Grain-oriented electrical steel sheet and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-12065712-B2
Application number	US-202017422244-A
Country	US
Kind code	B2
Filing date	Jan 16, 2020
Priority date	Jan 16, 2019
Publication date	Aug 20, 2024
Grant date	Aug 20, 2024

Abstract

This grain-oriented electrical steel sheet has a base steel sheet in which a final-annealed film is substantially not present on a surface, an intermediate layer that is disposed on a surface of the base steel sheet and mainly contains silicon oxide, and an insulation coating disposed on a surface of the intermediate layer. In the intermediate layer, a value obtained by dividing a standard deviation σ of a thickness of the intermediate layer by an average value T of the thickness of the intermediate layer is 0.500 or less.

First claim

The invention claimed is:

1. A grain-oriented electrical steel sheet comprising:
a base steel sheet in which a final-annealed film is substantially not present on a surface;
an intermediate layer that is disposed on a surface of the base steel sheet and mainly contains silicon oxide; and
an insulation coating disposed on a surface of the intermediate layer,
wherein, in the intermediate layer, a value obtained by dividing a standard deviation σ of a thickness of the intermediate layer by an average value T of the thickness of the intermediate layer is 0.500 or less.

2. A method for manufacturing the grain-oriented electrical steel sheet according to claim 1 , the method comprising:
heating a slab containing Si and then performing hot rolling to obtain a hot-rolled steel sheet,
performing hot band annealing on the hot-rolled steel sheet to obtain an annealed steel sheet,
performing cold rolling on the annealed steel sheet once or twice or more with intermediate annealing performed therebetween to obtain a cold-rolled steel sheet,
performing decarburization annealing on the cold-rolled steel sheet to obtain a decarburization-annealed steel sheet,
heating the decarburization-annealed steel sheet with an annealing separator having a MgO content of 10 mass % to 50 mass % applied to a surface of the decarburization-annealed steel sheet and then removing the annealing separator to obtain a final-annealed steel sheet,
performing thermal oxidation annealing on the final-annealed steel sheet to form an intermediate layer on a surface of the final-annealed steel sheet, and
forming an insulation coating on the final-annealed steel sheet having the intermediate layer formed thereon,
wherein, during cooling for final annealing,
T1 is set to 1100° C. in a case where a final annealing temperature is 1100° C. or higher and T1 is set to the final annealing temperature in a case where the final annealing temperature is lower than 1100° C., and
the decarburization-annealed steel sheet is cooled within a temperature range of T1 to 500° C. in an atmosphere having an oxidation degree (P H2O /P H2 ) of 0.3 to 100000,
in the thermal oxidation annealing for the formation of the intermediate layer,
during heating,
an average heating rate within a temperature range of 300° C. to 750° C. is set to 20° C./second to 200° C./second, an oxidation degree (P H2O /P H2 ) within the temperature range is set to 0.0005 to 0.1, the final-annealed steel sheet is heated up to a temperature range of 750° C. to 1150° C. and
held within the temperature range of 750° C. to 1150° C.
in an atmosphere having an oxidation degree (P H2O /P H2 ) of 0.0005 to 0.2 for 10 seconds to 90 seconds.

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

• H01F1/147

  Alloys characterised by their composition {(treatment thereof for enhancing their electromagnetic properties C21D8/12)} · CPC title

• C22C2202/02

  Magnetic · CPC title

• C22C38/16

  containing copper · CPC title

• C22C38/06

  containing aluminium · CPC title