RU2779984C1 - Sheet of anisotropic electrotechnical steel and method for manufacture thereof - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely, to the manufacture of a sheet of anisotropic electrotechnical steel used as a material for iron cores of transformers. In order to manufacture the main silicon steel sheet, a steel slab is heated to a temperature of 1,280°C or lower and hot-rolled, resulting in a hot-rolled steel sheet subjected to annealing in a hot state. The hot-rolled steel sheet is cold-rolled once or twice or more times with intermediate annealing between said times, resulting in a cold-rolled steel sheet subjected to decarbonising annealing and nitriding in the process of nitriding annealing. In the process of cold rolling, the degree of compression in finishing cold rolling is 80% or more, the roughness Ra of the roll in the last pass is 0.40 mcm or less, and the compression in the last pass is 10% or more. An annealing separator containing Al₂O₃ and MgO is applied onto the surface of the decarbonised and annealed sheet, followed by a final annealing with subsequent treatment of the surface by removing the excess annealing separator from the surface of the steel sheet subjected to final annealing, resulting in a main sheet of silicon steel used to manufacture a sheet of anisotropic electrotechnical steel. In the process of final annealing, the oxidation state is 0.0001 to 0.2 when the annealing atmosphere contains hydrogen, or the dew point is 0°C or lower when the annealing atmosphere consists of a hydrogen-free inert gas. In the process of surface treatment, a solution containing less than 20 wt.% total of one or two or more from sulphuric acid, hydrochloric acid, phosphoric acid, nitric acid, hypochlorous acid, an aqueous solution of chromium oxide, chromium sulphate, permanganate, peroxosulphuric, acid and peroxophosphate is used, wherein the temperature of the solution is set to 50–80°C, and the submersion time is set to 1–30 seconds.

EFFECT: manufactured sheets exhibit excellent magnetic characteristics.

12 cl, 3 dwg, 21 tbl, 2 ex

Description

Technical field

[0001] The present invention relates to an anisotropic electrical steel sheet and a method for manufacturing the same, and in particular to an anisotropic electrical steel sheet that exhibits excellent magnetic loss performance due to controlled surface properties of a silicon steel sheet that is a base steel sheet, and to the way it is made. Priority is claimed from Japanese Patent Application No. 2019-5396, filed January 16, 2019, and Japanese Patent Application No. 2019-5398, filed January 16, 2019, the contents of which are incorporated herein by reference.

Background of the invention

[0002] The anisotropic electrical steel sheet contains a silicon steel sheet as a base steel sheet, and is a soft magnetic material that is mainly used as an iron core material of a transformer. Anisotropic electrical steel sheets are required to exhibit excellent magnetic properties. In particular, it is required that excellent magnetic loss characteristics be exhibited.

[0003] Magnetic loss means the loss of energy that occurs when electrical energy and magnetic energy are interconverted. A lower value of magnetic losses is more preferable. Magnetic losses can be roughly divided into two loss components: hysteresis loss and eddy current loss. In addition, eddy current losses can be divided into classical eddy current losses and anomalous eddy current losses.

[0004] For example, attempts have been made to increase the electrical resistance of the silicon steel sheet, to reduce the thickness of the silicon steel sheet, and to insulate the silicon steel sheet with a coating to reduce classical eddy current losses. In addition, attempts have been made to reduce the grain size of the silicon steel sheet, reduce the magnetic domains of the silicon steel sheet, and apply tension to the silicon steel sheet in order to reduce abnormal eddy current losses. In addition, attempts have been made to remove impurities in the silicon steel sheet and to control the crystallographic orientation of the silicon steel sheet in order to reduce the hysteresis loss.

[0005] In addition, attempts have been made to smooth the surface of the silicon steel sheet in order to reduce the hysteresis loss. When the surface of the silicon steel sheet has irregularities, they impede the movement of the domain walls and the occurrence of magnetization becomes less likely. Therefore, attempts have been made to reduce energy loss due to domain wall motion by reducing the surface roughness of the silicon steel sheet.

[0006] For example, Patent Document 1 discloses an anisotropic electrical steel sheet in which excellent magnetic loss characteristics are obtained by smoothing the surface of the steel sheet. Patent Document 1 describes that when the surface of a steel sheet is polished to a mirror finish by chemical polishing or electrolytic polishing, the magnetic loss is greatly reduced.

[0007] Patent Document 2 discloses an anisotropic electrical steel sheet in which the surface roughness Ra of the steel sheet is controlled to be 0.4 µm or less. Patent Document 2 describes that when the surface roughness Ra is 0.4 µm or less, very low magnetic loss is obtained.

[0008] Patent Document 3 discloses an anisotropic electrical steel sheet in which the surface roughness Ra of the steel sheet in the direction perpendicular to the rolling direction is controlled to be 0.15-0.45 µm. Patent Document 3 describes that when the surface roughness in the direction perpendicular to the rolling direction is larger than 0.45 µm, the magnetic loss improvement effect in a strong magnetic field is weakened.

[0009] Patent Document 4 and Patent Document 5 disclose isotropic electrical steel sheets in which the surface roughness Ra is controlled to be 0.2 µm or less when the threshold wavelength lc is 20 µm. Patent Document 4 and Patent Document 5 describe that in order to reduce magnetic loss, it is necessary to eliminate waviness on the long wavelength side of the threshold wavelength, evaluate fine irregularities, and reduce the amount of these fine irregularities.

Citation list

[Patent Documents]

[0010] Patent Document 1: Examined Japanese Patent Application Second Publication No. S52-024499

Patent Document 2: Japan Patent Pending First Publication No. H05-311453

Patent Document 3: Japan Patent Pending First Publication No. 2018-062682

Patent Document 4: Japan Patent Pending First Publication No. 2016-47942

Patent Document 5: Japan Patent Pending First Publication No. 2016-47943

The essence of the invention

Problems solved by the invention

[0011] The inventors have conducted research and as a result found that, as in the like, even if the surface roughness Ra of the silicon steel sheet is controlled to be, for example, 0.40 µm or less, or the surface roughness Ra is controlled so that that it is 0.2 μm or less under the condition of the threshold wavelength λc 20 μm, the magnetic loss characteristics are not always improved sufficiently and stably.

[0012] In addition, in Patent Document 4 and Patent Document 5, in order to improve the magnetic loss characteristics of the isotropic electrical steel sheet, the surface properties of the silicon steel sheet are controlled by cold rolling. However, in the anisotropic electrical steel sheet, unlike the isotropic electrical steel sheet, after cold rolling, decarburization annealing is performed, an annealing separator is applied, final annealing is performed, and refining annealing is further performed at a high temperature for a long time. Therefore, in the anisotropic electrical steel sheet, it is difficult to maintain the surface properties controlled by cold rolling until the end of the last process, in contrast to the isotropic electrical steel sheet. In general, knowledge of isotropic electrical steel sheets cannot simply be applied to anisotropic electrical steel sheet.

[0013] The inventors find it insufficient to control the surface of the anisotropic electrical steel sheets in the prior art, and as a novel perspective postulate that in order to optimally improve the magnetic loss characteristics of the anisotropic electrical steel sheet, it would be necessary to control the surface properties of the silicon steel sheet.

[0014] That is, it is an object of the present invention to provide an anisotropic electrical steel sheet that exhibits excellent magnetic loss characteristics due to optimal control of the surface properties of a silicon steel sheet, which is a base steel sheet, and a manufacturing method thereof.

Solutions to the problem

[0015] The scope of the present invention is as follows.

[0016] (1) An anisotropic electrical steel sheet according to an aspect of the present invention includes a silicon steel sheet as a base steel sheet, and when the average value of the amplitudes in the wavelength range of 20-100 μm among the frequency components obtained by performing Fourier analysis on the measured section curve , parallel to the width direction of the silicon steel sheet, denoted as ave-AMP _C100 , ave-AMP _C100 is 0.0001-0.050 µm.

(2) In the anisotropic electrical steel sheet of (1), ave-AMP _C100 may be 0.0001-0.025 µm.

(3) In the anisotropic electrical steel sheet of (1) or (2), when the maximum amplitude value in the wavelength range of 20-100 µm among the frequency components obtained by performing Fourier analysis on the measured section curve parallel to the width direction of the silicon sheet steel, denoted as max-AMP _C100 , and the maximum value of the amplitudes in the wavelength range of 20-100 μm among the frequency components obtained by performing Fourier analysis on the measured curve of the section parallel to the rolling direction of the silicon steel sheet, denoted as max-AMP _L100 , max -DIV ₁₀₀ , which is the value obtained by dividing max-AMP _C100 by max-AMP _L100 , may be 1.5-6.0.

(4) In the anisotropic electrical steel sheet according to any one of (1) to (3), when the average value of the amplitudes in the wavelength range of 20-50 μm among the frequency components obtained by performing the Fourier analysis is indicated as ave-AMP _C50 , ave -AMP _C50 can be 0.0001-0.035.

(5) In the anisotropic electrical steel sheet of (4), when the maximum amplitude value in the wavelength range of 20-50 µm among the frequency components obtained by performing Fourier analysis on the measured section curve parallel to the width direction of the silicon steel sheet is indicated as max-AMP _C50 , and the maximum value of the amplitudes in the wavelength range of 20-50 μm among the frequency components obtained by performing Fourier analysis on the measured cross-sectional curve parallel to the rolling direction of the silicon steel sheet is designated as max-AMP _L50 , max-DIV ₅₀ , which is a value obtained by dividing max-AMP _C50 by max-AMP _L50 may be 1.5-5.0.

(6) In the anisotropic electrical steel sheet of (4) or (5), ave-AMPC50 may be 0.0001-0.020 µm.

(7) In the anisotropic electrical steel sheet according to any one of (1) to (6), the silicon steel sheet may contain, as chemical components, in mass%, Si: 0.8% or more and 7.0% or less, Mn: 0 or more and 1.00% or less, Cr: 0 or more and 0.30% or less, Cu: 0 or more and 0.40% or less, P: 0 or more and 0.50% or less less, Sn: 0 or more and 0.30% or less, Sb: 0 or more and 0.30% or less, Ni: 0 or more and 1.00% or less, B: 0 or more and 0.008% or less less, V: 0 or more and 0.15% or less, Nb: 0 or more and 0.2% or less, Mo: 0 or more and 0.10% or less, Ti: 0 or more and 0.015% or less less, Bi: 0 or more and 0.010% or less, Al: 0 or more and 0.005% or less, C: 0 or more and 0.005% or less, N: 0 or more and 0.005% or less, S: 0 or less more and 0.005% or less, and Se: 0 or more and 0.005% or less, and the rest is Fe and impurities.

(8) In the anisotropic electrical steel sheet of any one of (1) to (7), the silicon steel sheet may have a texture developed in the {110}<001> orientation.

(9) The anisotropic electrical steel sheet according to any one of (1) to (8) may further include an intermediate layer located in contact with a silicon steel sheet, and this intermediate layer may be a film of silicon oxide.

(10) The anisotropic electrical steel sheet of (9) may further include an insulating coating in contact with the intermediate layer, and the insulating coating may be a phosphoric acid coating.

(11) The anisotropic electrical steel sheet of (9) may further include an insulating coating in contact with the intermediate layer, and the insulating coating is an aluminum borate-based coating.

(12) The method for manufacturing an anisotropic electrical steel sheet according to any one of (1) to (11), including manufacturing an anisotropic electrical steel sheet using a silicon steel sheet as a base.

Invention Effects

[0017] According to the above aspects of the present invention, it is possible to provide an anisotropic electrical steel sheet that exhibits excellent magnetic loss characteristics due to optimal control of the surface properties of the silicon steel sheet, which is the base steel sheet, and the manufacturing method thereof.

Brief description of the drawings

[0018] FIG. 1 shows a graph illustrating amplitude versus wavelength in a Fourier analysis of a measured section curve parallel to the width direction of a silicon steel sheet with respect to an anisotropic electrical steel sheet according to an embodiment of the present invention and a conventional anisotropic electrical steel sheet.

Fig. 2 is a microscopic image showing an example of the magnetic domain structure of an anisotropic electrical steel sheet.

3 shows a graph illustrating amplitude versus wavelength in Fourier analysis of the measured section curve parallel to the width direction of the sheet and the rolling direction of the silicon steel sheet with respect to the anisotropic electrical steel sheet according to the same embodiment.

Embodiment(s) of the invention

[0019] Preferred embodiments of the present invention will be described in detail below. However, the present invention is not limited to only the configuration described in the present embodiment, and can be modified in various ways without deviating from the gist of the present invention. In addition, lower limit values and upper limit values are included in the following limiting ranges of numerical values. Numeric values specified with "greater than" or "less than" are not included in these numerical value ranges. “%” indicating the amount of the corresponding elements means the mass percentage (“wt.%”).

[First Embodiment]

[0020] In the present embodiment, unlike the like, the surface state of the silicon steel sheet, which is the base steel sheet or, in other words, the base steel sheet of the anisotropic electrical steel sheet, is precisely and optimally controlled. More specifically, the surface properties of the silicon steel sheet are monitored in the sheet width direction (C direction) in a wavelength range of 20-100 µm.

[0021] For example, inside a transformer, an anisotropic electrical steel sheet is magnetized with alternating current. Thus, when electric energy and magnetic energy are interconverted in the anisotropic electrical steel sheet, the magnetization direction is reversed mainly in the rolling direction (L direction) in accordance with the alternating current (AC) cycle.

[0022] When the magnetization direction is reversed in the rolling direction, in the anisotropic electrical steel sheet, the domain wall moves back and forth in the generally sheet-width direction according to the AC cycle. Therefore, the inventors believe that, firstly, it is preferable to control the factor that inhibits the movement of the domain walls in the width direction of the sheet.

[0023] In addition, when the domain wall moves back and forth in the sheet width direction according to the AC cycle, considering the size of the magnetic domain in the anisotropic electrical steel sheet, the distance of movement of the domain walls is estimated at about 20-100 µm. 2 shows a microscopic image of examples of the magnetic domain structure of an anisotropic electrical steel sheet. As shown in FIG. 2, the anisotropic electrical steel sheet basically has a striped magnetic domain structure parallel to the rolling direction (L direction). In the anisotropic electrical steel sheet, the width of the magnetic domain in the sheet width direction (C direction) is generally about 20-100 μm. Therefore, the inventors believe that, secondly, it is preferable to control the factor that inhibits the movement of the walls of the domains in the region of 20-100 μm.

[0024] The anisotropic electrical steel sheet of the present embodiment is obtained based on the above detected data. In the present embodiment, among the frequency components obtained by performing the Fourier analysis on the measured section curve parallel to the width direction of the silicon steel sheet (base steel sheet), the amplitude in the wavelength range of 20-100 μm is monitored.

[0025] More specifically, when the average value of the amplitudes in the wavelength range of 20-100 µm among the frequency components obtained by performing the Fourier analysis is indicated as ave-AMP _C100 , ave-AMP _C100 is controlled to be 0.050 µm or less. When ave-AMP _C100 is 0.050 µm or less, the motion of the domain walls is not hampered by the unevenness of the surface, and the domain walls can move appropriately in the width direction of the sheet. As a result, the magnetic loss can be suitably reduced. To further facilitate domain wall movement, ave-AMP _C100 is preferably 0.040 µm or less, more preferably 0.030 µm or less, even more preferably 0.025 µm or less, and most preferably 0.020 µm or less.

[0026] Since a smaller value of ave-AMP _C100 is more preferable, the lower limit of ave-AMP _C100 is not specifically limited. However, since it is not easy in the industry to control ave-AMP _C100 to be less than 0.0001 µm, ave-AMP _C100 may be 0.0001 µm or more.

[0027] In addition, it is preferable to monitor the ave-AMP _C100 value and then monitor the amplitude in the 20-50 µm wavelength range. Because ave-AMP _C100 is an average of amplitudes in the 20-100 µm wavelength range, this value tends to be more easily influenced by high wavelength amplitude in the 20-100 µm range. Therefore, in addition to controlling ave-AMP _C100 , the amplitude in the wavelength range of 20-50 µm is also controlled, and thus the surface properties of the silicon steel sheet can be more appropriately controlled.

[0028] More specifically, when the average value of the amplitudes in the wavelength range of 20-50 µm among the frequency components obtained by performing the Fourier analysis is indicated as ave-AMP _C50 , ave-AMP _C50 is controlled to be 0.035 µm or less. When ave-AMP _C50 is 0.035 µm or less, since the domain walls can more easily move in the sheet width direction, the magnetic loss can be suitably reduced. Ave-AMP _C50 is preferably 0.030 µm or less, more preferably 0.025 µm or less, even more preferably 0.020 µm or less, and most preferably 0.015 µm or less.

[0029] Since a smaller value of ave-AMP _C50 is more preferable, the lower limit of ave-AMP _C50 is not specifically limited. However, since it is not easy in the industry to control ave-AMP _C50 to be less than 0.0001 µm, ave-AMP _C50 may be 0.0001 µm or more.

[0030] FIG. 1 shows a graph obtained when measured curves of a section parallel to the width direction of a silicon steel sheet (base steel sheet) are subjected to Fourier analysis and an amplitude vs. wavelength plot is plotted. As shown in Fig. 1, in the silicon steel sheet of the conventional anisotropic electrical steel sheet, the amplitude is small in the wavelength range of 20 µm or less, but the amplitude is large in the wavelength range of more than 20 µm. More specifically, in the silicon steel sheet of the conventional anisotropic electrical steel sheet, the average amplitude value is 0.02 µm in the wavelength range of 1-20 µm, but the average amplitude value is 0.25 µm in the wavelength range of 20-100 µm. That is, even if the surface properties are controlled microscopically in the wavelength region of 20 µm or less, it is quite clear that the surface properties are not controlled in the wavelength region of 20-100 µm, which is important for the motion of domain walls in the anisotropic electrical steel sheet. On the other hand, as shown in FIG. 1, in the silicon steel sheet of the anisotropic electrical steel sheet of the present embodiment, the amplitude in the wavelength range of 20-100 µm is small. On the other hand, in the silicon steel sheet of the conventional anisotropic electrical steel sheet, the amplitude in the wavelength range of 20-100 μm is of great importance.

[0031] The values of ave-AMP _C100 and ave-AMP _C50 can be measured, for example, in the following way.

[0032] When there is no coating on the silicon steel sheet, the surface properties of the silicon steel sheet can be evaluated directly, and when there is a coating on the silicon steel sheet, the surface properties of the silicon steel sheet can be evaluated after the coating is removed. For example, a coated anisotropic electrical steel sheet can be immersed in a high temperature alkaline solution. More specifically, immersion in an aqueous solution of sodium hydroxide containing NaOH: 20 mass% + H ₂ O: 80 mass% is carried out at 80°C for 20 minutes, and then water washing and drying are carried out, and thus the coating can be removed. (intermediate layer and insulating coating) on a silicon steel sheet. Meanwhile, the immersion time in the aqueous sodium hydroxide solution can be changed according to the thickness of the coating on the silicon steel sheet.

[0033] With respect to the surface properties of the silicon steel sheet, in the contact type surface roughness measuring instrument, the tip radius of the contact needle is generally about a micron (μm), and fine features of the surface shape cannot be detected. Therefore, it is preferable to use a non-contact type surface roughness measuring instrument. For example, a laser-type surface roughness tester (VK-9700 commercially available from Keyence Corporation) can be used.

[0034] First, a measured cross-sectional curve in the width direction of the silicon steel sheet is obtained using a non-contact type surface roughness measuring instrument. When obtaining this measured section curve, the length of one measurement is 500 μm or more, and the total measurement length is 5 mm or more. The spatial resolution in the measurement direction (width direction of the silicon steel sheet) is 0.2 µm or less. The measured section curve is subjected to Fourier analysis without applying a low pass or high pass filter to the measured section curve, ie without cutting out a specific frequency component from the measured section curve.

[0035] Among the frequency components obtained by performing the Fourier analysis on the measured cross-sectional curve, an average value of the amplitudes in the wavelength range of 20-100 μm is obtained. The average value of the amplitudes is denoted as ave-AMP _C100 . Similarly, among the frequency components obtained by performing the Fourier analysis on the measured cross-sectional curve, an average value of the amplitudes in the wavelength range of 20-50 μm is obtained. The average value of the amplitudes is denoted as ave-AMP _C50 . Meanwhile, the above-described measurement and analysis can be carried out at five or more locations, with the measurement locations changing, and their average values can be obtained.

[0036] In the present embodiment, ave-AMP _C100 is controlled, and if necessary, ave-AMP _C50 is controlled to improve magnetic loss performance. The way to control these values of ave-AMP _C100 and ave-AMP _C50 will be described below.

[0037] In addition, in the anisotropic electrical steel sheet of the present embodiment, configurations other than the above surface properties are not specifically limited. However, it is preferable that the anisotropic electrical steel sheet of the present embodiment has the following technical features.

[0038] In the present embodiment, it is preferable that the silicon steel sheet contains the main element as a chemical component and, if necessary, contains selected elements, and the balance is Fe and impurities.

[0039] In the present embodiment, the silicon steel sheet may contain Si as the main element (major alloying element).

Si: 0.8% or more and 7.0% or less

[0040] Si (silicon) is an element that is a chemical component of silicon steel sheet, and is effective for increasing electrical resistance and reducing magnetic loss. When the Si content is more than 7.0%, the material may crack easily during cold rolling and may be difficult to roll. On the other hand, when the Si content is less than 0.8%, the electrical resistance may become small and the magnetic loss in the product may increase. Therefore, Si may be contained in the range of 0.8% or more and 7.0% or less. The lower limit of the Si content is preferably 2.0%, more preferably 2.5%, and even more preferably 2.8%. The upper limit of the Si content is preferably 5.0%, and more preferably 3.5%.

[0041] In the present embodiment, the silicon steel sheet may contain impurities. In this case, “impurities” are those that are mixed in from ore or scrap metal used as raw materials in industrial steel production or from the industrial environment, and the like.

[0042] In addition, in the present embodiment, the silicon steel sheet may contain selected elements in addition to the above base element and impurities. For example, instead of some of Fe from the rest, Mn, Cr, Cu, P, Sn, Sb, Ni, B, V, Nb, Mo, Ti, Bi, Al, C, N, S, and Se. These selected items may be contained as intended. Therefore, there is no need to limit the lower limit value of these selected items, and the lower limit value may be 0%. In addition, if these selected elements are contained as impurities, the above effects are not impaired.

Mn: 0 or more and 1.00% or less

[0043] Mn (manganese), like Si, is an element that is effective for increasing electrical resistance and reducing magnetic loss. In addition, Mn binds to S or Se and acts as an inhibitor. Therefore, Mn may be contained in the range of 1.00% or less. The lower limit of the Mn content is preferably 0.05%, more preferably 0.08%, and even more preferably 0.09%. The upper limit of the Mn content is preferably 0.50%, and more preferably 0.20%.

Cr: 0 or more and 0.30% or less

[0044] Cr (chromium), like Si, is an element that is effective for increasing electrical resistance and reducing magnetic loss. Therefore, Cr may be contained in the range of 0.30% or less. The lower limit of the Cr content is preferably 0.02%, and more preferably 0.05%. The upper limit of the Cr content is preferably 0.20%, and more preferably 0.12%.

Cu: 0 or more and 0.40% or less

[0045] Cu (copper) is also an element that is effective for increasing electrical resistance and reducing magnetic loss. Therefore, Cu may be contained in the range of 0.40% or less. When the Cu content is more than 0.40%, the magnetic loss reduction effect saturates, and a surface defect such as "copper sliver" may be caused during hot rolling. The lower limit of the Cu content is preferably 0.05%, and more preferably 0.10%. The upper limit of the Cu content is preferably 0.30%, and more preferably 0.20%.

P: 0 or more and 0.50% or less

[0046] P (phosphorus) is also an element that is effective for increasing electrical resistance and reducing magnetic loss. Therefore, P may be contained in the range of 0.50% or less. When the P content is more than 0.50%, there may be a problem with the rollability of the silicon steel sheet. The lower limit of the P content is preferably 0.005%, and more preferably 0.01%. The upper limit of the P content is preferably 0.20%, and more preferably 0.15%.

Sn: 0 or more and 0.30% or less

Sb: 0 or more and 0.30% or less

[0047] Sn (tin) and Sb (antimony) are elements that are effective for stabilizing secondary recrystallization and developing the {110}<001> orientation. Therefore, Sn may be contained in the range of 0.30% or less, and Sb may be contained in the range of 0.30% or less. When the content of Sn or Sb is more than 0.30%, it may adversely affect the magnetic properties. The lower limit of the Sn content is preferably 0.02%, and more preferably 0.05%. The upper limit of the Sn content is preferably 0.15%, and more preferably 0.10%. The lower limit of the Sb content is preferably 0.01%, and more preferably 0.03%. The upper limit of the Sb content is preferably 0.15%, and more preferably 0.10%.

Ni: 0 or more and 1.00% or less

[0048] Ni (nickel) is also an element that is effective for increasing electrical resistance and reducing magnetic loss. In addition, Ni is an element that is effective for controlling the metal structure of the hot strip and improving the magnetic properties. Therefore, Ni may be contained in the range of 1.00% or less. When the Ni content is more than 1.00%, the secondary recrystallization may become unstable. The lower limit of the Ni content is preferably 0.01%, and more preferably 0.02%. The upper limit of the Ni content is preferably 0.20%, and more preferably 0.10%.

B: 0 or more and 0.008% or less

[0049] B (boron) is an element that is effective for exhibiting an inhibitory effect as BN. Therefore, B may be contained in the range of 0.008% or less. When the content of B is greater than 0.008%, it may adversely affect the magnetic properties. The lower limit of the B content is preferably 0.0005%, and more preferably 0.001%. The upper limit of the B content is preferably 0.005%, and more preferably 0.003%.

V: 0 or more and 0.15% or less

Nb: 0 or more and 0.2% or less

Ti: 0 or more and 0.015% or less

[0050] V (vanadium), Nb (niobium) and Ti (titanium) are elements effective in binding to N or C and functioning as an inhibitor. Therefore, V may be contained in the range of 0.15% or less, Nb may be contained in the range of 0.2% or less, and Ti may be contained in the range of 0.015% or less. When these elements remain in the final product (electrical steel sheet) and the V content is greater than 0.15%, the Nb content is greater than 0.2%, or the Ti content is greater than 0.015%, magnetic properties may deteriorate. The lower limit of the V content is preferably 0.002%, and more preferably 0.01%. The upper limit of the V content is preferably 0.10%, and more preferably 0.05%. The lower limit of the Nb content is preferably 0.005%, and more preferably 0.02%. The upper limit of the Nb content is preferably 0.1%, and more preferably 0.08%. The lower limit of the Ti content is preferably 0.002%, and more preferably 0.004%. The upper limit of the Ti content is preferably 0.010%, and more preferably 0.008%.

Mo: 0 or more and 0.10% or less

[0051] Mo (molybdenum) is also an element that is effective for increasing electrical resistance and reducing magnetic loss. Therefore, Mo may be contained in the range of 0.10% or less. When the content of Mo is more than 0.10%, there may be a problem with the rollability of the steel sheet. The lower limit of the Mo content is preferably 0.005%, and more preferably 0.01%. The upper limit of the Mo content is preferably 0.08%, and more preferably 0.05%.

Bi: 0 or more and 0.010% or less

[0052] Bi (bismuth) is an element that is effective for stabilizing excretions such as sulfide and improving function as an inhibitor. Therefore, Bi may be contained in the range of 0.010% or less. When the content of Bi is more than 0.010%, it may adversely affect the magnetic properties. The lower limit of the Bi content is preferably 0.001%, and more preferably 0.002%. The upper limit of the Bi content is preferably 0.008%, and more preferably 0.006%.

Al: 0 or more and 0.005% or less

[0053] Al (aluminum) is an element effective in bonding with N and exhibiting an inhibitory effect. Therefore, before final annealing, for example, Al may be contained in the range of 0.01-0.065% in the slab stage. However, if Al remains as an impurity in the final product (electrical steel sheet) and the Al content is more than 0.005%, the magnetic properties may be adversely affected. Therefore, the Al content of the final product is preferably 0.005% or less. The upper limit of the Al content in the final product is preferably 0.004%, and more preferably 0.003%. Meanwhile, the content of Al in the final product corresponds to impurities, the lower limit is not specifically limited, and a smaller content is more preferable. However, since it is not easy in the industry to control the Al content of the final product to be 0%, the lower limit of the Al content of the final product may be 0.0005%. The content of Al indicates the amount of acid-soluble Al.

C: 0 or more and 0.005% or less,

N: 0 or more and 0.005% or less

[0054] C (carbon) is an element that is effective for adjusting primary recrystallization texture and improving magnetic properties. In addition, N (nitrogen) is an element effective in bonding with Al, B or the like. and showing an inhibitory effect. Therefore, before the decarburization annealing, C may be contained in the range of 0.02-0.10%, for example, in the slab stage. In addition, before the final annealing, N may be contained in the range of 0.01-0.05%, for example, at the stage after nitriding annealing. However, when these elements remain as impurities in the final product and the content of each of C and N is greater than 0.005%, magnetic properties may be negatively affected. Therefore, the content of C or N in the final product is preferably 0.005% or less. The content of C or N in the final product is more preferably 0.004% or less, and even more preferably 0.003% or less. In addition, the total amount of C and N in the final product is preferably 0.005% or less. Meanwhile, C and N in the final product are impurities and their content is not specifically limited, and a smaller content is more preferable. However, it is not easy in the industry to control the C or N content of the final product to be 0%, and the C or N content of the final product may be 0.0005% or more.

S: 0 or more and 0.005% or less,

Se: 0 or more and 0.005% or less

[0055] S (sulfur) and Se (selenium) are elements effective in binding to Mn or the like. and showing inhibitory action. Therefore, before final annealing, S and Se may be contained in the range of 0.005-0.050% each, for example, in the slab stage. However, when these elements remain as impurities in the final product and the content of each S and Se is greater than 0.005%, the magnetic properties may be adversely affected. Therefore, the content of S or Se in the final product is preferably 0.005% or less. The content of S or Se in the final product is preferably 0.004% or less, and more preferably 0.003% or less. In addition, the total content of S and Se in the final product is preferably 0.005% or less. Meanwhile, S and Se in the final product are impurities and their content is not specifically limited, and a smaller content is more preferable. However, it is not easy in the industry to control the S or Se content in the final product to be 0%, and the S or Se content in the final product may be 0.0005% or more.

[0056] In the present embodiment, the silicon steel sheet may contain, as selected elements, in mass%, at least one element selected from the group consisting of Mn: 0.05% or more and 1.00% or less, Cr: 0.02% or more and 0.30% or less, Cu: 0.05% or more and 0.40% or less, P: 0.005% or more and 0.50% or less, Sn: 0, 02% or more and 0.30% or less, Sb: 0.01% or more and 0.30% or less, Ni: 0.01% or more and 1.00% or less, B: 0.0005% or more and 0.008% or less, V: 0.002% or more and 0.15% or less, Nb: 0.005% or more and 0.2% or less, Mo: 0.005% or more and 0.10% or less, Ti: 0.002% or more and 0.015% or less, and Bi: 0.001% or more and 0.010% or less.

[0057] The chemical components of the silicon steel sheet described above can be measured by a conventional analysis method. For example, a steel component can be measured using inductively coupled plasma atomic emission spectrometry (ICP-AES). Meanwhile, C and S can be measured using the infrared absorption method after combustion, N can be measured using the heat conduction method when melting in an inert gas, and O can be measured using a non-dispersive infrared absorption method when melting in an inert gas.

[0058] In addition, it is preferable that the silicon steel sheet of the anisotropic electrical steel sheet of the present embodiment has a texture developed in the {110}<001> orientation. The {110}<001> orientation means a crystallographic orientation (Goss orientation) in which the {110} planes are aligned parallel to the surface of the steel sheet and the <100> axes are aligned in the rolling direction. When the silicon steel sheet is controlled in the Goss orientation, the magnetic properties are preferably improved.

[0059] The texture of the silicon steel sheet described above can be measured by a conventional analysis method. For example, it can be measured using x-ray diffraction (Laue method). The Laue method is a method of vertically irradiating a steel sheet with an X-ray beam and analyzing the diffraction spots of transmitted or reflected radiation. When conducting an analysis diffraction spots, you can identify the crystallographic orientation of the location that is irradiated with an x-ray beam. When diffraction spots are analyzed at multiple locations while changing the irradiation position, the distribution of crystallographic orientations at each irradiation position can be measured. The Laue method is a method suitable for measuring the crystallographic orientation of a metal structure containing large crystalline grains.

[0060] In addition, the anisotropic electrical steel sheet of the present embodiment may have an interlayer in contact with the silicon steel sheet, or may have an insulating coating in contact with the interlayer.

[0061] The intermediate layer is a silicon oxide film and contains silicon oxide as a main component, and has a film thickness of 2 nm or more and 500 nm or less. The intermediate layer extends continuously over the surface of the silicon steel sheet. When the intermediate layer is formed between the silicon steel sheet and the insulation coating, the adhesion between the silicon steel sheet and the insulation coating is improved, and stress can be applied to the silicon steel sheet. In the present embodiment, the interlayer is not a forsterite coating, but is preferably an interlayer (silica film) mainly containing silicon oxide.

[0062] The intermediate layer is formed by heating a silicon steel sheet in which the formation of the forsterite coating is limited during the final annealing or the forsterite coating is removed after the final annealing in a gas atmosphere that is adjusted to a predetermined oxidation state (PH ₂ O/PH ₂ ). In the present embodiment, the intermediate layer is preferably an externally oxidized layer formed by external oxidation.

[0063] Meanwhile, external oxidation is an oxidation that occurs in a gas atmosphere with a low oxidation state, and means oxidation in such a form that an alloying element (Si) in the steel sheet diffuses to the surface of the steel sheet and then forms on the surface of the steel sheet film oxide. On the other hand, internal oxidation is an oxidation that occurs in a gas atmosphere with a relatively high oxidation state, and means oxidation in a form in which the alloying element in the steel sheet hardly diffuses to the surface, the oxygen present in the atmosphere diffuses into the steel sheet, and then dispersed in the form of islands in the steel sheet, and an oxide is formed.

[0064] The intermediate layer contains silica (silicon oxide) as the main component. The intermediate layer may contain oxides of the alloying elements contained in the silicon steel sheet in addition to silicon oxide. That is, it may contain any oxide of Fe, Mn, Cr, Cu, Sn, Sb, Ni, V, Nb, Mo, Ti, Bi, and Al, or a composite oxide thereof. In addition, it may contain metal grains such as Fe. In addition, impurities may be contained, provided that the effects are not impaired.

[0065] The average thickness of the intermediate layer is preferably 2 nm or more and 500 nm or less. When the average thickness is less than 2 nm or more than 500 nm, this is not preferable because the adhesion between the silicon steel sheet and the insulation coating decreases, and sufficient voltage cannot be applied to the silicon steel sheet, and the magnetic loss increases. The lower limit of the average film thickness of the intermediate layer is preferably 5 nm. The upper limit of the average film thickness of the intermediate layer is preferably 300 nm, more preferably 100 nm, and even more preferably 50 nm.

[0066] The crystal structure of the intermediate layer is not particularly limited. However, the intermediate layer matrix phase is preferably amorphous. When the matrix phase of the intermediate layer is amorphous, the adhesion between the silicon steel sheet and the insulation coating can be preferably improved.

[0067] In addition, the insulating coating in contact with the intermediate layer is preferably a phosphoric acid coating or an aluminum borate coating.

[0068] When the insulation coating is a phosphoric acid coating, the phosphoric acid coating preferably contains a phosphorus-silicon composite oxide (a composite oxide containing phosphorus and silicon) and has a film thickness of 0.1 µm or more and 10 µm or less. The phosphoric acid coating extends continuously over the surface of the intermediate layer. When a phosphoric acid coating is formed in contact with the intermediate layer, it is possible to further apply tension to the silicon steel sheet and appropriately reduce the magnetic loss.

[0069] The phosphoric acid coating may contain an oxide of the alloying elements contained in the silicon steel sheet in addition to the phosphorus-silicon composite oxide. That is, it may contain any oxide of Fe, Mn, Cr, Cu, Sn, Sb, Ni, V, Nb, Mo, Ti, Bi, and Al, or a composite oxide thereof. In addition, it may contain metal grains such as Fe. In addition, impurities may be contained, provided that the effects are not impaired.

[0070] The average thickness of the phosphoric acid coating is preferably 0.1 µm or more and 10 µm or less. The upper limit of the average thickness of the phosphoric acid coating is preferably 5 µm, and more preferably 3 µm. The lower limit of the average thickness of the phosphoric acid coating is preferably 0.5 µm, and more preferably 1 µm.

[0071] The crystal structure of the phosphoric acid coating is not particularly limited. However, the phosphoric acid coating matrix phase is preferably amorphous. When the matrix phase of the phosphoric acid coating is amorphous, the adhesion between the silicon steel sheet and the phosphoric acid coating can be suitably improved.

[0072] In addition, when the insulation coating is an aluminum borate coating, the aluminum borate coating preferably contains aluminum boron oxide and has a film thickness greater than 0.5 μm and 8 μm or less. The aluminum borate coating extends continuously over the surface of the intermediate layer. When an aluminum borate-based coating is formed in contact with the intermediate layer, it is possible to further apply tension to the silicon steel sheet and appropriately reduce the magnetic loss. For example, an aluminum borate coating can apply 1.5 to 2 times more tension on a silicon steel sheet than a phosphoric acid coating.

[0073] The aluminum borate coating may contain crystalline Al ₁₈ B ₄ O ₃₃ , Al ₄ B ₂ O ₉ , alumina, or boron oxide in addition to aluminum boron oxide. In addition, it may contain metal grains such as Fe or an oxide. In addition, impurities may be contained, provided that the effects are not impaired.

[0074] The average thickness of the aluminum borate coating is preferably greater than 0.5 µm and 8 µm or less. The upper limit of the average thickness of the aluminum borate coating is preferably 6 µm, and more preferably 4 µm. The lower limit of the average thickness of the aluminum borate coating is preferably 1 µm, and more preferably 2 µm.

[0075] The crystal structure of the aluminum borate coating is not particularly limited. However, the aluminum borate coating matrix phase is preferably amorphous. When the matrix phase of the aluminum borate coating is amorphous, the adhesion between the silicon steel sheet and the aluminum borate coating can be suitably improved.

[0076] The coating pattern of the above anisotropic electrical steel sheet can be observed, for example, by the following method.

[0077] An examination specimen is cut from an anisotropic electrical steel sheet, and the layer structure of the examination specimen is observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). For example, a layer with a thickness of 300 nm or more can be observed with SEM, and a layer with a thickness of less than 300 nm can be observed with TEM.

[0078] More specifically, first, the test piece is cut so that the cutting direction is parallel to the sheet thickness direction (specifically, the test piece is cut so that the cut surface is parallel to the sheet thickness direction and perpendicular to the rolling direction), and the section structure of the cut surface is observed. using SEM at such a magnification that each layer is in the observed field of view. For example, when observing on a composite image in back-scattered electrons (the COMPO image), one can find out the number of layers that make up the cross-sectional structure. For example, in a COMPO image, a silicon steel sheet may be identified as a light color, an intermediate layer may be identified as a dark color, and an insulating coating (aluminum borate coating or phosphoric acid coating) may be identified as a neutral color.

[0079] To describe each layer in the cross-sectional structure using energy dispersive X-ray spectroscopy (SEM-EDS), a linear analysis is performed in the sheet thickness direction, and a quantitative analysis of the chemical components of each layer is performed. The elements to be quantified are 6 elements: Fe, P, Si, O, Mg, and Al. The apparatus used herein is not particularly limited, but in the present embodiment, for example, SEM (NB5000, commercially available from Hitachi High-Technologies Corporation), EDS (XFlash(r) 6|30, commercially available from Bruker AXS), and software EDS analysis software (ESPRIT1.9, commercially available from Bruker AXS).

[0080] Based on the observation results of the COMPO images and the results of the SEM-EDS quantitative analysis described above, if there is a layered region present at the deepest position in the sheet thickness direction, which is the region in which the Fe content is 80 atomic % or more and the O content is less than 30 atomic %, excluding measurement noise, and the line segment (thickness) corresponding to this area on the scan line in the case of linear analysis is 300 nm or more, this area is defined as silicon steel sheet, and the area excluding silicon steel sheet is defined as an intermediate layer and an insulating coating (aluminum borate coating or phosphoric acid coating).

[0081] With respect to the region other than the above silicon steel sheet, based on the observation results of the COMPO images and the results of the SEM-EDS quantitative analysis, if there is a region in which the Fe content is less than 80 atomic %, the P content is 5 atomic % or more, and the O content is 30 atomic % or more excluding measurement noise, and the line segment (thickness) corresponding to this region on the scan line in the case of linear analysis is 300 nm or more, this region is defined as a phosphoric acid coating. Meanwhile, in addition to the above three elements that are defining elements for describing the phosphoric acid coating, the phosphoric acid coating may contain aluminum, magnesium, nickel, manganese or the like derived from phosphate. In addition, silicon originating from colloidal silicon dioxide and the like may also be contained. Meanwhile, in the present embodiment, the phosphoric acid coating may not be provided.

[0082] Regarding the area except for the above silicon steel sheet and phosphoric acid coating, based on the observation results of COMPO images and the results of SEM-EDS quantitative analysis, if there is an area in which the Fe content is less than 80 atomic %, the P content is less than 5 atomic %, the Si content is less than 20 atomic %, the O content is 20 atomic % or more, and the Al content is 10 atomic % or more, excluding measurement noise, and the corresponding line segment (thickness) on the scan line in If linear analysis is 300 nm or more, then this region is defined as an aluminum borate coating. Here, in addition to the five elements that are defining elements for describing the aluminum borate coating, the aluminum borate coating contains boron. However, it may be difficult to accurately analyze the amount of boron by quantitative EDS analysis due to the influence of carbon and the like. Therefore, if necessary, a qualitative EDS analysis can be performed to determine whether the aluminum borate coating contains boron. Meanwhile, in the present embodiment, the aluminum borate coating may not be provided.

[0083] When the area corresponding to the phosphoric acid coating or the aluminum borate coating is determined, the exudates, inclusions, voids, etc. contained in each coating are not included in the purpose of the determination, and the area that satisfies the above results as a matrix phase, defined as a phosphoric acid coating or an aluminum borate coating. For example, based on COMPO images or linear analysis results, if it is confirmed that highlights, inclusions, voids, etc. are present on the scan line in the case of linear analysis, this area is not included in the target area, and the determination is carried out from the results of quantitative analysis as a phase of the matrix. At the same time, highlights, inclusions, and voids can be distinguished from the matrix phase by contrast in COMPO images, and can also be distinguished from the matrix phase by the occurrence of constituent elements in the results of quantitative analysis. Meanwhile, when describing a phosphoric acid coating or an aluminum borate coating, it is preferable to carry out the description at that position on the scan line in the case of a linear analysis in which precipitates, inclusions, and voids are not included.

[0084] If there is a region other than the above silicon steel sheet and insulation coating (aluminum borate coating or phosphoric acid coating), and the corresponding linear segment (thickness) on the scan line in the case of linear analysis is 300 nm or more, then this area is defined as an intermediate layer. Meanwhile, in the present embodiment, the intermediate layer may not be provided.

[0085] The intermediate layer can satisfy, as an overall average, an average Fe content of less than 80 atomic %, an average P content of less than 5 atomic %, an average Si content of 20 atomic % or more, and an average O content of 30 atomic % or more. In addition, if the intermediate layer is not a forsterite coating but a silica film mainly containing silicon oxide, the average Mg content in the intermediate layer may be less than 20 atomic %. Meanwhile, the results of the quantitative analysis of the intermediate layer are the results of quantitative analysis as a phase of the matrix, which do not include the results of the analysis of precipitates, inclusions, voids, etc. contained in the intermediate layer. However, when describing the intermediate layer, it is preferable to carry out the description at that position on the scan line in the case of linear analysis, in which highlights, inclusions, and voids are not included.

[0086] Description of each layer and measurement of thickness using the above observation of COMPO images and quantitative SEM-EDS analysis is carried out at five or more locations with different observed fields of view. For the thickness of each layer obtained at five or more locations in total, an average of the values excluding the maximum value and the minimum value is obtained, and this average value is used as the average thickness of each layer. However, for the thickness of the intermediate layer, the thicknesses are measured at locations that can be determined as an external oxidation region rather than an internal oxidation region, while observing the morphology, and an average value of the thicknesses is obtained.

[0087] In this case, if there is a layer in which the linear segment (thickness) on the scan line in the case of linear analysis is less than 300 nm in at least one observed field of view at the above five or more locations, then the corresponding layer is observed in detail using TEM and the corresponding layer describe and measure its thickness using TEM.

[0088] The examination specimen containing the layer to be observed in detail using TEM is cut by FIB processing so that the cutting direction is parallel to the thickness direction of the sheet (more specifically, the examination specimen is cut so that the cut surface is parallel to the direction across the thickness of the sheet and perpendicular to the rolling direction), and the cross-sectional structure of the cut surface is observed (bright-field image) using scanning TEM (STEM) at such a magnification that the corresponding layer is within the observed field of view. When not every layer is within the observed field of view, the cross-sectional pattern is observed over a plurality of continuous fields of view.

[0089] In order to describe each layer in the cross-sectional structure using TEM-EDS, a linear analysis is performed in the thickness direction of the sheet, and a quantitative analysis of the chemical components of each layer is performed. The elements to be quantified are 6 elements: Fe, P, Si, O, Mg and Al. The apparatus used herein is not particularly limited, but in the present embodiment, for example, TEM (JEM-2100F, commercially available from JEOL Ltd.), EDS (JED-2300T, commercially available from JEOL Ltd.), and analysis software can be used. EDS (AnalysisStation, commercially available from JEOL Ltd.).

[0090] Based on the results of observation of bright-field images obtained using TEM, and the results of quantitative analysis obtained using TEM-EDS, described above, each layer is described and the thickness of each layer is measured. The method for describing each layer and the method for measuring the thickness of each layer using TEM can be carried out according to the above method using SEM.

[0091] Meanwhile, when the thickness of each layer described using TEM is 5 nm or less, it is preferable to use a TEM having a function for correcting spherical aberration considering spatial resolution. In addition, when the thickness of each layer is 5 nm or less, a point analysis is performed in the sheet thickness direction, for example, at intervals of 2 nm or less, a linear segment (thickness) of each layer is measured, and this linear segment can be used as the thickness of each layer. . For example, using a TEM having a spherical aberration correction function, EDS analysis can be performed with a spatial resolution of about 0.2 nm.

[0092] Meanwhile, in the results of quantitative analysis of the chemical components of the phosphoric acid coating described by the above method, if the content of Fe is less than 80 atomic%, the content of P is 5 atomic% or more, and the content of O is 30 atomic% or more, determine that the coating based on phosphoric acid mainly contains a complex oxide of phosphorus-silicon.

[0093] Similarly, in the results of quantitative analysis of the chemical components of the aluminum borate coating described by the above method, if the Fe content is less than 80 atomic%, the P content is less than 5 atomic %, the Si content is less than 20 atomic %, the O content is 20 atomic %. % or more and the Al content is 10 atomic % or more, and boron is detected by qualitative analysis, it is determined that the aluminum borate coating mainly contains aluminum boron oxide.

[0094] Similarly, in the results of quantitative analysis of the chemical components of the intermediate layer described by the above method, if the average content of Fe is less than 80 atomic %, the average content of P is less than 5 atomic %, the average content of Si is 20 atomic % or more, the average content of O is 30 atomic % or more and the average content of Mg is less than 20 atomic %, it is determined that the intermediate layer mainly contains silicon oxide.

[0095] In the following method, it is determined whether the aluminum borate coating contains alumina, Al ₁₈ B ₄ O ₃₃ , Al ₄ B ₂ O ₉ , boron oxide, or the like. A sample is cut from a sheet of anisotropic electrical steel and, if necessary, polished so that a surface parallel to the surface of the sheet becomes the measurement surface, the aluminum borate coating is exposed, and X-ray diffraction measurement is performed. For example, X-ray diffraction can be performed using CoKb (Kb1) radiation as the incident X-ray. Based on the X-ray diffraction pattern, whether alumina, Al ₁₈ B ₄ O ₃₃ , Al ₄ B ₂ O ₉ , boron oxide, or the like is present is identified.

[0096] The above identification can be performed using a powder diffraction file (PDF) of the International Center for Diffraction Data (ICDD). Alumina identification can be done based on PDF No. 00-047-1770 or 00-056-1186. The identification of Al ₁₈ B ₄ O ₃₃ can be made on the basis of PDF no. 00-029-0009, 00-053-1233 or 00-032-0003. The identification of Al ₄ B ₂ O ₉ can be made based on PDF No. 00-029-0010. Boron oxide identification can be done based on PDF No. 00-044-1085, 00-024-0160 or 00-006-0634.

[0097] Next, the manufacturing method of the anisotropic electrical steel sheet of the present embodiment will be described.

[0098] Meanwhile, the manufacturing method of the anisotropic electrical steel sheet of the present embodiment is not limited to the following method. The following manufacturing method is one example of manufacturing the anisotropic electrical steel sheet of the present embodiment.

[0099] For example, a method for manufacturing an anisotropic electrical steel sheet includes a casting process, a heating process, a hot rolling process, a hot strip state annealing process, a hot strip pickling process, a cold rolling process, a decarburization annealing process, a nitriding process, an annealing separator coating process, finishing annealing process, surface treatment process, intermediate layer forming process, insulation coating forming process, and magnetic domain driving process.

[0100] Since the anisotropic electrical steel sheet of the present embodiment has the surface properties of a silicon steel sheet as a base, among the above manufacturing processes of the anisotropic electrical steel sheet, it is particularly preferable to control four processes: a cold rolling process, a decarburization annealing process, a finishing annealing process, and a machining process. surfaces that affect the surface properties of the silicon steel sheet. The preferred manufacturing method will be described below in order starting from the casting process.

casting process

[0101] In the casting process, steel containing the above chemical components can be melted in a converter furnace, an electric furnace, or the like, and the molten steel can be used to produce a slab. The slab may be produced by a continuous casting process, or an ingot may be produced using molten steel, and the ingot may be bloomed to form a slab. In addition, the slab can be obtained in another way. The thickness of the slab is not particularly limited and is, for example, 150-350 mm. The thickness of the slab is preferably 220-280 mm. The so-called thin slab with a thickness of 10-70 mm can be used as a slab.

heating process

[0102] In the heating process, the slab may be placed in a well-known heating furnace or a well-known holding furnace and heated. As one method for heating the slab, the slab may be heated at 1280°C or lower. When the heating temperature of the slab is set to 1280°C or lower, various problems (necessity of a special heating furnace, large amount of molten scale, and the like) occurring, for example, when heating is carried out at a temperature above 1280°C, can be avoided. The lower limit value of the slab heating temperature is not specifically limited. When the heating temperature is too low, hot rolling may become difficult and productivity may decrease. Therefore, the heating temperature can be set in the range of 1280°C or lower depending on the capacity. The preferred lower limit of the slab heating temperature is 1100°C. The preferred upper limit of the slab heating temperature is 1250°C.

[0103] In addition, as another way of heating the slab, the slab may be heated at a temperature of 1320°C or higher. When heating is carried out at a high temperature of 1320° C. or higher, AlN and Mn (S, Se) dissolve and form fine precipitates in the subsequent process, and secondary recrystallization can be stably exhibited. In this case, the slab heating process itself can be excluded, and hot rolling can begin after casting and before the temperature of the slab decreases.

hot rolling process

[0104] In the hot rolling process, the slab may be hot rolled using a hot rolling mill. The hot rolling mill includes, for example, a rough rolling mill and a finishing mill downstream of the rough rolling mill. The heated steel is rolled in a rough rolling mill and then further rolled in a finishing mill to obtain a hot rolled steel sheet. The end temperature (the temperature of the steel sheet at the outlet side of the finishing stand which last rolls the steel sheet in the finishing mill) in the hot rolling process may be 700-1150°C.

Annealing process in hot strip condition

[0105] In the hot strip state annealing process, the hot-rolled steel sheet may be annealed (hot strip state annealing). By annealing in the hot strip state, the inhomogeneous structure generated during hot rolling is made as uniform as possible. The annealing conditions are not particularly limited as long as the inhomogeneous structure generated during hot rolling can be made uniform. For example, a hot-rolled steel sheet is annealed under conditions of a holding temperature of 750-1200°C and a holding time of 30-600 seconds. However, it is not always necessary to carry out hot strip annealing, and whether or not to carry out the hot strip annealing process may depend on the desired characteristics of the finally obtained anisotropic electrical steel sheet and the production cost. In addition to making the structure uniform, two-stage annealing, rapid cooling after annealing, and the like can be performed to control the formation of AlN inhibitor fine precipitates and control carbon in solid solution and secondary phases. known way.

hot strip pickling process

[0106] In the pickling process of the hot strip, pickling may be carried out to remove scale formed on the surface of the hot-rolled steel sheet. The etching conditions during hot strip etching are not particularly limited, and etching can be carried out under known conditions.

cold rolling process

[0107] In the cold rolling process, the hot rolled steel sheet may be cold rolled one or two or more times with intermediate annealing in between. The reduction ratio in finish cold rolling during cold rolling (the total cold rolling reduction ratio without intermediate annealing or the total cold rolling reduction ratio after intermediate annealing is carried out) is preferably 80% or more, and more preferably 90% or more. In addition, the reduction ratio in finishing cold rolling during cold rolling is preferably 95% or less. Here, the reduction ratio in finish cold rolling (%) is determined as follows: reduction ratio in cold rolling (%)=(1-thickness of steel sheet after finish cold rolling/thickness of steel sheet before finish cold rolling)×100.

[0108] In the present embodiment, from the properties of the surface of the roll in the last pass (finishing stand) in cold rolling, the arithmetic mean Ra is 0.40 µm or less, and more preferably, the mean value of ave-AMP _C100 amplitudes in the wavelength range of 20 -100 µm among the frequency components obtained by Fourier analysis is 0.050 µm or less, and the reduction in the last pass (finishing stand) is preferably 10% or more. When the rolling roll in the last pass is smoother and the reduction in the last pass is larger, it becomes easier to control the surface smoothness of the silicon steel sheet as a result. When the above conditions are satisfied in cold rolling and the control conditions in post-processing are satisfied, ave-AMP _C100 , etc. the silicon steel sheet can be suitably controlled.

Decarburizing Annealing Process

[0109] In the decarburization annealing process, the cold-rolled steel sheet may be annealed in a decarburizing atmosphere. By means of decarburization annealing, the carbon present in the steel sheet is removed and primary recrystallization also takes place. In decarburization annealing, the oxidation state (PH ₂ O/PH ₂ ) in the annealing atmosphere (furnace atmosphere) can be 0.01-0.15, the holding temperature can be 750-900°C, and the holding time can be 10-600 seconds .

[0110] In the present embodiment, the above-described decarburization annealing conditions are controlled, and the amount of oxygen on the surface of the decarburized and annealed sheet is controlled to be 1 g/m ² or less. For example, when the oxidation state is high in the above range, the holding temperature is lowered in the above range or the holding time is shortened in the above range, and the amount of oxygen on the surface of the steel sheet can be 1 g/m ² or less. In addition, for example, when the holding temperature is high, being in the above range, the oxidation state is lowered in the above range or the holding time is shortened in the above range, and the amount of oxygen on the surface of the steel sheet can be 1 g/m ² or less. Here, even if pickling is carried out using sulfuric acid, hydrochloric acid or the like after the decarburization annealing, it is not at all easy to control the amount of oxygen on the surface of the decarburized and annealed sheet to be 1 g/m ² or less. It is preferable to control the amount of oxygen on the surface of the decarburized and annealed sheet by controlling the decarburization annealing conditions described above.

[0111] The amount of oxygen on the surface of the decarburized and annealed sheet is preferably 0.8 g/m ² or less. When the amount of oxygen is smaller, it eventually becomes easier to control the surface smoothness of the silicon steel sheet. When the above conditions are satisfied in the decarburization annealing process and the control conditions in pre-processing (in the upstream process) and post-processing (in the downstream process) are satisfied, ave-AMP _C100 , etc. the silicon steel sheet can be suitably controlled.

Nitriding process

[0112] In the nitriding process, the decarburized and annealed sheet may be annealed and nitrided in an atmosphere containing ammonia. This nitriding treatment can be continued directly after the decarburization annealing without lowering the temperature of the steel sheet after the decarburization annealing to room temperature. When nitriding treatment is carried out, since fine inhibitors such as AlN and (Al,Si)N are formed in the steel, secondary recrystallization can occur stably.

[0113] The nitriding treatment conditions are not particularly limited, but it is preferable to perform nitriding such that the nitrogen content of the steel is increased by 0.003% or more after nitriding than before. The nitrogen content increment before and after nitriding is preferably 0.005% or more, and more preferably 0.007% or more. When the increment of nitrogen before and after nitriding is more than 0.030%, the effect is maximized. Therefore, nitriding can be carried out such that the increment of nitrogen is 0.030% or less.

Annealing Separator Application Process

[0114] In the process of applying the annealing separator, an annealing separator containing Al ₂ O ₃ and MgO is applied to the surface of the decarburized and annealed sheet, and the applied annealing separator can be dried. The annealing separator may be applied to the surface of the steel sheet by water slurry coating, electrostatic coating, or the like.

[0115] When the annealing separator mainly contains MgO and the amount of Al ₂ O ₃ is small, a forsterite coating is formed on the steel sheet during the final annealing. On the other hand, when the annealing separator mainly contains Al ₂ O ₃ and the amount of MgO is small, mullite (3Al ₂ O ₃ ·2SiO ₂ ) is formed on the steel sheet. Since these forsterite and mullite impede the movement of the domain walls, the magnetic loss characteristics of the anisotropic electrical steel sheet deteriorate.

[0116] If an annealing separator containing Al ₂ O ₃ and MgO in a preferred ratio is used, it is possible to obtain a steel sheet having a smooth surface without the formation of forsterite or mullite during final annealing. For example, the annealing separator may contain 5-50% MgO/(MgO+Al ₂ O ₃ ), which is a weight ratio of MgO and Al ₂ O ₃ , and 1.5 wt.% or less water of hydration.

Final annealing process

[0117] In the final annealing process, the cold-rolled steel sheet to which the annealing separator is applied may be subjected to final annealing. When the final annealing is performed, secondary recrystallization occurs and the crystallographic orientation of the steel sheet in the {110}<001> orientation is accumulated. In the final annealing heating procedure, when the annealing atmosphere (furnace atmosphere) contains hydrogen to stably carry out secondary recrystallization, the oxidation state (PH ₂ O/PH ₂ ) is set to 0.0001-0.2, and in the case of an atmosphere containing an inert gas and free of hydrogen, the dew point may be 0°C or lower.

[0118] In the present embodiment, with regard to high-temperature holding conditions for final annealing, in an atmosphere containing 50 vol% or more of hydrogen, the holding temperature is 1100-1250°C. In addition, when the holding temperature is 1100-1150°C, the holding time is 30 hours or more. In addition, when the holding temperature is higher than 1150-1250°C, the holding time is 10 hours or more. When the holding temperature is higher or the holding time is longer, it eventually becomes easier to control the surface smoothness of the silicon steel sheet. However, when the holding temperature is higher than 1250°C, the equipment becomes expensive. When the above conditions are satisfied in the final annealing process and the control conditions in pre-processing and post-processing are satisfied, ave-AMP _C100 , etc. silicon steel sheet can be controlled appropriately.

[0119] Meanwhile, in the final annealing, elements such as Al, N, S, and Se contained in the steel composition of the cold-rolled steel sheet are released, and the steel sheet is refined.

Surface treatment process

[0120] In the surface treatment process, the steel sheet after final annealing (finally annealed steel sheet) can be pickled and then washed with water. The pickling and water washing treatment is carried out to remove excess annealing separator which has not reacted with steel from the surface of the steel sheet, and the surface properties of the steel sheet can be suitably controlled. Meanwhile, the steel sheet after the surface treatment process is a silicon steel sheet as the base of the anisotropic electrical steel sheet.

[0121] In the present embodiment, with respect to the etching conditions for surface treatment, it is preferable to use a solution containing a total amount of less than 20 mass% of one or two or more of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, chloric acid, aqueous solution chromium oxide, chromium sulfate, permanganate, peroxosulfuric acid and peroxophosphate. More preferably 10% by weight or less. Using this solution, etching is carried out under conditions of high temperature and short time. More specifically, pickling is carried out when the temperature of the solution is set to 50-80°C and the immersion time is set to 1-30 seconds. When the pickling is carried out under such conditions, the excess annealing separator on the surface of the steel sheet can be effectively removed, and the surface properties of the steel sheet can be suitably controlled. In the above range, when the acid concentration is lower, the liquid temperature is lower, the immersion time is shorter, pickling pits formed on the surface of the steel sheet are limited, and as a result, it becomes easier to control the surface smoothness of the silicon steel sheet. When the above conditions are satisfied in the surface treatment process and the pretreatment control conditions are satisfied, ave-AMP _C100 , etc. the silicon steel sheet can be suitably controlled. Meanwhile, the conditions for washing with water in the surface treatment are not particularly limited, and washing can be carried out under known conditions.

[0122] In the present embodiment, it is possible to manufacture an anisotropic electrical steel sheet containing the silicon steel sheet obtained above as a base. More specifically, an anisotropic electrical steel sheet can be produced using a silicon steel sheet as a base, in which the average value of the amplitudes in the wavelength range of 20-100 μm among the frequency components obtained by performing Fourier analysis on the measured section curve parallel to the width direction of the sheet, is 0.0001-0.050 µm. Preferably, an intermediate layer and an insulating coating can be formed on the surface of the silicon steel sheet, using the above silicon steel sheet as a base for manufacturing the anisotropic electrical steel sheet.

The process of forming the intermediate layer

[0123] In the process of forming the intermediate layer, the above silicon steel sheet can be kept in a gas atmosphere that contains hydrogen and has an oxidation state (PH ₂ O/PH ₂ ) that is adjustable at 0.00008-0.012, in the temperature range of 600°C or higher and 1150°C or lower for 10 seconds or more and 100 seconds or less. According to this heat treatment, an intermediate layer is formed on the surface of the silicon steel sheet as an externally oxidized layer.

The process of forming an insulating coating

[0124] In the process of forming the insulating coating on the silicon steel sheet on which the intermediate layer is formed, an insulating coating (phosphoric acid coating or aluminum borate coating) can be formed.

[0125] When forming a phosphoric acid coating, a phosphoric acid coating composition containing a mixture of colloidal silicon dioxide, a phosphate such as a metal phosphate, and water is applied and calcined. The phosphoric acid coating composition may contain 25-75 wt.% phosphate and 75-25 wt.% colloidal silicon dioxide in terms of anhydrous compounds. The phosphate may be an aluminum salt, a magnesium salt, a nickel salt, a manganese salt, or the like. and phosphoric acid. The phosphoric acid coating is formed by calcining the phosphoric acid coating composition at 350-600°C and then heating at 800 to 1000°C. During such heat treatment, the oxidation state and dew point and the like can be controlled as necessary. atmosphere.

[0126] When forming an aluminum borate coating, an aluminum borate coating composition containing an aluminum oxide sol (aluminosol) and boric acid is applied and calcined. The composition for forming a coating based on aluminum borate may have a composition ratio between aluminum sol and boric acid, which is 1.25-1.81 in terms of the atomic ratio (Al/B) between aluminum and boric acid. The aluminum borate coating is formed by heating with a holding temperature of 750-1350°C and a holding time of 10-100 seconds. During such heat treatment, the oxidation state, atmospheric dew point, and the like can be controlled as necessary. atmosphere.

Magnetic domain management process

[0127] In the magnetic domain driving process, magnetic domain refinement processing can be carried out on the silicon steel sheet. When a non-destructive stress strain is applied in a direction crossing the rolling direction of the silicon steel sheet or a physical groove is formed, the magnetic domains of the silicon steel sheet may be refined. For example, stress strain may be applied by laser beam irradiation, electron beam irradiation, or the like. The groove can be created by a mechanical method such as a gear, a chemical method such as etching, or a thermal method such as laser irradiation.

[0128] When a non-destructive stress strain is applied to the silicon steel sheet to refine the magnetic domains, it is preferable to control the magnetic domains after the insulating coating forming process. On the other hand, when a physical groove is formed in the silicon steel sheet to refine the magnetic domains, it is preferable to control the magnetic domains between the cold rolling process and the decarburization annealing process, between the decarburization annealing process (nitriding process) and the annealing separator deposition process, between the intermediate layer forming process and the process of forming an insulating coating or after the process of forming an insulating coating.

[0129] As described above, in the present embodiment, when the conditions for the four processes including the cold rolling process, the decarburization annealing process, the final annealing process, and the surface treatment process are controlled, the surface properties of the silicon steel sheet can be controlled. Since each of the conditions for these four processes is a control condition for controlling the surface properties of the silicon steel sheet, it is not enough to satisfy only one condition. Unless these conditions are controlled simultaneously and collectively, ave-AMP _C100 silicon steel sheet cannot be met.

[Second Embodiment]

[0130] In the anisotropic electrical steel sheet of the present embodiment, in addition to optimally controlling the surface properties of the silicon steel sheet in the sheet width direction (C direction), the surface properties of the silicon steel sheet in the rolling direction (L direction) are also optimally controlled.

[0131] For example, when inside the transformer, the magnetization direction corresponds to the easy magnetization direction of the anisotropic electrical steel sheet, the magnetic loss can be reduced. However, for example, since in a 3-phase laminated core transformer, the magnetization directions in the T-shaped core are orthogonal to each other, even if an anisotropic electrical steel sheet having excellent magnetic properties in only one direction is used, the magnetic loss cannot be reduced as expected. . Therefore, in particular, in the T-shaped portion of the core, it is necessary to improve the magnetic properties of the silicon steel sheet in the width direction of the sheet in addition to the rolling direction, which is the easy magnetization direction of the silicon steel sheet.

[0132] Therefore, in the anisotropic electrical steel sheet of the present embodiment, in addition to the sheet width direction (C direction) of the silicon steel sheet, surface properties are controlled in the wavelength range of 20-100 µm also in the rolling direction (L direction) of the sheet. silicon steel.

[0133] More specifically, when the maximum amplitude value in the wavelength range of 20-100 μm among the frequency components obtained by performing Fourier analysis on the measured section curve parallel to the width direction of the silicon steel sheet is denoted as max-AMP _C100 , and the maximum amplitude value in the wavelength range of 20-100 μm, among the frequency components obtained by performing Fourier analysis on the measured cross-sectional curve parallel to the rolling direction of the silicon steel sheet, indicated as max-AMP _L100 , max-DIV ₁₀₀ , which is a value obtained by dividing max- AMP _C100 to max-AMP _L100 is controlled to be 1.5-6.0.

[0134] Meanwhile, in the present embodiment, like the first embodiment, it is mandatory to control ave-AMP _C100 which corresponds to the surface properties of the silicon steel sheet in the width direction of the sheet. Then, the surface properties in the rolling direction are also controlled. Therefore, the value of max-DIV ₁₀₀ increases as the value of max-AMP _L100 in the rolling direction decreases relative to the value of max-AMP _C100 in the width direction of the sheet. When max-DIV ₁₀₀ is 1.5 or more, it can be determined that the surface properties are sufficiently controlled not only in the sheet width direction but also in the rolling direction. The value of max-DIV ₁₀₀ is preferably 2.0 or more, and more preferably 3.0 or more.

[0135] On the other hand, the upper limit max-DIV ₁₀₀ is not specifically limited. However, it is not easy in the industry to control the surface properties in the rolling direction so that the surface properties of the silicon steel sheet in the width direction of the sheet are controlled, and then max-DIV ₁₀₀ is greater than 6.0. Therefore, max-DIV ₁₀₀ may be 6.0 or less.

[0136] In addition, when the maximum amplitude value in the wavelength range of 20-50 μm among the frequency components obtained by performing Fourier analysis on the measured section curve parallel to the width direction of the silicon steel sheet is denoted as max-AMP _C50 , and the maximum value amplitudes in the wavelength range of 20-50 μm among the frequency components obtained by performing Fourier analysis on the measured cross-sectional curve parallel to the rolling direction of the silicon steel sheet, indicated as max-AMP _L50 , max-DIV ₅₀ , which is the value obtained by dividing max -AMP _C50 to max-AMP _L50 is controlled so that it is 1.5-5.0.

[0137] To suitably control the surface properties in the rolling direction relative to the sheet width direction, max-DIV ₅₀ is preferably 2.0 or more, and more preferably 3.0 or more. On the other hand, the upper limit max-DIV ₅₀ is not specifically limited. However, it is not easy in the industry to control the surface properties in the rolling direction so that the surface properties of the silicon steel sheet in the width direction of the sheet are controlled and max-DIV ₅₀ is greater than 5.0. Therefore, max-DIV ₅₀ may be 5.0 or less.

[0138] FIG. 3 is a graph illustrating amplitude versus wavelength in Fourier analysis of the measured section curve parallel to the width direction of the sheet and the rolling direction of the silicon steel sheet (base steel sheet) with respect to the anisotropic electrical steel sheet according to the same embodiment. . In general, in a rolled steel sheet, it is more difficult to control the surface properties in the width direction of the sheet than in the rolling direction. In the first embodiment, the surface properties of the silicon steel sheet are controlled in the width direction of the sheet. However, in the present embodiment, the surface properties of the silicon steel sheet in the rolling direction in addition to the width direction of the sheet are also controlled. That is, as shown in FIG. 3, with respect to the wavelength range of 20-100 μm, the amplitude in the sheet width direction is optimized, and then the amplitude in the rolling direction is reduced.

[0139] For example, ave-AMP _C100 , max-AMP _C100 , max-AMP _L100 , ave-AMP _C50 , max-AMP _C50 and max-AMP _L50 can be measured using the following method in the same way as in the measurement method in the first embodiment.

[0140] When there is no coating on the silicon steel sheet, the surface properties of the silicon steel sheet can be evaluated directly, and when there is a coating on the silicon steel sheet, the surface properties of the silicon steel sheet can be evaluated after the coating is removed. For example, a coated anisotropic electrical steel sheet can be immersed in an alkaline solution at a high temperature. More specifically, immersion in an aqueous solution of sodium hydroxide containing NaOH: 20 mass% + H ₂ O: 80 mass% is carried out at 80°C for 20 minutes, and then water washing and drying are carried out, and thus the coating can be removed. (intermediate layer and insulating coating) on a silicon steel sheet. Meanwhile, the immersion time in the aqueous sodium hydroxide solution may vary according to the thickness of the coating on the silicon steel sheet.

[0141] With respect to the surface properties of the silicon steel sheet, in a contact type surface roughness measuring instrument, the tip radius of the contact needle is generally about a micron (µm), and the shape of the fine surface features cannot be determined. Therefore, it is preferable to use a non-contact type surface roughness measuring instrument. For example, a laser-type surface roughness tester (VK-9700, commercially available from Keyence Corporation) can be used.

[0142] First, the measured cross-sectional curves in the width direction of the sheet and in the rolling direction of the silicon steel sheet are obtained using a non-contact type surface roughness tester. When these measured section curves are obtained, the length of one measurement is 500 μm or more, and the total measurement length is 5 mm or more. The spatial resolution in the measurement direction (width direction of the silicon steel sheet) is 0.2 µm or less. The measured section curves are subjected to Fourier analysis without applying a low-pass or high-pass filter to the measured section curves, that is, without cutting out a specific frequency component from the measured section curves.

[0143] Among the frequency components obtained by performing the Fourier analysis on the measured cross-sectional curve, the average value and the maximum value of the amplitudes in the wavelength range of 20-100 μm are obtained. The average value of the amplitudes in the sheet width direction is designated as ave-AMP _C100 , the maximum value of the amplitudes in the sheet width direction is designated as max-AMP _C100 , and the maximum amplitude value in the rolling direction is designated as max-AMP _L100 . Similarly, among the frequency components obtained by performing the Fourier analysis on the measured cross-sectional curve, the average value and the maximum value of the amplitudes in the wavelength range of 20-50 μm are obtained. The average amplitude value in the sheet width direction is denoted as ave-AMP _C50 , the maximum amplitude value in the sheet width direction is denoted as max-AMP _C50 , and the maximum amplitude value in the rolling direction is denoted as max-AMP _L50 . Meanwhile, the above measurement and analysis can be performed at five or more locations while changing the measurement locations, and their average value can be obtained.

[0144] In addition, max-DIV ₁₀₀ is obtained by dividing max-AMP _C100 by max-AMP _L100 obtained above. Similarly, max-DIV ₅₀ is obtained by dividing max-AMP _C50 by max-AMP _L50 obtained above.

[0145] In the present embodiment, ave-AMP _C100 is controlled and then max-DIV ₁₀₀ is controlled to improve magnetic loss performance. In addition, if necessary, ave-AMP _C50 is monitored and then max-DIV ₅₀ is monitored to suitably improve the magnetic loss characteristics. The method to control these ave-AMP _C100 and max-DIV ₁₀₀ values will be described below.

[0146] In addition, in the anisotropic electrical steel sheet of the present embodiment, configurations other than the above-described surface properties are not specifically limited as in the first embodiment, and their descriptions will be omitted here.

[0147] Next, the manufacturing method of the anisotropic electrical steel sheet of the present embodiment will be described.

[0148] Meanwhile, the manufacturing method of the anisotropic electrical steel sheet of the present embodiment is not limited to the following method. The following manufacturing method is one example of manufacturing the anisotropic electrical steel sheet of the present embodiment.

[0149] For example, a method for manufacturing an anisotropic electrical steel sheet includes a casting process, a heating process, a hot rolling process, a hot strip state annealing process, a hot strip pickling process, a cold rolling process, a decarburization annealing process, a nitriding process, an annealing separator coating process, finishing annealing process, surface treatment process, intermediate layer forming process, insulation coating forming process, and magnetic domain driving process. However, since the casting process, the heating process, the hot rolling process, the hot strip state annealing process, the hot strip pickling process, the nitriding process, the annealing separator application process, the final annealing process, the intermediate layer formation process, the insulation coating formation process, and the magnetic domains are the same as in the first embodiment, their descriptions will be omitted here.

cold rolling process

[0150] In the cold rolling process of the present embodiment, as in the first embodiment, the reduction ratio in finishing cold rolling during cold rolling (cumulative reduction ratio in cold rolling without intermediate annealing or cumulative reduction ratio in cold rolling after intermediate annealing is carried out ) is preferably 80% or more, and more preferably 90% or more. In addition, the reduction ratio in finishing cold rolling during cold rolling is preferably 95% or less.

[0151] In the present embodiment, from the properties of the surface of the roll in the last pass (finishing stand) in cold rolling, the arithmetic mean Ra is 0.40 µm or less, and more preferably, the mean value of ave-AMP _C100 amplitudes in the wavelength range 20-100 µm among the frequency components obtained by performing the Fourier analysis is 0.050 µm or less, and the reduction in the last pass (finishing stand) in cold rolling is preferably 15% or more. When the rolling roll in the finishing pass is smoother and the reduction in the finishing pass is larger, it becomes easier to control the surface smoothness of the silicon steel sheet as a result. When the above cold rolling conditions are satisfied and the post-processing inspection conditions, ave-AMP _C100 , max-DIV ₁₀₀ , and the like, are satisfied. the silicon steel sheet can be suitably controlled.

Decarburizing Annealing Process

[0152] The same conditions as in the first embodiment can be used as the conditions of the oxidation state, holding temperature, and holding time of the decarburization annealing process of the present embodiment.

[0153] In addition, in the present embodiment, the above-described decarburization annealing conditions are controlled and the amount of oxygen on the surface of the decarburized and annealed sheet is controlled to be 0.95 g/m ² or less. For example, when the oxidation state is high in the above range, the holding temperature is lowered in the above range or the holding time is shortened in the above range, and the amount of oxygen on the surface of the steel sheet can be 0.95 g/m ² or less. In addition, for example, when the holding temperature is high in the above range, the oxidation state is lowered in the above range, or the holding time is shortened in the above range, and the amount of oxygen on the surface of the steel sheet may be 0.95 g/m ² or less. . Here, even if pickling is carried out using sulfuric acid, hydrochloric acid or the like after the decarburization annealing, it is not easy to control the amount of oxygen on the surface of the decarburized and annealed sheet to be 0.95 g/m ² or less. It is preferable to control the amount of oxygen on the surface of the decarburized and annealed sheet by controlling the decarburization annealing conditions described above.

[0154] The amount of oxygen on the surface of the decarburized and annealed sheet is preferably 0.75 g/m ² or less. When the amount of oxygen is smaller, it eventually becomes easier to control the surface smoothness of the silicon steel sheet. When the above conditions are satisfied in the decarburization annealing process and the control conditions in pre-processing and post-processing are satisfied, ave-AMP _C100 , max-DIV ₁₀₀ and the like. the silicon steel sheet can be suitably controlled.

Surface treatment process

[0155] In the present embodiment, with regard to the etching conditions for surface treatment, a solution containing a total amount of 0 to less than 10 mass% of one or two or more of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, chloric acid, an aqueous solution of chromium oxide, chromium sulfate, permanganate, peroxosulfuric acid and peroxophosphate. Using this solution, etching is carried out under conditions of high temperature and short time. More specifically, pickling is carried out when the temperature of the solution is set to 50-80°C and the immersion time is set to 1-30 seconds. When the pickling is carried out under such conditions, the excess of the annealing separator on the surface of the steel sheet can be efficiently removed, and the surface properties of the steel sheet can be suitably controlled. In the above range, when the acid concentration is lower, the liquid temperature is lower, and the immersion time is shorter, the formation of pickle pits on the surface of the steel sheet is limited, and as a result, it becomes easier to control the smoothness of the surface of the silicon steel sheet. When the above conditions are satisfied in the surface treatment process and the pretreatment control conditions, ave-AMP _C100 , max-DIV ₁₀₀ and the like are satisfied. the silicon steel sheet can be suitably controlled. Meanwhile, the conditions for washing with water in the surface treatment are not particularly limited, and washing can be carried out under known conditions.

[0156] In addition, in addition to the pickling and water washing treatment discussed above, the surface properties of the steel sheet can be controlled using a brush roll. For example, in the course of brushing, SiC is used as an abrasive material with an abrasive grain size of 100th to 500th, the brush roll reduction is 1.0mm to 5.0mm, and the rotation speed of the brush is 500- 1500 rpm In particular, when it is desired to control the surface properties of the silicon steel sheet in the width direction of the sheet, the brushing can be carried out so that the rotation axis is located in the rolling direction. On the other hand, when it is desired to control the surface properties of the silicon steel sheet in the rolling direction, the brushing can be carried out so that the rotation axis is located in the width direction of the sheet. To simultaneously control the surface properties in the sheet width direction and in the rolling direction, the brushing can be carried out so that the axis of rotation is located in both the sheet width direction and in the rolling direction. When brushing is carried out so that the rotation axis is located in the width direction of the sheet (the direction orthogonal to the rolling direction), the max-DIV ₁₀₀ of the silicon steel sheet can be appropriately controlled

[0157] When the above conditions are satisfied in the surface treatment process and the pretreatment control conditions are satisfied, ave-AMP _C100 , max-DIV ₁₀₀ and the like can be appropriately controlled. silicon steel sheet. Meanwhile, the conditions for washing with water in the surface treatment are not particularly limited, and washing can be carried out under known conditions.

[0158] In the present embodiment, it is possible to produce an anisotropic electrical steel sheet containing the silicon steel sheet obtained above as a base. More specifically, an anisotropic electrical steel sheet can be produced using a silicon steel sheet having an ave-AMP _C100 of 0.0001-0.050 µm and a max-DIV ₁₀₀ of 1.5-6.0 as a base. Preferably, an intermediate layer and an insulating coating can be formed on the surface of the silicon steel sheet, using the above silicon steel sheet as a base for manufacturing the anisotropic electrical steel sheet.

[0159] In the present embodiment, when the conditions of the above processes are controlled, the surface properties of the silicon steel sheet can be controlled. Since each of the conditions of these processes is a control condition for controlling the surface properties of the silicon steel sheet, it is not enough to satisfy only one condition. Unless these conditions are controlled simultaneously and all together, ave-AMP _C100 , max-DIV ₁₀₀ , etc. silicon steel sheet cannot be observed at the same time.

Example 1

[0160] Hereinafter, the effects of one aspect of the present invention will be described in more detail with reference to examples, but the conditions in the examples are one example of conditions used to confirm the feasibility and effects of the present invention, and the present invention is not limited to this one example of conditions. In the present invention, various conditions can be used without deviating from the gist of the present invention, and as long as the object of the present invention can be achieved.

[0161] Molten steel having adjusted steel components was cast to form a slab. The slab was heated at 1150°C, hot rolled to obtain a sheet with a thickness of 2.6 mm, hot strip annealed in two stages at 1120°C+900°C, quenched after hot strip annealing, pickled, cold rolled to obtain a sheet with a thickness of 0.23 mm, was decarburized and annealed, and nitrided and annealed so that the increment of nitrogen was 0.020%, and an annealing separator containing Al ₂ O ₃ and MgO was applied, final annealing was carried out, and then surface treatment was carried out by etching and washing with water.

[0162] As manufacturing conditions, the detailed conditions of the cold rolling process, the decarburization annealing process, the final annealing process, and the surface treatment process are shown in Tables 1-3. In the cold rolling process, with regard to the finishing pass (finishing stand) of the cold rolling, the reduction and roll roughness Ra were changed. In the process of decarburization annealing, the oxidation state (PH ₂ O/PH ₂ ) of the atmosphere, the holding temperature and the holding time were changed, and the amount of oxygen on the surface of the decarburized and annealed sheet was controlled. Meanwhile, in test No. 20, the oxidation state of the atmosphere was 0.15, but the holding temperature was 880°C and the holding time was 550 seconds, and therefore the amount of oxygen on the surface of the decarburized and annealed sheet could not be controlled to be 1 g/ ^m2 or less. In Test No. 17, pickling was carried out using sulfuric acid immediately after the decarburization annealing process, but the amount of oxygen on the surface of the decarburized and annealed sheet could not be controlled to be 1 g/m ² or less.

[0163] In addition, an atmosphere containing 50 vol% or more of hydrogen was used in the final annealing process, and the holding time was changed in accordance with the holding temperature. During the surface treatment, the acid concentration, the liquid temperature, and the immersion time during the pickling treatment were changed. Meanwhile, in Test No. 23, only washing with water was carried out without carrying out an etching treatment.

[0164] As manufacturing results, the chemical components of the silicon steel sheets and the surface properties of the silicon steel sheets are shown in Tables 4-9. Meanwhile, the chemical components and surface properties of the silicon steel sheets were determined based on the above method.

[0165] In the tables, "-" in the chemical composition of the silicon steel sheet indicates that the alloying element was not intentionally added or that its content is below the lower limit detected by the measurement. In the tables, underlined values indicate that they are outside the scope of the present invention. In this case, all silicon steel sheets did not have a forsterite coating and had a texture developed in the {110}<001> orientation.

[0166] Using the obtained silicon steel sheet as a base, an intermediate layer was formed on the surface of the silicon steel sheet and an insulating coating was formed, and magnetic domain control was performed to obtain an anisotropic electrical steel sheet, and magnetic loss characteristics were evaluated. Meanwhile, the intermediate layer was formed by performing heat treatment in an atmosphere having an oxidation state of (PH ₂ O/PH ₂ ) 0.0012 at 850° C. for 30 seconds. These intermediate layers mainly contained silicon oxide and had an average thickness of 25 nm.

[0167] In addition, in Tests Nos. 1-10 and Tests Nos. 21-30, a phosphoric acid-based coating was formed as an insulating coating. The phosphoric acid coating was formed by applying a phosphoric acid coating composition containing a mixture of colloidal silica, an aluminum phosphate salt or a magnesium phosphate salt and water, and performing a heat treatment under normal conditions. These phosphoric acid coatings mainly contained phosphorus-silica complex oxide and had an average thickness of 2 µm.

[0168] In addition, in Tests Nos. 11-20 and Tests Nos. 31-42, an aluminum borate-based coating was formed as an insulating coating. The aluminum borate coating was formed by applying an aluminum borate coating composition containing an alumosol and boric acid, and performing heat treatment under normal conditions. These aluminum borate coatings mainly contained aluminum boron oxide and had an average thickness of 2 µm.

[0169] In addition, on all anisotropic electrical steel sheets, after forming the insulating coating, laser beam irradiation was performed and non-destructive stress strain was applied to refine the magnetic domains.

[0170] Magnetic loss was evaluated using a single sheet tester (SST). From the obtained sheet of anisotropic electrical steel, a sample with a width of 60 mm and a length of 300 mm was taken so that the long side of the test sample was located in the direction of rolling, and W17/50 was measured (specific magnetic loss during magnetization of the steel sheet with a magnetic field induction of 1.7 T at 50 Hz). When W17/50 was 0.68 W/kg or less, the magnetic loss was determined to be favorable.

[0171] As shown in Tables 1 to 9, since the surface properties of the silicon steel sheets were appropriately controlled in the examples of the invention, the magnetic loss characteristics of the anisotropic electrical steel sheets were excellent. On the other hand, since the surface properties of the silicon steel sheets were not suitably controlled in the Comparative Examples, the magnetic loss characteristics of the anisotropic electrical steel sheets were not satisfied. Here, although not shown in the tables, for example, in Test No. 5, in the width direction of the silicon steel sheet, the surface roughness Ra was 0.4 µm or less when the threshold wavelength hp was 800 µm, and the surface roughness Ra was 0.2 µm or less when the threshold wavelength lc was 20 µm, but ave-AMP _C100 was greater than 0.050 µm. In addition, in Test No. 39 and Test No. 40, in the width direction of the silicon steel sheet, the surface roughness Ra was also 0.03 µm when the threshold wavelength lc was 250 µm, but in Test No. 39 ave-AMP _C100 was 0.020 µm or less, and in test No. 40 ave-AMP _C100 was greater than 0.020 µm.

[0172] [Table 1]

Manufacturing conditions cold rolling process Decarburizing Annealing Process Final annealing process Surface treatment process Degree of compression at the last pass, % Roughness of the roll during the last pass Ra, µm Atmospheric oxidation state The amount of oxygen on the surface, g / m ² Holding temperature, °C Holding time, hours Treatment solution type The concentration of the solution for processing, wt.% Processing solution temperature, °C Dive time, sec Test 1 5 0.5 0.25 1.36 1100 fifteen Sulphuric acid thirty 90 90 Test 2 5 0.5 0.15 0.98 1200 ten Sulphuric acid 25 90 60 Test 3 5 0.5 0.15 0.98 1200 twenty Sulphuric acid twenty 90 60 Test 4 5 0.4 0.15 0.98 1200 twenty Sulphuric acid twenty 90 60 Test 5 5 0.4 0.15 0.98 1200 twenty Sulphuric acid ten 80 thirty Test 6 ten 0.4 0.10 0.92 1200 twenty Sulphuric acid 3 80 thirty Test 7 twenty 0.1 0.10 0.92 1200 twenty Sulphuric acid 0.50 70 fifteen Test 8 twenty 0.1 0.10 0.92 1200 twenty Sulphuric acid 5 70 fifteen Test 9 thirty 0.0025 0.09 0.88 1150 thirty Sulphuric acid 0.50 70 thirty Test 10 thirty 0.1 0.09 0.88 1250 ten Sulphuric acid 0.50 70 fifteen Test 11 twenty 0.1 0.09 0.88 1200 twenty Hydrochloric acid 5 70 fifteen Test 12 twenty 0.1 0.09 0.88 1200 twenty Hydrochloric acid 5 60 fifteen Test 13 twenty 0.1 0.09 0.88 1200 twenty Hydrochloric acid 0.50 70 fifteen Test 14 twenty 0.1 0.09 0.88 1200 twenty Sulfuric acid + phosphoric acid 3+1 70 fifteen

[0173] [Table 2]

Manufacturing conditions cold rolling process Decarburizing Annealing Process Final annealing process Surface treatment process Degree of compression at the last pass, % Roughness of the roll during the last pass Ra, µm Atmospheric oxidation state The amount of oxygen on the surface, g / m ² Holding temperature, °C Holding time, hours Treatment solution type The concentration of the solution for processing, wt.% Processing solution liquid temperature, °C Dive time, sec Test 15 twenty 0.1 0.09 0.88 1200 twenty Sulphuric acid 0.50 70 fifteen Test 16 5 0.5 0.10 0.92 1200 twenty Sulphuric acid 3 80 thirty Test 17 ten 0.4 0.17 1.07 1200 twenty Sulphuric acid 7.5 80 thirty Test 18 ten 0.4 0.10 0.92 1200 twenty Sulphuric acid 25 80 60 Test 19 ten 0.5 0.10 0.92 1200 twenty Sulphuric acid 7.5 80 thirty Test 20 ten 0.4 0.15 1.10 1200 twenty Sulphuric acid 7.5 80 thirty Test 21 ten 0.4 0.15 0.98 1100 twenty Sulphuric acid 7.5 80 thirty Test 22 ten 0.4 0.10 0.92 1200 5 Sulphuric acid 7.5 80 thirty Test 23 ten 0.4 0.10 0.92 1200 twenty Not applicable Not applicable Not applicable Not applicable Test 24 ten 0.4 0.15 0.98 1200 twenty Sulphuric acid 7.5 25 thirty Test 25 ten 0.4 0.10 0.92 1200 twenty Sulphuric acid 25 fifty thirty Test 26 twenty 0.1 0.09 0.89 1200 twenty Sulphuric acid 0.50 60 thirty Test 27 twenty 0.1 0.09 0.90 1200 twenty Sulphuric acid 0.50 60 thirty Test 28 twenty 0.1 0.09 0.88 1200 twenty Sulphuric acid 0.50 60 thirty

[0174] [Table 3]

Manufacturing conditions cold rolling process Decarburizing Annealing Process Final annealing process Surface treatment process Degree of compression at the last pass, % Roughness of the roll during the last pass Ra, µm Atmospheric oxidation state The amount of oxygen on the surface, g / m ² Holding temperature, °C Holding time, hours Treatment solution type The concentration of the solution for processing, wt.% Processing solution liquid temperature, °C Dive time, sec Test 29 twenty 0.1 0.09 0.89 1200 twenty Sulphuric acid 0.50 60 thirty Test 30 twenty 0.1 0.09 0.87 1200 twenty Sulphuric acid 0.50 60 thirty Test 31 twenty 0.1 0.09 0.87 1200 twenty Sulphuric acid 0.50 60 thirty Test 32 twenty 0.1 0.09 0.89 1200 twenty Sulphuric acid 0.50 60 thirty Test 33 twenty 0.1 0.09 0.88 1200 twenty Sulphuric acid 0.50 60 thirty Test 34 twenty 0.1 0.09 0.89 1200 twenty Sulphuric acid 0.50 60 thirty Test 35 twenty 0.1 0.09 0.88 1200 twenty Sulphuric acid 0.50 60 thirty Test 36 twenty 0.1 0.09 0.87 1200 twenty Sulphuric acid 0.50 60 thirty Test 37 twenty 0.1 0.09 0.88 1200 twenty Sulphuric acid 0.50 60 thirty Test 38 twenty 0.1 0.09 0.90 1200 twenty Sulphuric acid 0.50 60 thirty Test 39 thirty 0.1 0.02 0.30 1250 thirty Sulphuric acid 0.30 70 fifteen Test 40 25 0.1 0.01 0.35 1250 thirty Sulphuric acid 0.30 60 fifteen Test 41 eight 0.4 0.10 0.92 1150 thirty Sulphuric acid 3 70 fifteen Test 42 ten 0.4 0.10 0.92 1150 thirty Sulphuric acid ten 70 fifteen

[0175] [Table 4]

Manufacturing results Component composition of silicon steel sheet (unit: wt%, the rest is Fe and impurities) Si Mn Cr Cu P sn Sb Ni B V Nb Mo Ti Bi Al C N S Se Test 1 3.2 - - - - - - - - - - - - - 0.001 0.0004 0.0022 0.0027 - Test 2 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0012 0.0025 - Test 3 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0010 0.0014 - Test 4 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0011 0.0014 - Test 5 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0010 0.0014 - Test 6 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0009 0.0014 - Test 7 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0010 0.0014 - Test 8 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0013 - Test 9 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0013 0.0025 - Test 10 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0004 0.0012 - Test 11 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0009 0.0014 - Test 12 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0010 0.0013 - Test 13 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0009 0.0014 - Test 14 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0008 0.0014 -

[0176] [Table 5]

Manufacturing results Component composition of silicon steel sheet (unit: wt%, the rest is Fe and impurities) Si Mn Cr Cu P sn Sb Ni B V Nb Mo Ti Bi Al C N S Se Test 15 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0010 0.0014 - Test 16 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0009 0.0013 - Test 17 3.2 - - - - - - - - - - - - - 0.001 0.0007 0.0010 0.0014 - Test 18 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0010 0.0014 - Test 19 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0013 - Test 20 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0013 - Test 21 3.2 - - - - - - - - - - - - - 0.001 0.0007 0.0006 0.0013 - Test 22 3.2 - - - - - - - - - - - - - 0.001 0.0007 0.0007 0.0014 - Test 23 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0014 - Test 24 3.2 - - - - - - - - - - - - - 0.001 0.0009 0.0005 0.0014 - Test 25 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0013 - Test 26 3.3 0.1 - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0014 - Test 27 3.3 - 0.1 - - - - - - - - - - - 0.001 0.0009 0.0011 0.0007 0.0017 Test 28 3.3 - - 0.1 - - - - - - - - - - 0.001 0.0012 0.0010 0.0014 -

[0177] [Table 6]

Manufacturing results Component composition of silicon steel sheet (units: wt%, the rest is Fe and impurities) Si Mn Cr Cu P sn Sb Ni B V Nb Mo Ti Bi Al C N S Se Test 29 3.3 - - - 0.01 - - - - - - - - - 0.001 0.0008 0.0006 0.0014 - Test 30 3.3 - - - - 0.05 - - - - - - - - 0.001 0.0008 0.0011 0.0006 0.0017 Test 31 3.3 - - - - - 0.03 - - - - - - - 0.001 0.0009 0.0009 0.0014 - Test 32 3.3 - - - - - - 0.05 - - - - - - 0.001 0.0013 0.0010 0.0009 0.0016 Test 33 3.3 - - - - - - - 0.002 - - - - - 0.001 0.0013 0.0011 0.0008 0.0015 Test 34 3.3 - - - - - - - - 0.02 - - - - 0.002 0.0014 0.0010 0.0014 - Test 35 3.3 - - - - - - - - - 0.03 - - - 0.001 0.0013 0.0009 0.0013 - Test 36 3.3 - - - - - - - - - - 0.02 - - 0.001 0.0008 0.0006 0.0014 - Test 37 3.3 - - - - - - - - - - - 0.005 - 0.001 0.0014 0.0009 0.0014 - Test 38 3.3 - - - - - - - - - - - - 0.003 0.001 0.0013 0.0010 0.0008 0.0016 Test 39 3.2 - - - - - - - - - - - - - 0.001 0.0017 0.0003 0.0008 - Test 40 3.2 - - - - - - - - - - - - - 0.001 0.0020 0.0004 0.0012 - Test 41 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0013 0.0014 - Test 42 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0012 0.0014 -

[0178] [Table 7]

Manufacturing results Assessment results Note Surface properties of silicon steel sheet Magnetic losses W _17/50 , W/kg ave-AMP _C100 , µm ave-AMP _C50 , µm Test 1 0.247 0.234 0.79 Comparative Example Test 2 0.137 0.130 0.74 Comparative Example Test 3 0.060 0.044 0.72 Comparative Example Test 4 0.059 0.043 0.71 Comparative Example Test 5 0.052 0.038 0.70 Comparative Example Test 6 0.049 0.036 0.68 Example according to the invention Test 7 0.025 0.017 0.63 Example according to the invention Test 8 0.033 0.024 0.66 Example according to the invention Test 9 0.029 0.020 0.65 Example according to the invention Test 10 0.023 0.016 0.62 Example according to the invention Test 11 0.034 0.023 0.67 Example according to the invention Test 12 0.028 0.019 0.63 Example according to the invention Test 13 0.026 0.018 0.63 Example according to the invention Test 14 0.031 0.021 0.67 Example according to the invention

[0179] [Table 8]

Manufacturing results Assessment results Note Surface properties of silicon steel sheet Magnetic losses W _17/50 , W/kg ave-AMP _C100 , µm ave-AMP _C50 , µm Test 15 0.026 0.018 0.63 Example according to the invention Test 16 0.061 0.045 0.72 Comparative Example Test 17 0.184 0.134 0.77 Comparative Example Test 18 0.098 0.072 0.73 Comparative Example Test 19 0.066 0.048 0.71 Comparative Example Test 20 0.178 0.130 0.78 Comparative Example Test 21 0.053 0.039 0.71 Comparative Example Test 22 0.054 0.040 0.72 Comparative Example Test 23 0.121 0.088 0.82 Comparative Example Test 24 0.092 0.067 0.72 Comparative Example Test 25 0.089 0.065 0.71 Comparative Example Test 26 0.026 0.017 0.63 Example according to the invention Test 27 0.025 0.017 0.63 Example according to the invention Test 28 0.025 0.016 0.63 Example according to the invention

[0180] [Table 9]

Manufacturing results Assessment results Note Surface properties of silicon steel sheet Magnetic losses W _17/50 , W/kg ave-AMP _C100 , µm ave-AMP _C50 , µm Test 29 0.026 0.018 0.64 Example according to the invention Test 30 0.023 0.016 0.62 Example according to the invention Test 31 0.024 0.016 0.62 Example according to the invention Test 32 0.026 0.018 0.63 Example according to the invention Test 33 0.025 0.017 0.62 Example according to the invention Test 34 0.026 0.018 0.64 Example according to the invention Test 35 0.027 0.019 0.63 Example according to the invention Test 36 0.025 0.017 0.63 Example according to the invention Test 37 0.024 0.016 0.63 Example according to the invention Test 38 0.025 0.017 0.62 Example according to the invention Test 39 0.018 0.012 0.60 Example according to the invention Test 40 0.021 0.014 0.61 Example according to the invention Test 41 0.051 0.037 0.71 Comparative Example Test 42 0.048 0.035 0.68 Example according to the invention

Example 2

[0181] Molten steel containing adjusted steel components was cast to form a slab. The slab was heated at 1150°C, hot rolled to obtain a sheet with a thickness of 2.6 mm, hot strip annealed in two stages at 1120°C+900°C, quenched after hot strip annealing, pickled, cold rolled to obtain a sheet with a thickness of 0.23 mm, was decarburized and annealed, and nitrided and annealed so that the increment of nitrogen was 0.020%, and an annealing separator containing Al ₂ O ₃ and MgO was applied, final annealing was carried out, and then a surface treatment was carried out with the implementation at least one of pickling, water washing and brushing.

[0182] As manufacturing conditions, the detailed conditions of the cold rolling process, the decarburization annealing process, the final annealing process, and the surface treatment process are shown in Tables 10-13. In the process of cold rolling, relative to the finishing pass (finishing stand) of cold rolling, the reduction and roughness of the roll Ra were changed. In the process of decarburization annealing, the oxidation state (PH ₂ O/PH ₂ ) of the atmosphere, the holding temperature and the holding time were changed, and the amount of oxygen on the surface of the decarburized and annealed sheet was controlled. Meanwhile, in Test No. 2-22, etching was carried out using sulfuric acid immediately after the decarburization annealing process, but the amount of oxygen on the surface of the decarburized and annealed sheet could not be controlled to be 1 g/m ² or less.

[0183] In addition, an atmosphere containing 50 vol% or more of hydrogen was used in the final annealing process, and the holding time was changed in accordance with the holding temperature. During the surface treatment, the acid concentration, the liquid temperature, and the immersion time during the pickling treatment were changed. Meanwhile, in test No. 2-43, washing with water and brushing were carried out without carrying out the pickling treatment.

[0184] As manufacturing results, the chemical components of the silicon steel sheets and the surface properties of the silicon steel sheets are shown in Tables 14-21. Meanwhile, the chemical components and surface properties of the silicon steel sheets were determined based on the above method.

[0185] In the Tables, "-" in the chemical composition of the silicon steel sheet indicates that the alloying element was not intentionally added or that its content is below the lower limit detected by the measurement. In the tables, underlined values indicate that they are outside the scope of the present invention. At the same time, all silicon steel sheets did not have a forsterite coating and had a texture developed in the {110}<001> orientation.

[0186] Using the obtained silicon steel sheet as a base, an intermediate layer was formed on the surface of the silicon steel sheet and an insulating coating was formed, and magnetic domain control was performed to obtain an anisotropic electrical steel sheet, and magnetic loss characteristics were evaluated. Meanwhile, the intermediate layer was formed by performing heat treatment in an atmosphere having an oxidation state of (PH ₂ O/PH ₂ ) 0.0012 at 850° C. for 30 seconds. These intermediate layers mainly contained silicon oxide and had an average thickness of 25 nm.

[0187] In addition, in Tests Nos. 2-1 to 2-15 and Tests Nos. 2-31 to 2-40, a phosphoric acid-based coating was formed as an insulating coating. The phosphoric acid coating was formed by applying a phosphoric acid coating composition containing a mixture of colloidal silica, an aluminum phosphate salt or a magnesium phosphate salt and water, and performing a heat treatment under normal conditions. These phosphoric acid coatings mainly contained phosphorus-silica complex oxide and had an average thickness of 2 µm.

[0188] In addition, in Tests Nos. 2-16 to 2-30 and Tests Nos. 2-41 to 2-55, an aluminum borate-based coating was formed as an insulating coating. The aluminum borate coating was formed by applying an aluminum borate coating composition containing alumosol and boric acid, and performing heat treatment under normal conditions. These aluminum borate coatings contained mainly alumina-boron and had an average thickness of 2 µm.

[0189] In addition, on all anisotropic electrical steel sheets, after forming the insulating coating, laser beam irradiation was performed and non-destructive stress strain was applied to refine the magnetic domains.

[0190] Magnetic loss was evaluated using a single sheet tester (SST). From the obtained sheet of anisotropic electrical steel, a sample of 60 mm wide and 300 mm long was taken so that the long side of the sample for research was located in the direction of rolling and in the direction along the width of the sheet, W17 / 50 was measured (specific magnetic loss during magnetization of the steel sheet with magnetic field induction 1.7 T at 50 Hz) using the test specimen in the rolling direction, and measured W6/50 (specific magnetic loss when magnetizing the steel sheet with a magnetic field induction of 0.6 T at 50 Hz) using the test specimen in the direction of sheet width. When the magnetic loss W17/50 in the rolling direction was 0.68 W/kg or less and the magnetic loss W6/50 in the sheet width direction was 0.80 W/kg or less, the magnetic loss was determined to be favorable.

[0191] As shown in Tables 10-21, since the surface properties of the silicon steel sheets were appropriately controlled in the examples of the invention, the magnetic loss characteristics of the anisotropic electrical steel sheets were excellent. On the other hand, since the surface properties of the silicon steel sheets were not suitably controlled in the Comparative Examples, the magnetic loss characteristics of the anisotropic electrical steel sheets were not satisfied. Meanwhile, although not shown in the tables, for example, in Test No. 2-3, in the width direction of the silicon steel sheet, the surface roughness Ra was 0.4 µm or less when the threshold wavelength hp was 800 µm, and the roughness Ra was 0.2 µm or less when the threshold wavelength lc was 20 µm, but ave-AMP _C100 was greater than 0.050 µm. In addition, in Test No. 2-54 and Test No. 2-55, in the width direction of the silicon steel sheet, the surface roughness Ra was also 0.03 µm when the threshold wavelength hp was 250 µm, but in Test No. 2-54 ave-AMP _C100 was 0.020 µm or less, and in Test No. 2-55, ave-AMP _C100 was greater than 0.020 µm.

[0192] [Table 10]

Manufacturing conditions cold rolling process Decarburizing Annealing Process Final annealing process Surface treatment process Degree of compression at the last pass, % Roughness of the roll during the last pass Ra, µm Atmospheric oxidation state The amount of oxygen on the surface, g / m ² Holding temperature, °C Holding time, hours Pickling processing Brushing treatment Treatment solution type The concentration of the treatment solution,
wt% Processing solution temperature, °C Dive time, sec Conducted (direction of rotation axis)
/ Not carried out Abrasive grain size Decrease in brushing, mm Brush rotation speed, rpm Test 2-1 5 0.5 0.15 0.98 1200 twenty Sulphuric acid twenty 90 60 Didn't carry out - - - Test 2-2 5 0.4 0.15 0.98 1200 twenty Sulphuric acid twenty 90 60 Didn't carry out - - - Test 2-3 5 0.4 0.15 0.98 1200 twenty Sulphuric acid ten 80 thirty Didn't carry out - - - Test 2-4 fifteen 0.4 0.10 0.92 1200 twenty Sulphuric acid 3 80 thirty Sheet width direction 500 3 750 Test 2-5 fifteen 0.4 0.10 0.92 1200 twenty Sulphuric acid 0.5 70 thirty Sheet width direction 500 3 750 Test 2-6 fifteen 0.1 0.12 0.95 1200 twenty Sulphuric acid 2 70 thirty Sheet width direction 500 3 750 Test 2-7 twenty 0.1 0.10 0.92 1200 twenty Sulphuric acid 0.5 70 fifteen Sheet width direction 500 3 750 Test 2-8 fifteen 0.1 0.12 0.95 1200 twenty Sulphuric acid 2 80 thirty Rolling direction 500 2 1000 Test 2-9 fifteen 0.1 0.12 0.95 1200 twenty Sulphuric acid 2 80 thirty Sheet width direction 500 2 500 Test 2-10 fifteen 0.1 0.12 0.95 1200 twenty Sulphuric acid 2 80 thirty Sheet width direction 500 four 1500 Test 2-11 fifteen 0.4 0.10 0.92 1200 twenty Sulphuric acid 0.5 60 thirty Rolling direction 500 four 1000 Test 2-12 fifteen 0.4 0.10 0.92 1200 twenty Sulphuric acid 0.5 60 thirty Sheet width direction 500 four 500 Test 2-13 fifteen 0.4 0.10 0.92 1200 twenty Sulphuric acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-14 thirty 0.1 0.09 0.88 1150 thirty Sulphuric acid 0.5 70 thirty Sheet width direction 500 3 750

[0193] [Table 11]

Manufacturing conditions cold rolling process Decarburizing Annealing Process Final annealing process Surface treatment process Degree of compression at the last pass, % Roughness of the roll during the last pass Ra, µm Atmospheric oxidation state The amount of oxygen on the surface, g / m ² Holding temperature, °C Holding time, hours Pickling processing Brushing treatment Treatment solution type The concentration of the treatment solution,
wt% Processing solution temperature, °C Dive time, sec Conducted (direction of rotation axis)
/ Not carried out Abrasive grain size Decrease in brushing, mm Brush rotation speed, rpm Test 2-15 thirty 0.1 0.09 0.88 1250 ten sulfuric
acid 0.5 70 fifteen Sheet width direction 500 3 750 Test 2-16 twenty 0.1 0.09 0.88 1200 twenty Hydrochloric acid 5 70 fifteen Sheet width direction 500 3 750 Test 2-17 twenty 0.1 0.09 0.88 1200 twenty Hydrochloric acid 5 60 fifteen Sheet width direction 500 3 750 Test 2-18 twenty 0.1 0.09 0.88 1200 twenty Hydrochloric acid 0.5 70 fifteen Sheet width direction 500 3 750 Test 2-19 twenty 0.1 0.09 0.88 1200 twenty Sulfuric acid + phosphoric acid 3+1 70 fifteen Sheet width direction 500 3 750 Test 2-20 twenty 0.1 0.09 0.88 1200 twenty Sulphuric acid 0.5 70 fifteen Sheet width direction 500 3 750 Test 2-21 5 0.5 0.10 0.92 1200 twenty Sulphuric acid 3 80 thirty Didn't carry out - - - Test 2-22 ten 0.4 0.17 1.07 1200 twenty Sulphuric acid 7.5 80 thirty Didn't carry out - - - Test 2-23 ten 0.4 0.10 0.92 1200 twenty Sulphuric acid 25 80 60 Didn't carry out - - - Test 2-24 twenty 0.1 0.09 0.89 1200 twenty Sulphuric acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-25 twenty 0.1 0.09 0.90 1200 twenty Sulphuric acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-26 twenty 0.1 0.09 0.88 1200 twenty Sulphuric acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-27 twenty 0.1 0.09 0.89 1200 twenty Sulphuric acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-28 twenty 0.1 0.09 0.87 1200 twenty Sulphuric acid 0.5 60 thirty Sheet width direction 500 3 750

[0194] [Table 12]

Manufacturing conditions cold rolling process Decarburizing Annealing Process Final annealing process Surface treatment process Degree of compression at the last pass, % Roughness of the roll during the last pass Ra, µm Atmospheric oxidation state The amount of oxygen on the surface, g / m ² holding temperature,
°C Holding time, hours Pickling processing Brushing treatment Treatment solution type The concentration of the treatment solution,
wt% Processing solution temperature, °C Dive time, sec Conducted (direction of rotation axis)
/ Not carried out Abrasive grain size Decrease in brushing, mm Brush rotation speed, rpm Test 2-29 twenty 0.1 0.09 0.87 1200 twenty sulfuric
acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-30 twenty 0.1 0.09 0.89 1200 twenty sulfuric
acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-31 twenty 0.1 0.09 0.88 1200 twenty sulfuric
acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-32 twenty 0.1 0.09 0.89 1200 twenty sulfuric
acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-33 twenty 0.1 0.09 0.88 1200 twenty sulfuric
acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-34 twenty 0.1 0.09 0.87 1200 twenty sulfuric
acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-35 twenty 0.1 0.09 0.88 1200 twenty sulfuric
acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-36 twenty 0.1 0.09 0.90 1200 twenty sulfuric
acid 0.5 60 thirty Sheet width direction 500 3 750 Test 2-37 fifteen 0.4 0.10 0.92 1200 twenty sulfuric
acid 3 80 thirty Didn't carry out - - - Test 2-38 fifteen 0.4 0.12 0.96 1200 twenty sulfuric
acid 2 80 thirty Sheet width direction 500 3 750 Test 2-39 fifteen 0.5 0.10 0.92 1200 twenty sulfuric
acid 7.5 80 thirty Sheet width direction 500 3 750 Test 2-40 fifteen 0.4 0.17 1.10 1100 twenty sulfuric
acid 7.5 80 thirty Sheet width direction 500 3 750 Test 2-41 fifteen 0.4 0.15 0.95 1100 twenty sulfuric
acid 7.5 80 thirty Sheet width direction 500 3 750 Test 2-42 fifteen 0.4 0.10 0.92 1200 5 sulfuric
acid 7.5 80 thirty Sheet width direction 500 3 750

[0195] [Table 13]

Manufacturing conditions cold rolling process Decarburizing Annealing Process Final annealing process Surface treatment process Degree of compression at the last pass, % Roughness of the roll during the last pass Ra, µm Atmospheric oxidation state The amount of oxygen on the surface, g / m ² Holding temperature, °C holding time,
hours Pickling processing Brushing treatment Treatment solution type The concentration of the treatment solution,
wt% Processing solution temperature, °C Dive time, sec Conducted (direction of rotation axis)
/ Not carried out Abrasive grain size Decrease in brushing, mm Brush rotation speed, rpm Test 2-43 fifteen 0.4 0.10 0.92 1200 twenty Not applicable Not applicable Not applicable Not applicable Sheet width direction 500 3 750 Test 2-44 fifteen 0.4 0.15 0.95 1200 twenty sulfuric
acid 7.5 25 fifteen Sheet width direction 500 3 750 Test 2-45 fifteen 0.4 0.10 0.92 1200 twenty sulfuric
acid 25 fifty thirty Sheet width direction 500 3 750 Test 2-46 ten 0.4 0.10 0.92 1150 thirty sulfuric
acid 3 70 fifteen Sheet width direction 500 3 750 Test 2-47 fifteen 0.4 0.10 0.92 1200 twenty sulfuric
acid 0.5 70 thirty Sheet width direction fifty 3 750 Test 2-48 fifteen 0.4 0.10 0.92 1200 twenty sulfuric
acid 0.5 70 thirty Sheet width direction 600 3 750 Test 2-49 fifteen 0.4 0.10 0.92 1200 twenty sulfuric
acid 0.5 70 thirty Sheet width direction 500 0.5 750 Test 2-50 fifteen 0.4 0.10 0.92 1200 twenty sulfuric
acid 0.5 70 thirty Sheet width direction 500 6 750 Test 2-51 fifteen 0.4 0.10 0.92 1200 twenty sulfuric
acid 0.5 70 thirty Sheet width direction 500 3 400 Test 2-52 fifteen 0.4 0.10 0.92 1200 twenty sulfuric
acid 0.5 70 thirty Sheet width direction 500 3 1800 Test 2-53 fifteen 0.4 0.10 0.92 1150 thirty sulfuric
acid 7.5 70 fifteen Sheet width direction 500 3 750 Test 2-54 thirty 0.1 0.02 0.30 1250 thirty sulfuric
acid 0.3 70 fifteen Sheet width direction 500 2 500 Test 2-55 25 0.1 0.01 0.35 1250 thirty Sulphuric acid 0.3 60 fifteen Sheet width direction 500 2 500

[0196] [Table 14]

Manufacturing results Component composition of silicon steel sheet (unit: wt%, the rest is Fe and impurities) Si Mn Cr Cu P sn Sb Ni B V Nb Mo Ti Bi Al C N S Se Test 2-1 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0011 0.0014 - Test 2-2 3.2 - - - - - - - - - - - - - 0.001 0.0009 0.0012 0.0012 - Test 2-3 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0009 0.0013 - Test 2-4 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0012 0.0014 - Test 2-5 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0010 0.0013 - Test 2-6 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0014 - Test 2-7 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0013 0.0013 - Test 2-8 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0009 0.0011 - Test 2-9 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0010 0.0014 - Test 2-10 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0009 0.0013 - Test 2-11 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0010 0.0012 - Test 2-12 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0010 0.0014 - Test 2-13 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0011 0.0013 - Test 2-14 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0012 0.0014 -

[0197] [Table 15]

Manufacturing results Component composition of silicon steel sheet (unit: wt%, the rest is Fe and impurities) Si Mn Cr Cu P sn Sb Ni B V Nb Mo Ti Bi Al C N S Se Test 2-15 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0008 0.0008 - Test 2-16 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0011 0.0012 - Test 2-17 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0012 0.0013 - Test 2-18 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0013 0.0012 - Test 2-19 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0012 0.0012 - Test 2-20 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0011 0.0011 - Test 2-21 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0012 0.0013 - Test 2-22 3.2 - - - - - - - - - - - - - 0.001 0.0006 0.0012 0.0012 - Test 2-23 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0011 0.0013 - Test 2-24 3.3 0.1 - - - - - - - - - - - - 0.001 0.0007 0.0006 0.0013 - Test 2-25 3.3 - 0.1 - - - - - - - - - - - 0.001 0.0009 0.0013 0.0008 0.0015 Test 2-26 3.3 - - 0.1 - - - - - - - - - - 0.001 0.0011 0.0010 0.0012 - Test 2-27 3.3 - - - 0.01 - - - - - - - - - 0.001 0.0007 0.0006 0.0014 - Test 2-28 3.3 - - - - 0.05 - - - - - - - - 0.001 0.0009 0.0011 0.0008 0.0016

[0198] [Table 16]

Manufacturing results Component composition of silicon steel sheet (units: wt%, the rest is Fe and impurities) Si Mn Cr Cu P sn Sb Ni B V Nb Mo Ti Bi Al C N S Se Test 2-29 3.3 - - - - - 0.03 - - - - - - - 0.001 0.0009 0.0010 0.0013 - Test 2-30 3.3 - - - - - - 0.05 - - - - - - 0.001 0.0013 0.0010 0.0009 0.0014 Test 2-31 3.3 - - - - - - - 0.002 - - - - - 0.001 0.0013 0.0011 0.0008 0.0015 Test 2-32 3.3 - - - - - - - - 0.02 - - - - 0.002 0.0014 0.0009 0.0014 - Test 2-33 3.3 - - - - - - - - - 0.03 - - - 0.001 0.0013 0.0010 0.0013 - Test 2-34 3.3 - - - - - - - - - - 0.02 - - 0.001 0.0007 0.0006 0.0012 - Test 2-35 3.3 - - - - - - - - - - - 0.005 - 0.001 0.0012 0.0011 0.0014 - Test 2-36 3.3 - - - - - - - - - - - - 0.003 0.001 0.0012 0.0010 0.0007 0.0017 Test 2-37 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0011 - Test 2-38 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0012 0.0012 - Test 2-39 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0011 0.0011 - Test 2-40 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0013 0.0014 - Test 2-41 3.2 - - - - - - - - - - - - - 0.001 0.0009 0.0014 0.0014 - Test 2-42 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0014 0.0014 -

[0199] [Table 17]

Manufacturing results Component composition of silicon steel sheet (unit: wt%, the rest is Fe and impurities) Si Mn Cr Cu P sn Sb Ni B V Nb Mo Ti Bi Al C N S Se Test 2-43 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0012 0.0012 - Test 2-44 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0011 0.0013 - Test 2-45 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0012 0.0011 - Test 2-46 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0013 0.0014 - Test 2-47 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0012 - Test 2-48 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0012 0.0011 - Test 2-49 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0013 0.0012 - Test 2-50 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0010 - Test 2-51 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0012 0.0011 - Test 2-52 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0012 0.0012 - Test 2-53 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0013 0.0013 - Test 2-54 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0008 0.0008 - Test 2-55 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0009 0.0007 -

[0200] [Table 18]

Manufacturing results Assessment results Note Surface properties of silicon steel sheet Magnetic losses in rolling direction W _17/50 , W/kg Magnetic losses in the direction along the width of the sheet W _6/50 , W/kg ave-AMP _C100 , µm ave-AMP _C50 , µm max DIV₁₀₀, micron max DIV_fifty, micron Test 2-1 0.060 0.044 1.2 1.1 0.72 0.95 Comparative Example Test 2-2 0.059 0.043 1.3 1.1 0.71 0.92 Comparative Example Test 2-3 0.052 0.038 1.4 1.3 0.70 0.90 Comparative Example Test 2-4 0.050 0.038 1.6 1.4 0.68 0.65 Example according to the invention Test 2-5 0.046 0.034 2.0 1.7 0.66 0.62 Example according to the invention Test 2-6 0.044 0.032 2.1 1.6 0.66 0.61 Example according to the invention Test 2-7 0.027 0.019 2.5 2.1 0.65 0.58 Example according to the invention Test 2-8 0.044 0.032 1.2 1.1 0.65 0.86 Example according to the invention Test 2-9 0.049 0.038 1.8 1.5 0.68 0.66 Example according to the invention Test 2-10 0.043 0.031 2.1 1.8 0.65 0.60 Example according to the invention Test 2-11 0.042 0.031 1.3 1.3 0.65 0.87 Example according to the invention Test 2-12 0.047 0.034 1.8 1.5 0.66 0.64 Example according to the invention Test 2-13 0.043 0.031 2.2 1.9 0.65 0.59 Example according to the invention Test 2-14 0.030 0.022 1.9 1.6 0.66 0.76 Example according to the invention

[0201] [Table 19]

Manufacturing results Assessment results Note Surface properties of silicon steel sheet Magnetic losses in rolling direction W _17/50 , W/kg Magnetic losses in the direction along the width of the sheet W _6/50 , W/kg ave-AMP _C100 , µm ave-AMP _C50 , µm max DIV₁₀₀, micron max DIV_fifty, micron Test 2-15 0.025 0.018 3.0 2.5 0.64 0.52 Example according to the invention Test 2-16 0.036 0.026 2.2 1.8 0.68 0.66 Example according to the invention Test 2-17 0.030 0.021 2.4 2.0 0.64 0.62 Example according to the invention Test 2-18 0.027 0.019 2.6 2.2 0.65 0.56 Example according to the invention Test 2-19 0.033 0.023 1.9 1.6 0.68 0.76 Example according to the invention Test 2-20 0.028 0.021 2.5 2.1 0.64 0.58 Example according to the invention Test 2-21 0.061 0.045 1.3 1.1 0.72 0.96 Comparative Example Test 2-22 0.184 0.134 1.1 0.9 0.77 0.99 Comparative Example Test 2-23 0.098 0.072 1.1 0.9 0.73 0.93 Comparative Example Test 2-24 0.028 0.020 2.4 2.0 0.64 0.60 Example according to the invention Test 2-25 0.027 0.019 2.7 2.4 0.65 0.54 Example according to the invention Test 2-26 0.026 0.018 2.1 1.8 0.64 0.69 Example according to the invention Test 2-27 0.027 0.020 2.3 1.9 0.65 0.63 Example according to the invention Test 2-28 0.025 0.018 3.0 2.5 0.64 0.48 Example according to the invention

[0202] [Table 20]

Manufacturing results Assessment results Note Surface properties of silicon steel sheet Magnetic losses in rolling direction W _17/50 , W/kg Magnetic losses in the direction along the width of the sheet W _6/50 , W/kg ave-AMP _C100 , µm ave-AMP _C50 , µm max DIV₁₀₀, micron max DIV_fifty, micron Test 2-29 0.025 0.019 2.4 2.1 0.63 0.60 Example according to the invention Test 2-30 0.027 0.020 2.7 2.3 0.65 0.54 Example according to the invention Test 2-31 0.026 0.019 2.5 2.0 0.63 0.58 Example according to the invention Test 2-32 0.028 0.021 2.3 1.9 0.64 0.63 Example according to the invention Test 2-33 0.029 0.022 2.4 1.9 0.65 0.60 Example according to the invention Test 2-34 0.026 0.020 2.6 2.2 0.64 0.56 Example according to the invention Test 2-35 0.026 0.019 2.3 1.9 0.65 0.63 Example according to the invention Test 2-36 0.027 0.020 2.7 2.4 0.63 0.54 Example according to the invention Test 2-37 0.045 0.029 1.2 1.1 0.66 0.87 Example according to the invention Test 2-38 0.048 0.037 1.4 1.3 0.68 0.83 Example according to the invention Test 2-39 0.067 0.049 1.4 1.3 0.72 0.81 Comparative Example Test 2-40 0.180 0.131 1.1 0.9 0.79 0.93 Comparative Example Test 2-41 0.053 0.040 1.4 1.3 0.71 0.83 Comparative Example Test 2-42 0.056 0.042 1.4 1.3 0.73 0.81 Comparative Example

[0203] [Table 21]

Manufacturing results Assessment results Note Surface properties of silicon steel sheet Magnetic losses in rolling direction W _17/50 , W/kg Magnetic losses in the direction along the width of the sheet W _6/50 , W/kg ave-AMP _C100 , µm ave-AMP _C50 , µm max DIV₁₀₀, micron max DIV_fifty, micron Test 2-43 0.122 0.038 1.3 1.0 0.84 0.86 Comparative Example Test 2-44 0.093 0.068 1.3 1.1 0.74 0.85 Comparative Example Test 2-45 0.090 0.066 1.4 1.3 0.73 0.82 Comparative Example Test 2-46 0.049 0.039 1.4 1.2 0.68 0.81 Example according to the invention Test 2-47 0.071 0.062 2.1 1.8 0.75 0.70 Comparative Example Test 2-48 0.046 0.034 1.3 1.2 0.68 0.83 Example according to the invention Test 2-49 0.044 0.030 1.4 1.3 0.66 0.81 Example according to the invention Test 2-50 0.068 0.059 2.2 1.7 0.73 0.71 Comparative Example Test 2-51 0.044 0.035 1.3 1.3 0.66 0.84 Example according to the invention Test 2-52 0.055 0.041 1.7 1.5 0.70 0.69 Comparative Example Test 2-53 0.049 0.036 2.1 1.8 0.68 0.70 Example according to the invention Test 2-54 0.019 0.013 2.5 2.1 0.60 0.67 Example according to the invention Test 2-55 0.022 0.015 2.4 2.2 0.61 0.68 Example according to the invention

Industrial Applicability

[0204] According to the above aspects of the present invention, when the surface properties of the base silicon steel sheet are optimally controlled, an anisotropic electrical steel sheet that exhibits excellent magnetic loss characteristics can be provided, and a manufacturing method thereof can be proposed. Therefore, the present invention has high industrial applicability.

Claims (54)

1. Anisotropic electrical steel sheet containing silicon steel sheet as the main steel sheet, wherein, when the average value of the amplitudes in the wavelength range of 20-100 μm among the frequency components obtained by performing the Fourier analysis on the measured section curve parallel to the width direction of the silicon steel sheet is denoted as ave-AMP _C100 , ave-AMP _C100 is 0, 0001-0.050 µm. 2. The anisotropic electrical steel sheet of claim 1, wherein ave-AMP _C100 is 0.0001-0.025 µm. 3. The anisotropic electrical steel sheet according to claim 1 or 2, wherein when the maximum value of the amplitudes in the wavelength range of 20-100 μm among the frequency components obtained by performing Fourier analysis on the measured section curve parallel to the width direction of the silicon steel sheet is indicated as max-AMP _C100 , and the maximum value of the amplitudes in the wavelength range of 20-100 μm among the frequency components obtained by performing Fourier analysis on the measured curve of the section parallel to the rolling direction of the silicon steel sheet, denoted as max-AMP _L100 , max-DIV ₁₀₀ , which is the value obtained by dividing max-AMP _C100 by max-AMP _L100 , is 1.5-6.0. 4. The anisotropic electrical steel sheet according to any one of claims 1 to 3, wherein the average value of the amplitudes in the wavelength range of 20-50 μm among the frequency components obtained by performing the Fourier analysis is indicated as ave-AMP _C50 , ave-AMP _C50 is 0.0001-0.035. 5. The anisotropic electrical steel sheet according to claim 4, wherein when the maximum value of the amplitudes in the wavelength range of 20-50 μm among the frequency components obtained by performing Fourier analysis on the measured section curve parallel to the width direction of the silicon steel sheet is denoted as max -AMP _C50 , and the maximum value of the amplitudes in the wavelength range of 20-50 μm among the frequency components obtained by performing Fourier analysis on the measured curve of the section parallel to the rolling direction of the silicon steel sheet, denoted as max-AMP _L50 , max-DIV ₅₀ , which is the value obtained by dividing max-AMP _C50 by max-AMP _L50 is 1.5-5.0. 6. The anisotropic electrical steel sheet according to claim 4 or 5, wherein ave-AMP _C50 is 0.0001-0.020 µm. 7. Sheet of anisotropic electrical steel according to any one of claims 1 to 6, wherein the silicon steel sheet contains as chemical components, wt.%: Si: 0.8% or more and 7.0% or less, Mn: 0 or more and 1.00% or less, Cr: 0 or more and 0.30% or less, Cu: 0 or more and 0.40% or less, P: 0 or more and 0.50% or less, Sn: 0 or more and 0.30% or less, Sb: 0 or more and 0.30% or less, Ni: 0 or more and 1.00% or less, B: 0 or more and 0.008% or less, V: 0 or more and 0.15% or less, Nb: 0 or more and 0.2% or less, Mo: 0 or more and 0.10% or less, Ti: 0 or more and 0.015% or less, Bi: 0 or more and 0.010% or less, Al: 0 or more and 0.005% or less, C: 0 or more and 0.005% or less, N: 0 or more and 0.005% or less, S: 0 or more and 0.005% or less and Se: 0 or more and 0.005% or less, and the rest is Fe and impurities. 8. The anisotropic electrical steel sheet according to any one of claims 1 to 7, wherein the silicon steel sheet has a texture developed in the {110}<001> orientation. 9. The anisotropic electrical steel sheet according to any one of claims 1 to 8, further comprising an interlayer in contact with the silicon steel sheet, the interlayer being a film of silicon oxide. 10. The anisotropic electrical steel sheet of claim 9, further comprising an insulating coating in contact with the intermediate layer, the insulating coating being a phosphoric acid based coating. 11. The anisotropic electrical steel sheet of claim 9, further comprising an insulating coating in contact with the intermediate layer, the insulating coating being an aluminum borate-based coating. 12. A method for manufacturing an anisotropic electrical steel sheet according to any one of claims 1 to 11, including: a hot rolling process of a slab heated to 1280° C. or lower to obtain a hot-rolled steel sheet; an annealing process of the hot-rolled steel sheet in a hot strip condition; a cold rolling process of the hot-rolled steel sheet after the hot strip state annealing process by cold rolling one or two or more times with intermediate annealing therebetween to obtain a cold-rolled steel sheet; a process for decarburizing annealing a cold-rolled steel sheet to obtain a decarburized and annealed sheet; nitriding process by nitriding annealing of decarburized and annealed sheet; a process for applying an annealing separator containing Al ₂ O ₃ and MgO to the surface of the decarburized and annealed sheet; a final annealing process of the decarburized and annealed sheet after applying the annealing separator to obtain a final annealed steel sheet; a surface treatment process for removing excess annealing separator from the surface of the final annealed steel sheet to obtain a silicon steel sheet; and manufacturing process of anisotropic electrical steel sheet using silicon steel sheet as a base, while in the process of cold rolling the reduction ratio in finishing cold rolling is 80% or more, the roughness Ra of the rolling roll in the last pass is 0.40 µm or less, and reduction in the last pass is 10% or more, while in the process of final annealing the oxidation state is 0.0001-0.2 when the annealing atmosphere contains hydrogen, or the dew point is 0°C or lower when the annealing atmosphere consists of an inert gas without hydrogen, as for the conditions of high-temperature soaking in an atmosphere containing 50 vol.% or more of hydrogen, the soaking temperature is 1100-1250°C, when the holding temperature is 1100-1150°C, the holding time is 30 hours or more, and when the holding temperature is higher than 1150-1250°C, the holding time is 10 hours or more, and while in the process of surface treatment use a solution containing a total amount of less than 20 wt.% of one or two or more of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, chloric acid, an aqueous solution of chromium oxide, chromium sulfate, permanganate, peroxosulfuric acid and peroxophosphate, set the temperature of the solution to 50-80°C, and set the dive time to 1-30 seconds.

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