GRAIN ORIENTED ELECTRIC STEEL SHEET

专利摘要:
oriented magnetic steel sheet. The present invention relates to an oriented magnetic steel sheet provided with a steel sheet having a steel sheet surface in which a groove is formed, the groove extending in a direction that crosses the rolling direction and the Groove depth direction matches the sheet thickness direction, where: the mean groove depth d is greater than 10 (mi) and not greater than 40 (mi); and when the groove is seen in a cross-section in the groove width direction orthogonal to the direction in which the groove extends, the deepest part of the groove deviates to the groove width direction side from the center of the groove width. groove, and the cross-sectional shape of the groove is asymmetric in the groove width direction with respect to the groove width center, wherein the groove width direction center is defined as the groove width center.
公开号:BR112017020753B1
申请号:R112017020753-2
申请日:2016-04-19
公开日:2021-08-10
发明作者:Tatsuhiko Sakai；Hideyuki Hamamura；Hisashi Mogi；Fumiaki Takahashi
申请人:Nippon Steel Corporation；
IPC主号:

专利说明:

[TECHNICAL FIELD OF THE INVENTION]
[001] The present invention refers to an electrical steel sheet with oriented grain. Priority is claimed under Japanese Patent Application No. 2015-086300 filed on Monday, April 20, 2015, the contents of which are incorporated by reference herein. [TECHNICAL BACKGROUND]
[002] In the related art, such as a steel sheet for an iron core of a transformer, an electrical steel sheet with oriented grain which exhibits excellent magnetic characteristics in a specific direction is known. Grain-oriented electrical steel sheet is a steel sheet in which a crystal orientation is controlled so that an easily magnetized geometric axis of a crystal grain and a rolling direction correspond to each other by a combination of a treatment. cold rolling and an annealing treatment. It is preferred that the iron loss of the grain-oriented electrical steel sheet is as small as possible.
[003] Iron loss is classified into an eddy current loss and a hysteresis loss. Furthermore, eddy current loss is classified into classic eddy current loss and anomalous eddy current loss. Typically, a grain-oriented electrical steel sheet is known in which an insulating film is formed on a surface of a steel sheet (base metal) whose crystal orientation is controlled as described above to reduce eddy current loss. classic. The insulating film also plays a role in applying electrical insulating properties, tensile strength, heat resistance, and the like to steel sheet. In addition, recently, a grain-oriented electrical steel sheet is also known in which a glass film is formed between the steel sheet and the insulating film.
[004] On the other hand, as a method to reduce anomalous eddy current loss, a magnetic domain control method of narrowing a width of a 180° magnetic domain (performing 180° magnetic domain enhancement) is known. forming a fatigue strain portion, which extends in a direction that intersects the rolling direction, at a predetermined interval along the rolling direction. In the fatigue strain formation method, a 180° magnetic domain refinement effect of a reflow magnetic domain, which occurs in the strain portion, is used. A representative method of this is a method of using a shock wave or rapid heating with laser irradiation. In this method, a surface shape of an irradiated portion hardly varies. On the other hand, in the groove forming method, a demagnetizing field effect due to a magnetic pole, which occurs in a groove sidewall, is used. In this case, it is known that when a cross-sectional shape of the slot is close to a rectangle, the magnetic domain control effect is high (Patent Document 4). That is, magnetic domain control is classified into a voltage application type and a groove forming type.
[005] In a case of manufacturing a wound core transformer using the electrical steel sheet with oriented grain, it is necessary to carry out a stress relief annealing treatment to remove a deformation stress that occurs when the electrical steel sheet with Oriented grain is spirally wound into a coil shape. In a case of fabricating a wound core using the grain-oriented electrical steel sheet which is subjected to magnetic domain control by the stress application method, the stress disappears due to the performance of the stress relief annealing treatment. Therefore, the magnetic domain refinement effect (ie, an anomalous eddy current loss reducing effect) is also lost.
[006] On the other hand, in a case of fabricating the wound core using the grain-oriented electrical steel sheet that is subjected to magnetic domain control by the groove forming method, the groove is not lost even when performing the stress relief annealing treatment. Consequently, it is possible to maintain the magnetic domain refinement effect. Consequently, in a method of manufacturing a magnetic domain control material for the wound core, the groove forming type is employed.
[007] Furthermore, in a case of fabricating a stacked core transformer, strain relief annealing is not performed. Consequently, it is possible to selectively employ any one of the tension application type and the grooving type.
[008] Furthermore, in a laser method that is a method representative of the type of application of tension, for example, as described in Patent Document 5, when irradiated with a laser with relatively high intensity, a plate surface The steel is slightly melted and a moderate depression with a depth of approximately 10 µm can be formed. However, in the moderate depression as described above, there is no occurrence of a magnetic pole with which the magnetic domain control effect is obtained. As a result, it is known that the magnetic domain control effect is lost after strain relief annealing.
[009] As the groove forming type magnetic domain control method, an electrolytic etching method is known in which a groove is formed in a steel plate surface of electrical steel plate with grain oriented by the etching method electrolytic (refer to Patent Document 1), a gear press method in which a groove is formed in a sheet steel surface by mechanically pressing a gear onto the sheet steel surface of the electric steel sheet with oriented grain (refer to the following Patent Document 2), and a method of laser irradiation in which a groove is formed in a steel sheet surface of electrical steel sheet with grain oriented (refer to the following Patent Document Patent 3).
[0010] In the electrolytic corrosion method, for example, an insulating film (or a glass film) on the surface of the steel sheet is removed in a linear fashion with a laser or mechanical means, and then the electrolytic attack is carried out on to a portion in which the steel sheet is exposed, thus forming a groove in the surface of the steel sheet. In a case of employing the electrolytic etching method, a grain-oriented electrical steel sheet manufacturing process becomes complicated. So there is a problem that the manufacturing cost increases. Furthermore, in the gear press method, since the steel sheet which is the grain-oriented electrical steel sheet is a very hard steel sheet containing 3% by weight of Si, abrasion and damage to the gear will likely occur. In a case of employing the gear press method, when the gear is abraded, the groove becomes shallow, and a difference in a groove depth occurs. Therefore, there is a problem that it is difficult to sufficiently obtain an anomalous eddy current loss reducing effect.
[0011] On the other hand, in a case of the irradiation method to be, direct work is performed. Consequently, a complicated process like chemical etching is not necessary. Furthermore, non-contact type work is carried out and thus the same gear abrasion as in press work and the like does not occur. As a result, it is possible to stably form a groove on the sheet steel surface. For example, the following Patent Document 4 discloses a technology for improving the magnetic domain refinement effect (iron loss reducing effect) by making a groove contour shape (groove cross-section shape) into a cross-section, which is perpendicular to a groove extension direction, close to a rectangle in the electrical steel sheet with grain oriented where the groove is formed in the steel sheet surface according to a laser irradiation method. [PRIOR TECHNICAL DOCUMENT] [PATENT DOCUMENT]
[0012] [Patent Document 1] Japanese Examined Patent Application, Second Publication No. S62-54873
[0013] [Patent Document 2] Japanese Examined Patent Application, Second Publication No. S62-53579
[0014] [Patent Document 3] Japanese Unexamined Patent Application, First Publication No. H6-57335
[0015] [Patent Document 4] Japanese Unexamined Patent Application, First Publication No. 2012-177164
[0016] [Patent Document 5] Japanese Unexamined Patent Application, First Publication No. 2007-2334 DESCRIPTION OF THE INVENTION [PROBLEMS TO BE SOLVED BY THE INVENTION]
[0017] As an index that indicates the performance of electrical steel sheet with oriented grain, there is a magnetic flux density (for example, a magnetic flux density B8 that occurs in a magnetic field of 800 A/m) in addition to the loss of iron described above. In grain-oriented electrical steel sheet, it is preferable that the iron loss is low and the magnetic flux density is high. However, when a groove is formed in the steel sheet surface, the magnetic flux density decreases. Particularly, as disclosed in Patent Document 4, as the groove cross-sectional shape approaches a rectangle, the volume of iron, which is removed from the steel sheet, increases. Therefore, there is a problem that a reduction in magnetic flux density becomes significant. In addition, when electrical steel sheet, in which a groove is formed using a high heat source such as a laser, is subjected to bending work when used on a wound iron core, there is a problem that the sheet is likely to steel is fractured from the groove as a starting point.
[0018] The invention was carried out in consideration of the problems described above, and an objective of the same is to make the maximization of a reducing effect of iron loss and the minimization of a reduction in a magnetic flux density to be compatible with one another. another with satisfactory balance in a grain-oriented electrical steel sheet where a groove is formed in a steel sheet surface for magnetic domain refinement. [WAYS TO SOLVE THE PROBLEM]
[0019] The foundation of the invention is as follows.
[0020] (1) According to one aspect of the invention, there is provided a grain-oriented electrical steel sheet that includes a steel sheet having a steel sheet surface in which a groove, extending in a crossing direction a rolling direction and whose groove depth direction corresponds to a sheet thickness direction, is formed. An average groove depth D is greater than 10 μm and equal to or less than 40 μm. In a case where the groove is seen in a cross-section in the groove width direction that is perpendicular to a groove extension direction, when a groove center in the groove width direction is defined as a width center of groove width, a deeper portion of the groove deviates from the center of the groove width toward one side in the direction of the groove width, and a cross-sectional shape of the groove is asymmetrical with respect to the center of the groove width as a reference. in the direction of the groove width. In a case where the groove is seen in cross-section in the groove width direction, the groove includes a first groove surface and a second groove surface as a pair of inclined surfaces that are inclined towards the deeper portion. of the groove of the sheet steel surface and the center of the groove width is situated on a second side of the groove surface when viewed from the deeper portion. When an angle, which is formed by a first straight line of groove end obtained by linearly approaching the first groove surface and the sheet thickness direction, is defined as a first angle θ1 and an angle, which is formed by a second groove end straight line obtained by linearly approaching the second groove surface and the sheet thickness direction, is defined as a second angle θ2, the first angle θ1 and the second angle θ2 satisfy the following Conditional Expressions (1) to (3).

[0021] (2) In electrical steel sheet with grain oriented according to (1), in steel sheet, a grain size of a crystal grain which is in contact with the groove, may be 5 µm or more.
[0022] (3) In electrical steel sheet with grain oriented according to (2), when the groove is seen in cross section in the groove width direction, a grain size of a crystal grain, which exists in a underside of the groove in the steel sheet in the sheet thickness direction, can be equal to or greater than 5 μm and equal to or less than the sheet thickness of the steel sheet.
[0023] (4) In electrical steel sheet with grain oriented according to any one of (1) to (3), when the groove is seen in a longitudinal groove cross-section, including the groove extension direction and the sheet thickness direction, an arithmetic mean height Ra of a roughness curve, which constitutes a contour of a lower groove region, can be from 1 µm to 3 µm and an average length of RSm of a roughness curve element, which constitutes the contour of the lower region of the groove, can be from 10 μm to 150 μm. [EFFECTS OF THE INVENTION]
[0024] According to the aspect of the invention, it is possible to make the maximization of the reducing effect of iron loss and the minimization of a reduction in the magnetic flux density to be compatible with each other with satisfactory balance in a plate grain-oriented electrical steel in which a groove is formed in a sheet steel surface for magnetic domain refinement. [BRIEF DESCRIPTION OF THE DRAWINGS]
[0025] Figure 1 is a plan view of an electric steel sheet with oriented grain 1 according to an embodiment of the invention.
[0026] Figure 2 is a cross-sectional view of an arrow taken along line A-A in Figure 1 (viewed when a slot 5 is observed in a cross-section that includes a slot-extension direction.
[0027] Figure 3 is a cross-sectional view of an arrow taken along line B-B in Figure 1 (seen when slot 5 is observed in a cross-section perpendicular to the slot extension direction.
[0028] Figure 4 is a first explanatory view regarding a method of specifying an average depth D of groove 5.
[0029] Figure 5A is a second explanatory view regarding the method of specifying the average depth D of groove 5.
[0030] Figure 5B is a third explanatory view regarding the method of specifying the average depth D of groove 5.
[0031] Figure 6 is a fourth explanatory view regarding the method of specifying the average depth D of groove 5.
[0032] Figure 7A is a first explanatory view relating to a method of specifying a groove contour 5 in a cross-section in the groove width direction.
[0033] Figure 7B is a second explanatory view regarding the method of specifying a groove contour 5 in the cross-section in the groove width direction.
[0034] Figure 8 is a third explanatory view relating to the method of specifying a groove contour 5 in cross-section in the groove width direction.
[0035] Figure 9 is a plan view that schematically illustrates a secondary recrystallized grain that exists in a steel plate 2.
[0036] Figure 10 is a first explanatory view relating to a method of specifying a groove bottom region 5d of groove 5 in a longitudinal groove cross-section.
[0037] Figure 11 is a second explanatory view relating to a method of specifying the groove bottom region 5d of groove 5 in the longitudinal groove cross section.
[0038] Figure 12 is a flowchart illustrating the manufacturing processes of electrical steel sheet with grain oriented 1.
[0039] Figure 13 is a first explanatory view regarding a process of laser radiation S08 in the manufacturing processes of electrical steel sheet with oriented grain 1.
[0040] Figure 14A is a second explanatory view referring to a laser radiation process S08 in the manufacturing processes of electrical steel sheet with oriented grain 1.
[0041] Figure 14B is a third explanatory view referring to a laser radiation process S08 in the manufacturing processes of electrical steel sheet with oriented grain 1.
[0042] Figure 14C is a fourth explanatory view referring to a process of laser radiation S08 in the manufacturing processes of electrical steel sheet with oriented grain 1.
[0043] Figure 15 is a fifth explanatory view regarding a process of laser radiation S08 in the manufacturing processes of electrical steel sheet with oriented grain 1. [MODALITIES OF THE INVENTION]
[0044] Later in this document, a preferred embodiment of the invention will be described in detail. However, the invention is not limited to the configurations disclosed in this embodiment, and various modifications can be made in a range that does not depart from the essence of the invention. In addition, the lower limit and the upper limit are also included in limiting ranges of numerical values that will be described later.
[0045] However, the lower limit is not included in a limiting range of numerical values that is described as "greater than" the lower limit, and the upper limit is not included in a limiting range of numerical values that is described as " less than" the upper limit.
[0046] Later in this document, an embodiment of the invention will be described in detail with reference to the accompanying drawings.
[0047] Figure 1 is a plan view of an electric steel sheet with oriented grain 1 according to this modality. Figure 2 is a cross-sectional view of an arrow taken along line AA in Figure 1. Figure 3 is a cross-sectional view of an arrow taken along line BB in Figure 1. Furthermore, in Figure 1 to Figure 3, a rolling direction of electric steel sheet with oriented grain 1 is set to X, a sheet width direction (direction perpendicular to the rolling direction in the same plane) of electric steel sheet with oriented grain 1 is set as Y, and a sheet thickness direction (direction perpendicular to an XY plane) of electrical steel sheet with oriented grain 1 is defined as Z.
[0048] As illustrated in Figures 1 to 3, the grain oriented electrical steel sheet 1 includes a steel sheet (base metal) 2 in which a crystal orientation is controlled by a combination of a cold rolling treatment and an annealing treatment so that an easily magnetized geometric axis of a crystal grain and the rolling direction X correspond to each other, a glass film 3 which is formed on a surface (steel plate surface 2a) of the steel sheet 2, and an insulating film 4 which is formed on a surface of the glass film 3.
[0049] As illustrated in Figure 1, a plurality of grooves 5, which extend in a direction that crosses the rolling direction X and in which a groove depth direction corresponds to the sheet thickness direction Z, is formed on the surface of sheet steel 2a along the rolling direction X at a predetermined interval for magnetic domain refinement. That is, Figure 2 is a view when one of the grooves 5 is seen in a cross-section that includes the groove extension direction and the sheet thickness direction Z. Figure 3 is a view when a groove 5 is observed in a cross section perpendicular to the groove extension direction. In addition, slots 5 can be provided to cross the X-roll direction, and it is not necessary for the slot-extension direction and the X-roll direction to cross. However, in this modality, a case where the groove extension direction and the X roll direction intersect will be exemplified for convenience of explanation. Furthermore, in a case where each of the grooves 5 is viewed from the sheet thickness direction Z (in a case of a plan view of the groove 5), the groove 5 may have an arc shape. However, in this embodiment, slot 5 having a linear shape is exemplified for convenience of explanation.
[0050] Steel sheet 2 contains, as chemical components in terms of mass fraction, Si: 0.8% to 7%, C: more than 0% and equal to or less than 0.085%, Acid-soluble Al: 0 % to 0.065% N: 0% to 0.012%, Mn: 0% to 1%, Cr: 0% to 0.3% Cu: 0% to 0.4%, P: 0% to 0.5% , from Sn: 0% to 0.3%, from Sb: 0% to 0.3% Ni: 0% to 1%, S: 0% to 0.015%, Se: 0% to 0.015%, and the rest including Fe and unavoidable impurities.
[0051] The chemical components of sheet steel 2 are chemical components that are preferable for a Goss texture control where a crystal orientation is integrated with a {110}<001> orientation. Among the elements, Si and C are basic elements, and acid-soluble Al, N, Mn, Cr, Cu, P, Sn, Sb, Ni, S and Se are selective elements. Selective elements may be contained in correspondence with their purpose. Consequently, it is not necessary to limit the lower limit, and the lower limit can be 0%. Furthermore, the effect of this modality does not deteriorate even when the selective elements are contained as impurities. In steel sheet 2, the rest of the basic elements and the selective elements can be composed of Fe and impurities. Furthermore, impurities represent elements that are inevitably mixed due to ore and scrap as a raw material, or a manufacturing environment and the like when industrially manufacturing steel sheet 2.
[0052] In addition, an electrical steel sheet is typically subjected to purification annealing during secondary recrystallization. Discharge of an inhibitor-forming element out of a system occurs in purification annealing. In particular, a reduction in one concentration occurs significantly with respect to N and S, and the concentration becomes 50 ppm or less. Under typical purification annealing conditions, the concentration becomes 9 ppm or less, or 6 ppm or less. If purification annealing is carried out sufficiently, the concentration reaches a certain point (1 ppm or less) at which detection is impossible in typical analysis.
[0053] The chemical component of steel sheet 2 can be measured according to a typical steel analysis method. For example, the chemical components of steel sheet 2 can be measured using inductively coupled plasma atomic emission spectrometry (ICP-AES). Specifically, it is possible to specify the chemical components by measuring a 35 mm square specimen, which is obtained from the center position of steel sheet 2 after film removal, using ICPS-8100 (a measuring device, produced by Shimadzu Corporation) and the like under conditions based on a calibration curve that is created in advance. In addition, C and S can be measured using a combustion infrared ray absorption method, and N can be measured using an inert gas fusion thermal conductivity method.
[0054] For example, the glass film 3 is constituted by a composite oxide such as forsterite (Mg2SiO4), spinel (MgAl2O4), and cordierite (Mg2Al4Si5O16). Although details are described later, the glass film 3 is a film which is formed to prevent adhesion to the steel sheet 2 in a final annealing process which is one of the grain oriented electric steel sheet manufacturing processes 1. Consequently , the glass film 3 is not an essential element among the constituent elements of the grain-oriented electric steel sheet 1.
[0055] For example, the insulating film contains colloidal silica and phosphate, and exerts a function of applying electrical insulating properties, a tensile strength, corrosion resistance, heat resistance, and similar to steel sheet 2.
[0056] In addition, for example, the glass film 3 and the insulating film 4 can be removed by the following method. The oriented grain electric steel sheet 1 including glass film 3 or the insulating film 4 is immersed in an aqueous solution of sodium hydroxide containing 10% by mass of NaOH and 90% by mass of H2O at 80° C for 15 minutes. Then, the oriented grain electric steel sheet 1 is immersed in an aqueous solution of sulfuric acid containing 10% by mass of H2SO4 and 90% by mass of H2O at 80°C for 3 minutes. Then, the oriented grain electric steel sheet 1 is immersed in an aqueous solution of nitric acid containing 10% by mass of HNO3 and 90% by mass of H2O at room temperature for a period of time which is slightly longer. short than 1 minute, and is washed away. Finally, the grain oriented electric steel sheet 1 is dried using a hot wind blower for a period of time which is slightly shorter than 1 minute. Furthermore, in a case where the glass film 3 or the insulating film 4 is removed from the grain-oriented electrical steel sheet 1 according to the method described above, it is confirmed that a shape or roughness of the groove 5 of the steel plate. steel 2 is approximately equal to one shape or roughness before forming glass film 3 or insulating film 4.
[0057] As illustrated in Figure 3, in this embodiment, in a case where the slot 5 is seen in a cross section (a cross section in the slot width direction or a cross slot cross section) that is perpendicular to a direction of groove extension (direction that is parallel to the sheet width direction Y in this modality), a depth from the steel sheet surface 2a to the deepest portion of the groove 5 is defined as a groove depth Da and the center of the groove 5 in a groove width direction (direction that is parallel to the lamination direction X in this mode) is set to a GC groove width center. As illustrated in Figure 3, in the grain oriented electric steel sheet 1 of this modality, the deeper portion of the groove 5 deviates from the center of groove width GC towards one side in the groove width direction, and a shape in The cross section of slot 5 is asymmetric with respect to the center of slot width GC as a reference in the slot width direction.
[0058] Furthermore, in a case where the groove 5 is seen in cross-section of the transverse groove, the groove 5 includes a first groove surface 5a and a second groove surface 5b as a pair of inclined surfaces that are inclined from the sheet steel surface 2a towards the deeper portion of the groove 5. When viewed from the deeper portion of the groove 5, the center of groove width GC is situated on one side of the second groove surface 5b. Furthermore, in a case where the groove 5 is seen in the transverse groove cross-section, an angle, which is formed by a first straight groove end line Lh1 obtained by linearly approaching the first groove surface 5a and the direction of sheet thickness Z, is defined as a first angle θ1, and an angle, which is formed by a second straight groove end line Lh2 obtained by linearly approximating the second groove surface 5b and the direction of sheet thickness Z, is defined as a second angle θ2.
[0059] In this mode, the average depth D of groove 5 is greater than 10 μm and equal to or less than 40 μm. In a case where the slot 5 is seen in the cross-slot cross section, the deeper portion of the slot 5 deviates from the slot width center GC towards one side in the slot width direction, and the shape in cross section The transverse slot 5 is asymmetric with respect to the slot width center GC as a reference in the slot width direction. In the following description, the characteristic relating to the average depth D of the groove 5 is called a depth condition, and the characteristic relating to the cross-sectional shape of the groove 5 is called a shape condition.
[0060] In a state where the slot width of slot 5, which satisfies the depth condition and the shape condition, is fixed at a constant value, the first angle θ1 always becomes an acute angle, regardless of a value. of the average depth D, and the second angle θ2 is always greater than the first angle θ1. Furthermore, in a state where the slot width of slot 5 is fixed at a constant value, the first angle θ1 decreases along with an increase in the average depth D, and the first angle θ1 increases along with a decrease in the average depth D .
[0061] When the average depth D increases, a volume of iron that is removed from the steel sheet 2 increases. Consequently, an amount of reduction of a magnetic flux density also increases. However, when the first angle θ1 decreases along with an increase in the average depth D, an antimagnetic field effect from a magnetic pole, which is shown on the side surface of slot 5, increases. Consequently, a magnetic domain refinement effect (reducing iron loss effect) also increases. On the other hand, when the average depth D decreases, a volume of iron that is removed from the steel sheet 2 decreases. Consequently, the amount of magnetic flux density reduction also decreases. However, when the first angle θ1 increases together with a reduction in the average depth D, the anti-magnetic field effect of the magnetic pole that is shown on the side surface of slot 5 decreases. Consequently, the reducing effect of iron loss also decreases.
[0062] As described above, when the average depth D of groove 5 is made to be large by prioritizing the maximization of the iron loss reducing effect, a reduction in the magnetic flux density becomes significant. On the other hand, when the average depth D of the groove 5 is made to be small by giving priority to minimizing a reduction in the magnetic flux density, it is difficult to obtain a sufficient iron loss reducing effect. From a result of the verification made by the present inventors, it is proven that it is important that the groove 5 satisfies the shape condition and the depth condition where the average depth D of the groove 5 is greater than 10 µm and equal to or less than 40 µm in order to make the maximization of the reducing effect of iron loss and the minimization of a reduction in the magnetic flux density to be compatible with each other with a satisfactory balance.
[0063] In a case where the average depth D is 10 µm or less (in a case where the average depth D is shallower than 10 µm), a volume of iron that is removed from the steel plate 2 decreases and, in this way, an amount of magnetic flux density reduction also decreases. However, since the first angle θ1 increases, the antimagnetic field effect of a magnetic pole that is shown on a side surface of the slot 5 decreases. As a result, in a case where the mean depth D is 10 µm or less, it is difficult to obtain a sufficient iron loss reducing effect. On the other hand, in a case where the average depth D is greater than 40 µm (in a case where the average depth D is greater than 40 µm), the first angle θ1 decreases. Consequently, the antimagnetic field effect of the magnetic pole which is shown on the side surface of the slot 5 increases. As a result, it is possible to obtain a great iron loss reducing effect. However, in a case where the average depth D is greater than 40 µm, a volume of iron that is removed from steel sheet 2 increases. Consequently, an amount of reduction of a magnetic flux density also increases.
[0064] As described above, in a case where the average depth D is 10 µm or less, and in a case where the average depth D is greater than 40 µm, it is difficult to make the maximization of the reducing effect of loss of iron and minimization of the reduction in magnetic flux density are compatible with each other. Consequently, in this mode, groove 5, which satisfies both the shape condition and the depth condition where the average depth D is greater than 10 μm and equal to or less than 40 μm, is provided in the steel sheet 2. with this, the maximization of the reducing effect of iron loss and the minimization of the reduction in the magnetic flux density become compatible with each other with a satisfactory balance.
[0065] In addition, in groove 5, when a region, which satisfies the depth condition and the shape condition, is defined as an asymmetrical groove region, and an existence rate of the asymmetrical groove region in the direction of extension of the slot is defined as α (= a total length of the asymmetric slot region in the direction of slot extension/a total length of slot 5), the greater the existence rate α of the asymmetric slot region in slot 5, the greater the suppression effect of the reduction in magnetic flux density. Consequently, it is preferable that the existence rate α of the asymmetric groove region be as high as possible. However, when the asymmetrical groove region exists at least in a partial section of groove 5, it is possible to obtain the effect described above. Consequently, the existence rate α of the asymmetric slot region can be greater than zero.
[0066] When the groove cross-sectional shape is defined as asymmetric, it is possible to make the maximization of the reducing effect of iron loss and the minimization of the reduction in magnetic flux density to be compatible with each other with satisfactory balance. That is, in a groove having an asymmetrical cross-sectional shape, a volume of iron that is removed from a steel sheet is additionally suppressed compared to a groove having a rectangular cross-sectional shape. As a result, it is possible to suppress a reduction in magnetic flux density. Furthermore, in the groove having the asymmetrical cross-sectional shape, when a shape, which is close to that of a side surface of a groove having a rectangular cross-sectional shape with a large iron loss reducing effect, remains partially, it is possible suppress a reduction in the iron loss effect.
[0067] Regarding the asymmetric shape of the slot 5, it is preferable that the first angle θ1 and the second angle θ2 satisfy the following Conditional Expressions (1) to (3). From a verification result made by the present inventors, when the groove 5 satisfies the depth condition and the shape condition, and the first angle θ1 and the second angle θ2 satisfy the following Conditional Expressions (1) to (3), the balance between maximizing the reducing effect of iron loss and minimizing the reduction in magnetic flux density becomes more optimized.

[0068] From the point of view of optimizing the balance between maximizing the reducing effect of iron loss and minimizing the reduction in magnetic flux density, it is more preferable that the lower limit of the first angle θ1 be 20° and one difference value (θ2- θ1) between the second angle θ2 and the first angle θ1 is 15° or greater.
[0069] However, in a case of observing the cross-section of the transverse groove of the groove 5 with an electron microscope and the like, a threshold between the groove 5 and the steel sheet surface 2a, the contour of the groove 5 and the like can not be clear. Consequently, it is important to know how to specify the average depth D of the groove 5, the deepest portion (depth of the groove Da) of the groove 5, the center of groove width GC, the first surface of the groove 5a and the second surface of the groove 5b . An example of the specification method will be described below.
[0070] As illustrated in Figure 4, in a case where the groove 5 is seen from the sheet thickness direction Z (in plan view of the groove 5), an observation strip 50 is defined for a part of the groove 5 and a plurality of (n) virtual lines L1 to Ln are virtually defined in the observation strip 50 along the slot extension direction. It is preferred that the observation strip is defined in a region that excludes an end in the extending direction of the groove 5 (i.e. a region where a shape of the groove bottom is stable). For example, the observation range 50 may be an observation region where a length in the groove extension direction is approximately 30 µm to 300 µm. Then, when measuring the surface roughness of the groove 5 along the virtual line L1 using a laser-type surface roughness measuring device and the like, as illustrated in Figure 5A, a measurement cross-section curve MCL1, which constitutes an outline of the groove 5 in the groove extension direction, is obtained in a shape that conforms to the virtual line L1.
[0071] After obtaining a cross-section curve by applying a low-pass filter (cut-off value: As) to the MCL1 measurement cross-section curve obtained in relation to the virtual line L1 as described above, when a band (cut-off value: Àf, Àc) is applied to the cross-cut curve to remove long wavelength components and short wavelength components from the cross-cut curve, as illustrated in Figure 5B, a ripple curve LWC1, which constitutes a contour of the groove 5 in the groove extension direction, is obtained in a shape that conforms to the virtual line L1. Ripple curve is a type of contour curve in combination with the following roughness curve. The roughness curve is a contour curve that is suitable for expressing particularly the surface roughness of the contour accurately, and the ripple curve is a contour curve that is suitable for simplifying the contour shape with a smooth line.
[0072] As illustrated in Figure 5B, when using the LWC1 waviness curve, the distances (depths e1 to ek: unit is μm) in the direction of sheet thickness Z between the surface of sheet steel 2a and the contour (or that is, the waviness curve LWC1) of groove 5 are obtained at a plurality of (k) positions along the virtual line L1. In addition, an average value (average groove depth D1) of depths e1 to ek is obtained.
[0073] The average depths D2 to Dn are also obtained in relation to other virtual lines L2 to Ln according to the same measurement method.
[0074] In addition, it is necessary to measure a position (height) of the surface of steel sheet 2a in the Z direction beforehand to measure the distance between the surface of steel sheet 2a and the contour (waving curve LWC1) of groove 5 For example, the position (height) in the Z direction can be measured with respect to a plurality of locations on the steel sheet surface 2a in the observation range 50 using the laser-type surface roughness measuring device, and a average value of measurement results can be used as the height of the 2a steel sheet surface.
[0075] In this mode, between the virtual lines L1 to Ln, a virtual line, which conforms to the groove extension direction and satisfies a condition where an average depth becomes the maximum, is selected as a groove reference line BL and an average depth that is obtained with respect to the groove reference line BL is defined as an average depth D (unit: μm) of the groove 5. For example, between the mean depths D1 to Dn that are obtained with respect to the respective virtual lines L1 to Ln, in a case where the average depth D3 is the maximum, as illustrated in Figure 6, the virtual line L3 is defined as the groove reference line BL, and the average depth D3 which is obtained relative to virtual line L3 is defined as the mean depth D of groove 5.
[0076] Furthermore, as illustrated in Figure 6, in a case where the groove 5 is seen from the sheet thickness direction Z (in a case of a plan view of the groove 5), a virtual line LS, which is parallel to a direction (groove width direction: a direction parallel to the rolling direction X in this mode) perpendicular to the groove extension direction, is virtually defined in observation range 50. The virtual line LS can be adjusted in an arbitrary height in the sheet thickness direction Z. When measuring the surface roughness of the steel sheet 2, including the groove 5 along the virtual line LS, using a laser-type surface roughness measuring device and the like , as illustrated in Figure 7A, an MLS measurement cross-section curve, constituting a contour of the groove 5 in the groove width direction, is obtained in a shape that conforms to the virtual line LS.
[0077] After obtaining a cross-section curve by applying a low-pass filter (cut-off value: As) to the MLS measurement cross-section curve obtained in relation to the virtual line L1 as described above, when a band (cut-off value: Àf, Àc) is applied to the cross-cut curve to remove long wavelength components and short wavelength components from the cross-cut curve, as illustrated in Figure 7B, a ripple curve SWC (later in this document, called a transverse slot waviness curve), which constitutes a contour of the slot 5 in the slot width direction, is obtained in a shape that conforms to the virtual line LS. Ripple curve is a type of contour curve in combination with the following roughness curve. The roughness curve is a contour curve that is suitable for expressing particularly the surface roughness of the contour accurately, and the ripple curve is a contour curve that is suitable for simplifying the contour shape with a smooth line.
[0078] As illustrated in Figure 7B, when using the SWC transverse groove ripple curve, the distances (depths d1 to dm: unit is μm) in the direction of sheet thickness Z between the steel sheet surface 2a and the contours (i.e. the transverse slot waviness curve SWC) of the slot 5 in the slot width direction are obtained at a plurality of (m) positions along the virtual line LS. In this mode, as illustrated in Figure 7B, the SWC ripple curve has a minimum value, and it does not have a local maximum value. In this modality, among the depths d1 to dm obtained as described above, the highest value is defined as a groove depth Da (depth of the deepest portion of groove 5). Furthermore, as illustrated in Figure 7B, in the transverse slot waviness curve SWC, a region that satisfies the following Conditional Expression (4) is defined as a slot region 5c, and the center of the slot region 5c in the width direction slot is defined as a GC slot center. di<0.05xDa... (4)
[0079] (Provided that i is an integer from 1 to m)
[0080] In addition, as illustrated in Figure 8, in the SWC transverse groove waviness curve representing the contour of the groove 5, the line segments, which are slanted from the steel sheet surface 2a towards the deeper portion of the groove 5 are defined as a first groove surface 5a and a second groove surface 5b. As illustrated in Figure 8, at the first groove surface 5a in the transverse groove waviness curve SWC, a point at which a depth of the steel sheet surface 2a in the sheet thickness direction Z becomes 0.05xDa, is defined as P1 and a point, where the depth of sheet steel surface 2a in the sheet thickness direction Z becomes 0.50xDa, is defined as P2. At the second groove surface 5b in the SWC transverse groove ripple curve, a point where the depth of the steel sheet surface 2a in the sheet thickness direction Z becomes 0.05xDa, is defined as P3 and a point, where the depth of sheet steel surface 2a in the sheet thickness direction Z becomes 0.50xDa, it is set to P4.
[0081] Furthermore, as illustrated in Figure 8, a straight line connecting point P1 and point P2 on the first groove surface 5a is configured as a first straight line of groove end LH1 and a straight line connecting the point P3 and the point P4 on the second groove surface 5b is configured as a second straight groove end line Lb2. Thus, an angle, which is formed by the first straight groove end line Lb1 obtained from the transverse groove waviness curve SWC and the sheet thickness direction Z, is a first angle θ1 and an angle, which is formed by the second straight groove end line Lb2 obtained from the transverse groove waviness curve SWC and the sheet thickness direction Z, is a second angle θ2.
[0082] As described above, this mode exemplifies a case in which the first groove surface 5a is subjected to linear approximation by the straight line connecting the two points on the first groove surface 5a, but another method can be used as a method for linear approximation of the first groove surface 5a. For example, the first groove surface 5a can be subjected to linear approximation using a least squares method. This also applies to the linear approximation of the second groove surface 5b.
[0083] Furthermore, a groove width W of the groove 5 is defined as a distance between an intersection of the steel sheet surface 2a and the first groove surface 5a, and an intersection of the steel sheet surface 2a and the second groove surface 5b. Specifically, as illustrated in Figure 8, when viewed in the transverse slot cross-section of slot 5, a length of a line segment (slot opening) connecting point P1 and point P3 can be obtained. It is preferable that the slot width W is 10 µm to 250 µm in order to preferably obtain the magnetic domain refinement effect.
[0084] However, in a manufacturing process of a wound core, the bending work is carried out in relation to the electrical steel sheet with oriented grain 1. In an electrical steel plate in which a groove is machined with a laser, he found It should be noted that it is highly likely that the steel sheet will be fractured from a groove portion as a base point during a bending process. Consequently, from a result obtained by the present inventors through a detailed analysis of a crystal structure of the groove portion, they found that fracture is likely to occur in a case where there is a small grain size portion in the groove portion. groove portion, that is, in a case where there is a melted and resolidified layer in the groove portion.
[0085] In steel sheet 2, in the case where there is the melted layer and resolidified in groove 5 of steel sheet 5, when the electrical steel sheet with oriented grain 1 is flexed, it is likely that the melted layer will fracture and resolidified as a base point. That is, the present inventors reached the following conclusion. When there is the molten and resolidified layer in groove 5 of steel sheet 2, the flexural resistant characteristics of electrical steel sheet with oriented grain 1 deteriorate.
[0086] Consequently, in this embodiment, in steel sheet 2, it is preferred that an average grain size of a crystal grain that is in contact with groove 5 is 5 µm or more. In a case where the fused and resolidified layer, which is derived from the formation of groove 5, exists on the periphery of groove 5. There is a high possibility that preferential flexural strength characteristics will not be obtained. Consequently, it is preferable that the fused and resolidified layer does not exist on the periphery of the groove 5. In a case where the fused and resolidified layer does not exist on the periphery of the groove 5, an average grain size of one crystal grain (recrystallized grain). secondary surface) that is in contact with slot 5 becomes 5 µm or more. For example, the crystal shape of the molten and resolidified layer can become a long columnar shape that extends in a vertical direction from the surface. Accordingly, in the grain size of the crystal grain (secondary recrystallized grain) that is in contact with groove 5, it is preferable that a short axis length of a columnar grain and not a long axis length is 5 µm or greater. That is, in the crystal grain that is in contact with groove 5, when viewed on an observation surface that is parallel to a sheet surface of the electrical steel sheet with oriented grain 1, it is preferable that the average grain size be 5 µm or greater. For example, crystal grain grain size can be obtained with reference to a typical crystal grain size measurement method such as ASTM and E112, or it can be obtained according to a backscattered electron diffraction pattern method ( EBSD). For example, the groove 5, which does not include the melted and solidified region, can be obtained according to the following manufacturing method.
[0087] Particularly, even in a case where groove 5 is observed over the transverse groove cross-section, it is more preferred than a grain size of a crystal grain (secondary recrystallized grain), which exists on one side bottom of groove 5 in steel sheet 2, in a direction of sheet thickness is equal to or greater than 5 μm and equal to or less than a sheet thickness of steel sheet 2. The characteristic represents that a fine grain layer (layer fused and resolidified), where a grain size of a crystal grain in a sheet thickness direction is approximately 1 µm, does not exist on an underside of groove 5 in steel sheet 2.
[0088] As illustrated in Figure 9, in a case where the steel sheet 2 is seen from the sheet thickness direction Z, a grain size of a secondary recrystallized grain, which exists in the steel sheet 2, becomes approximately 100 mm to maximum. On the other hand, in a case where the groove 5 is seen in the transverse groove cross-section, a grain size of a crystal grain (secondary recrystallized grain), which exists on an underside of the groove 5 in the steel sheet 2 , in the direction of sheet thickness becomes approximately 5 µm to the minimum, and becomes approximately the plate thickness (eg 0.1 to 0.4 mm) of steel sheet 2 to the maximum. Consequently, it is preferable that the lower grain size limit of the secondary recrystallized grain, which exists on a lower side of the groove 5 in the steel sheet 2, in the sheet thickness direction is set to 5 µm, and the upper limit is set. for the thickness of the steel sheet 2. Thus, in a case of employing a configuration where there is no melted and resolidified layer on an underside of the groove 5, it is possible to improve the bending resistant characteristics of the electric steel sheet with oriented grain 1.
[0089] Furthermore, the thickness of the insulating film 4 in a region where the groove 5 is formed is greater than the thickness of the insulating film 4 in other regions. Consequently, the adhesiveness between the steel sheet 2 and the insulating film 4 in the region where the groove 5 is formed worsens compared to other regions. As a result, cracking or peeling is likely to occur in insulating film 4 at the periphery of groove 5. When cracking or peeling occurs in insulating film 4, rust occurs in steel sheet 2.
[0090] Consequently, in this mode, as illustrated in Figure 2, in a case where the slot 5 is seen in a cross section (longitudinal slot cross section) including the slot extension direction and the sheet thickness direction Z , an arithmetic mean height Ra of a roughness curve, which constitutes the contour of the lower groove region 5d of groove 5, is 1 µm to 3 µm, preferably 1.2 µm to 2.5 µm, and more preferably , 1.3 µm to 2.3 µm. An average length RSm of a roughness curve element constituting the contour of the lower groove region 5a is 10 µm to 150 µm, preferably 40 µm to 145 µm and more preferably 60 µm to 140 µm.
[0091] When the surface roughness parameters (Ra and RSm) satisfy the ranges described above, the lower groove region 5h of groove 5 becomes a constant rough surface. Consequently, the adhesiveness between the steel sheet 2 and the glass film 3 or the insulating film 4 is improved due to a clamping effect. Accordingly, cracking or peeling is less likely to occur in the glass film 3 or insulating film 4 at the periphery of the groove 5. As a result, it is possible to improve the rust resistance of the electrical steel sheet with oriented grain 1 .
[0092] However, as illustrated in Figure 3, it cannot be said that the depth of groove 5 is always constant in the width direction of groove 5. Consequently, it is important to know how to specify the lower region of groove 5d in a case in that the groove 5 is seen in cross-section of the longitudinal groove. Later in this document, a description will be provided of an example of a method of specifying the lower region of slot 5d in a case where slot 5 is seen in longitudinal slot cross-section.
[0093] Figure 10 is a cross-sectional view of an arrow taken along line CC in Figure 6. That is, Figure 10 is a view when slot 5 is seen in a cross-section of longitudinal slot including the groove reference line BL and the sheet thickness direction Z. As illustrated in Figure 10, a curve, which is obtained by converting a curve into a measurement cross-section that constitutes a contour of the groove 5 in the cross-section of Longitudinal groove in a waving curve is defined as an LWC longitudinal grooving waving curve. The LWC longitudinal groove waviness curve is obtained as follows. After obtaining a cross-cut curve by applying a low-pass filter (cut-off value: As) to the measurement cross-section curve obtained in relation to the BL groove reference line, a band filter (cut-off value: Àf, Àc) is applied to the cross-cut curve to exclude long wavelength components and short wavelength components from the cross-section curve, thus obtaining the longitudinal groove waviness curve LWC. Figure 10 is a cross-sectional view of an arrow taken along line CC in Figure 6. That is, Figure 10 is a view when slot 5 is viewed in longitudinal slot cross-section including slot reference line BL and the sheet thickness direction Z. In this mode, as illustrated in Figure 10, in a case where the groove 5 is seen in the longitudinal groove cross section including the BL groove reference line and the sheet thickness direction Z, the contour of groove 5 which is shown in observation strip 50 is defined as the lower region of groove 5d.
[0094] The lower groove region 5d of groove 5 is specified according to the method described above. That is, in this modality, as illustrated in Figure 11, an arithmetic mean height Ra of a roughness curve RC, which is obtained by converting a measurement cross-section curve that constitutes the contour of the groove lower region 5d of the groove 5 in the observation range 50 of the longitudinal groove cross section including the BL groove reference line and the sheet thickness direction Z is 1 µm to 3 µm, preferably 1.2 µm to 2.5 µm and with more preferably, 1.3 µm to 2.3 µm. An average length RSm of a roughness curve element, which is obtained by converting the measurement cross-section curve constituting the contour of the lower groove region 5d, is 10 µm to 150 µm, preferably 40 µm to 145 µm and even more preferably 60 µm to 140 µm. The RC roughness curve is obtained as follows. After obtaining a cross-cut curve by applying a low-pass filter with a cut-off value of As to a measurement cross-cut curve obtained with respect to the BL groove reference line, a high-pass filter (cut-off value : Àc) is applied to the cross-cut curve to exclude long wavelength components from the cross-cut curve, thus obtaining the LWC roughness curve. As described above, the RC roughness curve is a contour curve that is suitable for expressing particularly the surface roughness of the contour accurately. In addition, the definition of the mean arithmetic height Ra of the roughness curve RC, and the mean length RSm of the roughness curve element is in accordance with Japanese Industrial Standard JIS B 0601 (2013).
[0095] As described above, according to the electrical steel plate with oriented grain 1 of this modality, the groove 5, which satisfies the depth condition and the shape condition, is provided in the steel plate 2. Consequently, it is possible make the maximization of the reducing effect of iron loss and the minimization of the reduction in the magnetic flux density to be compatible with each other with satisfactory equilibrium.
[0096] Furthermore, according to this modality, a configuration, in which the melted and resolidified layer does not exist on an underside of the groove 5 in the steel sheet 2 is employed. Consequently, it is possible to improve the bending resistant characteristics of electrical steel sheet with oriented grain 1.
[0097] Furthermore, according to this modality, a configuration, in which the arithmetic mean height Ra of the roughness curve RC, which constitutes the contour of the lower groove region 5d, is 1 μm to 3 μm, and the length RSm mean of the roughness curve element is 10 μm to 150 μm is employed. Consequently, it is possible to improve the rust resistance of electrical steel sheet with oriented grain 1.
[0098] In addition, as illustrated in Figure 3, this modality exemplifies a state in which the glass film 3 does not exist in the groove 5 (that is, a state in which the average thickness of the glass film 3 is 0 μm) , but the glass film 3 whose average thickness is greater than 0 μm and equal to or less than 5 μm, and the insulating film 4, whose average thickness is 1 μm to 5 μm can be arranged in the groove 5. In addition, the film of glass 3 whose average thickness is 0.5 μm to 5 μm and insulating film 4 whose average thickness is 1 μm to 5 μm can be laid on the surface of sheet steel 2a. Furthermore, the average thickness of the glass film 3 in the groove 5 may be less than the average thickness of the glass film 3 on the steel sheet surface 2a.
[0099] When the thickness of the glass film 3 and the insulating film 4 is defined as described above, cracking or peeling is less likely to occur in the insulating film 4 on the periphery of the groove 5. 1 grain oriented electric steel sheet is further improved. Furthermore, when using a configuration where there is no glass film in slot 5 (ie a configuration where the average thickness of the glass film 3 in slot 5 is 0 µm), it is possible to further reduce a distance (groove width) between facing groove wall surfaces. Consequently, it is possible to further improve the reducing effect of iron loss due to groove 5.
[00100] In addition, the modality exemplifies the grain-oriented electrical steel sheet 1 including the glass film 3. However, since the glass film 3 is not an essential constitutive element as described above, even when the invention is applied to a grain-oriented electrical steel sheet consisting only of steel sheet 2 and insulating film 4, the same effect can be obtained. In the grain-oriented electrical steel sheet that consists only of the steel sheet 2 and the insulating film 4, the insulating film 4 whose average thickness is 1 μm to 5 μm can be arranged in the groove 5, and an insulating film 4 whose thickness medium is 1 µm to 5 µm can be laid on the surface of 2a steel sheet.
[00101] In the following, the description will be given of a method of manufacturing the electric steel sheet with oriented grain 1 according to this modality.
[00102] Figure 12 is a flowchart illustrating the manufacturing processes of electrical steel sheet with grain oriented 1. As illustrated in Figure 12, in a first casting process S01, cast steel, which has a chemical composition that includes, in terms of mass fraction, Si: 0.8% to 7%, C: more than 0% and equal to or less than 0.085%, Acid-soluble Al: 0% to 0.065% N: 0% to 0.012%, Mn: 0% to 1%, Cr: 0% to 0.3% Cu: 0% to 0.4%, P: 0% to 0.5%, from Sn: 0% to 0.3%, from Sb: 0% to 0.3% Ni: 0% to 1%, S: 0% to 0.015%, Se: 0% to 0.015%, and the rest including Fe and unavoidable impurities, is supplied to a casting machine continuous, and a plate is continuously produced.
[00103] Subsequently, in an S02 hot rolling process, the slab obtained in the S01 casting process is heated to a predetermined temperature (for example, 1150 to 1400°C), and the hot rolling is carried out in relation to the slab . According to this, for example, a hot rolled steel sheet which has a thickness of 1.8 to 3.5 mm is obtained.
[00104] Subsequently, in an S03 annealing process, an annealing treatment is carried out in relation to the hot rolled steel sheet obtained in the S02 hot rolling process under a predetermined temperature condition (for example, a condition where the heating is carried out at 750 to 1200°C for 30 seconds to 10 minutes). Subsequently, in an S04 cold rolling process, pickling is carried out in relation to a surface of the hot rolled steel sheet which is subjected to the annealing treatment in the S03 annealing process and then the cold rolling is performed in relation to the hot rolled steel sheet. Accordingly, for example, a cold-rolled steel sheet having a thickness of 0.15 to 0.35 mm is obtained.
[00105] Subsequently, in an S05 decarburizing annealing process, a heat treatment (ie, an annealing treatment with decarburization) is carried out in relation to the cold-rolled steel sheet obtained in the S04 cold-rolling process under a predetermined temperature condition (for example, a condition where heating is carried out at 700 to 900°C for 1 to 3 minutes). When annealing treatment with decarburization is carried out, on the cold rolled steel sheet, the carbon is reduced to a predetermined amount or less, and the primary recrystallized structure is formed. Furthermore, in the S05 decarburization annealing process, an oxide layer, which contains silica (SiO2) as a major component, is formed on a surface of the cold-rolled steel sheet.
[00106] Subsequently, in an annealing separation agent application process S06, an annealing separation agent, which contains magnesia (MgO) as a main component, is applied to the surface (the surface of the oxide layer) of the sheet of cold rolled steel. Subsequently, in an S07 final annealing process, a heat treatment (ie a final annealing treatment) is carried out in relation to the cold rolled steel sheet onto which the annealing separation agent is applied under a temperature condition predetermined (for example, a condition where heating is carried out at 1100 to 1300°C for 20 to 24 hours). When the final annealing treatment is carried out, secondary recrystallization takes place on the cold rolled steel sheet, and the cold rolled steel sheet is purified. As a result, it is possible to obtain a cold-rolled steel sheet which has the chemical composition described above as steel sheet 2 and in which a crystal orientation is controlled so that an easily magnetized geometric axis of a crystal grain and the rolling direction X correspond to each other (ie steel sheet 2 in a state before groove 5 is formed in electrical steel sheet with grain oriented 1).
[00107] In addition, when the final annealing treatment is carried out as described above, an oxide layer containing silica as a major component reacts with the annealing separating agent which contains magnesia as a major component, and the glass film 3 which includes a composite oxide such as forsterite (Mg2SiO4) is formed on a surface of steel sheet 2. In the final annealing process S07, the final annealing treatment is carried out in a state where steel sheet 2 is rolled into spiral in a coil format. The glass film 3 is formed on the surface of the steel sheet 2 during the final annealing treatment. Consequently, it is possible to prevent adhesion to the steel sheet 2 which is spirally wound into a coil shape.
[00108] Subsequently, in an S08 laser irradiation process, the surface (only one surface) of the steel sheet, on which the glass film is formed, is irradiated with a laser to form a plurality of grooves 5, which extend in a direction that crosses the X-roll direction, on the surface of sheet steel 2 along the X-roll direction at a predetermined interval. Later in this document, the S08 laser irradiation process will be described in detail with reference to Figure 13 to Figure 15.
[00109] As illustrated in Figure 13, in the laser irradiation process S08, a laser light YL, which is emitted from a laser light source (not shown) is transmitted to a laser irradiation apparatus 10 through a optical fiber 9. A polygon mirror (not shown) and a rotary drive device (not shown) of the polygon mirror are embedded in the laser irradiation apparatus 10.
[00110] The laser irradiation apparatus 10 irradiates the surface of the steel sheet 2 with the YL laser light and scans the steel sheet 2 with the YL laser light in a direction that is approximately parallel to the width direction of the YL sheet. 2 steel plate due to polygon mirror rotation.
[00111] An auxiliary gas 25 such as air and an inert gas is sprayed to a portion of the steel sheet 2 which is irradiated with laser light YL in combination with irradiation with laser light YL. Examples of the inert gas include nitrogen, argon and the like. The auxiliary gas 25 has a function of removing a component that is melted or evaporated from the steel sheet 2 with laser irradiation. The YL laser light hits the steel sheet 2 without being blocked by the molten or evaporated component due to the sparging of auxiliary gas 25. Consequently, the groove 5 is stably formed. Furthermore, it is possible to suppress the component from being fixed to the steel plate 2 due to the sparging of the auxiliary gas 25. As a result, the groove 5 is formed along a scanning line of the laser light YL. Furthermore, as described above, once the component is removed due to the sparging of auxiliary gas 25, it is possible to obtain a configuration where the melted and resolidified layer does not exist on an underside of the groove 5.
[00112] In the S08 laser irradiation process, the surface of the steel sheet 2 is irradiated with the YL laser light while the steel sheet 2 is guided along a sheet displacement direction that corresponds to the rolling direction X. Here, a rotational speed of the polygon mirror is controlled in sync with a driving speed of the steel sheet 2 so that the groove 5 is formed at a predetermined interval PL along the rolling direction X. As a result, as illustrated in Figure 13, a plurality of grooves 5, which cross the rolling direction X, are formed in the surface of the steel sheet 2 at the predetermined interval PL along the rolling direction X.
[00113] As the laser light source, for example, a fiber laser can be used. A high-performance laser such as a YAG laser, a semiconductor laser, and a CO2 laser, which are typically used in industry, can be used as the laser light source. Furthermore, a pulse laser or a continuous wave laser can be used as the laser light source as long as slot 5 can be stably formed. Like the YL laser light, it is preferable to use a single-mode laser that has a property of high light condensation and is suitable for slit forming.
[00114] As the irradiation conditions with the YL laser light, for example, it is preferable that a laser output be set to 200 W to 3000 W, a light dew point diameter of the YL laser light in the lamination direction X (ie, a diameter that includes 86% of the laser output, later in this document, called 86% of diameter) is set to 10 μm to 1000 μm, a light dew point diameter (86% of diameter) YL laser light in the Y-plate width direction is set to 10 μm to 1000 μm, a laser scan speed is set to 5 m/s to 100 m/s, and a laser scan pitch (PL interval) is adjusted to 4mm to 10mm. The laser irradiation conditions can be properly adjusted to get a desired groove depth D. For example, in a case of getting a deep groove depth D, the laser scan speed can be set to be slow, and laser yield can be set to be high.
[00115] As illustrated in Figure 14A, in a case where the slot 5 is seen from the laser scanning direction (slot extension direction), when an angle (laser radiation angle) between the thickness direction of sheet Z and the laser light irradiation direction YL is set to Φ1, it is preferable that the laser irradiation angle Φ1 is set in a range of 10 to 45° so that the first desired angle θ1 in the groove cross section groove 5 is obtained. Accordingly, it is possible to obtain a cross-sectional shape of the slot 5 in the asymmetrical shape as illustrated in Figure 3. In addition, the auxiliary gas 25 is sprayed to adapt to the laser light YL. However, in a case where the laser irradiation angle Φ1 is defined in the range, a spray direction (spray angle) of the auxiliary gas 25 is not particularly limited.
[00116] On the other hand, when the sprinkler direction of the auxiliary gas 25 is defined as follows, it is possible to obtain the cross-sectional shape of the slot 5 in the asymmetrical shape as shown in Figure 3. As shown in Figure 14B, in a plan view of the steel sheet 2 which is driven along the direction of travel of sheet TD which is parallel to the rolling direction X, the auxiliary gas 25 is sprayed to conform to laser light YL from a direction having an inclination of an angle 02 with respect to the SD laser scanning direction (direction parallel to the plate width direction Y) of the laser light YL. Also, as illustrated in Figure 14C, when the steel sheet 2 which is transferred along the plate travel direction TD is seen from the plate width direction Y (laser scan direction SD), the auxiliary gas 25 is sprinkled to adapt to YL laser light from a direction that has an inclination of an angle 033 with respect to the steel sheet surface 2a. It is preferable that angle 02 is defined in a range of 90° to 180°, and angle 03 is defined in a range of 1° to 85°.
[00117] In addition, it is preferable to perform an atmosphere control so that the amount of particles, which exist in an atmosphere of displacement of sheet steel sheet 2 and have a diameter of 0.5 μm or more, becomes equal or greater than 10 pieces and less than 10000 pieces per 1 CF (cubic feet).
[00118] Particularly, when the auxiliary gas spray angle 02 in relation to the laser scanning direction and the auxiliary gas spray angle 03 in relation to the steel sheet surface 2a are defined in the ranges described above, it is possible to control the cross-sectional shape of the groove 5 as the asymmetric shape illustrated in Figure 3, and it is possible to control the surface roughness (Ra, RSm) of the lower region of groove 5d precisely. In addition, when the quantity of particles, which exist in the plate-displacement atmosphere and having a diameter of 0.5 μm or more, is adjusted in the range described above, it is possible to control the surface roughness (particularly, RSm) of the region 5d groove bottom with more precision. In addition, it is preferable to set an auxiliary gas flow rate 25 in a range of 1000 litres/minute. However, in a case where the flow rate of the auxiliary gas 25 is 50 liters/minute or less, the molten layer and resolidified on an underside of groove 5 is likely to occur. lower flow rate of auxiliary gas 25 is greater than 50 liters/minute.
[00119] In the related art, in a case of forming a groove with laser irradiation, an auxiliary gas is sprayed towards a steel plate surface to adapt to a laser from one direction (plate thickness direction ) which is perpendicular to a sheet steel surface so as to efficiently form a groove with a rectangular cross section (i.e. a groove with a bilaterally symmetrical shape). The present inventors made a thorough investigation regarding the configuration, and they obtained the following knowledge. When the YL laser light irradiation direction and the auxiliary gas spray direction 25 are defined three-dimensionally as illustrated in Figure 14A to Figure 14C, it is possible to control the cross-sectional shape of slot 5 as the asymmetrical shape that satisfies the Expression (1) to Expression (3) accurately. Furthermore, when the amount of particles in the atmosphere of plate displacement during laser irradiation is defined, it is possible to control the surface roughness (Ra, RSm) of the lower 5d slot region precisely.
[00120] In addition, the present inventors reached the following finding. When the groove having the asymmetrical shape, which satisfies Expression (1) to Expression (3), is formed in the grain-oriented electrical steel sheet according to the innovative manufacturing method described above, it is possible to make the maximization of the Iron loss reducing effect and minimization of the reduction in magnetic flux density are compatible with each other with a satisfactory balance, and the rust resistance can be further increased. The present inventors carried out the present invention in accordance with the findings. Consequently, the method of manufacturing the grain-oriented electrical steel sheet according to this modality (particularly the laser irradiation process) is an innovative manufacturing method that is not anticipated by those skilled in the art, and the electrical steel sheet with oriented grain 1 which is obtained according to the manufacturing method also has an innovative configuration (the cross-sectional shape of the groove 5 and the surface roughness of the lower groove region 5d) which cannot be predicted by those skilled in the art.
[00121] In a case where it is difficult to form the groove 5 in the entirety of the steel sheet 2 in the width direction of sheet Y with a laser irradiation apparatus 10, as illustrated in Figure 15, the groove 5 can be formed in the the entirety of the steel sheet 2 in the plate width direction Y using a plurality of laser irradiation apparatus 10. In that case, as illustrated in Figure 15, the plurality of laser irradiation apparatus 10 is arranged along the rolling direction X at a predetermined interval. Furthermore, when viewed from the lamination direction X, the positions of the respective laser irradiation apparatus 10 in the width direction of the plate Y are adjusted so that the laser scanning lines of the respective laser irradiation apparatus 10 do not overlap. When employing the laser irradiation method illustrated in Figure 15, it is possible to form a plurality of grooves 5 as illustrated in Figure 1 in the steel sheet surface 2a.
[00122] Again with reference to Figure 12, in an insulating film forming process S09, for example, an insulating coating solution containing colloidal silica and a phosphate is applied to the surface of steel sheet 2a, where groove 5 is formed according to the S08 laser irradiation process, from an upper side of the glass film 3. Then, when a heat treatment is carried out under a predetermined temperature condition (eg 840 to 920°C), by Finally, it is possible to obtain the grain-oriented electrical steel sheet 1 including the steel sheet 2 in which the groove 5 is formed, the glass film 3, and the insulating film 4 as illustrated in Figures 1 to 3.
[00123] The steel sheet 2 of the oriented grain electric steel sheet 1 manufactured as described above contains, as chemical components in terms of mass fraction, Si: 0.8% to 7%, C: more than 0% and equal to or less than 0.085%, Acid-soluble Al: 0% to 0.065% N: 0% to 0.012%, Mn: 0% to 1%, Cr: 0% to 0.3% Cu: 0% to 0 .4%, P: 0% to 0.5%, from Sn: 0% to 0.3%, from Sb: 0% to 0.3% Ni: 0% to 1%, S: 0% to 0.015 %, Se: 0% to 0.015%, and the remainder including Fe and unavoidable impurities.
[00124] In addition, the modality exemplifies a case of employing a manufacturing process in which the groove 5 is formed on the steel sheet surface 2a through laser irradiation before the insulating film 4 is formed on the steel sheet surface 2a, and then the insulating film 4 is formed on the steel sheet surface 2a. This modality is not limited to this and can employ a manufacturing process in which after the insulating film 4 is formed on the steel sheet surface 2a, the steel sheet surface 2a is irradiated with laser light YL from one side top of insulating film 4 to form groove 5 in sheet steel surface 2a. In that case, slot 5 immediately after laser irradiation is exposed to the outside. Consequently, it is necessary to form the insulating film 4 on the steel sheet 2 after the formation of the groove 5. Alternatively, in this mode, the glass film 3 or the insulating film 4 can be formed after the groove 5 is formed in the steel plate. two.
[00125] Consequently, the oriented grain electric steel sheet 1, for which the high temperature annealing for the secondary recrystallization is completed and the coating of the glass film 3 and the insulating film 4 is completed, is included in the electrical steel sheet with grain oriented according to this modality, and a magnetic steel sheet with grain oriented before the completion of coating of the glass film 3 or the insulating film 4 and after the formation of the groove 5 is also included in the plate. electric steel with oriented grain. In other words, a final product can be obtained by performing the formation of the glass film 3 and the insulating film 4 as a post-process using electrical steel plate with grain oriented according to this modality. Furthermore, as described above, in a case of removing the glass film 3 or the insulating film 4 from the grain-oriented electrical steel sheet 1 wherein the glass film 3 or the insulating film 4 is formed according to the method of film removal described above, it is confirmed that the shape or roughness of the groove 5 is approximately the same as before the formation of the glass film 3 or the insulating film 4.
[00126] In addition, the modality exemplifies a case of performing the S08 laser irradiation process after the S07 final annealing process, but the laser irradiation process can be performed between the S04 cold lamination process and the process of annealing by decarburization S05. That is, when laser irradiation and auxiliary gas spraying is carried out in relation to the cold rolled steel sheet that is obtained in the cold rolling process S04, after the formation of groove 5 in the surface of steel sheet 2a of cold-rolled steel sheet, decarburizing annealing can be performed in relation to cold-rolled steel sheet. EXAMPLES
[00127] Later in this document, an effect of an aspect of the invention will be described more specifically with reference to the examples, but a condition in the Examples is a conditional example that is employed to confirm operability and an effect of the invention, and the invention does not is limited to a conditional example. The invention may employ various conditions as long as the object of the invention is achieved without departing from the essence of the invention. (Verification 1 of the Balance between the Maximization of Iron Loss Reducing Effect and the Minimization of Magnetic Flux Density Reduction)
[00128] First, a grain-oriented electrical steel sheet used in Verification 1 was manufactured as follows.
[00129] The hot lamination was carried out in relation to a board having a chemical composition that contains, in terms of mass fraction, Si: 3.0%, C: 0.08%, Acid-soluble Al: 0.05 %, N: 0.01%, Mn: 0.12%, Cr: 0.05%, Cu: 0.04%, P: 0.01%, Sn: 0.02%, Sb: 0. 01%, Ni: 0.005%, S: 0.007%, Se: 0.001%, and the rest including Fe and unavoidable impurities to obtain a hot rolled steel sheet having a thickness of 2.3 mm.
[00130] Subsequently, an annealing treatment was carried out on the hot rolled steel sheet under a temperature condition where heating was carried out at 1000°C for one minute. Pickling was carried out against a surface of the hot rolled steel sheet which was subjected to annealing treatment and then cold rolling was carried out against the hot rolled steel sheet to obtain a hot rolled steel sheet cold having a thickness of 0.23 mm. Subsequently, a decarbonating annealing treatment was carried out on the cold rolled steel sheet under a temperature condition in which heating was carried out at 800°C for two minutes and then an annealing separating agent containing magnesia (MgO ) as a main component was applied on the surface of cold rolled steel sheet.
[00131] Subsequently, a final annealing treatment was carried out in relation to the cold rolled steel sheet onto which the annealing separating agent was applied under a temperature condition in which heating was carried out at 1200°C for 20 hours . As a result, a cold-rolled steel sheet (steel sheet in which a glass film has been formed on a surface thereof), which has the chemical composition described above and in which a crystal orientation is controlled so that the axis magnetization geometry of a crystal grain and the lamination direction to match, was obtained.
[00132] Subsequently, as described above, the steel sheet surface, on which the glass film was formed, was irradiated with a laser. Accordingly, a plurality of grooves, extending in a direction that crosses the rolling direction, were formed in the steel sheet surface in a predetermined range along the rolling direction.
[00133] As YL laser light irradiation conditions, a laser output was set in a range of 200 W to 3000 W, a light dew point diameter (86% diameter) of the YL laser light in the lamination direction X was set in a range of 10 μm to 1000 μm, a light dew point diameter (86% diameter) of laser light YL in the plate width direction Y was set in a range of 10 μm to 1000 μm, a laser scan speed was set in a range of 5 m/s to 100 m/s, and a laser scan step (PL range) was set in a range of 4 mm to 10 mm in order to obtain the depth of desired slot D.
[00134] In addition, the auxiliary gas spray angle 02 with respect to the laser scanning direction has been adjusted in a range of 90° to 180°, and the auxiliary gas spray angle 03 with respect to the plate surface. steel was adjusted in a range of 1° to 85° so as to obtain the first angle θ1 and the second angle θ2 which are desired in the cross-section of the cross-slot of the groove 5.
[00135] As described above, the insulating coating solution containing colloidal silica and a phosphate was applied to the steel sheet in which the groove was formed from an upper side of the glass film, and a heat treatment was performed under a temperature condition in which heating was carried out at 850°C for one minute. Accordingly, a grain-oriented electrical steel sheet including the steel sheet on which the groove was formed, the glass film, and the insulating film was finally obtained.
[00136] The steel sheet (steel sheet on which the groove was formed) in the grain-oriented electrical steel sheet, which was finally obtained, mainly contained Si: 3.0%.
[00137] According to the processes described above, as illustrated in Table 1, the grain-oriented electrical steel sheets, which are different in average groove depth D (unit: μm) and groove width W (unit: μm ), were prepared as grain oriented electrical steel sheet corresponding to Tests Nos 1 to 8. In all grain oriented electrical steel sheet corresponding to Tests 1 to 8, when groove 5 is seen in the groove cross section, the first angle θ1 was set to 45° and the second angle θ2 was set to 60°.
[00138] The grain-oriented electrical steel sheets corresponding to Test Nos. 3 to 7 are the grain-oriented electrical steel sheets of the present examples that satisfy a condition (Condition 1) in which the average groove depth D is greater than 10 μm and equal to or less than 40 µm, a condition (Condition 2) where the first angle θ1 is 0° to 50°, a condition (Condition 3) where the second angle θ2 is greater than the first angle θ1 and is 75° or less and a condition (Condition 4) where a difference value (θ2-θ1) between the second angle θ2 and the first angle θ1 is 10° or more. The grain oriented electrical steel sheets corresponding to Tests Nos 1, 2 and 8 are grain oriented electrical steel sheets from comparative examples that only satisfy Condition 2 to Condition 4. In all electrical steel sheets with corresponding oriented grain to Tests Nos 1 through 8, the existence rate α of the asymmetric groove region in the groove extension direction was 70% or more. Furthermore, in the examples, the laser irradiation conditions were set within the range described in the modality. In the comparative examples, laser irradiation conditions deviated from the range.
[00139] A loss of iron W17/50 and a reduction amount ΔB8 of a magnetic flux density B8 were measured with respect to each of the grain-oriented electrical steel sheets corresponding to Test Nos. 1 to 8. The measurement results are illustrated in Table 1. Furthermore, the loss of iron W17/50 represents an energy loss per unit weight (unit: W/kg) which is measured under excitation conditions of a magnetic flux density of 1.7 T and a frequency of 50 Hz with respect to a specimen (eg a 100 mm*500 mm specimen) of grain-oriented electrical steel sheets. In addition, the amount of reduction ΔB8 of a magnetic flux density B8 is a value (unit: G) obtained by subtracting a magnetic flux density B8 measured after grooving from a magnetic flux density B8 measured before of groove formation. The B8 magnetic flux density before grooving was 1.910 T (=19100 G), and the W17/50 iron loss before grooving was 0.97 W/kg.
[00140] As illustrated in Table 1, in the grain-oriented electrical steel sheets of comparative examples (the average groove depth D is 10 μm or less) corresponding to Tests Nos 1 and 2, the loss of iron W17/50 hardly varies compared to iron loss before groove formation (ie, the iron loss ameliorating effect is small). Furthermore, in the grain-oriented electrical steel sheet of a comparative example (the average groove depth D is greater than 40 μm) corresponding to Test No. 8, the amount of reduction ΔB8 of the magnetic flux density B8 is very large ( that is, a suppression effect of a reduction in magnetic flux density B8 is small).
[00141] On the other hand, as illustrated in Table 1, in the electrical steel sheets with oriented grain of the present examples corresponding to Tests Nos 3 to 7, the loss of iron W17/50 decreases considerably (that is, the effect of improving the loss of iron is greater) compared to the loss of iron before grooving, and the amount of reduction ΔB8 of the magnetic flux density B8 is suppressed to a relatively small value (ie, the suppression effect of the reduction in density of magnetic flux B8 is considerable). According to this Verification 1 as described above, it was confirmed that it is necessary to satisfy all of Conditions 1 to 4 to make the maximization of the reducing effect of iron loss and the minimization of the reduction in magnetic flux density to be compatible with each other with satisfactory balance. [TABLE 1]
(Verification 2 of the Balance between the Maximization of Iron Loss Reducing Effect and the Minimization of Magnetic Flux Density Reduction)
[00142] Next, as illustrated in Table 2, as the electrical steel sheets with oriented grain corresponding to Tests Nos. 9 to 14, the electrical steel sheets with oriented grain, which are different in a combination of the first angle θ1 and the second angle θ2, were prepared in the same process as Verification 1. On all grain-oriented electrical steel sheets corresponding to Test Nos. 9 to 14, the mean groove depth D was set to 20 µm, and the groove width W was set. to 70 µm.
[00143] Grain-oriented electrical steel sheets corresponding to Tests Nos 11 to 13 are grain-oriented electrical steel sheets from comparative examples that satisfy all of Conditions 1 to 4. Grain-oriented electrical steel sheets corresponding to Tests Nos 9 and 10 are grain oriented electrical steel sheet from comparative examples that satisfy Condition 1 only. The grain oriented electrical steel sheet corresponding to Test No. 14 is a grain oriented electrical steel sheet from a comparative example that satisfies only Conditions 1 to 3. As is the case with Verification 1, the iron loss W17/50 and the amount of reduction ΔB8 of the magnetic flux density B8 were measured in relation to each of the grained electrical steel sheets oriented corresponding to Tests Nos 9 to 14. The measurement results are illustrated in Table 2.
[00144] As illustrated in Table 2, in the oriented grain electrical steel sheets of the present examples corresponding to Tests Nos. 11 to 13, the iron loss W17/50 decreases considerably (ie, the iron loss improvement effect is higher) compared to the loss of iron before grooving, and the amount of reduction ΔB8 of magnetic flux density B8 is suppressed to a relatively small value (ie, the suppression effect of the reduction in magnetic flux density B8 is considerable).
[00145] On the other hand, in electrical steel sheets with oriented grain (θ1>50°) of the comparative examples corresponding to Tests Nos. 9 and 10, the iron loss improvement effect is smaller compared to Tests Nos. 11 to 13. In addition, on the grain-oriented electrical steel sheet of a comparative example (θ1=θ2) corresponding to Test No. 14, the iron loss improvement effect is approximately the same in Test Nos. 11 to 13, but the amount of reduction ΔB8 of magnetic flux density B8 is greater (ie, the suppression effect of reduction in magnetic flux density B8 is less) compared to Tests Nos. 11 to 13. According to this Verification 2 as described above , it was confirmed that it is necessary to satisfy the totality of Conditions 1 to 4 to make the maximization of the reducing effect of iron loss and the minimization of the reduction in the magnetic flux density to be compatible with each other with satisfactory equilibrium.
[00146] Furthermore, in an electrical steel sheet with oriented grain of the present example corresponding to Test No. 11-2, and an electrical steel sheet of a comparative example corresponding to Test No. 11-3, θ2 has been increased in same condition θ1 as Test No. 11.
[00147] In Test No. 11-3 (θ2> 75°) where θ2 does not satisfy Condition 3, the amount of decrease ΔB8 of magnetic flux density B8 is considerable (ie, the suppression effect of density reduction of magnetic flux B8 is small). According to this Verification 2 as described above, it was confirmed that it is necessary to satisfy all of Conditions 1 to 4 to make the maximization of the reducing effect of iron loss and the minimization of the reduction in magnetic flux density to be compatible with each other with satisfactory balance. [TABLE 2]
(Verification 3 of the Balance between the Maximization of Iron Loss Reducing Effect and the Minimization of Magnetic Flux Density Reduction)
[00148] Next, as illustrated in Table 3, as the grain-oriented electrical steel sheets corresponding to Tests Nos. 15 to 18, the grain-oriented electrical steel sheets, which are different in the average groove depth D, the width of groove W, and a combination of the first angle θ1 and the second angle θ2, were prepared in the same process as Verification 1. On the grain-oriented electrical steel sheets corresponding to Test Nos. 15 and 16, the average groove depth D was adjusted. to 15 µm, and the slot width W has been set to 45 µm. On the grain-oriented electrical steel sheets corresponding to Test Nos. 17 and 18, the mean groove depth D was set to 25 µm, and the groove width W was set to 70 µm.
[00149] The grain oriented electrical steel sheets corresponding to Test Nos. 15 to 17 are the grain oriented electrical steel sheets of the present examples that satisfy all of Conditions 1 to 4. The corresponding grain oriented electrical steel sheets to Tests Nos. 16 and 18 are grain-oriented electrical steel sheets from comparative examples that only satisfy Conditions 1 to 3. As is the case with Verification 1, the iron loss W17/50 and the amount of density reduction ΔB8 of magnetic flux B8 were measured against each of the grain-oriented electrical steel sheets corresponding to Test Nos. 15 to 18. The measurement results are illustrated in Table 3.
[00150] As illustrated in Table 3, at the same average groove depth D, the iron loss improvement effect is also equal in each case. However, in a case where the cross-sectional shape of the slot is asymmetric (θ1 <θ2), the amount of reduction ΔB8 of the magnetic flux density B8 is smaller (ie, the suppression effect of the reduction in flux density magnetic B8 is larger) compared to a case where the groove cross-sectional shape (cross-groove waviness shape shape) is symmetrical (in a case where θ1=θ2). According to this Verification 3 as described above, it was confirmed that it is necessary to satisfy all of Conditions 1 to 4 to make the maximization of the reducing effect of iron loss and the minimization of the reduction in magnetic flux density to be compatible with each other with satisfactory balance. [TABLE 3]
(Checking Resistant Characteristics to Bending)
[00151] Next, as illustrated in Table 4, as the grain-oriented electrical steel sheets corresponding to Test Nos. 19 and 20, the grain-oriented electrical steel sheets, which are different in the presence or absence of the fine-grain layer (molten and resolidified layer) on an underside of the groove, were prepared in the same process as Verification 1. On the grain-oriented electrical steel sheets corresponding to Test Nos. 19 and 20, the average groove depth D was set to 20 μm, the slot width W was set to 70 µm, the first angle θ1 was set to 45°, and the second angle θ2 was set to 60°.
[00152] In the S08 laser irradiation process illustrated in Figure 12, the presence or absence of the fine grain layer on the underside of the groove was controlled by approximately adjusting the flow rate of the auxiliary gas 25 in a range of 10 liters/minute to 1000 liters/minute. Furthermore, the absence of the fine-grained layer represents that a condition (Condition 5) is satisfied. Specifically, in Condition 5, a plate width direction grain size of a secondary recrystallized grain, which exists on an underside of the groove, is set to equal to or greater than 5 µm and equal to or less than a thickness of plate of a steel plate. That is, the grain-oriented electrical steel sheet corresponding to Test No. 19 is a grain-oriented electrical steel sheet from a comparative example that satisfies Conditions 1 to 4 and does not satisfy Condition 5. The electrical steel sheet with oriented grain corresponding to Test No. 20 is a grain oriented electrical steel sheet of the present example that satisfies all of Conditions 1 to 5.
[00153] The auxiliary gas flow rate was adjusted to 40 liters/minute in Test No. 19 and 500 liters/minute in Test No. 20, thus controlling the presence or absence of the molten layer.
[00154] A repeated bending test was performed five times in relation to each of the electrical steel sheets with oriented grain corresponding to Tests Nos. 19 and 20 to confirm whether or not fracture occurred in the groove periphery. As a result, in the grain-oriented electrical steel sheet of the present example corresponding to Test No. 20, the fracture did not occur in the groove periphery. Through verification, it was confirmed that the bending characteristics of electrical steel sheet with grain oriented are improved when Condition 5 is satisfied in addition to Conditions 1 to 4. [TABLE 4]
(Rust Resistance Verification 1)
[00155] Next, the rust resistance of an electrical steel sheet with oriented grain, which satisfies Conditions 1 to 4 described above, and Conditions 6 and 7 that will be described below, was verified. (Condition 6)
[00156] In a case where the groove is seen in longitudinal groove cross-section, the arithmetic mean height Ra of a roughness curve that constitutes the contour of the groove's lower groove region is 1 µm to 3 µm. (Condition 7)
[00157] In a case where the groove is seen in longitudinal groove cross-section, the average height RSm of the roughness curve element that constitutes the contour of the lower groove region of the groove is 10 µm to 150 µm.
[00158] As illustrated in Table 5, like the present examples 1 to 8, the electrical steel sheets with oriented grain, which meet Conditions 1 to 4 and Conditions 6 and 7, were prepared in the same process as in Verification 1. In addition, like comparative examples 1 to 4, the grain-oriented electrical steel sheets, which meet Conditions 1 to 4 and do not meet Conditions 6 and 7, were prepared in the same process as in Verification 1. , in all of the present examples 1 to 8 and comparative examples 1 to 4, the average groove depth D was set to be greater than 10 μm and equal to or less than 40 μm, the first angle θ1 was set to 0° to 50° , the second angle θ2 was set to be greater than the first angle θ1 and equal to or less than 75°, and the slot width W was set to 10 μm to 250 μm.
[00159] In the S08 laser irradiation process illustrated in Figure 12, the auxiliary gas spray angle 02 in relation to the laser scanning direction, the auxiliary gas spray angle 03 in relation to the steel plate surface, the Auxiliary gas flow rate 25 and the amount of particles in the sheet displacement atmosphere were adjusted in the ranges described in the modality, thus obtaining an electrical steel sheet with oriented grain that satisfies Condition 6 and Condition 7. Particularly, it is possible control the surface roughness in the lower groove region accurately by adjusting the 02 and 03 auxiliary gas spray angles, and the amount of particles in the sheet displacement atmosphere.
[00160] In addition, the lower groove region of the groove has been specified in relation to each of the grain-oriented electrical steel sheets corresponding to Examples 1 to 8 and Comparative Examples 1 to 4 according to the specification method described in the modality . A laser-type surface roughness measuring device (VK-9700, manufactured by Keyence Corporation) was used to measure the surface roughness parameters (Ra, RSm) which represent the surface roughness in the lower region of the groove. .
[00161] The verification of rust resistance was carried out in relation to each of the electrical steel sheets with oriented grain corresponding to Present Examples 1 to 8 and Comparative Examples 1 to 4. Specifically, a specimen having a dimension of 30 mm on the one hand it was collected from each of the electrical steel sheets with oriented grain, the specimen was left as such for a week in an atmosphere of a temperature of 50°C and a humidity of 91%, and the evaluation was carried out. based on a variation in the weight of the specimen before being dropped and after being dropped. When rust occurs, the weight of the specimen increases. Consequently, since the amount of weight gain was less, the rust resistance was determined to be satisfactory. Specifically, the rust resistance of the specimen in which the amount of weight gain was 5.0 mg/m2 or less was rated as "satisfactory", and the rust resistance of the specimen in which the amount of increase in weight greater than 10.0 mg/m2 was assessed as "unsatisfactory". As shown in Table 5, from a result of checking the rust resistance of the grain-oriented electrical steel sheets corresponding to Present Examples 1 to 8, since a configuration satisfying Condition 7 was employed, it was confirmed that the strength The rust of the grain-oriented electrical steel sheets has been improved. [TABLE 5]

(Rust Resistance Verification 2)
[00162] Next, as illustrated in Table 6, a grain-oriented electrical steel sheet, which satisfies Conditions 1 to 4, satisfies Conditions 6 and 7 and does not include the glass film, was prepared as in the Present Example 9 using a known manufacturing method. In addition, grain-oriented electrical steel sheets, which satisfy Conditions 1 to 4, do not satisfy at least one of Conditions 6 and 7 and do not include the glass film, were prepared as Comparative Examples 5 to 7. In addition , in the entirety of Present Example 9 and Comparative Examples 5 to 7, the average groove depth D was greater than 10 μm and equal to or less than 40 μm, the first angle θ1 was 0° to 50°, the second angle θ2 was greater that the first angle θ1 is equal to or less than 75°, and the slot width W was 10 µm to 250 µm.
[00163] The chemical composition of the steel sheets was the same as in Verification 1 for rust resistance. As is the case with Rust Resistance Verification 1, the auxiliary gas spray angle Φ2 with respect to the laser scanning direction, the auxiliary gas spray angle Φ3 with respect to the steel plate surface, the rate of fluidity of the auxiliary gas 25 and the amount of particles in the sheet displacement atmosphere were suitably adjusted in the ranges described in the modality to satisfy Condition 6 and Condition 7.
[00164] The verification of the rust resistance was carried out against each of the electrical steel sheets with oriented grain corresponding to the Present Example 9 and Comparative Examples 5 to 7 using the same verification method as the Verification 1 of the resistance to rust . As a result, as illustrated in Table 6, even on a grain oriented electrical steel sheet that does not include the glass film, it was confirmed that the rust resistance of the grain oriented electrical steel sheet was improved when using a configuration that satisfies Condition 6 and Condition 7. [TABLE 6]
[INDUSTRIAL APPLICABILITY]
[00165] According to the aspects of the invention, with respect to the electrical steel sheet with oriented grain in which the groove is formed in the steel sheet surface for the refinement of the magnetic domain, it is possible to make the maximization of the Iron loss reducing effect and minimizing the reduction in magnetic flux density are compatible with each other with a satisfactory balance, and the bending characteristics are also excellent. Consequently, the invention has sufficient industrial applicability. [BRIEF DESCRIPTION OF THE REFERENCE SYMBOLS] 1: GRAIN ORIENTED ELECTRIC STEEL SHEET 2: STEEL SHEET 2a: STEEL SHEET SURFACE 3: GLASS FILM 4: INSULATING FILM 5: GROOVE 5a: FIRST GROOVE SURFACE 5b: SECOND GROOVE SURFACE 5c: GROOVE REGION 5d: GROOVE BOTTOM REGION BL: GROOVE REFERENCE LINE LWC: LONGITUDINAL GROOVE WAVE CURVE SWC: GROOVE CROSS FUNCTION WAVE WAVE CURVE RC RANITY WAVE DOUBLE RAVE: CURVE : GROOVE WIDTH X: LAMINATION DIRECTION Y: PLATE WIDTH DIRECTION Z: PLATE THICKNESS DIRECTION

权利要求:
Claims (4)
[0001]
1. Electric steel sheet with oriented grain (1), characterized in that it comprises: a steel sheet (2) having a steel sheet surface (2a), in which a groove (5), extending in a direction that crosses a rolling direction (X) and whose groove depth direction corresponds to a sheet thickness direction (Z), is formed, where an average groove depth D is greater than 10 μm and equal to or less than 40 µm, in a case where the groove is seen in a cross-section in the groove width direction that is perpendicular to a groove extension direction, when a groove center in the groove width direction is defined as a center of groove width (GC), a deeper portion of the groove deviates from the center of the groove width toward one side in the groove width direction, and a cross-sectional shape of the groove is asymmetrical with respect to the center of the width. of groove as a reference in the direction of the groove width, in a case where the groove is seen in cross-section in the groove width direction, the groove includes a first groove surface (5a) and a second groove surface (5b) as a pair of slanted surfaces that are slanted towards to the deepest portion of the groove of the sheet steel surface, and the center of the groove width is situated on a second side of the groove surface when viewed from the deeper portion; and when an angle, which is formed by a first straight groove end line (Lb1) obtained by linearly approaching the first groove surface and the sheet thickness direction, is defined as a first angle θ1 and an angle, which is formed by a second groove end straight line (Lb2) obtained by linearly approaching the second groove surface and the sheet thickness direction is defined as a second angle θ2, the first angle θ1 and the second angle θ2 satisfy the following Conditional Expressions (1) to (3):
[0002]
2. Grain-oriented electrical steel sheet according to claim 1, characterized in that in the steel sheet, a grain size of a crystal grain that is in contact with the groove is 5 µm or more.
[0003]
3. Grain-oriented electrical steel sheet according to claim 2, characterized in that when the groove is seen in cross-section in the groove width direction, a grain size of a crystal grain, which exists on a lower side of the groove in the sheet steel in the sheet thickness direction, is equal to or greater than 5 μm and equal to or less than the sheet thickness of the sheet steel.
[0004]
4. Grain-oriented electrical steel sheet according to any one of claims 1 to 3, characterized in that when the groove is seen in a longitudinal groove cross-section, including the groove extension direction and the groove direction. sheet thickness, an arithmetic mean height Ra of a roughness curve, which constitutes a contour of a lower groove region, is 1 µm to 3 µm, and an average length of RSm of a roughness curve element, which constitutes the contour of the lower region of the groove, is 10 µm to 150 µm.

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引用文献:

---

公开号 | 申请日 | 公开日 | 申请人 | 专利标题

---

---

DE1804208B1|1968-10-17|1970-11-12|Mannesmann Ag|Process for reducing the watt losses of grain-oriented electrical steel sheets, in particular of cube-texture sheets|

---

JPS572252B2|1978-07-26|1982-01-14|

---

JPH0369968B2|1983-04-20|1991-11-06|Kawasaki Steel Co|

---

JPS6253579B2|1984-11-10|1987-11-11|Nippon Steel Corp|

---

JPS6254873B2|1984-11-10|1987-11-17|Nippon Steel Corp|

---

JPS6253579A|1985-09-03|1987-03-09|Seiko Epson Corp|Portable receiver|

---

JPS6254873A|1985-09-03|1987-03-10|Sanyo Electric Co Ltd|Fixed-head type digital magnetic reproducing device|

---

JPH0772300B2|1985-10-24|1995-08-02|川崎製鉄株式会社|Method for manufacturing low iron loss grain oriented silicon steel sheet|

---

JPS6376819A|1986-09-18|1988-04-07|Kawasaki Steel Corp|Grain-oriented electrical steel sheet having small iron loss and its manufacture|

---

JP2895670B2|1991-10-24|1999-05-24|川崎製鉄株式会社|Grain-oriented electrical steel sheet with low iron loss and method of manufacturing the same|

---

JP2563729B2|1992-08-07|1996-12-18|新日本製鐵株式会社|Method and apparatus for improving iron loss of grain-oriented electrical steel sheet using pulsed CO2 laser|

---

JP3393218B2|1995-08-08|2003-04-07|新日本製鐵株式会社|Manufacturing method of low iron loss unidirectional electrical steel sheet|

---

JP2002292484A|2001-03-30|2002-10-08|Nippon Steel Corp|Device for processing groove using laser|

---

JP2003129138A|2001-10-19|2003-05-08|Nkk Corp|Recycling method for end-of-life vehicle or waste electrical household appliance|

---

JP4189143B2|2001-10-22|2008-12-03|新日本製鐵株式会社|Low iron loss unidirectional electrical steel sheet manufacturing method|

---

JP4846429B2|2005-05-09|2011-12-28|新日本製鐵株式会社|Low iron loss grain-oriented electrical steel sheet and manufacturing method thereof|

---

EP1953249B1|2005-11-01|2018-06-13|Nippon Steel & Sumitomo Metal Corporation|Production method and production system of directional electromagnetic steel plate having excellent magnetic characteristics|

---

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---

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---

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---

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---

RU2763025C1|2021-02-04|2021-12-24|Публичное Акционерное Общество "Новолипецкий металлургический комбинат"|Sheet of anisotropic electrotechnical steel with magnetic loss stabilization and thermally stable laser barriers|

法律状态:
2019-10-08| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2019-10-15| B25D| Requested change of name of applicant approved|Owner name: NIPPON STEEL CORPORATION (JP) |

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2021-06-08| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-07-20| B09W| Decision of grant: rectification|Free format text: REFERENTE A RPI 2631 DE 08/06/2021 |

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2021-08-10| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 19/04/2016, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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JP2015086300|2015-04-20|

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JP2015-086300|2015-04-20|

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PCT/JP2016/062376|WO2016171130A1|2015-04-20|2016-04-19|Oriented magnetic steel plate|

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