Electromagnetic steel sheet, production method for same, laminate, and rotary machine

Abstract

An electromagnetic steel sheet (1) comprises: a base material (11) that is principally Fe and includes 0.1–10.0 mass% of Si, 0.02–4.0 mass% of Mn, 0.001–4.0 mass% of Al, and trace amounts of C, P, S, N, and O; and a crystalline film (12) that is formed on at least a portion of the surface of the base material (11) and has a higher Fe concentration than the base material (11). The average crystal grain size of crystal grains (21) that form the film (12) is no more than 1 / 10 of the average crystal grain size of crystal grains (31) that form the base material (11).

Description

Electrical steel sheet, manufacturing method thereof, laminate and rotating machine

[0001] The present disclosure relates to an electrical steel sheet used primarily as an iron core for a motor, a generator, etc., a method for manufacturing the same, a laminate, and a rotating machine.

[0002] In recent years, amid global trends toward power and energy conservation and global environmental conservation, such as the regulation of chlorofluorocarbons, there has been an increasing demand for energy conservation and higher efficiency in electrical equipment. Accordingly, there has been a growing demand for better magnetic properties in the magnetic steel sheets used in the iron cores of rotating machines, i.e., motor cores. In particular, drive motors for hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs) must be small and high-output, and therefore, there has been a demand for better magnetic properties, i.e., higher magnetic flux density and lower iron loss, in the magnetic steel sheets used as the material for motor cores.

[0003] Iron loss reduction in electrical steel sheets has primarily been achieved by increasing electrical resistivity (i.e., resistivity) through the addition of silicon (Si) or aluminum (Al) to reduce Joule heat loss due to eddy current loss in each sheet of the electrical steel that forms the core during use, or by thinning the sheet thickness. In recent years, a method for reducing iron loss other than increasing resistivity or thinning has been proposed, which involves applying tension to non-oriented electrical steel sheets to improve hysteresis loss. Furthermore, controlling the orientation of crystal grains or nanocrystallizing the steel is considered effective for improving magnetic flux density. Furthermore, suppressing the degradation of magnetic properties due to punching distortion during punching for motor cores and developing materials that minimize degradation of magnetic properties even when compressive stress is applied to the core during assembly are also considered effective. However, no method has been established to achieve both low iron loss and high magnetic flux density in electrical steel sheets, and new material innovations are needed.

[0004] For example, Patent Document 1 discloses a non-oriented electrical steel sheet containing, by mass%, 0.005% or less C (carbon), 1.0% to 7.0% Si, 0.02% to 4.0% Mn (manganese), 0.001% to 4.0% Sol. Al, 0.001% to 0.2% P (phosphorus), 0.005% or less S (sulfur), and 0.005% or less N (nitrogen), with the balance consisting of Fe (iron) and unavoidable impurities. The non-oriented electrical steel sheet has an A layer on both surfaces, which is a region whose lattice constant is 0.002 Å or more larger than the lattice constant at the center of the sheet thickness, and the depth from the surface of the A layer in the sheet thickness direction is 20 μm or less. According to the technology described in Patent Document 1, a non-oriented electrical steel sheet can be provided in which tension is applied to the steel sheet without forming an oxide layer on the steel sheet surface. In other words, a non-oriented electrical steel sheet can be obtained that combines productivity in punching processing with excellent iron loss characteristics. The Sol. Al indicates acid soluble Al.

[0005] Patent Document 2 discloses a soft magnetic Fe-based metal plate having a plurality of crystal orientation layers in the plate thickness direction. Specifically, the soft magnetic Fe-based metal plate described in Patent Document 2 has an αFe phase {222} plane integration degree relative to the plate surface of 55% to 99%, and an average saturation magnetostriction within the plate surface of −0.2×10 -6 The region where the {200} plane integration degree of the α-Fe phase relative to the sheet surface is 25% or more and the {222} plane integration degree of the α-Fe phase is 40% or less is defined as layer A, and the region where the {200} plane integration degree of the α-Fe phase relative to the sheet surface is 25% or more and the {222} plane integration degree of the α-Fe phase is 40% or less is defined as layer B, with layers A and B present in the sheet thickness direction, and layer A present between the sheet surface and layer B that is first observed from the sheet surface toward the sheet surface opposite the sheet surface. According to the technology described in Patent Document 2, it is possible to provide a soft magnetic Fe-based metal sheet that has a high magnetic flux density that cannot be achieved with conventional soft magnetic steel sheets and that suppresses deterioration of magnetic properties even during product manufacturing such as punching and assembly.

[0006] Patent Document 3 discloses a method for manufacturing a non-oriented electrical steel sheet. In the method for manufacturing a non-oriented electrical steel sheet described in Patent Document 3, a slab of steel is prepared, which satisfies, by mass%, 0.1%≦Si≦2.0%, Al≦1.0%, and 0.1%≦Si+2Al≦2.0%, and contains 0.004% or less of C, 0.003% or less of S, 0.003% or less of N, and 0.09% or less of P, with the balance consisting of Fe and unavoidable impurities. In hot rolling, the slab is subjected to rough rolling and subsequent finish hot rolling to obtain a hot-rolled sheet, which is then subjected to pickling and one cold rolling step, and then finish annealing. In the method for producing a non-oriented electrical steel sheet described in Patent Document 3, the slab heating temperature ST, finish hot rolling start temperature FOT, and finish hot rolling finish temperature FT are set to 700° C.≦ST≦1150° C., 650° C.≦FOT≦850° C., and 550° C.≦FT≦800° C., respectively. According to the technology described in Patent Document 3, it is possible to produce a non-oriented electrical steel sheet with a high magnetic flux density at low cost.

[0007] JP 2022-30684 A JP 2016-125106 A JP 2010-1557 A

[0008] However, the non-oriented electrical steel sheet described in Patent Document 1 contains Al, Mn, Sb (antimony), Sn (tin), W (tungsten), and Zn (zinc) as solid solutions in the surface layer. Therefore, even if tension can be applied to the steel sheet without forming an oxide layer, the inclusion of elements other than Fe results in a relative decrease in the Fe content, making it difficult to expect improved magnetic properties. Furthermore, the electrical steel sheet described in Patent Document 2 and the electrical steel sheet manufactured by the manufacturing method described in Patent Document 3 have different textures depending on the layers or regions with different crystal orientations. Furthermore, by undergoing a heat treatment process, high magnetic properties can be obtained and deterioration of the magnetic properties can be suppressed. However, heat treatment promotes grain growth, making it difficult to maintain the fine grains necessary to obtain low iron loss and high magnetic properties. This may prevent the achievement of both low iron loss and high magnetic flux density.

[0009] The present disclosure has been made in view of the above, and has an object to provide an electrical steel sheet that can achieve lower iron loss and higher magnetic flux density than conventional ones.

[0010] In order to solve the above-mentioned problems and achieve the object, the electrical steel sheet according to the present disclosure comprises a base material containing, by mass%, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace elements of C, P, S, N, and O (oxygen), as a main component, Fe, and a crystalline film formed on at least a portion of the surface of the base material, the film having a higher Fe concentration than the Fe concentration of the base material. The average grain size of the crystal grains constituting the film is 1 / 10 or less of the average grain size of the crystal grains constituting the base material.

[0011] The electrical steel sheet according to the present disclosure has the effect of realizing lower iron loss and higher magnetic flux density than conventional ones.

[0012] FIG. 1 is a diagram showing an example of the cross-sectional structure of an electromagnetic steel sheet according to embodiment 1; FIG. 1 is a diagram showing an example of the cross-sectional structure of an electromagnetic steel sheet according to embodiment 2; FIG. 1 is a diagram showing an example of the cross-sectional structure of an electromagnetic steel sheet according to embodiment 3;

[0013] Hereinafter, an electrical steel sheet, a manufacturing method thereof, a laminate, and a rotating machine according to embodiments of the present disclosure will be described in detail with reference to the drawings.

[0014] Embodiment 1. FIG. 1 is a diagram schematically illustrating an example of the cross-sectional structure of an electrical steel sheet according to embodiment 1. Note that "%" indicating the content of each element means mass % unless otherwise specified. The electrical steel sheet 1 according to embodiment 1 includes a substrate 11 containing, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace elements of C, P, S, N, and O, as the main component, Fe; and a crystalline film 12 formed on at least a portion of the surface of the substrate 11 and having a higher Fe concentration than the Fe concentration of the substrate 11. In other words, two types of materials containing Fe as the main component form a layered structure, and the Fe concentration of the material defined as the film 12 is higher than the Fe concentration of the material defined as the substrate 11. This is because the film 12 is made of a material similar to pure iron, while the substrate 11 is made of a material that, in addition to the Fe component, contains, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace components of C, P, S, N, and O. In this way, by forming on the surface the film 12 made of a material that is closer to pure iron with a higher Fe concentration than the substrate 11, which contains almost no elements other than the Fe component, that is, a ferromagnetic material with high saturation magnetization, an electrical steel sheet 1 with high magnetic properties is manufactured.

[0015] Next, a description will be given of the chemical composition of the electrical steel sheet 1 according to embodiment 1. For elements whose concentration varies in the sheet thickness direction, the average value in the sheet thickness direction is taken as the content of this element.

[0016] In the electrical steel sheet 1 according to the first embodiment, Si is an element that is effective in increasing the resistivity of the electrical steel sheet 1 and reducing iron loss, and is therefore added in an amount of 0.1% or more. On the other hand, if Si is added in an amount exceeding 10.0%, the steel becomes significantly embrittled. Therefore, the Si content is set to a range of 0.1% to 10.0%. The Si content is preferably in the range of 1.0% to 6.5%, and more preferably in the range of 1.5% to 4.5%.

[0017] In the electrical steel sheet 1 according to the first embodiment, Mn is added in an amount of 0.02% or more to suppress red shortness during hot rolling. However, if the Mn content exceeds 4.0%, the magnetic flux density decreases and embrittlement becomes significant. Therefore, the Mn content is set to a range of 0.02% or more and 4.0% or less. The Mn content is preferably set to a range of 0.02% or more and 2.0% or less.

[0018] In the electrical steel sheet 1 according to the first embodiment, Al is an element that is effective in increasing the resistivity of the electrical steel sheet 1 and reducing iron loss, and is therefore added in an amount of 0.001% or more. However, if the Al content exceeds 4.0%, embrittlement becomes a problem, as with Si. Therefore, the Al content is set to a range of 0.001% to 4.0%.

[0019] Furthermore, the electrical steel sheet 1 according to the first embodiment contains trace elements of C, P, S, N, and O, but these are present at impurity levels. C is a harmful element that causes magnetic aging and degrades the magnetic properties of the finished steel sheet, so the C content should be 0.005% or less, preferably 0.003% or less. High P content severely embrittles the steel and significantly reduces productivity, so the P content should be 0.2% or less, preferably 0.001% or less. S is a harmful element that generates sulfides such as MnS (manganese sulfide) and increases iron loss, so the S content should be 0.005% or less, preferably 0.003% or less. N is a harmful element that generates nitrides and increases iron loss, so the N content should be 0.005% or less, preferably 0.003% or less. O is a harmful element that generates oxides and deteriorates magnetic properties, so the O content should be 0.005% or less, preferably 0.003% or less.

[0020] Furthermore, in the electrical steel sheet 1 according to the first embodiment, the average grain size of the crystal grains 21 constituting the film 12 is 1 / 10 or less of the average grain size of the crystal grains 31 constituting the substrate 11. The finer the grain size of the crystal grains 21 constituting the film 12, the more the loss due to eddy currents is reduced, and low iron loss is achieved. Therefore, even if the average grain size of the film 12 is 1 / 10 or less of the average grain size of the substrate 11, the effect is obtained, but it is preferably 1 / 100 or less, and more preferably 1 / 1000 or less.

[0021] The average grain size of the crystal grains 31, 21 constituting the substrate 11 and the film 12 of the electrical steel sheet 1 according to the first embodiment is a value measured using images obtained by SEM, transmission electron microscope (TEM), or metallurgical microscope. Within the observed area, not only interphase interfaces and grain boundaries but also all crystal boundaries are observed, and the diameter of the crystalline region surrounded by the crystal boundaries is taken as the crystal grain size. If the crystal boundaries are difficult to see, it is preferable to etch the crystal boundaries using a wet method using a nital solution or a dry etching method. The average grain size is generally measured in a representative area selected within the observed area, containing at least 100 crystal grains 31, 21. Although the number of crystal grains 31, 21 may be smaller, in this case, it is necessary to measure a portion that is statistically sufficiently representative of the entire area. The average grain size is determined by photographing the observation area, defining an appropriate rectangular region on the photograph plane, i.e., the enlarged projection onto the photographed surface of the object, and applying the Jeffries method to the interior of this rectangular region. The Jeffries method is also known as the area measurement method. When observing with an SEM or metallurgical microscope, the crystal boundary width may be too small for the resolution to be observed. In this case, the measured average crystal grain size provides an upper limit for the actual crystal grain size. Specifically, an average crystal grain size measurement of up to 50 μm is acceptable. However, if, for example, there is no clear diffraction peak in X-ray diffraction (XRD) or superparamagnetism is confirmed on the magnetic curve, it is possible that part or all of the magnetic material may be below the lower limit of 1 nm in crystal grain size, then the actual crystal grain size must be determined again by TEM observation.

[0022] The average crystal grain size may be determined using the results of XRD instead of the results of microscopic observation. In this case, the full width at half maximum of the diffraction peak from the (110) plane in the X-ray diffraction pattern obtained from the XRD experiment can be used to determine the average crystal grain size D using the Scherrer equation. The full width at half maximum of the diffraction peak from the (110) plane can be determined by peak resolution using a pseudo-Voigt function for the diffraction pattern. The average crystal grain size D can be determined from the Scherrer equation given by the following equation (1), where B is the full width at half maximum, θ is the Bragg angle, K is the Scherrer constant, and λ is the wavelength of the X-ray. In the first embodiment, however, it is assumed that the X-ray wavelength λ is 0.154 nm and the Scherrer constant K is 0.891. The Bragg angle is half the diffraction angle 2θ.

[0023] D=Kλ / Bcosθ...(1)

[0024] The thickness of the crystalline film 12 in the electrical steel sheet 1 according to embodiment 1 is greater than 0 μm and not more than 10 μm, preferably not more than 7 μm, and more preferably not more than 5 μm. This is because if the thickness is greater than 10 μm, internal stress will be generated between the substrate 11 and the film 12, which will cause peeling between the substrate 11 and the film 12 and will lead to a significant increase in iron loss.

[0025] The film 12 can be formed by allowing the Fe concentration to be higher than that of the substrate 11 and present as a crystalline film 12. Such a film 12 can be formed by a plating method, which will be described later. However, it is not limited to plating, and may also be formed using a film formation method such as a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or a micro spark coating method, or by cladding, welding, or the like. Cladding is a method of bonding two or more different metals together, and welding is a method of integrating two or more base materials using heat, pressure, or both to ensure continuity between the joined base materials. By optimizing the manufacturing conditions for the film 12, as will be described later, it is possible to adjust the crystal grain size of the film 12.

[0026] The electrical steel sheet 1 according to the first embodiment is characterized by having a substrate 11 containing, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace elements of C, P, S, N, and O, as the main component, Fe, and a crystalline film 12 formed on at least a portion of the surface of the substrate 11 and having a higher Fe concentration than the Fe concentration of the substrate 11. The film 12 is also characterized by having crystal grains 21 constituting the film 12 with an average crystal grain size of 1 / 10 or less of the average crystal grain size of crystal grains 31 constituting the substrate 11. In other words, the film 12 has fine crystals with a higher Fe concentration than the Fe concentration of the silicon steel sheet that is the substrate 11, and is formed on the surface of the silicon steel sheet. As a result, compared to conventional techniques, the film 12 does not contain elements other than the Fe component, resulting in improved magnetic properties. Furthermore, since the crystal grains 21 constituting the film 12 are maintained at 1 / 10 or less of the average grain size of the crystal grains 31 constituting the base material 11, it is possible to achieve both low loss and high magnetic flux density. As a result, it is possible to obtain an electrical steel sheet 1 that has lower iron loss and higher magnetic flux density than conventional ones.

[0027] Embodiment 2. Figure 2 is a diagram schematically showing an example of the cross-sectional structure of an electromagnetic steel sheet according to embodiment 2. The electromagnetic steel sheet 1 according to embodiment 2 has a substrate 11 containing, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace components of C, P, S, N, and O, as the main component, Fe, and a crystalline film 12 formed on at least a portion of the surface of the substrate 11 and having a higher Fe concentration than the Fe concentration of the substrate 11. This is the same configuration as embodiment 1.

[0028] Furthermore, in the magnetic steel sheet 1 according to the second embodiment, the film 12 includes multiple crystal grains 21 grown with a crystal orientation different from that of the substrate 11, resulting in a non-oriented film. In other words, the film 12 is composed of crystal grains 21 grown on the substrate 11 with random plane orientations different from that of the substrate 11, resulting in a non-oriented film. Because the crystal grains 21 formed in the film 12 are non-oriented, or in other words, randomly arranged, the polarity of the external magnetization, i.e., the north pole and the south pole, can be switched in a balanced manner. This allows the magnetic steel sheet 1 according to the second embodiment to effectively demonstrate its performance as a motor or generator. In FIG. 2, the hatching of the crystal grains 21 is used to schematically indicate the differences in the crystal orientations of the crystal grains 21. The same applies to FIG. 3. In addition, in this specification, the "crystal orientation" of a crystal grain 21 grown in a certain crystal orientation refers to the orientation of the face of the crystal grain 21 that constitutes a plane parallel to the surface of the film 12 or the surface of the substrate 11 on which the film 12 is formed.

[0029] The orientation or crystal orientation of the crystal grains 31, 21 of the substrate 11 and the film 12 of the electrical steel sheet 1 according to the second embodiment can be investigated by a method using an EBSD apparatus attached to an SEM. This method makes it possible to determine the crystal orientation and crystal system of the crystal grains 31, 21 of the substrate 11 and the film 12. The existence of multiple crystal grains 21 that have grown with a crystal orientation different from that of the substrate 11, such that the film 12 is non-oriented, means that in an inverse pole figure crystal orientation map (IPF MAP) obtained from the measurement results of the EBSD apparatus, which uses an inverse pole figure as a color key and represents the crystal orientation with color, the crystal grains 21 are formed in a color different from that of the crystal grains 31 of the substrate 11, and the crystal grains 21 of the film 12 are not formed in only a specific color; in other words, the crystal grains 21 of the film 12 are formed in a variety of colors.

[0030] The thickness of the crystalline film 12 in the electrical steel sheet 1 according to the second embodiment is 10 μm or less, preferably 7 μm or less, and more preferably 5 μm or less. This is because if the thickness is greater than 10 μm, internal stress will be generated between the substrate 11 and the film 12, which will cause peeling between the substrate 11 and the film 12 and will lead to a significant increase in iron loss.

[0031] The film 12 can be formed by making it exist as a crystalline film 12 with a higher Fe concentration than the Fe concentration of the substrate 11. Such a film 12 can be formed by a plating method described later, but is not limited to plating, and may also be formed using a film formation method such as a CVD method, a PVD method, or an electrical discharge surface treatment method, cladding, welding, or the like.

[0032] The electrical steel sheet 1 according to the second embodiment is characterized by having a substrate 11 containing, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace elements of C, P, S, N, and O, as the main component, Fe, and a crystalline film 12 formed on at least a portion of the surface of the substrate 11. The film 12 is also characterized by having a plurality of crystal grains 21 grown with a crystal orientation different from that of the substrate 11, such that the film 12 is non-oriented. In other words, the film 12 is formed on at least a portion of the surface of the silicon steel sheet, and has non-oriented crystal grains 21 with a higher Fe concentration than the Fe concentration of the silicon steel sheet, which is the substrate 11. As a result, the film 12 does not contain any elements other than the Fe component, resulting in improved magnetic properties compared to conventional techniques. As a result, it is possible to obtain an electrical steel sheet 1 with low iron loss and high magnetic flux density. Furthermore, by making the film 12 a non-oriented film, it is possible to switch the polarity of external magnetization in a well-balanced manner.

[0033] Embodiment 3. Figure 3 is a diagram schematically showing an example of the cross-sectional structure of an electromagnetic steel sheet according to embodiment 3. The electromagnetic steel sheet 1 according to embodiment 3 has a substrate 11 containing, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace components of C, P, S, N, and O, as the main component, Fe, and a crystalline film 12 formed on at least a portion of the surface of the substrate 11 and having a higher Fe concentration than the Fe concentration of the substrate 11. This is the same configuration as embodiments 1 and 2.

[0034] Furthermore, in the electrical steel sheet 1 according to the third embodiment, the film 12 is characterized in that crystal grains 21 grown in two or more different crystal orientations are present, and crystal grains with one orientation are covered by crystal grains grown in another crystal orientation. This structure in which crystal grains grown in one crystal orientation are covered by crystal grains grown in another crystal orientation means that adjacent crystal grains do not have the same crystal orientation, which promotes randomization of orientation and makes the film 12 more likely to be in a non-oriented state.

[0035] 3 shows a plurality of crystal grains 21 having different orientations in the film 12. The crystal grains denoted by the reference numeral 21 indicate crystal grains that make up the film 12, and each crystal grain 21 basically has a different crystal orientation, i.e., has grown in a different crystal orientation. However, crystal grains 21 having the same crystal orientation may exist among them.

[0036] Focus on one crystal grain 211a among these crystal grains 21. This crystal grain 211a has grown in a certain crystal orientation. This crystal grain 211a is surrounded by crystal grains 212a, 212b, 212c, 212d, and 212e that have grown in a crystal orientation different from that of the crystal grain 211a. In this specification, when the crystal grain 211a is surrounded by multiple crystal grains 212a, 212b, 212c, 212d, and 212e that have grown in a crystal orientation different from that of the crystal grain 211a, as in the case of the crystal grain 211a, this is also referred to as the crystal grain 211a being incompletely covered by the crystal grains 212a, 212b, 212c, 212d, and 212e that have grown in a crystal orientation different from that of the crystal grain 211a. The crystal orientations of the crystal grains 212a, 212b, 212c, 212d, and 212e may be different from one another, or may be the same for some of the crystal grains. Focusing on one crystal grain 21b among the crystal grains 21, the crystal grain 211b grown in a certain crystal orientation is covered by a crystal grain 212f grown in a different crystal orientation from the crystal grain 211b. In this specification, when the crystal grain 211b is covered by one crystal grain 212f grown in a different crystal orientation from the crystal grain 211b, as in the case of the crystal grain 211b, this is also referred to as the crystal grain 211b being completely covered by the crystal grain 212f grown in a different crystal orientation from the crystal grain 211b. As described above, the film 12 of the electrical steel sheet 1 according to the third embodiment includes a crystal grain 21 surrounded by crystal grains 21 grown in a certain crystal orientation and crystal grains 21 grown in a different crystal orientation.

[0037] From the perspective of randomizing orientation, it is sufficient to have a structural form in which crystal grains 211a grown in one crystal orientation are covered by crystal grains 212a, 212b, 212c, 212d, and 212e grown in another crystal orientation. However, if the crystal structure is such that crystal grain 211b grown in one crystal orientation is completely covered by crystal grains 212f grown in another crystal orientation, as in crystal grain 21b, magnetic separation occurs and randomization is promoted. In other words, having such a structural form in the electrical steel sheet 1 has the effect of lowering iron loss and increasing magnetic flux density. Furthermore, motors and generators using electrical steel sheet 1 with such a configuration can effectively demonstrate better performance.

[0038] The thickness of the crystalline film 12 in the electrical steel sheet 1 according to the third embodiment is 10 μm or less, preferably 7 μm or less, and more preferably 5 μm or less. This is because if the thickness is greater than 10 μm, internal stress will be generated between the substrate 11 and the film 12, which will cause peeling between the substrate 11 and the film 12 and will lead to a significant increase in iron loss.

[0039] The film 12 can be formed as a crystalline film 12 with a higher Fe concentration than the Fe concentration of the substrate 11. Such a film 12 can be formed by a plating method described later, but is not limited to plating, and may also be formed by a film formation method such as a CVD method, a PVD method, or an electrical discharge surface treatment method, cladding, welding, or the like.

[0040] The electrical steel sheet 1 according to the third embodiment includes a substrate 11 containing, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace elements of C, P, S, N, and O, as the main component, Fe, and a crystalline film 12 formed on at least a portion of the surface of the substrate 11 and having a higher Fe concentration than that of the substrate 11. The film 12 is characterized by having crystal grains 21 grown in two or more different crystal orientations, with crystal grains 211a and 211b grown in one crystal orientation being completely or incompletely covered by crystal grains 212a, 212b, 212c, 212d, 212e, and 212f grown in another crystal orientation. This configuration improves the magnetic properties of the film 12, since it contains no elements other than the Fe component, compared to conventional techniques. As a result, it is possible to obtain an electrical steel sheet 1 with low iron loss and high magnetic flux density.

[0041] Fourth Embodiment In a fourth embodiment, a method for manufacturing the electromagnetic steel sheet 1 described in the first to third embodiments will be described.

[0042] FIG. 4 is a flowchart showing an example of the steps of a method for manufacturing an electromagnetic steel sheet according to a fourth embodiment. In one example, the electromagnetic steel sheet 1 is manufactured by plating the surface of a silicon steel sheet, referred to as a substrate 11, with a material having a higher Fe concentration than the silicon steel sheet to form the film 12. The manufacturing method for the electromagnetic steel sheet 1, which forms the film 12 by plating, includes a degreasing step (step S1) for degreasing the substrate 11, a pickling step (step S2) and an electrolytic cleaning step (step S3) for cleaning the substrate 11, an activation treatment step (step S4) for efficiently performing plating, a plating treatment step (step S5) for forming the film 12 on the substrate 11, a coating step (step S6) for forming an anticorrosive film to suppress rust on the film 12 or an insulating film to ensure the insulating properties of the film 12, and a drying step (step S7). By undergoing these steps, the electromagnetic steel sheet 1 described in the first to third embodiments, particularly the electromagnetic steel sheet 1 described in the second embodiment, can be manufactured. The film 12 formed on the substrate 11 contains a plurality of misoriented crystal grains 21 that have grown in a crystal orientation different from that of the substrate 11. Steps S1 to S3 correspond to a cleaning process. In the cleaning process, it is desirable to perform steps S1 to S3, but any of the steps may be omitted. The plating process in step S5 is an example of a film formation process.

[0043] Each of the steps described above will be explained below. Note that a water washing step is included between steps to wash away any dirt or treatment solution that has adhered to the substrate 11 in the immediately preceding step so as not to carry over to the next step, but this step is omitted here.

[0044] The degreasing process in step S1 is performed to remove oil or oily stains adhering to the surface of the metal, i.e., the substrate 11. This degreasing process is performed by immersing the substrate 11 in a solution of an alkaline compound with a small amount of surfactant added at 50°C for 10 minutes. Examples of alkaline compounds that can be used include sodium hydroxide, sodium carbonate, sodium carbonate hydroxide, sodium orthosilicate, sodium metasilicate, and sodium phosphate. The immersion conditions are merely examples and may be modified as appropriate. The substrate 11 used herein contains, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace amounts of C, P, S, N, and O. The main component is Fe.

[0045] The next step, pickling step S2, is carried out to remove rust or insulating coatings from the substrate 11 before plating, since plating in such a state can cause poor adhesion. The pickling step is carried out by immersing the substrate 11 in hydrochloric acid with a concentration of 10% to 30% by weight at room temperature for 3 minutes. While hydrochloric acid is used here, sulfuric acid or other similar acid may also be used. The immersion conditions may be modified as appropriate.

[0046] The next step S3, the electrolytic cleaning step, is a step of passing an electric current through the substrate 11 as a cathode or an anode to clean the surface of the substrate 11. The electrolytic cleaning step is carried out at 60°C for 1 minute using an alkaline compound as the electrolyte. Examples of alkaline compounds include sodium hydroxide, sodium carbonate, and sodium carbonate hydroxide, and the electrolytic cleaning conditions may be changed as appropriate.

[0047] The next step, the activation treatment step S4, is a step for the purpose of thinly dissolving the substrate 11 together with a thin oxide film or the like present on the surface of the substrate 11 to improve adhesion. In the activation treatment step, the substrate 11 is immersed in hydrochloric acid having a concentration of 10% to 30% by weight at room temperature for 1 minute. The type of acid may be sulfuric acid, but the acid and the conditions may be changed as appropriate.

[0048] The next step, the plating step S5, is a step of plating at least a part of the surface of the substrate 11 using a plating bath containing Fe ions to form a film 12. In the plating step, a plating bath containing iron (II) sulfate, iron (II) chloride, or a mixture thereof is used, the pH of which is in the range of 0.1 to 3.5, preferably 0.5 to 2.5, and the bath temperature is 30° C. to 80° C., preferably 40° C. to 60° C. Furthermore, the current density during electroplating is 0.1 A / dm 2 More than 100A / dm 2 Less than or equal to 0.5 A / dm 2 30A / dm or more 2 The plating process is preferably performed for a time period ranging from 1 minute to 150 minutes, preferably from 5 minutes to 90 minutes. The plating conditions are preferably adjusted so that the thickness of the film 12 is 10 μm or less, preferably 7 μm or less, and more preferably 5 μm or less. This is because if the thickness of the film 12 is greater than 10 μm, internal stress is generated between the substrate 11 and the film 12, which can cause peeling between the substrate 11 and the film 12 and significantly increase iron loss. By performing the plating process while controlling the conditions as described above, it is possible to manufacture an electrical steel sheet 1 as described in embodiment 1, in which the film 12 is formed on at least a portion of the surface of the substrate 11 and contains crystal grains 21 whose average grain size is 1 / 10 or less of the average grain size of the crystal grains 31 constituting the substrate 11. In other words, it is possible to manufacture an electrical steel sheet 1 in which the film 12 having fine crystals with a higher Fe concentration than the Fe concentration of the silicon steel sheet that is the substrate 11 is formed on at least a portion of the surface of the silicon steel sheet.

[0049] As described above, the plating process uses a plating bath made of iron (II) sulfate, iron (II) chloride, or a mixture thereof, and therefore does not contain Si, Mn, or Al as minor components, nor does it contain trace components such as C, P, S, N, and O. In other words, because a plating bath with low impurity elements relative to Fe is used, the film 12 formed by the plating process has a higher Fe concentration than the Fe concentration of the substrate 11, and is close to pure iron with few impurity elements.

[0050] The next step S6, the film formation step, is a step performed for the purpose of inhibiting rust in the formed film 12 or for the purpose of ensuring insulation. In the film formation step, a film formation treatment is performed to form an anti-rust film using an anti-rust agent on the surface of the film 12 of the substrate 11 on which the film 12 has been formed, or an insulating film that ensures the insulating properties of the film 12. In the anti-rust treatment to form an anti-rust film, for example, a water-soluble anti-rust agent is used to form an anti-rust film on the surface of the film 12. In the insulating treatment to form an insulating film, for example, an insulating film such as an organic / inorganic mixed film of phosphate or chromate and an organic resin is formed on the surface of the film 12.

[0051] The final step, the drying step S7, is a step of drying the electromagnetic steel sheet 1 that has been subjected to the coating formation treatment. In the drying step, the electromagnetic steel sheet 1 of the substrate 11 on which the film 12 has been formed is dried by air blowing, and then the electromagnetic steel sheet 1 is dried by holding it in a drying furnace set at a temperature of 50°C to 80°C for a time period ranging from 5 minutes to 60 minutes. This completes the method for manufacturing the electromagnetic steel sheet 1.

[0052] Of the manufacturing conditions in the above manufacturing method, by controlling at least one of the plating conditions in the plating step, namely bath pH, ​​bath temperature, current density, and treatment time, it is possible to manufacture an electrical steel sheet 1 having a film 12 with the characteristic structure described in Embodiments 1 to 3. That is, by controlling the plating conditions, it is possible to manufacture the electrical steel sheet 1 described in Embodiment 1, which includes a substrate 11 containing, by mass %, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace components of C, P, S, N, and O, and whose main component is Fe; and a crystalline film 12 formed on at least a part of the surface of the substrate 11 and having a higher Fe concentration than the Fe concentration of the substrate 11, wherein the average grain size of the crystal grains 21 constituting the film 12 is 1 / 10 or less of the average grain size of the crystal grains 31 of the substrate 11. Moreover, by changing the plating conditions, it is possible to manufacture the electrical steel sheet 1 described in embodiment 2 in which a plurality of crystal grains 21 grown in a crystal orientation different from the orientation of the substrate 11 are present in the film 12 so that the film 12 is non-oriented. Furthermore, it is possible to manufacture the electrical steel sheet 1 described in embodiment 3 in which crystal grains 21 grown in two or more different crystal orientations are present in the film 12, and which has a structure in which crystal grains 211a, 211b grown in one crystal orientation are incompletely or completely covered by crystal grains 212a, 212b, 212c, 212d, 212e, 212f grown in another crystal orientation.

[0053] In the fourth embodiment, an electrical steel sheet 1 can be manufactured by subjecting a substrate 11 whose surface has been cleaned to a plating process, and having, on at least a portion of the surface of the substrate 11, a crystalline film 12 having a crystalline Fe concentration higher than the Fe concentration of the substrate 11, and the film 12 having an average crystal grain size of the crystal grains 21 constituting the film 12 being 1 / 10 or less of the average crystal grain size of the crystal grains 31 constituting the substrate 11. Furthermore, by changing the plating process conditions, an electrical steel sheet 1 can be manufactured having a film 12 formed of a plurality of crystal grains 21 grown in a crystal orientation different from the orientation orientation of the substrate 11, and in which the crystal grains 21 exist in a non-oriented state. Furthermore, by changing the plating conditions, it is possible to manufacture an electrical steel sheet 1 on which a film 12 is formed that has a structure in which crystal grains 21 that have grown in two or more different crystal orientations are present, and crystal grains 211a, 211b that have grown in one crystal orientation are incompletely or completely covered by crystal grains 212a, 212b, 212c, 212d, 212e, 212f that have grown in another crystal orientation.

[0054] Furthermore, because the manufacturing method of the above-described electrical steel sheet 1 does not include a heat treatment step, there is no growth of the crystal grains 21 in the film 12. In other words, the film 12 is formed of fine crystal grains 21, and the size is maintained thereafter, so that an electrical steel sheet 1 that achieves both low loss and high magnetic flux density can be obtained.

[0055] In the above description, an example in which the film 12 is formed by plating has been described, but the film 12 may also be formed by a film formation method such as a CVD method, a PVD method, or a discharge surface treatment method, cladding, welding, etc. That is, in the film formation step of step S5, it is sufficient that a crystalline film 12 having an Fe concentration higher than the Fe concentration of the substrate 11 is formed on at least a part of the surface of the substrate 11 using one of the plating method, the CVD method, the PVD method, the discharge surface treatment method, cladding, and welding.

[0056] Embodiment 5 In embodiment 5, a laminate using the electromagnetic steel sheets 1 according to embodiments 1 to 3 manufactured by the manufacturing method of embodiment 4 will be described. Fig. 5 is a perspective view showing an example of the configuration of the laminate according to embodiment 5. Fig. 5 shows a schematic cross-sectional view of the laminate 100 as viewed from an oblique direction relative to the axial direction.

[0057] The laminate 100 has a structure in which a plurality of disc-shaped electromagnetic steel sheets 1 are stacked in the thickness direction of the electromagnetic steel sheets 1. In this example, the electromagnetic steel sheets 1 that make up the laminate 100 are annular plate-like members and have tooth component portions 5 that protrude toward the center. Specifically, the electromagnetic steel sheets 1 have an annular structure with a circular opening 6 in the center. The annular portion has a plurality of notches 7 that connect to the openings 6. The portions between two adjacent notches 7 form tooth component portions 5. The plurality of electromagnetic steel sheets 1 are stacked with the notches 7 aligned. The laminate 100 formed by stacking a plurality of electromagnetic steel sheets 1 in this manner has a cylindrical structure with a circular opening 106 in the center. The laminate 100 also has teeth 105 formed by overlapping the tooth component portions 5 of each electromagnetic steel sheet 1. In one example, such a laminate 100 is used as a motor core. Note that the configuration of the laminate 100 is not limited to that shown in FIG. 5 , and existing configurations can be adopted. The laminate 100 may also include windings wound around the teeth 105. Examples of winding methods include concentrated winding and distributed winding. By including windings, the laminate 100 can also function as a stator of a motor.

[0058] The electromagnetic steel sheet 1 used in the laminate 100 has a substrate 11 which is a circular plate-shaped member on which the tooth component 5 is provided, and a film 12 described in embodiments 1 to 3 which is formed on two surfaces of the substrate 11 perpendicular to the lamination direction.

[0059] In this way, the laminate 100 according to the fifth embodiment is made by laminating a plurality of the electromagnetic steel sheets 1 described in the first to third embodiments, which have low iron loss and high magnetic flux density, and can contribute to the operation of the stator with low loss and high efficiency.

[0060] Sixth Embodiment In the sixth embodiment, a rotating machine equipped with the laminated body 100 according to the fifth embodiment will be described. Fig. 6 is a cross-sectional view showing an example of the configuration of the rotating machine according to the sixth embodiment. Fig. 6 shows a schematic cross-sectional view perpendicular to the axial direction, which is the rotation axis RA of the rotating machine 130.

[0061] The rotating machine 130 includes a rotor 140 that is rotatable about a rotation axis RA, and an annular stator 150 that is provided coaxially with the rotor 140 and disposed opposite the rotor 140 .

[0062] The rotor 140 includes a rotor core 141 and magnets 143 inserted into magnet insertion holes 142 provided in the rotor core 141 along the circumferential direction of the rotor 140. An example of the magnets 143 is a rare earth sintered magnet. While an example using four magnet insertion holes 142 and four magnets 143 is shown in Figure 6, the number of magnet insertion holes 142 and magnets 143 may be changed depending on the design of the rotor 140.

[0063] The stator 150 includes the laminate 100 described in the fifth embodiment and windings 151 attached to the teeth 105 of the laminate 100. The laminate 100 has openings 106 where the rotor 140 is disposed, and the teeth 105 protrude toward the rotor 140. The windings 151 may be wound in a concentrated or distributed manner. In other words, the stator 150 is formed by the laminate 100 and the windings 151. The rotor 140 is disposed in the openings 106, so that the stator 150 faces the rotor 140. The configuration of the rotating machine 130 is not limited to that shown in FIG. 6 and may be changed depending on the design of the rotor 140 and the laminate 100, or an existing configuration may be adopted.

[0064] In this way, by using the electromagnetic steel sheets 1 of the first to third embodiments, which have low iron loss and high magnetic flux density, the rotating machine 130 according to the sixth embodiment achieves low-loss, highly efficient operation of the stator 150, and can realize a rotating machine 130 that is smaller in size, has higher performance, has lower loss, and is more efficient than conventional rotating machines. Furthermore, it is possible to provide a rotating machine 130 that also contributes to energy savings.

[0065] Hereinafter, the electrical steel sheet 1 of the present disclosure will be described in detail with reference to examples and comparative examples.

[0066] In Examples 1 to 6, the magnetic steel sheet 1 is manufactured by the manufacturing method shown in Embodiment 4. In Comparative Examples 1, 3, and 4, the magnetic steel sheet 1 is manufactured experimentally by a general manufacturing method such as those described in Patent Documents 1 to 3. Comparative Example 2 shows the case where the film 12 is not formed and only the substrate 11 is used.

[0067] In Comparative Example 1, a substrate 11 containing 2.15 wt% Si, 0.25 wt% Mn, and 0.30 wt% Al, with the remainder being Fe, is used, and an electrical steel sheet 1 is manufactured using, as an example, a manufacturing method such as that described in Patent Document 1.

[0068] Comparative Example 2 is an electrical steel sheet 1 constituted only by a substrate 11 containing 2.15 wt % Si, 0.25 wt % Mn, and 0.30 wt % Al, with the remainder being Fe.

[0069] In Comparative Example 3, a substrate 11 containing 2.15 wt% Si, 0.25 wt% Mn, and 0.30 wt% Al, with the remainder being Fe, is used, and an electrical steel sheet 1 is manufactured using, as an example, a manufacturing method such as that described in Patent Document 2.

[0070] In Comparative Example 4, an electromagnetic steel sheet 1 is manufactured using a substrate 11 containing 2.15 wt% Si, 0.25 wt% Mn, and 0.30 wt% Al, with the remainder being Fe, and using, as an example, a manufacturing method such as that described in Patent Document 3.

[0071] In Examples 1 to 6, the magnetic steel sheet 1 is manufactured by forming a film 12 having a higher Fe concentration than the substrate 11, in other words, a film 12 with fewer impurity elements and close to pure iron, on the substrate 11 using the manufacturing method shown in Embodiment 4. Furthermore, by optimizing the manufacturing conditions, more specifically the plating treatment conditions, a film 12 having fine crystal grains 21 and non-oriented crystal grains 21 is formed.

[0072] Table 1 shows the characteristics of the substrate and film of the electrical steel sheet according to the examples and comparative examples, as well as the evaluation results of the properties. The characteristics of the substrate 11 and film 12 of the electrical steel sheet 1 were measured here, including the composition of the substrate 11, the Fe concentration of the film 12 relative to the substrate 11, the size of the crystal grains 21 of the film 12 relative to the substrate 11, the crystal grain size of the film 12 relative to the substrate 11, and whether the crystal grains 21 constituting the film 12 exhibit non-orientation. The characteristics of the electrical steel sheet 1 were measured and evaluated here, including the magnetic flux density and iron loss. "Non-orientation" here refers to the fact that the crystal orientation of the crystal grains 21 in the direction parallel to the surface of the film 12 is random and does not have a specific orientation.

[0073]

[0074] Next, a method for analyzing the Fe concentration of the electrical steel sheet 1 in Examples 1 to 6 and Comparative Examples 1 to 4 will be described. The Fe concentration of the electrical steel sheet 1 is measured, for example, by GD-OES. Here, a Marcus-type high-frequency glow discharge optical emission surface analyzer (manufactured by HORIBA, Ltd., product name: GD-Profiler 2 (registered trademark)) is used as the GD-OES. The surface analysis conditions are a pressure of 600 Pa, an output of 35 W, a frequency of 100 Hz, and a measurement time of 200 seconds. In addition to GD-OES, a field emission-electron probe microanalyzer (FE-EPMA) or the like can also be used, such as element mapping, as long as it produces a clear difference in detection intensity and can analyze the difference in Fe concentration between the substrate 11 and the film 12.

[0075] Next, a method for analyzing the grain size and grain orientation of the electrical steel sheet 1 of Examples 1 to 6 and Comparative Examples 1 to 4 will be described. The grain size and grain orientation of the electrical steel sheet 1 are analyzed by combining an SEM and an EBSD device. Here, the SEM-EBSD device used is a high-resolution FE Schottky scanning electron microscope (manufactured by JEOL Ltd., product name: JSM-7001F) equipped with a crystal orientation analyzer using electron backscatter diffraction (manufactured by TSL Solutions Co., Ltd., product name: EBSD device), software for this analysis (manufactured by TSL Solutions Co., Ltd., product name: OIM6.0), and an energy dispersive X-ray analyzer (manufactured by JEOL Ltd., product name: JED-2300F). The conditions used for the SEM-EBSD analysis are an acceleration voltage of 5.0 kV or more and 15.0 kV or less, a probe current of 2.250 e -008 A or above 2.00e -007 The grain size measured using the EBSD device is expressed as the diameter D of a circle having the same area A as the grain, with the boundary defined as a grain boundary where the specified orientation difference is 5° or more, and is calculated using the following formula (2):

[0076] D = (4A / π) 1 / 2 ....(2)

[0077] Next, a method for evaluating the magnetic properties of the electrical steel sheets 1 of Examples 1 to 6 and Comparative Examples 1 to 4 will be described. The magnetic properties are evaluated by measuring the magnetic hysteresis of a plurality of samples using an AC BH analyzer. The magnetic flux density B of the electrical steel sheets 1 when the frequency is 50 Hz or 60 Hz and the applied magnetic field is 5000 A / m is 50 is obtained, and when the frequency is 50 Hz and the maximum magnetic flux density is 1.5 T, the iron loss W 15 / 50 is measured. In addition to the AC BH analyzer, a DC BH analyzer or BH tracer may also be used as long as these measurement conditions are met. The magnetic properties of each sample are measured by using a search coil to detect the magnetization generated in the electrical steel sheet 1 by the applied magnetic field.

[0078] First, the analysis results for each sample from Examples 1 to 6 and Comparative Examples 1 to 4 will be described. FIG. 7 shows an example of the Fe concentration results obtained by GD-OES from the surface of the electrical steel sheets from Examples 1 to 5. In FIG. 7 , the horizontal axis represents measurement time, and the vertical axis represents Fe concentration. Note that GD-OES measures the light emission generated by plasma-exciting atoms sputtered from the sample surface, so the composition inside the sample is analyzed over time. Therefore, the measurement time on the horizontal axis can also be interpreted as the distance from the surface of the electrical steel sheet 1. For ease of understanding, FIG. 7 clearly shows the film 12 and the substrate 11. Note that the electrical steel sheets 1 from Examples 1 to 6 all exhibit similar results, so FIG. 7 shows a representative example from Examples 1 to 6.

[0079] 7, when the Fe concentrations of the substrate 11 and the film 12 are compared in each sample of Examples 1 to 6, the film 12 has a relatively higher Fe concentration than the substrate 11. From this, it can be said that the film 12 has a higher Fe concentration than the substrate 11 on at least one surface of the substrate 11.

[0080] 8 to 10 are diagrams showing examples of results obtained by analyzing cross sections of the electrical steel sheets according to Examples 1 to 6 using a combination of an SEM and an EBSD device. FIG. 8 shows a grain map, which is a map for identifying crystal grains, and FIGS. 9 and 10 show IPF maps, which are maps in which crystal orientations are colored. However, FIGS. 8 to 10 show color images converted into grayscale. Note that the electrical steel sheets 1 according to Examples 1 to 6 all show similar results, and therefore FIGS. 8 to 10 show representative examples of Examples 1 to 6.

[0081] As shown in the grain map of Figure 8, it can be seen that the film 12 of the electrical steel sheet 1 is a crystalline film and is formed by crystal grains 21 with a fine crystal grain size. It can be confirmed that the crystal grain size of the crystal grains 21 constituting the film 12 is clearly finer than the crystal grain size of the crystal grains 31 constituting the substrate 11. Comparing the crystal grain sizes calculated using equation (2), the average grain size in the substrate 11 is 150 µm, while the average grain size in the film 12 is 10 µm. In other words, it can be confirmed that the average grain size of the crystal grains 21 formed in the film 12 is 1 / 10 or less of the average grain size of the crystal grains 31 formed in the substrate 11.

[0082] As shown in the IPF MAP in Figure 9, it can be seen that the film 12 of the electrical steel sheet 1 is not a film of crystals with a specific orientation, but is a randomly oriented film, in other words, a non-oriented film. Furthermore, it can be seen that the film 12 is formed of a plurality of crystal grains 21 that have grown with a crystal orientation different from that of the substrate 11, that is, the film 12 is a non-oriented film that is unrelated to the orientation of the crystal grains 31 that make up the substrate 11.

[0083] Fig. 10 is an IPF map of an electrical steel sheet 1 manufactured under manufacturing conditions different from those of the example shown in Fig. 9. As shown in the IPF map in Fig. 10, it can be confirmed that the film 12 of the electrical steel sheet 1 contains crystal grains 21 that have grown in two or more different crystal orientations, and that there are also crystal grains 21b in which crystal grains 211b grown in one crystal orientation are completely covered by crystal grains 212f grown in another crystal orientation.

[0084] In the "Fe concentration (relative to substrate)" section of Table 1, samples in which it was confirmed that the film 12 had a higher Fe concentration than the substrate 11 are indicated with a circle, and samples in which this was not confirmed are indicated with a cross. Also, in the "crystal grain size (relative to substrate)" section of Table 1, samples in which it was confirmed that the average grain size of the crystal grains 21 constituting the film 12 was 1 / 10 or less of the average grain size of the crystal grains 31 constituting the substrate 11 are indicated with a circle, and samples in which this was not confirmed are indicated with a cross. Furthermore, in the "crystal grain size of the film relative to the substrate" section of Table 1, the average grain size is listed as a specific numerical value for samples in which the average grain size of the crystal grains 21 constituting the film 12 was 1 / 10 or less of the average grain size of the crystal grains 31 constituting the substrate 11. Furthermore, in the "crystal grains are non-oriented" section of Table 1, samples in which it was confirmed that the crystal grains 21 of the film 12 were non-oriented are indicated with a circle, and samples in which this was not confirmed are indicated with a cross.

[0085] Next, the results of measuring the magnetic properties of each sample in Examples 1 to 6 and Comparative Examples 1 to 4 will be described. Each sample used to measure the magnetic properties was a single plate measuring 150 mm in length and 20 mm in width. The measurement was performed at room temperature, 23°C.

[0086] Magnetic flux density B in each sample according to Examples 1 to 6 and Comparative Examples 1 to 4 50 and iron loss W 15 / 50 The magnetic flux density B of each sample at 23°C is determined by comparing it with Comparative Example 1. 50 and iron loss W 15 / 50 The magnetic flux density B is judged based on whether or not there is a clear difference between the values ​​of B and B in Comparative Example 1. 50 In the case of the magnetic flux density B, since a higher value indicates better characteristics, the judgment is made based on 10% of the value of Comparative Example 1, which is considered to be a clear difference. 50 When the value of the magnetic flux density B is 110% or more of the value of Comparative Example 1, it is judged as "good". 50 If the value of the magnetic flux density B is 90% or less of the value of Comparative Example 1, it is judged as "failure". 50When the value is greater than 90% and less than 110% of the value of Comparative Example 1, it is judged to be "equivalent". 15 / 50 In this case, a lower value leads to a reduction in motor loss and can be said to be a good characteristic, so the judgment is made based on 10% of the value of Comparative Example 1, where a clear difference is considered to be present. 15 / 50 When the value of W is 90% or less of the value of Comparative Example 1, it is judged as "good". 15 / 50 When the value of W is 110% or more of the value of Comparative Example 1, it is judged as "poor". 15 / 50 If the value is greater than 90% and less than 110% of the value of Comparative Example 1, it is judged to be "equivalent." 50 and iron loss W 15 / 50 The results of the evaluation are shown in Table 1.

[0087] In Comparative Example 1, an electrical steel sheet 1 is manufactured using a substrate 11 containing 2.15 wt% Si, 0.25 wt% Mn, and 0.30 wt% Al, with the remainder being Fe, using a manufacturing method such as that described in Patent Document 1. When the Fe concentration of this sample is analyzed according to the above-mentioned method, no significant difference in Fe concentration is confirmed between the substrate 11 and the film 12. Furthermore, when the crystal grain size and crystal orientation are analyzed according to the above-mentioned method, it is not confirmed that the crystal grains 21 of the film 12 do not have a microstructure, and the average crystal grain size of the crystal grains 21 constituting the film 12 is less than 1 / 10 of the average crystal grain size of the crystal grains 31 constituting the substrate 11. Furthermore, it is not confirmed that the orientation of the film 12 is random, i.e., that crystal grains 21 with random crystal orientation are present in the film 12. Furthermore, when the magnetic properties of this sample are evaluated according to the above-mentioned method, the magnetic flux density B 50 is 1.75T, and iron loss W 15 / 50 is 4.25 W / kg. These values ​​of Comparative Example 1 are used as a reference.

[0088] Comparative Example 2 is an electrical steel sheet 1 using only a substrate 11 containing 2.15 wt% Si, 0.25 wt% Mn, and 0.30 wt% Al, with the remainder being Fe. Even when the Fe concentration of this sample is analyzed according to the above-mentioned method, since only the substrate 11 is present, no difference in Fe concentration can be confirmed. Furthermore, even when the crystal grain size and crystal orientation are analyzed according to the above-mentioned method, only the crystal grain size and crystal orientation of the substrate 11 are confirmed, and since the film 12 is not present, no comparative results are obtained. Furthermore, when the magnetic properties of this sample are evaluated according to the above-mentioned method, the magnetic flux density B 50 is "bad", and iron loss W 15 / 50 is "bad." This is a result reflecting the absence of the film 12 that is supposed to improve the magnetic properties.

[0089] In Comparative Example 3, an electrical steel sheet 1 is manufactured using a substrate 11 containing 2.15 wt% Si, 0.25 wt% Mn, and 0.30 wt% Al, with the remainder being Fe, using a manufacturing method such as that described in Patent Document 2. When the Fe concentration of this sample is analyzed according to the above-mentioned method, no significant difference in Fe concentration between the substrate 11 and the film 12 is confirmed. Furthermore, when the crystal grain size and crystal orientation are analyzed according to the above-mentioned method, it is not confirmed that the crystal grains 21 of the film 12 do not have a microstructure, and the average crystal grain size of the crystal grains 21 constituting the film 12 is less than 1 / 10 of the average crystal grain size of the crystal grains 31 constituting the substrate 11. However, it is confirmed that a non-oriented film 12 is formed. Furthermore, when the magnetic properties of this sample are evaluated according to the above-mentioned method, the magnetic flux density B 50 is "good", but iron loss W 15 / 50 is "equivalent." This reflects the fact that although the formation of the non-oriented film 12 contributes to an improvement in magnetic flux density, the absence of the microcrystalline film 12 does not contribute to an improvement in iron loss.

[0090] In Comparative Example 4, an electrical steel sheet 1 is manufactured using a substrate 11 containing 2.15 wt% Si, 0.25 wt% Mn, and 0.30 wt% Al, with the remainder being Fe, using a manufacturing method such as that described in Patent Document 3. When the Fe concentration of this sample is analyzed according to the above-mentioned method, no significant difference in Fe concentration is confirmed between the substrate 11 and the film 12. Furthermore, when the crystal grain size and crystal orientation are analyzed according to the above-mentioned method, it is not confirmed that the crystal grains 21 of the film 12 do not have a microstructure, and the average crystal grain size of the crystal grains 21 constituting the film 12 is 1 / 10 or less of the average crystal grain size of the crystal grains 31 constituting the substrate 11. Furthermore, it is not confirmed that the orientation of the film 12 is random, i.e., that crystal grains 21 with random crystal orientation are present in the film 12. Furthermore, when the magnetic properties of this sample are evaluated according to the above-mentioned method, the magnetic flux density B 50 is "equivalent" and iron loss W 15 / 50 This is a result that reflects the fact that, like Comparative Example 1, the film 12 is neither a film with a high Fe concentration nor a microcrystalline, non-oriented film.

[0091] In Examples 1 to 6, a substrate 11 containing 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace elements of C, P, S, N, and O, as the main component, is used to manufacture an electrical steel sheet 1 having a film 12 formed on at least a portion of the surface of the substrate 11 by the manufacturing method described in Embodiment 4. When the Fe concentration of these samples was analyzed according to the above-described method, it was confirmed that a crystalline film 12 having a higher Fe concentration than the Fe concentration of the substrate 11 was formed. Furthermore, when the crystal grain size and crystal orientation were analyzed according to the above-described method, it was confirmed that the average crystal grain size of the crystal grains 21 constituting the film 12 was 1 / 10 or less of the average crystal grain size of the crystal grains 31 constituting the substrate 11. It was also confirmed that the orientation of the film 12 was random, i.e., that crystal grains 21 with random crystal orientations were present in the film 12. That is, Examples 1 to 6 include a sample that combines Embodiment 1 and Embodiment 2, a sample that combines Embodiment 1 and Embodiment 3, and a sample that combines Embodiment 1, Embodiment 2, and Embodiment 3. Furthermore, when the magnetic properties of these samples were evaluated according to the above-mentioned method, the magnetic flux density B 50 is "good" and iron loss W 15 / 50 is "good". In particular, in Examples 4 to 6, compared to Examples 1 to 3, the crystal grains 21 of the film 12 are finer, being 1 / 100 or less of the average crystal grain size of the crystal grains 31 constituting the substrate 11, and this can be achieved by optimizing the plating treatment conditions described in Embodiment 4. As a result, an effect is achieved in which an electrical steel sheet 1 can be obtained that achieves lower iron loss and higher magnetic flux density than Comparative Example 1.

[0092] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0093] 1 electromagnetic steel sheet, 5 tooth component, 6, 106 opening, 7 notch, 11 substrate, 12 film, 21, 21b, 31, 211a, 211b, 212a, 212b, 212c, 212d, 212e, 212f crystal grains, 100 laminated body, 105 teeth, 130 rotating machine, 140 rotor, 141 rotor core, 142 magnet insertion hole, 143 magnet, 150 stator, 151 winding.

Claims

1. An electrical steel sheet comprising: a substrate containing, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace components of C, P, S, N, and O, and whose main component is Fe; and a crystalline film formed on at least a portion of the surface of the substrate, the film having a higher Fe concentration than the Fe concentration of the substrate, wherein the average grain size of the crystal grains constituting the film is 1 / 10 or less of the average grain size of the crystal grains constituting the substrate.

2. An electrical steel sheet comprising: a substrate containing, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with trace elements of C, P, S, N, and O, and whose main component is Fe; and a crystalline film formed on at least a portion of the surface of the substrate and having a higher Fe concentration than the Fe concentration of the substrate, wherein the film contains a plurality of crystal grains that have grown in a crystal orientation different from that of the substrate, such that the film is non-oriented.

3. An electrical steel sheet according to claim 1, characterized in that the film contains multiple crystal grains that have grown in a crystal orientation different from that of the substrate, such that the film is non-oriented.

4. An electrical steel sheet according to any one of claims 1 to 3, characterized in that the film contains crystal grains grown in two or more different crystal orientations, and crystal grains grown in one crystal orientation are covered by crystal grains grown in another crystal orientation.

5. An electrical steel sheet according to any one of claims 1 to 4, characterized in that the thickness of the film is 10 µm or less.

6. A method for producing an electrical steel sheet according to any one of claims 1 to 5, comprising: a cleaning step of cleaning the surface of the substrate, the substrate containing, by mass, 0.1% to 10.0% Si, 0.02% to 4.0% Mn, and 0.001% to 4.0% Al, with C, P, S, N, and O as trace components, and the main component being Fe; and a film formation step of forming the crystalline film having a higher Fe concentration than the Fe concentration of the substrate on at least a part of the surface of the substrate using one of plating, CVD, PVD, electrical discharge surface treatment, cladding, and welding.

7. A method for manufacturing an electrical steel sheet according to claim 6, characterized in that in the film formation process, the film is formed by plating at least a portion of the surface of the base material using a plating bath containing Fe ions.

8. A method for manufacturing an electrical steel sheet according to claim 6 or 7, further comprising a coating formation step of forming an anti-rust film using an anti-rust agent or an insulating film that ensures the insulating properties of the film on the surface of the film formed on the base material.

9. A laminate comprising a plurality of electromagnetic steel sheets according to any one of claims 1 to 5 stacked together.

10. A rotating machine comprising: a rotor; the laminate according to claim 9, which has openings in the area where the rotor is disposed and has teeth protruding toward the rotor; and a stator, which has windings attached to the teeth and is disposed opposite the rotor.