Grain-oriented electrical steel sheet and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-2022098692-A1
Application number	US-202017421845-A
Country	US
Kind code	A1
Filing date	Jan 16, 2020
Priority date	Jan 16, 2019
Publication date	Mar 31, 2022
Grant date	—

Abstract

The grain-oriented electrical steel sheet is a grain-oriented electrical steel sheet which does not have an inorganic coating containing forsterite as a main component, including a base steel sheet having a predetermined chemical component, a silicon-containing oxide layer provided on the base steel sheet, an iron-based oxide layer provided on the silicon-containing oxide layer, and a tension-insulation coating provided on the iron-based oxide layer, having a thickness of 1 to 3 μm, and containing phosphate and colloidal silica as main components. When elemental analysis is performed from a surface of the tension-insulation coating in a sheet thickness direction by glow discharge optical emission spectrometry, predetermined requirements are satisfied.

First claim

1 . A grain-oriented electrical steel sheet which does not have an inorganic coating containing forsterite as a main component, comprising:
a base steel sheet; a silicon-containing oxide layer provided on the base steel sheet; an iron-based oxide layer provided on the silicon-containing oxide layer; and a tension-insulation coating provided on the iron-based oxide layer, having a thickness of 1 to 3 μm, and containing phosphate and colloidal silica as main components; wherein the base steel sheet contains, as chemical components, in terms of mass %, 2.5 to 4.5% of Si, 0.05 to 1.00% of Mn, 0% or more and less than 0.05% of Al, 0% or more and less than 0.1% of C, 0% or more and less than 0.05% of N, 0% or more and less than 0.1% of S, 0% or more and less than 0.05% of Se and 0% or more and less than 0.01% of Bi, and the remainder: Fe and impurities, wherein, when elemental analysis is performed from a surface of the tension-insulation coating in a sheet thickness direction by glow discharge optical emission spectrometry, (a) in a profile of a Si light emission intensity, there are four or more inflection points; (b) in the sheet thickness direction, the inflection point of the Si light emission intensity present closest to the base steel sheet side is present within a range of 0.3 to 1.5 μm toward the side of the surface of the tension-insulation coating from a saturation point at which an Fe light emission intensity is a maximum, and (c) a peak of the Si light emission intensity present closest to the base steel sheet side has a light emission intensity that is 1.3 times or more and 2.0 times or less the Si light emission intensity in the base steel sheet.

2 . The grain-oriented electrical steel sheet according to claim 1 ,
wherein the silicon-containing oxide layer contains silica and fayalite as main components, and wherein the tension-insulation coating contains 25 to 45 mass % of colloidal silica, with a remainder that contains one or more of aluminum phosphate, magnesium phosphate, zinc phosphate, manganese phosphate, cobalt phosphate, and iron phosphate as main components.

3 . The grain-oriented electrical steel sheet according to claim 1 ,
wherein the iron-based oxide layer contains magnetite, hematite and fayalite as main components.

4 . The grain-oriented electrical steel sheet according to claim 1 ,
wherein a thickness of the base steel sheet is 0.27 mm or less.

5 . A method for manufacturing a grain-oriented electrical steel sheet which includes a base steel sheet and a tension-insulation coating and does not have an inorganic coating containing forsterite as a main component, comprising:
a washing process of cleaning a surface of the grain-oriented electrical steel sheet; a surface treatment process of treating the surface of the grain-oriented electrical steel sheet which has been subjected to the washing process using a surface treatment liquid which contains one or more of sulfuric acid, phosphoric acid and nitric acid and having a total acid concentration of 2 to 20% and a liquid temperature of 70 to 90° C.; a heating treatment process of heating the grain-oriented electrical steel sheet which has been subjected to the surface treatment process at a temperature of 700 to 900° C. for 10 to 60 seconds in an atmosphere having an oxygen concentration of 1 to 21 volume % and a dew point of −20 to 30° C.; and a tension-insulation coating forming process of forming a tension-insulation coating which has a thickness of 1 to 3 μm by applying a treatment solution for forming a tension-insulation coating containing phosphate and colloidal silica as main components to the surface of the grain-oriented electrical steel sheet after the heating treatment process, and heating is performed at an average heating rate of 20 to 100° C./s within 1.0 to 20 seconds after the application, and baking is performed at a temperature of 850 to 950° C. for 10 to 60 seconds.

6 . The method for manufacturing a grain-oriented electrical steel sheet according to claim 5 , further comprising:
before the washing process, a hot rolling process of subjecting a steel piece which contains, as chemical components, in terms of mass %, 2.5 to 4.5% of Si, 0.05 to 1.00% of Mn, less than 0.05% of Al, less than 0.1% of C, less than 0.05% of N, less than 0.1% of S, less than 0.05% of Se and less than 0.01% of Bi with the remainder comprising Fe and impurities to hot rolling; an optional annealing process; a cold rolling process of performing one cold rolling or two or more cold rollings having intermediate annealing performed between the cold rollings; a decarburization annealing process; and a final annealing process of applying an annealing separator obtained by incorporating bismuth chloride into a mixture of MgO and Al 2 O 3 or an annealing separator obtained by incorporating a bismuth compound and a metallic chloride compound into a mixture of MgO and Al 2 O 3 , drying the annealing separator, and then performing final annealing.

7 . The grain-oriented electrical steel sheet according to claim 2 ,
wherein the iron-based oxide layer contains magnetite, hematite and fayalite as main components.

8 . The grain-oriented electrical steel sheet according to claim 2 ,
wherein a thickness of the base steel sheet is 0.27 mm or less.

9 . The grain-oriented electrical steel sheet according to claim 3 ,
wherein a thickness of the base steel sheet is 0.27 mm or less.

Assignees

• Nippon Steel Corp

Inventors

• Takeda Kazutoshi
• Tanaka Ichiro
• Suenaga Tomoya
• Kataoka Takashi
• KUNITA Yuki

Classifications

• C23G1/085

  solutions containing HNO3 · CPC title

• C22C38/60

  containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur · CPC title

• C22C38/02

  containing silicon · CPC title

• C22C38/04

  containing manganese · CPC title

• C21D9/46 Primary

  for sheet metals · CPC title