Grain-oriented electrical steel sheet and decarburized steel sheet used for manufacturing the same

Patent metadata

Field	Value
Publication number	US-2018305784-A1
Application number	US-201615768696-A
Country	US
Kind code	A1
Filing date	Oct 26, 2016
Priority date	Oct 26, 2015
Publication date	Oct 25, 2018
Grant date	—

Abstract

A grain-oriented electrical steel sheet includes: a chemical composition represented by, in mass %, Si: 1.8% to 7.0%, Cu: 0.03% to 0.60%, and the balance: Fe and impurities; and a primary coating film containing forsterite on a surface of the steel sheet, in which a Cu/Fe light-emitting intensity ratio at an interface region between the primary coating film and the surface of the steel sheet is 0.30 or less.

First claim

1 . A grain-oriented electrical steel sheet, comprising:
a chemical composition represented by in mass %, Si: 1.8% to 7.0%, Cu: 0.03% to 0.60%, and the balance: Fe and impurities; and a primary coating film containing forsterite on a surface of the steel sheet, wherein a Cu/Fe light-emitting intensity ratio at an interface region between the primary coating film and the surface of the steel sheet is 0.30 or less.

2 . A decarburized steel sheet for a grain-oriented electrical steel sheet, comprising:
a chemical composition represented by, in mass %, C: 0.03% to 0.15%, Si: 1.8% to 7.0%, Mn: 0.02% to 0.30%, S: 0.005% to 0.040%, acid-soluble Al: 0.010% to 0.065%, N: 0.0030% to 0.0150%, Cu: 0.03% to 0.60%, Sn: 0% to 0.5%, Ge, Se, Sb, Te, Pb, or Bi, or an arbitrary combination of these: 0.0005% to 0.030% in total, and the balance: Fe and impurities; and an oxide film on a surface of the steel sheet, wherein a Cu/Fe light-emitting intensity ratio at an interface region between the oxide film and the surface of the steel sheet is 0.60 or less.

3 . A manufacturing method of a grain-oriented electrical steel sheet, comprising:
a step of heating a slab in a temperature zone of 1300° C. to 1490° C.; a step of obtaining a hot-rolled steel sheet by performing hot rolling of the slab; a step of coiling the hot-rolled steel sheet in a temperature zone of 600° C. or less; a step of performing hot-rolled sheet annealing of the hot-rolled steel sheet; after the hot-rolled sheet annealing, a step of performing cold rolling and obtaining a cold-rolled steel sheet; a step of performing decarburization annealing of the cold-rolled steel sheet; and after the decarburization annealing, a step of applying an annealing separating agent containing MgO and performing finish annealing, wherein the step of performing the hot rolling includes a step of performing rough rolling with a finishing temperature set to 1200° C. or less and a step of performing finish rolling with a start temperature set to 1000° C. or more and a finishing temperature set to 950° C. to 1100° C., in the hot rolling, the finish rolling is started within 300 seconds after start of the rough rolling, cooling at a cooling rate of 50° C./second or more is started within 10 seconds after finish of the finish rolling, pickling with a holding temperature set to 50° C. or more and a holding time period set to 30 seconds or more is performed in a pickling bath containing a nitric acid, a pickling inhibitor, and a surface active agent after the hot rolling and before finish of the cold rolling, and the slab includes a chemical composition represented by, in mass %, C: 0.03% to 0.15%, Si: 1.8% to 7.0%, Mn: 0.02% to 0.30%, S: 0.005% to 0.040%, acid-soluble Al: 0.010% to 0.065%, N: 0.0030% to 0.0150%, Cu: 0.03% to 0.60%, Sn: 0% to 0.5%, Ge, Se, Sb, Te, Pb, or Bi, or an arbitrary combination of these: 0.0005% to 0.030% in total, and the balance: Fe and impurities.

4 . The manufacturing method of the grain-oriented electrical steel sheet according to claim 3 , wherein
the pickling bath further contains a nitrate.

5 . A manufacturing method of a decarburized steel sheet for a grain-oriented electrical steel sheet, comprising:
a step of heating a slab in a temperature zone of 1300° C. to 1490° C.; a step of obtaining a hot-rolled steel sheet by performing hot rolling of the slab; a step of coiling the hot-rolled steel sheet in a temperature zone of 600° C. or less; a step of performing hot-rolled sheet annealing of the hot-rolled steel sheet; after the hot-rolled sheet annealing, a step of performing cold rolling and obtaining a cold-rolled steel sheet; and a step of performing decarburization annealing of the cold-rolled steel sheet; wherein the step of performing the hot rolling includes a step of performing rough rolling with a finishing temperature set to 1200° C. or less and a step of performing finish rolling with a start temperature set to 1000° C. or more and a finishing temperature set to 950° C. to 1100° C., in the hot rolling, the finish rolling is started within 300 seconds after start of the rough rolling, cooling at a cooling rate of 50° C./second or more is started within 10 seconds after finish of the finish rolling, pickling with a holding temperature set to 50° C. or more and a holding time period set to 30 seconds or more is performed in a pickling bath containing a nitric acid, a pickling inhibitor, and a surface active agent after the hot rolling and before finish of the cold rolling, and the slab includes a chemical composition represented by, in mass % C: 0.03% to 0.15%, Si: 1.8% to 7.0%, Mn: 0.02% to 0.30%, S: 0.005% to 0.040%, acid-soluble Al: 0.010% to 0.065%, N: 0.0030% to 0.0150%, Cu: 0.03% to 0.60%, Sn: 0% to 0.5%, Ge, Se, Sb, Te, Pb, or Bi, or an arbitrary combination of these: 0.0005% to 0.030% in total, and the balance: Fe and impurities.

6 . The manufacturing method of the decarburized steel sheet for a grain-oriented electrical steel sheet according to claim 5 , wherein
the pickling bath further contains a nitrate.

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Fujimura Hiroshi
• Takahashi Fumiaki
• Kataoka Takashi

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

• C21D8/12

  during manufacturing of articles with special electromagnetic properties · CPC title

• C21D8/1261

  following hot rolling · CPC title

• C22C38/04

  containing manganese · CPC title

• C22C38/008

  containing tin · CPC title