sheet according to the above [9], 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.

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

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

[13] In a method for producing a cold rolled steel sheet according to another embodiment of the present disclosure, the following elements are contained in the steel sheet: 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 0.005%, 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: 0% to 0.010% in total, and the C content, in mass%, is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is a hot rolling process for hot rolling a steel material having a chemical composition in which a transformation temperature Ar3 (°C) defined by the following formula (1) is 750 to 1050°C, with the balance being Fe and impurities, where [P] is a hot rolling process for obtaining a hot rolled steel sheet; A cooling process for cooling the hot-rolled steel sheet after the hot rolling process; A cold rolling process of cold rolling the hot rolled steel sheet after the cooling process to obtain a cold rolled steel sheet; An intermediate annealing process for performing intermediate annealing on the cold-rolled steel sheet; having In the hot rolling step, rolling is performed such that the rolling start temperature is higher than Ar3 temperature + 20°C, the rolling completion temperature is lower than Ar3 temperature, the rolling reduction rate during the period from the completion of rolling to the first passing through Ar3 temperature is 15% or more, and the rolling reduction rate during the period from the first passing through Ar3 temperature to the first passing through Ar3 temperature + 20°C is 10% or more, In the cooling step, cooling is started 0.10 seconds or more after the final pass of finish rolling, and the temperature is reduced to 300° C. or more and Ar3 temperature −20° C. or less after 3 seconds. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni]) ···(1)

[14] In the method for producing a cold-rolled steel sheet according to the above item

[12] , 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.

[15] In the method for producing a cold rolled steel sheet according to the above

[12] or

[13] , the cold rolling step may have a rolling reduction of 75 to 95%.

[16] The method for producing a cold-rolled steel sheet according to the above

[12] or

[13] , In the intermediate annealing step, the annealing temperature may be 900° C. or lower. Effect of the Invention

[0019] According to the above aspects of the present disclosure, it is possible to provide a non-oriented electrical steel sheet that has low stress sensitivity, in particular a low rate of iron loss degradation due to stress, and excellent magnetic properties in the 45° direction, a core using the same, a base plate for a non-oriented electrical steel sheet for producing the non-oriented electrical steel sheet, a cold-rolled steel sheet, a method for producing a non-oriented electrical steel sheet, a method for producing a base plate for a non-oriented electrical steel sheet, and a method for producing a cold-rolled steel sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a non-oriented electrical steel sheet according to one embodiment of the present disclosure (the non-oriented electrical steel sheet according to the present embodiment), a base sheet for the non-oriented electrical steel sheet (the base sheet for the non-oriented electrical steel sheet according to the present embodiment), a cold-rolled steel sheet (the cold-rolled steel sheet according to the present embodiment), and manufacturing methods thereof will be described in detail.

[0021] First, the chemical composition of the non-oriented electrical steel sheet according to this embodiment and the steel material (raw material) used in the manufacture thereof will be described. In the following description, "%", which is the unit of content of each element contained in the non-oriented electrical steel sheet or steel material, means "mass %" unless otherwise specified. Furthermore, a numerical range expressed using "to" means a range including the numerical values ​​written before and after "to" as the lower and upper limits. Furthermore, it is self-evident that each element of the following embodiment can be combined with each other. Moreover, the chemical composition of the non-oriented electrical steel sheet indicates the content when the base material excluding the coating, etc. is taken as 100%. In addition, in the numerical ranges described in stages in this specification, the upper limit value of a certain numerical range may be replaced by the upper limit value of another numerical range described in stages, or may be replaced by a value shown in the examples. In the numerical ranges described in stages in this specification, the lower limit value of a certain numerical range may be replaced by the lower limit value of another numerical range described in stages, or may be replaced by a value shown in the examples. In addition, in this specification, "non-oriented electrical steel sheet" and "original sheet of non-oriented electrical steel sheet" include not only coil-shaped or cut-plate steel sheet, but also steel sheet and original sheet processed into a specific shape as a material for products (components) such as motor cores, and further steel sheet and original sheet that are laminated after processing to form motor cores.

[0022] The non-oriented electrical steel sheet, the base sheet of the non-oriented electrical steel sheet, and the cold-rolled steel sheet according to the present embodiment have a chemical composition in which ferrite-austenite transformation (hereinafter, α-γ transformation) can occur to a certain extent (a chemical composition in which a certain amount of γ is generated when heated even if the entirety is not transformed to γ), and include 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: 0.0100% or less, and % 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 0.400%, and 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, and further, the contents of C, Si, P, sol.Al, Mn, Mo, Cu, Cr, and Ni satisfy the specified conditions described below, and the balance is Fe and impurities. Examples of impurities include those contained in raw materials such as ores and scraps, and those contained in the manufacturing process.

[0023] In addition, in the non-oriented electrical steel sheet, the base sheet of the non-oriented electrical steel sheet, and the cold-rolled steel sheet according to this embodiment, one or more elements selected from Mn, Ni, Co, Pt, Pb, Au, and Cu are preferably contained in a total amount of less than 2.50%.

[0024] (C: 0.0100% or less) C is an element that increases iron loss and causes magnetic aging by precipitating fine carbides and inhibiting grain growth. Therefore, the lower the C content, the better. This phenomenon is significant when the C content exceeds 0.0100%. For this reason, the C content is set to 0.0100% or less. The C content is preferably 0.0050% or less, and more preferably 0.0025% or less. There is no particular lower limit for the C content, but in consideration of the cost of decarburization during refining, the C content is preferably 0.0005% or more.

[0025] (Si: 1.50% to 4.00%) Silicon is an element that increases electrical resistance, decreases eddy current loss, reduces iron loss, and increases the yield ratio to improve punching workability into iron cores. If the silicon content is less than 1.50%, these effects cannot be fully obtained. Therefore, the silicon content is set to 1.50% or more. On the other hand, if the Si content exceeds 4.00%, the magnetic flux density decreases, punching workability decreases due to an excessive increase in hardness, and cold rolling becomes difficult, etc. Therefore, the Si content is set to 4.00% or less.

[0026] (sol.Al:0.0001%~1.00%) Sol.Al is an element that increases electrical resistance, reduces eddy current loss, and reduces iron loss. Sol.Al is also an element that contributes to improving the relative magnitude of magnetic flux density B50 with respect to saturation magnetic flux density. Here, magnetic flux density B50 is the magnetic flux density in a magnetic field of 5000 A / m. If the sol.Al content is less than 0.0001%, these effects cannot be fully obtained. Furthermore, Al also has the effect of promoting desulfurization in steelmaking. Therefore, the sol.Al content is set to 0.0001% or more. On the other hand, if the sol.Al content exceeds 1.00%, the magnetic flux density decreases, so the sol.Al content is set to 1.00% or less. Incidentally, sol. Al means acid-soluble Al that is not in the form of an oxide such as Al2O3 and is soluble in acid.

[0027] (S:0.0100% or less) S is not an essential element, and is contained, for example, as an impurity in steel. S precipitates as fine MnS and inhibits recrystallization and grain growth during annealing. Therefore, the lower the S content, the better. Such an increase in iron loss and a decrease in magnetic flux density due to the inhibition of recrystallization and grain growth are significant when the S content exceeds 0.0100%. For this reason, the S content is set to 0.0100% or less. There is no particular lower limit for the S content, but in consideration of the cost of desulfurization treatment during refining, the S content is preferably set to 0.0003% or more.

[0028] (N:0.0100% or less) N deteriorates magnetic properties through the formation of fine precipitates such as TiN and AlN. Therefore, the lower the N content, the better. Such deterioration of magnetic properties is significant when the N content exceeds 0.0100%, so the N content is set to 0.0100% or less. There is no particular lower limit for the N content, but considering the cost of denitrification treatment during refining, the N content is preferably set to 0.0010% or more.

[0029] (One or more selected from the group consisting of Mn, Ni, and Cu: less than 2.5% in total) These elements are effective in inducing the α-γ transformation, but on the other hand, they reduce hot workability and increase alloy costs, so the total content of these elements must be kept below 2.5%. Also, if the total content is 2.5% or more, the magnetic flux density may decrease. On the other hand, since these elements are effective in reducing iron loss, it is preferable to contain them in total at 1.5% or more. In particular, Ni is known to have an effect of improving the deterioration of hot brittleness caused by Cu, and it is preferable in terms of hot brittleness to contain about half or less of the Cu content, with the total content of one or more selected from Mn, Ni, and Cu being within a range of less than 2.5%. In addition, Mn lowers the Ar3 transformation point, and in the component system of the non-oriented electrical steel sheet according to this embodiment, it is possible to refine the crystal grains of the hot-rolled sheet by 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 viewpoint, it is more preferable to contain 0.50% or more of Mn. More preferably, it is 1.00% or more. On the other hand, Mn is an element that easily segregates, and if the content increases, it not only causes cold work cracks due to segregation, but also reduces the saturation magnetic flux density and prevents an increase in the magnetic flux density of the steel sheet. In addition, MnS is excessively generated, and the cold workability is reduced. 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 mass% or less, and more preferably 2.0 mass% or less. The upper limit of the Cu content is not particularly limited, but is preferably 1.5 mass% or less, and more preferably 1.0 mass% or less. The lower limit of the Cu content is not particularly limited, but may be, for example, 0.01% or more. The upper limit of the Ni content is preferably 1.0 mass% or less, and more preferably 0.7 mass% or less. The lower limit of the Ni content is not particularly limited, and may be 0%, but may be, for example, 0.01% or more. 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, but may be, for example, 0.10% or more, 0.50% or more, 1.00% or more, or even 2.00% or more.

[0030] (One or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu: less than 2.50% in total) In addition to the above-mentioned Mn, Ni, and Cu, Co, Pt, Pb, and Au reduce the hot workability and increase the alloy cost, so in this embodiment, the content of these elements is preferably kept to less than 2.50% in total. Furthermore, since these elements reduce the magnetic flux density, it is preferable to keep the total content of these elements to less than 2.00%. The lower limit of the total content of Mn, Ni, Co, Pt, Pb, Au, and Cu is not particularly limited, but may be, for example, 0.10% or more, 0.50% or more, 1.00% or more, or even 2.00% or more. In particular, since the alloy cost of Co, Pt, Pb, and Au is high, active addition should be avoided. Furthermore, even considering the control of the Ar3 transformation point, which is one of the features of this embodiment, it is preferable to control the Ar3 transformation point by containing Mn, Ni, and Cu. For this reason, the total amount of Co, Pt, Pb, and Au should be less than 0.5%, more preferably 0.1% or less, and should be kept within the range of unavoidable elements, and there is no need to actively add them (they may be 0%).

[0031] Furthermore, in order for the α-γ transformation to occur and for good magnetic properties to be obtained, the following condition must be satisfied: In other words, when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol.Al content is [sol.Al], and the P content is [P], the transformation temperature Ar3 (°C) defined by the following formula (1) satisfies 750 to 1050°C. Ar3(℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.Al]-120×([Mn]+[Mo]+[Cu])-46×([Cr]+[Ni]) ···(1) If the formula (1) above is not satisfied, even if the α-γ transformation occurs, the transformation point is not in the appropriate temperature range, so sufficient magnetic flux density cannot be obtained even if the manufacturing method described below is applied. If Ar3 is less than 750°C, the hot rolling temperature becomes low, so the deformation resistance increases and the load on the rolling mill becomes too large, and the amount of added elements increases, which leads to a decrease in the toughness of the hot-rolled sheet and cold-rolled sheet, so 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, which increases the load on the heating furnace, or the composition system does not cause γ→α transformation, so this value is set as the upper limit.

[0032] (Mo: 0.0% to less than 2.5%) Mo is an element that lowers the Ar3 transformation point and enables the refinement of the grain size of the hot-rolled sheet by phase transformation in the chemical composition of the non-oriented electrical steel sheet according to this embodiment. Therefore, Mo may be added as necessary, and it is preferable to add 0.1% or more. On the other hand, since the addition of 2.5% or more of Mo significantly reduces the cold workability, the Mo content is set to less than 2.5%.

[0033] (Cr: 0.0% to less than 2.5%) Cr is an element that lowers the Ar3 transformation point and enables the grain size of the hot-rolled sheet to be refined by phase transformation in the chemical composition of the non-oriented electrical steel sheet according to this embodiment, and also has the effect of improving not only strength adjustment and corrosion resistance, but also high-frequency characteristics in particular. Therefore, Cr may be contained as necessary, and it is preferable to contain 0.1% or more. On the other hand, excessive Cr content not only saturates the effect and increases the raw material cost, but also reduces the saturation magnetic flux density and prevents an increase in the magnetic flux density of the steel sheet. For this reason, the Cr content is set to less than 2.5%.

[0034] (Ti: 0% to 0.005%) Ti, when present as a solid solution or TiN, inhibits recrystallization and contributes to refinement of the austenite grain size. Therefore, Ti may be contained. When Ti is contained, it is preferable that the Ti content is 0.001% or more. On the other hand, if the Ti content exceeds 0.005%, various precipitates such as TiN, TiS, and TiC are generated, which deteriorates the iron loss characteristics, so the Ti content is set to 0.005% or less.

[0035] (Nb: 0% to 0.005%) Nb, when present in the form of a solid solution or NbN, inhibits recrystallization and contributes to refinement of the austenite grain size. Therefore, Nb may be contained. When Nb is contained, it is preferable that the Nb content is 0.001% or more. On the other hand, if the Nb content exceeds 0.005%, various precipitates such as NbN and NbC are generated, which deteriorates the iron loss characteristics, so the content is set to 0.005% or less.

[0036] (Sn: 0%~0.40%, Sb: 0%~0.40%) Sn and Sb improve the texture after cold rolling and recrystallization, and increase the magnetic flux density. Therefore, these elements may be contained as necessary. In order to impart further effects such as magnetic properties, it is preferable to contain one or more elements selected from the group consisting of 0.02% to 0.40% Sn and 0.02% to 0.40% Sb. On the other hand, excessive content of these elements embrittles the steel, so the Sn content and Sb content are both set to 0.40% or less.

[0037] (P:0%~0.400%) P is an element effective for ensuring the hardness of the steel sheet after recrystallization. In addition, P is also an element that has a favorable effect on the magnetic properties. Therefore, P may be contained. To obtain these effects, the P content is preferably 0.020% or more. On the other hand, excessive P embrittles steel, so the P content is set to 0.400% or less.

[0038] (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) Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd react with S in molten steel during casting of the molten steel to form precipitates of sulfides or oxysulfides, or both. Hereinafter, Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd may be collectively referred to as "elements that form coarse precipitates". The particle size of the precipitates of the elements that form coarse precipitates is about 1 μm to 2 μm, which is much larger than the particle size (about 100 nm) of fine precipitates such as MnS, TiN, AlN, TiC and NbC. Therefore, these fine precipitates adhere to the precipitates of the elements that form coarse precipitates, and are less likely to inhibit recrystallization and grain growth during annealing such as intermediate annealing. In order to fully obtain these effects, the total content of these elements is preferably 0.0005% or more. More preferably, it is 0.001% or more. On the other hand, if the total content of these elements exceeds 0.010%, the total amount of sulfides or oxysulfides or both will be excessive, which will inhibit recrystallization and grain growth during annealing such as intermediate annealing. Therefore, the total content of the elements that form coarse precipitates is set to 0.010% or less.

[0039] In this embodiment, the balance of the chemical composition other than the above may be Fe and impurities. The impurities refer to elements that are mixed in the steel raw materials and / or during the steelmaking process. do.

[0040] The chemical composition is determined by the following method. The chemical composition can be measured by a general analysis method for steel. For example, the chemical composition can be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Specifically, the chemical composition can be determined by measuring test pieces taken from the steel plate with a specified measuring device under conditions based on a previously prepared calibration curve. C and S can be measured using the combustion-infrared absorption method, and N can be measured using the inert gas fusion-thermal conductivity method. O can be measured using the inert gas fusion-non-dispersive infrared absorption method. If the surface has an insulating coating, it may be mechanically removed using a minitor or the like before being subjected to analysis.

[0041] Next, the texture of the non-oriented electrical steel sheet according to this embodiment will be described. First, a method for measuring the area ratio of specific orientation grains in the non-oriented electrical steel sheet according to the present embodiment will be described. The area ratio of specific orientation grains was measured using OIM Analysis 7.3 (manufactured by TSL) under the following measurement conditions using electron backscatter diffraction (EBSD). The specific orientation of interest is extracted from the area measured using a Scanning Electron Microscope (SEM) equipped with a 10-k Scattering Diffraction (K Scattering Diffraction) (the tolerance is set to 10°, hereafter referred to as within 10° tolerance). The area extracted is divided by the area of ​​the measured area to find the percentage. This percentage is taken as the area ratio of grains with the specific orientation. Hereinafter, the crystal orientation will be described as being within a tolerance of 10°. In other words, the crystal orientation will have a tolerance of within ±5°.

[0042] Details of the measurement conditions for determining the area ratio of each orientation grain are as follows. Measurement equipment: SEM model number "JSM-6400 (manufactured by JEOL)" and EBSD detector model number "HIKARI (manufactured by TSL)" were used. Step spacing: 0.3μm (after intermediate annealing and skin pass rolling), or 5.0μm (after final annealing) Magnification: 1000x (after intermediate annealing and skin pass rolling), or 100x (after final annealing) Measurement target: Surface parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the surface Measurement area: Rectangular area of ​​1000μm or more x 1000μm or more

[0043] In the non-oriented electrical steel sheet according to this embodiment, the steel sheet surface (if an insulating coating is present on the surface, the steel sheet surface excluding the insulating coating, the same applies below) is subjected to electron backscatter diffraction analysis in the manner described above. The {411} <011> rate({hkl} <uvw>The area ratio of crystal grains with orientation (within a tolerance of 10°) to the entire field of view, expressed as Ahkl-uvw, (A411-011) shall be 15.0% or more. {411} <011> If the ratio is less than 15.0%, excellent magnetic properties cannot be obtained. <011> The ratio is set to 15.0% or more, preferably 25.0% or more. There is no particular upper limit, but it is set to, for example, 60% or less.

[0044] Furthermore, in the non-oriented electrical steel sheet according to this embodiment, when the surface is measured by SEM-EBSD, in the ODF at φ2=45°, the maximum strength is at φ1=0 to 10° among φ1=0 to 90° and Φ=20°, and the maximum strength is at Φ=5 to 35° among φ1=0° and Φ=0 to 90°. The maximum strength is found at φ1=0~10° among φ1=0~90° and Φ=20°. <uvw>In the direction of {411} <011> It is synonymous with having a maximum intensity near the azimuth. {411} <011> The direction is {411} <148> etc. {411} <uvw>It has superior magnetic properties in the 45° direction compared to other directions. It is more preferable that it has the maximum strength at φ1=0~5° among φ1=0~90° and Φ=20°. On the other hand, when the surface was measured by SEM-EBSD, the maximum intensity was observed at Φ=5-35° among Φ=0-90° at Φ1=0°, which is {hkl} <011> In the direction of {411} <011> It is synonymous with having a maximum intensity near the azimuth. {411} <011> The orientation has excellent magnetic properties and {100} <011> {hkl} etc. <011> Since it has a lower stress sensitivity than other orientations, there is less magnetic deterioration caused by stress generated by the crimped core, etc. It is more preferable to have the maximum strength at Φ=20 to 30° among Φ=0° and Φ=0 to 90°.

[0045] This section explains how to determine the maximum strength within a specific orientation range in steel plate and the strength of a specific orientation (ODF strength). In the area measured by SEM-EBSD, an orientation distribution function (ODF) is created under the following conditions using OIM Analysis 7.3. The data of the created ODF is then output, and the maximum ODF value within the specific orientation range (range specified by angles of φ1 and Φ) is regarded as the maximum strength. In addition, the ODF value of a specific orientation (orientation specified by angles of φ1 and Φ) is regarded as the ODF strength of that orientation.

[0046] The details of the conditions for creating ODF are as follows: Series Rank(L):16 ·Gaussian Half-Width[degrees]:5 ·Sample Symmetry: Orthotropic(Rolled sheet) ·Bunge Euler Angles: φ1=0~90°, φ2=45°, Φ=0~90°

[0047] Furthermore, in the non-oriented electrical steel sheet according to this embodiment, it is preferable that the area ratio of crystal grains having a specific orientation (within a tolerance of 10°) relative to the entire field of view (whole field of view) when measured by SEM-EBSD satisfies both of the following formulas (2) and (3). A411-011 / A411-148 ≧1.1 (2) A411-011 / A100-011 ≧2.0 (3)

[0048] For equation (2), {411} <011> The direction is {411} <148> etc. {411} <uvw>Compared to other orientations, the magnetic properties in the 45° direction are superior. Therefore, {411} <011> The rate is {411} <148> It is preferable to exceed the rate, {411} <011> The rate is {411} <011> This is more than 1.1 times the rate of A411-148. It is more preferable that the ratio of A411-011 to A411-148 is 1.1 or more. There is no upper limit to the ratio of A411-011 to A411-148, but it is set to, for example, 50 or less. In addition, for equation (3), the stress sensitivity of the magnetic properties is {411} <011> The direction is {100} <011> Because it is low compared to the direction, <011> The rate is {100} <011> It is preferable to exceed the rate, <011> The rate is {100} <011> It is more preferable that the ratio is 2.0 times or more (the ratio of A100-011 to A411-011 is 2.0 or more). There is no upper limit to the ratio of A100-011 to A411-011, but it is set to 50 or less, for example.

[0049] Next, the average crystal grain size of the non-oriented electrical steel sheet according to this embodiment will be described. If the average crystal grain size is too small without the crystal grains being coarsened, the iron loss will deteriorate. On the other hand, if the crystal grains are excessively coarsened and the average crystal grain size is too large, not only will the workability deteriorate, but the eddy current loss will also deteriorate. Therefore, the average crystal grain size of the non-oriented electrical steel sheet is set to 50 μm to 150 μm. The grain size is measured, for example, by the cutting method of JIS G0551 (2020) in a plane parallel to the rolling surface at a depth of 1 / 2 the sheet thickness from the steel sheet surface.

[0050] Next, the thickness of the non-oriented electrical steel sheet according to this embodiment will be described. The thickness of the non-oriented electrical steel sheet according to this embodiment is not particularly limited. The preferred thickness of the non-oriented electrical steel sheet according to this embodiment is 0.10 to 0.50 mm. Usually, as the thickness becomes thinner, the iron loss becomes lower, but the magnetic flux density becomes lower. In view of this, if the thickness is 0.10 mm or more, the iron loss becomes lower and the magnetic flux density becomes higher. A more preferred lower limit of the thickness is 0.12 mm, and a more preferred lower limit is 0.14 mm. Also, if the thickness is 0.50 mm or less, low iron loss can be maintained. A more preferred upper limit of the thickness is 0.35 mm, and a more preferred upper limit is 0.25 mm.

[0051] The above-mentioned non-oriented electrical steel sheet is characterized by a non-oriented electrical steel sheet manufactured by hot rolling, cooling, cold rolling, intermediate annealing, skin pass rolling, and finish annealing, which will be described later.

[0052] Next, the characteristics of the original sheet of the non-oriented electrical steel sheet before finish annealing (after skin pass rolling) will be described.

[0053] The original sheet of the non-oriented electrical steel sheet according to this embodiment before finish annealing after skin pass rolling has the following GOS (Grain Orientation Spread) value. The GOS for the entire field of view when measured by SEM-EBSD (hereinafter also referred to as the "GOS value") is the average of the orientation differences between all measurement points (pixels) within the same grain, and the GOS value is high in crystal grains with a lot of distortion. If the GOS value is small after skin pass rolling, that is, in a low distortion state, grain growth due to bulging is likely to occur in the next process of finish annealing. Therefore, the number average value Gs of the GOS value after skin pass rolling is set to 3.0 or less. On the other hand, if the number-average Gs of the GOS value is less than 0.8, the amount of strain becomes too small, and the final annealing time required for grain growth due to bulging becomes long. Therefore, the number-average value Gs of the GOS value after skin pass rolling is set to 0.8 or more and 3.0 or less.

[0054] The method for calculating Gs will be explained. The SEM-EBSD data obtained when the above crystal orientation was specified was analyzed using OIM Analysis 7.3 to determine the number-average GOS value, which was designated as Gs. When calculating the GOS value, it is necessary to define the grain size, the details of which are as follows. Grain Tolerance Angle: 5° Minimum Grain Size:2 Minimum Conficence Index: 0 The number average value Gs of the GOS value of each crystal grain determined based on this definition is calculated. In OIM Analysis 7.3, the number average value (written as Number on the software) can be calculated at the same time by calculating a GOS histogram using the Chart function.

[0055] In addition, in the original sheet of non-oriented electrical steel sheet after skin pass rolling (before finish annealing), the area ratio A of crystal grains having α-fiber crystal orientation to the entire field of view measured by SEM-EBSD was sα The larger the α-fiber ratio (hereinafter also referred to as "α-fiber ratio"), the more advantageous the magnetic properties after final annealing. Therefore, in the base sheet of the non-oriented electrical steel sheet after skin pass rolling (before final annealing) according to this embodiment, the α-fiber ratio (A sα ) shall be 20.0% or more. sα is preferably 25.0% or more. sα The upper limit of the α-fiber ratio (A) is not particularly limited, but is, for example, 70% or less. sα The lower limit of may be 25.0% or more, and preferably 30.0% or more. In this embodiment, the α fiber is {hkl} <011> This is the direction.

[0056] The method for measuring the α-fiber ratio will be described. In the measurement area by SEM-EBSD at a depth of 1 / 2 the plate thickness from the surface, {hkl} <011> The orientation is extracted (within a tolerance of 10°). The extracted area is divided by the area of ​​the measurement region to determine the percentage. This percentage is the α-fiber ratio. The measurement region (i.e. the entire field of view) using SEM-EBSD is a cross section in the thickness direction at the center of the sheet width, with a size of 1000μm or more x 1000μm or more. The measurement conditions using SEM-EBSD are those described in the measurement conditions for determining the area ratio of oriented grains above.

[0057] In addition, in the case of the original sheet of the non-oriented electrical steel sheet according to this embodiment before finish annealing after skin pass rolling, the {100} <011> The ODF strength of the orientation is set to 15.0 or less, where {100} <011> The orientation ODF intensity is the ODF value at φ1=0° and Φ=0° created using SEM-EBSD data when the above crystal orientation was specified. {411} <011> The orientation has excellent magnetic properties and {100} <011> Since it has a lower stress sensitivity than the other orientations, there is less magnetic deterioration in crimped cores, etc. After skin pass rolling (before finish annealing), the {100} <011> By making the ODF strength of the {411} orientation less than 15.0, the {411} <011> It can strengthen the direction. {100} <011> The lower limit of the azimuth ODF strength is not particularly limited, but may be set to, for example, -0.1.

[0058] {100} <011> The ODF strength of a specific orientation, including the orientation, is determined in the same manner as for the non-oriented electrical steel sheet described above.

[0059] The non-oriented electrical steel sheet according to the present embodiment can be used to form a core, and can be widely applied to applications requiring magnetic properties (high magnetic flux density and low core loss). Examples of applications of the core are as follows. (A) Servo motors, stepping motors, and compressors used in electrical equipment (B) Driving motors used in electric vehicles and hybrid vehicles. Here, vehicles include automobiles, motorcycles, trains, etc. (C) Generator (D) Iron cores, choke coils, and reactors for various applications (E) Current sensors, etc.

[0060] The non-oriented electrical steel sheet according to the present embodiment can be used for applications other than those mentioned above. The non-oriented electrical steel sheet according to the present embodiment is particularly suitable for use as a split core designed to have the main magnetization direction of the core at an angle of 45° from the rolling direction of the steel sheet, and is further suitable for split cores of drive motors for electric vehicles or hybrid vehicles that are used in the high frequency range of 1000 Hz or more.

[0061] It should be noted here that the above industrial advantages can be obtained not only when the non-oriented electrical steel sheet according to this embodiment is punched and laminated to form a core, but also when the original sheet of the non-oriented electrical steel sheet according to this embodiment is punched and laminated to form a core, and then an appropriate heat treatment is performed. Therefore, in the present disclosure, both the core formed by laminating the non-oriented electrical steel sheet according to this embodiment and the core formed by laminating the original sheet of the non-oriented electrical steel sheet according to this embodiment are covered by this disclosure. These are merely differences in the timing of "finish annealing" in the production process, that is, whether the "finish annealing" described below is performed on the steel sheet before the core is formed or on the core after the core is formed, and favorable effects can be obtained in either case. The timing of "finish annealing" will be described in detail later. It is also possible to use the core formed by laminating the original sheets of the non-oriented electrical steel sheet according to this embodiment without finish annealing. In this case, the magnetic properties are not particularly good, but the strain due to skin pass rolling accumulates and the yield strength is high. For this reason, it is considered to be preferably used as a rotor core in which suppression of deformation due to centrifugal force accompanying high speed rotation is more important than magnetic properties.

[0062] Next, the cold-rolled steel sheet according to this embodiment will be described. The cold-rolled steel sheet according to this embodiment is a cold-rolled steel sheet used for producing the above-mentioned non-oriented electrical steel sheet.

[0063] When producing a non-oriented electrical steel sheet from a cold-rolled steel sheet, the chemical composition does not substantially change, so the chemical composition of the cold-rolled steel sheet according to this embodiment is in the same range as that of the non-oriented electrical steel sheet according to the above-mentioned embodiment.

[0064] In addition, the cold-rolled steel sheet according to this embodiment has an area ratio A of crystal grains having an α-fiber crystal orientation to the entire field of view when a surface parallel to the rolling surface at a depth of 1 / 2 the sheet thickness from the steel sheet surface is measured by SEM-EBSD. aα is 15.0% or more. A aα When is less than 15.0%, the α-fiber ratio (A sα ) is not more than 20.0% and {411} after final annealing <011> The rate will not exceed 15.0%. Area ratio A of crystal grains with α-fiber crystal orientation aα There is no particular upper limit, but it may be set to, for example, 70% or less. aα The lower limit of may be 20.0% or more, and preferably 25.0% or more. The method for measuring the crystal orientation is the same as that for the non-oriented electrical steel sheet described above.

[0065] Next, an example of a method for manufacturing the non-oriented electrical steel sheet, the base sheet of the non-oriented electrical steel sheet, and the 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 process, a cooling process, a cold rolling process, an intermediate annealing process, a skin pass rolling process (light reduction cold rolling process), and a finish annealing process. Furthermore, by carrying out the steps before the finish annealing (hot rolling step, cooling step, cold rolling step, intermediate annealing step, and skin pass rolling step), a base sheet for the non-oriented electrical steel sheet according to this embodiment can be obtained. Furthermore, the cold-rolled steel sheet according to the present embodiment can be obtained by the steps before intermediate annealing (hot rolling step, cooling step, cold rolling step, and intermediate annealing step). Preferred conditions for each step will now be described. The Ar3 temperature is the transformation temperature Ar3 (°C) defined by the above formula (1).

[0066] (Hot rolling process) In the hot rolling process, hot rolling is performed on the steel material satisfying the above-mentioned chemical composition to obtain a hot rolled steel sheet. The hot rolling process includes a heating process and a rolling process.

[0067] The steel material is, for example, a slab produced by normal continuous casting, and the steel material having the above-mentioned composition is produced by a known method. For example, molten steel is produced in a converter or electric furnace. The produced molten steel is subjected to secondary refining in a degassing facility or the like to produce molten steel having the above-mentioned chemical composition (the chemical composition does not change substantially in the subsequent steps). The molten steel is cast into a slab by a continuous casting method or an ingot casting method. The cast slab may be subjected to blooming rolling.

[0068] In the heating process, it is preferable to heat the steel material having the above-mentioned chemical composition to 1000 to 1200° C. Specifically, the steel material is charged into a heating furnace or a soaking furnace and heated in the furnace. The holding time at the above heating temperature in the heating furnace or the soaking furnace is not particularly limited, but is, for example, 30 to 200 hours.

[0069] In the rolling process, the steel material heated in the heating process is rolled in multiple passes to produce a hot-rolled steel sheet. Here, "pass" means that the steel sheet passes through one rolling stand having a pair of work rolls and is subjected to rolling reduction. For example, hot rolling may be performed by tandem rolling using a tandem rolling mill including multiple rolling stands arranged in a row (each rolling stand having a pair of work rolls) to perform multiple passes, or by reverse rolling using a pair of work rolls to perform multiple passes. From the viewpoint of productivity, it is preferable to perform multiple rolling passes using a tandem rolling mill.

[0070] In the rolling process (rough rolling and finish rolling), the above-mentioned steel material is heated and hot-rolled. The steel material is, for example, a slab produced by normal continuous casting. The slab is heated to the Ar3 temperature or higher, which is a temperature range in which the steel structure becomes a γ phase. Hot rolling is started in a temperature range in which the steel structure becomes a γ phase (hereinafter, this temperature range may be referred to as the γ range), and is performed in the γ range except for a necessary number of passes including the final pass of the finish rolling, and is completed by performing a necessary number of passes including the final pass in a temperature range in which the α phase exists in the steel structure (hereinafter, this temperature range may be referred to as the α range). Generally, the front to middle stages of rough rolling and finish rolling are performed in the γ range, and the rear stage of finish rolling is performed in the α range. In this embodiment, rolling is performed so that the starting temperature of rolling (i.e., the heating temperature of the steel before rolling) is above Ar3 temperature + 20°C, the completion temperature of rolling (i.e., finish rolling temperature FT) is below Ar3 temperature, the reduction ratio during the period from the completion of rolling to the first passage through Ar3 temperature (i.e., the total reduction ratio in the temperature range from the finish rolling temperature FT to the Ar3 temperature in the final α range) is 15% or more, and the reduction ratio during the period from the first passage through Ar3 temperature to the first passage through Ar3 temperature + 20°C (i.e., the total reduction ratio in the temperature range from Ar3 temperature to Ar3 + 20°C immediately before rolling in the final α range) is 10% or more. In this way, the total reduction in the temperature range from Ar3 temperature to Ar3+20°C immediately before the final rolling in the α region is set to 10% or more. There is no upper limit to this reduction, but it is set to, for example, 40% or less. Furthermore, the rolling reduction in the temperature range from the final rolling temperature FT to the Ar3 temperature in the final α region is set to a total of 15% or more, taking into consideration the case of rolling in multiple passes. There is no upper limit to this total rolling reduction, but it is set to, for example, 40% or less. Here, the upper limit of the rolling start temperature is not particularly limited, but is set to, for example, 1200° C. or lower. Further, the lower limit of the rolling completion temperature (that is, the finish rolling temperature FT) is not particularly limited, but is set to, for example, Ar3 temperature -100°C or more. The starting temperature of rolling (i.e., the heating temperature of the steel material before rolling) is the starting temperature of rough rolling, and refers to the surface temperature of the steel material when the steel material is heated before rough rolling. The rolling completion temperature (i.e., the finish rolling temperature FT) refers to the surface temperature of the hot-rolled steel sheet immediately after finish rolling. In addition, temperatures such as Ar3 temperature indicate the surface temperature of the steel material or steel plate.

[0071] Rolling at temperatures above Ar3+20°C just before the final rolling in the α region has almost no effect on the grain size of the deformed γ grains before the phase transformation, but coarse deformed α grains are formed after the transformation, resulting in the {411} <011> The lower limit of the rolling temperature is the Ar3 temperature. If the rolling reduction ratio in the temperature range between Ar3 and Ar3+20°C immediately before the final rolling in the α region is less than 10%, the accumulation of strain in the deformed γ grains before the phase transformation is insufficient, resulting in the formation of coarse deformed α grains, and the {411} <011> The rolling reduction in the temperature range of Ar3 temperature or higher and Ar3+20°C or lower is preferably 15% or higher, more preferably 20% or higher. Although there is no upper limit for the total rolling reduction, a reduction of more than 40% places too much strain on the rolling mill, so the upper limit is preferably set at 40%. If the rolling reduction rate in the final α region is less than 15% in the temperature range between the FT temperature and the Ar3 temperature, the processed α grains after phase transformation from the processed γ grains cannot accumulate sufficient processing strain in the α region, and the {411} <011> Accumulation in the crystal orientation is less likely to occur. The rolling reduction in the temperature range of the finish rolling temperature FT or more and less than the Ar3 temperature is preferably 20% or more, more preferably 25% or more. Although there is no upper limit to the rolling reduction, a reduction rate of more than 40% places too much strain on the rolling mill, so the upper limit is preferably 40%.

[0072] In this embodiment, the reduction ratio RR0 in the hot rolling is defined as follows. Reduction rate RR0 (%) = (1 - thickness after rolling in the temperature range of the final pass in hot rolling / thickness before rolling in the temperature range of the first pass in hot rolling) x 100

[0073] The lower limit temperature for rolling in the α region is not particularly limited, but since a lower rolling temperature increases the load on the rolling mill, it is preferable to set the lower limit temperature to 600° C. or higher. The rolling temperature may fluctuate above or below the specified judgment temperature (Ar3 temperature or Ar3+20°C) during the rolling pass due to the competition between the temperature drop caused by roll contact and cooling lubricant and the temperature rise caused by processing. In this embodiment, such a situation is handled as follows. In a rolling pass, it is assumed that the temperature at the entry side is TPI (℃), the thickness at the entry side is TCI (mm), the temperature at the exit side is TPO (℃), and the thickness at the exit side is TCO (mm), and furthermore that the thickness change and temperature change during the rolling pass change while maintaining a simple linear relationship. In other words, if the thickness at a specific point in time during a rolling pass is TCa (mm) and the temperature is TPa (℃), it is assumed that the following formula always holds true during the rolling pass. (TCa-TCO) / (TCI-TCO)=(TPa-TPO) / (TPI-TPO) This makes it possible to determine the plate thickness at that point in time even when the specified judgment temperature in this manufacturing method (Ar3 temperature, or Ar3+20°C) is reached during a rolling pass. In other words, the plate thickness TCa (mm) when a specific temperature TPa (℃) is reached during the rolling pass is: TCa=TCO+(TCI-TCO)×(TPa-TPO) / (TPI-TPO) can be obtained by:

[0074] It should be noted that the above assumption also assumes that the exit temperature of the rolling pass will be higher than the entry temperature. In other words, even in a situation where a steel sheet whose entry temperature TPI of the pass is lower than the Ar3 temperature rises in temperature due to processing heat in the pass and is discharged at an exit temperature TPO of Ar3 temperature or higher, it is determined that the steel sheet has been rolled in the γ range (temperature range of Ar3 temperature or higher and Ar3+20°C or lower) required for the present disclosure in the latter half of the pass. It is also possible that the temperature fluctuations on either side of the Ar3 temperature may occur over multiple passes. In such a case, in this embodiment, the rolling conditions in the α region are for the "final rolling process in the α region". In addition, the rolling conditions in the γ region are for the "rolling process in the γ region immediately before the above-mentioned 'final rolling process in the α region'". In other words, when the rolling temperature after starting hot rolling in the γ region changes as follows: γ region (start of hot rolling) ⇒ α region 1 ⇒ γ region 1 ⇒ α region 2 ⇒ γ region 2 ⇒ α region 3 (end of hot rolling), if the α region 3 and the γ region 2 meet the conditions of this embodiment, it is possible to obtain the steel sheet of this embodiment.

[0075] The rolling temperature in each pass can be measured, for example, by a temperature gauge installed at the entry or exit of the rolling stand that performs the reduction of the target pass. Also, it is not necessary to install temperature gauges at the entry and exit of all rolling stands whose temperature range falls within the range of this embodiment, and the rolling temperature in the intermediate rolling stands may be calculated from the actual temperatures of temperature gauges appropriately installed before and after them. Rather, in current hot rolling, control using such calculated temperatures is usually performed.

[0076] (cooling process) In the cooling process, the hot-rolled steel sheet after the hot rolling process is cooled. This cooling provides high distortion and moderately fine crystal grains. As for the cooling conditions, cooling is started 0.10 seconds or more after passing the final pass of finish rolling (after 0.10 seconds or more have elapsed), and the surface temperature of the hot-rolled steel sheet is cooled so that it is 300°C or higher and Ar3 temperature -20°C or lower after 3 seconds. Here, the hot-rolled steel sheet is not immediately quenched. In other words, cooling is started 0.10 seconds or more after the final pass of finish rolling, and it is 300°C or higher and Ar3 temperature -20°C or lower after 3 seconds. Here, passing the final pass of finish rolling means the time when the front end of the steel sheet passes the rolling exit side. The start of cooling means that 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 upper limit on the elapsed time for starting cooling, but for example, cooling may be started within 30 seconds after the final pass of finish rolling, and it is preferable to start cooling within 3.0 seconds. Natural cooling refers to cooling at a rate of 1 to 10° C. / s. By avoiding the immediate quenching in this way, special quenching equipment is not required, which is also advantageous in terms of manufacturing (cost). In addition, when the hot-rolled steel sheet is quenched immediately after rolling, excessive thermal strain is introduced, and the texture after the subsequent finish annealing becomes {411} <148> Direction and <011> Accumulating in the direction of {411} <011> It also weakens preferential accumulation along a certain direction. The cooling conditions are preferably such that the average crystal grain size in the hot-rolled steel sheet after the cooling step, that is, before cold rolling, is 3 to 10 μm.

[0077] In order to make the average crystal grain size in the hot-rolled steel sheet before cold rolling 3 to 10 μm, the temperature may be Ar3 temperature -20° C. or less within 3 seconds after passing the final pass of finish rolling. If the temperature of the steel sheet 3 seconds after passing the final pass of finish rolling is less than 300°C, the average crystal grain size in the hot-rolled steel sheet will be excessively refined. Therefore, the temperature of the steel sheet 3 seconds after passing the final pass of finish rolling is set to 300°C or higher. The temperature may be 600°C or higher. In addition, if the temperature at which the cooling of the steel sheet after passing through the final pass of the finish rolling is stopped is less than 300°C, the average grain size of the hot-rolled steel sheet will be excessively refined. Therefore, the temperature at which the cooling of the steel sheet after passing through the final pass of the finish rolling is stopped is set to 300°C or higher. This temperature may be 600°C or higher. The average grain size in the hot-rolled steel sheet before cold rolling is measured in the same manner as the average grain size in the non-oriented electrical steel sheet according to this embodiment. As described above, by transforming the γ phase structure with an appropriate processing strain, and then applying an appropriate processing strain to the α phase structure, and then performing appropriate cooling while suppressing the recovery of the processing strain and avoiding the introduction of thermal strain, it is possible to obtain a suitable crystal structure that is not excessively refined. If this crystal structure is then cold-rolled, α fibers will develop after intermediate annealing, and {411} fibers, which are not normally developed after the subsequent skin pass and final annealing, will develop. <011> If the crystal structure at this stage is not appropriate, it will be difficult for the α-fiber to develop after cold rolling and intermediate annealing, and the desired {411} <011> The rate may not be available.

[0078] The hot-rolled steel sheet temperature (particularly the finish rolling temperature) and the surface temperature of the hot-rolled steel sheet 3 seconds after passing the final pass of finish rolling are measured by the following method. In a hot rolling equipment line used for manufacturing electrical steel sheets, a cooling device and a conveying line (e.g., conveying rollers) are arranged downstream of the hot rolling mill. A thermometer for measuring the surface temperature of the hot rolled steel sheet is arranged at the exit side of the rolling stand that performs the final pass of the hot rolling mill. In addition, a plurality of thermometers are arranged along the conveying line on the conveying rollers arranged downstream of the rolling stand. Therefore, the hot rolling temperature and the surface temperature of the hot rolled steel sheet 3 seconds after passing the final pass of the finish rolling are measured by the thermometer arranged in the hot rolling equipment line. The cooling device is arranged downstream of the rolling stand that performs the final pass. Generally, a plurality of cooling devices are arranged, and a temperature gauge is arranged at the inlet side of each cooling device. The cooling device may be, for example, a well-known water cooling device or a well-known forced air cooling device. Preferably, the cooling device is a water cooling device. The cooling liquid of the water cooling device may be water or a mixed fluid of water and air.

[0079] Thereafter, the hot-rolled steel sheet is subjected to cold rolling without being annealed (hot-rolled sheet annealing).

[0080] (Cold rolling process) In the cold rolling process, the hot rolled steel sheet after the cooling process is cold rolled to obtain a rolled steel sheet. Specifically, the hot rolled steel sheet is coiled without hot rolled sheet annealing, and the hot rolled sheet is cold rolled to obtain a rolled steel sheet. The hot rolled sheet annealing here means, for example, a heat treatment in which the temperature rise is 900°C or less and 300°C or more. Cold rolling may be performed, for example, by tandem rolling using a tandem rolling mill including a plurality of rolling stands arranged in a row (each rolling stand having a pair of work rolls) to perform multiple passes. Alternatively, reverse rolling may be performed using a Sendzimir rolling mill or the like having a pair of work rolls to perform single pass or multiple passes. From the viewpoint of productivity, it is preferable to perform multiple passes using a tandem rolling mill.

[0081] In cold rolling, the cold rolling is performed without performing annealing treatment during the cold rolling. For example, when performing reverse rolling and performing cold rolling in multiple passes, the cold rolling is performed in multiple passes without performing annealing treatment between passes of cold rolling. If annealing is performed between passes, it is not possible to develop the desired orientation in the process described below. Cold rolling may be performed in only one pass using a reverse rolling mill, or in the case of performing cold rolling using a tandem rolling mill, cold rolling is performed continuously in multiple passes (passes at each rolling stand).

[0082] In this embodiment, the reduction rate RR1 (%) in the cold rolling is preferably set to 75 to 95%. Here, the reduction rate RR1 is defined as follows. Reduction rate RR1 (%) = (1-thickness after the final pass of cold rolling / thickness before the first pass of cold rolling) x 100

[0083] (Intermediate annealing process) In the intermediate annealing step, the rolled steel sheet is subjected to intermediate annealing. In this embodiment, it is preferable to control the annealing temperature (intermediate annealing temperature T1) (°C) to 900°C or less. If the intermediate annealing temperature exceeds the Ac1 temperature, a part of the structure of the steel sheet is transformed into austenite, and due to the change in crystal orientation caused by the transformation, the {411} <011> In some cases, the oriented grains do not grow sufficiently, the magnetic flux density does not increase, and the stress sensitivity does not decrease. On the other hand, if the intermediate annealing temperature is too low, recrystallization will not occur, and the {411} <011> In some cases, the oriented grains do not grow sufficiently, the magnetic flux density does not increase, and the stress sensitivity does not decrease. Therefore, the intermediate annealing temperature T1 (°C) is preferably set to 600°C or higher, and more preferably set to 700°C or higher. The intermediate annealing temperature T1 (°C) is the sheet temperature (surface temperature) in the vicinity of the extraction port of the annealing furnace.

[0084] The holding time at the intermediate annealing temperature T1 (°C) in the intermediate annealing step may 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 thereto. The temperature increase rate up to the intermediate annealing temperature T1 (°C) may also be a known condition. The temperature increase rate up to the intermediate annealing temperature T1 (°C) is, for example, 10.0 to 20.0°C / second, but is not limited thereto.

[0085] The atmosphere during intermediate annealing is not particularly limited, but for example, an atmospheric gas (dry) containing 20% ​​by volume of H2 and the remainder of N2 is used. The cooling rate of the steel sheet after intermediate annealing is not particularly limited, but is, for example, 5.0 to 60.0°C / sec.

[0086] When intermediate annealing is completed under the above conditions, the cold rolled steel sheet obtained has an α-fiber ratio (within a 10° tolerance) of 15.0% or more as measured by SEM-EBSD, and is a cold rolled steel sheet according to this embodiment. In order to achieve an α-fiber ratio (within a 10° tolerance) of 15.0% or more at the stage before skin pass rolling, it is necessary to have an appropriate chemical composition (the transformation temperature Ar3 obtained by formula (1) and the contents of Mn, Ni, Cu, etc. are within a predetermined range) and to maintain the above-mentioned conditions from hot rolling to intermediate annealing. In particular, the temperature and reduction rate at the final stage of finish rolling and the cooling conditions thereafter are important. {411} <011> Alpha fibers, which are easy to form orientation, are developed by transforming partially recrystallized austenite to ferrite in the final stage of hot rolling, further processing the ferrite moderately, and then cooling to avoid the introduction of thermal strain while maintaining the processing strain, and then cold rolling the hot-rolled steel sheet with an average grain size of 3 to 10 μm after hot rolling, followed by intermediate annealing. As mentioned above, if the reduction amount just above the Ar3 temperature is excessive, the structure will be transformed from unrecrystallized austenite, and will no longer be transformed from partially recrystallized austenite. The cold-rolled steel sheet produced in this manner is subjected to skin pass rolling under the conditions described below to produce the base sheet of the non-oriented electrical steel sheet according to this embodiment, and is further subjected to finish annealing to produce the non-oriented electrical steel sheet according to this embodiment.

[0087] (Skin pass rolling process) In the skin pass rolling process, the cold rolled steel sheet after the intermediate annealing process is subjected to skin pass rolling to obtain a base sheet of a non-oriented electrical steel sheet. Specifically, the cold rolled steel sheet after the intermediate annealing process is rolled (cold rolling) at room temperature in the atmosphere. For the skin pass rolling here, for example, a reverse rolling mill such as the Sendzimir rolling mill described above, or a tandem rolling mill is used. By the skin pass rolling, a non-oriented electrical steel sheet (after skin pass rolling and before finish annealing) is obtained.

[0088] In skin pass rolling, rolling is performed without performing annealing treatment in between. For example, when performing skin pass rolling in multiple passes with reverse rolling, multiple passes are performed without annealing treatment between passes. Skin pass rolling may be performed in only one pass using a reverse rolling mill. In addition, when performing skin pass rolling using a tandem rolling mill, rolling is performed continuously in multiple passes (passes at each rolling stand).

[0089] 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 once reduced by intermediate annealing. Then, skin pass rolling is performed. In this way, the strain excessively introduced by cold rolling is reduced in the intermediate annealing, and the preferential recrystallization of {111} grains in the steel sheet surface is suppressed, and the {411} <011> Then, an appropriate amount of strain is introduced into each crystal grain in the steel sheet during skin pass rolling, creating a state in which grain growth due to bulging is likely to occur during the next process, finish annealing.

[0090] In this embodiment, the reduction ratio RR2 in the skin pass rolling is set to 5 to 20%. Here, the reduction ratio RR2 is defined as follows. Reduction ratio RR2 (%) = (1 - thickness after the final pass of skin pass rolling / thickness before the first pass of skin pass rolling) x 100

[0091] If the reduction ratio RR2 is less than 5%, the amount of strain becomes too small, and the final annealing time required for grain growth due to bulging becomes long. On the other hand, if the reduction ratio RR2 exceeds 20%, the amount of strain becomes too large, and normal grain growth occurs instead of bulging, and the {411} <148> or {111} <112> Therefore, the reduction rate RR2 is set to 5 to 20%.

[0092] The number of passes in the skin pass rolling may be only one pass (that is, only one rolling), or may be multiple passes.

[0093] As described above, a steel sheet having an appropriate chemical composition and subjected to appropriate hot rolling and cold rolling is recrystallized by intermediate annealing, and then skin pass rolling is performed under the above-mentioned conditions, whereby the number average Gs of the GOS value and the α-fiber ratio described above can be obtained. The skin pass rolling performed in this embodiment has a significantly different effect from skin pass rolling performed after finish annealing. A desired structure can be obtained by performing hot rolling, cooling, cold rolling, intermediate annealing, skin pass rolling, and finish annealing in this order under predetermined conditions.

[0094] (finish annealing process) In the final annealing process, the non-oriented electrical steel sheet after the skin-pass rolling process is subjected to final annealing. This final annealing causes bulging, driven by the strain difference for each crystal orientation caused by skin-pass rolling, and the desired {411} <011> The annealing conditions are not particularly limited, and those skilled in the art can set the annealing conditions appropriately while checking the occurrence of bulging. Batch annealing is preferred to achieve adequate and sufficient grain growth by bulging, and examples of such annealing include annealing at 750°C to 900°C for 2 hours or more. 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 by bulging is unlikely to occur sufficiently. In this case, the {411} <011> In addition, if the final annealing temperature T2 (℃) exceeds 900℃, a part of the structure of the steel sheet will transform into austenite, and grain growth due to bulging will not occur, resulting in a decrease in the desired {411} <011> In addition, if the annealing time is less than 2 hours, the grain growth due to bulging may not occur sufficiently depending on the temperature, and the {411} <011> The annealing time for the final annealing is not particularly limited, but since the effect is saturated even if the annealing time exceeds 10 hours, the preferred upper limit is 10 hours.

[0095] The temperature increase rate TR2 up to the final annealing temperature T2 in the final annealing step may be any temperature increase rate known to those skilled in the art, and may be, for example, 40° C. / hour or more and less than 200° C. / hour, but is not limited to this range.

[0096] The heating rate TR2 is determined by the following method. A thermocouple is attached to a steel sheet having the above chemical composition and obtained by carrying out the above steps from hot rolling to skin pass to obtain a sample steel sheet. The sample steel sheet to which the thermocouple is attached is heated, and the time from the start of heating to the time when the temperature reaches the finish annealing temperature T2 is measured. The heating rate TR2 is determined based on the measured time.

[0097] The atmosphere during the final annealing step is not particularly limited. For example, the atmosphere during the final annealing step may be an atmospheric gas (dry) containing 20% ​​H2 by volume with the remainder being N2, or a 100% hydrogen atmosphere. The cooling rate of the steel sheet after the final annealing is not particularly limited. The cooling rate is, for example, 0.05 to 20°C / sec, but is not limited to this range.

[0098] This finish annealing may be performed, for example, following skin pass rolling at a steel sheet manufacturer, but instead of performing finish annealing as the next step after the skin pass rolling step, the steel sheet may be shipped to a core processing manufacturer, where the original sheet of the non-oriented electrical steel sheet after skin pass rolling is punched and / or laminated, and then finish annealing may be performed at an annealing temperature of 750°C to 900°C for an annealing time of 2 hours or more. In this case, it is efficient because it can also be performed as "stress relief annealing" which is generally performed on motor cores at core processing manufacturers or motor manufacturers. Of course, the steel sheet after finish annealing may be punched and / or laminated to form a core member or core shape, and then stress relief annealing may be performed.

[0099] According to the above manufacturing method, the non-oriented electrical steel sheet according to this embodiment (including the case where the non-oriented electrical steel sheet serves as part of a core when punching, lamination, and stress relief annealing are performed) can be manufactured.

[0100] In the manufacturing method according to the present embodiment, for example, shot blasting and / or pickling may be performed after the cooling step and before the cold rolling step among the above manufacturing steps. In shot blasting, shot blasting is performed on the steel sheet after hot rolling to destroy and remove scale formed on the surface of the steel sheet after hot rolling. In pickling, pickling treatment is performed on the steel sheet after hot rolling. For example, hydrochloric acid aqueous solution is used as the pickling bath for the pickling treatment. Scale formed on the surface of the steel sheet is removed by pickling. Shot blasting may be performed after the cooling step and before the cold rolling step, and then pickling may be performed. Also, pickling may be performed after the cooling step and before the cold rolling step, and shot blasting may not be performed. Shot blasting may be performed after the cooling step and before the cold rolling step, and pickling treatment may not be performed. Shot blasting and pickling are optional steps. Therefore, it is not necessary to perform both the shot blasting step and the pickling step.

[0101] (Insulating film formation process) In the method for producing an electrical steel sheet according to the present embodiment, an insulating coating may be formed on the surface of the steel sheet (non-oriented electrical steel sheet) after the final annealing step by coating after the final annealing step. The insulating coating forming step is an optional step. Therefore, coating may not be performed after the final annealing.

[0102] The type of insulating film is not particularly limited. The insulating film may be an organic component or an inorganic component, and the insulating coating may contain an organic component and an inorganic component. Examples of inorganic components include dichromate-boric acid, phosphoric acid, and silica. Examples of organic components include general acrylic, acrylic styrene, acrylic silicon, silicone, polyester, epoxy, and fluorine-based resins. Considering paintability, a preferred resin is an emulsion type resin. An insulating coating that exerts adhesive properties by heating and / or pressing may be applied. Examples of insulating coatings that have adhesive properties include acrylic, phenolic, epoxy, and melamine resins.

[0103] The non-oriented electrical steel sheet, the base sheet of the non-oriented electrical steel sheet, and the cold-rolled steel sheet according to the present embodiment are not limited to the above-mentioned manufacturing method, as long as they have a predetermined chemical composition and the specified items such as crystal orientation are within predetermined ranges.

[0104] The core according to this embodiment is obtained by processing the non-oriented electrical steel sheet according to this embodiment or an original sheet of the non-oriented electrical steel sheet into a core by a known method. For example, the non-oriented electrical steel sheet according to this embodiment can be manufactured by punching and / or laminating. Moreover, a core can be manufactured by punching and / or laminating the original sheet of the non-oriented electrical steel sheet according to this embodiment, and performing finish annealing for 2 hours or more at an annealing temperature of 750° C. or more and 900° C. or less. As described above, the finish annealing in this case can be performed as stress relief annealing that is generally performed on cores.

[0105] In any of the above methods, the non-oriented electrical steel sheet or the original sheet of the non-oriented electrical steel sheet forming the core may be integrated into the core by a known method such as caulking, welding, adhesive, insulating coating with adhesive properties, etc. Examples of the punching and lamination method include a method of punching out the stator together with the rotor as an integral core and laminating it, a method of rotating and stacking the stator punched out as an integral core together with the rotor, and a method of punching out and laminating the steel sheet as a split core by aligning the direction of excellent magnetic properties with the direction of the teeth and / or yoke. EXAMPLES

[0106] Next, the non-oriented electrical steel sheet according to the embodiment of the present disclosure will be specifically described with reference to examples. The examples shown below 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 examples below.

[0107] Molten steel was cast to produce an ingot having the chemical composition shown in Table 1. In Table 1, "Co, etc." indicates the respective contents of Co, Pt, Pb, and Au. The produced ingot was then heated and hot rolled under the conditions shown in Table 2. In this example, the heating temperature of the ingot, which is the starting temperature of rough rolling (i.e., the heating temperature of the steel immediately before rolling), was set as the starting temperature of rolling. 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).

[0108] Here, in order to investigate the texture after cooling, a part of the steel plate was cut off, and the average grain size was measured in a plane parallel to the rolling surface at a depth of 1 / 2 the plate thickness from the surface by the intercept method of JIS G0551 (2020). The measurement results are shown in Table 2.

[0109] Next, the hot-rolled steel sheets were not annealed, but scale was removed by pickling, and cold rolling was performed at a rolling reduction RR1 shown in Table 2. Then, intermediate annealing was performed in an atmosphere consisting of 20% hydrogen and 80% nitrogen by volume, with a heating rate of 15.0°C / sec and intermediate annealing temperature T1 controlled to the temperature shown in Table 2 for 30 seconds.

[0110] Here, in order to investigate the texture of the cold-rolled steel sheet before skin-pass rolling (texture after intermediate annealing), a part of the steel sheet was cut out and the thickness of the cut out test piece was reduced to half. Then, in the measurement area by SEM-EBSD on the processed surface, {hkl} <011> Extract the orientation (within a tolerance of 10°), divide the extracted area by the area of ​​the measurement area, and obtain the α fiber ratio A aα The results are shown in Table 3.

[0111] Next, skin pass rolling was performed at a rolling reduction ratio RR2 shown in Table 2.

[0112] Before the final annealing, in order to investigate the texture of the original sheet of the non-oriented electrical steel sheet after skin-pass rolling (texture after skin-pass rolling), a part of the steel sheet was cut off and the thickness of the cut test piece was reduced to half. Then, in the same manner as described above, the α-fiber ratio A sα Also, {100} <011> Regarding the ODF intensity of the orientation, ODF was created under the above conditions using OIM Analysis 7.3 in the measurement area by SEM-EBSD on the processed surface, and the data of the created ODF was output and the {100} <011> The ODF value of the orientation was taken as the ODF strength. Furthermore, for Gs, the number average value of the GOS value was calculated as Gs by analyzing the SEM-EBSD data with OIM Analysis 7.3. The results are shown in Table 3.

[0113] Next, the steel sheet after skin pass rolling was subjected to finish annealing in a 100% hydrogen atmosphere at a temperature increase rate of 100° C. / hour at the finish annealing temperature T2 shown in Table 2. At this time, the holding time at the finish annealing temperature T2 was 2 hours.

[0114] In order to investigate the texture of the non-oriented electrical steel sheet after final annealing (texture after final annealing), a part of the steel sheet was cut off and the thickness of the cut test piece was reduced to half. <011> The ratios of A411-011 / A411-148 and A411-011 / A100-011 were obtained by observing the measurement areas of the processed surfaces using SEM-EBSD under the measurement conditions described above. <uvw>The maximum intensity in the direction φ1 (°) and {hkl} <011> Regarding Φ (°) (maximum intensity φ1 and Φ) which shows the maximum intensity among the orientations, ODF was created under the above-mentioned conditions using OIM Analysis 7.3 in the measurement area of ​​the processed surface by SEM-EBSD, the data of the created ODF was output, and the maximum intensity φ1 and maximum intensity Φ were determined as the points where the ODF value was maximum within a specific orientation range. In addition, a portion of the steel plate was cut out, and the average grain size was measured in a plane parallel to the rolled surface at a depth of 1 / 2 the plate thickness from the surface using the intercept method of JIS G0551 (2020). The results are shown in Table 3.

[0115] In addition, to investigate the magnetic properties after the final annealing, the magnetic flux density B50 and the iron loss W10 / 400 were measured, and the iron loss deterioration rate of the iron loss W10 / 50 under compressive stress was obtained as an index of stress sensitivity. For the magnetic flux density B50, 55 mm square single sheet magnetic property test samples were taken in two directions, 0° and 45° to the rolling direction, as measurement samples. These two types of samples were then measured, and the value in the 45° direction 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° to the rolling direction was taken as the total circumference average of the magnetic flux density B50 (total circumference). For the iron loss W10 / 400 (45°), the above measurement sample taken in the 45° direction to the rolling direction was used. Furthermore, the iron loss deterioration rate W10 / 50 under compressive stress in the 45° direction was calculated. x Regarding [%], when the iron loss without stress W10 / 50 (45° direction) is W10 / 50(0), and the iron loss under a compressive stress of 10MPa W10 / 50 (45° direction) is W10 / 50(10), the iron loss deterioration rate W is calculated using the following formula: x The measurement results are shown in Table 3. W x ={W10 / 50(10)-W10 / 50(0)} / W10 / 50(0) If the magnetic flux density B50 (all around) is 16.15 T or more, it is determined that the magnetic properties all around are excellent. The magnetic properties in the 45° direction were judged to be excellent if the magnetic flux density B50 (B50(45°)) in the 45° direction to the rolling direction was 1.70 T or more, the iron loss W10 / 400 (W100 / 400(45°) in the 45° direction to the rolling direction was 13.8 W / kg or less, and the iron loss deterioration rate of W10 / 50 under compressive stress in the 45° direction to the rolling direction was 40% or less. Regarding hot brittleness, the number of cracks with a depth (width direction length) of 1 mm or more penetrating the sheet thickness on both side end faces in the sheet width direction was evaluated in the range of 10 m in the rolling direction from the position 10 m in the rolling direction from the longitudinal end of the outermost circumference of the hot rolled sheet coil, 10 m in the rolling direction centered on approximately 1 / 4, 1 / 2, and 3 / 4 positions from the longitudinal end of the outermost circumference of the hot rolled sheet coil, and 10 m in the rolling direction from the position 10 m in the rolling direction from the longitudinal end of the innermost circumference of the coil. Specifically, since the total length of the hot rolled sheet coil was 800 m, the evaluation was performed visually at positions 10 to 20 m, 195 to 205 m, 395 to 405 m, 595 to 605 m, and 780 to 790 m (10 to 20 m from the longitudinal end of the innermost circumference of the coil) in the rolling direction from the longitudinal end of the outermost circumference of the coil. If the number of cracks on both end faces was less than 10, it was marked "Y", and if the number of cracks on either one or both of the end faces was 10 or more, it was marked "N". In this embodiment, the hot-rolled coil was used as the evaluation target for hot brittleness, but when evaluating a steel sheet cut out from a hot-rolled coil, both end faces in the sheet width direction may be observed at five or more different positions in the rolling direction of the steel sheet in the same manner as described above. For example, the observation may be performed in a range of about 1 / 10 of the total length of the steel sheet in the rolling direction, centered on positions of about 1 / 10, 1 / 4, 1 / 2, 3 / 4, and 9 / 10 of the length of the steel sheet in the rolling direction, and the total length of the steel sheet in the rolling direction may be 1 m or more. Regarding cost, when the total amount of Mn, Ni and Cu is less than 2.5%, it is indicated as "Y", and when the total amount of Mn, Ni and Cu is more than 2.5%, it is indicated as "N".

[0116] [Table 1-1]

[0117] [Table 1-2]

[0118] [Table 2-1]

[0119] [Table 2-2]

[0120] [Table 3-1-1]

[0121] [Table 3-1-2]

[0122] [Table 3-2-1]

[0123] [Table 3-2-1]

[0124] The underlines in Tables 1 to 3 indicate conditions that are outside the scope of the present disclosure. The disclosed example has good values ​​for magnetic flux density B50 (all circumference), magnetic flux density B50 (45°), and iron loss W10 / 400 (45°), and shows low stress sensitivity. It is also clear that the disclosed example has no problems with hot brittleness and alloy cost.

[0125] The disclosure of Japanese Patent Application No. 2023-001934 is incorporated herein by reference in its entirety. All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference.< / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw>

Claims

1. 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, 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 The alloy contains 0.400% of Mg, 0% to 0.010% in total of one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd, and has a transformation temperature Ar determined by the following formula (1) when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol. Al content is [sol. Al], and the P content is [P], ３ (°C) is 750 to 1050°C, with the balance being Fe and impurities; When the area ratio of crystal grains of {hkl}<uvw> orientation to the entire field of view when a plane parallel to the rolled surface at a depth of 1 / 2 the sheet thickness from the surface of the steel sheet is measured by SEM-EBSD is expressed as Ahkl-uvw, A411-011 is 15.0% or more, and in the ODF of φ2 = 45°, it has a maximum strength at φ1 = 0 to 10° among φ1 = 0 to 90° and Φ = 20°, and has a maximum strength at Φ = 5 to 35° among φ1 = 0° and Φ = 0 to 90°, A non-oriented electrical steel sheet having an average crystal grain size of 50 μm to 150 μm. Ar ３ (℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.-]-120×([M]+[[[[[[])-46×([[[[[Ni]) ・・・(1)

2. The non-oriented electrical steel sheet according to claim 1, wherein the area ratio of crystal grains of a specific orientation to the entire field of view when a plane parallel to the rolled surface at a depth of 1 / 2 of the sheet thickness from the surface of the steel sheet is measured by the SEM-EBSD satisfies both of the following formulas (2) and (3): A411-011 / A411-148 ≧1.1...(2) A411-011 / A100-011 ≧2.0...(3)

3. 2. The non-oriented electrical steel sheet according to claim 1, wherein the content of one or more elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Au, and Cu is less than 2.50% in total.

4. 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, 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 The alloy contains 0.400% of Mg, 0% to 0.010% in total of one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd, and has a transformation temperature Ar determined by the following formula (1) when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol. Al content is [sol. Al], and the P content is [P], ３ (°C) is 750 to 1050°C, with the balance being Fe and impurities; The area ratio A of crystal grains having α-fiber crystal orientation to the entire field of view when a surface parallel to the rolled surface at a depth of 1 / 2 the sheet thickness from the steel sheet surface is measured by SEM-EBSD ｓα is 20.0% or more, The ODF intensity in the {100}<011> orientation when the ODF is created by measuring with the SEM-EBSD is 15.0 or less; When the average number of GOS in the entire field of view measured by the SEM-EBSD is defined as Gs, the non-oriented electrical steel sheet has a Gs of 0.8 or more and 3.0 or less. Ar ３ (℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.-]-120×([M]+[[[[[[])-46×([[[[[Ni]) ・・・(1)

5. A core comprising the non-oriented electrical steel sheet according to any one of claims 1 to 3.

6. A core comprising the base sheet of the non-oriented electrical steel sheet according to claim 4.

7. A cold-rolled steel sheet used for producing 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, 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, 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 The alloy contains 0.400% of Mg, 0% to 0.010% in total of one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd, and has a transformation temperature Ar determined by the following formula (1) when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol. Al content is [sol. Al], and the P content is [P], ３ (°C) is 750 to 1050°C, with the balance being Fe and impurities; The area ratio A of crystal grains having α-fiber crystal orientation to the entire field of view when a surface parallel to the rolled surface at a depth of 1 / 2 the sheet thickness from the steel sheet surface is measured by SEM-EBSD ａα A cold-rolled steel sheet having a C content of 15.0% or more. Ar ３ (℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.-]-120×([M]+[[[[[[])-46×([[[[[Ni]) ・・・(1)

8. 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, 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 The alloy contains 0.400% of Mg, 0% to 0.010% in total of one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd, and has a transformation temperature Ar determined by the following formula (1) when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol. Al content is [sol. Al], and the P content is [P], ３ a hot rolling process of hot rolling a steel material having a chemical composition in which the temperature (°C) is 750 to 1050°C and the balance is Fe and impurities to obtain a hot rolled steel sheet; A cooling process for cooling the hot-rolled steel sheet after the hot rolling process; A cold rolling process of cold rolling the hot rolled steel sheet after the cooling process to obtain a cold rolled steel sheet; An intermediate annealing process for performing intermediate annealing on the cold-rolled steel sheet; a skin pass rolling process in which the cold rolled steel sheet after the intermediate annealing process is subjected to skin pass rolling to obtain a base sheet of a non-oriented electrical steel sheet; a finish annealing process for performing finish annealing on the original sheet of the non-oriented electrical steel sheet after the skin pass rolling process; having In the hot rolling step, the starting temperature of rolling is Ar ３ Temperature +20°C or more, rolling completion temperature is Ar ３ Below temperature, the first Ar ３ The rolling reduction rate during the period until the temperature is passed is 15% or more, and the first Ar ３ The first Ar ３ Rolling is performed so that the reduction ratio during the period until the temperature reaches +20°C is 10% or more. In the cooling step, cooling is started 0.10 seconds or more after the final pass of finish rolling, and after 3 seconds, the cooling is performed at 300° C. or higher with Ar. ３ The temperature is set to -20°C or lower. The reduction ratio in the skin pass rolling process is 5 to 20%, The method for producing a non-oriented electrical steel sheet according to claim 1, wherein in the finish annealing step, the annealing temperature is 750° C. or higher and 900° C. or lower, and the annealing time is 2 hours or longer. Ar ３ (℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.-]-120×([M]+[[[[[[])-46×([[[[[Ni]) ・・・(1)

9. 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, 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 The alloy contains 0.400% of Mg, 0% to 0.010% in total of one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd, and has a transformation temperature Ar determined by the following formula (1) when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol. Al content is [sol. Al], and the P content is [P], ３ a hot rolling process of hot rolling a steel material having a chemical composition in which the temperature (°C) is 750 to 1050°C and the balance is Fe and impurities to obtain a hot rolled steel sheet; A cooling process for cooling the hot-rolled steel sheet after the hot rolling process; A cold rolling process of cold rolling the hot rolled steel sheet after the cooling process to obtain a cold rolled steel sheet; An intermediate annealing process for performing intermediate annealing on the cold-rolled steel sheet; a skin pass rolling process in which the cold rolled steel sheet after the intermediate annealing process is subjected to skin pass rolling to obtain a base sheet of a non-oriented electrical steel sheet; having In the hot rolling step, the starting temperature of rolling is Ar ３ Temperature +20°C or more, rolling completion temperature is Ar ３ Below temperature, the first Ar ３ The rolling reduction rate during the period until the temperature is passed is 15% or more, and the first Ar ３ The first Ar ３ Rolling is performed so that the reduction ratio during the period until the temperature reaches +20°C is 10% or more. In the cooling step, cooling is started 0.10 seconds or more after the final pass of finish rolling, and after 3 seconds, the cooling is performed at 300° C. or higher with Ar. ３ The temperature is set to -20°C or lower. The method for producing an original sheet for a non-oriented electrical steel sheet according to claim 4, wherein a reduction rate in the skin pass rolling step is 5 to 20%. Ar ３ (℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.-]-120×([M]+[[[[[[])-46×([[[[[Ni]) ・・・(1)

10. The method for producing an original sheet for a non-oriented electrical steel sheet according to claim 8 or claim 9, wherein, in the cooling step, the average crystal grain size of the hot-rolled steel sheet after the cooling step is set to 3 to 10 μm.

11. The method for producing the non-oriented electrical steel sheet according to claim 8 or the base sheet for the non-oriented electrical steel sheet according to claim 9, wherein the cold rolling step has a rolling reduction of 75 to 95%.

12. The method for producing a non-oriented electrical steel sheet according to claim 8 or a precursor for a non-oriented electrical steel sheet according to claim 9, wherein the intermediate annealing step is performed at an annealing temperature of 900° C. or less.

13. 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, 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 The alloy contains 0.400% of Mg, 0% to 0.010% in total of one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd, and has a transformation temperature Ar determined by the following formula (1) when the C content is [C], the Mo content is [Mo], the Cr content is [Cr], the Mn content is [Mn], the Ni content is [Ni], the Cu content is [Cu], the Si content is [Si], the sol. Al content is [sol. Al], and the P content is [P], ３ a hot rolling process of hot rolling a steel material having a chemical composition in which the temperature (°C) is 750 to 1050°C and the balance is Fe and impurities to obtain a hot rolled steel sheet; A cooling process for cooling the hot-rolled steel sheet after the hot rolling process; A cold rolling process of cold rolling the hot rolled steel sheet after the cooling process to obtain a cold rolled steel sheet; An intermediate annealing process for performing intermediate annealing on the cold-rolled steel sheet; having In the hot rolling step, the starting temperature of rolling is Ar ３ Temperature +20°C or more, rolling completion temperature is Ar ３ Below temperature, the first Ar ３ The rolling reduction rate during the period until the temperature is passed is 15% or more, and the first Ar ３ The first Ar ３ Rolling is performed so that the reduction ratio during the period until the temperature reaches +20°C is 10% or more. In the cooling step, cooling is started 0.10 seconds or more after the final pass of finish rolling, and after 3 seconds, the cooling is performed at 300° C. or higher with Ar. ３ The method for producing a cold-rolled steel sheet according to claim 7, wherein the temperature is −20° C. or lower. Ar ３ (℃)=1020-325×[C]+33×[Si]+287×[P]+80×[sol.-]-120×([M]+[[[[[[])-46×([[[[[Ni]) ・・・(1)

14. The method for producing a cold rolled steel sheet according to claim 13, wherein, in the cooling step, the average crystal 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, wherein the rolling reduction in the cold rolling step is 75 to 95%.

16. The method for producing a cold rolled steel sheet according to claim 13 or 14, wherein the intermediate annealing step is performed at an annealing temperature of 900° C. or less.

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