Non-oriented electromagnetic steel sheet and method for manufacturing the same

Abstract

The non-oriented electromagnetic steel sheet has a prescribed chemical composition so as to satisfy, when the total area is set as S tot , the area of the {411} oriented grains is set as S 411 , the area of the oriented grains having a Taylor factor M higher than 2.8 is set as S tyl , the total area of the oriented grains having a Taylor factor M of 2.8 or less is set as S tra , the average KAM value of the {411} oriented grains is set as K 411 , the average KAM value of the oriented grains having a Taylor factor M higher than 2.8 is set as K tyl , 0.20≦S tyl / S tot ≦0.85, 0.05≦S 411 / S tot ≦0.80, S 411 / S tra ≧0.50, K 411 / K tyl ≦0.990.

Description

Technical Field

[0001] This invention relates to non-oriented electromagnetic steel sheets and their manufacturing methods.

[0002] This application claims priority based on Japan Patent Application No. 2021-046056 filed on March 19, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] Non-oriented electromagnetic steel sheets are used, for example, in the cores of motors. For non-oriented electromagnetic steel sheets, excellent magnetic properties are required in the direction parallel to the surface of the sheet, such as low iron loss and high magnetic flux density.

[0004] Therefore, it is advantageous to control the texture of the steel sheet in a manner in which the easy magnetization axis (<100> orientation) of the crystal is consistent in the direction within the sheet surface. Regarding such texture control, techniques for controlling {100} orientation, {110} orientation, {111} orientation, etc., as described in Patent Documents 1-5, are widely disclosed.

[0005] Various methods can be conceived for controlling texture, among which the technique of flexibly utilizing strain-induced grain growth exists. In strain-induced grain growth under specific conditions, the aggregation of {111} orientations that do not have an easy magnetization axis in the in-plane direction can be suppressed, thus it is effectively and flexibly applied in non-oriented electromagnetic steel sheets. These techniques have also been disclosed in patent documents 6-10, etc.

[0006] However, while existing methods can suppress the aggregation of the {111} orientation, the {110}<001> orientation (hereinafter referred to as the Gaussian orientation) still grows. The Gaussian orientation exhibits superior magnetic properties in one direction compared to the {111} orientation, but the magnetic properties show almost no improvement in integer averaging. Therefore, there is a problem that superior magnetic properties in integer averaging cannot be obtained using conventional methods.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2017-193754

[0010] Patent Document 2: Japanese Patent Application Publication No. 2011-111658

[0011] Patent Document 3: International Publication No. 2016 / 148010

[0012] Patent Document 4: Japanese Patent Application Publication No. 2018-3049

[0013] Patent Document 5: International Publication No. 2015 / 199211

[0014] Patent Document 6: Japanese Patent Application Publication No. 8-143960

[0015] Patent Document 7: Japanese Patent Application Publication No. 2002-363713

[0016] Patent Document 8: Japanese Patent Application Publication No. 2011-162821

[0017] Patent Document 9: Japanese Patent Application Publication No. 2013-112853

[0018] Patent Document 10: Japanese Patent No. 4029430 Summary of the Invention

[0019] The technical problem that the invention aims to solve

[0020] In view of the above-mentioned problems, the present invention aims to provide a non-oriented electromagnetic steel sheet that can obtain excellent magnetic properties on an integer average basis and a method for manufacturing the same.

[0021] Technical means for solving technical problems

[0022] The inventors of this invention have studied a technique for flexibly utilizing strain-induced grain growth to form a preferred texture for non-oriented electromagnetic steel sheets. It was noted that {411}<uvw> oriented grains (hereinafter referred to as {411} oriented) are also grains that are difficult to strain-inducing to approximately the same extent as Gaussian oriented grains. That is, in the stage before strain-induced grain growth is induced, by increasing the number of {411} oriented grains compared to Gaussian oriented grains, strain-induced grain growth is achieved, and the {411} oriented grains primarily consume the {111} oriented grains, thus producing a non-oriented electromagnetic steel sheet with {411} oriented as the dominant orientation. Therefore, it is known that if the {411} orientation is used as the dominant orientation, the circumferential average (average in the rolling direction, width direction, direction at 45 degrees relative to the rolling direction, and direction at 135 degrees relative to the rolling direction) magnetic properties are improved.

[0023] Furthermore, the inventors investigated a method to increase the number of {411}-oriented grains compared to Gaussian-oriented grains during the stage prior to strain-induced grain growth. The result was a method using oriented electromagnetic steel sheets, cold-rolling the sheets in the width direction at a specified rolling rate, followed by intermediate annealing and surface finishing.

[0024] Based on this knowledge, the inventors of this invention conducted further and in-depth research, and finally came up with the following inventive solutions. [1]

[0026] One aspect of the present invention provides a non-oriented electromagnetic steel sheet having the following chemical composition:

[0027] By mass%, it contains

[0028] C: Below 0.0100%

[0029] Si: 1.50%–4.00%

[0030] One or more of the elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: the total percentage is less than 2.50%.

[0031] sol.Al: 4.000% or less,

[0032] S: Below 0.0400%

[0033] N: below 0.0100%

[0034] Sn: 0.00%~0.40%

[0035] Sb: 0.00%~0.40%

[0036] P: 0.00%~0.40%

[0037] Cr: 0.000%~0.100%

[0038] B: 0.0000%~0.0050%

[0039] O: 0.0000%~0.0200%, and

[0040] One or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%.

[0041] When the Mn content (mass%) is set to [Mn], the Ni content (mass%) is set to [Ni], the Co content (mass%) is set to [Co], the Pt content (mass%) is set to [Pt], the Pb content (mass%) is set to [Pb], the Cu content (mass%) is set to [Cu], the Au content (mass%) is set to [Au], the Si content (mass%) is set to [Si], and the sol.Al content (mass%) is set to [sol.Al], the following equation (1) is satisfied.

[0042] The remaining part consists of Fe and impurities.

[0043] Furthermore, when observing through EBSD with a surface parallel to the steel plate surface, the total area is set as S. tot Let the area of ​​the {411} oriented grains be S. 411Let S be the area of ​​the orientation grains whose Taylor factor M exceeds 2.8 based on the following equation (2). tyl Let S be the total area of ​​the oriented grains with a Taylor factor M of 2.8 or less. tra The average KAM value of the {411} oriented grains is set as K. 411 The average KAM value of the orientation grains with a Taylor factor M exceeding 2.8 is set as K. tyl When the following equations (3) to (6) are satisfied.

[0044] ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%···(1)

[0045]

[0046] 0.20≦S tyl / S tot ≦0.85···(3)

[0047] 0.05≦S 411 / S tot ≦0.80···(4)

[0048] S 411 / S tra ≧0.50···(5)

[0049] K 411 / K tyl ≦0.990···(6)

[0050] Here, in equation (2) λ represents the angle between the stress vector and the sliding direction vector of the crystal, and λ represents the angle between the stress vector and the normal vector of the sliding surface of the crystal. [2]

[0052] Alternatively, the non-oriented electromagnetic steel sheet described above [1] can be further further defined as follows: the average KAM value of the oriented grains with a Taylor factor M of 2.8 or less is set as K. tra When, the following equation (7) is satisfied,

[0053] K 411 / K tra <1.010···(7). [3]

[0055] The non-oriented electromagnetic steel sheet described in [1] or [2] above, further, with the area of ​​the {110} oriented grains set as S 110 When, the following equation (8) is satisfied,

[0056] S 411 / S 110 ≥1.00···(8)

[0057] Here, equation (8) is set to be even if the area ratio S 411 / S 110 The statement that it can be extended to infinity also holds true.

[0058] [4] Alternatively, it can be any of the non-oriented electromagnetic steel sheets described in [1] to [3] above, further wherein the average KAM value of the {110} oriented grains is set to K 110 When, the following equation (9) is satisfied,

[0059] K 411 / K 110 <1.010···(9) [5]

[0061] Other embodiments of the non-oriented electromagnetic steel sheet of the present invention have the following chemical composition:

[0062] By mass%, it contains

[0063] C: Below 0.0100%

[0064] Si: 1.50%–4.00%

[0065] One or more of the elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: the total percentage is less than 2.50%.

[0066] sol.Al: 4.000% or less,

[0067] S: Below 0.0400%

[0068] N: below 0.0100%

[0069] Sn: 0.00%~0.40%

[0070] Sb: 0.00%~0.40%

[0071] P: 0.00%~0.40%

[0072] Cr: 0.000%~0.100%

[0073] B: 0.0000%~0.0050%

[0074] O: 0.0000%~0.0200%, and

[0075] One or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%.

[0076] When the Mn content (mass%) is set to [Mn], the Ni content (mass%) is set to [Ni], the Co content (mass%) is set to [Co], the Pt content (mass%) is set to [Pt], the Pb content (mass%) is set to [Pb], the Cu content (mass%) is set to [Cu], the Au content (mass%) is set to [Au], the Si content (mass%) is set to [Si], and the sol.Al content (mass%) is set to [sol.Al], the following equation (1) is satisfied.

[0077] The remaining part consists of Fe and impurities.

[0078] Furthermore, when observing through EBSD with a surface parallel to the steel plate surface, the total area is set as S. tot Let the area of ​​the {411} oriented grains be S. 411 Let S be the area of ​​the orientation grains whose Taylor factor M exceeds 2.8 based on the following equation (2). tyl Let S be the total area of ​​the oriented grains with a Taylor factor M of 2.8 or less. tra The average KAM value of the {411} oriented grains is set as K. 411 The average KAM value of the orientation grains with a Taylor factor M exceeding 2.8 is set as K. tyl Set the average crystal grain size of the observation area as d. ave The average grain size of the {411} oriented grains is set as d. 411 The average grain size of the orientation grains with a Taylor factor M exceeding 2.8 is set as d. tyl When the following equations (10) to (15) are satisfied,

[0079] ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%···(1)

[0080]

[0081] S tyl / S tot ≦0.70···(10)

[0082] 0.20≦S 411 / S tot ···(11)

[0083] S 411 / Stra ≧0.55···(12)

[0084] K 411 / K tyl ≦1.010···(13)

[0085] d 411 / d ave >1.00···(14)

[0086] d 411 / d tyl >1.00···(15)

[0087] Here, in equation (2) λ represents the angle between the stress vector and the sliding direction vector of the crystal, and λ represents the angle between the stress vector and the normal vector of the sliding surface of the crystal. [6]

[0089] Alternatively, the non-oriented electromagnetic steel sheet described above [5] can be further further defined by setting the average KAM value of the oriented grains with a Taylor factor M of 2.8 or less as K. tra When, the following equation (16) is satisfied.

[0090] K 411 / K tra <1.010···(16). [7]

[0092] Alternatively, the non-oriented electromagnetic steel sheet described in [5] or [6] above, further wherein the average grain size of the oriented grains with a Taylor factor M of 2.8 or less is set to d tra Under these circumstances, the following equation (17) is satisfied.

[0093] d 411 / d tra >1.00···(17) [8]

[0095] Alternatively, it can be any of the non-oriented electromagnetic steel sheets described in [5] to [7] above, further wherein the area of ​​the {110} oriented grains is set as S. 110 When, the following equation (18) is satisfied,

[0096] S 411 / S 110 ≥1.00···(18)

[0097] Here, equation (18) is set to be even if the area ratio S 411 / S 110 The statement that it can be extended to infinity also holds true. [9]

[0099] Alternatively, it can be any of the non-oriented electromagnetic steel sheets described in [5] to [8] above, further wherein the average KAM value of the {110} oriented grains is set to K 110 When, the following equation (19) is satisfied.

[0100] K 411 / K 110 <1.010···(19)

[10]

[0102] Alternatively, it could be any of the non-oriented electromagnetic steel sheets described in [1] to [9] above.

[0103] The chemical components, by mass%, contain...

[0104] From Sn: 0.02% to 0.40%,

[0105] Sb: 0.02%–0.40%, and

[0106] P: Select one or more groups consisting of 0.02% to 0.40%.

[11]

[0108] Alternatively, the non-oriented electromagnetic steel sheet described in any of [1] to

[10] above, wherein the chemical composition, by mass%, contains one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd, totaling 0.0005% to 0.0100%.

[12]

[0110] One aspect of the present invention is a method for manufacturing a non-oriented electromagnetic steel sheet, which is a method for manufacturing a non-oriented electromagnetic steel sheet as described in any one of [1] to [4] above, comprising:

[0111] For oriented electromagnetic steel sheets, a cold rolling process is performed in the width direction at a rolling rate of 20% to 50%.

[0112] The cold-rolled steel sheet is then subjected to an intermediate annealing process at a temperature of 650°C or higher; and

[0113] The steel sheet that has undergone the intermediate annealing is then subjected to a surface finishing rolling process in the same direction as the cold rolling direction at a rolling rate of 5% to 30%.

[0114] The oriented electromagnetic steel sheet has the following chemical composition, which, by mass%, contains:

[0115] C: Below 0.0100%

[0116] Si: 1.50%–4.00%

[0117] One or more of the elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: the total percentage is less than 2.50%.

[0118] sol.Al: 4.000% or less,

[0119] S: Below 0.0400%

[0120] N: below 0.0100%

[0121] Sn: 0.00%~0.40%

[0122] Sb: 0.00%~0.40%

[0123] P: 0.00%~0.40%

[0124] Cr: 0.000%~0.100%

[0125] B: 0.0000%~0.0050%

[0126] O: 0.0000%~0.0200%, and

[0127] One or more of the elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%.

[0128] When the Mn content (mass%) is set to [Mn], the Ni content (mass%) is set to [Ni], the Co content (mass%) is set to [Co], the Pt content (mass%) is set to [Pt], the Pb content (mass%) is set to [Pb], the Cu content (mass%) is set to [Cu], the Au content (mass%) is set to [Au], the Si content (mass%) is set to [Si], and the sol.Al content (mass%) is set to [sol.Al], the following equation (1) is satisfied.

[0129] The remaining portion consists of Fe and impurities;

[0130] ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%···(1).

[13]

[0132] The manufacturing method of the non-oriented electromagnetic steel sheet in other embodiments of the present invention is the manufacturing method of the non-oriented electromagnetic steel sheet described in any one of [5] to [9] above.

[0133] The non-oriented electromagnetic steel sheet described in any of [1] to [4] above is subjected to heat treatment at a temperature of 700°C to 950°C for 1 to 100 seconds.

[14]

[0135] Other embodiments of the non-oriented electromagnetic steel sheet of the present invention have the following chemical composition:

[0136] By mass%, it contains

[0137] C: Below 0.0100%

[0138] Si: 1.50%–4.00%

[0139] One or more of the elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: the total percentage is less than 2.50%.

[0140] sol.Al: 4.000% or less,

[0141] S: Below 0.0400%

[0142] N: below 0.0100%

[0143] Sn: 0.00%~0.40%

[0144] Sb: 0.00%~0.40%

[0145] P: 0.00%~0.40%

[0146] Cr: 0.000%~0.100%

[0147] B: 0.0000%~0.0050%

[0148] O: 0.0000%~0.0200%, and

[0149] One or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%.

[0150] When the Mn content (mass%) is set to [Mn], the Ni content (mass%) is set to [Ni], the Co content (mass%) is set to [Co], the Pt content (mass%) is set to [Pt], the Pb content (mass%) is set to [Pb], the Cu content (mass%) is set to [Cu], the Au content (mass%) is set to [Au], the Si content (mass%) is set to [Si], and the sol.Al content (mass%) is set to [sol.Al], the following equation (1) is satisfied.

[0151] The remaining part consists of Fe and impurities.

[0152] Furthermore, when observing through EBSD with a surface parallel to the steel plate surface, the total area is set as S. tot Let the area of ​​the {411} oriented grains be S. 411 Let S be the area of ​​the orientation grains whose Taylor factor M exceeds 2.8 based on the following equation (2). tyl Let S be the total area of ​​the oriented grains with a Taylor factor M of 2.8 or less. tra Set the average crystal grain size of the observation area as d. ave The average grain size of the {411} oriented grains is set as d. 411 The average grain size of the orientation grains with a Taylor factor M exceeding 2.8 is set as d. tyl When, the following equations (20) to (24) are satisfied,

[0153] ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%···(1)

[0154]

[0155] S tyl / S tot <0.55···(20)

[0156] S 411 / S tot >0.30···(21)

[0157] S 411 / S tra ≧0.60···(22)

[0158] d 411 / d ave ≧0.95···(23)

[0159] d 411 / d tyl ≧0.95···(24)

[0160] Here, in equation (2) λ represents the angle between the stress vector and the sliding direction vector of the crystal, and λ represents the angle between the stress vector and the normal vector of the sliding surface of the crystal.

[15]

[0162] Alternatively, the non-oriented electromagnetic steel sheet described above

[14] can be further further defined by setting the average grain size of the oriented grains with a Taylor factor M of 2.8 or less as d. traWhen, the following equation (25) is satisfied.

[0163] d 411 / d tra ≧0.95···(25)

[16]

[0165] In another embodiment of the present invention, the non-oriented electromagnetic steel sheet is heat-treated at a temperature of 950°C to 1050°C for 1 to 100 seconds, or at a temperature of 700°C to 900°C for more than 1000 seconds.

[0166] Invention Effects

[0167] According to the above-described solution of the present invention, it is possible to provide a non-oriented electromagnetic steel sheet with excellent magnetic properties on an integer average and a method for manufacturing the same. Detailed Implementation

[0168] The embodiments of the present invention will now be described. One embodiment of the non-oriented electromagnetic steel sheet uses an oriented electromagnetic steel sheet having the chemical composition described later as material, and is manufactured through a cold rolling process, an intermediate annealing process, and a surface smoothing process, involving cold rolling in the width direction of the oriented electromagnetic steel sheet. Another embodiment of the present invention uses a non-oriented electromagnetic steel sheet manufactured through a cold rolling process, an intermediate annealing process, a surface smoothing process, and a first heat treatment process, involving cold rolling in the width direction of the oriented electromagnetic steel sheet. Furthermore, another embodiment of the present invention uses a non-oriented electromagnetic steel sheet manufactured through a cold rolling process, an intermediate annealing process, a surface smoothing process, a first heat treatment process performed as needed, and a second heat treatment process, involving cold rolling in the width direction of the oriented electromagnetic steel sheet.

[0169] Following surface-rolling and subsequent heat treatment (first and / or second heat treatment), the steel sheet undergoes strain-induced grain growth, followed by normal grain growth. Strain-induced grain growth and normal grain growth can be performed in either the first or second heat treatment step. The surface-rolled steel sheet is considered the original sheet after both strain-induced and normal grain growth. Furthermore, the surface-rolled steel sheet is considered the original sheet after normal grain growth. Hereinafter, regardless of heat treatment, the surface-rolled steel sheet, the strain-induced grain growth steel sheet, and the normal grain growth steel sheet will all be described as non-oriented electromagnetic steel sheets.

[0170] Furthermore, in this embodiment, by increasing the number of {411}-oriented grains (hereinafter referred to as {411}-oriented grains) than the number of {110}-oriented grains in the metallographic structure of the steel sheet before surface rolling, the {411}-oriented grains are further increased in the subsequent heat treatment process, thereby improving the overall magnetic properties. Alternatively, the {411}-oriented grains can be added before surface rolling in addition to the processes described above.

[0171] First, the chemical composition of the material used in the non-oriented electromagnetic steel sheet and its manufacturing method in this embodiment, namely the oriented electromagnetic steel sheet, will be described. The chemical composition does not change during rolling or heat treatment; therefore, the chemical composition of the oriented electromagnetic steel sheet as the material is the same as that of the non-oriented steel sheet obtained through each process. In the following description, the unit for the content of each element contained in the non-oriented electromagnetic steel sheet or steel, i.e., "%", is expressed as "mass %" unless otherwise specified. The non-oriented electromagnetic steel sheet and its material in this embodiment, namely the oriented electromagnetic steel sheet, have the following chemical composition: C: 0.0100% or less, Si: 1.50% to 4.00%, one or more selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: total less than 2.50%, sol.Al: 4.000% or less, S: 0.0400% or less, N: 0.0100% or less, Sn: 0.00% to 0.40%. %, Sb: 0.00% to 0.40%, P: 0.00% to 0.40%, Cr: 0.000% to 0.100%, B: 0.0000% to 0.0050%, O: 0.0000% to 0.0200%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%, with the remainder consisting of Fe and impurities. Furthermore, when the Mn content (mass%) is set to [Mn], the Ni content (mass%) to [Ni], the Co content (mass%) to [Co], the Pt content (mass%) to [Pt], the Pb content (mass%) to [Pb], the Cu content (mass%) to [Cu], the Au content (mass%) to [Au], the Si content (mass%) to [Si], and the sol.Al content (mass%) to [sol.Al], the following condition is met: ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%. Examples of impurities include substances contained in raw materials such as ores or waste, and substances contained in the manufacturing process.

[0172] In addition, instead of oriented electromagnetic steel sheets, single crystals can be generated in steel sheets with the above chemical composition, and the grains with Gaussian orientation can be cut and used as materials.

[0173] (C: below 0.0100%)

[0174] Carbon (C) increases iron loss or causes magnetic aging. Therefore, the lower the C content, the better. This phenomenon is significant when the C content is above 0.0100%. Therefore, the C content is set below 0.0100%. The lower limit of the C content is not particularly limited, but based on the cost of decarburization treatment during refining, it is preferable to set the C content above 0.0005%.

[0175] (Si: 1.50%–4.00%)

[0176] Si increases electrical resistance, reduces eddy current losses, lowers iron losses, increases the yield ratio, and improves the workability of the core. These effects are not fully realized when the Si content is less than 1.50%. Therefore, the Si content is 1.50% or higher. On the other hand, when the Si content is higher than 4.00%, the magnetic flux density decreases, and the excessive increase in hardness leads to reduced workability or difficulty in cold rolling. Therefore, the Si content is set below 4.00%.

[0177] (Selecting one or more from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: total less than 2.50%)

[0178] These elements are austenite phase (γ phase) stabilizing elements. If they are present in large quantities, a ferrite-austenite phase transformation (hereinafter referred to as α-γ phase transformation) will occur during the heat treatment of the steel sheet. It is believed that the effect of the non-oriented electromagnetic steel sheet of this embodiment is achieved by controlling the area and area ratio of specific crystal orientations in a cross-section parallel to the surface of the steel sheet. However, during the α-γ phase transformation, the aforementioned area and area ratio change significantly due to the phase transformation, making it difficult to obtain the specified area ratio. Therefore, the total content of one or more elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au is limited to less than 2.50%. The total content is preferably less than 2.00%, more preferably less than 1.50%. The lower limit of the total content of these elements is not particularly limited, but from a cost perspective, it is preferable to set it to 0.0001% or more.

[0179] Furthermore, as a condition for no α-γ phase transition to occur, the following condition must be met. That is, when the Mn content (mass%) is set to [Mn], the Ni content (mass%) is set to [Ni], the Co content (mass%) is set to [Co], the Pt content (mass%) is set to [Pt], the Pb content (mass%) is set to [Pb], the Cu content (mass%) is set to [Cu], the Au content (mass%) is set to [Au], the Si content (mass%) is set to [Si], and the sol.Al content (mass%) is set to [sol.Al], the following equation (1) is satisfied.

[0180] ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%···(1)

[0181] (sol.Al: 4.000% or less)

[0182] Sol.Al increases electrical resistance, reduces eddy current losses, and lowers iron losses. Sol.Al also contributes to increasing the relative magnitude of magnetic flux density B50 relative to saturation magnetic flux density. Here, magnetic flux density B50 refers to the magnetic flux density in a magnetic field of 5000 A / m. These effects are not sufficiently obtained when the sol.Al content is less than 0.0001%. Furthermore, Al also promotes desulfurization in steelmaking. Therefore, the sol.Al content is preferably 0.0001% or more. More preferably, it is 0.001% or more, and even more preferably, it is 0.300% or more. On the other hand, when the sol.Al content is higher than 4.000%, the magnetic flux density decreases, the yield ratio decreases, and the workability decreases. Therefore, the sol.Al content is set to 4.000% or less. The sol.Al content is preferably 2.500% or less, and more preferably 1.500% or less.

[0183] (S: below 0.0400%)

[0184] Sulfur (S) is not an essential element and is present in steel as an impurity. S, through the precipitation of fine MnS, hinders recrystallization and grain growth during annealing. Therefore, a lower S content is preferable. This hindering of recrystallization and grain growth leads to increased iron loss and decreased magnetic flux density, which is significant when the S content is above 0.0400%. Therefore, the S content is set to 0.0400% or less. The S content is preferably 0.0200% or less, and more preferably 0.0100% or less. The lower limit of the S content is not particularly limited, but considering the cost of desulfurization treatment during refining, the S content is preferably set to 0.0003% or more.

[0185] (N: below 0.0100%)

[0186] Like C, nitrogen (N) deteriorates magnetic properties, so a lower N content is better. Therefore, the N content is set to below 0.0100%. While there is no particular limitation on the lower limit of the N content, it is preferably above 0.0010% based on the cost of denitrification treatment during refining.

[0187] (Sn: 0.00% to 0.40%, Sb: 0.00% to 0.40%, P: 0.00% to 0.40%)

[0188] Excessive levels of Sn, Sb, and P will cause the steel to become embrittled. Therefore, the Sn and Sb contents are both set below 0.40%, and the P content is set below 0.40%.

[0189] On the other hand, Sn and Sb improve the texture after cold rolling and recrystallization, increasing its magnetic flux density. P helps ensure the hardness of the recrystallized steel sheet. Therefore, these elements can be included as needed. When imparting further effects such as magnetic properties, it is preferable to include one or more elements selected from the group consisting of 0.02% to 0.40% Sn, 0.02% to 0.40% Sb, and 0.02% to 0.40% P.

[0190] (Selecting one or more from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%)

[0191] Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd react with sulfur (S) in molten steel during its production to form sulfides, sulfur oxides, or both as precipitates. Hereinafter, Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd are sometimes collectively referred to as "coarse precipitate-forming elements." The particle size of precipitates from coarse precipitate-forming elements is approximately 1 μm to 2 μm, significantly larger than the particle size (approximately 100 nm) of fine precipitates such as MnS, TiN, and AlN. Therefore, these fine precipitates adhere to the precipitates from coarse precipitate-forming elements and are less likely to hinder grain growth in strain-induced grain growth. Therefore, these elements can also be included. To fully achieve the above effects, the total content of these elements is preferably set to 0.0005% or more.

[0192] On the other hand, if the total content of these elements exceeds 0.0100%, the total amount of sulfides or sulfur oxides, or both, becomes excessive, hindering grain growth in strain-induced grain growth. Therefore, the total content of elements that generate coarse precipitates is set to less than 0.0100%.

[0193] (Cr: 0.000%~0.100%)

[0194] Cr combines with oxygen in steel to form Cr₂O₃. This Cr₂O₃ helps improve the texture. Therefore, it can be included in the steel. To achieve the above-mentioned effects, it is preferable to set the Cr content to 0.001% or more.

[0195] On the other hand, when the Cr content is higher than 0.100%, C r2 O3 hinders grain growth during annealing, resulting in finer grain sizes and increased iron loss. Therefore, the Cr content is set to below 0.100%.

[0196] (B: 0.0000%~0.0050%)

[0197] A small amount of B helps improve the texture. Therefore, B can be included. To achieve the above-mentioned effects, it is preferable to set the B content to 0.0001% or more.

[0198] On the other hand, if the boron content is higher than 0.0050%, the boron compounds hinder grain growth during annealing, resulting in finer grain sizes and increased iron loss. Therefore, the boron content is set to below 0.0050%.

[0199] (O: 0.0000%~0.0200%)

[0200] O combines with Cr in steel to form Cr2O3. This Cr2O3 helps improve the texture. Therefore, it is also possible to include O. To achieve the above effects, it is preferable to set the O content to 0.0010% or more.

[0201] On the other hand, when the O content is higher than 0.0200%, Cr2O3 hinders grain growth during annealing, resulting in finer crystal grains and increased iron loss. Therefore, the O content is set below 0.0200%.

[0202] Next, the thickness of the non-oriented electromagnetic steel sheet in this embodiment will be explained. The thickness (sheet thickness) of the non-oriented electromagnetic steel sheet in this embodiment is preferably 0.10 mm to 0.28 mm. When the thickness exceeds 0.28 mm, excellent high-frequency iron loss may not be obtained. Therefore, the thickness is preferably 0.28 mm or less. If the thickness is less than 0.10 mm, the effects of magnetic flux leakage from the surface of the non-oriented electromagnetic steel sheet increase, resulting in poorer magnetic properties. Furthermore, if the thickness is less than 0.10 mm, it is difficult to pass through the annealing production line, increasing the number of non-oriented electromagnetic steel sheets required for a given core size, potentially leading to reduced productivity and increased manufacturing costs due to the increased number of processes. Therefore, the thickness is preferably 0.10 mm or more. A thickness of 0.20 mm to 0.25 mm is more preferred.

[0203] Next, the metallographic structure of the non-oriented electromagnetic steel sheet of this embodiment will be described. The non-oriented electromagnetic steel sheet of each embodiment will be determined below by the metallographic structure after surface rolling, the metallographic structure after the first heat treatment, and the metallographic structure after the second heat treatment.

[0204] First, the specific metallographic structure and its determination method will be explained. In this embodiment, the metallographic structure is determined by a cross-section parallel to the surface of the steel plate, and is therefore determined through the following steps.

[0205] First, grinding is performed with the center of the plate thickness exposed on the surface. This ground surface (parallel to the surface of the steel plate) is then subjected to EBSD (Electron Back Scattering Diffraction) at a depth of 2500 μm. 2 The above areas were observed. The total observed area is 2500 μm. 2 The above can be divided into several small units and several locations. The step interval during measurement is preferably 50-100 nm. From the EBSD observation data, the following types of areas, KAM (Kernel Average Misorientation) values, and average crystal grain sizes are obtained through conventional methods.

[0206] S tot Total area (observation area)

[0207] S tyl The total area of ​​orientation grains whose Taylor factor M exceeds 2.8 according to the following equation (2) is:

[0208] S tra The total area of ​​oriented grains with a Taylor factor M of 2.8 or less according to the following equation (2)

[0209] S 411 Total area of ​​{411} oriented grains

[0210] S 110 Total area of ​​{110} oriented grains

[0211] K tyl According to the following equation (2), the Taylor factor M exceeds 2.8 for the average KAM value of the orientation grains.

[0212] K tra According to the following equation (2), the average KAM value of the orientation grains with a Taylor factor M of 2.8 or less is...

[0213] K 411 Average KAM value of {411} oriented grains

[0214] K110 Average KAM value of {110} oriented grains

[0215] d ave Average crystal grain size in the observation area

[0216] d 411 Average grain size of {411} oriented grains

[0217] d tyl According to the following equation (2), the average grain size of the orientation grains is greater than 2.8.

[0218] d tra According to the following equation (2), the average grain size of the oriented grains is less than 2.8.

[0219] Here, the orientation margin of the grains is set to 15°. Furthermore, when oriented grains appear below, the orientation margin is also set to 15°.

[0220] Here, the Taylor factor M is determined according to the following equation (2).

[0221]

[0222] The angle between the stress vector and the crystal's sliding direction vector

[0223] λ: The angle between the stress vector and the normal vector of the crystal's sliding surface.

[0224] The Taylor factor M mentioned above is assumed to be caused by the sliding deformation of the crystal with sliding surface {110} and sliding direction <111>. It is the Taylor factor when compressive deformation in the direction of plate thickness occurs in the plane strain in the plane parallel to the plate thickness direction and the rolling direction. Hereinafter, unless otherwise specified, the average value obtained for all crystallographically equivalent crystals in the Taylor factor according to equation (2) will be simply referred to as the "Taylor factor".

[0225] Next, in the following embodiments 1 to 3, the above-described characteristics of area, KAM value, and average crystal grain size are specified.

[0226] (Implementation Method 1)

[0227] First, the metallographic structure of the non-oriented electromagnetic steel sheet after surface smoothing is described. This metallographic structure accumulates sufficient strain to induce strain-induced grain growth, and can be positioned in the initial stage before strain-induced grain growth occurs. The characteristics of the metallographic structure of the steel sheet after surface smoothing are roughly determined by the orientation of the grains developed as the target orientation, and the conditions related to the strain that has accumulated sufficiently to induce strain-induced grain growth.

[0228] In the non-oriented electromagnetic steel sheet of this embodiment, the area of ​​each oriented grain satisfies the following equations (3) to (5).

[0229] 0.20≦S tyl / S tot ≦0.85···(3)

[0230] 0.05≦S 411 / S tot ≦0.80···(4)

[0231] S 411 / S tra ≧0.50···(5)

[0232] S tyl This refers to the abundance of orientations with sufficiently large Taylor factors. In strain-induced grain growth, orientations where strain accumulation is difficult due to a smaller processing Taylor factor preferentially grow while simultaneously eroding orientations where strain accumulation is greater due to a larger processing Taylor factor. Therefore, in order to develop specific orientations through strain-induced grain growth, S... tyl A certain quantity is required. In this embodiment, S is the area ratio relative to the total area. tyl / S tot Regulations will be established to specify the area ratio S tyl / S tot Set to 0.20 or higher. Area ratio S tyl / S tot When the area ratio is less than 0.20, the crystal orientation desired by strain-induced grain growth cannot be sufficiently developed. Preferably, the area ratio S... tyl / S tot The value is 0.30 or higher, and more preferably 0.50 or higher.

[0233] Area ratio S tyl / S tot The upper limit is related to the amount of {411} oriented grains that should be developed in the strain-induced grain growth process, as explained below, but this condition is not simply determined by the ratio of preferentially grown orientations to eroded orientations. First, as described later, the area ratio S of {411} oriented grains that should be developed through strain-induced grain growth... 411 / S tot If it is above 0.05, then the area ratio must be greater than S. tyl / S tot It is below 0.95. However, if the area is greater than S... tyl / S tot If the amount of [something] is too large, then due to the relationship with strain described later, preferential growth of {411} oriented grains will not occur. The relationship with strain will be described in detail later, but in this embodiment, the area ratio S [is used].tyl / S tot It is below 0.85. Preferably, the area ratio S tyl / S tot The value is 0.75 or less, and more preferably 0.70 or less.

[0234] In the subsequent strain-induced grain growth process, {411} oriented grains are preferentially grown. The {411} orientation is one of the orientations with a sufficient Taylor factor and low accumulation of processing-induced deformation, making it a preferred orientation for growth in the strain-induced grain growth process. In this embodiment, the presence of {411} oriented grains is essential. In this embodiment, the area ratio of the {411} oriented grains is set to S... 411 / S tot Set to 0.05 or higher. The area ratio S of {411} oriented grains. 411 / S tot If the area ratio is less than 0.05, then the {411} oriented grains cannot develop sufficiently through subsequent strain-induced grain growth. Preferably, the area ratio S... 411 / S tot The value is 0.10 or higher, and more preferably 0.20 or higher.

[0235] Area ratio S 411 / S tot The upper limit is determined based on the amount of crystal orientation grains that should be devoured during strain-induced grain growth. In this embodiment, the area ratio S of orientations with a Taylor factor exceeding 2.8 that should be devoured during strain-induced grain growth is [not specified]. tyl / S tot It is above 0.20, thus the area ratio is greater than S. 411 / S tot The value is below 0.80. Among these, the side with a lower presence of {411} oriented grains before strain-induced grain growth has a more significant effect, enabling more developed {411} oriented grains. Considering this, preferably, the area ratio S... 411 / S tot The value is 0.60 or less, preferably 0.50 or less, and even more preferably 0.40 or less.

[0236] As the orientation grains that should be preferentially grown, the {411} orientation grains have been described as the center. However, similar to the {411} orientation grains, there are also a large number of orientation grains with sufficiently small Taylor factors and where strain from processing is difficult to accumulate. These are orientation grains that can preferentially grow in strain-induced grain growth. Among them, the {110} orientation is an orientation that is easy to exist in non-oriented electromagnetic steel sheets. This orientation grain competes with the {411} orientation grains that should be preferentially grown. On the other hand, the easy magnetization axis direction (<100> orientation) in the steel sheet surface of this orientation grain is not as numerous as that of the {411} orientation grains. Therefore, if these orientations develop in strain-induced grain growth, the magnetic properties will deteriorate, which is undesirable. Therefore, in this embodiment, the presence ratio of {411} orientation grains is specified as the orientation that ensures a sufficiently small Taylor factor and where strain from processing is difficult to accumulate.

[0237] In this invention, the area of ​​an oriented grain with a Taylor factor of 2.8 or less that is included in strain-induced grain growth and is considered to compete with the {411} oriented grain is defined as S. tra Moreover, as described in equation (5), the area ratio S 411 / S tra Setting it to 0.50 or higher ensures priority for {411} oriented grain growth. This area ratio S 411 / S tra When the area ratio is less than 0.50, due to strain-induced grain growth, {411} oriented grains cannot develop sufficiently. The preferred area ratio S... 411 / S tra The value should be 0.80 or higher, preferably 0.90 or higher. On the other hand, the area ratio S... 411 / S tra The upper limit does not need to be specifically limited; all orientation grains with a Taylor factor below 2.8 can be {411} orientation grains (S 411 / S tra =1.00).

[0238] Furthermore, in this embodiment, the relationship with {110} oriented grains, known as an orientation that readily grows in strain-induced grain growth, is specifically specified. The {110} orientation is relatively easy to develop in common methods such as increasing the grain size in hot-rolled steel sheets, recrystallizing it through cold rolling, and recrystallizing it through cold rolling at a relatively low rolling rate. It is particularly important to consider in the competition with {411} oriented grains, which should be preferentially grown. If {110} oriented grains develop during strain-induced grain growth, the in-plane anisotropy of the steel sheet becomes very large, which is undesirable. Therefore, in this embodiment, it is preferable that the area ratio S of {411} oriented grains to {110} oriented grains is... 411 / S 110This satisfies equation (8), thereby ensuring the priority of {100} oriented grain growth.

[0239] S 411 / S 110 ≥1.00···(8)

[0240] To more reliably prevent the unintended development of {110} oriented grains due to strain-induced grain growth, an area ratio of S is preferred. 411 / S 110 The value is above 1.00. The preferred area ratio S is... 411 / S 110 A value of 2.00 or higher is preferred, and 4.00 or higher is even more desirable. Area ratio S 411 / S 110 The upper limit does not need to be specifically limited, and the area fraction of {110} oriented grains can also be zero. That is, even if the area ratio is S 411 / S 110 As the earth expands infinitely, equation (8) also holds true.

[0241] In addition to the crystal orientation described above, this embodiment can also obtain even better magnetic properties by combining the strains described below. In this embodiment, as a strain-related requirement, the following equation (6) must be satisfied.

[0242] K 411 / K tyl ≦0.990···(6)

[0243] The strain-related criteria are defined by equation (6). Equation (6) is the ratio of the accumulated strain (average KAM value) of {411} oriented grains to the accumulated strain (average KAM value) of oriented grains with a Taylor factor higher than 2.8. Here, KAM is the orientation difference between adjacent measurement points within the same grain; the KAM value increases at locations with greater strain. From a crystallographic point of view, for example, in the case of compressive deformation in the thickness direction under plane strain in a plane parallel to the thickness direction and the rolling direction, i.e., in the case of simply rolling a steel plate, this KAM value is usually... 411 With K tyl The ratio of K 411 / K tylLess than 1. However, in reality, the strain corresponding to the microscopic crystal orientation is highly diverse, influenced by factors such as the constraints of adjacent grains, precipitates within the grains, and minute deformation variations due to contact with the deformation tools (rolling rolls, etc.). Therefore, it is difficult to represent the purely geometric orientation effect caused by the Taylor factor. Furthermore, even grains with the same orientation can exhibit significant variations due to differences in grain size, grain morphology, the orientation or size of adjacent grains, the state of precipitates, and their position in the thickness direction. Moreover, even within a single grain, the formation of strain distribution near grain boundaries, within grains, and in deformation zones leads to substantial variations in strain distribution.

[0244] Taking these variations into account, in order to obtain excellent magnetic properties in this embodiment, K is... 411 / K tyl Set it below 0.990. If this K 411 / K tyl Above 0.990, the specificity of the region to be encroached upon is lost. Therefore, it is difficult to induce strain-induced grain growth. Preferably, K 411 / K tyl The value is below 0.970, and more preferably below 0.950.

[0245] In the competition with the {411} oriented grains that should be given priority in growth, the relationship with oriented grains with a Taylor factor of 2.8 or less preferably satisfies equation (7).

[0246] K 411 / K tra <1.010···(7)

[0247] To preferentially grow {411} oriented grains, K is preferably used. 411 / K tra Set it to be less than 1.010. This K 411 / K tra K is an indicator related to the competition and cooperation between orientations where strain is difficult to accumulate and there is a possibility of preferential growth. 411 / K tra If the value is above 1.010, the priority of the {411} orientation in strain-induced grain growth cannot be utilized, and the target crystal orientation will not develop. 411 / K tra The preferred value is below 0.970, and even more preferred value is below 0.950.

[0248] In the competition with the {411} oriented grains that should be preferentially grown, the relationship with the {110} oriented grains, like the area, is preferably considered in terms of strain. In this relationship, the ratio KAM of the average KAM values ​​of the {411} oriented grains and the {110} oriented grains is preferably expressed as KAM. 411 / K110 This satisfies equation (9), thereby ensuring the priority of {411} oriented grain growth.

[0249] K 411 / K 110 <1.010···(9)

[0250] To more reliably prevent the unintended development of {110} oriented grains due to strain-induced grain growth, K is preferred. 411 / K 110 It is less than 1.010. K 411 / K 110 The preferred value is below 0.970, and even more preferred value is below 0.950.

[0251] In equation (9), if there are no grains with an orientation equivalent to the denominator, no numerical evaluation is performed on this equation, and it is assumed that the equation is satisfied.

[0252] In the metallographic structure of the non-oriented electromagnetic steel sheet in the post-smooth rolling state of this embodiment, the crystal grain size is not particularly limited. This is because, under the condition that appropriate strain-induced grain growth is induced by the subsequent first heat treatment, the relationship with crystal grain size is not so strong. That is, whether appropriate strain-induced grain growth is induced as a target can be roughly determined, in addition to the chemical composition of the steel sheet, by the relationship between the presence (area) of each crystal orientation and the relationship between the deformation of each orientation.

[0253] If the crystal grain size is very large, strain can induce sufficient grain growth, but this is difficult to achieve within the practical temperature range. Furthermore, if the crystal grain size is very large, it is difficult to avoid deterioration of magnetic properties. Therefore, a practical average crystal grain size is preferably 300 μm or less. More preferably, it is 100 μm or less, even more preferably 50 μm or less, and particularly preferably 30 μm or less. The finer the crystal grain size, the easier it is to identify the development of the desired crystal orientation caused by strain-induced grain growth when the crystal orientation and strain distribution are properly controlled. However, if it becomes too fine, it is difficult to form differences in strain for each crystal orientation due to constraints with adjacent grains during the strain-applied processing described above. From this viewpoint, an average crystal grain size is preferably 3 μm or more, more preferably 8 μm or more, and even more preferably 15 μm or more.

[0254] (Implementation Method 2)

[0255] Next, the metallographic structure of the non-oriented electromagnetic steel sheet after strain-induced grain growth (before the end of strain-induced grain growth) will be described. In this embodiment, the non-oriented electromagnetic steel sheet releases at least a portion of the strain through strain-induced grain growth, and the characteristics of the metallographic structure of the steel sheet after strain-induced grain growth are defined by crystal orientation, strain, and crystal grain size.

[0256] The crystal orientation in this embodiment satisfies the following equations (10) to (12). These specifications differ in numerical range from equations (3) to (5) related to the aforementioned non-oriented electromagnetic steel sheet after surface smoothing. This is because, with strain-induced grain growth, {411} oriented grains preferentially grow, increasing their area, while oriented grains with a Taylor factor exceeding 2.8 are mainly consumed by {411} oriented grains, resulting in a decrease in their area.

[0257] S tyl / S tot ≦0.70···(10)

[0258] 0.20≦S 411 / S tot ···(11)

[0259] S 411 / S tra ≧0.55···(12)

[0260] Area ratio S tyl / S tot The upper limit is determined as one of the parameters representing the extent of strain-induced grain growth. Area ratio S tyl / S tot A value exceeding 0.70 indicates that the grains of orientations with a Taylor factor exceeding 2.8 have not been sufficiently cannibalized, and strain-induced grain growth has not been sufficiently induced. That is, because the development of the {411} orientation grains, which should be well-developed, is insufficient, the magnetic properties are not sufficiently improved. Therefore, in this embodiment, the area ratio S... tyl / S tot Set to 0.70 or below. Preferably, the area ratio S tyl / S tot The value is below 0.60, preferably below 0.50. Area ratio S tyl / S tot The value is preferably smaller, so there is no need to specify a lower limit, and it can also be 0.00.

[0261] Furthermore, in this embodiment, the area ratio S 411 / S tot Set to 0.20 or higher. Area ratio S 411 / S totThe lower limit is determined as one of the parameters representing the extent of strain-induced grain growth, and the area ratio S 411 / S tot When the ratio is less than 0.20, the {411} oriented grains are not sufficiently developed, and therefore the magnetic properties are not adequately improved. Preferably, the area ratio S... 411 / S tot The value is 0.40 or higher, preferably 0.60 or higher. Area ratio S 411 / S tot The preferred value is higher, so there is no need to specify an upper limit; it can also be 1.00.

[0262] Similar to Embodiment 1, the relationship between the {411} oriented grains and the {411} oriented grains, which are considered to compete with the {411} oriented grains, is also important in strain-induced grain growth. Area ratio S 411 / S tra A larger area ratio ensures priority for {411} oriented grain growth and good magnetic properties. This area ratio S 411 / S tra A value less than 0.55 indicates that due to strain-induced grain growth, the {411} oriented grains are not sufficiently developed, and the oriented grains with a Taylor factor exceeding 2.8 are being eaten away by the oriented grains with smaller Taylor factors other than the {411} oriented grains. In this case, the in-plane anisotropy of the magnetic properties also increases. Therefore, in this embodiment, the area ratio S... 411 / S tra Set to 0.55 or higher. Preferably, the area ratio S 411 / S tra The area ratio S is 0.65 or higher, preferably 0.75 or higher. On the other hand, there is no need to specifically limit the area ratio S. 411 / S tra The upper limit is that orientation grains with a Taylor factor of 2.8 or less can also be {411} orientation grains.

[0263] Furthermore, in this embodiment, similar to Embodiment 1, the relationship with the {110} oriented grains is also specified. In this embodiment, the preferred area ratio S between the {411} oriented grains and the {110} oriented grains is... 411 / S 110 The following equation (18) is satisfied to ensure the priority of {411} oriented grain growth.

[0264] S 411 / S 110 ≥1.00···(18)

[0265] As shown in equation (18), in this embodiment, the preferred area ratio S is... 411 / S 110 The value is above 1.00. {110} oriented grains are well-developed in strain-induced grain growth, and this area is greater than S. 411 / S 110 When the value is less than 1.00, the anisotropy within the steel plate becomes very large, easily leading to undesirable properties. More preferably, the area ratio S... 411 / S 110 The value is 2.00 or higher, more preferably 4.00 or higher. Area ratio S 411 / S 110 The upper limit does not need to be specifically limited, and the area fraction of {110} oriented grains can also be zero. That is, even if the area ratio is S 411 / S 110 The infinitely divergent (18) equation also holds true.

[0266] Next, the requirements related to strain that should be satisfied in this embodiment will be explained. The strain of the non-oriented electromagnetic steel sheet in this embodiment is significantly reduced compared to the strain in the state after surface smooth rolling described in Embodiment 1, wherein the strain is characteristic of each crystal orientation.

[0267] The strain-related provisions in this embodiment differ in numerical range from those in equation (6) related to the aforementioned surface-rolled steel sheet, and satisfy the following equation (13).

[0268] K 411 / K tyl ≦1.010···(13)

[0269] If strain-induced grain growth proceeds sufficiently, the large portion of the strain in the steel plate is released, the strain of each crystal orientation becomes uniform, the strain variation is sufficiently small, and the ratio shown in equation (13) becomes close to 1.

[0270] Taking these variations into account, in order to obtain excellent magnetic properties in this embodiment, K is... 411 / K tyl Set it below 1.010. K 411 / K tyl Above 1.010, strain release is insufficient, resulting in insufficient reduction of iron loss, in particular. Preferably, K... 411 / K tyl The value is 0.990 or less, preferably 0.970 or less. Even if the non-oriented electromagnetic steel sheet of this embodiment is obtained by performing a first heat treatment on a steel sheet that satisfies the aforementioned equation (6), the value of equation (13) is considered to exceed 1.000 due to measurement errors, etc.

[0271] In the competition with the {411} oriented grains that should be preferentially grown, the relationship with oriented grains with a Taylor factor of 2.8 or less preferably satisfies equation (16).

[0272] K411 / K tra <1.010···(16)

[0273] To preferentially grow {411} oriented grains, K is preferably used. 411 / K tra Set it to be less than 1.010. This K 411 / K tra If the value is above 1.010, the strain release is insufficient, especially the reduction of iron loss is insufficient. A first heat treatment is performed on the non-oriented electromagnetic steel sheet that satisfies the above equation (7) to obtain a non-oriented electromagnetic steel sheet that satisfies equation (16).

[0274] In Embodiment 1, it was explained that the strain relationship with {110} oriented grains is preferred. On the other hand, in this embodiment, a condition is met where the large portion of the strain in the steel plate is released to ensure sufficient strain-induced grain growth. Therefore, K corresponds to the strain accumulated by the {110} oriented grains. 110 The value of strain is released to K 411 For values ​​of the same degree, similar to equation (9), it is preferable to satisfy equation (19).

[0275] K 411 / K 110 <1.010···(19)

[0276] That is, similar to equation (9), K is preferred. 411 / K 110 It is less than 1.010. This K 411 / K 110 When the value is above 1.010, there is insufficient strain release, especially insufficient reduction of iron loss. The non-oriented electromagnetic steel sheet that satisfies the above equation (9) is subjected to a first heat treatment to obtain a non-oriented electromagnetic steel sheet that satisfies equation (19).

[0277] In equations (13) and (19), in the absence of grains with an orientation equivalent to the distribution, no numerical evaluation is performed on the equation, and it is assumed that the equation is satisfied.

[0278] Next, the requirements related to the crystal grain size that should be satisfied in this embodiment will be explained. In a metallographic structure where strain-induced grain growth fully releases the large portion of strain, the crystal grain size of each crystal orientation has a significant impact on the magnetic properties. Grains in orientations that preferentially grow through strain-induced grain growth become coarse, while grains in orientations that are encroached upon by strain-induced grain growth become fine. In this embodiment, the relationship between the average crystal grain size satisfies equations (14) and (15).

[0279] d 411 / dave >1.00···(14)

[0280] d 411 / d tyl >1.00···(15)

[0281] These formulas represent the average grain size d of the preferentially growing orientation, i.e., the {411} oriented grains. 411 The ratio in equations (14) and (15) is preferably 1.30 or higher, more preferably 1.50 or higher, and even more preferably 2.00 or higher. There is no particular upper limit to these ratios, but although the grains of the grazing orientation grow slower than the {411} oriented grains, they also grow during the first heat treatment. Therefore, the above ratios are not likely to become excessively large, and the practical upper limit is about 10.00.

[0282] Furthermore, in this embodiment, it is preferable to satisfy equation (17).

[0283] d 411 / d tra >1.00···(17)

[0284] This formula represents the average grain size d of the preferentially growing orientation, i.e., the {411} oriented grains. 411 Relatively large. In formula (17), the ratio is preferably 1.30 or higher, more preferably 1.50 or higher, and particularly preferably 2.00 or higher. The upper limit of this ratio is not particularly limited, but although the grains of the grazing orientation grow slower than the {411} orientation grains, they still grow in the first heat treatment. Therefore, the above ratio is not likely to become excessively large, and the upper limit of practicality is about 10.00.

[0285] Furthermore, the range of average crystal grain size is not particularly limited, but if the average crystal grain size is too large, it is difficult to avoid the deterioration of magnetic properties. Therefore, in this embodiment, the average crystal grain size for practical use of relatively large grains, i.e., {411} oriented grains, is preferably set to 500 μm or less. More preferably, the average crystal grain size of {411} oriented grains is 400 μm or less, more preferably 300 μm or less, and particularly preferably 200 μm or less. On the other hand, if it is envisioned that a state of sufficient preferential growth of {411} orientation is ensured, then the lower limit of the average crystal grain size of {411} oriented grains is preferably 40 μm or more, more preferably 60 μm or more, and even more preferably 80 μm or more.

[0286] In equation (15), if there are no grains with an orientation equivalent to the denominator, no numerical evaluation is performed on this equation, and it is assumed that the equation is satisfied.

[0287] (Implementation Method 3)

[0288] In embodiments 1 and 2 described above, the strain of the steel sheet is determined by the KAM value and thus defined as a characteristic of the steel sheet. In this embodiment, the steel sheet described in embodiment 1 or 2 is annealed for a sufficiently long time to further promote grain growth. Such a steel sheet has strain-induced grain growth substantially completed, and as a result, the strain is also substantially completely released, making it a highly desirable characteristic. That is, a steel sheet that undergoes strain-induced grain growth to promote {411}-oriented grain growth, and then further undergoes normal grain growth in the second heat treatment until the strain is substantially completely released, becomes a steel sheet with stronger {411}-oriented aggregation. In this embodiment, the crystal orientation and grain size of the steel sheet obtained by performing a second heat treatment on the steel sheet described in embodiment 1 or 2 (i.e., a non-oriented electromagnetic steel sheet that has undergone a first heat treatment followed by a second heat treatment after surface rolling, or a non-oriented electromagnetic steel sheet that undergoes a second heat treatment without omitting the first heat treatment) will be described.

[0289] The crystal orientation of the steel sheet obtained by the second heat treatment satisfies the following equations (20) to (22). These specifications differ in numerical range from equations (3) to (5) related to the aforementioned non-oriented electromagnetic steel sheet after surface smooth rolling, and equations (10) to (12) related to the non-oriented electromagnetic steel sheet after strain-induced grain growth based on the first heat treatment. This is because, with strain-induced grain growth and the subsequent second heat treatment, the {411} oriented grains grow further, their area increases, and the oriented grains with a Taylor factor exceeding 2.8 are mainly consumed by the {411} oriented grains, further reducing their area.

[0290] S tyl / S tot <0.55···(20)

[0291] S 411 / S tot >0.30···(21)

[0292] S 411 / S tra ≧0.60···(22)

[0293] In this embodiment, the area ratio S is set. tyl / S tot Less than 0.55. Total area S tyl It can also be zero. The area ratio S tyl / S tot The upper limit is determined as one of the parameters representing the extent of {411} oriented grain growth. Area ratio S tyl / S totA value above 0.55 indicates that orientation grains with a Taylor factor exceeding 2.8, which should have been eliminated during the strain-induced grain growth stage, were not sufficiently eliminated. In this case, the magnetic properties cannot be adequately improved. Preferably, the area ratio S... tyl / S tot The value should be below 0.40, preferably below 0.30. Area ratio S tyl / S tot The smaller the value, the better; therefore, no lower limit is specified, and it can also be 0.00.

[0294] Furthermore, in this embodiment, the area ratio S 411 / S tot Set to exceed 0.30. Area ratio S 411 / S tot When the value is below 0.30, the magnetic properties are not sufficiently improved. Preferably, the area ratio S 411 / S tot The value should be 0.40 or higher, preferably 0.50 or higher. The so-called area ratio S... 411 / S tot The value of 1.00 refers to a situation where the crystal structure consists entirely of {411} oriented grains, with no other oriented grains present. However, this embodiment also considers this situation as an example.

[0295] Similar to embodiments 1 and 2, the relationship between the {411} oriented grains and the {411} oriented grains, which are considered to compete with the {411} oriented grains in strain-induced grain growth, is also important. In area ratio S 411 / S tra Under sufficiently large conditions, the priority of {411} oriented grain growth is ensured even in the normal grain growth condition following strain-induced grain growth, resulting in good magnetic properties. This area ratio S 411 / S tra When the value is less than 0.60, due to strain-induced grain growth, the {411} oriented grains are not sufficiently developed. In the normal grain growth state after strain-induced grain growth, the growth of oriented grains with small Taylor factors other than the {411} oriented grains is considerable, and the in-plane anisotropy of the magnetic properties also increases. Therefore, in this embodiment, the area ratio S... 411 / S tra Set to 0.60 or higher. Preferably, the area ratio S 411 / S tra The value is 0.70 or higher, preferably 0.80 or higher. On the other hand, the area ratio S... 411 / S tra The upper limit does not need to be specifically limited, and all orientation grains with a Taylor factor of 2.8 or less can be {411} orientation grains.

[0296] In the metallographic structure under conditions where strain-induced grain growth and subsequent normal grain growth are fully carried out, and the strain of the steel plate is almost completely released, the grain size of each crystal orientation has a significant impact on the magnetic properties. The {411} oriented grains that preferentially grow during strain-induced grain growth also become coarse grains after normal grain growth. In this embodiment, the relationship between the average grain size satisfies equations (23) and (24).

[0297] d 411 / d ave ≧0.95···(23)

[0298] d 411 / d tyl ≧0.95···(24)

[0299] These formulas represent the average grain size d of {411} oriented grains. 411 The ratios are at least 0.95 times the average grain size of the other grains. These ratios in equations (23) and (24) are preferably 1.00 or higher, more preferably 1.10 or higher, and even more preferably 1.20 or higher. There is no particular upper limit to these ratios, but during normal grain growth, grains other than {411}-oriented grains also grow. However, at the moment of normal grain growth, i.e., at the end of strain-induced grain growth, the {411}-oriented grains become coarse, exhibiting a so-called size advantage. The coarsening of {411}-oriented grains during normal grain growth is also advantageous, thus the above ratios maintain a sufficiently characteristic range. Therefore, a practical upper limit is approximately 10.00. If any of these ratios exceeds 10.00, it results in mixed grains, which may sometimes cause processing-related problems such as punching defects.

[0300] Furthermore, in the relationship of average crystal grain size, it is preferable to also satisfy the following equation (25).

[0301] d 411 / d tra ≧0.95···(25)

[0302] This formula represents the average grain size d of the preferentially growing orientation, i.e., the {411} oriented grains. 411The ratio in equation (25) is preferably 1.00 or higher, more preferably 1.10 or higher, and particularly preferably 1.20 or higher. While there is no particular upper limit to this ratio, during normal grain growth, grains other than {411}-oriented grains also grow. However, at the moment of normal grain growth, i.e., at the moment strain-induced grain growth is complete, the {411}-oriented grains become coarse, exhibiting a so-called size advantage. The coarsening of {411}-oriented grains during normal grain growth is also advantageous, thus the above ratio maintains a sufficiently characteristic range. Therefore, the upper limit for practicality is approximately 10.00. When any of these ratios exceeds 10.0, it becomes mixed grains, potentially causing processing-related problems such as punching defects.

[0303] Furthermore, the range of average crystal grain size is not particularly limited, but if the average crystal grain size is too large, it is difficult to avoid the deterioration of magnetic properties. Therefore, similar to Embodiment 2, in this embodiment, the average crystal grain size for practical use of relatively large grains, i.e., {411} oriented grains, is preferably 500 μm or less. More preferably, the average crystal grain size of the {411} oriented grains is 400 μm or less, more preferably 300 μm or less, and particularly preferably 200 μm or less. On the other hand, the lower limit of the average crystal grain size of the {411} oriented grains, if considering the condition of ensuring sufficient preferential growth of {411} orientation, is preferably 40 μm or more, more preferably 60 μm or more, and more preferably 80 μm or more.

[0304] In equation (24), if there are no grains with an orientation equivalent to the denominator, no numerical evaluation is performed on this equation, and it is assumed that the equation is satisfied.

[0305] [characteristic]

[0306] The non-oriented electromagnetic steel sheet of this embodiment controls the chemical composition and metallographic structure as described above, thus obtaining excellent magnetic properties (low iron loss) not only in the rolling direction and width direction average, but also in the whole circumference average (rolling direction, width direction, direction at 45 degrees relative to the rolling direction, and direction at 135 degrees relative to the rolling direction average).

[0307] The rolling direction and width direction mentioned here refer to the rolling direction and width direction of the obtained non-oriented electromagnetic steel sheet.

[0308] Magnetic measurements can be performed using the methods described in JIS C 2550-1 (2011) and JIS C 2550-3 (2019), or using the method described in JIS C 2556 (2015). Furthermore, if the sample is too small to be measured using the methods described in the JIS standards, the electromagnetic circuit can be measured using an apparatus based on JIS C 2556 (2015) capable of measuring test pieces of 55 mm square or smaller.

[0309] Next, the manufacturing method of the non-oriented electromagnetic steel sheet according to this embodiment will be described. In this embodiment, an oriented electromagnetic steel sheet is used as the material, and a cold rolling process in the width direction, an intermediate annealing process, and a surface smoothing process are performed.

[0310] First, as the material for cold rolling, an orientation-oriented electromagnetic steel sheet having the aforementioned chemical composition is used. If the orientation-oriented electromagnetic steel sheet has the aforementioned chemical composition, a steel sheet manufactured by a known method can be used. That is, an orientation-oriented electromagnetic steel sheet manufactured by a known method (for example, an orientation-oriented electromagnetic steel sheet satisfying JIS C 2553 (2019) or a specification product of each steel company). The orientation-oriented electromagnetic steel sheet is manufactured through a billet heating process, a hot rolling process, a cold rolling process, a decarburization annealing process, a nitriding treatment, and a final annealing process. The thickness of the cold-rolled orientation-oriented electromagnetic steel sheet in the width direction is preferably set to 0.27 to 0.35 mm. Alternatively, instead of an orientation-oriented electromagnetic steel sheet, a material from which Gaussian-oriented grains are cut in a plate shape from a single crystal generated using a material having the aforementioned chemical composition can also be used.

[0311] For oriented electromagnetic steel sheets as described above, in the cold rolling process, the sheet is cold rolled at a rolling rate (cumulative rolling rate) of 20% to 50% in the width direction (cold rolling process). When the rolling rate in the width direction is less than 20%, almost no crystal rotation occurs, and the orientation that forms nuclei for {411} recrystallized grains cannot be formed. Furthermore, if the rolling rate is higher than 50%, the skewness of the steel sheet becomes too large, and the nuclei for {411} recrystallized grains degenerate into nuclei for {111} recrystallized grains. Preferably, the rolling rate in the width direction during cold rolling is 30% to 40%.

[0312] Oriented electromagnetic steel sheets are mainly composed of {110}<001> oriented grains, with the width direction being {110}<110> oriented. If the {110}<110> oriented grains are rolled and recrystallized, a {411} orientation may sometimes be found. This mechanism is utilized in this embodiment.

[0313] The width direction of the so-called oriented electromagnetic steel sheet is determined by the rolling mark at a 90-degree angle. When cutting from a single crystal, the same rolling process as described above is performed in a direction parallel to the <110> direction, followed by recrystallization.

[0314] After cold rolling, intermediate annealing (intermediate annealing process) is performed. In this embodiment, intermediate annealing is performed at a temperature of 650°C or higher, for example. If the intermediate annealing temperature is lower than 650°C, recrystallization will not occur, the {411} oriented grains cannot grow sufficiently, the magnetic flux density cannot increase, and sometimes the effect of improving iron loss cannot be fully obtained. Therefore, the intermediate annealing temperature is set to 650°C or higher. There is no upper limit to the intermediate annealing temperature, but when the intermediate annealing temperature is higher than 900°C, the grains become too large, making it difficult to grow during subsequent surface finishing, strain-induced grain growth, and also making it difficult for {411} oriented grains to grow. Therefore, the intermediate annealing temperature is preferably set to 650–900°C.

[0315] Furthermore, the annealing time (holding time) is preferably set to 1 to 60 seconds. When the annealing time is less than 1 second, the time available for recrystallization becomes too short, and there is a possibility that the {411} oriented grains may not grow sufficiently. In addition, if the annealing time exceeds 60 seconds, it will unnecessarily increase the cost, and therefore is not desirable.

[0316] After intermediate annealing, surface finishing rolling (surface finishing process) is performed. As mentioned above, rolling is performed when there are many {411} oriented grains, which further promotes the growth of the {411} oriented grains. Surface finishing rolling is performed in the same direction as the aforementioned cold rolling (the width direction of the oriented electromagnetic steel sheet), and the rolling rate of surface finishing rolling is preferably set to 5% to 30%. When the rolling rate is less than 5%, the unevenness in sheet thickness caused by cold rolling in the width direction cannot be eliminated. Furthermore, if the rolling rate is higher than 30%, the {411} oriented grains will not grow because of the growth of {111} oriented grains with poor magnetic properties.

[0317] Next, a first heat treatment (first heat treatment step) is performed to promote strain-induced grain growth. The first heat treatment is preferably performed at 700 to 950°C for 1 to 100 seconds.

[0318] When the heat treatment temperature is below 700°C, strain-induced grain growth will not occur. Furthermore, at temperatures above 950°C, not only will strain-induced grain growth occur, but normal grain growth will also occur, and the metallographic structure described in Embodiment 2 above cannot be obtained.

[0319] Furthermore, production efficiency decreases significantly when the heat treatment time (holding time) exceeds 100 seconds, making it impractical. Setting the holding time to less than 1 second is not easy in industrial applications, so the holding time is set to more than 1 second.

[0320] The first heat treatment step can also be omitted. That is, the first heat treatment can be omitted after the surface rolling process, and the second heat treatment described later can be performed instead.

[0321] After the surface rolling process or the first heat treatment process, the non-oriented electromagnetic steel sheet is subjected to a second heat treatment (second heat treatment process). Preferably, the second heat treatment process is carried out for 1 to 100 seconds at a temperature range of 950 to 1050°C, or for more than 1000 seconds at a temperature range of 700 to 900°C.

[0322] By performing heat treatment within the aforementioned temperature range and time, if the first heat treatment is omitted, normal grain growth occurs after strain-induced grain growth; if the first heat treatment is performed, normal grain growth occurs. Furthermore, sometimes strain-induced grain growth is performed in a subsequent second heat treatment, depending on the conditions of the first heat treatment.

[0323] The non-oriented electromagnetic steel sheet of this embodiment can be manufactured as described above. However, this manufacturing method is only an example of a method for manufacturing the non-oriented electromagnetic steel sheet of this embodiment, and is not limited to a single manufacturing method.

[0324] Example

[0325] Next, embodiments of the non-oriented electromagnetic steel sheet of the present invention will be shown and described in detail. The embodiments shown below are merely examples of the non-oriented electromagnetic steel sheet of the present invention, and the non-oriented electromagnetic steel sheet of the present invention is not limited to the following examples.

[0326] (First Embodiment)

[0327] Materials (base materials) with the chemical compositions shown in Tables 1A and 1C were prepared and used as test specimens. (Nos. 116 and 151 are non-oriented electromagnetic steel sheets. Nos. 117 to 150 are materials with Gaussian oriented grains cut from single crystals in a plate shape. The others are oriented electromagnetic steel sheets). Here, the left side of equation (1) refers to the value of the left side of the aforementioned equation (1). Subsequently, the material was cold-rolled in the width direction (in the case of cutting from single crystals, in the direction parallel to the <110> direction) to obtain a cold-rolled sheet. After removing the insulating coating, the oriented electromagnetic steel sheet was cold-rolled in the width direction. The rolling rate of the cold rolling at this time is shown in Tables 1B and 1D.

[0328] The cold-rolled sheet was subjected to intermediate annealing for 30 seconds at the temperatures shown in Tables 1B and 1D in a non-oxidizing atmosphere, followed by a second cold rolling (surface finishing) at the rolling rates shown in Tables 1B and 1D. This surface finishing was performed in the same direction as the aforementioned cold rolling.

[0329] Next, to investigate the texture, a portion of the steel plate was cut off, and the cut test piece was processed to half its original thickness. EBSD observations were then performed on the processed surface (parallel to the steel plate surface) using the aforementioned method (step interval: 100 nm). The area and average KAM value of the oriented grains for the types shown in Tables 2A and 2B were determined through EBSD observations.

[0330] Furthermore, as a second heat treatment, the steel sheet was annealed at 800°C for 2 hours. From the steel sheet after the second heat treatment, 55mm square specimens were taken as test samples. At this time, specimens were collected with one side parallel to the rolling direction and specimens inclined at 45 degrees relative to the rolling direction. Furthermore, the specimens were taken using a shearing machine. Then, the iron loss W10 / 400 (average value of energy loss in the rolling direction and width direction when the test piece is energized at a maximum magnetic flux density of 1.0T and a frequency of 400Hz) and W10 / 400 (full circle) (average value of energy loss in the rolling direction, width direction, 45 degrees relative to the rolling direction, and 135 degrees relative to the rolling direction when the test piece is energized at a maximum magnetic flux density of 1.0T and a frequency of 400Hz) were measured according to JISC 2556 (2015) standards. The measurement results are shown in Tables 2A and 2B.

[0331] [Table 1A]

[0332]

[0333] [Table 1B]

[0334]

[0335] [Table 1C]

[0336]

[0337] [Table 1D]

[0338]

[0339] [Table 2A]

[0340]

[0341] [Table 2B]

[0342]

[0343] The underlines in Tables 1A to 1D and Tables 2A and 2B indicate conditions that deviate from the scope of this invention. Examples of the invention, Nos. 101 to 110, 117 to 138, and 148 to 150, all represent good values ​​for iron loss W10 / 400 and W10 / 400 (full cycle).

[0344] On the other hand, No.111 to No.116, as comparative examples, do not satisfy equation (1), or at least one of the following is not suitable: the temperature during intermediate annealing, the rolling rate during cold rolling, or the rolling rate during surface finishing. Therefore, at least one of equations (3) to (6) is not satisfied, resulting in high iron loss W10 / 400 and W10 / 400 (whole circumference).

[0345] Furthermore, in comparative examples No.139 to No.147, the chemical composition deviates from the scope of the present invention, resulting in breakage during cold rolling, or failing to satisfy equations (3) to (4), resulting in high iron loss W10 / 400 and W10 / 400 (whole circumference).

[0346] Furthermore, in comparison No.151, non-oriented electromagnetic steel sheet was used as the material (base material). Therefore, although the chemical composition or temperature during intermediate annealing, the rolling rate during cold rolling, and the rolling rate during surface smooth rolling were satisfied, Equations (3) to (4) were not satisfied. As a result, the iron loss W10 / 400 and W10 / 400 (whole circle) were high.

[0347] (Second Embodiment)

[0348] Materials with the chemical compositions shown in Tables 3A and 3C were produced (only No. 217 is a non-oriented electromagnetic steel sheet, and Nos. 224 to 248 are materials with Gaussian oriented grains cut from single crystals in a plate shape. The others are oriented electromagnetic steel sheets). Here, the left side of equation (1) refers to the value of the left side of the aforementioned equation (1). Subsequently, cold rolling was performed in the width direction of the material (the direction parallel to the <110> direction when cut from the single crystal) to obtain a cold-rolled sheet. After removing the insulating coating, the oriented electromagnetic steel sheet was cold-rolled in the width direction. The rolling ratio of the cold rolling at this time is shown in Tables 3B and 3D.

[0349] The cold-rolled sheet was subjected to intermediate annealing for 30 seconds at the temperatures shown in Tables 3B and 3D in a non-oxidizing atmosphere, followed by a second cold rolling (surface finishing) at the rolling rates shown in Tables 3B and 3D. This surface finishing was performed in the same direction as the aforementioned cold rolling.

[0350] To investigate the texture after surface light rolling, a portion of the steel sheet was cut and its thickness reduced to half. EBSD observation (step interval: 100 nm) was then performed on this processed surface using the aforementioned method. Through EBSD observation, the area and average KAM value of each orientation grain were determined, and the S... tyl / S tot S 411 / S tot S 411 / S tra K 411 / K tyl The results are shown in Tables 3B and 3D.

[0351] Next, a first heat treatment was performed under the conditions shown in Tables 3B and 3D. After the first heat treatment, in order to investigate the texture, a portion of the steel plate was cut off, and the cut test piece was processed to half its original thickness. EBSD observation was performed on this processed surface using the methods described above. Through EBSD observation, the area, average KAM value, and average crystal grain size of the types shown in Tables 4A and 4B were determined.

[0352] Furthermore, the steel sheet was annealed at 800°C for 2 hours as a second heat treatment. A 55mm square sample was taken from the steel sheet after the second heat treatment as the test specimen. At this time, samples with one side parallel to the rolling direction and samples inclined at 45 degrees relative to the rolling direction were taken. Furthermore, the samples were taken using a shearing machine. Then, similarly to the first embodiment, the iron loss W10 / 400 (average value in the rolling direction and width direction) and W10 / 400 (full circumference) of the magnetic properties were measured (average value in the rolling direction, width direction, direction at 45 degrees relative to the rolling direction, and direction at 135 degrees relative to the rolling direction). The measurement results are shown in Tables 4A and 4B.

[0353] [Table 3A]

[0354]

[0355] [Table 3B]

[0356]

[0357] [Table 3C]

[0358]

[0359] [Table 3D]

[0360]

[0361] [Table 4A]

[0362]

[0363] [Table 4B]

[0364]

[0365] The underlined values ​​in Tables 3A to 3D and Tables 4A and 4B indicate conditions that are outside the scope of this invention. Examples of the invention, Nos. 201 to 210 and Nos. 218 to 239, all have good values ​​for iron loss W10 / 400 and W10 / 400 (full cycle).

[0366] On the other hand, as comparative examples No.211 to No.217 do not satisfy equation (1), or at least one of the following is not suitable: the temperature in intermediate annealing, the rolling rate in cold rolling, the rolling rate in surface finishing rolling, or the temperature in the first heat treatment. As a result, they do not satisfy any of equations (10) to (15), and iron loss W10 / 400 and W10 / 400 (whole circumference) are high.

[0367] Furthermore, as comparative examples No.240 to No.248, due to their chemical composition deviating from the scope of the present invention, fractured during cold rolling or did not satisfy formulas (10) to (11), resulting in high iron loss W10 / 400 and W10 / 400 (whole circumference).

[0368] (Third Embodiment)

[0369] Materials with the chemical compositions shown in Tables 5A and 5C are produced (only No. 316 is a non-oriented electromagnetic steel sheet, and Nos. 317 to 342 are materials with Gaussian oriented grains cut from single crystals in a plate-like shape. The others are oriented electromagnetic steel sheets). Here, the left side of equation (1) refers to the value of the left side of the aforementioned equation (1). Subsequently, the material is cold-rolled in the width direction (in the case of cutting from single crystals, the direction parallel to the <110> direction) to obtain a cold-rolled sheet. After removing the insulating coating, the oriented electromagnetic steel sheet is cold-rolled in the width direction. The rolling ratio of the cold rolling at this time is shown in Tables 5B and 5D.

[0370] The cold-rolled sheet was subjected to intermediate annealing for 30 seconds at the temperatures shown in Tables 5B and 5D in a non-oxidizing atmosphere, followed by a second cold rolling (surface finishing) at the rolling rates shown in Tables 5B and 5D. This surface finishing was performed in the same direction as the aforementioned cold rolling.

[0371] To investigate the texture after surface light rolling, a portion of the steel sheet was cut and its thickness reduced to half. EBSD observation (step interval: 100 nm) was then performed on this processed surface using the aforementioned method. Through EBSD observation, the area and average KAM value of each orientation grain were determined, and the S... tyl / S tot S411 / S tot S 411 / S tra K 411 / K tyl The results are shown in Tables 5B and 5D.

[0372] Next, without the first heat treatment, a second heat treatment was performed under the conditions shown in Tables 5B and 5D. After the second heat treatment, in order to investigate the texture, a portion of the steel plate was cut off, and the cut test piece was machined to half its original thickness. EBSD observation was performed on this machined surface. Through EBSD observation, the area and average crystal grain size of the types shown in Table 6 were obtained.

[0373] Furthermore, after the second heat treatment described above, a 55 mm square sample sheet was taken from the steel plate after the second heat treatment as the test specimen. At this time, a sample sheet with one side parallel to the rolling direction and a sample sheet inclined at 45 degrees relative to the rolling direction were used. Furthermore, the sample taking was performed using a shearing machine. Then, similarly to the first embodiment, the iron loss W10 / 400 (average value in the rolling direction and width direction) and W10 / 400 (full circumference) of the magnetic properties were measured (average value in the rolling direction, width direction, direction at 45 degrees relative to the rolling direction, and direction at 135 degrees relative to the rolling direction). The measurement results are shown in Table 6.

[0374] [Table 5A]

[0375]

[0376] [Table 5B]

[0377]

[0378] [Table 5C]

[0379]

[0380] [Table 5D]

[0381]

[0382] [Table 6]

[0383]

[0384] The underlined values ​​in Tables 5A to 5D and Table 6 indicate conditions that are outside the scope of this invention. Examples of the invention No. 301 to No. 310, No. 317 to No. 332, and No. 342 all have good values ​​for iron loss W10 / 400 and W10 / 400 (full cycle).

[0385] On the other hand, as comparative examples No.311 to No.316, since they do not satisfy equation (1), or at least one of the following is not suitable: the temperature in intermediate annealing, the rolling rate in cold rolling, or the rolling rate in surface finishing rolling, they do not satisfy at least one of equations (20) to (24), resulting in high iron loss W10 / 400 and W10 / 400 (whole circumference).

[0386] Furthermore, as comparative examples No.333 to No.341, due to their chemical composition deviating from the scope of the present invention, fractured during cold rolling or did not satisfy equations (20) to (21), resulting in high iron loss W10 / 400 and W10 / 400 (whole circumference).

[0387] (Fourth Embodiment)

[0388] Materials with the chemical compositions shown in Tables 7A and 7C are produced (only No. 416 is a non-oriented electromagnetic steel sheet, and Nos. 423 to 248 are materials with Gaussian oriented grains cut from single crystals in a plate-like shape. The others are oriented electromagnetic steel sheets). Here, the left side of equation (1) refers to the value of the left side of the aforementioned equation (1). Subsequently, the material is cold-rolled in the width direction (in the case of cutting from single crystals, in the direction parallel to the <110> direction) to obtain a cold-rolled sheet. After removing the insulating coating, the oriented electromagnetic steel sheet is cold-rolled in the width direction. The rolling rate of the cold rolling at this time is shown in Tables 7B and 7D.

[0389] The cold-rolled sheet was subjected to intermediate annealing for 30 seconds at the temperatures shown in Tables 7B and 7D in a non-oxidizing atmosphere, followed by a second cold rolling (surface finishing) at the rolling rates shown in Tables 7B and 7D. This surface finishing was performed in the same direction as the aforementioned cold rolling.

[0390] Next, the first heat treatment was carried out at 800°C for 30 seconds.

[0391] After the first heat treatment, to investigate the texture, a portion of the steel plate was cut off, and the cut test piece was processed to half its original thickness. EBSD observation (step interval: 100 nm) was performed on this processed surface using the aforementioned method. Through EBSD observation, the area, average KAM value, and average grain size of various orientation grains were determined, and S was calculated. tyl / S tot S 411 / S tot S 411 / S tra K 411 / K tyl d 411 / d ave d 411 / d tyl .

[0392] The steel sheet after the first heat treatment was subjected to a second heat treatment under the conditions shown in Tables 7B and 7D. After the second heat treatment, a portion of the steel sheet was cut off to investigate the texture. The cut test piece was then machined to half its original thickness, and EBSD observation was performed on the machined surface. The area and average grain size of the types shown in Table 8 were obtained through EBSD observation.

[0393] Furthermore, using the steel plate after the second heat treatment described above as the test specimen, a 55mm square specimen was taken. At this time, specimens with one side parallel to the rolling direction and specimens inclined at 45 degrees relative to the rolling direction were taken. Furthermore, the specimens were taken using a shearing machine. Also, similarly to the first embodiment, the magnetic properties of iron loss W10 / 400 (average value in the rolling direction and width direction) and W10 / 400 (full circumference) were measured (average value in the rolling direction, width direction, direction at 45 degrees relative to the rolling direction, and direction at 135 degrees relative to the rolling direction). The measurement results are shown in Table 8.

[0394] [Table 7A]

[0395]

[0396] [Table 7B]

[0397]

[0398] [Table 7C]

[0399]

[0400] [Table 7D]

[0401]

[0402] [Table 8]

[0403]

[0404] The underlined values ​​in Tables 7A-7D and Table 8 indicate conditions that are outside the scope of this invention. Examples of the invention, Nos. 401-410, 417, 419, 420, 423-438, and 448, all represent good values ​​for iron loss W10 / 400 and W10 / 400 (whole cycle).

[0405] On the other hand, for the comparative examples No.411 to No.416, at least one of the following is not suitable: (1) the temperature in intermediate annealing, the rolling rate in cold rolling, and the rolling rate in surface finishing rolling. As a result, at least one of the following does not satisfy: (20) to (24) the iron loss W10 / 400 and W10 / 400 (whole circle) are high.

[0406] Furthermore, as comparative examples No.418, No.421, and No.422 do not satisfy at least one of equations (20) to (24) because the temperature or time of the second heat treatment is not suitable. As a result, the iron loss W10 / 400 and W10 / 400 (whole cycle) are high.

[0407] Furthermore, as comparative examples No.439 to No.447, due to their chemical composition deviating from the scope of the present invention, fractured during cold rolling or did not satisfy equations (20) to (21), resulting in high iron loss W10 / 400 and W10 / 400 (whole circumference).

[0408] (Fifth Embodiment)

[0409] Oriented electromagnetic steel sheets with the chemical composition shown in Table 9A are produced. Here, the left-hand side of equation (1) refers to the value of the left-hand side of the aforementioned equation (1). Subsequently, the insulating coating of the produced oriented electromagnetic steel sheet is removed, and it is cold-rolled in the width direction. The rolling ratio of the cold rolling at this time is shown in Table 9B.

[0410] The cold-rolled sheet was subjected to intermediate annealing for 30 seconds at the temperature shown in Table 9B in a non-oxidizing atmosphere, followed by a second cold rolling (surface finishing) at the rolling rate shown in Table 9B. This surface finishing was performed in the same direction as the aforementioned cold rolling.

[0411] Next, to investigate the texture, a portion of the steel plate was cut off, and the cut test piece was processed to half its original thickness. EBSD observations were then performed on this processed surface (step interval: 100 nm). The area and average KAM value of the types shown in Table 10 were obtained through EBSD observations.

[0412] Furthermore, as a second heat treatment, the steel sheet was annealed at 800°C for 2 hours. From the steel sheet after the second heat treatment, 55mm square specimens were taken as test samples. At this time, specimens with one side parallel to the rolling direction and specimens inclined at 45 degrees relative to the rolling direction were taken. Furthermore, the specimens were taken using a shearing machine. Then, similarly to the first embodiment, the iron loss W10 / 400 (average value in the rolling direction and width direction) and W10 / 400 (full circumference) of the magnetic properties were measured (average value in the rolling direction, width direction, direction at 45 degrees relative to the rolling direction, and direction at 135 degrees relative to the rolling direction). The measurement results are shown in Table 10.

[0413] [Table 9A]

[0414]

[0415] [Table 9B]

[0416]

[0417] [Table 10]

[0418]

[0419] Examples of the invention No. 501 to No. 518 all satisfy equations (3) to (9), and all have good values ​​for iron loss W10 / 400 and W10 / 400 (full cycle).

[0420] Industrial availability

[0421] According to the present invention, a non-oriented electromagnetic steel sheet with excellent magnetic properties over an integer average period and a method for manufacturing the same are provided. Therefore, the present invention has high industrial applicability.

Claims

1. A non-oriented electromagnetic steel sheet, characterized in that, It contains the following chemical components: By mass%, it contains C: Below 0.0100% Si: 1.50%–4.00% One or more of the elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: the total percentage is less than 2.50%. sol.Al: 4.000% or less, S: Below 0.0400% N: below 0.0100% Sn: 0.00%~0.40% Sb: 0.00%~0.40% P：0.00％～0.40％、 Cr：0.000％～0.100％、 B：0.0000％～0.0050％、 O: 0.0000%~0.0200%, and One or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%. When the mass percentage of Mn content is set to [Mn], the mass percentage of Ni content is set to [Ni], the mass percentage of Co content is set to [Co], the mass percentage of Pt content is set to [Pt], the mass percentage of Pb content is set to [Pb], the mass percentage of Cu content is set to [Cu], the mass percentage of Au content is set to [Au], the mass percentage of Si content is set to [Si], and the mass percentage of sol.Al content is set to [sol.Al], the following equation (1) is satisfied. ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%···(1) The remaining part consists of Fe and impurities. Furthermore, when observing through EBSD with a surface parallel to the steel plate surface, the total area is set as S. tot Let the area of ​​the {411} oriented grains be S. 411 Let S be the area of ​​the orientation grains whose Taylor factor M exceeds 2.8 based on the following equation (2). tyl Let S be the total area of ​​the oriented grains with a Taylor factor M of 2.8 or less. tra The average KAM value of the {411} oriented grains is set as K. 411 The average KAM value of the orientation grains with a Taylor factor M exceeding 2.8 is set as K. tyl When, the following equations (3) to (6) are satisfied, 0.20≦S tyl / S tot ≦0.85···(3) 0.05≦S 411 / S tot ≦0.80···(4) S 411 / S tra ≧0.50···(5) K 411 / K tyl ≦0.990···(6) Here, in equation (2) λ represents the angle between the stress vector and the sliding direction vector of the crystal, and λ represents the angle between the stress vector and the normal vector of the sliding surface of the crystal.

2. The non-oriented electromagnetic steel sheet according to claim 1, characterized in that, Furthermore, the average KAM value of the oriented grains with a Taylor factor M of 2.8 or less is set as K. tra When, the following equation (7) is satisfied, K 411 / K tra <1.010···(7)。 3. The non-oriented electromagnetic steel sheet according to claim 1, characterized in that, Furthermore, when the area of ​​the {110} oriented grains is set to S... 110 When, the following equation (8) is satisfied, S 411 / S 110 ≧1.00···(8) Here, equation (8) is set to be even if the area ratio S 411 / S 110 The statement that it can be extended to infinity also holds true.

4. The non-oriented electromagnetic steel sheet according to claim 1, characterized in that, Furthermore, when the average KAM value of the {110} oriented grains is set to K... 110 When, the following equation (9) is satisfied. K 411 / K 110 <1.010···(9)。 5. A non-oriented electromagnetic steel sheet, characterized in that, It has the following chemical components: By mass%, it contains C: Below 0.0100% Si: 1.50%–4.00% One or more of the elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: the total percentage is less than 2.50%. sol.Al: 4.000% or less, S: Below 0.0400% N: below 0.0100% Sn: 0.00%~0.40% Sb: 0.00%~0.40% P：0.00％～0.40％、 Cr：0.000％～0.100％、 B：0.0000％～0.0050％、 O: 0.0000%~0.0200%, and One or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%. When the mass percentage of Mn content is set to [Mn], the mass percentage of Ni content is set to [Ni], the mass percentage of Co content is set to [Co], the mass percentage of Pt content is set to [Pt], the mass percentage of Pb content is set to [Pb], the mass percentage of Cu content is set to [Cu], the mass percentage of Au content is set to [Au], the mass percentage of Si content is set to [Si], and the mass percentage of sol.Al content is set to [sol.Al], the following equation (1) is satisfied. ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%···(1) The remaining part consists of Fe and impurities. Furthermore, when observing through EBSD with a surface parallel to the steel plate surface, the total area is set as S. tot Let the area of ​​the {411} oriented grains be S. 411 Let S be the area of ​​the orientation grains whose Taylor factor M exceeds 2.8 based on the following equation (2). tyl Let S be the total area of ​​the oriented grains with a Taylor factor M of 2.8 or less. tra The average KAM value of the {411} oriented grains is set as K. 411 The average KAM value of the orientation grains with a Taylor factor M exceeding 2.8 is set as K. tyl Set the average crystal grain size of the observation area as d. ave The average grain size of the {411} oriented grains is set as d. 411 The average grain size of the orientation grains with a Taylor factor M exceeding 2.8 is set as d. tyl When the following equations (10) to (15) are satisfied, S tyl / S tot ≦0.70···(10) 0.20≦S 411 / S tot ···(11) S 411 / S tra ≧0.55···(12) K 411 / K tyl ≦1.010···(13) d 411 / d ave >1.00···(14) d 411 / d tyl >1.00···(15) Here, in equation (2) λ represents the angle between the stress vector and the sliding direction vector of the crystal, and λ represents the angle between the stress vector and the normal vector of the sliding surface of the crystal.

6. The non-oriented electromagnetic steel sheet according to claim 5, characterized in that, Furthermore, the average KAM value of the oriented grains with a Taylor factor M of 2.8 or less is set as K. tra When, the following equation (16) is satisfied. K 411 / K tra <1.010···(16)。 7. The non-oriented electromagnetic steel sheet according to claim 5, characterized in that, Furthermore, the average grain size of the oriented grains with a Taylor factor M of 2.8 or less is set as d. tra Under the condition that the following equation (17) is satisfied. d 411 / d tra >1.00···(17)。 8. The non-oriented electromagnetic steel sheet according to claim 5, characterized in that, Furthermore, the area of ​​the {110} oriented grains is set as S. 110 When, the following equation (18) is satisfied, S 411 / S 110 ≧1.00···(18) Here, equation (18) is set to be even if the area ratio S 411 / S 110 The statement that it can be extended to infinity also holds true.

9. The non-oriented electromagnetic steel sheet according to claim 5, characterized in that, Furthermore, the average KAM value of the {110} oriented grains is set as K 110 When, the following equation (19) is satisfied, K 411 / K 110 <1.010···(19)。 10. The non-oriented electromagnetic steel sheet according to any one of claims 1 to 9, characterized in that, The chemical components, by mass%, contain from [the following components]: Sn: 0.02%–0.40% Sb: 0.02%–0.40%, and P: Select one or more groups consisting of 0.02% to 0.40%.

11. The non-oriented electromagnetic steel sheet according to any one of claims 1 to 9, characterized in that, The chemical component, by mass%, contains one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd, totaling 0.0005% to 0.0100%.

12. A method for manufacturing a non-oriented electromagnetic steel sheet, comprising the method for manufacturing a non-oriented electromagnetic steel sheet according to any one of claims 1 to 4, characterized in that, have: For oriented electromagnetic steel sheets, a cold rolling process is performed in the width direction at a rolling rate of 20% to 50%. The cold-rolled steel sheet is then subjected to an intermediate annealing process at a temperature of 650°C or higher; and For the steel sheet that has undergone the intermediate annealing, a surface finishing rolling process is performed in the same direction as the cold rolling direction at a rolling rate of 5% to 30%. The oriented electromagnetic steel sheet has the following chemical composition: By mass%, it contains C: Below 0.0100% Si: 1.50%–4.00% One or more of the elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: the total percentage is less than 2.50%. sol.Al: 4.000% or less, S: Below 0.0400% N: below 0.0100% Sn: 0.00%~0.40% Sb: 0.00%~0.40% P：0.00％～0.40％、 Cr：0.000％～0.100％、 B：0.0000％～0.0050％、 O: 0.0000%~0.0200%, and One or more of the elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%. When the mass percentage of Mn content is set to [Mn], the mass percentage of Ni content is set to [Ni], the mass percentage of Co content is set to [Co], the mass percentage of Pt content is set to [Pt], the mass percentage of Pb content is set to [Pb], the mass percentage of Cu content is set to [Cu], the mass percentage of Au content is set to [Au], the mass percentage of Si content is set to [Si], and the mass percentage of sol.Al content is set to [sol.Al], the following equation (1) is satisfied. ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%···(1), The remainder consists of Fe and impurities.

13. A method for manufacturing a non-oriented electromagnetic steel sheet, comprising the method for manufacturing a non-oriented electromagnetic steel sheet according to any one of claims 5 to 9, characterized in that, The non-oriented electromagnetic steel sheet according to any one of claims 1 to 4 is subjected to heat treatment at a temperature of 700°C to 950°C for 1 to 100 seconds.

14. A non-oriented electromagnetic steel sheet, characterized in that, It has the following chemical components: By mass%, it contains C: Below 0.0100% Si: 1.50%–4.00% One or more of the elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu, and Au: the total percentage is less than 2.50%. sol.Al: 4.000% or less, S: Below 0.0400% N: below 0.0100% Sn: 0.00%~0.40% Sb: 0.00%~0.40% P：0.00％～0.40％、 Cr：0.000％～0.100％、 B：0.0000％～0.0050％、 O: 0.0000%~0.0200%, and One or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: totaling 0.0000% to 0.0100%. When the mass percentage of Mn content is set to [Mn], the mass percentage of Ni content is set to [Ni], the mass percentage of Co content is set to [Co], the mass percentage of Pt content is set to [Pt], the mass percentage of Pb content is set to [Pb], the mass percentage of Cu content is set to [Cu], the mass percentage of Au content is set to [Au], the mass percentage of Si content is set to [Si], and the mass percentage of sol.Al content is set to [sol.Al], the following equation (1) is satisfied. ([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])-([Si]+[sol.Al])≦0.00%···(1) The remaining part consists of Fe and impurities. Furthermore, when observing through EBSD with a surface parallel to the steel plate surface, the total area is set as S. tot Let the area of ​​the {411} oriented grains be S. 411 Let S be the area of ​​the orientation grains whose Taylor factor M exceeds 2.8 based on the following equation (2). tyl Let S be the total area of ​​the oriented grains with a Taylor factor M of 2.8 or less. tra Set the average crystal grain size of the observation area as d. ave The average grain size of the {411} oriented grains is set as d. 411 The average grain size of the orientation grains with a Taylor factor M exceeding 2.8 is set as d. tyl When, the following equations (20) to (24) are satisfied, S tyl / S tot <0.55···(20) S 411 / S tot >0.30···(21)S 411 / S tra ≧0.60···(22) d 411 / d ave ≧0.95···(23) d 411 / d tyl ≧0.95···(24) Here, in equation (2) λ represents the angle between the stress vector and the sliding direction vector of the crystal, and λ represents the angle between the stress vector and the normal vector of the sliding surface of the crystal.

15. The non-oriented electromagnetic steel sheet according to claim 14, characterized in that, Furthermore, the average grain size of the oriented grains with a Taylor factor M of 2.8 or less is set as d. tra When, the following equation (25) is satisfied, d 411 / d tra ≧0.95···(25)。 16. A method for manufacturing a non-oriented electromagnetic steel sheet, characterized in that, The non-oriented electromagnetic steel sheet according to any one of claims 1 to 11 is subjected to heat treatment at a temperature of 950°C to 1050°C for 1 to 100 seconds, or at a temperature of 700°C to 900°C for more than 1000 seconds.

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