Grain-oriented electrical steel sheet, annealing separator, and method for manufacturing grain-oriented electrical steel sheet

Patent metadata

Field	Value
Publication number	US-11634787-B2
Application number	US-202017421215-A
Country	US
Kind code	B2
Filing date	Jan 8, 2020
Priority date	Jan 8, 2019
Publication date	Apr 25, 2023
Grant date	Apr 25, 2023

Abstract

Grain-oriented electrical steel sheet excellent in magnetic properties and excellent in adhesion of a primary coating to a base steel sheet, an annealing separator utilized for manufacture of grain-oriented electrical steel sheet, and a method for manufacturing grain-oriented electrical steel sheet are proposed. The grain-oriented electrical steel sheet is provided with a base metal steel sheet containing comprising a predetermined chemical composition and a primary coating formed on a surface of the base steel sheet and comprising Mg2SiO4 as a main constituent. The primary coating satisfies the conditions of (1) the number density D3 of the Al concentrated region: 0.020 to 0.180/μm2, (2) (total area S5 of regions which is anchoring oxide layer regions and is also Al concentrated regions)/(total area S3 of Al concentrated regions)≥33%, (3) distance H5 of mean value of length in thickness direction of regions which is anchoring oxide layer regions and is also Al concentrated regions minus H0: 0.4 to 4.0 μm, (4) (total area S1 of anchoring oxide layer regions)/(observed area S0)≥15%.

First claim

The invention claimed is:

1. A grain-oriented electrical steel sheet comprising
a base steel sheet having a chemical composition comprising, by mass %,
C: 0.0050% or less,
Si: 2.5 to 4.5%,
Mn: 0.02 to 0.20%,
one or more elements selected from the group comprised of S and Se: total of 0.005% or less,
sol. Al: 0.004% or less, and
N: 0.010% or less and

having a balance comprised of Fe and impurities and
a primary coating formed on a surface of the base steel sheet and comprising 50 to 95% by mass of Mg 2 SiO 4 as a constituent, where,
in a correlation distribution chart, which represents a correlation of a characteristic X-ray intensity and a surface height of the primary coating from a surface of the primary coating opposite to the base steel sheet obtained by projecting the surface height of the primary coating and constituent information in the primary coating on a plane having an area of 20 μm×15 μm parallel to a base steel sheet side, wherein a direction from a primary coating side toward the base steel sheet in a thickness direction of the base steel sheet is defined as positive,
when designating a center value of the surface height of the primary coating as H0, designating the primary coating existing at the height of H0+0.2 μm or more on the base steel sheet side as an “anchoring oxide layer region”, and designating the primary coating existing at the height of less than H0+0.2 μm on the primary coating side as a “surface oxide layer region”,
identifying a maximum value of the characteristic X-ray intensity of Al, and designating a region in which a characteristic X-ray intensity of Al is 20% or more of the maximum value of the Al as an “Al concentrated region”,
the primary coating satisfies the conditions of
(1) number density D3 of Al concentrated regions: 0.020 to 0.180/μm 2 ,
(2) (total area S5 of Al concentrated regions in anchoring oxide layer regions)/(total area S3 of Al concentrated regions)≥33%,
(3) distance H5 subtracting H0 from mean value of height of regions which is anchoring oxide layer regions and is also Al concentrated regions in thickness direction: 0.4 to 4.0 μm, and
(4) (total area S1 of anchoring oxide layer regions)/(observed area S0)≥15%.

2. The grain-oriented electrical steel sheet according to claim 1 , wherein
the primary coating comprises one or more elements selected from a group comprising Y, La, and Ce and one or more elements selected from a group comprising Ca, Sr, and Ba and,
in the correlation distribution chart of a characteristic X-ray intensity and a surface height of the primary coating, when identifying the maximum values of the characteristic X-ray intensities of Ca, Sr, and Ba and designating a region in which a characteristic X-ray intensity of Ca of 20% or more of the maximum value of the Ca is obtained, a region in which a characteristic X-ray intensity of Sr of 20% or more of the maximum value of the Sr is obtained, and a region in which a characteristic X-ray intensity of Ba of 20% or more of the maximum value of the Ba is obtained together as a “Ca group element concentrated region”,
the primary coating satisfies the conditions of
(5) a ratio of a total content of one or more elements selected from a group comprising Y, La, and Ce to the content of Mg 2 SiO 4 in the primary coating: 0.1 to 6.0 mass %,
(6) a ratio of a total content of one or more elements selected from a group comprising Ca, Sr, and Ba to the content of Mg 2 SiO 4 in the primary coating: 0.1 to 6.0 mass %, and
(7) a number density D4 of the Ca group element concentrated regions: 0.008/μm 2 or more.

3. An annealing separator used for manufacture of the grain-oriented electrical steel sheet according to claim 1 , having MgO as a main constituent,
which the annealing separator comprising one or more elements selected from a group comprising Y, La, and Ce and one or more elements selected from a group comprising Ca, Sr, and Ba,
when expressing ratios of contents of Mg, Y, La, Ce, Ca, Sr, and Ba to the content of MgO (mass %) as respectively [Mg], [Y], [La], [Ce], [Ca], [Sr], and [Ba],
satisfying
(8) (0.253[Y]+0.180[La]+0.170[Ce])/0.454[Mg]: 0.40 to 3.60 and
(9) (0.353[Ca]+0.252[Sr]+0.195[Ba])/0.454[Mg]: 0.20 to 2.20, and
furthermore, satisfying the conditions of
(10) mean particle size R1 of MgO: 0.08 to 1.50 μm,
(11) mean particle size R2 of particles comprising one or more elements selected from a group comprising Ca, Sr, and Ba in the Ca group element concentrated regions: 0.08 to 1.50 μm,
(12) (mean particle size R2)/(mean particle size R1): 0.3 to 3.0, and
(13) number density of particles comprising Ca group elements≥25,000,000,000/cm 3 .

4. The annealing separator according to claim 3 , wherein the particles comprising one or more elements selected from a group comprising Y, La, and Ce further comprise oxygen.

5. The annealing separator according to claim 3 , further comprising one or more elements selected from a group comprising Ti, Zr, and Hf.

6. A method for manufacturing grain-oriented electrical steel sheet comprising
a process for hot rolling a slab comprising, by mass %,
C: 0.100% or less,
Si: 2.5 to 4.5%,
Mn: 0.02 to 0.20%,
one or more elements selected from the group comprised of S and Se: total of 0.005 to 0.070%,
sol. Al: 0.005 to 0.050%, and
N: 0.001 to 0.030% and

having a balance comprised of Fe and impurities
to manufacture hot rolled steel sheet,
a process of cold rolling the hot rolled steel sheet by a cold rolling rate of 80% or more to manufacture cold rolled steel sheet,
a process of decarburization annealing the cold rolled steel sheet to manufacture decarburization annealed sheet,
a process of coating a surface of the decarburization annealed sheet with an aqueous slurry and drying the sheet, and
a process of finish annealing the steel sheet after the aqueous slurry has dried, wherein
the aqueous slurry comprises an annealing separator of claim 3 .

7. The method for manufacturing grain-oriented electrical steel sheet according to claim 6 , wherein the slab further comprises, in place of part of the Fe, one or more elements selected from a group comprised of Bi, Te, and Pb in a total of 0.030% or less.

8. The method for manufacturing grain-oriented electrical steel sheet according to claim 6 , wherein the slab further comprises, in place of part of the Fe, one or more elements selected from a group comprised of Cu, Sn, and Sb in a total of 0.60% or less.

9. A method for manufacturing finish annealing-use steel sheet for manufacturing grain-oriented electrical steel sheet according to claim 1 , comprising
a process for hot rolling a slab comprising, by mass %,
C: 0.100% or less,
Si: 2.5 to 4.5%,
Mn: 0.02 to 0.20%,
one or more elements selected from the group comprised of S and Se: total of 0.005 to 0.070%,
sol. Al: 0.005 to 0.050%, and
N: 0.001 to 0.030% and

having a balance comprised of Fe and impurities
to manufacture hot rolled steel sheet,
a process of cold rolling the hot rolled steel sheet by a cold rolling rate of 80% or more to manufacture cold rolled steel sheet,
a process of decarburization annealing the cold rolled steel sheet to manufacture decarburization annealed sheet, and
a process of coating a surface of the decarburization annealed sheet with an aqueous slurry and drying the sheet, wherein
the aqueous slurry comprises an annealing separator having MgO as a main constituent,
which the annealing separator comprising one or more elements selected from a group comprising Y, La, and Ce and one or more elements selected from a group comprising Ca, Sr, and Ba,
when expressing ratios of contents of Mg, Y, La, Ce, Ca, Sr, and Ba to the content of MgO (mass %) as respectively [Mg], [Y],

Assignees

• Nippon Steel Corp

Inventors

• Yamagata Ryutaro
• Morishige Nobusato
• Tanaka Ichiro

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

• H01F1/14766

  Fe-Si based alloys · CPC title

• C22C38/60

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

• C22C38/16

  containing copper · CPC title

• C22C38/06

  containing aluminium · CPC title