JP2022513169A - Directional electrical steel sheet and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grain-oriented electrical steel sheet having improved magnetism and a method for manufacturing the same by including a plurality of cold rolling and decarburization annealing steps. SOLUTION: The method for manufacturing a directional electromagnetic steel sheet according to the present invention is a step of heating a slab, a step of hot rolling a slab to manufacture a hot-rolled steel sheet, a step of hot-rolling a hot-rolled steel sheet, and a hot-rolling step. The stage of primary cold rolling of hot-rolled sheet that has been plate-baked, the stage of decarburizing and annealing the primary cold-rolled steel sheet, and the stage of secondary cold rolling of a steel sheet that has been decarburized and annealed. It is characterized by including a step of continuously annealing a steel sheet for which interrolling has been completed, and a step of batch annealing the continuously annealed steel sheet. [Selection diagram] Fig. 1

Description

The present invention relates to a grain-oriented electrical steel sheet and a method for producing the same, and more particularly to a grain-oriented electrical steel sheet having improved magnetism by including a plurality of cold rolling and decarburization annealing steps and a method for producing the same.

The grain-oriented electrical steel sheet is a soft magnetic material having excellent magnetic properties in the rolling direction and composed of crystal grains having a crystal orientation of {110} <001>, which is also known as a Goss orientation.
Such grain-oriented electrical steel sheets are rolled to the final thickness through hot rolling, hot rolling, and cold rolling after slab heating, and then high-temperature annealing for primary recrystallization annealing and secondary recrystallization formation. Manufactured via.
Usually, the secondary recrystallization annealing step of grain-oriented electrical steel sheets requires a low temperature rise rate and long-term purification annealing at a high temperature, so that it can be said to be a process that consumes a lot of energy. Since secondary recrystallization is formed through such an extreme process to produce a grain-oriented electrical steel sheet having excellent magnetic properties, the following process difficulties occur.

First, since the same heat treatment pattern cannot be applied to each part due to a temperature deviation between the outer winding part and the inner winding part due to the heat treatment in the coil state, the outer winding part and the inner winding part Magnetic anomaly occurs. Secondly, after decarburization annealing, MgO is coated on the surface, and various surface defects occur in the process of forming a base coating during high temperature annealing, which lowers the actual yield. Thirdly, the decarburized plate that has been decarburized and annealed is wound in a coil form, then annealed at a high temperature, then flattened and annealed again, and then an insulating coating is applied. There is a problem of doing.
In order to overcome such process restrictions, a technique has been proposed in which normal crystal growth is utilized without utilizing the secondary recrystallization phenomenon by adjusting the decarburization annealing and the cold reduction rate. However, in continuous annealing, there is a limit to the crystal grain growth of the final crystal grains due to the short heat treatment time of water content, and it is not possible to grow as crystal grains having an optimum particle size, and there is a limit to the improvement of iron loss.

An object of the present invention is to provide a grain-oriented electrical steel sheet having improved magnetism and a method for manufacturing the same by including a plurality of cold rolling and decarburization annealing steps.

The method for producing a directional electromagnetic steel plate according to the present invention includes a stage of heating a slab, a stage of hot rolling the slab to produce a hot-rolled steel plate, a stage of hot-rolling a hot-rolled steel plate, and a stage of hot-rolling a hot-rolled plate. The stage of primary cold rolling of a hot-rolled steel sheet, the stage of decarburizing and annealing a primary cold-rolled steel sheet, the stage of secondary cold rolling of a steel sheet that has been decarburized and tempered, and the stage of secondary cold rolling are completed. It is characterized by including a step of continuously rolling the rolled steel sheet and a step of batch rolling the continuously rolled-rolled steel sheet.

The slab contains, by weight, Si: 1.0% to 4.0%, C: 0.1% to 0.4%, with the balance consisting of Fe and unavoidable impurities.
It is intended to further contain Mn: 0.1% by weight or less and S: 0.005% by weight or less.

At the stage of hot rolling and annealing the slab, including the decarburization process,
In the stage of annealing the hot-rolled sheet, the sheet is annealed at a temperature of 850 ° C to 1000 ° C and a dew point temperature of 50 ° C to 70 ° C.
The stage of decarburizing and annealing a primary cold-rolled steel sheet is characterized by annealing at a temperature of 850 ° C to 1000 ° C and a dew point temperature of 50 ° C to 70 ° C.

The step of decarburizing and annealing the primary cold-rolled steel sheet is to anneaate in the austenite single-phase region or the region where the ferrite and austenite composite phase is present.
After the stage of decarburizing and annealing the primary cold-rolled steel sheet, the average diameter of the crystal grains became 150 to 250 μm.
The step of decarburizing and annealing the primary cold-rolled steel sheet and the step of secondary cold-rolling the steel sheet for which the decarburization and annealing has been completed are repeated two or more times.

In the continuous annealing step, annealing is performed at a temperature of 850 ° C to 1000 ° C and a dew point temperature of 50 ° C to 70 ° C for 1 to 5 minutes.
The batch annealing step is to anneal at a temperature of 1000 ° C to 1200 ° C and a dew point temperature of -20 ° C or lower for 1 to 8 hours.
After the batch annealing step, the volume fraction of the crystal grains forming an angle of 15 ° or less from {110} <001> is 40% or more.
It is characterized in that the area fraction of the crystal grains having a diameter of 1000 μm to 5000 μm in the whole crystal grains is 20 to 70%.

The grain-oriented electrical steel sheet according to the present invention is characterized in that the area fraction of the crystal grains having a diameter of 1000 μm to 5000 μm in the whole crystal grains is 20 to 70%.

The electrical steel sheet contains Si: 1.0% to 4.0%, C: 0.005% or less (excluding 0%) in weight%, and the balance consists of Fe and unavoidable impurities.
Mn: 0.1% by weight or less and S: 0.005% by weight or less are further contained.
The volume fraction of the crystal grains forming an angle of 15 ° or less from {110} <001> is 40% or more.
The ratio (D2 / D1) of the diameter of the circumscribed circle (D1) to the diameter of the inscribed circle (D2) is 0.5 or more. And.

The grain-oriented electrical steel sheet according to the present invention has excellent magnetic properties by stably forming goth crystal grains having a large diameter while utilizing normal crystal growth.
Further, since AlN and MnS are not used as the crystal grain growth inhibitor, it is not necessary to heat the slab at a high temperature of 1300 ° C. or higher.
Further, it is not necessary to remove N and S which are precipitates, and the purification annealing time can be relatively short, so that the productivity can be improved.
Further, it is possible to provide a grain-oriented electrical steel sheet having magnetic properties cracked in the width direction.

It is a photograph which observed the surface of the grain-oriented electrical steel sheet manufactured by the invention material 2 with a scanning electron microscope. It is a photograph which observed the surface of the grain-oriented electrical steel sheet manufactured by the comparative material 2 with a scanning electron microscope.

Terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and / or sections. These terms are used only to distinguish one part, component, area, layer or section from another part, component, area, layer or section. Therefore, the first part, component, region, layer or section described below may be referred to as the second part, component, region, layer or section without departing from the scope of the present invention.
The terminology used herein is merely to refer to a particular embodiment and is not intended to limit the invention. The singular form used herein also includes multiple forms unless the wording has a clear opposite meaning. As used herein, the meaning of "contains" embodies a particular property, region, integer, stage, behavior, element and / or component and other properties, region, integer, stage, behavior, element and / or. It does not exclude the presence or addition of ingredients.
When referring to one part being "above" another part, it may be "directly above" the other part, or another part may be mediated in between. In contrast, when one mentions that one part is "directly above" another, no other part is intervened in the meantime.
Although not defined differently, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by a person of ordinary knowledge in the art to which the invention belongs. Have. Terms defined in commonly used dictionaries are additionally interpreted as having a meaning consistent with the relevant technical literature and currently disclosed content, and are not interpreted in an ideal or very formal sense unless defined.
Further, unless otherwise specified,% means% by weight, and 1 ppm is 0.0001% by weight.
The meaning of further containing an additional element in one embodiment of the present invention means that iron (Fe), which is the balance, is contained in place of the additional amount of the additional element.

Hereinafter, embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention belongs can easily carry out the embodiments. However, the present invention can be realized in a variety of different forms and is not limited to the embodiments described herein.
The method for producing a directional electromagnetic steel plate according to the present invention includes a stage of heating a slab, a stage of hot rolling the slab to produce a hot-rolled steel plate, a stage of hot-rolling a hot-rolled steel plate, and a stage of hot-rolling a hot-rolled plate. The stage of primary cold rolling of a hot-rolled steel sheet, the stage of decarburizing and annealing a primary cold-rolled steel sheet, the stage of secondary cold rolling of a steel sheet that has been decarburized and tempered, and the stage of secondary cold rolling are completed. It includes a step of continuously rolling a rolled steel sheet and a step of batch rolling a continuously rolled steel sheet.

Hereinafter, each step will be specifically described.
First, heat the slab.
The slab contains Si: 1.0% to 4.0%, C: 0.1% to 0.4% by weight, and the balance consists of Fe and unavoidable impurities.
The reasons for limiting the composition are as follows.
Silicon (Si) lowers the magnetic anisotropy of electrical steel sheets, increases resistivity, and improves iron loss. When the Si content is less than 1.0% by weight, the iron loss becomes inferior, and when it exceeds 4.0% by weight, the brittleness increases. Therefore, the Si content in grain-oriented electrical steel sheets after the slab and final annealing steps can be 1.0-4.0% by weight. More specifically, the Si content is 1.5 to 3.5% by weight.

Carbon (C) in the slab requires a process in which C in the central part escapes to the surface layer in order for the Goss crystal grains in the surface layer to diffuse to the central part during the intermediate decarburization annealing and the final decarburization annealing. The content of C is 0.1 to 0.4% by weight. More specifically, the content of C in the slab is 0.15 to 0.3% by weight. Further, after the final annealing step in which decarburization is completed, the carbon content in the final grain-oriented electrical steel sheet is 0.0050% by weight or less, and more specifically, 0.002% by weight or less.
The slab further contains Mn: 0.1% by weight or less and S: 0.005% by weight or less.

Mn and S form MnS precipitates and interfere with the growth of Goss crystal grains that diffuse to the center during the decarburization process. Therefore, it is preferable that Mn and S are not added. However, in consideration of the amount inevitably mixed in during the steelmaking process, Mn and S in the grain-oriented electrical steel sheet after the slab and the final annealing step are Mn: 0.1% by weight or less and S: 0.005% by weight. It is controlled as follows.
The balance consists of Fe and unavoidable impurities. The unavoidable impurities are impurities mixed in the steelmaking stage and the manufacturing process of the grain-oriented electrical steel sheet, and since they are widely known in the art, specific description thereof will be omitted. Specifically, components such as Al, N, Ti, Mg, and Ca react with oxygen in steel to form oxides, and it is necessary to strongly suppress them. It can be controlled at 0.005% by weight or less. In one embodiment of the present invention, the addition of elements other than the alloy components described above is not excluded, but various elements are included within a range that does not impair the technical idea of the present invention. When an additional element is further contained, the remaining Fe is contained in place of Fe.

More specifically, the slab contains, by weight, Si: 1.0% to 4.0%, C: 0.1% to 0.4%, and the balance consists of Fe and unavoidable impurities.
The slab heating temperature is 1100 ° C to 1350 ° C, which is higher than the normal heating temperature. If the temperature is high when the slab is heated, there is a problem that the hot-rolled structure becomes coarse and adversely affects the magnetism. However, in the method for manufacturing grain-oriented electrical steel sheets according to the present invention, since the carbon content of the slab is relatively high, the hot-rolled structure does not become coarse even if the slab reheating temperature is high, and the temperature is higher than usual. Reheating is even more advantageous during hot rolling.

Next, the slab is hot-rolled to produce a hot-rolled steel sheet.
Hot rolling is manufactured as a hot rolled plate with a thickness of 1.5 to 4.0 mm by hot rolling so that an appropriate rolling ratio can be applied at the final cold rolling stage to produce the final product thickness.
The hot rolling temperature and the cooling temperature are not particularly limited, but as an example of excellent magnetism, the hot rolling end temperature is set to 950 ° C. or lower, and the cooling is rapidly cooled with water and wound up at 600 ° C. or lower.
Next, the hot-rolled steel sheet is annealed. At this time, the hot-rolled sheet annealing involves a decarburization process. Specifically, the hot-rolled sheet is annealed at a temperature of 850 ° C to 1000 ° C and a dew point temperature of 50 ° C to 70 ° C. After the above-mentioned annealing, additional annealing is performed at a temperature of 1000 to 1200 ° C. and a dew point temperature of 0 ° C. or lower. After performing hot-rolled sheet annealing, pickling is performed.

Next, primary cold rolling is carried out to manufacture a cold-rolled steel sheet.
In the normal manufacturing process of grain-oriented electrical steel sheets, it is effective to carry out cold rolling once at a high pressure reduction rate close to 90%. This is because only the Goss crystal grains in the primary recrystallized grains create an advantageous environment for grain growth. However, the method for producing a directional electromagnetic steel sheet according to the present invention does not utilize the abnormal grain growth of the Goss directional crystal grains, and internally diffuses the Goss crystal grains of the surface layer portion generated by decarburization annealing and cold rolling. Therefore, it is advantageous to form a large number of Goss-oriented crystal grains in the surface layer portion.
Therefore, when cold rolling is carried out at a rolling reduction of 50% to 70% during cold rolling, a large number of Goss textures are formed on the surface layer portion. More specifically, it is 55% to 65%.
Next, the cold-rolled steel sheet is decarburized and annealed. At this time, the decarburization annealing step is carried out in the austenite single-phase region or the region in which the ferrite and austenite composite phase is present. Specifically, it is annealed at a temperature of 850 ° C to 1000 ° C and a dew point temperature of 50 ° C to 70 ° C. The atmosphere is a mixed gas atmosphere of hydrogen and nitrogen. Further, the amount of decarburized during annealing is 0.0300% by weight to 0.0600% by weight. After the above-mentioned annealing, additional annealing is performed at a temperature of 1000 to 1200 ° C. and a dew point temperature of 0 ° C. or lower.
In such a decarburization annealing process, the size of the crystal grains on the surface of the electrical steel sheet grows coarsely, but the crystal grains inside the electrical steel sheet remain as a fine structure. After such decarburization annealing, the average diameter of the crystal grains is 150 μm to 250 μm. At this time, the crystal grains are surface ferrite crystal grains. Further, the diameter of the crystal grain means the diameter of the circle assuming a virtual circle having the same area as the crystal grain.

Next, the steel sheet that has been decarburized and annealed is secondarily cold-rolled. Since the secondary cold rolling is the same as the primary cold rolling, a specific description thereof will be omitted.
The steps of decarburizing and annealing the cold-rolled steel sheet and the secondary cold rolling of the steel sheet that has been decarburized and annealed can be repeated two or more times. By repeating the process two or more times, a large number of Goss textures are formed on the surface layer.
Next, the steel sheet for which the secondary cold rolling has been completed is continuously annealed.
The step of continuous annealing is annealing at a temperature of 850 ° C to 1000 ° C and a dew point temperature of 50 ° C to 70 ° C. The cold-rolled plate before continuous annealing is in a state where 40% to 60% of the carbon content remains with respect to the carbon weight of the slab after decarburization annealing. Therefore, in the stage of continuous annealing, the crystal grains formed on the surface layer portion diffuse into the inside while carbon escapes. At the stage of continuous annealing, decarburization can be carried out so that the amount of carbon in the steel sheet is 0.005% by weight or less.

In the stage of continuous annealing, annealing is performed for 1 to 5 minutes. The purpose of the continuous annealing step is to grow the crystal grains to a certain size or more after decarburizing the carbon in the steel. The reason is that the fraction of Goss crystal grains continuously increases through the process of decarburization and the grain growth immediately after that. This is because the Goss crystal grains grow while eating the surrounding Non-Goss crystal grains. However, it can be said that the crystal growth is restricted because the annealing time is limited to a few minutes in consideration of the productivity of continuous annealing. The present invention claims that it is effective in reducing iron loss by inducing crystal growth through additional batch annealing. At this time, the Goss fraction does not increase, but the iron loss decreases due to the effect of increasing the size of the crystal grains.
After the step of continuous annealing, an annealing separator is applied. Since the annealing separator is widely known in the art, a specific description thereof will be omitted. For example, an annealing separator containing MgO as a main component can be used.

Next, the continuously annealed steel sheet is batch annealed. Batch annealing means winding and annealing a steel sheet in a coil shape.
In the batch annealing step, an aggregate with a diffused Goth orientation grows in the continuous annealing step. In the method for producing grain-oriented electrical steel sheets according to the present invention, the Goth texture has a crystal grain diameter of 5 mm or less, unlike the case where crystal grains grow due to the conventional abnormal particle growth. Specifically, the grain fraction with a diameter of 1000 um to 5000 um increases. Therefore, there are many Goth crystal grains whose crystal grain size is smaller than that of the conventional grain-oriented electrical steel sheet manufactured by abnormal crystal growth, but the crystal grain size minimizes iron loss. Adjusted to the appropriate size so that it can be. More specifically, the surface integral of the crystal grains having a diameter of 1000 μm to 5000 μm in the whole crystal grains is 20 to 70%. At this time, the surface integral of the crystal grains was measured on a plane parallel to the rolled plane (ND plane) of the steel sheet. More specifically, the surface integral of the crystal grains having a diameter of 1000 μm to 5000 μm in the whole crystal grains is 20 to 60%. More specifically, the surface integral of the crystal grains having a diameter of 1000 μm to 5000 μm in the whole crystal grains is 20 to 50%.
The batch annealing step can be annealed at a temperature of 1000 ° C. to 1200 ° C. and a dew point temperature of −20 ° C. or lower.
The batch annealing is annealed for 1 to 8 hours. More specifically, it is annealed for 2 to 5 hours.
Further, in the method for manufacturing grain-oriented electrical steel sheets according to the present invention, the magnetism is improved because the goth fraction is high. Specifically, the volume fraction of the crystal grains forming an angle of 15 ° or less from {110} <001> is 40% or more, more specifically 40% to 75%, and more specifically 45 to 60%. ..

The grain-oriented electrical steel sheet according to the present invention has an area fraction of crystal grains having a diameter of 1000 μm to 5000 μm in the whole crystal grains of 20 to 70%.
Since the area distribution of crystal grains has been described in detail in relation to the method for manufacturing grain-oriented electrical steel sheets, overlapping description will be omitted.
The electrical steel sheet contains Si: 1.0% to 4.0% and C: 0.005% or less (excluding 0%) in weight%, and the balance consists of Fe and unavoidable impurities.
The magnetic steel sheet further contains Mn: 0.1% by weight or less and S: 0.005% by weight or less.
Except for C, it is the same as the content of the slab component limitation, so duplicate description will be omitted.
The volume fraction of the crystal grains forming an angle of 15 ° or less from {110} <001> is 40% or more.
The ratio (D2 / D1) of the diameter of the circumscribed circle (D1) to the diameter of the inscribed circle (D2) is 0.5 or more, and the goth crystal grains are 95 area% or more of the total goth crystal grains. The above-mentioned form of crystal grains is formed by the manufacturing process peculiar to the present invention.

The grain-oriented electrical steel sheet according to the present invention has a high goth fraction, so that the magnetism is improved. Specifically, the iron loss (W _17/50 ) is 1.3 W / kg or less, more specifically, the iron loss (W _17/50 ) is 1 to 1.3 W / kg, and more specifically 1. It is 1 to 1.25 W / kg. Iron loss W _17/50 is the magnitude of iron loss (W / kg) induced under 1.7 Tesla and 50 Hz conditions.
Hereinafter, specific examples of the present invention will be described. However, the following examples are merely specific examples of the present invention, and the present invention is not limited to the following examples.

Example 1
A slab containing, by weight%, Si: 2.32%, C: 0.195%, with the balance consisting of Fe and unavoidable impurities, was heated at a temperature of 1250 ° C. and then hot rolled, followed by an annealing temperature of 950. The hot-rolled plate was annealed at ° C. and a dew point temperature of 60 ° C. Then, after cooling the steel sheet, it was pickled and cold-rolled at a reduction rate of 65% to produce a cold-rolled sheet having a thickness of 0.8 mm.
The cold-rolled plate is again cold-rolled at a reduction rate of 65% after being decarburized and annealed for 80 seconds in a wet mixed gas atmosphere of hydrogen and nitrogen (dew point temperature 60 ° C.) at a temperature of 950 ° C. to a thickness. A 0.28 mm cold rolled plate was manufactured.
Then, at the time of final annealing, decarburization annealing was carried out for 2 minutes in a wet mixed gas atmosphere of hydrogen and nitrogen (dew point temperature 60 ° C.) at a temperature of 950 ° C., and then continuously hydrogen and nitrogen at 1100 ° C. as shown in Table 1. The heat treatment was carried out in the mixed gas atmosphere (dew point temperature 60 ° C.) of the above, or in the coiled state, the heat treatment was carried out in the mixed gas atmosphere of hydrogen and nitrogen at 1200 ° C. during the time shown in Table 1 below.
Table 1 is a table showing the Goss fraction of the crystal grains of the grain-oriented electrical steel sheet after high-temperature annealing according to the examples, the area fraction of the crystal grains of 1 mm or more and 5 mm or less, and the iron loss. For the Goss fraction, the volume fraction of the crystal grains forming an angle of 15 ° or less from {110} <001> was measured. After surface cleaning of the finally obtained steel sheet, iron loss was measured under 1.7 Tesla and 50 Hz conditions using a single plate magnetic measurement method.

表１に示すように、バッチ焼鈍を適切な時間の間に行った発明材１～発明材４は、直径が１～５ｍｍである結晶粒の面積分率が高いことを確認できる。ゴス分率が比較材に比べて比較的低くても鉄損がむしろ優れていることを確認できる。
図１および図２では、発明材２および比較材２で製造した方向性電磁鋼板の表面を走査電子顕微鏡で観察した写真を示す。
図１および図２で確認できるように、発明材２で製造した方向性電磁鋼板の結晶粒が比較的大きく形成されたことを確認できる。

As shown in Table 1, it can be confirmed that the invention materials 1 to 4, which have been subjected to batch annealing for an appropriate time, have a high area fraction of crystal grains having a diameter of 1 to 5 mm. It can be confirmed that the iron loss is rather excellent even if the Goth fraction is relatively low compared to the comparative material.
1 and 2 show photographs of the surfaces of grain-oriented electrical steel sheets manufactured with the invention material 2 and the comparative material 2 observed with a scanning electron microscope.
As can be confirmed in FIGS. 1 and 2, it can be confirmed that the crystal grains of the grain-oriented electrical steel sheet manufactured from the invention material 2 are formed relatively large.

The present invention is not limited to the above-described embodiments and / or examples, and can be manufactured in various forms different from each other. You should be able to understand that it can be implemented in other concrete forms without changing the specific ideas and essential features. Therefore, it should be understood that the embodiments and / or examples described above are exemplary in all respects and are not limiting.

Claims (14)

By weight%, Si: 1.0% to 4.0%, C: 0.005% or less (excluding 0%), Mn: 0.1% by weight or less (excluding 0%), S: 0 It contains .005% by weight or less (excluding 0%), and the balance consists of Fe and unavoidable impurities.
A grain-oriented electrical steel sheet having a diameter of 1000 μm to 5000 μm in the whole crystal grain and an area fraction of the crystal grain of 20 to 70%. The grain-oriented electrical steel sheet according to claim 1, wherein the volume fraction of the crystal grains forming an angle of 15 ° or less from {110} <001> is 40% or more. The ratio (D2 / D1) of the diameter of the circumscribed circle (D1) to the diameter of the inscribed circle (D2) is 0.5 or more. The directional electromagnetic steel plate according to claim 1. The stage of heating the slab,
At the stage of hot rolling the slab to produce a hot-rolled steel sheet,
The stage of annealing the hot-rolled steel sheet,
The stage of primary cold rolling of the hot-rolled steel sheet that has been annealed.
The stage of decarburizing and annealing the primary cold-rolled steel sheet,
The stage of secondary cold rolling of the steel sheet for which decarburization annealing has been completed,
A method for producing a grain-oriented electrical steel sheet, which comprises a step of continuously annealing a steel sheet for which secondary cold rolling has been completed, and a step of batch annealing a steel sheet that has been continuously annealed. The method for manufacturing a grain-oriented electrical steel sheet according to claim 4, wherein the step of annealing the hot-rolled sheet includes a decarburization step. The method for manufacturing a grain-oriented electrical steel sheet according to claim 4, wherein the step of annealing the hot-rolled sheet is annealing at a temperature of 850 ° C to 1000 ° C and a dew point temperature of 50 ° C to 70 ° C. The grain-oriented electrical steel sheet according to claim 4, wherein the step of decarburizing and annealing the primary cold-rolled steel sheet is annealed at a temperature of 850 ° C to 1000 ° C and a dew point temperature of 50 ° C to 70 ° C. Manufacturing method. The grain-oriented electrical steel sheet according to claim 4, wherein the step of decarburizing and annealing the primary cold-rolled steel sheet is annealed in a region where an austenite single phase region or a composite phase of ferrite and austenite is present. Manufacturing method. The method for producing grain-oriented electrical steel sheets according to claim 4, wherein after the step of decarburizing and annealing the primary cold-rolled steel sheet, the average diameter of crystal grains is 150 to 250 μm. The fourth aspect of claim 4, wherein the step of decarburizing and annealing the primary cold-rolled steel sheet and the step of secondary cold-rolling the steel sheet for which the decarburization annealing is completed are repeated two or more times. Manufacturing method of directional electromagnetic steel sheet. The method for manufacturing a grain-oriented electrical steel sheet according to claim 4, wherein the step of continuous annealing is annealing at a temperature of 850 ° C to 1000 ° C and a dew point temperature of 50 ° C to 70 ° C. The method for manufacturing a grain-oriented electrical steel sheet according to claim 4, wherein the step of continuous annealing is annealing for 1 to 5 minutes. The method for manufacturing a grain-oriented electrical steel sheet according to claim 4, wherein the batch annealing step is annealed at a temperature of 1000 ° C. to 1200 ° C. and a dew point temperature of −20 ° C. or lower. The method for manufacturing a grain-oriented electrical steel sheet according to claim 4, wherein the batch annealing step is annealed for 1 to 8 hours.

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