JPH01176034A - Production of grain-oriented magnetic steel sheet having excellent magnetic characteristic - Google Patents

Abstract

PURPOSE:To easily produce the title grain-oriented magnetic steel sheet having an excellent magnetic characteristic by appropriately welding the same oriented material to the edge of a steel sheet, and applying specified straining and annealing prior to the final finish annealing of a silicon-contg. cold-rolled steel sheet. CONSTITUTION:The hot rolling and cold rolling of a silicon-contg. steel slab, decarburization, and primary recrystallization annealing are applied. The same oriented material is welded to the edge of the steel sheet with the [001] axis inclined toward the rolling direction of the steel sheet at <=10 deg.C. The stepwise straining toward the inside of the base steel sheet from the weld zone and annealing are successively or thereafter applied plural times to the part of the steel sheet which is not secondarily recrystallized, and the secondarily recrystallized grain is grown. Final finish annealing is then applied to the steel sheet. After the final finish annealing, the oxide on the steel sheet surface is removed, as required, the steel sheet is specularly ground to 0.4mum Ra average roughness on the center line, and then an ultrathin coating film of the nitride, carbide, or oxide of a metal is formed on the specularly ground surface. By this method, a grain-oriented magnetic steel sheet having excellent magnetic characteristics, especially magnetic flux density and iron loss, is stably obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing unidirectional electrical steel sheets with excellent magnetic properties, and in particular, the present invention relates to a method for manufacturing unidirectional electrical steel sheets with excellent magnetic properties, and in particular, to effectively control the growth process from the nucleation of Goss-oriented secondary recrystallized grains. The aim is to achieve stable improvements in magnetic properties, particularly magnetic flux density, and even iron loss by controlling the magnetic flux density.

(Prior art) As is well known, unidirectional silicon steel sheets are mainly used in transformers,
These unidirectional silicon steel sheets are used as iron cores in other electrical equipment, and have excellent magnetic properties in the rolling direction, that is, they have a B10 value (magnetic field) as magnetic properties (excitation properties). The magnetic flux density represented by the magnetic flux density in the rolling direction generated when the strength of It is required that the iron loss represented by /So value (iron loss when magnetized at a magnetic flux density of 1.7 T and a frequency of 5011z) is low.

In order to improve the magnetic properties of the unidirectional silicon steel sheet as described above, it is necessary to align the <001> axes of the secondary recrystallized grains in the steel sheet to a high degree in the rolling direction. For this purpose, M
In addition to fine precipitates such as nS and MnSe,
1-13469, a small amount of s
b, as well as As, Bi, Pb and Sn as disclosed in Japanese Patent Publication No. 54-32412, and a small amount of Mo etc. as disclosed in Japanese Patent Publication No. 57-14737. In addition, by appropriately combining the processing conditions of hot rolling and cold rolling to form a suitable primary recrystallization texture, recently the magnetic flux density B1° value has been improved at plate thickness: 0.30 mm. High magnetic flux density exceeding 1.907 and iron loss -1.7. The value is 1.05W
/kg or less unidirectional silicon steel sheets are now being manufactured.

(Problems to be Solved by the Invention) However, the following problems still remain in actual production on an industrial scale.

In other words, in order to highly align the <001> axis of the secondary recrystallized grains of the product in the rolling direction, it is necessary to adjust the ingredients, etc.
It is necessary to strictly control each of the complex and wide-ranging processes such as steel making, hot rolling, cold rolling, and heat treatment, but in actual factory production, the processing conditions easily deviate from the overall appropriate conditions as described above, and even a slight deviation may occur. However, because the orientation of the <001> axis in the rolling direction is poor, it has been difficult to stably obtain a grain-oriented electrical steel sheet with excellent B value and iron loss.

Furthermore, recently, attempts have been made to reduce the iron loss by reducing the thickness of the finished plate. In order to achieve stability, there was also a problem in that the iron loss improvement effect by reducing the plate thickness could not be stably obtained, and improvement of this problem was strongly desired.

In addition, it has been reported that when attempting to significantly reduce iron loss by reducing the thickness of the plate, it is necessary to strictly control the Goss grains in particular directions (for example, Japanese Patent Publication No. 57-61102 and IEEE , Transaction on Ma
gne-tics vol Mag-21* N111
(1985)), and in any case, there was a strong demand for the development of a method for stable and strict control of Goss grains in specific orientations.

This invention advantageously solves the above problems, (h
ko) By appropriately controlling the secondary recrystallized grains with the <001> orientation throughout the growth process from their nucleation, it is possible to effectively preferentially grow and stably improve the B1° value,
Furthermore, we will propose an advantageous manufacturing method for ultra-low iron loss unidirectional electrical steel sheets that can significantly improve magnetic properties through the synergistic effects of smoothing the steel sheet surface and effectively utilizing the ultra-thin tension-applying coating. purpose.

(Means for solving the problem) In order to highly align the <ooi> axes of the secondary recrystallized grains in the finished product in the rolling direction, it is necessary to improve the crystal structure, texture, inhibitor, etc. of the steel sheet before secondary recrystallization. It is necessary to maintain the proper conditions, and in order to achieve these conditions, we strictly control the complex and wide-ranging processing conditions, starting from the material composition, steel manufacturing, hot rolling, cold rolling, and heat treatment. In the next recrystallization annealing process, Goss-oriented grains with a high degree of aggregation are generated.
However, in actual production on an industrial scale, it is easy to deviate from the above comprehensive appropriate conditions, and if there is even a slight deviation, the orientation of the <001> axis in the rolling direction will deteriorate. Putting it away is as described above.

In response to this problem, the inventors conducted research on the secondary recrystallization phenomenon that determines the orientation of the <001> axis, focusing on the generation and growth of secondary recrystallization nuclei, which is the basis thereof.

As a result, it was found that the material properties of the steel sheet before secondary recrystallization, such as crystal structure, texture, and inhibitors, deviated somewhat from the conventional overall appropriate conditions due to actual variations or simplifications in the manufacturing process conditions. By adopting a unique manufacturing process that utilizes micro-strain introduction and subsequent heat treatment as well as the introduction of appropriate nuclei by welding the same material to the edge of the steel plate with controlled orientation, (hkO) <00
It was found that the nucleation and growth of secondary recrystallized grains in the 1> orientation are preferentially achieved.

Furthermore, in this case, the <001> axis of the secondary grains not only accumulates in a highly stable manner in the rolling direction, but also significantly improves not only the magnetic properties but also the manufacturing process. It is now possible to perform secondary recrystallization in a continuous furnace instead of annealing for a long time in a steel plate. It was also discovered that magnetic properties could be further improved if an ultra-thin coating made of carbonitride or other material was used to provide tension.

This invention is based on the above knowledge.

That is, the gist of the present invention is as follows.

(1) After hot rolling a silicon-containing steel slab and then cold rolling it once or twice or more with intermediate annealing in between,
In manufacturing unidirectional electrical steel sheets through a series of processes of decarburization and primary recrystallization annealing, and then final finish annealing, the edge of the steel plate is coated with the same type of directional material before the final finish annealing. The material (00
1) Welding under conditions such that the axis is within 10° with respect to the rolling direction of the steel plate, and then or thereafter, welding the non-secondary recrystallized area in stages from the welded area toward the inside of the base steel plate. A method for producing a grain-oriented electrical steel sheet with excellent magnetic properties, comprising the step of growing secondary recrystallized grains by repeating strain introduction and annealing multiple times.

(2) After hot rolling a silicon-containing steel slab and then cold rolling it once or twice or more with intermediate annealing in between,
In manufacturing unidirectional electrical steel sheets through a series of processes of decarburization and primary recrystallization annealing, and then final finish annealing, the edge of the steel plate is coated with the same type of directional material before the final finish annealing. The material (00
1) Welding under conditions such that the axis is within 10° with respect to the rolling direction of the steel plate, and then or thereafter, welding the non-secondary recrystallized area in stages from the welded area toward the inside of the base steel plate. It has a step of growing secondary recrystallized grains by repeating strain introduction and annealing multiple times, and after final annealing, removes oxides from the surface of the steel sheet, and then polishes it to a centerline average roughness Ra of 0. 4μm
After finishing the following mirror surface, Ti is deposited on the mirror finished surface by dry plating.

Nb, Si+V, Cr, Aj't Mn, B
+ Ni, Co, Mo, Zr.

Nitride and/or carbide of Ta, Hf, − and AN + St+ Mn, Mg, Zr, T
1. A method for producing a grain-oriented electrical steel sheet, comprising the step of forming an ultra-thin film consisting mainly of at least one kind of oxides selected from the group consisting of oxides of t.

Hereinafter, this invention will be specifically explained based on the basic experimental results that led to this invention.

C: 0.032gt% (hereinafter simply expressed as %), Si:
3.30%, Mn: 0.03% and Se: 0
．． A steel slab having a composition containing 1320%
After heating at C for 1 hour, hot rolling to a thickness of 2.3 mm, homogenization annealing at 900°C for 3 minutes, followed by intermediate annealing at 950°C for 3 minutes. After being cold-rolled twice to obtain a cold-rolled sheet with a final thickness of 0.23++m, it was decarburized in wet hydrogen at 820°C for 30 minutes.
Primary recrystallization annealing was performed.

The thus obtained material is subjected to secondary recrystallization annealing of the image material, with 3% uniform plastic strain introduced by rolling as material A, and material to which no such plastic strain is introduced as material B. The results of investigating temperature and time dependence are
Shown in Figure 1.

As is clear from Figure 1, when compared to material B, material A to which strain has been introduced has a secondary recrystallization onset temperature that is approximately 150°C lower when annealed for the same time, while the incubation period is lower when annealed at the same temperature. It is shortened to less than 1/100.

In addition, as a result of measuring the growth rate of secondary grains during annealing at 900"C, material A to which strain was introduced was 10% faster than material B.
It was found that they grow more than twice as fast.

From the above results, it has been found that by introducing strain into a steel sheet and annealing it, secondary recrystallized grains can be rapidly generated and grown.

Based on the above findings, the inventors further
The following experiment was conducted on the primary recrystallization annealed plate.

Thickness: 0.23 am, Radius: 30III11 Goss orientation single crystal plate (0011 axis is aligned with the rolling direction C of the steel plate, butt welded to both edges of the steel plate using a laser, and then to the welded part Strain introduction by laser irradiation and annealing by plasma jet were repeated, and the Goss orientation of the single crystal was grown by 2 mm toward the inside of the base steel plate, resulting in a C material.

Next, materials A and C were rolled to form a single crystal.
A strain of 1% deformation is introduced in a width of 5 mm from the boundary with the secondary recrystallized area toward the inside of the base steel plate, and then the whole is annealed at 950°C for 3 minutes, which is repeated. After the Goss orientation of the crystals was grown over the entire steel plate, oxides on the surface were removed by pickling.

After that, after rolling with a reduction rate of 1% for flattening,
Purification annealing was performed at 1200'C for 15 hours in soft hydrogen.

When the magnetic flux density of the thus obtained product plate was investigated, it was found that the A material had R3°-1,88 (T), and the C material had a R3°-1,985 (T).

As mentioned above, by using a single crystal with controlled orientation as a nucleus for secondary recrystallization, and then repeatedly subjecting the steel plate to strain introduction and annealing treatment, the magnetic properties were significantly improved.

Moreover, with the above method, there is no need to provide a temperature gradient at the boundary between the secondary recrystallized area and the primary recrystallized area, and the secondary grain boundaries can be controlled and moved by utilizing strain even during short-time annealing. There is also the advantage that continuous finishing annealing can be used.

Such preferential growth of recrystallized grains by introducing strain and annealing has been applied in the past when creating single crystals (for example, C, G, Dunn and G, C.

Nonken Metal Prog, 64 (1
953) 71-75), but the present invention is completely different from the above-mentioned method of correcting the orientation of naturally occurring secondary grains by deformation to form desired nuclei. The nucleus is artificially and stably formed by welding, and the growth of the nucleus is progressed by repeatedly carrying out strain introduction and annealing.
JP-A-58-100627 and JP-A-59-215
419 publications, U, S, Patentk443791
By using naturally occurring secondary recrystallized grains as shown in No. 0 as nuclei, the nuclei are grown by temperature gradient annealing. .

The method of obtaining values is completely different, and the feature is that various controls can be controlled artificially.

As is clear from the above experimental results, extremely high B,
. In order to obtain this value, it is necessary to: ■ Weld a strip material with secondary grains whose (00i) axis is sharply controlled in the rolling direction to a steel plate; ■ Repeatedly apply strain introduction and annealing to the steel plate. It has been found that this method is extremely effective, and that by satisfying these conditions, it is possible to develop secondary recrystallized grains that are highly concentrated in the Goss orientation.

Next, the inventors conducted the following experiment.

After removing the non-metallic substances on the surface of the C material product board by pickling, it was mirror-polished to a center line average roughness Ra of 0.1 μm or less by electric field polishing. Thereafter, a 1 μ-thick TiN film was formed on the mirror-finished surface using an ion blating device (IcD method). Here, the ion blating conditions are acceleration voltage: 50 V, acceleration current: 500 A, and vacuum degree near x 10-' Torr.

The magnetic properties of the product plate thus obtained are B. -1,9
80(T), 1,7. . ~0.56 (corrected kg), which was extremely good.

From the above experimental results, in order to further improve the magnetic properties, it is necessary to
001) In addition to welding a strip-like material whose axis resembles secondary grains controlled sharply in the rolling direction, and then repeatedly subjecting the steel plate to strain introduction and annealing, the steel plate surface is further It was discovered that it is extremely effective to mirror-polish the steel plate and then form an ultra-thin film that can apply tension to the steel plate.

Next, this invention method will be specifically explained in order of manufacturing steps.

First, regarding the starting material of this invention, the components of conventionally known unidirectional electrical steel sheets, for example, C: 0.002 to 1.0
%, Si: 0.1-7.0% and Mn: 0
．． In addition to containing 002 to 0.15χ, as inhibitor forming components, s: o, oos to o, os%, S
e: 0.005-0.05%.

Te: 0.003-0.03%, Sb: 0.
005~0.05%, old 0.005~0.05%,
Sn: 0.01-0.5%, Cu: 0.01
~0.3%, Mo: 0.005~0.05%,
B: 0.0003-0.0040%, N: 0
．． 001-0.01%, Af: 0.005-0.
05%, Ti': 0.001-0.05%,
V: 0.001-0.05% and Nb: 0.
Any material containing at least one selected from 0.001 to 0.05% is advantageously suitable.

These materials are manufactured by conventional steel manufacturing methods such as converter furnaces and electric furnaces, and then made into slabs, sheet bars, or directly into thin steel sheets by the ingot-blooming method, continuous casting method, or roll quenching method. , hot rolling, warm rolling or cold rolling as necessary to obtain a silicon-containing steel plate. Then, if necessary, uniform annealing and further rolling including intermediate annealing are performed one or more times to achieve the final plate thickness. The purpose of these homogenizing annealing and intermediate annealing is recrystallization treatment to homogenize the crystal structure after rolling, and is usually performed at 800 to 1200°C for 3
Hold for 0 seconds to 10 minutes. Also, the finishing thickness is 0.50
am or less, but 0, 23, which makes secondary recrystallization unstable.
This invention is particularly effective for finishing thicknesses of 1 m or less.

Next, annealing is performed in wet hydrogen at 700 to 900°C for 1 to 15 minutes to remove C in the steel, and to develop secondary recrystallized grains with Goss orientation during the next annealing. Next, a recrystallized texture is formed.

After that, secondary recrystallization annealing is performed at 800-1000°C for 11-50 hours, and then at 1100-1250°C for 5-2 hours.
A final finish annealing consisting of a purification annealing for about 5 hours is performed, but in this invention, before the final annealing, a similar material with directionality is applied to the edge of the steel plate.
1) Welding under the condition that the axis is within 10 degrees to the rolling direction of the steel plate, and subsequently or thereafter, welding the weld and the non-secondary recrystallized area of the base steel plate from the weld to the inside of the base steel plate. In order to achieve this, a step is incorporated in which secondary recrystallized grains are grown step by step by repeating strain introduction and annealing step by step.

First, regarding welding of the same type of material which is to become the nucleus of the secondary recrystallized grains, the welding time is before the final annealing as described above. Furthermore, any conventional welding method such as gas, current, laser, plasma, electron beam, or ultrasonic waves can be used, and any of the welding methods, such as butt and overlapping, are suitable.

However, in such welding, it is important to control so that the (001) axis of the similar materials to be welded is within 10 degrees with respect to the rolling direction of the steel plate. That is, the corresponding (001
) If the axis deviates by more than 10° from the rolling direction of the steel plate, 81
This is because the disadvantage of iron loss deterioration occurs as the ° value decreases. Further, the similar material to be welded may be either single crystal or polycrystal, and may have any shape such as a plate shape or a linear shape.

Next, the amount of strain introduced into the steel plate is preferably about 0.1 to 30%. This is because if the amount of introduced strain is less than 0.1%, there will be insufficient dislocation density to act as a driving force for grain boundary movement, making recrystallized grain growth difficult in subsequent annealing. This is because the recrystallized grains become coarse, as disclosed in Japanese Patent No. 59-215419, and improvement in iron loss cannot be expected. On the other hand, if it exceeds 30%, randomly oriented recrystallized grains will occur in the matrix in front of the advancing recrystallized grains, the dislocation density that should be the driving force will decrease, and the preferential growth of Goss-oriented grains will become difficult. It is from.

Regarding strain introduction methods, methods include roll rolling, mechanical methods by projecting materials such as sand, and methods by impact or rapid heating and cooling effects caused by irradiation with energy beams such as lasers, electron beams, and plasma jets. Any method is fine.

Although there is no particular restriction on the area where strain is introduced, it is preferable that the weld zone where secondary recrystallized grains are likely to occur on the other side be narrow in the width direction of the steel plate, and conversely be wide in the steel plate area where secondary recrystallized grains are less likely to occur. .

The annealing area may be only the strain introduced area, a part of the strain introduced area, or the entire area including the strain introduced area and the non-strain introduced area.In short, the annealing area can be annealed sequentially from the edge of the steel plate in the width direction. It is sufficient to proceed with secondary recrystallization.

Next, the secondary recrystallization temperature is related to the amount of strain introduced, the crystal grain size, and the inhibitor strength; if the amount of strain is large, the crystal grain size is small, and the inhibitor effect is weak, a relatively low temperature may be used. When the amount of strain is small, the crystal grains are large, and the inhibitor effect is strong, it is preferable to use a higher temperature. Conventionally, 800 to 1000'C was considered suitable, but in this invention, the temperature is about 650 to 1000°C. Select an appropriate value after considering the strain introduction width within the temperature range.

In the present invention, it is not necessary to perform inclined annealing in the secondary recrystallization annealing described above, but from the viewpoint of further improvement of magnetic properties, it is necessary to It is advantageous to perform inclined annealing while applying a temperature gradient of about 1°C/cm or more.

By performing such a series of treatments, magnetic properties can be effectively improved. After removing non-metallic substances from the surface of the steel sheet, it is rolled with a smooth roll with a surface roughness of Ra51 μm, and then a non-oxidizing By performing purification annealing in an atmosphere, the steel plate can be flattened, its surface smoothed and cleaned, and the magnetic properties can be further improved.

Furthermore, in the present invention, it is possible to further improve the magnetic properties by coating the surface of the steel sheet with a tension-applying ultra-thin coating after final annealing.

In order to form such an ultra-thin film, first remove non-metallic substances from the surface of the steel sheet after purification annealing, and then apply chemical polishing or electric field polishing to reduce the smoothness of the steel sheet surface to a centerline average roughness Ra of 0. The diameter shall be 4 μm or less. This is because if the roughness is greater than this, no improvement in iron loss can be expected, even by applying an extremely thin film.

Next, Ti, Nb, Si, V, Cr, A are formed by dry plating such as CVD method or PVD method (ion blating or ion implantation).
f.

Mn, B, Ni, Co, l'lo, Zr,
Nitride and/or carbide of Ta, Hf, W and Aj! l Si, Mn+ Mg1Zn, T
An ultra-thin film consisting mainly of at least one selected from the oxides of i is firmly formed on the surface of the steel sheet.

In addition to the material of the coating, there are
Any material may be used as long as it has a low coefficient of thermal expansion and firmly adheres to the steel plate.

Furthermore, if necessary, the magnetic properties can be improved by applying a tension-applied low thermal expansion overcoat insulating film or performing magnetic domain refining treatment by laser irradiation or the like, according to a conventional method.

(Function) According to the present invention, a homogeneous material whose (001) axis is oriented in the rolling direction of the steel plate is welded to the edge of the steel plate as a seed crystal for recrystallization, and a suitable material is welded to the edge of the steel plate as a seed crystal for recrystallization. By repeatedly applying strain and annealing, the welded seed crystals continue to grow in the width direction of the steel sheet during the incubation period before new recrystallized grains with misoriented orientations occur and grow. It is thought that extremely good magnetic properties can be obtained because only the oriented grains of the seed crystal whose orientation has been strictly controlled recrystallize over the entire steel sheet.

Note that in the actual product, the welded portion may be left as is or may be cut and removed as necessary.

(Example) Example I C: 0.035%, Si: 3.25%, Mn
A silicon steel plate slab containing S: 0.035% and S: 0.015%, with the remainder consisting of Fe and unavoidable impurities, was hot rolled to a thickness of 2.3+nm and a width of 300 ttrm. After making it into a board, heat it at 900°C.
After homogenization annealing for 1 minute and then cold rolling for the first time to give an intermediate thickness of 0.36+++1+, 950
The steel plate surface was degreased and annealed at 820°C in wet hydrogen for 3 minutes. After decarburization and primary recrystallization annealing for 10 minutes, a Goss-oriented single crystal plate whose (001) axis is deviated by 2° from the rolling direction is placed on both edges of the steel plate so that the rolling direction and the rolling surface coincide. Then, the welded part was subjected to a combination treatment of strain introduction by laser and plasma jet and annealing three times, and then the boundary between the single crystal and the primary recrystallized part was removed by rolling. 5InIll towards the primary recrystallization part
Introducing strain with a deformation amount of 1% with a width of
Oxides on the surface were removed by pickling.

After that, after rolling with a reduction rate of 1%, 120
Purification annealing was performed at 0°C for 5 hours.

The magnetic properties of the thus obtained product are Bto=1.982
(T).

Example 2 The product plate obtained in Example 1 was polished to a mirror finish with a center line average roughness Ra of 0.1 μm or less, and then polished to a mirror finish surface of a steel plate maintained at 400°C. A TiN film with a thickness of 1 μm was formed by ion blasting.

The magnetic properties of the product plate thus obtained are B1°=1.980.
(T), W1715°=0.53 W/kg.

A single crystal plate whose orientation is controlled in this way is welded to a steel plate.
A product with high magnetic flux density can be obtained by forming the next grain nucleus and then repeating strain introduction and annealing to grow this nucleus in stages.The steel plate surface is also smoothed and a tension-applying coating is applied to the steel plate surface. By coating the steel, it was possible to obtain an extremely low iron loss value.

Example 3 C: 0.030%, Si: 3.30%, Mn
: 0.030%, S: 0.015%, Affi
: 0.015% and N : 0.0070%, with the remainder being Fe and unavoidable impurities. Hot rolled to a silicon steel slab with a thickness of 2.3 mm and a width of 30 mm.
After forming a hot-rolled sheet with a thickness of 0 mm, it was homogenized annealed at 900°C for 13 minutes, and then cold-rolled for the first time to a thickness of 0.5 mm.
After reducing the thickness to 0 mm, intermediate annealing was performed at 1.1000°C for 13 minutes, and then a second cold rolling was performed to obtain a plate thickness of 0.23 mm.
It was finished into a cold-rolled sheet of mm. Next, the steel plate surface is degreased and (0
01) A Goss-oriented single crystal plate whose axis was deviated by 2° from the rolling direction was butt-welded to both edges of the steel plate using a laser so that the rolling direction and the rolling surface coincided with each other. Next, decarburization and primary recrystallization annealing were performed at 820°C for 3 minutes in wet hydrogen, and then a strain of 2% was uniformly introduced into the steel plate by rolling. Next, the welded part is subjected to a combination treatment of strain introduction using a laser and plasma jet and annealing five times, and the single crystal is grown two times toward the steel plate part, that is, the primary recrystallized part. , from the boundary between the single crystal and the primary recrystallization area to the primary recrystallization area in steps of 10 mm width.
After repeating the io bone annealing at 0°C 15 times to grow the orientation of the single crystal over the entire steel plate,
Purification annealing was performed at 200'C for 5 hours.

When the magnetic flux density of the product plate thus obtained was measured,
Boo = 1.975 (T).

Example 4 The product board obtained in Example 3 was subjected to the same surface treatment as in Example 2 to form an ultra-thin TiN film with a thickness of 1 μm.

(The magnetic properties of the product obtained are B1゜=1.98
0 (T), W+tzso=0.54 (w/kg)
Met.

(Effects of the Invention) Thus, according to the present invention, after welding similar materials with controlled crystal orientation, by repeatedly performing strain introduction and annealing, secondary recrystallized grains are grown step by step and accumulated in hardness. It is possible to rationally form a secondary recrystallized structure consisting of Goss-oriented grains, and furthermore, by smoothing the steel plate surface, applying tension-applying ultra-thin coatings, and effectively utilizing magnetic domain refining technology, the magnetic properties are significantly superior. It is also possible to easily obtain grain-oriented electrical steel sheets by continuous annealing, which greatly contributes to energy saving.

[Brief explanation of the drawing]

FIG. 1 is a graph comparing the relationship between annealing temperature and time on the onset of secondary recrystallization between a strained steel plate and a steel plate without strain.

Claims (1)

[Claims] 1. A silicon-containing steel slab is hot-rolled, then cold-rolled once or twice or more with intermediate annealing in between, and then subjected to decarburization and primary recrystallization annealing. , Then, in manufacturing a unidirectional electrical steel sheet through a series of steps in which final finish annealing is performed, a similar material with directionality is applied to the edge of the steel sheet before final finish annealing.
1] A process of welding under conditions such that the axis is within 10 degrees to the rolling direction of the steel plate, and subsequently or thereafter, welding the non-secondary recrystallized area in stages from the welded area toward the inside of the base steel plate. 1. A method for producing a grain-oriented electrical steel sheet with excellent magnetic properties, comprising the step of growing secondary recrystallized grains by repeating strain introduction and annealing multiple times. 2. A silicon-containing steel slab is hot-rolled, then cold-rolled once or twice or more with intermediate annealing in between, then subjected to decarburization and primary recrystallization annealing, and then final finish annealing. In manufacturing unidirectional electrical steel sheets through a series of processes, a similar material with directionality is applied to the edge of the steel sheet before final annealing.
1] A process of welding under conditions such that the axis is within 10 degrees to the rolling direction of the steel plate, and subsequently or thereafter, welding the non-secondary recrystallized area in stages from the welded area toward the inside of the base steel plate. It has a step of growing secondary recrystallized grains by repeating strain introduction and annealing multiple times, and after final annealing, oxides on the surface of the steel sheet are removed, and then polished to a center line average roughness Ra of 0. 4μ
After finishing to a mirror finish of m or less, on the mirror finish surface,
By dry plating, Ti, Nb, Si, V,
Cr, Al, Mn, B, Ni, Co, Mo, Zr, Ta
, Hf, W nitride and/or carbide and Al
, Si, Mn, Mg, Zr, and Ti oxides.