WO2022255172A1 - 方向性電磁鋼板 - Google Patents
方向性電磁鋼板 Download PDFInfo
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- WO2022255172A1 WO2022255172A1 PCT/JP2022/021301 JP2022021301W WO2022255172A1 WO 2022255172 A1 WO2022255172 A1 WO 2022255172A1 JP 2022021301 W JP2022021301 W JP 2022021301W WO 2022255172 A1 WO2022255172 A1 WO 2022255172A1
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Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1294—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a localized treatment
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
- H01F1/147—Alloys characterised by their composition
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
- H01F1/16—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of sheets
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2201/00—Treatment for obtaining particular effects
- C21D2201/05—Grain orientation
Definitions
- the present invention relates to a grain-oriented electrical steel sheet suitable as a core material for transformers and the like.
- a grain-oriented electrical steel sheet is used, for example, as a core material for a transformer.
- it is necessary to suppress energy loss and noise.
- Such energy loss is affected by the iron loss of the grain-oriented electrical steel sheet, and such noise is affected by the magnetostrictive properties of the grain-oriented electrical steel sheet.
- ing Particularly in recent years, from the viewpoint of energy saving and/or environmental regulations, there is a strong demand for reducing energy loss in transformers and reducing noise during operation of transformers. Therefore, it is extremely important to develop grain-oriented electrical steel sheets with good iron loss and magnetostrictive properties.
- iron loss of a grain-oriented electrical steel sheet is mainly composed of hysteresis loss and eddy current loss.
- Techniques for improving hysteresis loss include highly oriented (110) [001] crystal grains in the rolling direction of the steel sheet, called GOSS orientation, and reducing impurities in the steel sheet.
- GOSS orientation highly oriented (110) [001] crystal grains in the rolling direction of the steel sheet
- impurities there is
- eddy current loss increasing the electrical resistance of steel sheets by adding Si, applying coating tension in the rolling direction of steel sheets, and the like have been developed.
- these methods have limitations in terms of manufacturing.
- Magnetic domain refining technology is being developed as a method of pursuing further reduction in iron loss in grain-oriented electrical steel sheets.
- Magnetic domain refining technology is a technique that introduces non-uniformity in magnetic flux through physical methods such as groove formation and local distortion in steel sheets after finish annealing or insulation coating baking. This is a technique to reduce the iron loss, especially the eddy current loss, of grain-oriented electrical steel sheets by subdividing the width of the 180° magnetic domain (main magnetic domain) formed along the direction.
- Patent Document 1 discloses a technique for improving iron loss from 0.80 W/kg or more to 0.70 W/kg or less by introducing linear grooves having a width of 300 ⁇ m or less and a depth of 100 ⁇ m or less on the steel plate surface. is proposed.
- Patent Document 2 by irradiating a plasma flame in the width direction of the steel plate surface after secondary recrystallization and locally introducing thermal strain, the magnetic flux when excited with a magnetizing force of 800 A / m A method has been proposed to improve iron loss (W17 /50 ) to 0.680 W/kg when a steel plate with a density ( B8 ) of 1.935 T is excited at a maximum magnetic flux density of 1.7 T and a frequency of 50 Hz.
- Patent Document 1 The method of forming linear grooves as described in Patent Document 1 is called heat-resistant magnetic domain refining because the magnetic domain refining effect does not disappear even if strain relief annealing is performed after core molding.
- Patent Document 2 the technique of introducing thermal strain as described in Patent Document 2 is called non-heat-resistant magnetic domain refining because the effect of introducing thermal strain cannot be obtained by strain relief annealing.
- non-heat-resistant magnetic domain refining eddy current loss can be greatly reduced by introducing local strain into the steel sheet.
- non-heat-resistant magnetic domain refining is known to cause deterioration in hysteresis loss and magnetostriction due to the introduction of such strain. Therefore, in order to develop a grain-oriented electrical steel sheet with better iron loss and magnetostrictive properties than before, and furthermore, for the development of transformers with better energy loss and noise properties than before, it is necessary to optimize the closure domain introduction pattern. transformation is required.
- closure domains Since the distribution of closure domains greatly affects the refining ability of non-heat-resistant domains, the introduction pattern of closure domains must be optimized in order to achieve grain-oriented electrical steel sheets with excellent transformer characteristics and both low iron loss and low magnetostriction. It is advantageous to For that purpose, it is necessary to accurately grasp the closure domain. Although many means for measuring the three-dimensional distribution of closure domains have been proposed so far, they all have the following problems.
- Patent Document 3 discloses a method of observing a cross section of a steel sheet sheared along the rolling direction using a Kerr effect microscope.
- the observation surface is distorted due to the mirror polishing that is essential for the preparation of the observation sample, and the magnetic domain structure at the observation point becomes different from the actual one by exposing the cross section.
- the magnetic domain structure at the observation point becomes different from the actual one by exposing the cross section.
- Patent Document 4 discloses a method of estimating the amount of closure domains introduced from the differential waveform of the magnetostriction waveform before and after strain relief annealing, focusing on the time-magnetostriction waveform when excited up to 1.7 T.
- excitation up to 1.7 T includes not only magnetostrictive oscillation due to disappearance of the closure domain, but also magnetostriction oscillation due to the magnetization rotation of the main domain caused by the deviation of the crystal orientation from the rolling direction. It was difficult to estimate the amount of domain introduction.
- the present invention has been made in view of the above circumstances, and has investigated means for optimizing the distribution of closure domains, found means for appropriately using the butterfly curve as described below, and used such means. It is an object of the present invention to provide a grain-oriented electrical steel sheet that is excellent in transformer characteristics and has both low iron loss and low magnetostriction, obtained by
- Non-heat-resistant magnetic domain refining is a technique for controlling magnetic domains by introducing strain into a steel sheet to form a local stress field. Therefore, in order to develop a grain-oriented electrical steel sheet that achieves lower iron loss and noise than conventional ones, the present inventors focused on the stress distribution introduced into the steel sheet and the magnetization direction of the closure domain, and investigated the magnetic properties. investigated the impact on
- an energy beam is applied to the grain-oriented electrical steel sheet in the direction perpendicular to the rolling direction (sheet width direction) to locally introduce thermal strain. Compressive stress in the rolling direction remains.
- crystal grains with the GOSS orientation (110)[001] which is the axis of easy magnetization, are concentrated in the rolling direction.
- a magnetic domain having a magnetization direction (closure magnetic domain) is formed.
- the magnetoelastic effect means that when a tensile stress is applied to a grain-oriented electrical steel sheet, the stress direction becomes energetically stable, and when a compressive stress is applied, the direction orthogonal to the stress becomes energetically stable. This is the phenomenon.
- This closure domain promotes the effect of improving eddy current loss.
- the hysteresis loss increases because the movement of the domain wall due to magnetization is pinned by the strain.
- the anisotropy in the rolling direction when magnetizing the closure domain with magnetization (magnetic moment) in the direction perpendicular to the rolling direction (sheet width direction) in the rolling direction, the anisotropy in the When the anisotropy prevails, the magnetization (magnetic moment) turns to the rolling direction, so that the closure domain disappears.
- a grain-oriented electrical steel sheet deforms so as to extend in the direction of magnetization, so it expands in the rolling direction and contracts in the sheet width direction. After the steel sheet is magnetized until the closure domain disappears, the magnetization in the rolling direction is weakened, that is, when the magnetization is 180° opposite to the originally magnetized direction, the anisotropy in the rolling direction due to magnetization decreases.
- the grain-oriented electrical steel sheet elongates in the sheet width direction and contracts in the rolling direction. That is, under AC magnetization in actual use of a transformer, the magnetization direction of the above degree is reversed according to the frequency, so that the steel sheet repeats elongation and contraction as described above. This is called magnetostrictive vibration, and its amplitude is a small vibration expressed in ⁇ m/m. and released to the outside world. Due to such action, noise is increased due to the existence of closure domains.
- Fig. 1 shows the influence of the magnetic domain on the butterfly curve with the maximum excitation magnetic flux density B of 0 to 1.7 T obtained by observing the magnetic domain in the above investigation.
- the excitation magnetic flux density reaches 1.0T or more
- the closure domain begins to disappear
- the magnetic flux density exceeds 1.5T
- the steel strip elongates due to the closure domain disappearance and contracts due to magnetization rotation. Therefore, it can be seen that the slope of the butterfly curve is beginning to decrease.
- the steel strip elongation ⁇ (hereinafter simply referred to as ⁇ ) when the magnetic flux density B is in the range of 1.0 T to 1.5 T is the closure domain was found to correspond well to the total amount of
- the distribution of the closure domains can be determined from the value of ⁇ , the length of the closure domain observed from the steel sheet surface in the rolling direction (the width of the closure domain), and the interval between the closure domains introduced into the steel sheet (the number of closure domains). can be estimated very accurately. Then, based on this estimation, by controlling the closure domain width and the number of closure domains within appropriate ranges, it is possible to manufacture a grain-oriented electrical steel sheet that achieves both lower core loss and lower noise characteristics than conventional ones. was found to be possible.
- the laser having a Gaussian profile is a laser whose intensity distribution (profile) obtained by scanning the laser in a certain direction with respect to a profiler having a linear slit is a Gaussian distribution.
- a magnetostrictive vibration waveform was measured using a laser Doppler magnetostrictive vibrometer to measure the magnetostrictive vibration waveform when magnetized with a sinusoidal AC magnetization of 1.5 T and 50 Hz to obtain a butterfly curve. rice field. Furthermore, using a commercially available magnet viewer, the magnetic domain pattern on the surface of the steel sheet was transferred, and the width of the closure magnetic domain formed across the rolling direction was measured.
- a three-phase stacked transformer (iron core weight: 500 kg) was manufactured. Iron loss properties were measured. The iron loss characteristics at 1.7T, 50Hz were measured using a wattmeter. At the same time, this model transformer was excited in a soundproof room under the conditions of maximum magnetic flux density Bm: 1.7 T and frequency: 50 Hz, and the noise level (dBA) was measured using a sound level meter.
- FIG. 3 shows the relationship between ⁇ and the closure domain width and the core loss W 17/50
- FIG. 4 shows the relationship between ⁇ and the closure domain width and the transformer noise level.
- ⁇ is in the range of 0.010 ⁇ 10 ⁇ 6 or more and 0.200 ⁇ 10 ⁇ 6 or less and the closure domain width is in the range of 50 ⁇ m or more and 240 ⁇ m or less, a particularly high iron loss improvement effect can be confirmed.
- ⁇ is in the range of 0.010 ⁇ 10 -6 or more and 0.200 ⁇ 10 -6 or less and the closure domain width is in the range of 50 ⁇ m or more and 240 ⁇ m or less, it was found that a more excellent iron loss improvement effect is exhibited. rice field.
- a sample was prepared by linearly irradiating a laser beam having the above profile in the width direction while varying the irradiation interval in the rolling direction from 1 to 12 mm.
- a part of the steel strip of the grain-oriented electrical steel sheet thus obtained is cut out, and magnetostrictive vibration waveform is measured when magnetized with a sine wave AC magnetization of 1.5 T and 50 Hz using a laser Doppler magnetostrictive vibrometer, and a butterfly curve is obtained. Obtained.
- the magnetic domain pattern on the surface of the steel sheet was transferred, and the width of the closure domain formed across the rolling direction was measured.
- a 3-phase transformer (iron core mass: 500 kg) is manufactured using the grain-oriented electrical steel sheet sample that has undergone magnetic domain refining, and the magnetic flux density of the iron core legs is 1.7 T at a frequency of 50 Hz.
- the iron loss characteristics at the time were measured.
- This iron loss characteristic at 1.7T, 50Hz was measured by using a wattmeter.
- FIG. 5 shows the relationship between the closure domain formation interval and the iron loss W 17/50
- FIG. 6 shows the relationship between the closure domain formation interval and the transformer noise level. From FIG. 5, it can be confirmed that the core loss is improved more preferably in the range of the closure domain formation interval of 3 mm or more and 10 mm or less. Further, from FIG. 6, it was confirmed that the noise deteriorated as the interval between the closure domains narrowed. Especially when it is less than 3 mm, the noise becomes louder. As described above, the present inventors have found that when the interval between closure domains is 3 mm or more and 10 mm or less, both the effects of lower core loss and lower noise are exhibited.
- FIG. 10 is a diagram showing the influence of magnetic domains on butterfly curves when the maximum excitation magnetic flux density B is in the range of 0 to 1.7T.
- FIG. 4 is a schematic diagram showing an example of a suitable beam profile to which an aperture is applied;
- FIG. 4 is a diagram showing the relationship between ⁇ , closure domain width, and iron loss W 17/50 .
- FIG. 3 is a diagram showing the relationship between ⁇ , closure domain width, and transformer noise level;
- FIG. 4 is a diagram showing the relationship between the formation interval of closure domains and iron loss W 17/50 .
- FIG. 4 is a diagram showing the relationship between the formation interval of closure domains and the noise level of the transformer;
- FIG. 4 is a schematic diagram showing an example of a suitable beam profile to which a slit is applied;
- the present invention is not limited to the configuration disclosed in this embodiment, and can be modified in various ways without departing from the gist of the present invention.
- the steel strip elongation amount ( ⁇ ) is 0.010 ⁇ 10 -6 when the magnetic flux density B is in the range of 1.0 to 1.5 T.
- the length of the closure domain in the rolling direction (closure domain width) is 20 ⁇ m or more and 240 ⁇ m or less] If the ⁇ is less than 0.010 ⁇ 10 ⁇ 6 , the strain introduced is too small, so that the magnetic domain refining effect does not appear. On the other hand, if the ⁇ exceeds 0.240 ⁇ 10 ⁇ 6 , the introduced strain becomes excessive and deteriorates the hysteresis loss.
- the closure domain width exceeds 240 ⁇ m
- the depth of the closure domain in the plate thickness direction becomes insufficient, so that the domain refining effect is reduced.
- the closure domain width is less than 20 ⁇ m
- the closure domain is too thin in the rolling direction, so that the magnetization does not become discontinuous and the magnetic domain refining effect is reduced.
- ⁇ exceeds 0.240 ⁇ 10 ⁇ 6
- noise suddenly increases. This is thought to be because ⁇ corresponds to the total amount of closure domains and generation and disappearance of closure domains occurs.
- ⁇ is set in the range of 0.010 ⁇ 10 ⁇ 6 to 0.240 ⁇ 10 ⁇ 6 and the closure domain width is set in the range of 20 ⁇ m to 240 ⁇ m. Within this range, an excellent low core loss effect and low noise effect can be obtained.
- ⁇ is 0.010 ⁇ 10 ⁇ 6 or more and 0.200 ⁇ 10 ⁇ 6 or less and the closure domain width is 50 ⁇ m or more and 240 ⁇ m or less, particularly excellent iron loss characteristics can be exhibited, which is preferable. More preferably, ⁇ is 0.100 ⁇ 10 ⁇ 6 or more and 0.200 ⁇ 10 ⁇ 6 or less, and the closure domain width is 50 ⁇ m or more and 240 ⁇ m or less.
- the formation interval of closure domains is 3 mm or more and 10 mm or less. If the spacing between the closure domains is less than 3 mm, the total amount of closure domains increases, possibly deteriorating the hysteresis loss. On the other hand, if the formation interval is more than 10 mm, the total amount of closed loop domains to be introduced decreases, and the magnetic domain refining ability tends to decrease. Further, when the formation interval of the closure domains is less than 3 mm, the noise tends to increase, probably because the total amount of closure domains increases. Therefore, when the formation interval of the closure domains is set to 3 mm or more and 10 mm or less, it is possible to obtain both the effects of lower core loss and lower noise.
- the formation interval of the closure domains means the irradiation interval in the rolling direction of the energy beams irradiated during the non-heat-resistant magnetic domain refining treatment.
- the chemical composition of the slab which is the raw material of the grain-oriented electrical steel sheet of the present invention, may be any composition as long as it causes secondary recrystallization.
- an inhibitor for example, when using an AlN-based inhibitor, Al and N are used, and when using an MnS/MnSe-based inhibitor, appropriate amounts of Mn and Se and/or S are added. Just do it. Of course, both inhibitors may be used together.
- the preferred contents of Al, N, S and Se when using the above inhibitor are Al: 0.010 to 0.065% by mass, N: 0.0050 to 0.0120% by mass, S: 0.005-0.030% by mass and Se: 0.005-0.030% by mass is.
- the present invention can also be applied to grain-oriented electrical steel sheets with limited Al, N, S, and Se contents and no inhibitors.
- the contents of Al, N, S and Se are respectively Al: less than 0.010% by mass, N: less than 0.0050% by mass, It is preferable to suppress S: less than 0.0050% by mass and Se: less than 0.0050% by mass.
- C 0.08% by mass or less C is added to improve the structure of the hot-rolled sheet.
- the C content is desirably 0.08% by mass or less because it becomes difficult to char.
- C may be 0% by mass.
- Si 2.0-8.0% by mass
- Si is an element effective in increasing the electric resistance of steel and improving iron loss.
- the content is preferably 2.0% by mass or more.
- the Si content be 8.0% by mass or less. More preferably, the lower limit is 2.5% by mass and the upper limit is 7.0% by mass.
- Mn 0.005-1.0% by mass
- Mn is an element necessary for improving hot workability.
- the content is preferably 0.005% by mass or more.
- the Mn content is preferably 1.0% by mass or less. More preferably, the lower limit is 0.01% by mass and the upper limit is 0.9% by mass.
- Ni 0.03 to 1.50% by mass
- Sn 0.01 to 1.50% by mass
- Sb 0.005 to 1.50% by mass
- Cu 0.03 to 3.0% by mass
- P 0.03 to 0.50% by mass
- Ni is an element effective for improving the structure of the hot-rolled sheet and improving the magnetic properties. If the Ni content is less than 0.03% by mass, the contribution to magnetic properties is small. On the other hand, if it exceeds 1.50% by mass, the secondary recrystallization becomes unstable and the magnetic properties deteriorate. Therefore, the Ni content is preferably in the range of 0.03 to 1.50% by mass.
- Sn, Sb, Cu, P, Mo and Cr which are other optional components, are also elements that improve the magnetic properties like Ni.
- the content is less than the above lower limit, the effect is not sufficient, and if the content exceeds the above upper limit, the growth of secondary recrystallized grains is suppressed, resulting in deterioration of magnetic properties. Therefore, it is preferable to set the respective contents within the above ranges.
- the balance other than the above components is Fe and unavoidable impurities.
- C is decarburized in the primary recrystallization annealing, and Al, N, S and Se are purified in the secondary recrystallization annealing.
- Al, N, S and Se are purified in the secondary recrystallization annealing.
- the contents of these components are reduced to the level of unavoidable impurities.
- the grain-oriented electrical steel sheet of the present invention can be manufactured, as an example, by the following procedure (excluding the magnetic domain refining step). That is, a steel material (slab) for a grain-oriented electrical steel sheet having the above composition system is subjected to hot rolling and, if necessary, hot-rolled sheet annealing. Then, the steel strip is finished to the final thickness by cold rolling once or twice or more with intermediate annealing. Thereafter, the steel strip is decarburized and annealed, coated with an annealing separator containing MgO as a main component, wound into a coil, and subjected to final annealing for the purpose of secondary recrystallization and formation of a forsterite coating. apply.
- the steel strip after such finish annealing is subjected to flattening annealing, and then subjected to insulating film baking, for example, forming a magnesium phosphate-based tension film to form a product plate (grain-oriented electrical steel sheet (excluding the magnetic domain refining step)). do.
- the product sheet obtained as described above is subjected to non-heat-resistant magnetic domain refining to obtain the grain-oriented electrical steel sheet of the present invention (magnetic domain refining step).
- magnetic domain refining step non-heat-resistant magnetic domain refining used in the magnetic domain refining step in the present invention will be described.
- Irradiation method of energy beam In the present invention, a beam having a Gaussian-shaped beam profile is used as the energy beam to irradiate the steel sheet to introduce thermal strain, thereby controlling the total amount of closure domains and precisely defining ⁇ . can be kept within the range.
- ⁇ can be remarkably kept within the specified range by irradiating a cut beam of energy below a certain level through a slit having an opening in the rolling direction before entering the steel plate.
- "before incidence on the steel plate” means an arbitrary coordinate in the energy beam optical path between the energy beam source and the steel plate.
- cutting a beam with energy below a certain level means that a beam in an area with an energy intensity below a certain level, such as 40% or less of the maximum peak intensity, does not enter the steel sheet.
- the upper limit of the energy intensity of the beam to be cut is 50% of the maximum peak intensity.
- the energy beam is not particularly limited as long as it can be generally used for non-heat-resistant magnetic domain refining treatment, and for example, an electron beam, a laser beam, a plasma flame, or the like can be used.
- ⁇ Beam irradiation method for obtaining better characteristics As a method for obtaining even higher low iron loss and low magnetostriction effects, there is a method of installing a circular diaphragm (aperture) on the beam path.
- an aperture is provided between the beam generation source and the beam deflection system, and the steel plate is irradiated with the beam obtained by cutting the beam whose intensity is below a certain level, as described above.
- Irradiation Direction of Energy Beam In the present invention, linear distortion is performed by irradiation with an energy beam such as an electron beam, laser, or plasma flame.
- an energy beam such as an electron beam, laser, or plasma flame.
- linear strain is introduced while irradiating beams so as to intersect the rolling direction.
- the scanning direction of the beam is preferably in the range of 60° to 120° from the rolling direction, more preferably 90°, that is, scanning along the sheet width direction. This is because when the deviation from the sheet width direction increases, the amount of strain introduced into the steel sheet increases, leading to deterioration of magnetostriction.
- “linear” may be a solid line, a dotted line, or a dashed line.
- the energy beam irradiation interval (interval between adjacent thermally distorted regions) is preferably in the range of 3 mm or more and 10 mm or less because closure domains are formed at the energy beam irradiation locations.
- Beam output 30 W or more and 10 kW or less
- the preferable range of the beam output is 30 W or more and 10 kW or less. More preferably, the lower limit is about 50W and the upper limit is about 8kW.
- the acceleration voltage is preferably 60 kV or more and 300 kV or less
- the beam current is preferably 0.5 to 40 mA.
- ⁇ Laser output 20 W or more and 500 W or less
- the laser output is preferably smaller than the beam output from the viewpoint of the amount of strain introduced. This is because when the laser output is increased, an excessive amount of strain is introduced, and the hysteresis loss is deteriorated more than the eddy current loss is improved, and noise is further deteriorated. Therefore, the laser output is preferably 500 W or less. On the other hand, if the laser power is too low, there will be insufficient energy to create the strain. Therefore, the laser output is preferably 20 W or more.
- the spot diameter of an energy beam such as an electron beam or laser is preferably 300 ⁇ m or less. It is more preferably 280 ⁇ m or less, still more preferably 260 ⁇ m or less.
- the spot diameter refers to the full width at half maximum of a beam profile obtained by a slit method using a slit with a width of 30 ⁇ m.
- the degree of vacuum in the beam irradiation region is high, and the pressure is preferably 3 Pa or less. There is no particular lower limit, but if it is excessively lowered, the cost of vacuum systems such as vacuum pumps will increase. Therefore, it is preferable to set the pressure to 10 ⁇ 5 Pa or higher for practical use. Note that laser processing is possible in the air, so this is not the case.
- Closure Domain Width The width of the closure domain formed on the surface of the steel sheet can be measured by acquiring the magnetic domain pattern on the surface of the steel sheet using a commercially available domain viewer such as MV-95 manufactured by Sigma High Chemical.
- an aperture having a hole diameter 20% smaller than the total length of the laser spot at that point was placed just before the laser converging lens, and a laser with a profile as shown in FIG. 2 was also prepared.
- Magnetic domain refining treatment was performed by linearly irradiating the steel sheet with only one of the lasers.
- the laser irradiation interval (closure domain formation interval) was set to 1 mm, 3 mm, 8 mm, 10 mm, or 12 mm.
- a part of the thus-obtained grain-oriented electrical steel strip was cut out, and a magnetostrictive vibration waveform was measured using a laser Doppler magnetostrictive vibrometer to measure the magnetostrictive vibration waveform when magnetized with a sinusoidal AC magnetization of 1.5 T and 50 Hz to obtain a butterfly curve. rice field. Furthermore, using a commercially available magnet viewer, the magnetic domain pattern on the surface of the steel sheet was transferred, and the width of the closure magnetic domain formed across the rolling direction was measured.
- a three-phase transformer (with a core weight of 500 kg) is manufactured. was measured. This iron loss characteristic at 1.7T, 50Hz was measured by using a wattmeter. At the same time, this model transformer was excited in a soundproof room with a maximum magnetic flux density Bm of 1.7 T and a frequency of 50 Hz, and the noise level (dBA) was measured using a sound level meter.
- Table 2 shows the results of the above examples. From the table, the grain-oriented electrical steel sheet having a ⁇ within the range of the present invention of 0.010 ⁇ 10 -6 or more and 0.240 ⁇ 10 -6 or less and a closure domain width of 20 ⁇ m or more and 240 ⁇ m or less is higher than the comparative example. It can be seen that a low core loss (W 17/50 ⁇ 0.73 W/kg) and a low noise effect can be obtained.
- ⁇ was 0.010 ⁇ 10 ⁇ 6 or more and 0.200 ⁇ 10 ⁇ 6 or less, and the closure domain width was 50 ⁇ m or more and 240 ⁇ m.
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Abstract
Description
とりわけ近年では、省エネ及び/又は環境規制の観点から、変圧器におけるエネルギー損失、及び、変圧器の動作時における騒音の低減が強く求められている。そのため、鉄損及び磁歪特性の良好な方向性電磁鋼板を開発することが、極めて重要となっている。
しかしながら、方向性電磁鋼板の更なる低鉄損化を追求する際には、これらの手法では製造上の限界がある。
したがって、従来よりも鉄損及び磁歪特性に優れた方向性電磁鋼板の開発のため、ひいては、従来よりもエネルギー損失及び騒音特性に優れた変圧器の開発のためには、還流磁区導入パターンの最適化が求められている。
非耐熱型磁区細分化は、鋼板に歪みを導入して、局所的な応力場を形成することで、磁区を制御する技術である。そこで、本発明者らは、従来よりも低鉄損かつ低騒音を実現する方向性電磁鋼板を開発するために、鋼板に導入される応力分布と還流磁区の磁化方向に着目して、磁気特性への影響を調査した。
方向性電磁鋼板は、磁化容易軸となるGOSS方位(110)[001]を持つ結晶粒が圧延方向に集積しているため、圧延方向に圧縮応力が働くと、磁気弾性効果によって板幅方向に磁化方向を持つ磁区(還流磁区)が形成される。なお、磁気弾性効果とは、方向性電磁鋼板に引張応力を加えると、その応力方向がエネルギー的に安定になり、圧縮応力を加えると、その応力と直交する方向がエネルギー的に安定になる、という現象である。
すなわち、変圧器の実使用上の交流磁化下では、上述程度の磁化の方向が周波数に応じて逆転するため、上述したように鋼板が伸長収縮を繰り返すことになる。これを磁歪振動と呼び、その振幅はμm/mで表されるような小さな振動であるものの、方向性電磁鋼板を変圧器の鉄心とした際には、この磁歪振動が伝播することで、騒音となって外界に放出される。このような作用があるため、還流磁区の存在によって騒音が大きくなるのである。
上記調査のうち、磁区観察を行って得られた最大励磁磁束密度Bが0~1.7Tのバタフライカーブにおける磁区の影響を図1に示す。図1に見られるように、励磁磁束密度が1.0T以上になると還流磁区の消滅が始まり、磁束密度が1.5Tを超えると還流磁区の消失による鋼板の伸長に、磁化回転による鋼板の収縮が重なっているため、バタフライカーブの傾きが減少し始めていることが分かる。すなわち、最大励磁磁束密度Bが1.5T以上の磁束密度―磁歪波形(バタフライカーブ)において、磁束密度Bが1.0Tから1.5Tの範囲の鋼板伸長量Δλ(以下、単にΔλと示す)が還流磁区の総量によく対応することを知見した。
(実験1)
まず、図2に示すような、最大強度に対して一定以下のエネルギー強度を有する領域のビームをカットすることにより急峻なエネルギー分布に整えたプロファイルを有するレーザー照射を行って磁区細分化処理を行った。
なお、レーザーの照射条件は、既知の方法で製造された板厚0.23mmの方向性電磁鋼板の鋼帯に対して、ガウシアン形状のプロファイルを持つレーザーを、出力を様々に変えて照射した。このとき、レーザーはビーム径(=半値全幅)が20μm、100μm、又は200μmのものを使用し、レーザーを収束させるレンズの直前(収束レンズからの距離:20mm)に、孔径が8mm、10mm、又は12mmのアパーチャを通して、上記図2に記載のプロファイルとし、その照射間隔を5mmとした。また、最大強度値の30%以下のエネルギーとなるビームをカットしたビームを照射した。
なお、本発明におけるガウシアン形状のプロファイルを持つレーザーとは、直線状のスリットを持つプロファイラに対して、ある方向にレーザーを走査して得られる強度分布(プロファイル)が、ガウシアン分布となるようなレーザーを指す。
かくして得られた方向性電磁鋼板の鋼帯から一部を切り出し、レーザードップラー式の磁歪振動計を用いて1.5T,50Hzの正弦波交流磁化したときの磁歪振動波形を測定し、バタフライカーブを得た。
さらに市販のマグネットビューワーを用いて、鋼板表面の磁区パターンを転写し、圧延方向を横切るように形成された還流磁区の幅を測定した。
図3に見られるように、Δλが0.010×10-6以上0.240×10-6以下の範囲にあり、かつ、還流磁区幅が20μm以上240μm以下の範囲であれば、高い鉄損改善効果が確認できる。また、Δλが0.010×10-6以上0.200×10-6以下の範囲にあり、かつ、還流磁区幅が50μm以上240μm以下の範囲にあるとき、特に高い鉄損改善効果が確認できる。
以上の実験結果から、上記Δλが0.010×10-6以上0.240×10-6以下であり、かつ上記還流磁区幅が20μm以上240μm以下であるときに、高い低鉄損及び低騒音効果が得られるとの知見を得た。特に、Δλが0.010×10-6以上0.200×10-6以下の範囲にあり、かつ、還流磁区幅が50μm以上240μm以下の範囲にあるとき、より優れた鉄損改善効果を発現することを見出した。
続いて還流磁区の形成間隔の適正な範囲について調査を行った。
既知の方法で製造された板厚0.23mmの方向性電磁鋼板の鋼帯に対して、ガウシアン形状のプロファイルを持つレーザーを、Δλが0.100×10-6となるように出力を調整して板幅方向に線状に照射して、試料を作製した。その際、レーザーは、ビーム径(=半値全幅)が100μmのものを使用し、収束レンズに入射する直前位置(鋼板からの距離:20mm)に配置した孔径が10mmのアパーチャを通し最大強度値の30%以下のエネルギーとなるビームをカットして、図2に記載されたプロファイルとした。圧延方向の照射間隔を1~12mmに変化させて該プロファイルを有するレーザービームを板幅方向に線状に照射し試料を作製した。
かくして得られた方向性電磁鋼板の鋼帯から一部を切り出し、レーザードップラー式の磁歪振動計を用いて1.5T,50Hzの正弦波交流磁化したときの磁歪振動波形を測定して、バタフライカーブを得た。
さらに市販のマグネットビューワーを用いて、鋼板表面の磁区パターンを転写し、圧延方向を横切るように形成された還流磁区の幅を測定したところ、還流磁区幅は120μmであった。
図5より、還流磁区の形成間隔が3mm以上10mm以下の範囲において、より好適な鉄損改善が確認できる。
また、図6より、還流磁区の形成間隔が狭まるほど騒音が劣化する傾向が確認できた。特に3mm未満になると、騒音がより大きくなる。
以上のとおり、還流磁区の形成間隔が3mm以上10mm以下の場合に、より高い低鉄損化と低騒音化の効果を併せて発現することを知見した。
1.圧延方向を横切る方向に線状に熱歪み領域を有し、かかる熱歪み領域内に還流磁区を備える方向性電磁鋼板であって、前記方向性電磁鋼板を1.5T以上に励磁したときの磁束密度B―磁歪波形λ(バタフライカーブ)において、磁束密度Bが1.0~1.5Tの範囲の鋼板伸長量(Δλ)が0.010×10-6以上0.240×10-6以下であり、かつ前記還流磁区の圧延方向長さ(還流磁区幅)が20μm以上240μm以下であることを特徴とする方向性電磁鋼板。
ただし、本発明は、本実施形態に開示の構成のみに限定されることなく本発明の趣旨を逸脱しない範囲で種々の変更が可能である。
[方向性電磁鋼板を1.5T以上に励磁したときの磁束密度B―磁歪波形λ(バタフライカーブ)において、磁束密度Bが1.0~1.5Tの範囲の鋼板伸長量(Δλ)が0.010×10-6以上0.240×10-6以下であり、かつ前記還流磁区の圧延方向長さ(還流磁区幅)が20μm以上240μm以下]
上記Δλが0.010×10-6未満の場合には、導入された歪みが過少であるため、磁区細分化効果が発現しない。一方、上記Δλが0.240×10-6を超えると、導入された歪みが過剰となって、ヒステリシス損を劣化させる。
さらに、Δλは0.240×10-6を超えると急激に騒音が大きくなる。これはΔλが還流磁区の総量に対応し、還流磁区の生成消滅が生じるためと考えられる。
よって、本発明では、前記Δλを0.010×10-6以上0.240×10-6以下の範囲とし、かつ還流磁区幅を20μm以上240μm以下とする。この範囲内であれば、優れた低鉄損効果及び低騒音効果を得ることができる。Δλが0.010×10-6以上0.200×10-6以下であり、かつ還流磁区幅が50μm以上240μm以下である時には特に優れた鉄損特性を発現できるため、好ましい。より好ましくは、Δλが0.100×10-6以上0.200×10-6以下であり、かつ還流磁区幅が50μm以上240μm以下である。
還流磁区の形成間隔が3mm未満の場合、還流磁区の総量が増加して、ヒステリシス損が劣化する畏れがある。一方、形成間隔が10mm超の場合、導入する還流磁区の総量の減少によって、磁区細分化能力が低下しやすくなる。
また、還流磁区の形成間隔が3mm未満になると、騒音が大きくなりやすいのは、還流磁区の総量が増加するためと考えられる。
よって、還流磁区の形成間隔を3mm以上10mm以下とすると、より高い低鉄損化と低騒音化の効果を併せて得ることができる。
なお、還流磁区の形成間隔とは、非耐熱型磁区細分化処理の際に照射されるエネルギービームの圧延方向の照射間隔を意味する。
本発明の方向性電磁鋼板の素材となるスラブの成分組成は、二次再結晶が生じる成分組成であればよい。また、インヒビターを利用する場合、例えばAlN系インヒビターを利用する場合であればAlおよびNを、またMnS・MnSe系インヒビターを利用する場合であれば、MnとSe及び/またはSを適量含有させればよい。もちろん両インヒビターを併用してもよい。
上記インヒビターを利用する場合における、Al、N、S及びSeの好適含有量はそれぞれ、
Al:0.010~0.065質量%、
N:0.0050~0.0120質量%、
S:0.005~0.030質量%および
Se:0.005~0.030質量%
である。
Al:0.010質量%未満、
N:0.0050質量%未満、
S:0.0050質量%未満および
Se:0.0050質量%未満
に抑制することが好ましい。
C:0.08質量%以下
Cは、熱延板組織の改善のために添加をするが、Cの含有量が0.08質量%を超えると、磁気時効の起こらない50質量ppm以下まで製造工程中に脱炭することが難しくなるため、C含有量は0.08質量%以下とすることが望ましい。また、Cを含まない鋼素材でも二次再結晶は生じることから、C含有量の下限については特に設ける必要はない。したがって、Cは0質量%であってもよい。
Siは、鋼の電気抵抗を増大させ、鉄損を改善するのに有効な元素である。そのためには含有量を2.0質量%以上とすることが好ましい。一方、含有量が8.0質量%を超えると、加工性および通板性が劣化することに加え、磁束密度も低下する。そのため、Si含有量は8.0質量%以下とすることが望ましい。より好ましくは、下限が2.5質量%であって、上限が7.0質量%である。
Mnは、熱間加工性を向上させるうえで必要な元素である。そのためには含有量を0.005質量%以上とすることが好ましい。一方、含有量が1.0質量%を超えると磁束密度が劣化するため、Mn含有量は1.0質量%以下とすることが好ましい。より好ましくは、下限が0.01質量%であって、上限が0.9質量%である。
すなわち、
Ni:0.03~1.50質量%、
Sn:0.01~1.50質量%、
Sb:0.005~1.50質量%、
Cu:0.03~3.0質量%、
P:0.03~0.50質量%、
Mo:0.005~0.10質量%および
Cr:0.03~1.50質量%のうちから選ばれる1種以上
である。
なお、上記成分以外の残部はFe及び不可避的不純物である。
すなわち、前記の成分系からなる方向性電磁鋼板の鋼素材(スラブ)に、熱間圧延を施した後、必要に応じて熱延板焼鈍を行う。次いで1回または中間焼鈍をはさむ2回以上の冷間圧延を施して、最終板厚の鋼帯に仕上げる。その後、前記鋼帯に、脱炭焼鈍を施し、MgOを主成分とする焼鈍分離剤を塗布した後、コイル状に巻き取って、二次再結晶及びフォルステライト被膜の形成を目的とした仕上げ焼鈍を施す。かかる仕上げ焼鈍後の鋼帯に対し、平坦化焼鈍を施し、さらに絶縁被膜焼き付け、例えばリン酸マグネシウム系の張力被膜を形成して製品板(方向性電磁鋼板(磁区細分化工程を除く))とする。
次に、本発明における磁区細分化工程に用いる非耐熱型磁区細分化について説明する。
・エネルギービームの照射方法
本発明では、熱歪み導入のために鋼板に照射するエネルギービームとして、ガウシアン形状のビームプロファイルを持つビームを用いることで、還流磁区の総量を制御し、精度よくΔλを規定範囲内に収めることができる。特に、鋼板に入射する前に圧延方向に開口部を持つスリットを通して、一定以下のエネルギーとなるビームをカットしたビームを照射することで、顕著にΔλを規定範囲内に収めることができる。
なお、鋼板に入射する前とは、エネルギービーム光路の内、ビーム発生源から鋼板に入射する間の任意の座標である。
また、一定以下のエネルギーとなるビームをカットとは、事前に取得したビームプロファイルの最大強度に対し一定以下、例えば最大ピーク強度の40%以下、のエネルギー強度を有する領域のビームが鋼板に入射しないようにすることを意味する。カットするビームのエネルギー強度は、最大ピーク強度の50%が上限である。
エネルギービームとしては、非耐熱型磁区細分化処理に一般的に使用可能なものであれば特に限定されず、例えば、電子ビーム、レーザービーム、プラズマ炎などを使用できる。
さらに高い低鉄損・低磁歪効果を得るための手法として、ビーム経路上に円形の絞り(アパーチャ)を設置する方法が挙げられる。エネルギービーム光路の内、ビーム発生源からビーム偏向系の間にアパーチャを設置し、前記同様一定以下の強度となるビームをカットしたビームを鋼板に照射する。この様な方法で照射することで、ビーム照射方向にもビームプロファイル形状の制御が可能となり、その結果スリットに比べ鋼板に導入する歪み量をさらに低減することができる。この結果、スリットに比べ同程度のΔλについてより多くの熱歪みを導入することができ、さらに高い低鉄損効果が発現する。
本発明では、線状歪みを電子ビーム、レーザー、プラズマ炎といったエネルギービームの照射によって行う。1台以上のビーム照射装置を用いて、ビームを圧延方向に交差するように照射しながら線状歪みの導入を行う。このとき、ビームの走査方向は圧延方向から60°~120°の範囲とすることが好ましく、90°すなわち板幅方向に沿うように走査するとより好ましい。これは、板幅方向からのズレが大きくなると、鋼板に導入される歪みの量が増加し、磁歪の劣化を招くためである。なお、「線状」とは、実線、点線、破線、いずれであってもよい。
・エネルギービームの照射間隔
エネルギービームの照射間隔(隣接する熱歪み領域の間隔)は、エネルギービーム照射箇所に還流磁区が形成されることから、3mm以上10mm以下の範囲が好ましい。
・ビーム出力:30W以上10kW以下
鋼板に還流磁区を導入するには、一定以上の入熱エネルギーが必要であり、30W未満では歪み導入量が不十分であり、還流磁区が形成されない。一方、10kWを超過するような過剰な入熱を行うと、熱の拡散によって非常に広範囲に還流磁区が形成されてしまい、鉄損・騒音ともに劣化してしまう。以上より、ビームの出力としては30W以上10kW以下が好適な範囲である。より好ましくは、下限が50W程度、上限が8kW程度である。
なお、電子源として電子ビームを用いた場合、加速電圧60kV以上300kV以下、ビーム電流:0.5~40mAが好適である。
レーザー出力は、導入歪み量の観点からビーム出力より小さい方が好ましい。これは、レーザー出力を大きくすると歪みの導入量が過剰となり、渦電流損の改善以上にヒステリシス損が劣化、さらに騒音の劣化を招くためである。そのため、レーザー出力は、500W以下とするのが好ましい。一方で、レーザー出力が小さすぎると、歪みを形成するためのエネルギーが不足する。そのため、レーザー出力は、20W以上とすることが好ましい。
スポット径は、小さいほど局所的に歪みを導入することができるため好ましい。そこで本発明では、電子ビームやレーザーなどのエネルギービームのスポット径を300μm以下とすることが好ましい。280μm以下とすることがより好ましく、さらに好ましくは260μm以下である。本発明で、スポット径とは、幅30μmのスリットを用いてスリット法で取得したビームプロファイルの半値全幅を指す。
電子ビームは、気体分子によって散乱を受け、ビーム径やハロー径の増大、エネルギーの減少等が発生する。そのため、ビーム照射領域の真空度は高い方が良く、圧力にして3Pa以下とすることが好ましい。下限については特に制限を設けないが、過度に低下させると、真空ポンプなどの真空系統にかかるコストが増大する。そのため、実用上は、10-5Pa以上の圧力とすることが好ましい。
なお、レーザーは大気中で加工可能なため、この限りではない。
鋼板表面に形成される還流磁区の幅は、市販のドメインビューワー、例えばシグマハイケミカル社製MV-95を使用し、鋼板表面の磁区パターンを取得して計測を行うことができる。
ここで、本実施例においては、表1に示す成分を有し残部がFe及び不可避的不純物からなる方向性電磁鋼板素材(スラブ)を用いた。
さらに市販のマグネットビューワーを用いて、鋼板表面の磁区パターンを転写し、圧延方向を横切るように形成された還流磁区の幅を測定した。
同表より、本発明範囲であるΔλが0.010×10-6以上0.240×10-6以下であり、かつ、還流磁区幅が20μm以上240μm以下である方向性電磁鋼板では、比較例に比べ、高い低鉄損(W17/50<0.73W/kg)及び低騒音効果が得られることが分かる。また、アパーチャによってビームカットを行った実験例No.51~90のうちの発明例においては、Δλが0.010×10-6以上0.200×10-6以下であり、かつ、還流磁区幅が50μm以上240μm以下である場合に、スリットを用いた場合に比べてさらに高い低鉄損効果(W17/50<0.71W/kg)および低騒音効果を得られることが分かる。加えて、いずれの場合においても還流磁区の形成間隔が3mm以上10mm以下である場合において、より高い低鉄損性や、低騒音性を発現できることが分かる。
Claims (3)
- 圧延方向を横切る方向に線状に熱歪み領域を有し、かかる熱歪み領域内に還流磁区を備える方向性電磁鋼板であって、
前記方向性電磁鋼板を1.5T以上に励磁したときの磁束密度B―磁歪波形λ(バタフライカーブ)において、磁束密度Bが1.0~1.5Tの範囲の鋼板伸長量(Δλ)が0.010×10-6以上0.240×10-6以下であり、
かつ前記還流磁区の圧延方向長さ(還流磁区幅)が20μm以上240μm以下であることを特徴とする方向性電磁鋼板。 - 前記鋼板伸長量(Δλ)が0.010×10-6以上0.200×10-6以下であり、かつ前記還流磁区幅が50μm以上240μm以下である、請求項1に記載の方向性電磁鋼板。
- 前記還流磁区の形成間隔が3mm以上10mm以下である、請求項1または2に記載の方向性電磁鋼板。
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