JPH0372026A - Production of grain-oriented silicon steel sheet having high magnetic flux density and remarkably excellent in iron loss - Google Patents

Abstract

PURPOSE:To produce the silicon steel sheet remarkably excellent in iron loss by artificially applying magnetic domain controlling treatment, in a direction perpendicular to rolling direction, to the surface of a steel sheet containing specific amounts of Sn and Ni in combination and having a tension coating. CONSTITUTION:A strip having a composition consisting of, by weight, 0.065-0.120% C, 2.8-4.5% Si, 0.045-0.100% Mn, 0.015-0.060% S and/or Se, 0.0150-0.0400% acid-soluble Al, 0.0050-0.0100% N, 0.03-0.25% Sn, 0.35-2.0% Ni, 0.03-0.25% Cu and/or 0.005-0.035% Sb, and the balance Fe with inevitable impurities is formed by means of rapid solidification. Before or after the flattening annealing of the above strip, tension coating is performed, and then, after secondary recrystallization, magnetic domain controlling treatment is artificially applied to the surface of the steel sheet in a direction practically perpendicular to the rolling direction. By this method, the grain-oriented silicon steel sheet with high magnetic flux density in which magnetic flux density at 800A/m magnetizing force is regulated to >=1.88T and iron loss is remarkably improved can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a high magnetic flux density unidirectional electrical steel sheet with significantly superior core loss, in which the surface of the steel sheet is subjected to magnetic domain control treatment, and a method for manufacturing the same.

[Prior Art] A method is known in which iron loss is reduced by artificially applying magnetic domain control treatment to the surface of a high magnetic flux density unidirectional electrical steel sheet in a direction substantially perpendicular to the rolling direction. That is, the method of irradiating laser beams at intervals in JP-A-55-18566 and JP-A-58-73724, the method of forming interstitial bodies at intervals in JP-A-61-96036; Kaisho 61-11721
A method of forming grooves at intervals, as disclosed in Publication No. 8;
JP-A No. 61-117284 discloses a method of removing a portion of the base steel at intervals and applying a phosphoric acid-based tension coating, and JP-A No. 61151511 discloses a method of irradiating plasma flame at intervals. Disclosed.

[Problem to be solved by the invention] By applying the above-mentioned artificial magnetic domain control technology, it has become possible to considerably improve the iron loss of high magnetic flux density unidirectional electrical steel sheets, and it is possible to significantly improve the iron loss of transformers using this. Through this, we were able to contribute to energy conservation, which is an issue of the times.

However, since then, the demands of the times for energy conservation have become even stronger, and it has become necessary to further improve the performance of grain-oriented electrical steel sheets, which are materials for transformers.

[Means to solve the problem]

The feature of the present invention is that the surface of a high magnetic flux density unidirectional electrical steel sheet containing a specific amount of Sn and Ni in combination and having a tension coating is artificially subjected to magnetic domain control treatment in a direction substantially perpendicular to the rolling direction. By applying this, a product with significantly superior iron loss can be obtained.

In the above, when the product contains a specific amount of Cu,
A product with particularly excellent iron loss can be obtained. In addition, when the average grain size of the product crystal grains in the rolling plane is 11 to 50 m/m,
A product with particularly excellent iron loss can be obtained.

The circumstances leading to the present invention will be explained below based on experimental results.

[Experiment■]

C: o, oso%, Si: 3.25%, Mn:
0.075%, P: 0.0050%, S:
0.025%, acid soluble All2 0.0250%, N
: 0.0085%, Sn: No additive and o, oi~0
．． A large number of thin cast slabs each having a thickness of 1.4 m/m were produced by a rapid solidification method, consisting of 34% Ni, no additives, and 0.05 to 3.0%, the remainder substantially Fe. Thin slabs heated to 1100℃
The sample was annealed for 120 seconds and cooled to room temperature at a rate of 30°C/second.

Then, it was cold rolled to a thickness of 0.170 m/m. During cold rolling, holding at 200° C. for 5 minutes was performed 5 times. Then 75%
)I! , 8 in an atmosphere of 25% N2 and a dew point of 65°C.
Decarburization annealing was performed at 50°C for 150 seconds. Next, an annealing separator containing magnesha as the main component is applied to reduce the temperature to 85% 11□
.

1 at a heating rate of 20°C/hour in an atmosphere of 15% N2.
heated to 200°C and then heated to 1200°C in an H2 atmosphere.
After soaking at ℃ for 20 hours, cooling and removing the annealing separator,
Tension coating was performed. Next, an energy density of 2. OJ/d,
A pulse laser was irradiated with an irradiation width of 0.25 m/m and an irradiation interval of 5 m/m, and the magnetic flux density B8 (magnetic flux density at a magnetizing force of 800 A/m) and iron loss W15150 were measured. In addition, the components of the product board (excluding coating and glass) were analyzed. Figure 1 shows the relationship between the Sn and Ni contents of the product board and W15150.

In Figure 1, the horizontal axis is the Sn content, and the vertical axis is the Ni content.
content. W15150 is coded (◎, ○.

Indicated by Δ, ×). In Fig. 1, excellent iron loss can be obtained in the region surrounded by straight line ABCD, that is, in the case of Sn: 0.03 to 0.25% and Ni: 0.35 to 2.0%. has become clear. Also, straight line abcd
The area surrounded by Sn: 0.05 to 0.
20% and Ni: 0.50 to 1.5%,
It has become clear that particularly excellent iron loss can be obtained. In addition, in the area surrounded by straight line ABCD, B8 is 1
．． It was over 88T.

[Experiment■]

C: 0.082%, Si: 3.25%, Mn:
0.075%, P: 0.0050%, S:
0.025%, acid soluble Ae: 0.0245%, N
: 0.0085%, Sn: 0.13%, Ni: 0.
A large number of thin cast slabs with a thickness of 1.4 m/m were produced by a rapid solidification method, containing 8% Cu, no additives, and 0.01 to 0.20%, the remainder substantially Fe. 11 thin slabs
It was annealed at 20° C. for 90 seconds and cooled to room temperature at 30″C/second.

Then, it was cold rolled to a thickness of 0.170 m/m. During cold rolling, holding was carried out four times for 5 minutes at 250''C.
%Hz, 25%Nt, in an atmosphere with a dew point of 65°C, 8
Decarburization annealing was performed at 50°C for 150 seconds. Next, an annealing separator containing magnesia as a main component was applied to give 85% Ih.

1 at a heating rate of 20°C/hour in an atmosphere of 15% N2.
heated to 200°C and then heated to 1200°C in an H2 atmosphere.
After soaking at ℃ for 20 hours, cooling and removing the annealing separator,
Tension coating was performed. Next, an energy density of 2. OJ/cd
A pulsed laser was irradiated with an irradiation width of 0.25 m/m and an irradiation interval of 5 m/m, and the magnetic flux density B8 (magnetic flux density at a magnetizing force of 800 A/m) and iron loss W15150 were measured. or,
The components of the product board (excluding coating and glass) were analyzed. Figure 2 shows the relationship between Cu content and iron loss.

In Figure 2, the horizontal axis is the Cu content, and the vertical axis is the Cu content.
This is the amount of change in W15150 due to addition.

As is clear from Figure 2, Cu: 0.03-0
．． An improvement in iron loss is recognized within the range of 0.08%. In addition, B8
were all 1.88T or more.

[Experiment ■] C: 0.080%, Si: 3.23%, Mn:
0.070%, P: 0.0030%, S:
0.025%, acid soluble A1: 0.0240%, N:
0.0085%, Sn:O, 13%, Ni: 0.7
%, remainder: substantially consisting of Fe, 0.80 to 2.80
A large number of thin slabs with a thickness of m/m were produced by a rapid solidification method.

The thin slab was annealed at 1080 to 1140°C for 90 seconds and cooled to room temperature at a rate of 35°C/second. Then plate thickness 0.170m/m
Cold-rolled until During cold rolling, holding at 220° C. for 5 minutes was performed 5 times. Next, decarburization annealing was performed at 850°C for 150 seconds in an atmosphere of 75% 11□, 25% N2, and a dew point of 65°C. Next, an annealing separator containing magnesia as a main component was applied, and the material was wound to a radius of curvature of 400 m/m. Then, in an atmosphere of 85% Hz and 15% N2 at 20°C/
The sample was heated to 1200° C. at a temperature increase rate of 1 hour, then soaked at 1200° C. for 20 hours in an Hz atmosphere, cooled, the annealing separator was removed, tension coating was performed, and flattening annealing was performed. Next, an energy density of 2, OJ/cIi!, is applied to the surface of the steel plate in a direction perpendicular to the rolling direction. , irradiation width 0
．． A pulse laser was irradiated at 25 m/m with an irradiation interval of 5'm and 7 m, and the magnetic flux density B8 (magnetic flux density at a magnetizing force of 800 A/m) and iron loss W15150 were measured. Then,
The surface coating was removed, and the grain size of the secondary recrystallized grains in the rolling plane was measured by the line segment method in the rolling direction, 45° direction to the rolling direction, and 90' direction to the rolling direction, and the average grain size was determined. (All average particle diameters related to the present invention are determined by this method)
.

The relationship between the average particle diameter and B8 and W15150 is shown in FIG. In Figure 3, the horizontal axis is the average particle size, and the vertical axis is B
8 and W15150. As is clear from FIG. 3, especially excellent iron loss was obtained when the average grain size was 11 to 50 m/m.

From the results of Experiments I to II, Sn: 0.03 to 0.
．． 25 and Ni: 0.35 to 2.0%, preferably Cu: 0.03 to 0.08%, and preferably the average grain size of secondary recrystallized grains in the rolling surface is 11%. ~5
0 m/m, with a tension coating, on the surface of the steel plate after secondary recrystallization in a direction almost perpendicular to the rolling direction,
Magnetizing force 800A/m artificially performed by magnetic domain control processing
It has become clear that a significantly superior iron loss can be obtained in a high magnetic flux density unidirectional electrical M1 steel sheet with a magnetic flux density of 1.887 or higher.

The present inventor used MnS, MnSe as an inhibitor.
.

Experiments similar to those in Experiments I to II were also conducted for the one-time cold rolling method and the two-time cold rolling method using one or more selected from CuxS+Sb+Al2N, and similar results were obtained.

[Experiment■]

C: 0.030-0.150%, Si: 3.25%
, Mn: 0.070%, P: 0.0035%, S
: 0.026%, acid soluble A170.0245%
, N: 0.0086%, Sn: 0.12%, Ni:
0.7%, balance: substantially Fe, 2.3 m
A large number of thin slabs with thicknesses of 1.4 m/m and 1.4 m/m were produced by rapid solidification. 12 thin slabs at 1100'c
It was annealed for 0 seconds and cooled to room temperature at 35° C./second. then 2
, 3 m/m thick plate to 0.285 m/m, 1.4
The m/m thick plate was cold rolled to 0.170 m/m. During cold rolling, holding at 230° C. for 5 minutes was performed 5 times. Next, decarburization annealing was performed at 850°C for 150 to 300 seconds in an atmosphere of 75% Hz, 25% N2, and a dew point of 65°C. Next, an annealing separator containing magnesia as a main component was applied, and the temperature was heated at 20°C/in an atmosphere of 85% N2 and 15% N2.
The surface of the steel plate was heated to 1200 °C at a temperature increase rate of 1 hour, then soaked at 1200 °C for 20 hours in an H2 atmosphere, cooled, the annealing separator was removed, and a tension coating was applied to the surface of the steel plate. In the direction perpendicular to the rolling direction, the energy density 2. OJ/d, irradiation width 0.25m/m, irradiation interval 5
Irradiated with pulsed laser at m/m, magnetic flux density B8 (magnetic flux density at magnetizing force 800 A/m) and iron loss W15150
, W17150 was measured to investigate the secondary recrystallization status. The relationship between the C content, secondary recrystallization rate, and iron loss of the thin slab is shown in FIGS. 4 and 5.

Figure 4 shows the case where the product board thickness is 0.285 m/m.

In FIG. 4, the horizontal axis is the C content, and the vertical axis is the secondary recrystallization rate and W17150.

FIG. 5 shows the case where the product board thickness is 0.170 m/m.

In FIG. 5, the horizontal axis is the C content, and the vertical axis is the secondary recrystallization rate and W15150.

As is clear from Figures 4 and 5, C: 0.065
Excellent iron loss was obtained in the range of ~0.120%. In addition,
All 88 in this range were 1.88 T or more.

[Experiment V]

C: 0.082%, Si: 3.25%, Mn:
0.072%, p: o, ooso%, S: 0
．． 025%, acid soluble Al: 0.0250%, N:
0.0085%, Sn: 0.13%, Ni: 0.8%
, Sb: no additive and 0.001 to 0.050%, and the remainder: substantially Fe, and a large number of thin slabs with a thickness of 1.4 m/m were produced by a rapid solidification method. 11 thin slabs
It was annealed at 00°C for 120 seconds and rapidly cooled to room temperature. Then, it was cold rolled to a thickness of 0.170 m/m. During cold rolling, 250
Holding for 5 minutes at ℃ was carried out five times. Then 75%L, 2
150°C at 850°C in an atmosphere of 5% N2 and a dew point of 65°C.
Decarburization annealing was performed for seconds. Next, an annealing separator containing magnesia as a main component was applied and heated to 1200°C at a temperature increase rate of 20°C/hour in an atmosphere of 85% N2 and 15% Nt, and then heated to 1200°C in an Hz atmosphere. After soaking for 20 hours, it was cooled, the annealing separator was removed, and tension coating was applied. Next, an energy density of 2, OJ/et, is applied to the surface of the steel plate in a direction perpendicular to the rolling direction.
a, pulsed laser irradiation with an irradiation width of 0.25 m/m and an irradiation interval of 5 m/m, and a magnetic flux density of B8 (800 A/m of m flower)
The magnetic flux density) and iron loss W15150 were measured. Figure 6 shows the relationship between the sb content and iron loss of the thin slab.

In Figure 6, the horizontal axis is the sb content, and the vertical axis is the sb content.
This is the amount of change in W15150 due to addition.

As is clear from Fig. 6, Sb: 0.005~
An improvement in iron loss was observed within a range of 0.035%. In addition,
B8 was all 1.88T or more.

From the results of Experiments I to V, the following became clear. C: 0.065-0.120%, Si:
2, 8-4.5%, Mn: 0.045-0.10
0%, S or Se or both: 0.01
5-0.060%, acid soluble Aj! : 0.0150
~0.0400%, N: 0.0050~0.010
0%, Sn: 0.03-0.25%, Ni:
Before the final cold rolling, a rapidly solidified thin slab containing 0.35 to 2.0%, the balance Fe and unavoidable impurities,
Annealing at 030 to 1200°C, heat treatment by rapid cooling after annealing, final cold rolling with a reduction rate of 83 to 92%, decarburization annealing in a humid atmosphere containing hydrogen, and annealing separation with magnesia as the main component. Coating agent, winding into a coil shape, high-temperature finish annealing, removing annealing separation agent, flattening annealing, tension coating before or after flattening annealing, and after secondary recrystallization, Before or after tension coating or flattening annealing, a magnetizing force of 800 A is achieved by artificially performing magnetic domain control treatment on the steel sheet surface in a direction approximately perpendicular to the rolling direction.
A high magnetic flux density unidirectional electrical steel sheet having a magnetic flux density of 1.88 T or more at /m and extremely excellent core loss can be obtained.

In addition, as a material component, in addition to the above, Cu: 0.03 to 0
．． By containing one or both of Sb: 0.005% to 0.035%, the iron loss is further improved.

In addition, the average grain size of product crystal grains in the rolling surface is set to 11 to 5.
By adjusting it to 0 m/m, the iron loss is further improved.

Next, reasons for limitations other than those described above regarding components and other conditions in the present invention will be described.

The ingredients of the thin slab are as follows. Hereinafter, % is weight %. St: 2.8 to 4.5% is desirable. 2
．． If it is less than 8%, good iron loss cannot be obtained, and if it exceeds 4.5%, workability is poor. Mn: 0.045-0.
100% is desirable. Less than 0.045% or 0.100
If the content exceeds 0.015% to 0.060%, good iron loss cannot be obtained.

If it is less than 0.015% or more than 0.060%, good iron loss cannot be obtained. Acid soluble Al: 0.0150-0.0
400% is desirable. If it is less than 0.0150%, good core loss cannot be obtained, and if it exceeds 0.0400%, secondary recrystallization becomes unstable.

N: Desirably 0.0050-0.0100%. 0
．． If it is less than 0.050%, secondary recrystallization is unstable;
If it exceeds 0.100%, blister defects will occur.

The thickness of the thin slab is preferably 0.2 to 10 m/m.

Q: If it is less than 2 m/m or more than 10 m/m, good magnetic properties cannot be obtained.

Before the final cold rolling, it is desirable to anneal at 1030 to 1200"C and rapidly cool after annealing. If the annealing temperature is less than 1030"C, good iron loss cannot be obtained, and if it exceeds 1200"C, secondary recrystallization will occur. Becomes unstable. Rapid cooling after annealing is necessary to obtain good product magnetic properties.

The reduction ratio in the final cold rolling is preferably 83 to 92%. If it is less than 83% or more than 92%, good iron loss cannot be obtained. During the final cold rolling, it is preferable to maintain the temperature between 150 and 300°C for 30 seconds or more. However, the effects of the present invention are not impaired even if warm holding is not performed during rolling.

High-temperature finish annealing requires high-temperature and long-term annealing for dulling, and after decarburization annealing, it is desirable to apply an annealing separator, wind it into a coil, and then annealing the coil in a pit shape. In this case, the radius of curvature of the inner circumference of the coil is 250 to 4
If it is less than 250m/m, there is a risk of deformation of the plate during winding, deterioration of iron loss during flattening annealing after secondary recrystallization, etc. If it exceeds 400m/m, equipment costs will increase. becomes higher.

It is desirable to perform tension coating before or after flattening annealing; good core loss cannot be obtained without tension coating.

After secondary recrystallization, before or after tension coating or flattening annealing, on the surface of the steel plate in a direction approximately perpendicular to the rolling direction.
It is desirable to perform magnetic domain control processing artificially, Tl11
If ward control treatment is not performed, good iron loss cannot be obtained.
Note that as for the method of magnetic domain control processing, known methods that have already been disclosed can be applied. As a known method,
For example, JP-A-55-18566, JP-A-58-
73724, a method of irradiating laser beams at intervals; a method of forming penetrating bodies at intervals, JP-A-61-96036;
1-117218, a method of forming grooves at intervals, and JP-A-61-117284, a method of removing a part of the base iron at intervals and applying a phosphoric acid-based tension coating, Examples include the method of irradiating plasma flame at intervals, as disclosed in Japanese Patent No. 62-151511.

The method for preparing the product crystal grain size in the rolling plane includes material composition, each annealing condition, final cold rolling condition, &I of the annealing separator.
However, any method is applicable.

Why iron loss is significantly improved when magnetic domain control treatment is applied to the surface of a high magnetic flux density unidirectional electrical steel sheet containing a specific amount of Sn and Ni and having a tension coating in a direction substantially perpendicular to the rolling direction. Although the clear reason for this is still unknown, due to the combined content of Sn and Ni,
It is thought that a change occurs in the base metal itself, between the base metal and the glass, or in the glass, resulting in an effect that minimizes the iron loss of the steel sheet after the magnetic domain control treatment.

The average grain size of product crystal grains in the rolling plane is 11 to 50 m.
The reason why a significantly superior iron loss is obtained in the range of /m is presumed as follows. When the average grain size is 10 m/m or less, fine grain boundaries are considered to be harmful to the magnetic domain formation pattern that minimizes core loss in the case of the magnetic domain control treated material according to the present invention.

When a steel plate is subjected to high-temperature finish annealing in a bent state, the reason why iron loss deteriorates when the average grain size exceeds 50 m/m is due to the deviation of the Goss orientation from the rolled surface due to flattening annealing after high-temperature finish annealing. It is thought that this is the case.

Examples are shown below.

〔Example〕

Example I C: 0.050%, 0.083% or 0.150%,
Si: 3625%, Mn: 0.070%, P:
0.0040%, S: no addition, 0.015% or 0.
025%, Se: no addition, 0.015% or 0.02
5%, acid soluble 1! : 0.0245%, N: 0
．． 0085%, Sn: no addition, 0.01%, 0.15
% or 0.30%, Ni: no addition, 0.05%, 0.
7% or 2.5%, Cu: no addition, 0.06% or 0
．． 20. Sb: No additive, 0.020% or 0.0
50%, balance: 0 containing Fe and unavoidable impurities
, thin slabs with a thickness of 90 to 3.25 m/m were produced by a rapid solidification method.

This thin slab was processed until the final cold rolling according to the manufacturing process I, U or (2) shown below.

In the case of manufacturing process ■, the thin slab is 1000~1220''
After annealing, the material was annealed at various temperatures between C and C for 90 seconds, cooled to room temperature at a rate of 35 C/sec, and then final cold rolled.

In the case of manufacturing process ■, the thin slab is heated to 1000-1220℃.
Annealed for 90 seconds at various temperatures between
Cooled at 5°C/sec, then subjected to intermediate cold rolling to various intermediate thicknesses, then intermediately annealed at 1000''C for 100 seconds, cooled to room temperature after annealing at 35°C/sec, then final Cold rolling was performed.

In the case of manufacturing process ■, thin slabs are heated at 1000″C for 100
Annealed for seconds, cooled to room temperature at 35°C/second after annealing, then intermediate cold rolled to various intermediate thicknesses, then 10
It was annealed for 90 seconds at various temperatures between 00 and 1220°C, and after annealing, it was cooled to room temperature at a rate of 35°C/second, and then final cold rolling was performed.

During the final cold rolling, rolling was carried out by performing warm holding at 250''C for 5 minutes five times and by not performing warm holding.

After the final cold rolling, decarburization annealing was performed at 850°C for 150 to 300 seconds in a humid atmosphere of 75% N2 and 25% N2,
Apply an annealing separator mainly composed of magnesia, and the radius of curvature is 4.
It was wound into a coil at a speed of 00 m/m and subjected to high-temperature finish annealing.

In high-temperature finish annealing, the atmosphere during temperature rise is 85% Ih.
, 15% N2, heating rate 25°C/hour, 120
The temperature was raised to 0"C, and the temperature was raised to 1200"C for 20 minutes in a hydrogen atmosphere.
Time annealed. Thereafter, the annealing separator was removed, and magnetic domain control treatment, tension coating, annealing, etc. were performed using the following four methods A, B, C, and D.

In method A, the tension per unit cross-sectional area of the steel plate is 1.0
kg/mm", and flattening annealing was performed at 850"C for 30 seconds to bake the coating, and the surface of the steel plate was coated with an energy density of 2.5 kg/mm'' in the direction perpendicular to the rolling direction. OJ/cf.

Pulse laser irradiation was performed with an irradiation width of 0.25 m/m and an irradiation interval of 5 m/m.

In Method B, after processing in Method A, sb metal powder was applied and annealed at 800''C for 2 hours.

In method C, an energy density of 3. OJ /c1i1, irradiation width 0
, 2 m/m, irradiation interval 5 m/m, pulsed laser irradiation to partially remove the forsterite layer, and immersion in 61% nitric acid solution for 20 seconds to determine the tension per unit cross-sectional area of the steel plate. 1. Tension coating is performed to obtain 85 kg/m'', and the coating is baked.
Flattening annealing was performed at 0° C. for 30 seconds.

In the D method, the gear pitch is 8 m/m, the gear tip curvature radius is 100 I, and the blade inclination is 75° with respect to the rolling direction.
With the gear type roll, the load is 180kg/flII.
Strain is introduced at step 12, and the tension per unit cross-sectional area of the steel plate is 1.
．． Tension coating was carried out to obtain Okg/mn+2, and the coating was baked at 850℃ for 30 minutes.
A flattening annealing was performed for seconds.

After processing by method A, method B, method C, or method D, measure the magnetic flux density B8 and iron loss, and then remove the surface coating,
After pickling, the average grain size of the secondary recrystallized grains in the rolling plane was measured. Components of thin slabs, thickness of thin slabs, manufacturing process (
1, II or III), temperature of thin slab annealing, plate thickness after intermediate cold rolling, temperature of intermediate annealing, plate thickness after final cold rolling, rolling reduction ratio of final cold rolling, warm temperature during final cold rolling Presence of retention, presence or absence of tension coating, average grain size of product crystal grains, magnetic domain control method (A
.

B, C or D), magnetic flux density B8, and iron loss are shown in Table 1.

As is clear from Table 1, in the case of the example of the present invention, a high magnetic flux density unidirectional electromagnetic control plate with significantly excellent iron loss was obtained.

〔Effect of the invention〕

The present invention makes it possible to supply materials such as iron cores for transformers with extremely low iron loss, and the energy loss of electrical equipment such as transformers can be significantly reduced, resulting in great economic effects.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the Sn and Ni contents of the steel sheet and iron loss for a grain-oriented electrical steel sheet that has a tension coating and has undergone magnetic domain control treatment on the surface of the steel sheet after secondary recrystallization. be. Figure 2 shows a high magnetic flux density unidirectional electrical steel sheet that contains a predetermined amount of Sn and Ni, has a tension coating, and has undergone magnetic domain control treatment on the surface of the steel sheet after secondary recrystallization.
It is a figure showing the change of iron loss accompanying Cu content of a steel plate. Figure 3 shows a material containing a predetermined amount of Sn and Ni, bent to a radius of curvature of 400 m/m, high-temperature finish annealing, secondary recrystallization, flattening annealing, tension coating, and secondary recrystallization. FIG. 2 is a diagram showing the relationship between the average grain size of product crystal grains, magnetic flux density, and iron loss for a grain-oriented electrical steel sheet whose surface has been subjected to magnetic domain control treatment after crystallization. Figure 4 shows a unidirectional electrical steel sheet with a thickness of 0.285 m/m that contains a predetermined amount of Sn and Ni, has a tension coating, and has undergone magnetic domain control treatment on the surface of the steel sheet after secondary recrystallization. FIG. 2 is a diagram showing the relationship between the C content at the stage of thin cast slab, secondary recrystallization rate, and iron loss of the product. Figure 5 shows a unidirectional electromagnetic plate yI-0.170 m/m containing a predetermined amount of Sn and Ni, having a tension coating, and having undergone magnetic domain control treatment on the surface of the steel plate after secondary recrystallization. It is a figure which shows the relationship between the C content at the stage of a thin cast slab, the secondary recrystallization rate of a product, and iron loss about a steel plate. Figure 6 shows a unidirectional electrical steel sheet containing a predetermined amount of Sn and Ni, having a tension coating, and having undergone magnetic domain control treatment on the surface of the steel sheet after secondary recrystallization, at the stage of thin slab. It is a figure which shows the change of iron loss accompanying sb content. Figure 4 C content (%) Figure procedural amendment (voluntary) March 1990 Nog

Claims (3)

[Claims] (1) C: 0.065 to 0.120% or less, S by weight%
i: 2.8-4.5%, Mn: 0.045-0.100
%, S or Se or both: 0.015 to 0
．． 060%, acid-soluble Al: 0.0150-0.040
0%, N: 0.0050-0.0100%, Sn: 0.
03-0.25%, Ni: 0.35-2.0%, balance:
A thin slab containing Fe and unavoidable impurities by rapid solidification is annealed at 1030 to 1200°C before final cold rolling,
After annealing, heat treatment is performed to rapidly cool the material, final cold rolling is performed at a rolling reduction of 83 to 92%, decarburization annealing is performed in a humid atmosphere containing hydrogen, an annealing separation agent containing magnesia as the main component is applied, and the material is shaped into a coil. Coiling, high-temperature finishing annealing, removing the annealing separator, flattening annealing, applying tension coating before or after flattening annealing, after secondary recrystallization, before or after tension coating or flattening annealing. Afterwards, a magnetic domain control treatment is artificially applied to the surface of the steel plate in a direction almost perpendicular to the rolling direction, and the magnetic flux density at a magnetizing force of 800 A/m is 1.88 T or more and the iron loss is significantly superior. A method for manufacturing high magnetic flux density unidirectional electrical steel sheets. (2) C: 0.065-0.120%, Si: in weight%
2.8-4.5%, Mn: 0.045-0.100%,
Either or both of S or Se: 0.015 to 0.0
60%, acid-soluble Al: 0.0150-0.0400%
, N: 0.0050-0.0100%, Sn: 0.03
~0.25%, Ni: 0.35-2.0%, and Cu:
0.03-0.08%, Sb: 0.005-0.035
%, the balance: Fe and unavoidable impurities, before the final cold rolling,
Annealing at 1030 to 1200°C, heat treatment by rapid cooling after annealing, final cold rolling at a reduction rate of 83 to 92%, decarburization annealing in a humid atmosphere containing hydrogen, and annealing separation with magnesia as the main component. Coat the agent, wind it into a coil, perform high-temperature finishing annealing, remove the annealing separation agent, perform flattening annealing, apply tension coating before or after flattening annealing, and after secondary recrystallization, apply tension coating. A magnetic flux density of 1.88 T or more at a magnetizing force of 800 A/m, characterized by artificially performing magnetic domain control treatment on the steel plate surface in a direction substantially perpendicular to the rolling direction, before or after coating or flattening annealing. in,
A method for manufacturing a high magnetic flux density unidirectional electrical steel sheet with significantly superior iron loss. (3) The average grain size of product crystal grains in the rolling plane is 11~
Claim 1 or 2, characterized in that it is adjusted to 50 m/m.
The method described in.