Grain-oriented electrical steel sheet and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-11031163-B2
Application number	US-201716068121-A
Country	US
Kind code	B2
Filing date	Jan 24, 2017
Priority date	Jan 25, 2016
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

An excellent low noise property and excellent low iron loss property are obtained. A grain-oriented electrical steel sheet includes refined magnetic domains formed by electron beam irradiation. When the maximum magnetic flux density is 1.7 T, the grain-oriented electrical steel sheet has a residual magnetic flux density of 0.1 to 0.7 times the residual magnetic flux density before the electron beam irradiation and a maximum magnetizing force of 1.1 to 2.0 times the maximum magnetizing force before the electron beam irradiation.

First claim

The invention claimed is:

1. A grain-oriented electrical steel sheet comprising refined magnetic domains,
wherein, in a condition excited by a magnetic field having a maximum magnetic flux density of 1.7 T, the grain-oriented electrical steel sheet has:
(i) a residual magnetic flux density that is 0.1 to 0.7 times the residual magnetic flux density measured after the grain-oriented electrical steel sheet is subjected to annealing in a nitrogen atmosphere at 800° C. for 3 hours, and
(ii) a maximum magnetizing force that is 1.1 to 2.0 times the maximum magnetizing force measured after the grain-oriented electrical steel sheet is subjected to annealing in a nitrogen atmosphere at 800° C. for 3 hours.

2. The grain-oriented electrical steel sheet comprising refined magnetic domains according to claim 1 , wherein the grain-oriented electrical steel sheet has a hysteresis loss at 50 Hz and 1.7 T of 0.28 W/kg or less.

3. The grain-oriented electrical steel sheet comprising refined magnetic domains according to claim 1 , wherein the grain-oriented electrical steel sheet has:
(i) a residual magnetic flux density that is 0.1 to 0.5 times the residual magnetic flux density measured after the grain-oriented electrical steel sheet is subjected to annealing in a nitrogen atmosphere at 800° C. for 3 hours, and
(ii) a maximum magnetizing force that is 1.1 to 1.5 times the maximum magnetizing force measured after the grain-oriented electrical steel sheet is subjected to annealing in a nitrogen atmosphere at 800° C. for 3 hours.

4. The grain-oriented electrical steel sheet comprising refined magnetic domains according to claim 2 , wherein the grain-oriented electrical steel sheet has:
(i) a residual magnetic flux density that is 0.1 to 0.5 times the residual magnetic flux density measured after the grain-oriented electrical steel sheet is subjected to annealing in a nitrogen atmosphere at 800° C. for 3 hours, and
(ii) a maximum magnetizing force that is 1.1 to 1.5 times the maximum magnetizing force measured after the grain-oriented electrical steel sheet is subjected to annealing in a nitrogen atmosphere at 800° C. for 3 hours.

5. A method for manufacturing the grain-oriented electrical steel sheet of claim 1 , the method comprising:
subjecting a steel slab to hot rolling to obtain a hot rolled steel sheet;
subjecting the hot rolled steel sheet to hot band annealing to obtain a hot rolled steel sheet after hot band annealing;
subjecting the hot rolled steel sheet after hot band annealing to cold rolling once or cold rolling twice or more with intermediate annealing in between to obtain a cold rolled steel sheet with a final sheet thickness;
subjecting the cold rolled steel sheet to decarburization annealing to obtain a cold rolled steel sheet after decarburization annealing;
applying an annealing separator including MgO to a surface of the cold rolled steel sheet after decarburization annealing and then subjecting the cold rolled steel sheet after decarburization annealing to final annealing to obtain a steel sheet after final annealing; and
subjecting the steel sheet after final annealing to magnetic domain refining treatment with electron beam irradiation;
wherein during the magnetic domain refining treatment, the electron beam irradiation is performed with a beam diameter of 220 μm or less in an orthogonal direction that is orthogonal to a scanning direction of the electron beam, and with a ratio of beam maximum intensity in the orthogonal direction with respect to beam maximum intensity in the scanning direction of 0.7 or more to 1.3 or less; and
wherein the electron beam irradiation is performed using two or more beam control coils, an accelerating voltage of 90 kV or more, and a stigmator,
thereby producing the grain-oriented electrical steel sheet of claim 1 .

Assignees

• Jfe Steel Corp

Inventors

• Omura Takeshi
• Takajo Shigehiro
• Inoue Hirotaka

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C21D8/1294 Primary

  involving a localised treatment · CPC title

• C21D8/0236

  Cold rolling · CPC title

• C21D8/0268

  between cold rolling steps · CPC title

• C21D8/0247

  characterised by the heat treatment · CPC title