Grain-oriented electrical steel sheet, intermediate steel sheet for grain-oriented electrical steel sheet, and methods for manufacturing same

Patent metadata

Field	Value
Publication number	US-12331377-B2
Application number	US-202017421758-A
Country	US
Kind code	B2
Filing date	Jan 16, 2020
Priority date	Jan 16, 2019
Publication date	Jun 17, 2025
Grant date	Jun 17, 2025

Abstract

This grain-oriented electrical steel sheet includes a base steel sheet, an intermediate layer that is formed on a surface of the base steel sheet and mainly contains silicon oxide, and an insulation coating that is formed on the surface of the intermediate layer. A number density of the oxide particles in a region from the surface of the base steel sheet to a depth of 10 μm toward an inside of the base steel sheet is 0.020 oxide particles/μm 2 or less. In the grain-oriented electrical steel sheet, an area rate of an intermediate layer-remaining region n which the intermediate layer does not peel off but remains in a region in which the insulation coating peels off after a bend test performed using a mandrel according to JIS K 5600-5-1 (1999) is 20% or more.

First claim

The invention claimed is:

1. A grain-oriented electrical steel sheet comprising:
a base steel sheet;
an intermediate layer that is formed on a surface of the base steel sheet and mainly contains silicon oxide; and
an insulation coating that is formed on a surface of the intermediate layer,
wherein a number density of oxide particles in a region from the surface of the base steel sheet to a depth of 10 μm toward an inside of the base steel sheet is 0.020 oxide particles/μm 2 or less,
an area rate of an intermediate layer-remaining region in which the intermediate layer does not peel off but remains in a region in which the insulation coating peels off after a bend test performed using a mandrel with a diameter of 10 to 16 mm according to JIS K 5600 May 1 (1999) is 20% or more, and
in a case where the evaluation area of insulation peeling defined by the following expression is less than 5%, the area rate of the intermediate layer-remaining region is re-evaluated by using a mandrel having a smaller diameter and is 20% or more,
(Evaluation area of insulation coating peeling)=(diameter of mandrel)×(ratio of circumference to diameter)÷2.

2. The grain-oriented electrical steel sheet according to claim 1 , wherein a composition of the intermediate layer comprises a Fe content of less than 30% by atom, a P content of less than 5% by atom, a Si content of less than 50% by atom and 20% by atom or more, an O content of less than 80% by atom and 50% by atom or more, and a Mg content of 10% by atom or less.

3. A method for manufacturing the grain-oriented electrical steel sheet according to claim 1 comprising:
a hot rolling process of heating a slab at 1280° C. or lower and then performing hot rolling to manufacture a hot-rolled steel sheet;
a hot-band annealing process of performing hot band annealing on the hot-rolled steel sheet to manufacture an annealed steel sheet;
a cold rolling process of performing cold rolling on the annealed steel sheet to manufacture a cold-rolled steel sheet;
a decarburization annealing process of performing decarburization annealing on the cold-rolled steel sheet to manufacture a base steel sheet;
an annealing separator applying process of applying an annealing separator having a composition containing 50 mass % or more of alumina and, as a remainder, 0 to 50 mass % of magnesia to the base steel sheet;
a final annealing process of performing final annealing on the base steel sheet after the annealing separator applying process;
a cooling process of cooling the base steel sheet after the final annealing process in an atmosphere having an oxidation degree P H2O /P H2 , which is a ratio of a water vapor partial pressure to a hydrogen partial pressure, within a temperature range of 1100° C. to 500° C. set to 0.30 to 100000;
an intermediate layer forming process of performing a heat treatment on the base steel sheet after the cooling process to form an intermediate layer mainly containing silicon oxide on a surface of the base steel sheet; and
an insulation coating forming process of forming an insulation coating on a surface of the intermediate layer after the intermediate layer forming process.

Assignees

• Nippon Steel Corp

Inventors

• Yamamoto Shinji
• Ushigami Yoshiyuki
• TAKATANI Shinsuke

Classifications

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• H01F41/0233

  Manufacturing of magnetic circuits made from sheets (magnetic cores made from sheets H01F27/245; soft magnetic alloys in the form of sheets H01F1/16) · CPC title

• H01F1/18

  with insulating coating · CPC title

• C22C38/06

  containing aluminium · CPC title

• C22C38/04

  containing manganese · CPC title