Grain-oriented electrical steel sheet and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-11566302-B2
Application number	US-201716468087-A
Country	US
Kind code	B2
Filing date	Dec 14, 2017
Priority date	Dec 14, 2016
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

Provided is a grain-oriented electrical steel sheet having better transformer iron loss property than conventional grain-oriented electrical steel sheets. A grain-oriented electrical steel sheet comprises: a steel substrate; a forsterite film on a surface of the steel substrate; and a Cr-depleted layer at a boundary between the steel substrate and the forsterite film, the Cr-depleted layer having a Cr concentration that is 0.70 times to 0.90 times a Cr concentration of the steel substrate.

First claim

The invention claimed is:

1. A grain-oriented electrical steel sheet comprising:
a steel substrate;
a forsterite film on a surface of the steel substrate; and
a Cr-depleted layer at a boundary between the steel substrate and the forsterite film, the Cr-depleted layer having a Cr concentration that is 0.70 times to 0.90 times a Cr concentration of the steel substrate,
wherein the steel substrate contains Cr: 0.01 mass % or more and 0.25 mass % or less.

2. The grain-oriented electrical steel sheet according to claim 1 , wherein the steel substrate contains Cr: 0.02 mass % or more and 0.20 mass % or less.

3. The grain-oriented electrical steel sheet according to claim 1 , wherein the steel substrate contains Cr: 0.15 mass % or more and 0.25 mass % or less.

4. The grain-oriented electrical steel sheet according to claim 1 , wherein the steel substrate contains C: 0.08 mass % or less.

5. The grain-oriented electrical steel sheet according to claim 1 , wherein the steel substrate contains Si: 2.0 mass % to 8.0 mass %.

6. The grain-oriented electrical steel sheet according to claim 1 , wherein the steel substrate contains Mn: 0.005 mass % to 1.000 mass %.

7. A method for manufacturing the grain-oriented electrical steel sheet of claim 1 , the method comprising:
subjecting a grain-oriented electrical steel slab to hot rolling, to obtain a hot-rolled steel sheet;
subjecting the hot-rolled steel sheet to cold rolling either once, or twice or more with intermediate annealing performed therebetween, to obtain a cold-rolled steel sheet having a final sheet thickness;
subjecting the cold-rolled steel sheet to decarburization annealing to obtain a decarburization-annealed steel sheet;
applying an annealing separator composed mainly of MgO to the decarburization-annealed steel sheet;
thereafter subjecting the decarburization-annealed steel sheet in coil form to final annealing to obtain a final-annealed steel sheet comprising a steel substrate and a forsterite film on a surface of the steel substrate; and
thereafter forming a tension coating on the final-annealed steel sheet,
wherein oxidizability of atmosphere in at least a temperature range of 300° C. to 600° C. in a sheet passing process from after the final annealing to when baking the tension coating is controlled to form, at a boundary between the steel substrate and the forsterite film, a Cr-depleted layer having a Cr concentration that is 0.70 times to 0.90 times a Cr concentration of the steel substrate,
wherein the grain-oriented electrical steel slab contains Cr: 0.01 mass % or more and 0.25 mass % or less.

8. The method for manufacturing a grain-oriented electrical steel sheet according to claim 7 , wherein after the final annealing and before forming the Cr-depleted layer, the final-annealed steel sheet is passed through a pass line including at least one part that imparts bending in a direction opposite to coil set remaining in the final-annealed steel sheet, and the oxidizability of atmosphere when forming the Cr-depleted layer is controlled to an oxygen partial pressure P O2 of 0.01 atm to 0.25 atm.

9. The method for manufacturing a grain-oriented electrical steel sheet according to claim 7 , wherein the grain-oriented electrical steel slab contains Cr: 0.02 mass % or more and 0.20 mass % or less.

10. The method for manufacturing a grain-oriented electrical steel sheet according to claim 7 , wherein the grain-oriented electrical steel slab contains Cr: 0.15 mass % or more and 0.25 mass % or less.

11. The method for manufacturing a grain-oriented electrical steel sheet according to claim 8 , wherein a curvature radius of the bending is 750 mm or less.

12. The method for manufacturing a grain-oriented electrical steel sheet according to claim 8 , wherein the grain-oriented electrical steel slab contains Cr: 0.02 mass % or more and 0.20 mass % or less.

13. The method for manufacturing a grain-oriented electrical steel sheet according to claim 11 , wherein the grain-oriented electrical steel slab contains Cr: 0.02 mass % or more and 0.20 mass % or less.

Assignees

• Jfe Steel Corp

Inventors

• Omura Takeshi
• Inoue Hirotaka
• Senda Kunihiro
• Okabe Seiji

Classifications

• C21D8/1288

  Application of a tension-inducing coating · CPC title

• C22C38/04

  containing manganese · CPC title

• C22C38/008

  containing tin · CPC title

• H01F1/14791

  Fe-Si-Al based alloys, e.g. Sendust · CPC title

• C22C38/60

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