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
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  • 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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/26—Methods of annealing
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  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/008—Heat treatment of ferrous alloys containing Si
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  • 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
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  • 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
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  • 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
  • C21D8/1261—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 following 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
  • C21D8/1244—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
  • C21D8/1266—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 between cold rolling steps
• • 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
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  • 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%
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  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
• • C—CHEMISTRY; METALLURGY
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  • 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
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  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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  • 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
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  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
• • C—CHEMISTRY; METALLURGY
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  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
• • C—CHEMISTRY; METALLURGY
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  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • C—CHEMISTRY; METALLURGY
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  • 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
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
• • C—CHEMISTRY; METALLURGY
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  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
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  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
• • C—CHEMISTRY; METALLURGY
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  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
• • C—CHEMISTRY; METALLURGY
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  • 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

• This disclosure relates to non-oriented electrical steel sheets.
• Non-oriented electrical steel sheets are used, for example, in the iron cores of motors, and are required to have excellent magnetic properties, such as low iron loss and high magnetic flux density, in the average of all directions parallel to the sheet surface (hereinafter sometimes referred to as the "all-around average (all-directional average) within the sheet surface").
• all-around average all-directional average
• various technologies have been proposed so far, it is difficult to obtain sufficient magnetic properties in all directions within the sheet surface. For example, even if sufficient magnetic properties can be obtained only in a specific direction within the sheet surface, sufficient magnetic properties may not be obtained in other directions.
• ⁇ stabilizing elements such as Mn, Cu, and Ni is utilized from the viewpoint of lowering the transformation temperature and retarding recovery recrystallization to promote the accumulation of strain.
• Mn is known as a segregation element, and if the content increases, it segregates in the center of the thickness of the hot-rolled sheet, causing cracks when the hot-rolled sheet is cold-rolled.
• ⁇ 100 ⁇ 011> orientation developed through technology utilizing the ⁇ phase transformation is predominant, there is significant in-plane anisotropy, and a new type of crystal orientation control is required.
• the present disclosure aims to provide a non-oriented electrical steel sheet that has a chemical composition in which Mn is suppressed so that rollability is not an issue, and the contents of elements such as Mn, Cu, and Ni are optimized, and that has small in-plane anisotropy and excellent magnetic properties can be obtained in the direction at 45° from the rolling direction.
• a non-oriented electrical steel sheet In mass percent, C: 0.0100% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.0%, S: 0.0100% or less, N: 0.0100% or less, Mn: 0.10% or more, One or more selected from Mn, Ni, and Cu: less than 2.50% in total; Mo: 0.00% to less than 2.50% Cr: 0.00% to less than 2.50%; Ti: 0.000% to 0.005%, Nb: 0.000% to 0.005%, Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0.0100% in total;
• the alloy has a chemical composition in which the transformation temperature Ar 3 (°C) defined by the following formula (1) is 750 to 1050°C, with the balance
• Al content is [sol. Al], and the P content is [P], in mass %, And the plate thickness is 0.50 mm or less,
• the area ratio of ⁇ 411 ⁇ crystal grains is Sac
• the area ratio of ⁇ 110 ⁇ crystal grains is Sag
• the area ratio occupied by ⁇ 411 ⁇ crystal grains in a region up to 20% from the high KAM (Kernel Average Misorientation) value is Sbc. Sac > 0.120, Sac > Sbc > Sag, and 0.050 > Sag are satisfied.
• Ar 3 (°C) 1020-325 ⁇ [C]+33 ⁇ [Si]+287 ⁇ [P]+80 ⁇ [sol.
• a non-oriented electrical steel sheet In mass percent, C: 0.0100% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.0%, S: 0.0100% or less, N: 0.0100% or less, Mn: 0.10% or more, One or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu: less than 2.50% in total; Mo: 0.00% to less than 2.50% Cr: 0.00% to less than 2.50%; Ti: 0.000% to 0.005%, Nb: 0.000% to 0.005%, Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0.0100% in total;
• the alloy has a chemical composition in which the transformation temperature Ar 3 (°C) defined by the following formula (1) is
• Al content is [sol. Al], and the P content is [P], in mass %, And the plate thickness is 0.50 mm or less,
• the area ratio of ⁇ 411 ⁇ crystal grains is Sac
• the area ratio of ⁇ 110 ⁇ crystal grains is Sag
• the area ratio occupied by ⁇ 411 ⁇ crystal grains in a region up to 20% from the high KAM (Kernel Average Misorientation) value is Sbc. Sac > 0.120, Sac > Sbc > Sag, and 0.050 > Sag are satisfied.
• Ar 3 (°C) 1020-325 ⁇ [C]+33 ⁇ [Si]+287 ⁇ [P]+80 ⁇ [sol.
• the magnetic flux density B50 in the rolling direction may be 1.58 T or more, and the magnetic flux density B50 in a direction at 45° to the rolling direction may be 1.70 T or more.
• non-oriented electrical steel sheet that has a chemical composition in which Mn is suppressed so that rollability is not an issue, and the contents of elements such as Mn, Cu, and Ni are optimized, and that can obtain excellent magnetic properties in the direction at 45° from the rolling direction.
• the inventors conducted extensive research to solve the above problems. As a result, they discovered that by limiting the amount of Mn added to ensure rollability, adjusting the composition, and then optimizing the hot rolling conditions to form an appropriate ⁇ -processed grain structure at the hot-rolled sheet stage, the ⁇ 411 ⁇ crystal orientation is developed in the subsequent cold rolling and intermediate annealing. This ⁇ 411 ⁇ crystal orientation is further enriched by strain-induced grain boundary migration (SIBM) caused by final annealing when the intermediate annealed sheet is subjected to skin-pass rolling and then final annealing. It was also discovered that enriching the ⁇ 411 ⁇ crystal orientation is effective in reducing the in-plane anisotropy of the magnetic properties and improving the 45° direction from the rolling direction.
• SIBM strain-induced grain boundary migration
• the inventors conducted further intensive research based on these findings and came up with the present disclosure.
• non-oriented electrical steel sheet includes not only coil-shaped or cut-plate steel sheet, but also steel sheet processed into a specific shape as a material for products (components) such as motor cores, and further steel sheet laminated after processing to form motor cores.
• the chemical composition of the non-oriented electrical steel sheet according to the embodiment of the present disclosure and the steel material used in the manufacturing method thereof will be described.
• the chemical composition of the non-oriented electrical steel sheet indicates the content when the base material excluding the coating, etc. is taken as 100%.
• the upper limit value of a certain numerical range may be replaced by the upper limit value of another numerical range described in stages, or may be replaced by a value shown in the examples.
• the lower limit value of a certain numerical range may be replaced by the lower limit value of another numerical range described in stages, or may be replaced by a value shown in the examples.
• the non-oriented electrical steel sheet according to this embodiment has a chemical composition in which ferrite-austenite transformation (hereinafter, ⁇ - ⁇ transformation) can occur, In mass percent, C: 0.0100% or less, Si: 1.50% to 4.00%, sol.
• ⁇ - ⁇ transformation ferrite-austenite transformation
• Al 0.0001% to 1.0%, S: 0.0100% or less, N: 0.0100% or less, Mn: 0.10% or more, One or more selected from Mn, Ni, and Cu: less than 2.50% in total; Mo: 0.0% to less than 2.5% Cr: 0.0% to less than 2.5% Ti: 0.000% to 0.005% Nb: 0.000% to 0.005% Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%, and one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0.0000% to 0.0100% in total, and further, the contents of C, Si, P, sol. Al, Mn, Mo, Cu, Cr, and Ni satisfy the specified conditions described later, with the balance being Fe and impurities.
• one or more elements selected from Mn, Ni, Co, Pt, Pb, Au, and Cu are contained in a total amount of less than 2.50%.
• impurities examples include those contained in raw materials such as ores and scraps, and those contained during the manufacturing process.
• C 0.0100% or less
• the C content is set to 0.0100% or less.
• the reduction in the C content contributes to the uniform improvement of the magnetic properties in all directions in the sheet surface.
• the content is preferably 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 1.50%, these effects cannot be sufficiently obtained. Therefore, the Si content is set to 1.50% or more.
• the Si content is preferably more than 1.80%, and more preferably 2.00 or more.
• the Si content exceeds 4.00%, the magnetic flux density decreases, the punching workability decreases due to an excessive increase in hardness, and cold rolling becomes difficult. Not more than 4.00%.
• sol.Al 0.0001% to 1.0%
• Sol. Al increases 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. If the sol. Al content is less than 0.0001%, these functions and effects cannot be fully obtained. Furthermore, Al also has the effect of promoting desulfurization in steelmaking. Therefore, the sol. Al content is set to 0.0001% or less. On the other hand, if the sol. Al content exceeds 1.0%, the magnetic flux density decreases, the yield ratio decreases, and punching workability decreases. shall be 1.0% or less.
• the total content of Si and sol.Al is preferably more than 1.80, and more preferably 2.00 or more.
• sol. Al means acid-soluble Al that is not in the form of an oxide such as Al 2 O 3 and is soluble in acid.
• the magnetic flux density B50 is the magnetic flux density in a magnetic field of 5000 A/m.
• 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 0.0100%. For this reason, the S content is set to 0.0100 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 0.0100% or less
• the Nitrogen content be 0.0010% or more.
• the lower limit of the total content of Mn, Ni, and Cu is not particularly limited, but may be, for example, 0.10% or more, 0.50% or more, 1.00% or more, or even 2.00% or more.
• Mn, Ni, Co, Pt, Pb, Au, and Cu are selected from Mn, Ni, Co, Pt, Pb, Au, and Cu: less than 2.50% in total.
• Mn, Ni, and Cu, Co, Pt, Pb, and Au also increase the anisotropy of the magnetic properties, so in this embodiment, it is preferable to keep the total content of these elements below 2.50%. Furthermore, since these elements reduce the magnetic flux density, it is preferable to keep the total content below 2.00%.
• the lower limit of the total of Mn, Ni, Co, Pt, Pb, Au, and Cu is not particularly limited, but may be, for example, 0.10% or more, 0.50% or more, 1.00% or more, or even 2.00% or more.
• the alloy cost of Co, Pt, Pb, and Au is high, active addition should be avoided. Furthermore, even considering the control of the Ar3 transformation point, which is one of the features of this embodiment, it is preferable to control the Ar3 transformation point by containing Mn, Ni, and Cu. For this reason, the total amount of Co, Pt, Pb, and Au should be less than 0.5%, more preferably 0.1% or less, and should be kept within the range of unavoidable elements, and there is no need to actively add them (it may be 0%).
• the non-oriented electrical steel sheet and steel material according to this embodiment further satisfy the following condition as a condition under which ⁇ - ⁇ transformation can occur:
• the C content is [C]
• the Mo content is [Mo]
• the Cr content is [Cr]
• the Mn content is [Mn]
• the Ni content is [Ni]
• the Cu content is [Cu]
• the Si content is [Si]
• the sol. Al content is [sol. Al]
• the P content is [P] in mass%
• the transformation temperature Ar 3 (°C) defined by the following formula (1) is 750 to 1050°C.
• Ar 3 (°C) 1020-325 ⁇ [C]+33 ⁇ [Si]+287 ⁇ [P]+80 ⁇ [sol.
• the transformation point is not in an appropriate temperature range, so sufficient magnetic flux density cannot be obtained even if the manufacturing method described below is applied. If the Ar3 transformation point is less than 750 ° C, the hot rolling temperature is lowered, so the deformation resistance increases and the load on the rolling mill becomes too large, and the amount of added elements increases, which leads to a decrease in toughness of the hot-rolled sheet and the cold-rolled sheet, so this value is set as the lower limit.
• Mn 0.10% or more, the total of one or more selected from Mn, Ni, and Cu, or the total of one or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu is less than 2.5%)
• Mn lowers the Ar3 transformation point, and in the component system of the non-oriented electrical steel sheet according to this embodiment, it is possible to refine the crystal grains of the hot-rolled sheet by phase transformation.
• Mn is an element that increases the electrical resistance of steel and reduces iron loss. Therefore, Mn is contained at 0.10% or more. From this viewpoint, Mn is preferably contained at 0.50% or more. More preferably, it is 1.00% or more.
• Mn is an element that is prone to segregation, and if the content increases, not only does it cause cold work cracks due to segregation, but it also reduces the saturation magnetic flux density and prevents the increase in the magnetic flux density of the steel sheet.
• MnS is generated excessively, and the cold workability is reduced. Therefore, the Mn content is limited within the above range. Specifically, the upper limit of the Mn content is less than 2.5%, preferably 2.3 mass% or less, and more preferably 2.0 mass%.
• Cu the total content of one or more selected from Mn, Ni, and Cu, or the total content of one or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu is less than 2.5%)
• Cu is an element that increases the electrical resistance of the steel sheet and reduces iron loss, similar to Mn, and reduces the Ar3 transformation point, enabling the fine grain size of the hot-rolled sheet to be refined by phase transformation in the chemical composition of the non-oriented electrical steel sheet according to this embodiment.
• the Cu content is limited to less than 2.5%.
• the upper limit of the Cu content is not limited, but may be 1.6 mass% or less, preferably 1.2 mass% or less, and more preferably 1.0 mass% or less.
• the lower limit of the Cu content is not particularly limited, but may be, for example, 0.01% or more.
• Ni the total content of one or more selected from Mn, Ni, and Cu, or the total content of one or more selected from Mn, Ni, Co, Pt, Pb, Au, and Cu is less than 2.5%)
• Ni increases the electrical resistance of the steel sheet and reduces iron loss.
• Ni further lowers the A3 transformation point, enabling the crystal grains to be refined by phase transformation in the chemical composition of the non-oriented electrical steel sheet according to this embodiment.
• the Ni content is limited to less than 2.5%.
• the upper limit of the Ni content is preferably 1.0 mass% or less, and more preferably 0.7 mass% or less.
• the lower limit of the Ni content is not particularly limited and may be 0%, but may be, for example, 0.01% or more.
• Mo 0.0% to less than 2.58%
• Mo is an element that lowers the Ar3 transformation point and enables the grain size of the hot-rolled sheet to be refined by phase transformation in the chemical composition of the non-oriented electrical steel sheet according to this embodiment. Therefore, Mo may be contained as necessary, and it is preferable to contain 0.1% or more.
• Mo is 2.5% Since a Mo content of more than this amount significantly deteriorates cold workability, the Mo content is set to less than 2.5%.
• Cr 0.0% to less than 2.5%)
• Cr is an element that lowers the Ar3 transformation point and enables the refinement of the grain size of the hot-rolled sheet by phase transformation in the chemical composition of the non-oriented electrical steel sheet according to this embodiment, and has the effect of improving not only strength adjustment and corrosion resistance, but also high-frequency characteristics in particular. Therefore, Cr may be contained as necessary, and it is preferable to contain 0.1% or more.
• excessive Cr content not only saturates the effect and increases the raw material cost, but also reduces the saturation magnetic flux density and prevents the magnetic flux density of the steel sheet from increasing. For this reason, the Cr content is set to less than 2.5%.
• Ti when present in the form of a solid solution or TiN, suppresses recrystallization and contributes to refinement of the austenite grain size. Therefore, Ti may be added as necessary, and it is recommended that Ti content be 0.001% or more. On the other hand, if the Ti content exceeds 0.005%, various precipitates such as TiN, TiS, and TiC are formed, which deteriorates the core loss characteristics, so the Ti content is set to 0.005% or less.
• Nb when present in the form of a solid solution or NbN, suppresses recrystallization and contributes to refinement of the austenite grain size. Therefore, Nb may be added as necessary, and it is recommended that Nb be added in an amount of 0.001% or more. On the other hand, if the Nb content exceeds 0.005%, various precipitates such as NbN and NbC are generated and the core loss characteristics are deteriorated, so the Nb content is set to 0.005% 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. P may be added to ensure the hardness of the steel sheet after recrystallization, but excessive P should not be added. Therefore, the P content is set to 0.400% or less.
• Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd react with S in the molten steel during casting of the molten steel to form precipitates of sulfides or oxysulfides, or both.
• Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd may be collectively referred to as "coarse precipitate forming elements”.
• the particle size of the precipitates of the coarse precipitate forming elements is about 1 ⁇ m to 2 ⁇ m, which is much larger than the particle size (about 100 nm) of fine precipitates such as MnS, TiN, AlN, TiC, and NbC. For this reason, these fine precipitates adhere to the precipitates of the coarse precipitate forming elements, and are less likely to inhibit recrystallization and grain growth during annealing such as intermediate annealing. In order to fully obtain these effects, it is preferable that the total amount of the coarse precipitate forming elements is 0.0005% or more.
• the total content of the coarse precipitate forming elements is set to 0.0100% or less.
• the upper limit of the total content of the coarse precipitate forming elements may be set to 0.0080% or less, or further to 0.0050% or less.
• the remainder of the chemical composition other than those described above may be Fe and impurities.
• Impurities refer to elements that are mixed in the steel raw materials and/or the steelmaking process.
• other elements may be contained in place of a portion of Fe to the extent that the effect of the present invention is not lost.
• B, O, V, Bi, W, and Y may each be contained in an amount of 0.10% or less.
• the total amount of impurities is preferably 5.00% or less, and more preferably 1.00% or less.
• the chemical composition is determined by the following method.
• the chemical composition may be measured by a general analysis method for steel.
• the chemical composition may be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry).
• the chemical composition is specified by measuring a test piece taken from the steel plate with a predetermined measuring device under conditions based on a calibration curve created in advance.
• C and S may be measured using a combustion-infrared absorption method
• N may be measured using an inert gas fusion-thermal conductivity method.
• O may be measured using an inert gas fusion-non-dispersive infrared absorption method. If the surface has an insulating coating, it may be mechanically removed using a minitor or the like before being subjected to analysis.
• the metal structure of the non-oriented electrical steel sheet according to this embodiment will be described.
• the manufacturing method will be described in detail later, but the non-oriented electrical steel sheet according to this embodiment has a chemical composition in which ⁇ - ⁇ transformation can occur.
• the thickness of the non-oriented electrical steel sheet according to this embodiment is 0.50 mm or less.
• the preferred thickness of the non-oriented electrical steel sheet according to this embodiment is 0.10 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 0.10 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 0.20 mm, and an even more preferred lower limit is 0.30 mm.
• the non-oriented electrical steel sheet according to this embodiment has a strain distribution that allows a high magnetic flux density to be obtained in the direction 45° from the rolling direction. Specifically, the non-oriented electrical steel sheet according to this embodiment satisfies Sac>0.120, Sac>Sbc>Sag, and 0.050>Sag.
• Sac is the area ratio of ⁇ 411 ⁇ crystal grains in an arbitrary cross section of the steel sheet after skin-pass rolling
• Sag is the area ratio of ⁇ 110 ⁇ crystal grains in an arbitrary cross section of the steel sheet after skin-pass rolling.
• Sag Sallg/Sall.
• a ⁇ 411 ⁇ grain (or a ⁇ 110 ⁇ grain) is a grain defined within a tolerance of 10° from a target crystal orientation. In other words, the crystal orientation has a tolerance of ⁇ 10° from the target crystal orientation.
• Sbc is the area ratio of ⁇ 411 ⁇ crystal grains in a region that exhibits a given KAM value.
• the KAM value indicates the difference in orientation between a measurement point and an adjacent measurement point within the same grain (however, if the adjacent measurement points are different crystal grains, they are excluded from the KAM calculation).
• the KAM value is high in areas with a lot of distortion. By extracting up to 20% of the area with the highest KAM value, it is possible to extract only the highly distorted areas.
• a measurement point is an area made up of any number of pixels. The size of the pixels that make up the measurement point is preferably 0.1 to 1.0 ⁇ m in order to accurately determine the KAM value.
• the region with 20% of the KAM value from the high side is found as follows. First, a histogram showing the frequency distribution of the KAM value in the cross section of interest is created. This histogram shows the frequency distribution of the KAM value in the cross section. Next, this histogram is converted into a cumulative histogram. Then, in this cumulative histogram, the range from the high KAM value side to 20% of the cumulative relative frequency (0-20%) is determined. Then, the region (a) with KAM values in this range is defined (mapped) on the cross section as the "region with 20% of the KAM value from the high KAM value side.” In other words, the area of the region (a) defined in this way is Ssab. Next, in the cross section, the region (b) of the ⁇ 411 ⁇ crystal grains is defined, and the region (c) where the regions (a) and (b) overlap is found. The area of the region (c) defined in this way is Ssabc.
• Sallc, Sallg, Ssabc, etc. do not strictly indicate the area of the crystal grains in each orientation, but include, for example, the areas of orientations that allow a deviation (tolerance) of up to 10° from each orientation.
• the area ratio of crystal grains in the target crystal orientation is the area ratio of crystal grains that have a crystal orientation within ⁇ 10° of the target crystal orientation.
• the KAM value can be calculated by analyzing an image of the cross section of the sample using software such as OIM Analysis.
• the highest KAM value is automatically assigned by the software.
• the side with a high KAM value means the side with the highest KAM value in the frequency distribution of KAM values.
• the range that occupies 20% of the cumulative relative frequency from the high KAM value side is the range of cumulative relative frequency from 1 to 0.8.
• the metal structure to be specified is specified in a cross section parallel to the sheet surface of the steel sheet, and is specified by the following procedure.
• the plate is polished so that the 1/2 thickness position is exposed, and the polished surface (polished surface polished 1/2 from the plate surface side of the steel plate) is observed by EBSD (Electron Back Scattering Diffraction) using an SEM at an acceleration voltage of 25 kV and a magnification of 1000 times.
• the observation field is 500 ⁇ m ⁇ 500 ⁇ m. Observation may be performed at several locations divided into several small sections.
• the step interval during measurement is 0.3 ⁇ m.
• the following types of areas and KAM (Kernel Average Misorientation) values are obtained from the EBSD observation data by a general method.
• the area of each orientation can be obtained by calculating the IPF (Inverse Pole Figure) from the EBSD observation field of view.
• the KAM value can be obtained by calculating the orientation difference between measurement points using software such as OIM Analysis.
• the tolerance for entering the KAM value is set to an orientation difference of 5° or less with adjacent pixels using OIM Analysis 7.3, and the average value of the calculated orientation difference between the nearest ( 1st neighbor) measurement points is used as the KAM value. Note that the setting of "Set zero point kernel to maximum misorientations" is left as the default and checked.
• Sac satisfies Sac>0.120.
• Sac>Sag indicates that the proportion of ⁇ 411 ⁇ crystal grains is greater than that of ⁇ 110 ⁇ crystal grains. In the annealing after the skin pass, both ⁇ 411 ⁇ crystal grains and ⁇ 110 ⁇ crystal grains tend to grow. Here, since the magnetic properties of ⁇ 411 ⁇ crystal grains in the 45° direction from the rolling direction are superior to those of ⁇ 110 ⁇ crystal grains, it is more preferable to increase the number of ⁇ 411 ⁇ crystal grains.
• Sac>Sbc means that there are relatively few areas of high strain in the ⁇ 411 ⁇ crystal grains. It is known that during annealing after skin pass rolling, grains with less strain encroach on grains with more strain. Therefore, this inequality means that ⁇ 411 ⁇ crystal grains are more likely to grow.
• the area ratio Sag of ⁇ 110 ⁇ crystal grains is less than 0.05. If the area ratio Sag of ⁇ 110 ⁇ crystal grains is 0.05 or more, excellent magnetic properties cannot be obtained.
• the reason for Sbc>Sag is that the magnetic properties in the 45° direction from the rolling direction are improved when the proportion of ⁇ 411 ⁇ crystal grains in the high strain region is greater than the proportion of ⁇ 110 ⁇ crystal grains.
• the non-oriented electrical steel sheet according to this embodiment refers to a final annealed sheet, and of the three directions at angles of 0°, 45°, and 90° with the rolling direction, the magnetic properties in the 45° direction are the best.
• the magnetic properties in the 45° direction are the average value of the magnetic properties in the two directions at angles of +45° and -45° with the rolling direction.
• the magnetic flux density B50 in the rolling direction is 1.58 T or more, and the magnetic flux density B50 in the direction at 45° to the rolling direction is 1.70 T or more.
• the magnetic flux density B50 value in the rolling direction is B50L
• the magnetic flux density B50 value in a direction at 45° to the rolling direction is B50D
• the magnetic flux density B50 value in a direction at 90° to the rolling direction is B50C
• anisotropy in the magnetic flux density is observed, in which B50D is relatively high, followed by B50L , and B50C is relatively low.
• the magnetic flux density can be measured by cutting a 55 mm square sample at 45°, 0°, etc., relative to the rolling direction and using a single sheet magnetic measuring device.
• the non-oriented electrical steel sheet according to the present embodiment is obtained by a production method including a hot rolling step, a cold rolling step, an intermediate annealing step, a skin pass rolling step, and a final annealing step. Preferred conditions for each step will now be described.
• the Ar3 temperature is the transformation temperature Ar3 (°C) defined by the above formula (1).
• Hot rolling process In the hot rolling process, hot rolling is performed on the steel material satisfying the above-mentioned chemical composition to produce a hot rolled steel sheet.
• 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 chemical composition does not change substantially in subsequent processes).
• the molten steel is cast into 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 it is preferable to heat the steel material having the above-mentioned chemical composition to 1000 to 1200° C.
• the steel material is charged into a heating furnace or a soaking furnace and heated in the furnace.
• the holding time at the above-mentioned heating temperature in the heating furnace or the soaking furnace is not particularly limited, but is, for example, 30 to 200 hours.
• Hot rolling In the rolling process, multiple passes of rolling are performed on the steel material heated in the heating process to produce hot-rolled steel plate.
• “pass” means that the steel plate passes through one rolling stand having a pair of work rolls and is reduced.
• 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, or by reverse rolling using a pair of work rolls to perform multiple passes. From the viewpoint of productivity, it is preferable to perform multiple rolling passes using a tandem rolling mill.
• the above-mentioned steel material is heated and hot rolled.
• the steel material is, for example, a slab produced by normal continuous casting.
• the slab is heated to the Ar 3 temperature or higher, which is a temperature range in which the steel structure becomes a ⁇ phase.
• Hot rolling is started in a temperature range in which the steel structure becomes a ⁇ phase (hereinafter, this temperature range may be described as a ⁇ range), and is performed in the ⁇ range except for a necessary number of passes including the final pass of the finish rolling, and is completed by performing a necessary number of passes including the final pass in a temperature range in which the ⁇ phase exists in the steel structure (hereinafter, this temperature range may be described as an ⁇ range).
• the front to middle stages of rough rolling and finish rolling are performed in the ⁇ range, and the rear stage of finish rolling is performed in the ⁇ range.
• the total reduction in the temperature range from the Ar 3 temperature or higher to Ar 3 +20°C or lower immediately before the final rolling in the ⁇ range is set to 10% or more.
• the rolling reduction in the temperature range of the finish rolling temperature FT or higher and lower than the Ar 3 temperature is set to 15% or more in total, taking into consideration the case where rolling is performed in multiple passes.
• the finish rolling temperature FT refers to the surface temperature of the hot-rolled steel sheet immediately after finish rolling.
• the lower limit of the finish rolling temperature FT is not particularly limited, but is set to, for example, Ar3 temperature -100°C or more.
• Rolling in a temperature range above Ar3 + 20°C just before the final rolling in the ⁇ region has almost no effect on the grain size of the deformed ⁇ grains before the phase transformation, and coarse deformed ⁇ grains are formed after the transformation, which is unrelated to the accumulation in the ⁇ 411 ⁇ crystal orientation in the final product. If the rolling reduction ratio in the temperature range from Ar3 temperature to Ar3 + 20°C immediately before the final rolling in the ⁇ region is less than 10%, the accumulation of strain in the processed ⁇ grains before the phase transformation is insufficient, coarse processed ⁇ grains are formed, and accumulation in the ⁇ 411 ⁇ crystal orientation in the final product is difficult.
• the rolling reduction ratio in the temperature range from Ar3 temperature to Ar3 + 20°C is preferably 15% or more.
• the total rolling reduction ratio there is no upper limit for the total rolling reduction ratio, but since a reduction ratio exceeding 40% places too much strain on the rolling machine, it is preferable to set the upper limit at 40%, and more preferably at 30% or less. If the total reduction in the temperature range from the finish rolling temperature FT to the Ar3 temperature in the final ⁇ region is less than 15%, the processed ⁇ grains after phase transformation from the processed ⁇ grains cannot sufficiently accumulate processing strain in the ⁇ region, and accumulation in the ⁇ 411 ⁇ crystal orientation in the final product is difficult.
• the reduction in the temperature range from the finish rolling temperature FT to the Ar3 temperature is preferably 20% or more.
• the lower limit temperature for rolling in the ⁇ region is not particularly limited, but since a lower rolling temperature increases the load on the rolling mill, it is preferable to set the lower limit temperature to 600° C. or higher.
• the rolling temperature may fluctuate above or below the specified judgment temperature ( Ar3 temperature, or Ar3 + 20°C) during the rolling pass due to the competition between the temperature drop caused by roll contact and cooling lubricant and the temperature rise caused by processing. In this embodiment, such a situation is handled as follows.
• the temperature on the entry side is TPI (°C)
• the thickness on the entry side is TCI (mm)
• the temperature on the exit side is TPO (°C)
• the thickness on the exit side is TCO (mm)
• the above assumption also assumes that the exit temperature of the rolling pass is higher than the entry temperature.
• the exit temperature of the rolling pass is higher than the entry temperature.
• the temperature fluctuations on either side of the Ar 3 temperature may occur over multiple passes.
• the rolling conditions in the ⁇ region are the "final rolling process in the ⁇ region".
• the rolling conditions in the ⁇ region are the “rolling process in the ⁇ region immediately before the above-mentioned "final rolling process in the ⁇ region".
• the rolling temperature after starting hot rolling in the ⁇ region changes as follows: ⁇ region (start of hot rolling) ⁇ ⁇ region 1 ⁇ ⁇ region 1 ⁇ ⁇ region 2 ⁇ ⁇ region 2 ⁇ ⁇ region 3 (end of hot rolling), if the ⁇ region 3 and the ⁇ region 2 meet the conditions of this embodiment, it is possible to obtain the disclosed steel sheet.
• the rolling temperature in each pass can be measured, for example, by a thermometer installed at the entry or exit of the rolling stand that performs the reduction of the target pass. It is not necessary to install thermometers at the entry and exit of all rolling stands whose temperature range falls within the range disclosed herein, and the rolling temperature at intermediate rolling stands may be calculated from the actual temperatures of thermometers appropriately installed before and after them. Rather, in current hot rolling, control using such calculated temperatures is usually performed.
• the finish rolling temperature FT is preferably set to be lower than the Ar3 temperature.
• the hot-rolled sheet is coiled without annealing.
• the temperature during coiling is preferably greater than 250°C and less than 600°C.
• the crystal structure before cold rolling can be refined, and the effect of imparting ⁇ 411 ⁇ crystal orientation, which has excellent magnetic properties, during bulging can be obtained. From this perspective, the temperature during coiling is more preferably 350°C to 550°C, and even more preferably 400°C to 480°C.
• Cold rolling process In the cold rolling process, the hot rolled steel sheet after the cooling process is cold rolled to obtain a cold rolled steel sheet. Specifically, after hot rolling, the hot rolled steel sheet is pickled and then cold rolled.
• the reduction In the cold rolling, the reduction is preferably 80% to 92%.
• the lower limit of the reduction may be 83% or more, and may further be 85% or more.
• the upper limit of the reduction may be 90% or less. Note that the higher the reduction, the easier it is for crystal grains having the ⁇ 411 ⁇ crystal orientation to grow due to subsequent bulging, but the sheet shape deteriorates and operation becomes more difficult.
• intermediate annealing process In the intermediate annealing step, intermediate annealing is performed on the cold-rolled steel sheet.
• the temperature of intermediate annealing is controlled to 650 to less than 700 ° C. If the temperature of intermediate annealing is 700 ° C. or higher, excessive grain growth of crystal grains will make it difficult for the grains to accumulate in the ⁇ 411 ⁇ crystal orientation even if skin-pass rolling and final annealing described later are performed, and the development of ⁇ 110 ⁇ crystal grains will be promoted.
• the temperature of intermediate annealing is preferably 650 ° C. or higher.
• the lower limit of the temperature of intermediate annealing may be 660 ° C. or higher, and may further be 680 ° C. or higher.
• the temperature described here is based on the premise of continuous annealing, and the time of intermediate annealing is preferably in the range of 5 to 120 seconds.
• the annealing temperature range and annealing time range are suitable conditions for allowing the ⁇ 411 ⁇ crystal grains, which have already formed in no small amount by the cold rolling step, to grow appropriately by bulging, and for creating a state in which strain-induced grain growth is likely to occur by the skin-pass rolling and final annealing described below.
• the crystal grains having the ⁇ 411 ⁇ crystal orientation are less likely to accumulate strain due to skin pass rolling, while the crystal grains belonging to the orientation group having the ⁇ 111 ⁇ plane orientation called ⁇ -fiber, such as ⁇ 111 ⁇ 112> and ⁇ 111 ⁇ 110>, tend to accumulate strain, and the crystal grains having the ⁇ 411 ⁇ crystal orientation with less strain in the subsequent annealing are driven by the difference in strain to eat away at these ⁇ -fiber orientation grains.
• This encroachment phenomenon that occurs with the difference in strain as the driving force is called strain induced grain boundary migration (hereinafter, SIBM). It is preferable that the reduction ratio of the skin pass rolling is 5% to less than 20%.
• the reduction rate is less than 5%, the amount of strain is too small, so that the subsequent annealing does not cause strain-induced grain boundary migration (hereinafter, SIBM), and the crystal grains having the ⁇ 411 ⁇ crystal orientation do not grow.
• SIBM strain-induced grain boundary migration
• the reduction rate is 20% or more, the amount of strain becomes too large, and recrystallization nucleation (hereinafter, nucleation) occurs, in which new crystal grains are born from crystal grains having the ⁇ -fiber orientation. In this nucleation, most of the grains born are crystal grains having the ⁇ -fiber orientation, so the magnetic properties deteriorate. From this viewpoint, it is more preferable to set the reduction rate of the skin pass rolling to 8% to 15%.
• non-oriented electrical steel sheet is to have the above-mentioned strain distribution
• the reduction rate RR1 (%) in cold rolling is defined as follows.
• Reduction rate RR1 (%) (1 - thickness after the final pass of cold rolling / thickness before the first pass of cold rolling) x 100
• the reduction ratio RR2 (%) in skin pass rolling is defined as follows.
• Reduction rate RR2 (%) (1 - thickness after the final pass of skin pass rolling / thickness before the first pass of skin pass rolling) x 100
• the steel sheet after the skin pass rolling is subjected to final annealing.
• This final annealing generates SIBM driven by the strain difference for each crystal orientation due to the skin pass rolling, and crystal grains having the ⁇ 411 ⁇ crystal orientation as the object of the present disclosure grow preferentially, increasing the ⁇ 411 ⁇ crystal orientation concentration of the steel sheet.
• the annealing conditions can be appropriately set by a person skilled in the art while checking the occurrence of SIBM, and are not particularly limited, but an example can be annealing at 800°C for 2 hours.
• the non-oriented electrical steel sheet according to this embodiment can be manufactured.
• This final annealing can be performed, for example, at a steel sheet manufacturer after skin pass rolling, in the form of a steel sheet coil or as a cut sheet.
• the steel sheet can be shipped without final annealing, and the motor manufacturer can process the steel sheet into a predetermined shape as a motor core, laminate the steel sheet, and then perform the final annealing in the core shape.
• the final annealing can also be performed as a "stress relief annealing" that is generally performed on motor cores by motor manufacturers. If the steel sheet manufacturer performs the final annealing before shipping, motor manufacturers can use the disclosed steel sheet to obtain good motor characteristics. Also, if the steel sheet manufacturer ships the steel sheet up to skin pass rolling, and the motor manufacturer processes it into a motor core and then performs the final annealing as stress relief annealing, good motor characteristics can also be obtained using the disclosed steel sheet.
• the steel member made of the non-oriented electromagnetic steel sheet according to this embodiment is applied to, for example, the iron core (motor core) of a rotating electric machine.
• the iron core used in the rotating electric machine is produced by cutting out individual flat thin plates from the non-oriented electromagnetic steel sheet according to this embodiment and appropriately stacking these flat thin plates.
• This iron core uses non-oriented electromagnetic steel sheet with excellent magnetic properties, so iron loss is kept low, resulting in a rotating electric machine with excellent torque.
• the steel member made of the non-oriented electromagnetic steel sheet according to this embodiment can also be applied to products other than the iron core of a rotating electric machine, such as the iron core of a linear motor or a stationary machine (reactor or transformer).
• non-oriented electrical steel sheet according to the embodiment of the present disclosure will be specifically described with reference to an example.
• the example shown below is merely one example of the non-oriented electrical steel sheet according to the embodiment of the present disclosure, and the non-oriented electrical steel sheet according to the present disclosure is not limited to the example below.
• Molten steel was cast to produce ingots having the components shown in Table 1 below.
• Table 1 "Co, etc.” indicates the respective contents of Co, Pt, Pb, and Au.
• the produced ingots were then subjected to a hot rolling process, a cold rolling process, an intermediate rolling process, a skin pass rolling process, and a final annealing process under the conditions shown in Table 2.
• the final annealing in the final annealing process was performed at the temperature shown in Table 2 for 2 hours. The following characteristics were then examined using the above-mentioned method.
• Transformation temperature Ar3 (°C) ⁇ Plate thickness ⁇ 411 ⁇ grain area ratio Sac Area ratio of ⁇ 110 ⁇ crystal grains Sag
• the cut test piece was processed to reduce the thickness to 1/2, and the processed surface (the polished surface obtained by polishing the steel sheet to 1/2 from the sheet surface side of the steel sheet) was observed by EBSD (step interval: 0.3 ⁇ m) in the above-mentioned manner.
• the areas of the orientation grains of the types shown in Table 3 were obtained by EBSD observation using OIM Analysis 7.3.
• 55 mm square specimens were taken from the steel sheets after final annealing as measurement samples. At this time, a specimen with one side parallel to the rolling direction and a specimen with one side inclined at 45 degrees to the rolling direction were taken.
• the specimens were taken using a shearing machine. Then, the magnetic flux density B 50L in the rolling direction, the magnetic flux density B 50D in the 45° direction with respect to the rolling direction, and the magnetic flux density B 50C in the 90° direction with respect to the rolling direction were measured in accordance with JIS C2556 (2015). The measurement results are shown in Table 3.
• the rollability was evaluated as follows. In a 1 m long region in the longitudinal direction, centered on a position 10 m in the longitudinal direction from the outermost longitudinal tip of the cold-rolled sheet coil (top part), a position 1/2 the total length of the coil in the longitudinal direction from the outermost longitudinal tip of the coil (middle part), and a position 10 m in the longitudinal direction from the innermost longitudinal tip of the coil (bottom part), if cracks having a length of 1 cm or more were present in a total of two or more places on both end faces in the sheet width direction of the coil, the evaluation was given as "N", and otherwise "Y".
• the cold-rolled coil was used as the evaluation target for rollability, but when evaluating a steel sheet cut out from a cold-rolled coil, both end faces in the sheet width direction may be observed in three or more different positions in the longitudinal direction (rolling direction) of the steel sheet in the same manner as described above. For example, it is sufficient to observe in a range of about 1/10 of the entire longitudinal length of the steel sheet, centered at positions of about 1/10, 1/2, and 9/10 of the longitudinal length of the steel sheet, and the entire longitudinal length of the steel sheet may be 1 m or more.
• the non-oriented electrical steel sheet according to the present disclosure has excellent magnetic properties in the direction at 45° from the rolling direction by appropriately controlling the chemical composition, hot rolling conditions, cold rolling conditions, intermediate annealing conditions, skin pass rolling conditions, and final annealing process conditions. There are also no problems with rolling.
• This disclosure provides a non-oriented electrical steel sheet that has no problems with rolling and can achieve excellent magnetic properties in the 45° direction from the rolling direction, making it extremely useful in industry.

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