Grain-oriented electrical steel sheet and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-12553136-B2
Application number	US-202017421762-A
Country	US
Kind code	B2
Filing date	Jan 16, 2020
Priority date	Jan 16, 2019
Publication date	Feb 17, 2026
Grant date	Feb 17, 2026

Abstract

A grain-oriented electrical steel sheet includes a base steel sheet which contains Si and Mn, an intermediate layer which is disposed on a surface of the base steel sheet and contains a silicon oxide as a main component, and an insulation coating which is disposed on a surface of the intermediate layer. A final-annealed film is not substantially present on a surface of the base steel sheet. In a surface layer region of grain-oriented electrical steel sheet, a Mn-depletion layer having a valley portion of a Mn content in which a Mn content is lower than an average Mn content of the base steel sheet in a region deeper than the surface layer region is provided, and a Mn-rich layer having a peak portion of a Mn content in which a Mn content is higher than that in the valley portion of the Mn content is provided in a region closer to a surface of the insulation coating than the Mn-depletion layer.

First claim

The invention claimed is:

1 . A grain-oriented electrical steel sheet, comprising:
a base steel sheet, wherein the base steel sheet has a composition comprising, in mass %:
Si: 0.50% to 7.00%;
Mn: 0.05% to 1.00%;
C: 0.005% or less,
N: 0.0050% or less, and
optionally comprising,
acid-soluble Al: 0.0065% or less;
S and Se: 0.001% or less in total;
Bi: 0.010% or less;
B: 0.0080% or less;
Ti: 0.015% or less;
Nb: 0.020% or less;
V: 0.015% or less;
Sn: 0.50% or less;
Sb: 0.50% or less;
Cr: 0.30% or less;
Cu: 0.40% or less;
P: 0.50% or less;
Ni: 1.00% or less;
Mo: 0.10% or less; and
a remainder of Fe and impurities;
an intermediate layer which is disposed on a surface of the base steel sheet, the intermediate layer comprising an Fe content of less than 30 atomic %, a P content of less than 5 atomic %, a Si content of 20 atomic % or more and less than 50 atomic %, an O content of 50 atomic % or more and less than 80 atomic %, and a Mg content of 10 atomic % or less; and an insulation coating which is disposed on a surface of the intermediate layer, wherein a final-annealed film is not present on a surface of the base steel sheet, and in a surface layer region,
a Mn-depleted layer having a valley portion of a Mn content in which a Mn content is lower than an average Mn content of the base steel sheet in a region deeper than the surface layer region is provided, and
a Mn-rich layer having a peak portion of a Mn content in which a Mn content is higher than that in the valley portion of the Mn content is provided in a region closer to a surface of the insulation coating than the Mn-depleted layer, and

wherein:
in a profile for a depth of a Mn standardized optical emission intensity calculated using the following Equations 1-1 and 1-2 from data of an optical emission intensity and a measurement time of Mn measured by a glow-discharge optical emission analysis for the grain-oriented electrical steel sheet, when a point having a maximum depth among points having a Mn standardized optical emission intensity of 0.9 is defined as a point A,
the surface layer region is a region from the surface of the insulation coating to a depth of the point A,
a point B at which the Mn standardized optical emission intensity is 0.50 or more and is the maximum is located in the surface layer region,
a point C at which the Mn standardized optical emission intensity is the minimum is located between the point A and the point B in the surface layer region,
the valley portion of the Mn content is a region having a depth of 0.1 μm before and after the point C,
the peak portion of the Mn content is a region having a depth of 0.1 μm before and after the point B, and
when an intermediate depth between the depth of the point B and the depth of the point C is defined as a boundary depth, and the Mn standardized optical emission intensity at the boundary depth is defined as a boundary Mn standardized optical emission intensity,
the Mn-depleted layer is a region from the boundary depth to the depth of the point A, and
the Mn-rich layer is present on the surface side of the insulation coating from the point B and is a region from a depth of a point having the same Mn standardized optical emission intensity as the boundary Mn standardized optical emission intensity to the boundary depth,
depth of d μm of each of measurement points=(measurement depth after measurement end, unit μm)/(time until measurement end, unit seconds)×(measurement time of measurement point, unit seconds),  Equation 1-1:

Mn standardized optical emission intensity at depth of d μm=(optical emission intensity of Mn at depth of d μm)/(average optical emission intensity of Mn at depth of 25 μm to 30 μm).  Equation 1-2:

2 . The grain-oriented electrical steel sheet according to claim 1 , wherein the point B and the point C in the surface layer region satisfy a relationship of the following Equation 2,
(Mn standardized optical emission intensity at point B )−(Mn standardized optical emission intensity at point C )≥0.05.  Equation 2:

3 . The grain-oriented electrical steel sheet according to claim 1 , wherein a distance between the point A and the point B in a depth direction calculated from the following Equation 3 is 0 to 10.0 μm,
distance between point A and point B in depth direction in unit μm=(depth at point B , unit μm)−(depth at point A , unit μm).  Equation 3:

4 . The grain-oriented electrical steel sheet according to claim 1 , wherein:
the insulation coating contains no Si, in a profile for a depth of a Si standardized optical emission intensity calculated using the following Equations 2-1 and 2-2 from data of an optical emission intensity and a measurement time of Si measured by the glow-discharge optical emission analysis for the grain-oriented electrical steel sheet, the surface layer region has a point D at which the Si standardized optical emission intensity is the maximum, and a distance between the point B and the point D in the depth direction calculated from the following Equation 4 is 0 to 1.0 μm,
depth d μm of each of measurement points=(measurement depth after measurement end, unit μm)/(time until measurement end, unit seconds)×(measurement time of measurement point, unit seconds),  Equation 2-1:

Si standardized optical emission intensity at depth of d μm=(optical emission intensity of Si at depth of d μm)/(average optical emission intensity of Si at depth of 25 μm to 30 μm),  Equation 2-2:

distance in unit μm between point B and point D in depth direction=(depth at point B , unit μm)−(depth at point D , unit μm).  Equation 4:

5 . The grain-oriented electrical steel sheet according to claim 1 , wherein:
the insulation coating contains Si, when, in a profile for a depth of a Si standardized optical emission intensity calculated using the following Equations 2-1 and 2-2 from data of an optical emission intensity and a measurement time of Si measured by the glow-discharge optical emission analysis for the grain-oriented electrical steel sheet, and a profile for a depth of a Si difference quotient calculated using the following Equation 5-1, in the surface layer region, in a region in which the Si difference quotient is a negative value, a point at which the Si difference quotient is the minimum and the Si difference quotient is −0.5 or less is defined as a point V, and a point at which the Si difference quotient is the maximum, is present on the surface side of the insulation coating from the point V, and is closest to the point V is defined as a point Z, and in a profile for a depth of a Mn difference quotient calculated from the Mn standardized optical emission intensity using the following Equation 5-2, in the surface layer region, a point at which the Mn difference quotient is maximum is defined as a point Y, and a point at which the Mn difference quotient is minimum is defined as a point X, and a point which is present in a region from the point X to the point Y and at which the Mn difference quotient is 0 is defined as a point W, a distance between the point W and the point Z in the depth direction calculated from the following Equation 6 is 0 to 1.0 μm, and the Mn difference quotient at the point Y and the Mn difference quotient at the point X satisfy a relationship of the following Equation 7,
depth d μm of each of measurement points=(measurement depth after measurement end, unit μm)/(time until measurement end, unit seconds)×(measurement time of measurement point, unit seconds),  Equation 2-1:

Si standardized optical emission intensity at depth of d μm=(optical emission intensity of Si at depth of d μm)/(average optical emission intensity of Si at depth of 25 μm to 30 μm),  Equation 2-2:

Si difference quotient

Assignees

• Nippon Steel Corp

Inventors

• Yamamoto Shinji
• Ushigami Yoshiyuki
• TAKATANI Shinsuke
• Nakamura Shuichi

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C21D2201/05

  Grain orientation · CPC title

• C21D9/46 Primary

  for sheet metals · CPC title

• C21D8/0236

  Cold rolling · CPC title

• C21D8/0226

  Hot rolling · CPC title