Classifications

• • 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
  • H01F1/14766—Fe-Si based alloys
  • H01F1/14791—Fe-Si-Al based alloys, e.g. Sendust
• • 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
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/008—Heat treatment of ferrous alloys containing Si
• • 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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1205—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving particular fabrication steps or treatments of ingots or slabs
• • 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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties characterised by the working steps
  • C21D8/1222—Hot rolling
• • 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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties characterised by the working steps
  • C21D8/1233—Cold rolling
• • 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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties characterised by the working steps
  • C21D8/1238—Flattening; Dressing; Flexing
• • 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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties characterised by the heat treatment
  • C21D8/1272—Final recrystallisation annealing
• • 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
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • 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
  • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
• • 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
  • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
• • 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
  • 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
  • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
• • 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
  • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
  • C22C38/105—Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni
• • 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
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • 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
  • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
• • 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
  • H01F1/147—Alloys characterised by their composition
  • H01F1/14766—Fe-Si based alloys
  • H01F1/14775—Fe-Si based alloys in the form of sheets
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the present invention relates to a non-oriented electrical steel sheet, a motor core, and a motor.
• Electromagnetic steel sheets are used as materials for the cores (iron cores) of electrical equipment.
• Examples of electrical equipment include drive motors installed in automobiles, motors for various compressors such as those used in air conditioners and refrigerators, and even generators for home or industrial use. These electrical equipment require high energy efficiency, compactness, and high output. For this reason, electrical steel sheets used as the cores of electrical equipment require low iron loss and high magnetic flux density.
• Texture control is a solution, and technology has been proposed to develop a texture ( ⁇ -fiber) that has an easy magnetization axis within the steel sheet plane, is advantageous for improving magnetic properties, and can be relatively easily increased in concentration by rolling processing in hot rolling and cold rolling, which are essential processes in steel sheet manufacturing. Specifically, a texture is formed in which the ⁇ 110> direction is approximately parallel to the rolling direction (RD).
• RD rolling direction
• Patent documents 1 to 3 all disclose methods for developing the ⁇ 100 ⁇ 011> orientation, including lowering the transformation temperature and rapidly cooling after hot rolling to refine the structure.
• Patent Document 1 describes that the sheet is cooled to 250°C or less at a cooling rate of 200°C/sec or more within 3 seconds after hot rolling, that no annealing is performed between hot rolling and cold rolling, and that the cumulative reduction in cold rolling is 88% or more. This makes it possible to manufacture electrical steel sheets with grains concentrated in the ⁇ 100 ⁇ 011> orientation on the sheet surface.
• Patent Document 2 also discloses a method for producing an electrical steel sheet containing 0.6% by mass or more and 3.0% by mass or less of Al, and describes that an electrical steel sheet in which the ⁇ 100 ⁇ 011> orientation is concentrated on the steel sheet surface can be produced by a process similar to that described in Patent Document 1.
• Patent Document 3 describes that the finishing rolling temperature in hot rolling is set to the Ac3 transformation point or higher, and the steel sheet temperature is cooled to 250°C within 3 seconds after hot rolling, or that the finishing rolling temperature is set to the Ac3 transformation point -50°C or lower, and the steel sheet is cooled at a cooling rate faster than natural cooling. Furthermore, the manufacturing method described in Patent Document 3 involves performing two cold rollings with intermediate annealing in between, with no annealing between the hot rolling and the first cold rolling, and with a cumulative reduction rate of 5 to 15% in the second cold rolling. It is said that this makes it possible to manufacture an electrical steel sheet with grains accumulated in the ⁇ 100 ⁇ 011> orientation on the steel sheet surface.
• Patent documents 4 to 7 all disclose techniques for developing the ⁇ 411 ⁇ orientation, and describe optimizing the grain size in hot-rolled sheets and strengthening the ⁇ -fibers in the texture of the hot-rolled sheets.
• Patent documents 5 and 6 also state that the slab heating temperature is between 700°C and 1150°C, the start temperature of finish rolling is between 650°C and 850°C, and the end temperature of finish rolling is between 550°C and 800°C, and further that the cumulative reduction in cold rolling is 85-95%. This makes it possible to produce electrical steel sheets with ⁇ 100 ⁇ and ⁇ 411 ⁇ orientations accumulated on the steel sheet surface.
• Patent Document 7 describes that when ⁇ -fibers are developed near the surface of a hot-rolled coil steel sheet by strip casting or the like, the ⁇ h11 ⁇ 1/h12> orientation, and particularly the ⁇ 100 ⁇ 012> to ⁇ 411 ⁇ 148> orientations, are recrystallized during subsequent annealing of the hot-rolled sheet.
• the inventors have studied the above technologies and found that if one tries to improve the magnetic properties by strengthening the ⁇ 100 ⁇ 011> orientation as described in Patent Documents 1 to 3, rapid cooling immediately after hot rolling is required, which creates a problem of high manufacturing load. Furthermore, they have recognized that when a steel sheet with strengthened ⁇ 100 ⁇ 011> orientation is used as a crimped core material, the core properties expected from the material may not be obtained. After studying the cause of this, they have found that the ⁇ 100 ⁇ 011> orientation is more susceptible to changes in magnetic properties in response to stress, specifically, greater deterioration of magnetic properties (stress sensitivity) when compressive stress is applied.
• Japanese Patent Application Publication No. 2017-145462 Japanese Patent Application Publication No. 2017-193731 Japanese Patent Application Publication No. 2019-178380 Japanese Patent No. 4218077 Japanese Patent No. 5256916 Japanese Patent Application Publication No. 2011-111658 Japanese Patent Application Publication No. 2019-183185
• the present invention aims to provide a non-oriented electrical steel sheet that achieves both low iron loss and high magnetic flux density without increasing the manufacturing load and eliminating the need to reduce the sheet thickness.
• the balance has a chemical composition consisting of Fe and impurities, When the area ratio of crystal grains having ⁇ hkl ⁇ uvw> orientation (within a tolerance of 10°) to the entire field of view when the steel sheet surface is measured using a scanning electron microscope with electron backscatter diffraction (SEM-EBSD) is expressed as Ahkl-uvw, A411-011 is 15% or more, The density of precipitates is 0.0001 particles/ ⁇ m 2 to 0.3000 particles/ ⁇ m 2
• a non-oriented electrical steel sheet comprising: (2 ⁇ [Mn]+2.5 ⁇ [Ni]+[Cu])-([Si]+2 ⁇ [sol.Al]+4 ⁇ [P]) ⁇ 3.0%...(1) 10.5 ⁇ ([Si]+[Mn]) ⁇ [sol. Al] ⁇ 12.5
• a motor core comprising laminated non-oriented electrical steel sheets according to (1) above.
• a motor comprising the motor core according to
• the present invention makes it possible to provide a non-oriented electrical steel sheet, motor core, and motor that achieve both low iron loss and high magnetic flux density without increasing the manufacturing load and eliminating the need to reduce the sheet thickness.
• % which is the unit of content of each element contained in the non-oriented electrical steel sheet or steel material, means “mass %” unless otherwise specified.
• a numerical range expressed using " ⁇ ” means a range that includes the numerical values written before and after " ⁇ " as the lower and upper limits.
• the non-oriented electrical steel sheet, cold-rolled steel sheet and steel material according to this embodiment have a chemical composition in which ferrite-austenite transformation (hereinafter referred to as ⁇ - ⁇ transformation) can occur, containing C: 0.010% or less, Si: 1.50% to 4.00%, sol. Al: 0.3% to 0.7%, S: 0.010% or less, N: 0.010% or less, Ti: 0.0005% to 0.0020%, one or more elements selected from the group consisting of Mn, Ni and Cu: 2.50% to 5.00% in total, Co: 0.000% to 1.000%, Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, and P: 0.000% to 0.400%, with the balance being Fe and impurities. Furthermore, the contents of Mn, Ni, Cu, Si, sol. Al, and P satisfy the specified conditions described below. Examples of impurities include those contained in raw materials such as ores and scraps, and those contained during the manufacturing process.
• C (C: 0.010% or less) C precipitates fine carbides and inhibits grain growth, increasing iron loss and causing magnetic aging. Therefore, the lower the C content, the better. The amount of C exceeds 0.010%, and this is remarkable. Therefore, the C content is set to 0.010% or less. There is no particular lower limit for the C content, but in consideration of the cost of decarburization during refining, , and it is preferable that it is 0.0005% or more.
• Si 1.50% to 4.00% Silicon increases electrical resistance, reduces eddy current loss, reduces iron loss, increases the yield ratio, and improves punching workability into iron cores. If the Si content is less than 5.0%, these effects cannot be sufficiently obtained. Therefore, the Si content is set to 1.50% or more. On the other hand, if the Si content exceeds 4.00%, the magnetic flux density decreases and the hardness decreases. An excessive increase in Si content reduces punching workability and makes cold rolling difficult. Therefore, the Si content is set to 4.00% or less.
• Sol. Al increases the electrical resistance, reduces eddy current loss, and reduces iron loss.
• Sol. Al also contributes to improving the relative magnitude of magnetic flux density B50 with respect to saturation magnetic flux density.
• the magnetic flux density B50 is the magnetic flux density in a magnetic field of 5000 A/m.
• TiN which is a fine precipitate that inhibits the grain growth of ⁇ 411 ⁇ 110> grains due to bulging
• it is necessary to facilitate the precipitation of AlN which is relatively coarse compared to TiN. If the sol. Al content is less than 0.3%, these effects cannot be sufficiently obtained.
• Sol. Al also has the effect of promoting desulfurization during steelmaking.
• the sol. Al content is set to 0.3% or more.
• the sol. Al content exceeds 1.0%, the magnetic flux The density is decreased, and the yield ratio is decreased, which deteriorates punching workability.
• the Al content is set to 0.7% or less, and preferably, the sol. Al content is set to 0.5% to 0.6%.
• S is not an essential element and is contained, for example, as an impurity in steel. S inhibits recrystallization and grain growth during annealing by precipitating fine MnS. Therefore, the lower the S content, the lower the Such an increase in core loss and a decrease in magnetic flux density due to the inhibition of recrystallization and grain growth are remarkable when the S content exceeds 0.010%. For this reason, the S content is set to 0.010 Although there is no particular lower limit for the S content, it is preferable to set the S content to 0.0003% or more in consideration of the cost of desulfurization treatment during refining.
• N 0.010% or less
• the N content is set to 0.010% or less. is not particularly limited, but taking into consideration the cost of denitrification treatment during refining, the N content is preferably 0.001% or more.
• Ti 0.0005% to 0.0020%
• Ti is an element that is usually contained in molten steel at the steelmaking stage, and from the viewpoint of refining costs, the Ti content is set to 0.0005% or more. However, it forms a large amount of TiN, which is an indispensable precipitate, and deteriorates the magnetic properties. Therefore, the Ti content is set to 0.0020% or less, and preferably, the Ti content is set to 0.0010% to 0.0015%.
• the following condition is also satisfied as a condition under which the ⁇ - ⁇ transformation can occur: That is, when the Mn content (mass%) is [Mn], the Ni content (mass%) is [Ni], the Cu content (mass%) is [Cu], the Si content (mass%) is [Si], the sol. Al content (mass%) is [sol. Al], and the P content (mass%) is [P], the following formula (1) is satisfied in mass%.
• the upper and lower limits in formula (2) are set at 10.5 and 12.5, respectively, but outside this range, it becomes difficult to control the formation of AlN.
• formula (2) if ([Si] + [Mn]) ⁇ [sol. Al] is less than 10.5, AlN is formed in excess, which inhibits grain growth.
• ([Si] + [Mn]) ⁇ [sol. Al] exceeds 12.5, AlN is not formed sufficiently and precipitates such as TiC and MnS increase, making it impossible to reduce the number density of fine precipitates.
• Co (Co: 0.000% to 1.000%)
• Co is an effective element for inducing the ⁇ - ⁇ transformation, so it may be contained as necessary, but if it is contained in excess, the cost will increase and the magnetic flux density may decrease.
• the Co content is set to 1.000% or less.
• Sn and Sb improve the texture after cold rolling and recrystallization, and increase the magnetic flux density. Therefore, these elements may be added as necessary, but if they are included in excess, the steel may become Therefore, the Sn content and the Sb content are both set to 0.400% or less. In order to impart further effects such as magnetic properties, the Sn content is set to 0.020% to 0.400%. It is preferable that the steel contains at least one selected from the group consisting of 0.020% to 0.400% Sn and 0.020% to 0.400% Sb.
• P 0.000% to 0.400%
• P may be added to ensure the hardness of the steel sheet after recrystallization, but excessive P content leads to embrittlement of the steel. Therefore, the P content is set to 0.400% or less. Magnetic properties, etc. In order to impart the further effect of P, it is preferable to contain P in an amount of 0.020% to 0.400%.
• the area ratio of specific orientation grains is measured using OMI Analysis 7.3 (manufactured by TSL) by extracting the specific orientation of interest from the measurement area observed under the following measurement conditions using a scanning electron microscope (SEM) equipped with electron backscattering diffraction (EBSD) under the following measurement conditions (the tolerance is set to 10°, hereafter referred to as within 10°).
• SEM scanning electron microscope
• EBSD electron backscattering diffraction
• area ratio of crystal grains having a crystal orientation of ⁇ hkl ⁇ uvw> orientation (within a tolerance of 10°) relative to the measured region” and “area ratio of crystal grains having a crystal orientation of ⁇ hkl ⁇ orientation (within a tolerance of 10°) relative to the measured region” may be referred to simply as “ ⁇ hkl ⁇ uvw> ratio” and “ ⁇ hkl ⁇ ratio”, respectively.
• ⁇ hkl ⁇ uvw> ratio ⁇ hkl ⁇ ratio
• the ⁇ 411 ⁇ 011> ratio is set to 15% or more when the steel sheet surface is measured by SEM-EBSD. If the ⁇ 411 ⁇ 011> ratio is less than 15%, excellent magnetic properties cannot be obtained. Therefore, the ⁇ 411 ⁇ 011> ratio is set to 15% or more, preferably 25% or more.
• Step interval 0.3 ⁇ m (after intermediate annealing, after skin pass rolling), or 5.0 ⁇ m (after final annealing)
• Measurement object Central layer (1/2 of plate thickness) of Z surface (cut surface of steel plate cut in plate thickness direction) in the center of C direction of steel plate
• Measurement area area of 1000 ⁇ m or more in the L direction and 1000 ⁇ m or more in the C direction
• an orientation distribution function (ODF) is created under the following conditions using OMI Analysis 7.3.
• ODF orientation distribution function
• the data for the created ODF is then output, and the maximum strength is determined as the point where the ODF value is maximum within a specific orientation range (the range is specified by angles ⁇ 1 and ⁇ ).
• the area ratio of crystal grains having a specific orientation (within a tolerance of 10°) relative to the entire visual field when measured by SEM-EBSD is expressed as follows:
• the area ratio of crystal grains having a crystal orientation of ⁇ hkl ⁇ uvw> orientation (within a tolerance of 10°) relative to the entire visual field is expressed as Ahkl-uvw
• the area ratio of crystal grains having a crystal orientation of ⁇ hkl ⁇ orientation (within a tolerance of 10°) relative to the entire visual field is expressed as Ahkl, it is deemed to satisfy both of the following formulas (3) and (4).
• the magnetic properties are superior when there are many crystal grains with a ⁇ 411 ⁇ crystal orientation, but are inferior when there are many crystal grains with a ⁇ 111 ⁇ crystal orientation. Therefore, it is preferable that the ⁇ 411 ⁇ ratio exceeds the ⁇ 111 ⁇ ratio, and more preferably, the ⁇ 411 ⁇ ratio is at least twice the ⁇ 111 ⁇ ratio.
• the precipitates are mainly fine precipitates such as TiN, and also include fine precipitates such as AlN and MnS. Since the chemical composition contains Ti and Al, it is practically difficult to make the number density of these precipitates smaller than 0.0001 pieces/ ⁇ m 2. On the other hand, if the precipitates increase and the number density of the precipitates is larger than 0.3000 pieces/ ⁇ m 2 , the precipitates TiN (or AlN) become excessive and the magnetic properties deteriorate. Therefore, the number density of precipitates in the non-oriented electrical steel sheet is set to 0.0001 pieces/ ⁇ m 2 to 0.3000 pieces/ ⁇ m 2 .
• the number density of precipitates is measured, for example, by observing a sample using a transmission electron microscope (TEM) with the extraction replica method and calculating the number density. Specifically, a transmission electron microscope is used to observe the surface of the steel sheet at a depth position of 1/2 the sheet thickness t from the surface of the steel sheet with the extraction replica method, and the number of fine precipitates with a circular equivalent diameter of 20 to 500 nm in a 5 ⁇ m x 5 ⁇ m field of view in the same sample is counted. However, during observation, coarse precipitates (circular equivalent diameter of 1 ⁇ m or more) that are not included in the calculation of the number density are not included in the field of view. The number of precipitates is then counted in 10 or more fields of view in the same sample, and the average value is calculated as the number density of the precipitates. Note that image analysis software may be used when counting the number of precipitates.
• TEM transmission electron microscope
• the thickness of the non-oriented electrical steel sheet according to this embodiment There is no particular limit to the thickness of the non-oriented electrical steel sheet according to this embodiment.
• the preferred thickness of the non-oriented electrical steel sheet according to this embodiment is 0.25 to 0.50 mm. Normally, as the thickness decreases, the iron loss decreases, but the magnetic flux density decreases. In light of this, if the thickness is 0.25 mm or more, the iron loss is lower and the magnetic flux density is higher. Furthermore, if the thickness is 0.50 mm or less, low iron loss can be maintained. A more preferred lower limit for the thickness is 0.30 mm.
• the non-oriented electrical steel sheet according to this embodiment preferably has excellent magnetic properties, such as a magnetic flux density B50 in a direction at 45° to the rolling direction of 1.70 T or more, and an iron loss W10/400 in a direction at 45° to the rolling direction of 14 W/kg or less. Furthermore, in terms of strength, it is preferable that the tensile strength is 600 MPa or more.
• the tensile strength is determined by taking a JIS No. 5 test piece with the rolling direction of the non-oriented electrical steel sheet as the longitudinal direction and conducting a tensile test in accordance with JIS Z2241:2011.
• non-oriented electrical steel sheet is characterized by the non-oriented electrical steel sheet that is manufactured by performing finish annealing.
• finish annealing we will explain the characteristics of non-oriented electrical steel sheet before performing finish annealing (after performing skin pass rolling).
• the non-oriented electrical steel sheet after skin pass rolling (before finish annealing) has the following GOS (Grain Orientation Spread) value (Gs).
• GOS Gram Orientation Spread
• the GOS value is the average of the orientation differences between all measurement points (pixels) within the same grain, and the GOS value is high in crystal grains with a lot of distortion. If the GOS value Gs is small after skin pass rolling, i.e., in a low distortion state, grain growth due to bulging is likely to occur in the next process of finish annealing. Therefore, the upper limit of the GOS value Gs after skin pass rolling is set to 3.0.
• the GOS value Gs after skin pass rolling is set to 0.8 or more and 3.0 or less.
• the ⁇ -fiber has the ⁇ hkl ⁇ 011> orientation.
• the ⁇ hkl ⁇ 011> orientation is extracted (within a tolerance of 10°) using OMI Analysis 7.3. The extracted area is divided by the area of the measurement area to obtain a percentage. This percentage is the ⁇ -fiber ratio.
• the alpha fiber rate is 20% or more, and preferably 25% or more.
• the ODF strength of the ⁇ 100 ⁇ 011> orientation is set to 15 or less.
• the ⁇ 411 ⁇ 011> orientation has excellent magnetic properties and is less susceptible to stress than the ⁇ 100 ⁇ 011> orientation, so there is less magnetic deterioration in crimped cores, etc.
• the non-oriented electrical steel sheet according to this embodiment can be widely applied to applications requiring magnetic properties (high magnetic flux density and low iron loss) by forming a core, but can also be applied to applications requiring particularly high strength, such as rotors.
• the non-oriented electrical steel sheet according to this embodiment can be laminated to form a motor core, and can be widely applied to applications such as motors that have this motor core, but can also be applied to the rotor that constitutes the motor.
• hot rolling, cold rolling, intermediate annealing, a second light reduction cold rolling (hereinafter referred to as skin pass rolling), and finish annealing are performed.
• hot rolling is performed on steel material that meets the above-mentioned chemical composition to produce hot-rolled sheets.
• the hot rolling process includes a heating process and a rolling process.
• the steel material is, for example, a slab produced by normal continuous casting, and steel material of the above-mentioned composition is produced by a well-known method.
• molten steel is produced in a converter or electric furnace.
• the produced molten steel is subjected to secondary refining in a degassing facility or the like to produce molten steel having the above-mentioned chemical composition.
• the molten steel is used to cast a slab by a continuous casting method or an ingot casting method.
• the cast slab may be rolled into blooms.
• the steel material having the above-mentioned chemical composition in order to prevent Ti from going into solution and precipitating as TiN, it is preferable to heat the steel material having the above-mentioned chemical composition to 1000 to 1080°C.
• the steel material is loaded into a heating furnace or soaking furnace and heated in the furnace.
• the holding time at the above-mentioned heating temperature in the heating furnace or soaking furnace is not particularly limited, but is, for example, 30 to 200 hours.
• the heating rate from 600°C to the heating temperature is set to 0.02°C/sec or less.
• Hot rolling In the rolling process, multiple passes of rolling are performed on the steel material heated in the heating process to produce a hot-rolled plate.
• “pass” means that the steel plate passes through one rolling stand having a pair of work rolls and is reduced in pressure.
• Hot rolling may be performed, for example, by tandem rolling using a tandem rolling mill including multiple rolling stands arranged in a row (each rolling stand having a pair of work rolls) to perform multiple passes of rolling, or by reverse rolling using a pair of work rolls to perform multiple passes of rolling. From the viewpoint of productivity, it is preferable to perform multiple rolling passes using a tandem rolling mill.
• the rolling process (rough rolling and finish rolling) is carried out at a temperature in the gamma region or gamma-alpha mixed region (above Ar1 point).
• hot rolling is carried out so that the temperature when passing through the final pass of finish rolling (finish rolling temperature FT (°C)) is above Ar1 point.
• the finishing rolling temperature FT means the surface temperature (°C) of the steel plate at the exit of the rolling stand where the final pass is performed in the rolling process in the hot rolling process.
• the finishing rolling temperature FT can be measured, for example, by a thermometer installed at the exit of the rolling stand where the final pass is performed.
• the finishing rolling temperature FT means, for example, the average value of the temperature measurements of the parts excluding the leading end section and the trailing end section when the entire length of the steel plate is divided into 10 equal sections in the rolling direction.
• cooling after the rolling process transforms the austenite into ferrite, resulting in high strain and moderately fine crystal grains.
• the cooling conditions are such that cooling begins 0.1 seconds after the final pass of finish rolling, and the surface temperature of the hot-rolled sheet is 300°C or higher and Ar1 point or lower after 3 seconds, without immediate quenching.
• immediate quenching in this way, special quenching equipment is not required, which also has manufacturing (cost) advantages.
• cold rolling is then performed with a suitable crystal grain size that is not overly refined, ⁇ -fiber develops after intermediate annealing, and the ⁇ 411 ⁇ 011> orientation, which is usually difficult to develop, can develop after the subsequent skin pass and finish annealing.
• the texture of a hot-rolled sheet is one in which unrecrystallized austenite is transformed if the sheet is quenched immediately after rolling, and one in which partially recrystallized austenite is transformed if quenching is omitted. If quenching is performed immediately after finish rolling, austenite accumulates in the ⁇ 100 ⁇ 011> orientation in the texture after the subsequent finish annealing, and if quenching is omitted after finish rolling, austenite accumulates in the ⁇ 411 ⁇ 011> orientation in the texture after the subsequent finish annealing. Therefore, it is thought that it is important to transform the partially recrystallized austenite in order to strengthen the ⁇ 411 ⁇ 011> orientation.
• the cooling conditions are preferably such that the average crystal grain size in the hot-rolled sheet before cold rolling is 3 to 10 ⁇ m. If the crystal grains become too coarse, it becomes difficult for ⁇ -fiber to develop after cold rolling and intermediate annealing, and the desired ⁇ 411 ⁇ 011> ratio may not be obtained. Moreover, if the grains are made too fine, the desired ⁇ 411 ⁇ 011> ratio cannot be obtained. Therefore, in order to make the average crystal grain size in the hot-rolled sheet before cold rolling 3 to 10 ⁇ m, the temperature is set to Ar1 point or lower within 3 seconds after passing the final pass of finish rolling. The grain size can be measured, for example, by the intercept method.
• the surface temperature of the hot rolled sheet 3 seconds after passing the final pass of the finish rolling is measured by the following method.
• a cooling device and a conveying line are arranged downstream of the hot rolling mill.
• a thermometer for measuring the surface temperature of the hot rolled sheet is arranged at the exit side of the rolling stand that performs the final pass of the hot rolling mill.
• multiple thermometers are arranged along the conveying line on the conveying rollers arranged downstream of the rolling stand.
• the cooling device is arranged downstream of the rolling stand that performs the final pass.
• a thermometer is arranged at the entrance side of the water cooling device.
• the cooling device may be, for example, a well-known water cooling device or a well-known forced air cooling device.
• the cooling device is a water cooling device.
• the cooling liquid of the water cooling device may be water or a mixed fluid of water and air.
• the hot-rolled sheet temperature is measured using a thermometer installed on the hot-rolling equipment line. The temperature is then measured three seconds after the final pass of the finishing rolling.
• hot-rolled sheet annealing means, for example, heat treatment in which the temperature rise is below the Ac1 point and is 300°C or higher.
• the hot rolled sheet is subjected to cold rolling without being annealed.
• Cold rolling may be performed, for example, by using a tandem rolling mill including multiple rolling stands (each having a pair of work rolls) arranged in a row to perform multiple passes of rolling.
• reverse rolling may be performed using a Sendzimir rolling mill or the like having a pair of work rolls to perform single pass or multiple passes of rolling. From the viewpoint of productivity, it is preferable to perform multiple passes of rolling using a tandem rolling mill.
• cold rolling is performed without annealing treatment during the cold rolling.
• cold rolling is performed in multiple passes without annealing treatment between the cold rolling passes.
• Cold rolling may be performed in only one pass using a reverse rolling mill.
• cold rolling is performed continuously in multiple passes (passes at each rolling stand).
• the reduction rate RR1 (%) in the cold rolling is set to 75 to 95%.
• intermediate annealing is performed.
• the intermediate annealing temperature T1 (°C) is the sheet temperature (temperature of the steel sheet surface) near the exit port of the annealing furnace.
• the sheet temperature in the annealing furnace can be measured by a thermometer placed at the exit port of the annealing furnace.
• the holding time at the intermediate annealing temperature T1 in the intermediate annealing process may be a time known to those skilled in the art.
• the holding time at the intermediate annealing temperature T1 is, for example, 5 to 60 seconds, but the holding time at the intermediate annealing temperature T1 is not limited to this.
• the heating rate up to the intermediate annealing temperature T1 may also be a known condition.
• the heating rate up to the intermediate annealing temperature T1 is, for example, 10.0 to 20.0°C/second, but the heating rate up to the intermediate annealing temperature T1 is not limited to this.
• the atmosphere during intermediate annealing is not particularly limited, but for example, an atmospheric gas (dry) containing 20% H2 and the balance N2 is used as the atmosphere during intermediate annealing.
• the cooling rate of the steel sheet after intermediate annealing is not particularly limited, and the cooling rate is, for example, 5.0 to 60.0 ° C. / sec.
• the resulting cold-rolled steel sheet has an ⁇ -fiber ratio (within a 10° tolerance) of 15% or more as measured by SEM-EBSD.
• ⁇ -fiber ratio within a 10° tolerance
• ⁇ -fiber which is likely to produce ⁇ 411 ⁇ 011> orientation, is developed by transforming partially recrystallized austenite into ferrite, cold rolling the hot-rolled sheet with an average grain size of 3 to 10 ⁇ m after hot rolling, and then intermediate annealing.
• the cold-rolled steel sheet produced in this manner is then subjected to skin-pass rolling under the conditions described below, followed by finish annealing, to produce the non-oriented electrical steel sheet of the present invention.
• the cold rolled steel sheet after the intermediate annealing process is rolled (cold rolling) at room temperature in the atmosphere.
• a reverse rolling mill such as the Sendzimir rolling mill mentioned above, or a tandem rolling mill is used.
• skin pass rolling rolling is performed without annealing treatment in between.
• multiple passes are rolled without annealing treatment between passes.
• Skin pass rolling may be performed in only one pass using a reverse rolling mill.
• rolling is performed continuously in multiple passes (passes at each rolling stand).
• the strain introduced into the steel sheet is first reduced by intermediate annealing. Then, skin pass rolling is performed. In this way, the excessive strain introduced by cold rolling is reduced in intermediate annealing, and by performing intermediate annealing, the preferential recrystallization of ⁇ 111 ⁇ grains in the steel sheet surface is suppressed, and ⁇ 411 ⁇ 011> crystal orientation grains are retained. Then, an appropriate amount of strain is introduced into each crystal grain in the steel sheet in skin pass rolling, making it easier for grain growth due to bulging to occur in the next process of finish annealing.
• the reduction ratio RR2 in the skin pass rolling is set to 5 to 20%.
• the reduction rate RR2 is set to 5-20%.
• the number of passes in skin pass rolling may be only one pass (i.e., only one rolling), or it may be multiple passes.
• finish annealing is performed at 750°C or higher and Ac1 point or lower for 2 hours or more. If the finish annealing temperature T2 (°C) is less than 750°C, grain growth due to bulging does not occur sufficiently. In this case, the concentration of the ⁇ 411 ⁇ 011> orientation decreases. If the finish annealing temperature T2 exceeds Ac1 point, part of the steel plate structure is transformed into austenite, grain growth due to bulging does not occur, and the desired ⁇ 411 ⁇ 011> ratio cannot be obtained.
• the annealing time is less than 2 hours, even if the finish annealing temperature T2 is 750°C or higher and Ac1 point or lower, grain growth due to bulging does not occur sufficiently, and the concentration of the ⁇ 411 ⁇ 011> orientation decreases.
• the upper limit of the annealing time for finish annealing is not particularly limited, but the effect is saturated even if the annealing time exceeds 10 hours, so the preferred upper limit is 10 hours.
• the finish annealing temperature T2 is the sheet temperature (the temperature of the steel sheet surface) near the exit port of the annealing furnace.
• the furnace temperature of the annealing furnace can be measured by a thermometer placed at the exit port of the annealing furnace.
• the heating rate TR2 up to the final annealing temperature T2 in the final annealing process may be any heating rate known to those skilled in the art, and the holding time ⁇ t2 (seconds) at the final annealing temperature T2 may also be any time known to those skilled in the art.
• the holding time ⁇ t2 refers to the holding time after the surface temperature of the steel sheet reaches the final annealing temperature T2.
• the preferred heating rate TR2 to the finishing annealing temperature T2 in the finishing annealing process is 0.1°C/sec or more and less than 10.0°C/sec. If the heating rate TR2 is 0.1°C/sec or more and less than 10.0°C/sec, grain growth due to bulging occurs sufficiently. In this case, the concentration of the ⁇ 411 ⁇ 011> crystal orientation increases, and the crystal grains on the ND surface at the center of the plate thickness become even less likely to vary.
• the heating rate TR2 is determined by the following method.
• a thermocouple is attached to a steel sheet having the above chemical composition and obtained by carrying out the above steps from hot rolling to skin pass to prepare a sample steel sheet.
• the sample steel sheet to which the thermocouple is attached is heated, and the time from the start of heating to the time it reaches the finish annealing temperature T2 is measured.
• the heating rate TR2 is determined based on the measured time.
• the holding time ⁇ t2 at the finishing annealing temperature T2 in the finishing annealing process is 2 hours or more. If the holding time ⁇ t2 is 2 hours or more, grain growth of the ⁇ 411 ⁇ 110> grains occurs due to bulging, and the strength is increased by fine grain strengthening. In this case, the concentration of the ⁇ 411 ⁇ 011> crystal orientation is further increased, and the crystal grains on the ND surface at the center position of the plate thickness are further prevented from varying.
• the lower limit of the holding time ⁇ t2 is 2 hours, and preferably 3 hours. As mentioned above, the preferred upper limit of the holding time ⁇ t2 is 10 hours, and more preferably 5 hours.
• the atmosphere during the final annealing process is not particularly limited.
• an atmospheric gas (dry) containing 20% H2 and the balance N2 is used as the atmosphere during the final annealing process.
• the cooling rate of the steel sheet after the final annealing is not particularly limited. The cooling rate is, for example, 5 to 20 ° C / sec.
• the process up to skin pass rolling can be carried out by a steel sheet manufacturing company, and the non-oriented electrical steel sheet can be punched or laminated at the core manufacturing company to which it is shipped, after which stress relief annealing can be carried out as an alternative to finish annealing, at an annealing temperature of 750°C or higher and Ac1 point or lower for an annealing time of 2 hours or longer.
• the non-oriented electrical steel sheet according to this embodiment can be manufactured.
• the manufacturing method of the non-oriented electrical steel sheet according to this embodiment is not limited to the above manufacturing process.
• shot blasting and/or pickling may be performed after hot rolling and before cold rolling.
• shot blasting shot blasting is performed on the steel sheet after hot rolling to destroy and remove scale formed on the surface of the steel sheet after hot rolling.
• pickling pickling treatment is performed on the steel sheet after hot rolling.
• hydrochloric acid aqueous solution is used as the pickling bath for the pickling treatment. Scale formed on the surface of the steel sheet is removed by pickling.
• Shot blasting may be performed after hot rolling and before cold rolling, and then pickling may be performed.
• pickling may be performed after hot rolling and before cold rolling, and shot blasting may not be performed. Shot blasting may be performed after hot rolling and before cold rolling, and pickling treatment may not be performed.
• shot blasting and pickling are optional processes. Therefore, it is not necessary to perform both the shot blasting process and the pickling process after hot rolling and before cold rolling.
• the method for manufacturing an electrical steel sheet according to this embodiment may further include coating after the final annealing.
• an insulating film is formed on the surface of the steel sheet after the final annealing.
• the type of insulating film is not particularly limited.
• the insulating film may be made of organic or inorganic components, and the insulating coating may contain both organic and inorganic components.
• inorganic components include dichromate-boric acid, phosphoric acid, and silica.
• organic components include general acrylic, acrylic styrene, acrylic silicone, silicone, polyester, epoxy, and fluorine-based resins. When paintability is taken into consideration, emulsion-type resins are preferred.
• An insulating coating that exhibits adhesive properties when heated and/or pressurized may be applied. Examples of insulating coatings with adhesive properties include acrylic, phenolic, epoxy, and melamine resins.
• coating is an optional process. Therefore, coating does not have to be performed after final annealing.
• the non-oriented electrical steel sheet according to the present embodiment is not limited to the above-mentioned manufacturing method, as long as the composition is within the above-mentioned range, and further the area ratio of crystal grains having ⁇ 411 ⁇ 011> orientation (within a tolerance of 10°) relative to the entire field of view when the steel sheet surface is measured by electron backscatter diffraction (EBSD) is 15% or more, and the number density of precipitates is 0.0001 particles/ ⁇ m 2 to 0.3000 particles/ ⁇ m 2 .
• EBSD electron backscatter diffraction
• non-oriented electrical steel sheet according to an embodiment of the present invention will be specifically described with reference to examples.
• the examples shown below are merely examples of the non-oriented electrical steel sheet according to an embodiment of the present invention, and the non-oriented electrical steel sheet according to the present invention is not limited to the examples below.
• the hot-rolled steel sheet was not annealed, but scale was removed by pickling, and cold rolling was performed at the reduction ratio RR1 shown in Table 2. Then, intermediate annealing was performed in an atmosphere of 20% hydrogen and 80% nitrogen, and intermediate annealing temperature T1 was controlled to the temperature shown in Table 2 for 30 seconds.
• the magnetic flux density B50 and the iron loss W10/400 were measured, and the iron loss deterioration rate of the iron loss W10/50 under compressive stress was obtained as an index of stress sensitivity.
• the magnetic flux density B50 55 mm square samples were taken in two directions, 0° and 45°, in the rolling direction as measurement samples. Then, these two types of samples were measured, and the value in the 45° direction with respect to the rolling direction was taken as the magnetic flux density B50 in the 45° direction, and the average value of 0°, 45°, 90°, and 135° with respect to the rolling direction was taken as the magnetic flux density B50 all around average.
• Comparative example No. 5 exceeded the upper limit of formula (2), so there was a shortage of AlN generation, and finer TiN was precipitated in large amounts. As a result, the number density of precipitates was high, and the iron loss W10/400 and iron loss deterioration rate were poor. In the comparative example, No. 6, which was below the lower limit of formula (2), the number density of precipitates was high due to the excessive formation of AlN. As a result, the iron loss W10/400 and iron loss deterioration rate were poor.
• Comparative Example No. 8 exceeded the upper limit of formula (2) and contained excessive Ti. Furthermore, the heating rate during slab heating was high, which resulted in the formation of a large amount of TiN, resulting in a high number density, and a shortage of Si, resulting in poor iron loss W10/400. Comparative Example No. 9 contained an excessive total amount of one or more elements selected from the group consisting of Mn, Ni, and Cu, which led to segregation and two-piece splitting during cold rolling, after which production was discontinued. Comparative Example No. 10 did not undergo skin pass rolling, resulting in a small ⁇ 411 ⁇ 011> ratio, and poor magnetic flux density B50 (45° direction), iron loss W10/400, and iron loss deterioration rate. Comparative Example No. In No.
• the reduction rate RR2 in the skin pass rolling was too large, resulting in a small ⁇ 411 ⁇ 011> ratio, and the magnetic flux density B50 (45° direction) and iron loss W10/400 were poor.
• the slab heating temperature ST was too high, resulting in a large amount of fine TiN precipitation and a high number density. As a result, the iron loss W10/400 was poor.
• the present invention can provide a non-oriented electrical steel sheet, motor core, and motor that achieve both low iron loss and high magnetic flux density without increasing the manufacturing load and eliminating the need to reduce the sheet thickness, and is of great industrial value.

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