# US 12,215,410 B2 · Grain oriented electrical steel sheet, forming method for insulation coating of grain oriented electrical steel sheet, and producing method for grain oriented electrical steel sheet > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,215,410 B2 - Document ID: US12215410B2 - Status: Granted - Kind: B2 - Application number: 17/422,517 - Filed: 2020-01-16 - Published: 2022-03-24 - Granted: 2025-02-04 - Earliest claimed: 2019-01-16 - Assignees: Nippon Steel Corporation - Applicants: Nippon Steel Corporation - Inventors: Ichiro Tanaka; Takashi Kataoka; Kazutoshi Takeda; Tomoya Suenaga; Yuki Kunita - Web page: https://patentgrep.com/patent/US12215410B2 ## CPC - C21D 8/1233: {Cold rolling} - C22C 38/06: containing aluminium - C21D 1/26: Methods of annealing - C21D 3/04: Decarburising - C21D 8/02: during manufacturing of plates or strips (C21D8/12 takes precedence) - C21D 8/0226: {Hot rolling} - C21D 8/0236: {Cold rolling} - C21D 8/1255: {with diffusion of elements, e.g. decarburising, nitriding} - C21D 8/1272: {Final recrystallisation annealing} - C21D 8/1283: {Application of a separating or insulating coating} - C21D 8/1288: {Application of a tension-inducing coating} - C21D 9/46: for sheet metals - C22C 38/001: {containing N} - C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60} - C22C 38/004: {Very low carbon steels, i.e. having a carbon content of less than 0,01%} - C22C 38/02: containing silicon - C22C 38/04: containing manganese - C22C 38/16: containing copper - C22C 38/34: with more than 1.5% by weight of silicon - C22C 38/60: containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur - C23C 22/08: Orthophosphates - C23C 22/74: for obtaining burned-in conversion coatings - C23C 28/04: only coatings of inorganic non-metallic material - C23G 1/08: Iron or steel - C23G 1/081: {solutions containing H2SO4} - C23G 1/086: {solutions containing HF} - H01F 1/147: Alloys characterised by their composition {(treatment thereof for enhancing their electromagnetic properties C21D8/12)} - H01F 1/18: with insulating coating - C21D 6/008: {containing Si} - C21D 2201/05: Grain orientation - C22C 38/008: {containing tin} - C22C 2202/02: Magnetic - H01F 1/14783: {with insulating coating} - 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 (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B) - C22C: ALLOYS (treatment of alloys C21D, C22F) - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract A grain oriented electrical steel sheet includes a base steel sheet, an oxide layer, and a tension-insulation coating. When the iron oxide layer is analyzed by a fourier transform infrared spectroscopy, an absorbance A650 at 650 cm−1 and an absorbance A1250 at 1250 cm−1 satisfy 0.2≤A650/A1250≤5.0. Moreover, a magnetic flux density B8 in a rolling direction of the grain oriented electrical steel sheet is 1.90 T or more. ## Claims ### Claim 1 A grain oriented electrical steel sheet without a forsterite film characterized in that the grain oriented electrical steel sheet comprises: a base steel sheet; an oxide layer arranged in contact with the base steel sheet; and a tension-insulation coating arranged in contact with the oxide layer, wherein the base steel sheet includes, as a chemical composition, by mass %, 2.5 to 4.0% of Si, 0.05 to 1.00% of Mn, 0 to 0.01% of C, 0 to 0.005% of S+Se, 0 to 0.01% of sol.Al, 0 to 0.005% of N, 0 to 0.03% of Bi, 0 to 0.03% of Te, 0 to 0.03% of Pb, 0 to 0.50% of Sb, 0 to 0.50% of Sn, 0 to 0.50% of Cr, 0 to 1.0% of Cu, and a balance consisting of Fe and impurities, the oxide layer is an iron oxide layer, when the iron oxide layer is analyzed by a fourier transform infrared spectroscopy, when A650 is an absorbance of an absorption peak detected at 650 cm−1 in an infrared absorption spectrum, and when A1250 is an absorbance of an absorption peak detected at 1250 cm−1 in the infrared absorption spectrum, the A650 and the A1250 satisfy 0.2≤A650/A1250≤5.0, and a magnetic flux density B8 in a rolling direction of the grain oriented electrical steel sheet is 1.90 T or more. ### Claim 2 (depends on 1) The grain oriented electrical steel sheet according to claim 1, wherein an average thickness of the iron oxide layer is 200 to 500 nm. ### Claim 3 A forming method for an insulation coating of a grain oriented electrical steel sheet without a forsterite film characterized in that the forming method for the insulation coating includes an insulation coating forming process of forming a tension-insulation coating on a steel substrate, wherein, in the insulation coating forming process, a solution for forming the tension-insulation coating is applied to an oxide layer of the steel substrate and the solution is baked, wherein the steel substrate includes a base steel sheet and the oxide layer arranged in contact with the base steel sheet, the base steel sheet includes, as a chemical composition, by mass %, 2.5 to 4.0% of Si, 0.05 to 1.00% of Mn, 0 to 0.01% of C, 0 to 0.005% of S+Se, 0 to 0.01% of sol. Al, 0 to 0.005% of N, 0 to 0.03% of Bi, 0 to 0.03% of Te, 0 to 0.03% of Pb, 0 to 0.50% of Sb, 0 to 0.50% of Sn, 0 to 0.50% of Cr, 0 to 1.0% of Cu, and a balance consisting of Fe and impurities, the oxide layer is an iron oxide layer, and when the iron oxide layer is analyzed by a fourier transform infrared spectroscopy, when A650 is an absorbance of an absorption peak detected at 650 cm−1 in an infrared absorption spectrum, and when A1250 is an absorbance of an absorption peak detected at 1250 cm−1 in the infrared absorption spectrum, the A650 and the A1250 satisfy 0.2≤A650/A1250≤5.0. ### Claim 4 (depends on 3) The forming method for the insulation coating of the grain oriented electrical steel sheet according to claim 3, wherein an average thickness of the iron oxide layer is 200 to 500 nm. ### Claim 5 (depends on 1) A producing method for the grain oriented electrical steel sheet without a forsterite film of claim 1 characterized in that the producing method includes a hot rolling process of heating and thereafter hot-rolling a steel piece to obtain a hot rolled steel sheet, a hot band annealing process of optionally annealing the hot rolled steel sheet to obtain a hot band annealed steel sheet, a cold rolling process of cold-rolling the hot rolled steel sheet or the hot band annealed steel sheet by cold-rolling once or by cold-rolling a plurality of times with an intermediate annealing to obtain a cold rolled steel sheet, a decarburization annealing process of decarburization-annealing the cold rolled steel sheet to obtain a decarburization annealed steel sheet, a final annealing process of applying an annealing separator to the decarburization annealed steel sheet and thereafter final-annealing the decarburization annealed steel sheet to obtain a final annealed steel sheet, an oxidizing process of conducting a washing treatment, a pickling treatment, and a heat treatment in turn for the final annealed steel sheet to obtain an oxidized steel sheet, an insulation coating forming process of applying a solution for forming a tension-insulation coating to a surface of the oxidized steel sheet and of baking the solution, wherein, in the hot rolling process, the steel piece includes, as a chemical composition, by mass %, 2.5 to 4.0% of Si, 0.05 to 1.00% of Mn, 0.02 to 0.10% of C, 0.005 to 0.080% of S+Se, 0.010 to 0.07% of sol.Al, 0.005 to 0.020% of N, 0 to 0.03% of Bi, 0 to 0.03% of Te, 0 to 0.03% of Pb, 0 to 0.50% of Sb, 0 to 0.50% of Sn, 0 to 0.50% of Cr, 0 to 1.0% of Cu, and a balance consisting of Fe and impurities, and wherein, in the oxidizing process, as the washing treatment, a surface of the final annealed steel sheet is washed, as the pickling treatment, the final annealed steel sheet is pickled using a sulfuric acid of 5 to 20 mass %, and as the heat treatment, the final annealed steel sheet is held in a temperature range of 700 to 850° C. for 10 to 50 seconds in an atmosphere where an oxygen concentration is 5 to 21 volume % and a dew point is ˜ 10 to 30° C. ### Claim 6 (depends on 5) The producing method for the grain oriented electrical steel sheet according to claim 5, wherein, in the final annealing process, the annealing separator includes MgO of 60 mass % or more, and a forsterite film formed on a surface is removed by grinding or pickling the surface of the final annealed steel sheet after final annealing. ### Claim 7 (depends on 5) The producing method for the grain oriented electrical steel sheet according to claim 5, wherein, in the decarburization annealing process, when S1 is an average heating rate in units of ° C./second in a temperature range of 500° C. or more and less than 600°° C. during raising a temperature of the cold rolled steel sheet and when S2 is an average heating rate in units of ° C./second in a temperature range of 600°° C. or more and 700° C. or less during raising the temperature of the cold rolled steel sheet, the S1 and the S2 satisfy 300≤S1≤1000, 1000≤S2≤3000, and 1.0