# US 12,110,567 B2 · Method for producing grain oriented electrical steel sheet

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- Number: US 12,110,567 B2
- Document ID: US12110567B2
- Status: Granted
- Kind: B2
- Application number: 17/421,820
- Filed: 2020-01-16
- Published: 2022-03-31
- Granted: 2024-10-08
- Earliest claimed: 2019-01-16
- Assignees: Nippon Steel Corporation
- Applicants: Nippon Steel Corporation
- Inventors: Shinsuke Takatani; Yoshiyuki Ushigami
- Web page: https://patentgrep.com/patent/US12110567B2

## CPC

- C21D 1/76: Adjusting the composition of the atmosphere
- C21D 9/46: for sheet metals
- C21D 3/04: Decarburising
- C21D 6/004: {containing Cr and Ni}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C21D 8/1222: {Hot rolling}
- C21D 8/1233: {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 10/00: Modifying the physical properties by methods other than heat treatment or deformation
- 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 38/008: {containing tin}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/08: containing nickel {(C22C38/105 takes precedence)}
- C22C 38/12: containing tungsten, tantalum, molybdenum, vanadium, or niobium
- C22C 38/14: containing titanium or zirconium
- C22C 38/16: containing copper
- C22C 38/24: with vanadium
- C22C 38/32: with boron
- C22C 38/42: with copper
- C22C 38/44: with molybdenum or tungsten
- C22C 38/46: with vanadium
- C22C 38/48: with niobium or tantalum
- C22C 38/50: with titanium or zirconium
- C22C 38/54: with boron
- C22C 38/60: containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
- C23C 22/08: Orthophosphates
- C23C 22/33: containing also phosphates
- C23C 22/74: for obtaining burned-in conversion coatings
- C23G 1/081: {solutions containing H2SO4}
- H01F 1/147: Alloys characterised by their composition {(treatment thereof for enhancing their electromagnetic properties C21D8/12)}
- H01F 1/18: with insulating coating
- C21D 2201/05: Grain orientation
- C22C 2202/02: Magnetic
- H01F 1/14783: {with insulating coating}
- Y02P 10/20: Recycling
- 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
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method for producing a grain oriented electrical steel sheet includes a decarburization annealing process where an oxidation degree PH2O/PH2 is controlled, an annealing separator applying process where a mass ratio of MgO and MCl in an annealing separator is controlled, a final annealing process where an oxidation degree is controlled when atmosphere includes hydrogen or a dew point is controlled when atmosphere consists of inert gas, and an insulation coating forming process where a mass ratio of phosphoric acid and metal compound in insulation coating forming solution is controlled.

## Claims

### Claim 1

A method for producing a grain oriented electrical steel sheet,
the method comprising:
a hot rolling process of hot-rolling a steel piece to obtain a hot rolled steel sheet, the steel piece including, as a chemical composition, by mass %,
0.030 to 0.100% of C,
0.80 to 7.00% of Si,
0.01 to 1.00% of Mn,
0 to 0.060% in total of S and Se,
0.010 to 0.065% of acid soluble Al,
0.004 to 0.012% of N,
0 to 0.30% of Cr,
0 to 0.40% of Cu,
0 to 0.50% of P,
0 to 0.30% of Sn,
0 to 0.30% of Sb,
0 to 1.00% of Ni,
0 to 0.008% of B,
0 to 0.15% of V,
0 to 0.20% of Nb,
0 to 0.10% of Mo,
0 to 0.015% of Ti,
0 to 0.010% of Bi, and
a balance consisting of Fe and impurities;
a cold rolling process of cold-rolling the hot rolled steel sheet to obtain a cold rolled steel sheet;
a decarburization annealing process of decarburization-annealing the cold rolled steel sheet to obtain a decarburization annealed sheet;
an annealing separator applying process of applying and drying an annealing separator including MgO to the decarburization annealed sheet;
a final annealing process of final-annealing the decarburization annealed sheet after applying the annealing separator to obtain a final annealed sheet;
an annealing separator removing process of removing a redundant annealing separator from a surface of the final annealed sheet; and
an insulation coating forming process of forming an insulation coating on the surface of the final annealed sheet,
wherein, in the decarburization annealing process,
PH2O/PH2 which is an oxidation degree of an atmosphere is 0.01 to 0.15, an annealing temperature is 750 to 900° C., and a holding is 10 to 600 seconds,
wherein, in the annealing separator applying process,
the annealing separator further includes MCl which is at least one selected from chlorides of an alkali metal, an alkaline earth metal, and Bi, and MCl/MgO which is a mass ratio of MgO and MCl is 2 to 40%,
wherein, in the final annealing process,
an oxidation degree is 0.00010 to 0.2 when an atmosphere includes hydrogen, or a dew point is 0° C. or less when an atmosphere consists of an inert gas without hydrogen, and
wherein, in the insulation coating forming process,
an insulation coating forming solution in which a phosphoric acid and a metal compound are included and in which a mass ratio of the phosphoric acid to the metal compound is 2:1 to 1:2 is applied and is baked at 600 to 1150° C., and after decreasing a temperature, an insulation coating forming solution in which a phosphate and a colloidal silica are included and in which a metal compound is not included is applied and is baked at 600 to 1150° C., in order to form the insulation coating.

### Claim 2 (depends on 1)

The method for producing the grain oriented electrical steel sheet according to claim 1,
the method including, between the hot rolling process and the cold rolling process,
at least one of a hot band annealing process of annealing the hot rolled steel sheet and a hot band pickling process of pickling the hot rolled steel sheet.

### Claim 3 (depends on 1)

The method for producing the grain oriented electrical steel sheet according to claim 1,
wherein, in the decarburization annealing process, a nitriding treatment is conducted by annealing the cold rolled steel sheet in an atmosphere including ammonia.

### Claim 4 (depends on 1)

The method for producing the grain oriented electrical steel sheet according to claim 1,
the method including, between the cold rolling process and the decarburization annealing process, between the decarburization annealing process and the annealing separator applying process, between the annealing separator removing process and the insulation coating forming process, or after the insulation coating forming process,
a magnetic domain refining process of conducting a magnetic domain refining treatment.

### Claim 5 (depends on 1)

The method for producing the grain oriented electrical steel sheet according to claim 1,
wherein, in the annealing separator removing process, a pickling is conducted after water-washing using an acidic solution whose volume concentration is less than 20%.

### Claim 6 (depends on 1)

The method for producing the grain oriented electrical steel sheet according to claim 1,
wherein, the steel piece includes, as the chemical composition, by mass %, at least one of
0.02 to 0.30% of Cr,
0.05 to 0.40% of Cu,
0.005 to 0.50% of P,
0.02 to 0.30% of Sn,
0.01 to 0.30% of Sb,
0.01 to 1.00% of Ni,
0.0005 to 0.008% of B,
0.002 to 0.15% of V,
0.005 to 0.20% of Nb,
0.005 to 0.10% of Mo,
0.002 to 0.015% of Ti, and
0.001 to 0.010% of Bi.

### Claim 7

A method for producing a grain oriented electrical steel sheet,
the method comprising:
a hot rolling process of hot-rolling a steel piece to obtain a hot rolled steel sheet, the steel piece including, as a chemical composition, by mass %,
0.030 to 0.100% of C,
0.80 to 7.00% of Si,
0.01 to 1.00% of Mn,
0 to 0.060% in total of S and Se,
0.010 to 0.065% of acid soluble Al,
0.004 to 0.012% of N,
0 to 0.30% of Cr,
0 to 0.40% of Cu,
0 to 0.50% of P,
0 to 0.30% of Sn,
0 to 0.30% of Sb,
0 to 1.00% of Ni,
0 to 0.008% of B,
0 to 0.15% of V,
0 to 0.20% of Nb,
0 to 0.10% of Mo,
0 to 0.015% of Ti,
0 to 0.010% of Bi, and
a balance comprising Fe and impurities,
a cold rolling process of cold-rolling the hot rolled steel sheet to obtain a cold rolled steel sheet;
a decarburization annealing process of decarburization-annealing the cold rolled steel sheet to obtain a decarburization annealed sheet;
an annealing separator applying process of applying and drying an annealing separator including MgO to the decarburization annealed sheet;
a final annealing process of final-annealing the decarburization annealed sheet after applying the annealing separator to obtain a final annealed sheet;
an annealing separator removing process of removing a redundant annealing separator from a surface of the final annealed sheet; and
an insulation coating forming process of forming an insulation coating on the surface of the final annealed sheet,
wherein, in the decarburization annealing process,
PH2O/PH2 which is an oxidation degree of an atmosphere is 0.01 to 0.15, an annealing temperature is 750 to 900° C., and a holding is 10 to 600 seconds,
wherein, in the annealing separator applying process,
the annealing separator further includes MCl which is at least one selected from chlorides of an alkali metal, an alkaline earth metal, and Bi, and MCl/MgO which is a mass ratio of MgO and MCl is 2 to 40%,
wherein, in the final annealing process,
an oxidation degree is 0.00010 to 0.2 when an atmosphere includes hydrogen, or a dew point is 0° C. or less when an atmosphere comprises an inert gas without hydrogen, and
wherein, in the insulation coating forming process,
an insulation coating forming solution in which a phosphoric acid and a metal compound are included and in which a mass ratio of the phosphoric acid to the metal compound is 2:1 to 1:2 is applied and is baked at 600 to 1150° C., and after decreasing a temperature, an insulation coating forming solution in which a phosphate and a colloidal silica are included and in which a metal compound is not included is applied and is baked at 600 to 1150° C., in order to form the insulation coating.