Grain-oriented electrical steel sheet and method of manufacturing grain-oriented electrical steel sheet

Patent metadata

Field	Value
Publication number	US-11060159-B2
Application number	US-201816628951-A
Country	US
Kind code	B2
Filing date	Jul 13, 2018
Priority date	Jul 13, 2017
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

A grain-oriented electrical steel sheet according to an aspect of the present invention includes: a steel sheet 1; an intermediate layer 4 containing Si and O, arranged on the steel sheet; and an insulation coating 3 arranged on the intermediate layer 4, in which the intermediate layer 4 contains a metal phosphide 5, a thickness of the intermediate layer 4 is 4 nm or more, and an abundance of the metal phosphide 5 present is 1% to 30% by cross-sectional area fraction in a cross section of the intermediate layer 4.

First claim

The invention claimed is:

1. A grain-oriented electrical steel sheet comprising:
a steel sheet;
an intermediate layer containing Si and O, arranged on the steel sheet; and
an insulation coating arranged on the intermediate layer,
wherein the intermediate layer contains a metal phosphide,
a thickness of the intermediate layer is 4 nm or more, and
an abundance of the metal phosphide included is 1% to 30% by cross-sectional area fraction in a cross section of the intermediate layer.

2. The grain-oriented electrical steel sheet according to claim 1 ,
wherein the metal phosphide is a Fe phosphide which is one or more selected from the group consisting of Fe 3 P, Fe 2 P, and FeP.

3. The grain-oriented electrical steel sheet according to claim 1 ,
wherein the intermediate layer contains an α-Fe and/or an iron silicate in addition to the metal phosphide.

4. The grain-oriented electrical steel sheet according to claim 3 ,
wherein a total abundance of the metal phosphide, and the α-Fe and/or the iron silicate included is 1% to 30% by cross-sectional area fraction in the cross section of the intermediate layer.

5. The grain-oriented electrical steel sheet according to claim 1 ,
wherein the thickness of the intermediate layer is less than 400 nm.

6. The grain-oriented electrical steel sheet according to claim 1 ,
wherein a thickness of the insulation coating is 0.1 μm to 10 μm.

7. The grain-oriented electrical steel sheet according to claim 1 ,
wherein a surface roughness of the steel sheet is 0.5 μm or less by arithmetic average roughness Ra.

8. A method of manufacturing the grain-oriented electrical steel sheet according to claim 1 , the method comprising:
hot rolling a steel piece to obtain a hot-rolled steel sheet;
cold rolling the hot-rolled steel sheet to obtain a cold-rolled steel sheet;
decarburization annealing the cold-rolled steel sheet to form an oxide layer on a surface of the cold-rolled steel sheet;
applying an annealing separator onto the surface of the cold-rolled steel sheet having the oxide layer;
drying the annealing separator and winding the cold-rolled steel sheet;
final annealing the wound cold-rolled steel sheet;
applying a first solution;
further annealing the cold-rolled steel sheet to which the first solution is applied to form an intermediate layer containing a metal phosphide;
applying a second solution on a surface of the intermediate layer; and
baking the cold-rolled steel sheet to which the second solution is applied,
wherein the first solution contains phosphoric acid and a metal compound, and a mass ratio between the phosphoric acid and the metal compound is 2:1 to 1:2, in the annealing for forming the intermediate layer, an annealing temperature is 600° C. to 1150° C., an annealing time is 10 to 600 seconds, a dew point in an annealing atmosphere is −20° C. to 2° C., and a ratio between an amount of hydrogen and an amount of nitrogen in the annealing atmosphere is 75%:25%, and
an application amount of the first solution is controlled such that an abundance of the metal phosphide included is 1% to 30% by cross-sectional area fraction in a cross section of the intermediate layer thereby producing the grain-oriented electrical steel sheet of claim 1 .

9. The method of manufacturing the grain-oriented electrical steel sheet according to claim 8 , further comprising:
removing an inorganic mineral material film generated by the final annealing before the applying of the first solution,
wherein the annealing separator contains magnesia as a main component.

10. The method of manufacturing the grain-oriented electrical steel sheet according to claim 8 , further comprising:
annealing the hot-rolled steel sheet before the cold rolling.

Assignees

• Nippon Steel Corp

Inventors

• Takebayashi Seiki
• Nakamura Shuichi
• Fujii Hiroyasu
• Ushigami Yoshiyuki

Classifications

• C22C38/06

  containing aluminium · CPC title

• C22C38/04

  containing manganese · CPC title

• C22C38/02

  containing silicon · CPC title

• C22C38/001

  containing N · CPC title

• C22C38/00

  Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00) · CPC title