# US 12,180,558 B2 · Method for manufacturing grain-oriented electrical steel sheet

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- Number: US 12,180,558 B2
- Document ID: US12180558B2
- Status: Granted
- Kind: B2
- Application number: 17/422,695
- Filed: 2020-01-16
- Published: 2022-03-31
- Granted: 2024-12-31
- Earliest claimed: 2019-01-16
- Assignees: Nippon Steel Corporation
- Applicants: Nippon Steel Corporation
- Inventors: Yoshiyuki Ushigami; Shuichi Nakamura; Hiroyasu Fujii; Norikazu Fujii
- Web page: https://patentgrep.com/patent/US12180558B2

## CPC

- C21D 9/46: for sheet metals
- C21D 1/76: Adjusting the composition of the atmosphere
- C21D 3/04: Decarburising
- 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 8/1261: {following hot rolling}
- C21D 8/1266: {between cold rolling steps}
- C21D 8/1272: {Final recrystallisation annealing}
- C21D 8/1283: {Application of a separating or insulating coating}
- 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 38/20: with copper
- C22C 38/32: with boron
- C22C 38/34: with more than 1.5% by weight of silicon
- C22C 38/40: with nickel
- 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 8/02: Pretreatment of the material to be coated (C23C8/04 takes precedence)
- C23C 8/10: Oxidising
- C23C 8/26: of ferrous surfaces
- C23C 8/80: After-treatment
- C23C 24/04: Impact or kinetic deposition of particles
- C23C 24/08: by application of heat or pressure and heat (C23C24/04 takes precedence)
- C23C 26/00: Coating not provided for in groups C23C2/00 - C23C24/00
- H01F 1/18: with insulating coating
- C21D 2201/05: Grain orientation
- 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)
- 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 manufacturing a grain-oriented electrical steel sheet includes: a silicon steel material production process of producing a silicon steel material; a hot rolling process of obtaining a hot rolled sheet by subjecting the silicon steel material to hot rolling; a cold rolling process of obtaining a steel sheet of a final sheet thickness by subjecting the hot rolled sheet to a single cold rolling process or multiple cold rolling processes having intermediate annealing performed between the cold rolling processes; a decarburization annealing process of subjecting the steel sheet to decarburization annealing; and a final annealing process of applying an annealing separator containing alumina as a main component to the steel sheet and subjecting the steel sheet to final annealing.

## Claims

### Claim 1

A method for manufacturing a grain-oriented electrical steel sheet, comprising:
a silicon steel material production process of producing a silicon steel material;
a hot rolling process of obtaining a hot rolled sheet by subjecting the silicon steel material to hot rolling;
a cold rolling process of obtaining a steel sheet of a final sheet thickness by subjecting the hot rolled sheet to a single cold rolling process or multiple cold rolling processes having intermediate annealing performed between the cold rolling processes;
a decarburization annealing process of subjecting the steel sheet to decarburization annealing; and
a final annealing process of applying an annealing separator containing alumina as a main component to the steel sheet and subjecting the steel sheet to final annealing,
wherein the silicon steel material contains: in terms of mass %,
Si: 0.8 to 7.0%;
C: 0.085% or less;
acid-soluble Al: 0.010 to 0.065%;
N: 0.004 to 0.012%;
Mn: 1.00% or less;
S: 0.050% or less;
a total of 0.01 to 0.20% of one or both of Sn and Sb; and
the remainder: Fe and impurities,
wherein the decarburization annealing process includes: performing the decarburization annealing using a decarburization annealing furnace including a heating area and a soaking area,
an oxidation degree P1 of an atmosphere gas in the heating area satisfies the following Expression 1, and
an oxidation degree P2 of an atmosphere gas in the soaking area satisfies the following Expression 2, and
wherein the P1 and the P2 described above satisfy the following Expression 3:
0.01≤P1≤0.15 (Expression 1);
0.01≤P2≤0.15 (Expression 2); and
P1>P2 (Expression 3).

### Claim 2 (depends on 1)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 1, wherein the silicon steel material further contains, in terms of mass %, Cr: 0.02 to 0.50%.

### Claim 3 (depends on 1)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 1, wherein the silicon steel material further contains, in terms of mass %,
Cu: 0% or more and 0.4% or less;
P: 0% or more and 0.5% or less;
Ni: 0% or more and 1.0% or less;
B: 0% or more and 0.008% or less;
V: 0% or more and 0.15% or less;
Nb: 0% or more and 0.20% or less;
Mo: 0% or more and 0.10% or less;
Ti: 0% or more and 0.015% or less; and
Bi: 0% or more and 0.010% or less.

### Claim 4 (depends on 1)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 1, further comprising:
a nitriding treatment process from before the decarburization annealing process to before secondary recrystallization initiation in the final annealing process.

### Claim 5 (depends on 1)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 1, further comprising:
a hot-band annealing process of subjecting the hot rolled sheet obtained in the hot rolling process to annealing after the hot rolling process and before the cold rolling process.

### Claim 6 (depends on 2)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 2, wherein the silicon steel material further contains, in terms of mass %,
Cu: 0% or more and 0.4% or less;
P: 0% or more and 0.5% or less;
Ni: 0% or more and 1.0% or less;
B: 0% or more and 0.008% or less;
V: 0% or more and 0.15% or less;
Nb: 0% or more and 0.20% or less;
Mo: 0% or more and 0.10% or less;
Ti: 0% or more and 0.015% or less; and
Bi: 0% or more and 0.010% or less.

### Claim 7 (depends on 2)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 2, further comprising:
a nitriding treatment process from before the decarburization annealing process to before secondary recrystallization initiation in the final annealing process.

### Claim 8 (depends on 3)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 3, further comprising:
a nitriding treatment process from before the decarburization annealing process to before secondary recrystallization initiation in the final annealing process.

### Claim 9 (depends on 2)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 2, further comprising:
a hot-band annealing process of subjecting the hot rolled sheet obtained in the hot rolling process to annealing after the hot rolling process and before the cold rolling process.

### Claim 10 (depends on 3)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 3, further comprising:
a hot-band annealing process of subjecting the hot rolled sheet obtained in the hot rolling process to annealing after the hot rolling process and before the cold rolling process.

### Claim 11 (depends on 1)

The method for manufacturing a grain-oriented electrical steel sheet according to claim 1, wherein the silicon steel material contains, in terms of mass %, S: 0.020% to 0.050%.