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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 by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1272—Final recrystallisation annealing
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  • C21D10/00—Modifying the physical properties by methods other than heat treatment or deformation
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  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/008—Heat treatment of ferrous alloys containing Si
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  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular fabrication or treatment of ingot or slab
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  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
  • C21D8/1222—Hot rolling
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  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
  • 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 by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1255—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest with diffusion of elements, e.g. decarburising, nitriding
• • 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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1261—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest 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 by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1277—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular surface treatment
  • C21D8/1283—Application of a separating or insulating coating
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1294—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a localized treatment
• • C—CHEMISTRY; METALLURGY
  • 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
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/002—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
  • C22C38/008—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
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
• • 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
  • H01F1/14783—Fe-Si based alloys in the form of sheets with insulating coating
• • 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
  • H01F1/18—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 with insulating coating
• • 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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
  • C21D1/76—Adjusting the composition of the atmosphere
• • 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 method for manufacturing a grain-oriented electrical steel sheet with low iron loss and high magnetic flux density.
• a grain-oriented electrical steel sheet is a soft magnetic material used as a core material for transformers and generators, and has a crystal structure in which the ⁇ 001> orientation, which is the easy magnetization axis of iron, is highly aligned in the rolling direction of the steel sheet. is characteristic.
• Such a texture causes secondary recrystallization in the finish annealing in the manufacturing process of grain-oriented electrical steel sheets, and the crystal grains of ⁇ 110 ⁇ ⁇ 001> orientation called Goss orientation are preferentially large. Formed by growing.
• Patent Document 1 discloses a method of using MnS or MnSe as an inhibitor
• Patent Document 2 discloses a method of using AlN or MnS as an inhibitor, both of which have been put into industrial practice.
• the method using these inhibitors requires heating the slab to an extremely high temperature of 1300° C. or higher, but is a very effective method for stably developing secondary recrystallization.
• Patent Document 3 discloses a method of adding Pb, Sb, Nb or Te
• Patent Document 4 discloses Zr, Ti, B, Nb, Ta, V
• a method of adding Cr and Mo is disclosed.
• the steel material contains 0.010 to 0.060% of acid-soluble Al (sol. Al)
• the slab heating temperature is suppressed to a low temperature
• the decarburization annealing process is performed under an appropriate atmosphere.
• a method has also been proposed in which (Al,Si)N is precipitated during secondary recrystallization in final annealing and used as an inhibitor by performing a nitriding treatment.
• Patent Document 6 and the like disclose a technique for developing Goss-oriented grains by secondary recrystallization using a steel material that does not contain inhibitor-forming components.
• This technology eliminates impurities such as inhibitor-forming components as much as possible and reveals the dependence of the grain boundary energy of the crystal grain boundary during primary recrystallization on the grain boundary misorientation angle.
• This is a technique for secondary recrystallization of Goss-oriented grains, and its effect is also called texture inhibition.
• This method does not require a treatment to purify the inhibitor-forming components, so there is no need to raise the temperature of the final annealing.Furthermore, since it does not require fine dispersion of the inhibitor, it is indispensable for solid solution of the inhibitor-forming components. There is no need for high-temperature slab heating, which is a great advantage in terms of cost and manufacturing.
• Patent Document 7 by limiting the amount of N as AlN in the hot-rolled sheet to 25 mass ppm or less and heating to 700 ° C. or higher at a heating rate of 80 ° C./s or higher during decarburization annealing, low iron A technique for obtaining a loss-oriented electrical steel sheet is disclosed.
• Patent Document 8 when decarburizing and annealing a cold-rolled sheet rolled to the final thickness, in a non-oxidizing atmosphere with a P H2O /P H2 of 0.2 or less, 700 ° C. at 100 ° C./s or more.
• a technique for obtaining a grain-oriented electrical steel sheet with low iron loss by rapid heating to the above temperature is disclosed.
• the inventors diligently studied the cause of the decrease in magnetic flux density due to rapid heating during decarburization annealing. As a result, when increasing the temperature rise rate in the heating process of the decarburization annealing, the temperature range where secondary recrystallization occurs in the final annealing is gradually heated, and only the crystal grains in the Goss orientation are grain-grown, thereby increasing the magnetic flux density
• the present inventors have found that the iron loss can be reduced without causing a decrease in the iron loss, and have developed the present invention.
• the present invention based on the above findings contains C: 0.002 to 0.10 mass%, Si: 2.0 to 8.0 mass% and Mn: 0.005 to 1.0 mass%, and further as an inhibitor-forming component
• the hot-rolled sheet After the hot-rolled sheet is subjected to hot-rolled sheet annealing, it is cold-rolled once or cold-rolled twice or more with intermediate annealing to obtain a cold-rolled sheet having a final thickness, and the cold-rolled sheet is subjected to primary
• the surface of the steel sheet After performing decarburization annealing that also serves as recrystallization annealing, the surface of the steel sheet is coated with an annealing separator, and after performing finish annealing, when forming an insulating coating, the temperature is 500 to 700 in the heating process of the decarburization annealing. While rapidly heating at 100 to 1000 ° C./s between ° C., in the section of 860 to 970 ° C.
• the steel material used in the method for producing a grain-oriented electrical steel sheet of the present invention further includes Ni: 0.01 to 1.50 mass%, Cr: 0.01 to 0.50 mass%, Cu: 0 .005 to 1.000 mass%, P: 0.005 to 0.500 mass%, Sb: 0.005 to 0.500 mass%, Sn: 0.005 to 0.500 mass%, Bi: 0.005 to 0.500 mass% %, Mo: 0.005 to 0.500 mass%, Nb: 0.0010 to 0.0100 mass%, Ta: 0.001 to 0.010 mass% and Ti: at least one of 0.001 to 0.0100 mass% It is characterized by containing seeds.
• the method for producing a grain-oriented electrical steel sheet according to the present invention is characterized in that grooves are formed in the surface of the steel sheet in a direction intersecting the rolling direction in any of the steps after the cold rolling, and magnetic domain refining treatment is performed. do.
• the method for producing a grain-oriented electrical steel sheet according to the present invention is characterized in that the surface of the steel sheet coated with the insulating coating is subjected to a magnetic domain refining treatment by irradiating an electron beam or a laser beam in a direction intersecting the rolling direction. do.
• the heating rate in the secondary recrystallization temperature range in the final annealing is optimized, and the secondary recrystallization of grains deviated from the Goss orientation is suppressed, so even when rapid heating is performed during decarburization annealing. , it becomes possible to manufacture a grain-oriented electrical steel sheet with low core loss without causing a decrease in magnetic flux density.
• the hot-rolled sheet was subjected to hot-rolled sheet annealing at 1100°C for 30 seconds, followed by first cold rolling to an intermediate sheet thickness of 1.8 mm, followed by intermediate annealing at 1020°C for 100 seconds. After that, it was cold-rolled for the second time by a reverse rolling mill to finish a cold-rolled sheet having a final sheet thickness of 0.23 mm.
• the cold-rolled sheet was subjected to decarburization annealing, which also served as primary recrystallization annealing, at 880° C. for 60 seconds in a moist atmosphere of 50 vol % H 2 -50 vol % N 2 . At this time, the heating rate between 500 and 700° C.
• annealing separator mainly composed of MgO was applied to the surface of the steel sheet, and the steel sheet wound into a coil was heated to 900°C at a rate of 25°C/hr in an N2 atmosphere, and held at the above temperature for 20 hours. After that, the temperature was raised to 970° C. at 25° C./hr, and further heated to 1180° C. at 25° C./hr in a mixed atmosphere of H 2 : 50 vol %-N 2 : 50 vol%. A final annealing was performed by holding the temperature for 5 hours and performing a purification treatment.
• test piece was taken from the steel plate after the finish annealing thus obtained, and the iron loss W 17/50 (iron loss when 1.7 T was excited at a frequency of 50 Hz) and the magnetic flux density B 8 (magnetizing force 800 A /m) was measured by the method described in JIS C 2550.
• the test pieces were taken from three locations, both ends and the center of the product coil, and the worst (highest) iron loss value and lowest (worse) magnetic flux density value were taken as representative values of the coil. The results of the above measurements are shown in Table 1 below.
• the temperature increase rate between 500 and 700°C in the heating process of decarburization annealing is set to 200°C/s (constant), and the temperature increase rate between 860 and 970°C in the heating process of finish annealing is varied as shown in Table 2.
• the iron loss W 17/50 and the magnetic flux density B 8 were measured in the same manner as above. The results of the above measurements are shown in Table 2 below. From this result, it is found that there is a suitable range for the rate of temperature increase in the final annealing, in which both low iron loss and high magnetic flux density can be achieved, specifically 0.5 to 4.0° C./hr. rice field.
• the inventors consider as follows.
• the heating rate of decarburization annealing is increased, the Goss orientation in the primary recrystallized structure and the recrystallized grains in the vicinity thereof increase.
• the increased Goss orientation and the primary recrystallized grains in the vicinity thereof undergo secondary recrystallization in the final annealing, resulting in a secondary recrystallized structure with fine grains.
• C 0.002 to 0.10 mass% If C is less than 0.002 mass%, the grain boundary strengthening effect of C may be lost, cracking may occur in the slab, which may interfere with production or cause surface defects. On the other hand, if it exceeds 0.10 mass%, it becomes difficult to reduce C to 0.005 mass% or less at which magnetic aging does not occur during decarburization annealing. Therefore, C should be in the range of 0.002 to 0.10 mass%. It is preferably in the range of 0.010 to 0.080 mass%.
• Si 2.0 to 8.0 mass%
• Si is an essential component for increasing the specific resistance of steel and reducing iron loss. If it is less than 2.0 mass%, the above effect is not sufficient, while if it exceeds 8.0 mass%, workability decreases. and difficult to roll. Therefore, Si should be in the range of 2.0 to 8.0 mass%. It is preferably in the range of 2.5 to 4.5 mass%.
• Mn 0.005 to 1.0 mass% Mn improves the hot workability of steel, and should be contained in an amount of 0.005 mass% or more. On the other hand, if it exceeds 1.0 mass %, the magnetic flux density of the product sheet will decrease. Therefore, Mn should be in the range of 0.005 to 1.0 mass%. It is preferably in the range of 0.02 to 0.20 mass%.
• Components other than the above C, Si and Mn must contain inhibitor-forming components necessary for developing secondary recrystallization in the final annealing.
• AlN-based inhibitor when used as the inhibitor, it is necessary to contain Al and N in the ranges of Al: 0.010 to 0.050 mass% and N: 0.003 to 0.020 mass%, respectively. be.
• AlN-based and MnS/MnSe-based inhibitors may be used in combination. ⁇ 0.030 mass% and/or Se: 0.003 to 0.030 mass% should be contained.
• Al 0.013 to 0.025 mass%
• N 0.005 to 0.010 mass%
• S 0.004 to 0.015 mass%
• Se 0.005 to 0.020 mass%
• the balance other than the above components is Fe and unavoidable impurities.
• Ni 0.01 to 1.50 mass%, Cr: 0.01 to 0.50 mass%, Cu: 0.005 to 1.000 mass% , P: 0.005 to 0.500 mass%, Sb: 0.005 to 0.500 mass%, Sn: 0.005 to 0.500 mass%, Bi: 0.005 to 0.500 mass%, Mo: 0.005 ⁇ 0.500 mass%, Nb: 0.0010 to 0.0100 mass%, Ta: 0.001 to 0.010 mass% and Ti: one or more selected from 0.001 to 0.0100 mass% It may be contained as appropriate.
• a method for manufacturing the grain-oriented electrical steel sheet of the present invention will be described.
• a steel material (slab) having the chemical composition described above is heated to a predetermined temperature, hot-rolled into a hot-rolled sheet, and hot-rolled into the hot-rolled sheet.
• the cold-rolled sheet is cold-rolled once or cold-rolled twice or more with intermediate annealing to obtain a cold-rolled sheet having a final thickness, and the cold-rolled sheet is decarburized by performing primary recrystallization annealing.
• the steel sheet is annealed, coated with an annealing separator on the steel sheet surface, then finished annealed, and coated with an insulating coating.
• the steel material is preferably produced by melting steel adjusted to the above chemical composition by a generally known refining process, and by continuous casting or ingot casting-slabbing rolling.
• a thin slab with a thickness of 100 mm or less may be produced by direct casting.
• the steel slab is heated to a temperature of 1300°C or higher and 1400°C or lower, and then subjected to hot rolling. If the slab heating temperature is less than 1300° C., the inhibitor-forming component remains undissolved, resulting in unstable secondary recrystallization and insufficient magnetic properties. On the other hand, if the temperature exceeds 1400° C., scale loss increases and surface defects occur. It is preferably in the range of 1310-1375°C.
• the hot rolling conditions are not particularly limited as long as they are normal hot rolling conditions for grain-oriented electrical steel sheets. Also, in the case of thin slabs, hot rolling may be omitted.
• hot-rolled sheet after hot rolling is subjected to hot-rolled sheet annealing in order to improve magnetic properties.
• This hot-rolled sheet baking may be performed under generally known conditions, and there is no particular limitation.
• the hot-rolled sheet after the hot rolling is pickled and descaled, and then subjected to one ordinary cold rolling or two or more cold rollings with intermediate annealing to obtain a final thickness (product sheet thickness) cold-rolled sheet.
• the cold-rolled sheet having the final thickness is subjected to decarburization annealing that also serves as primary recrystallization annealing to obtain a preferable primary recrystallization structure, and the C content in the steel sheet is 0.0050 mass% or less, which does not cause magnetic aging.
• the heating rate between 500°C and 700°C in the heating process of the decarburization annealing be 100 to 1000. Rapid heating as °C/s. If the heating rate is less than 100°C/s, the number of Goss-oriented grains that serve as nuclei for secondary recrystallization in the primary recrystallized structure decreases.
• the soaking conditions for the decarburization annealing are preferably in the range of 800 to 900° C. ⁇ 60 to 300 s in a moist atmosphere.
• the surface of the decarburized and annealed steel sheet is coated with an annealing separator, dried, wound into a coil, subjected to finish annealing while still in the coiled state, and subjected to secondary recrystallization.
• finish annealing the crystal grains of Goss orientation are preferentially grown and the increase of secondary recrystallized grains deviating from the Goss orientation is suppressed. It is important to heat slowly at 5 to 4.0°C/hr. If the heating rate is less than 0.5°C/hr, the orientation sharpness of the Goss orientation in the secondary recrystallized structure decreases.
• the growth rate of the secondary recrystallized grains is excessively increased, and the degree of integration of the secondary recrystallized grains in the Goss orientation is remarkably lowered.
• it is in the range of 0.7 to 2.0°C/hr.
• the time for slow heating at 0.5 to 4.0° C./hr as described above should be 10 hours or more to obtain the above effect. It is preferably 20 hours or longer.
• the slow heating section may be part of the temperature range from 860 to 970° C. if the slow heating can be performed for 10 hours or longer.
• the atmosphere in this section is preferably nitrogen, argon, or a mixed atmosphere of nitrogen and argon.
• the temperature is raised to 1150-1250°C, and then purification treatment is performed by maintaining the temperature for 5-20 hours.
• the atmosphere during the purification treatment is preferably hydrogen, but nitrogen or argon can also be used as necessary.
• the heating rate up to the purification treatment temperature is 5° C./hr or more.
• the atmosphere at that time can be nitrogen, argon, or a mixed atmosphere of nitrogen, argon and hydrogen.
• the steel sheet after the finish annealing is subjected to flattening annealing after removing the unreacted annealing separator from the steel sheet surface, and then applying an insulating coating to obtain a product sheet.
• the insulating coating is preferably a tension-applying insulating coating.
• the non-oriented electrical steel sheet of the present invention is preferably subjected to a magnetic domain refining treatment from the viewpoint of further reducing iron loss.
• a conventionally known method can be adopted as a method of magnetic domain refining.
• a method of forming grooves continuously or intermittently in a direction intersecting the rolling direction by etching or the like on the surface of the steel sheet at predetermined intervals in the rolling direction ,
• Employing a method of irradiating the surface of the steel sheet after the insulation coating is continuously or intermittently intersected with the rolling direction with an electron beam or laser beam at predetermined intervals in the rolling direction. can be done.
• the cold-rolled sheet was subjected to decarburization annealing, which also served as primary recrystallization annealing, at 880° C. for 60 seconds in a moist atmosphere of 50 vol % H 2 -50 vol % N 2 .
• the heating rate between 500 and 700° C. during the heating process was set to 700° C./s.
• the surface of the steel sheet was coated with an annealing separator mainly composed of MgO, wound into a coil, and the steel sheet coil was subjected to finish annealing.
• the temperature rising conditions between 860 and 970° C. and the annealing atmosphere in the heating process of the final annealing were changed as shown in Table 3.
• test piece was taken from the steel plate after the finish annealing thus obtained, and the iron loss W 17/50 (iron loss when 1.7 T was excited at a frequency of 50 Hz) and the magnetic flux density B 8 (magnetizing force 800 A /m) was measured by the method described in JIS C 2550.
• the test pieces were taken from three locations, both ends and the center of the product coil, and the highest (worst) iron loss value and lowest (worst) magnetic flux density value were taken as representative values of the coil.
• Table 3 shows that steel sheets with low iron loss and high magnetic flux density are obtained when the heating rate in the 860 to 970° C. section of the final annealing is in the range of 0.5 to 4.0° C./hr.
• Steel slabs having various chemical compositions shown in Table 4 were produced by continuous casting. Then, the slab was heated to a temperature of 1200° C. and hot rolled to finish a hot-rolled sheet having a thickness of 2.4 mm. Next, the hot-rolled sheet was subjected to hot-rolled sheet annealing at 1100° C. for 30 seconds, and then finished into a cold-rolled sheet having a final sheet thickness of 0.23 mm by the first cold rolling. Next, the cold-rolled sheet was subjected to decarburization annealing, which also served as primary recrystallization annealing, at 880° C. for 60 seconds in a moist atmosphere of 50 vol % H 2 -50 vol % N 2 .
• the heating rate between 500 and 700° C. during the heating process was set to 300° C./s.
• the surface of the steel sheet was coated with an annealing separator mainly composed of MgO, and the steel sheet wound into a coil was subjected to finish annealing.
• the heating in the slow heating section from 860 to 970 ° C. is performed by slowly heating between 880 and 940 ° C. at a temperature rising rate of 1.0 ° C./hr for 60 hours in an N 2 atmosphere, and heating at other temperatures.
• the temperature rate was 15°C/hr.
• purification treatment was performed by raising the temperature to 1180° C. at a rate of 25° C./hr in a mixed atmosphere of H 2 : 75 vol %-N 2 : 25 vol %, and maintaining the temperature for 30 hr in an H 2 atmosphere.
• test piece was taken from the steel plate after the finish annealing thus obtained, and the iron loss W 17/50 (iron loss when 1.7 T was excited at a frequency of 50 Hz) and the magnetic flux density B 8 (magnetizing force 800 A /m) was measured by the method described in JIS C 2550.
• the test pieces were taken from three locations, both ends and the center of the product coil, and the highest (worst) iron loss value and lowest (worst) magnetic flux density value were taken as representative values of the coil.
• Table 4 From these results, it can be seen that a grain-oriented electrical steel sheet with low core loss and high magnetic flux density can be stably obtained by using a steel material that satisfies the present invention and applying conditions that conform to the present invention. .

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