US 12,580,107 B2Granted

Grain oriented electrical steel sheet and producing method thereof

AssigneeNippon Steel Corporation

InventorsTakashi Kataoka, Yoshiyuki Ushigami, Shuichi Nakamura, Hiroyasu Fujii, Yoichi Zaizen

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Abstract

A grain oriented electrical steel sheet includes: by mass %, 0.010% or less of C; 2.50 to 4.00% of Si; 0.0010 to 0.0100% of acid soluble Al; 0.012% or less of N; 1.00% or less of Mn; 0.02% or less of S; and a balance comprising Fe and impurities, and has a tension-insulation coating at steel sheet surface and a SiO2 intermediate oxide film layer with an average thickness of 1.0 nm to 1.0 μm at an interface between the tension-insulation coating and the steel sheet surface. In the grain oriented electrical steel, a time differential curve fM(t) of a glow discharge optical emission spectrum of a metallic element M (Al) in the SiO2 intermediate oxide film layer satisfies a predetermined condition.

Claims4

Dependent claims

A method for producing a grain oriented electrical steel sheet comprising:

a base steel sheet;
an intermediate oxide film layer which is arranged on the base steel sheet, includes SiO2, and has an average thickness of 1.0 nm to 1.0 μm;
and
a tension-insulation coating which is arranged on the intermediate oxide film layer,
wherein the base steel sheet includes:
as a chemical composition, by mass %,
0.010% or less of C;
2.50 to 4.00% of Si;
0.0010 to 0.0100% of acid soluble Al;
0.012% or less of N;
1.00% or less of Mn;
0.02% or less of S;
and
a balance comprising Fe and impurities, and
wherein a time differential curve fM(t) of a glow discharge optical emission spectrum of a metallic element M (M:
Al) in the intermediate oxide film layer satisfies a following formula (1),
[
Formula
⁢
1
]

∫
T
p
T
f
f
A
⁢
1
(
t
)
⁢
dt
>
0
(
1
)
Tp:
a time t (second) corresponding to a local minimum value of a second-order time differential curve of a glow discharge optical emission spectrum of Si,
Tf:
a time t (second) corresponding to 2Tp−Ts when Ts is an analysis starting point of a glow discharge optical emission spectrum of Si, and
an area fraction of remained coating is 80% or more, the area fraction being evaluated by rolling a test piece around a cylinder with 20 mm of diameter and measuring the area fraction after bending 180°,
the method comprising
an oxide film layer forming process of forming an intermediate oxide film layer on a steel sheet,
wherein, in the oxide film layer forming process,
an annealing is conducted under conditions such that an annealing temperature T1 is 600 to 1200° C., an annealing time is 5 to 1200 seconds, an oxidation degree PH2O/PH2 is 0.15 or less, and an average heating rate HR2 in a temperature range of 600° C. to T1 is 5 to 50° C./second, and
after the annealing, an average cooling rate CR1 in a temperature range of T2 to T1 is 50° C./second or less, and an average cooling rate CR2 in a temperature range of 100° C. or more and less than T2 is slower than CR1, wherein T2 is a temperature expressed in T1-100° C.

48 more elements

A method for producing a grain oriented electrical steel sheet comprising:

a base steel sheet;
an intermediate oxide film layer which is arranged on the base steel sheet, includes SiO2, and has an average thickness of 1.0 nm to 1.0 μm;
and
a tension-insulation coating which is arranged on the intermediate oxide film layer,
wherein the base steel sheet includes:
as a chemical composition, by mass %,
0.010% or less of C;
2.50 to 4.00% of Si;
0.0010 to 0.0100% of acid soluble Al;
0.012% or less of N;
1.00% or less of Mn;
0.02% or less of S;
and
a balance comprising Fe and impurities, and
wherein a time differential curve fM(t) of a glow discharge optical emission spectrum of a metallic element M (M:
Al) in the intermediate oxide film layer satisfies a following formula (1),
[Formula 1]
∫
T
p
T
f
f
A
⁢
1
(
t
)
⁢
dt
>
0
(
1
)
Tp:
a time t (second) corresponding to a local minimum value of a second-order time differential curve of a glow discharge optical emission spectrum of Si,
Tf:
a time t (second) corresponding to 2Tp−Ts when Ts is an analysis starting point of a glow discharge optical emission spectrum of Si, and
an area fraction of remained coating is 80% or more, the area fraction being evaluated by rolling a test piece around a cylinder with 20 mm of diameter and measuring the area fraction after bending 180°,
wherein the base steel sheet further includes:
as the chemical composition, by mass %, at least one selected from
0.01 to 0.50% of Cr;
0.01 to 0.50% of Cu;
and
0.001 to 0.05% of Ca, and
wherein a time differential curve fM(t) of a glow discharge optical emission spectrum of a metallic element M (M:
Cr, Cu, Ca) in the intermediate oxide film layer including SiO2 satisfies at least one selected from following formulas (2) to (4),
[
Formulas
⁢
2
⁢
to
⁢
4
]

∫
T
p
T
f
f
Cr
(
t
)
⁢
dt
>
0
(
2
)
∫
T
p
T
f
f
Cu
(
t
)
⁢
dt
>
0
(
3
)
∫
T
p
T
f
f
Cu
(
t
)
⁢
dt
>
0
(
4
)
the method comprising
an oxide film layer forming process of forming an intermediate oxide film layer on a steel sheet,
wherein, in the oxide film layer forming process,
an annealing is conducted under conditions such that an annealing temperature T1 is 600 to 1200° C., an annealing time is 5 to 1200 seconds, an oxidation degree PH2O/PH2 is 0.15 or less, and an average heating rate HR2 in a temperature range of 600° C. to T1 is 5 to 50° C./second, and
after the annealing, an average cooling rate CR1 in a temperature range of T2 to T1 is 50° C./second or less, and an average cooling rate CR2 in a temperature range of 100° C. or more and less than T2 is slower than CR1, wherein T2 is a temperature expressed in T1-100° C.

112 more elements

A method for producing a grain oriented electrical steel sheet comprising:

a base steel sheet;
an intermediate oxide film layer which is arranged on the base steel sheet, includes SiO2, and has an average thickness of 1.0 nm to 1.0 μm;
and
a tension-insulation coating which is arranged on the intermediate oxide film layer,
wherein the base steel sheet includes:
as a chemical composition, by mass %,
0.010% or less of C;
2.50 to 4.00% of Si;
0.0010 to 0.0100% of acid soluble Al;
0.012% or less of N;
1.00% or less of Mn;
0.02% or less of S;
and
a balance comprising Fe and impurities, and
wherein a time differential curve fM(t) of a glow discharge optical emission spectrum of a metallic element M (M:
Al) in the intermediate oxide film layer satisfies a following formula (1),
[
Formula
⁢
1
]

∫
T
p
T
f
f
A
⁢
1
(
t
)
⁢
dt
>
0
(
1
)
Tp:
a time t (second) corresponding to a local minimum value of a second-order time differential curve of a glow discharge optical emission spectrum of Si,
Tf:
a time t (second) corresponding to 2Tp−Ts when Ts is an analysis starting point of a glow discharge optical emission spectrum of Si, and
an area fraction of remained coating is 80% or more, the area fraction being evaluated by rolling a test piece around a cylinder with 20 mm of diameter and measuring the area fraction after bending 180°,
wherein the base steel sheet further includes:
as the chemical composition, by mass %, at least one selected from
0.01 to 0.20% of Sn;
and
0.001 to 0.010% of B,
the method comprising
an oxide film layer forming process of forming an intermediate oxide film layer on a steel sheet,
wherein, in the oxide film layer forming process,
an annealing is conducted under conditions such that an annealing temperature T1 is 600 to 1200° C., an annealing time is 5 to 1200 seconds, an oxidation degree PH2O/PH2 is 0.15 or less, and an average heating rate HR2 in a temperature range of 600° C. to T1 is 5 to 50° C./second, and
after the annealing, an average cooling rate CR1 in a temperature range of T2 to T1 is 50° C./second or less, and an average cooling rate CR2 in a temperature range of 100° C. or more and less than T2 is slower than CR1, wherein T2 is a temperature expressed in T1-100° C.

53 more elements

A method for producing a grain oriented electrical steel sheet comprising:

a base steel sheet;
an intermediate oxide film layer which is arranged on the base steel sheet, includes SiO2, and has an average thickness of 1.0 nm to 1.0 μm;
and
a tension-insulation coating which is arranged on the intermediate oxide film layer,
wherein the base steel sheet includes:
as a chemical composition, by mass %,
0.010% or less of C;
2.50 to 4.00% of Si;
0.0010 to 0.0100% of acid soluble Al;
0.012% or less of N;
1.00% or less of Mn;
0.02% or less of S;
and
a balance comprising Fe and impurities, and
wherein a time differential curve fM(t) of a glow discharge optical emission spectrum of a metallic element M (M:
Al) in the intermediate oxide film layer satisfies a following formula (1),
[
Formula
⁢
1
]

∫
T
p
T
f
f
A
⁢
1
(
t
)
⁢
dt
>
0
(
1
)
Tp:
a time t (second) corresponding to a local minimum value of a second-order time differential curve of a glow discharge optical emission spectrum of Si,
Tf:
a time t (second) corresponding to 2Tp−Ts when Ts is an analysis starting point of a glow discharge optical emission spectrum of Si, and
an area fraction of remained coating is 80% or more, the area fraction being evaluated by rolling a test piece around a cylinder with 20 mm of diameter and measuring the area fraction after bending 180°,
wherein the base steel sheet further includes:
as the chemical composition, by mass %, at least one selected from
0.01 to 0.50% of Cr;
0.01 to 0.50% of Cu;
and
0.001 to 0.05% of Ca, and
wherein a time differential curve fM(t) of a glow discharge optical emission spectrum of a metallic element M (M:
Cr, Cu, Ca) in the intermediate oxide film layer including SiO2 satisfies at least one selected from following formulas (2) to (4),
[Formulas 2 to 4]
∫
T
p
T
f
f
Cr
(
t
)
⁢
dt
>
0
(
2
)
∫
T
p
T
f
f
Cu
(
t
)
⁢
dt
>
0
(
3
)
∫
T
p
T
f
f
Cu
(
t
)
⁢
dt
>
0
(
4
)
wherein the base steel sheet further includes:
as the chemical composition, by mass %, at least one selected from
0.01 to 0.20% of Sn;
and
0.001 to 0.010% of B,
the method comprising
an oxide film layer forming process of forming an intermediate oxide film layer on a steel sheet,
wherein, in the oxide film layer forming process,
an annealing is conducted under conditions such that an annealing temperature T1 is 600 to 1200° C., an annealing time is 5 to 1200 seconds, an oxidation degree PH2O/PH2 is 0.15 or less, and an average heating rate HR2 in a temperature range of 600° C. to T1 is 5 to 50° C./second, and
after the annealing, an average cooling rate CR1 in a temperature range of T2 to T1 is 50° C./second or less, and an average cooling rate CR2 in a temperature range of 100° C. or more and less than T2 is slower than CR1, wherein T2 is a temperature expressed in T1-100° C.

113 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/259,119Filed 13 Jul 2018
Published: US 2021/0272728 A12 Sep 2021
Granted: 17 Mar 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification38 codes

H01F 1/147
Metals or alloys: alloys characterised by their composition
C21D 1/76
Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material: adjusting the composition of the atmosphere
C21D 6/008
Heat treatment of ferrous alloys: containing Si
C21D 8/1222
Characterised by the working steps: hot rolling