WO2019132378A1

WO2019132378A1 - Oriented electrical steel sheet and method for manufacturing same

Info

Publication number: WO2019132378A1
Application number: PCT/KR2018/016139
Authority: WO
Inventors: 주형돈; 고경준; 이상우; 서진욱
Original assignee: 주식회사 포스코
Priority date: 2017-12-26
Filing date: 2018-12-18
Publication date: 2019-07-04
Also published as: KR20190077986A; KR102106998B1

Abstract

Introduced is an oriented electrical steel sheet, comprising, in percentage by weight, 2.0 to 7.0% of Si; 0.005% or less of C (excluding 0%); 0.001 to 0.05% of N; and 0.001 to 0.5% of In, at least one of 0.03 to 0.5% of Cu; 0.005 to 0.1% of Bi; 0.03 to 0.5% of V; 0.03 to 0.5% of Nb; 0.03 to 0.5% of Te; and 0.03 to 0.5% of Mo, the balance being Fe and unavoidable impurities.

Description

【Specification】

Title of the Invention

Directional electrical steel sheet and manufacturing method thereof

TECHNICAL FIELD

To a directional electric steel sheet and a manufacturing method thereof. Specifically, the present invention relates to a directional electrical steel sheet including a specular element and a method of manufacturing the same.

TECHNICAL BACKGROUND OF THE INVENTION

Improvement of surface physical property or method of imparting surface tension by chemical methods such as conventional surface treatment is a method of improving the magnetic properties of a material by positively improving the properties of the surface of the oriented electrical steel sheet. As a representative example thereof, there is a method for removing postustite (Mg ₂ SiO ₄₎ , that _is , a base coating layer, which is produced through a chemical reaction of an MgO slurry, which is an adhesion preventing agent for an oxide layer and a coil necessarily generated in decarburization annealing.

Techniques for removing the base coating layer include a method of forcibly removing a conventional product having a base coating layer formed thereon with sulfuric acid or hydrochloric acid, and a technique of removing or suppressing the base coating layer during its production, that is, glassless technology.

The main research direction of glassless technology to date is the technology to use surface etching effect in high temperature annealing process after addition of chloride to MgO which is annealing separator, and to apply A1 ₂₀₃ powder as annealing separator, And the technology that is not intended to be formed.

The ultimate direction of this technology is to eliminate the surface pinning site (Pinning Si te) that eventually leads to magnetic deterioration by intentionally preventing the base coating layer in the manufacture of electrical steel sheets, and ultimately to improve the magnetic properties of the oriented electrical steel sheet .

In both of the above-described glass-free processes, namely, the method of suppressing the formation of the forsterite layer and the technique of separating the base coating layer from the base material in the high-temperature annealing step, both the hydrogen and nitrogen gas and dew- There is a problem in the process that control is required. The reason for controlling the oxidizing ability to a low level is that the oxide layer formed on the surface of the base material at the time of decarburization is minimized 2019/132378 1 »(: 1 ^ {2018/016139

The oxide layer formed when the oxidation performance is low in the furnace is mostly silica (O ₂ ) oxide, which suppresses the formation of the iron-based oxide. Therefore, there is an advantage that the iron-calculated cargo is not left on the surface after the high temperature annealing. However, in such a case, it is difficult to ensure an adequate primary recrystallized grain size due to decarburization failure, and also a problem may occur in secondary recrystallization grain growth upon high-temperature annealing. Therefore, in order to thin the oxide layer while appropriately securing the de- The time must be longer than the reprocessing process, which reduces productivity.

In addition, the conventional method of controlling the oxidation ability to a minimum and forming the oxide layer to the minimum to suppress the formation of the base coat layer as much as possible has a different dew point and temperature behavior depending on the position of the plate in the coil in the case of high temperature annealing, At this time, there is a difference in the formation of the base coating layer, resulting in a difference in the degree of the glassyness, which may cause problems in the mass production due to the discrepancy in the plate portion.

DISCLOSURE OF THE INVENTION

[Problem to be solved]

According to an embodiment of the present invention, there is provided a directional electric steel sheet having a uniform mirror surface effect and an improved magnetic property by controlling the content of phosphorus element phosphorus and adjusting the content of the inhibitor auxiliary element.

MEANS FOR SOLVING THE PROBLEMS

The grain-oriented electrical steel sheet according to one embodiment of the present invention comprises: 2.0% to 7.0%, 0: 0.005% or less (excluding 0%), 0.001 to 0.05% and 1 0.001 to 0.5% 0 to ₁ : 0.03 to 0.5%, 0.005 to 0.1%, V: 0.03 to 0.5%, 0.03 to 0.5%, ₁₆ : 0.03 to 0.5% and 0.03 to 0.5%

And inevitable impurities.

V, Te, and ¾: 0.003 to 1.4%. 0.01 to 0.1%, 11 ₁₁ : 0.005 to 0.9% and 0.03% or less (excluding 0%).

0.005 to 0.15% and ¾: 0.005 to 0.2%. 2019/132378 1 »(: 1 ^ {2018/016139

?: 0.005 to 0.075%, and 0: 0.005 to 0.35 占 퐉.

The surface roughness (1/3) may be 0.7 or less.

The following equation 1 can be satisfied.

[Expression 1] 0.6 <[ _1/3] / [ _1/3]

(In the formula (1), 1 denotes the weight of the ratio contained in the steel sheet as a whole, and _1/3 denotes the weight of the grain bound to the surface portion of the steel sheet. Means the portion ranging from 0 to 1/4 or 31/4 to 기준 based on the thickness direction when the thickness of the steel sheet is 0 占 1)

The grain-oriented electrical steel sheet according to an embodiment of the present invention includes: 2.0% to 7.0%, 0: 0.005% to 0.1%, 0.006% or less (excluding 0%) and 0.001% to 0.5% : 0.003 to 0.1%, V: 0.03 to 0.5%,: 0.03 to 0.5%, 1: & cir & 0.03 to 0.5% and _10: comprises one or more of 0.03 to 0.5%, heating the slab, including the balance ₆ and unavoidable impurities; Hot rolling the slab to produce a hot rolled sheet; A step of cold-rolling the hot-rolled sheet to produce a hot-rolled sheet, a step of annealing the hot-rolled sheet by primary recrystallization, And secondary recrystallization annealing the primary recrystallization annealed steel sheet.

The slab may contain 0.003 to 1.4% of at least two of V,? ¾, ₆ and ₀ .

In the step of heating the slab, it can be heated to 1040 to 12801 ° C.

The primary recrystallized annealed steel sheet may contain 0: 0.005% or less (excluding 0%) and 0.015 to 0.05%.

The second recrystallization annealing step includes a heating step and a cracking step, and the cracking step may be performed at a temperature of 900 to 1250.

【Effects of the Invention】

The grain-oriented electrical steel sheet according to an embodiment of the present invention is extremely smooth in its surface due to the role of the components contained in the low-carbon steel components without the role of containing the specific additives in the conventional annealing separator control or annealing separator, 2019/132378 1 »(: 1 ^ {2018/016139

The surface properties of the electrical steel sheet can be controlled.

In addition, the directional electric steel sheet from which the forsterite coating has been removed can eliminate the main limiting factors of the magnetic migration, thereby improving the iron loss of the directional electric steel sheet,

Or deterioration in workability due to a glass coating film such as tetragonal oxide can be prevented.

DETAILED DESCRIPTION OF THE INVENTION

The terms first, second and third, etc. are used to describe various portions, components, regions, layers and / or sections, but are not limited thereto. These terms are only used to distinguish any moiety, element, region, layer or section from another moiety, moiety, region, layer or section. Thus, a first portion, component, region, layer or section described below may be referred to as a second portion, component, region, layer or section without departing from the scope of the invention.

Terminology used herein is simply intended to refer to a specific embodiment _and are not intended to limit the present invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified and that the presence or absence of other features, regions, integers, steps, operations, elements, and / It does not exclude addition.

Quot; or " on " another part, it may be directly on or over another part, or it may involve another part therebetween. By contrast, If it says that it is "directly above," there is no other part in it.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Unless otherwise noted,% means% by weight, and% 2019/132378 1 »(: 1 ^ {2018/016139

0.0001% by weight.

In the embodiment of the present invention, the term " further includes additional elements " means that the additional elements are replaced by an additional amount of the additional elements. Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Directional electric steel sheet

The grain-oriented electrical steel sheet according to an embodiment of the present invention comprises: 2.0 to 7.0%, 0 to 0.005% (excluding 0%), 0.0 to 0.05%, and 0.001 to 0.5% by weight, 0.03 to 0.5%, and 1: 0 to 0.03 to 0.5% of the total amount of at least one member selected from the group consisting of 0.03 to 0.5%, 0.005 to 0.1%, V: 0.03 to 0.5%, 0.03 to 0.5%, ₁₆ : 0.03 to 0.5% And the remainder

And inevitable impurities. First, the reasons for limiting the components of the grain-oriented electrical steel sheet will be described below. : 2.0 to 7.0 wt%

Silicon () is the basic composition of the electric steel sheet, which increases the specific resistance of the material, thereby lowering the core loss (1033), that is, the iron loss. If the content is too small, the resistivity may decrease and the iron loss property may be deteriorated. On the other hand, if the content is too large, the brittleness of the steel becomes large and cold rolling may become difficult. In the present invention, the content is not limited to that contained in the slab. It is not out of the scope of the present invention to use the diffusion method after powder coating or surface deposition and to contain the above-mentioned range in the final steel sheet.

0: 0.005% by weight or less

Carbon is needed in the manufacturing process but it is harmful in the final product. As austenite stabilizing element, 900

And at the same time, it suppresses the slab center segregation of 3 ₁₁ ^ _{111 ·} as well as the effect of miniaturization of coarse columnar structure occurring during the performance process.

In addition, it accelerates the work hardening of the steel sheet during hot rolling and promotes secondary recrystallization nucleation in the {110} <001 direction in the steel sheet. Therefore, there is no significant restriction on the addition amount, but when it is contained at less than 0.005% in the slab, 0 2019/132378 1 »(: 1 ^ 1 {2018/016139

A work hardening effect can not be obtained. When the content exceeds 0.10%, there may be a problem in work due to occurrence of hot-edge-crack. When cold rolling and decarburization annealing are performed, a load of the decarburization step is generated, so that the addition amount in the slab may be 0.005 to 0.10%.

C is decarburized in the first recrystallization annealing process, and the content of C in the final oriented electrical steel sheet is 0.005 wt% or less.

C is contained in the grain oriented electrical steel sheet according to an embodiment of the present invention in an amount of 0.005% or less. In the method for producing a grain-oriented electrical steel sheet according to an embodiment of the present invention, C is contained in the slab in an amount of 0.005 to 0.10%.

N: 0.001 to 0.05%

Nitrogen (When contained in a silver slab in an amount exceeding 0.006%, the size of the primary recrystallized grains is reduced to lower the secondary recrystallization initiation temperature, which causes secondary recrystallization not in {110} < 001 & It takes a long time to remove N from the secondary crack region of the final annealing process, and thus it is difficult to produce a highly directional electric steel sheet having high productivity. Therefore, the content of N in the slab is 0.006% or less.

In one embodiment of the present invention, after the first recrystallization annealing occurs, the content of the precipitate is 0.001 to 0.05%. That is, the content of N in the finally oriented electrical steel sheet is 0.001 to 0.05%. Specifically, it may be 0.001 to 0.006%.

In: 0.001 to 0.5¾

Indium (In) is segregated at the interface between the metal base material and the base coating layer at a temperature at which the base coating layer is formed as a mirror-polishing element. In is segregated at the interface, which causes a difference between the base coat layer and the metal base material. This is a phenomenon occurring in the entire steel sheet, so even if it is annealed at a high temperature in the form of a coil, the same segregation and segregation can be caused in the entire coil, so that a uniform surface can be obtained. It has a strong tendency to inversion, has a low freezing point, has a large difference in expansion coefficient between Fe and Fe, and can be appropriately used as a mirror surface source due to its large shrinkage upon solidification. Ba, Y, Sn, Sb, etc. are also good elements for segregation, but they do not have other requirements, so that the mirroring effect is not exerted. 2019/132378 1 »(: 1 ^ {2018/016139

When the content of III is less than 0.001%, the effect of mirroring is hard to be exerted. If it exceeds 0.5%, the rolling property may be deteriorated and the rolling crack may increase. Specifically, silver may contain 0.005 to 0.3%.

The directional electrical steel sheet according to one embodiment of the present invention can satisfy the following formula (1).

[Expression 1] 0.6 <[ _1/3] / [ _1/3]

(Formula 1, means the weight of the I :! included in the total for one steel sheet and rolling, 1 _¾ means the weight of the seokhan piece on the surface portion of the steel plate III. In addition, the incubation of the surface steel sheet thickness (^!) Quot; means a portion ranging from 0 to / 4 or 31/4 to & tilde &

If the weight ratio of III segregated to the surface portion of the steel sheet relative to the entire steel sheet is higher than 0.6, the difference between the base coating layer and the metal base material is caused to be high, and the mirroring effect can be sufficiently exhibited. In the following,

1 _{6, and} 1 1 ₀ will be described. A total of six elements are inhibitor auxiliary elements, which are related to the growth of primary recrystallization. However, the effect of improving the magnetic properties of the grain-oriented electrical steel sheet according to the purposes of the present invention can be expected.

&Lt; 0.03 to 0.5%

Copper (0 ₁₎ precipitates finely during hot rolling and can act as an inhibitor to the growth of primary recrystallized grains. On the other hand, the role of the inhibitor in secondary recrystallization is not significant _.

If it is less than 0.03%, 0 ₁ may be difficult to sufficiently inhibit excessive growth of the primary recrystallized grains. On the other hand, if it exceeds 0.50%, the size of the primary recrystallized grains becomes too small to lower the secondary recrystallization starting temperature, which can deteriorate the magnetic properties.

Bi: 0.005 to 0.1%

The bismuth (Mi) acts as an auxiliary inhibitor to increase the secondary recrystallization starting temperature and stably form secondary recrystallization, thereby producing a grain-oriented electrical steel sheet having excellent magnetic properties. If less than 0.005% 2019/132378 1 »(: 1 ^ {2018/016139

The effect is insignificant, and the iron loss improvement effect may be insignificant. On the other hand _, if it exceeds _0.1% _{, the} film deterioration can not be avoided and the magnetic property can be lowered _.

V, 此, 1 _{6, ¾ 10:} 0.03 to 0.5%

Vanadium (V), niobium (1 night)), tellurium ( ₆ ) and molybdenum (1 1 ₀ ) all act as inhibitor auxiliary components. However, if it is less than 0.03%, the effect of improving the secondary recrystallization is small and the effect of improving the magnetic characteristics is small because the suppressing power assist effect is insignificant. On the other hand, if it exceeds 0.5%, the suppressive force assisting effect becomes excessively large, the secondary recrystallization starting temperature is changed, and the magnetism may deteriorate.

On the other hand, (,,, V,

When the constituent element group includes two or more elements selected from the group consisting of V, 此, ⅙, _and ¾, the total amount of the elements can be controlled to 0.003 to 1.4%. If more than two elements are added, the role as auxiliary element of inhibitor can be strengthened. If the total amount is less than 0.003%, the effect of improving the inhibitory effect may be insignificant. If it exceeds 1.4%, the secondary recrystallization becomes unstable. have.

For example, when two kinds of V ,, _{16, and} 1 _" are included, the amount thereof may be 0.003 to 1.4%. V,), 1 _{6, and} 10, the amount thereof may be 0.003 to 1.4%. When all four species are included, the amount of the dog may be 0.003 to 1.4%.

The directional electrical steel sheet according to an embodiment of the present invention may further include 0.01 to 0.1% of Si, 0.005 to 0.9% and 0.005% or less of Si.

Yarn: 0.01 to 0.1%

Aluminum (Si) is finally

If it is less than 0.01% as a component acting as an inhibitor, a sufficient effect as an inhibitor can not be expected. If it exceeds 0.1%, the nitride of the watch tube will precipitate and grow too much, It can become scarce.

: 0.005 to 0.9%

Manganese (Mg) is a resistivity element and has an effect of improving the magnetic property. Therefore, it is required to have a Mn of 0.005% or more, but if it exceeds 0.9%, it may cause phase transformation after secondary recrystallization, which may adversely affect magnetism. 2019/132378 1 »(: 1 ^ {2018/016139

0.03% or less

If sulfur is added too much, the hot rolled. Cracks will be generated, so it can be added up to 0.03%.

The grain-oriented electrical steel sheet according to an embodiment of the present invention may further include at least one of 0.005 to 0.15% and 0.2%.

0.005 to 0.15%, and ¾ _{1: 0.005} to 0.2%

Antimony (¾) and tin (¾0) are low-temperature segregated elements and can assist in improving the degree of integration as an auxiliary role of existing precipitates. When it is excessively added, the crystal growth can be suppressed and the magnetic property can be lowered.

The grain oriented electrical steel sheet according to an embodiment of the present invention may further include at least one of I ⁵ : 0.005 to 0.075%, and 0.005 to 0.35%.

I ³ : 0.005 to 0.075%

Since the orientation steel sheet promotes the growth of the primary recrystallized grains in the low temperature heating type steel sheet, the secondary recrystallization temperature can be increased to increase the degree of integration of the {110} <001> orientation in the final product. On the other hand, I ⁵ increases the number of grains having a {110} < 001 > orientation in the primary re-crystal plate to lower the iron loss of the final product, As the {110} < 001 > density of the final product is improved, the magnetic flux density can also be increased.

In addition, I ³ segregates in grain boundaries to a high temperature of about 1000 ° (: when the secondary recrystallization annealing is performed, and also has an action of retarding the decomposition of the quartz material to reinforce the restraining force. In order for this action of I ³ to work properly, more than 0.005% is needed. However, when it exceeds 0.075%, the size of the primary recrystallized grains is rather reduced, so that the secondary recrystallization becomes unstable as well as the brittleness increases, which may hinder the rolling performance.

If the condition and? Are included at the same time, the following equation can be satisfied.

[Formula 2]

0.0370 <[1]] + 0.5 _{* [¾]} <0.0630

(In the formula 2, 奸] and [ū] mean the content (wt%) of I ³ and ¾ elements, respectively)

As a result, the iron loss and magnetic flux density of the grain-oriented electrical steel sheet can be further improved 2019/132378 1 »(: 1 ^ {2018/016139

have. When the content of [M + 0.5%] is controlled within the above-mentioned range, the iron loss improving effect can be further improved because the elements can be added together to obtain a synergistic effect, This is because, when satisfied, it is maximized discretely compared to other numerical ranges.

: 0.005 to 0.35%

Chromium (0) acts to grow primary recrystallized grains with a ferrite elongation element, and increases the grain in {110} < 001 > orientation in the primary recrystallized phase. It is necessary to make 0.005% or more, but if it exceeds 0.35%, a dense oxide layer may be formed on the surface of the steel sheet in the simultaneous decarburization and nitriding process, which may interfere with the soaking.

In addition, components such as 0 ₃ react with oxygen in the steel to form oxides, so strong suppression is required. Therefore, each component can be managed to 0.005% or less.

The grain-oriented electrical steel sheet according to an embodiment of the present invention may have an area ratio of crystal grains having a grain size of 1 占 or less of 10% or less. When a grain size of grain grains is 1 占 or less, the grain size of the secondary recrystallization is small, Can be improved

There are too many crystal grains having a crystal grain size of 1 占 or less and the orientation may be bad, and the larger the amount, the worse the magnetism may be. On the other hand, the average grain size of crystal grains having a grain size of 1 占 or less may be 3.5011 or less.

In addition, the directional electrical steel sheet according to an embodiment of the present invention may be a specular steel sheet.

The grain-oriented electrical steel sheet according to an embodiment of the present invention has a surface roughness of 0¾)

It is possible to smoothly remove the base coating layer by causing a difference between the base coating layer and the metal base material, and as a result, the surface roughness of 0,4) can be reduced. Surface roughness of 0 占 퐉) is small, thereby making it easy to move the magnetic domain, thereby further improving the magnetic properties.

Directional electric steel sheet manufacturing method

A method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention includes, 2019/132378 1 »(: 1 ^ {2018/016139

: 0.03 to 0.5%, R: 0.005 to 0.1%, V: 0.005 to 0.005% (excluding 0%), and 0.001 to 0.5% : 0.03 to 0.5%, ???: 0.03 to 0.5%, ??? ₆ : 0.03 to

0.03 to

0.5%, and further comprising the steps of: heating the slab containing the remainder? And unavoidable impurities; preparing a hot rolled sheet by hot rolling the slab; rolling the hot rolled sheet to produce a cold rolled sheet; A first recrystallization annealing step of the cold-rolled sheet, and a second recrystallization annealing step of the first recrystallization annealed steel sheet.

In the method for producing a grain-oriented electrical steel sheet according to an embodiment of the present invention, the slab may contain 0.003 to 1.4% of at least two of V,

Or 0.001 to 0.1%, and 0.005 to 0.9% and 0.005% or less.

Can further include one or more of 0.005 to 0.2% and, I ^3:: 0.005 to 0.15%, ₁ ¾ 0.005 to 0.075%, 0: can be further comprises one or more of 0.005 to 0.35%.

As for the composition of the slab, the reason for limiting the composition of the grain-oriented electrical steel sheet described above has been described in detail, and a repeated description thereof will be omitted. In the manufacturing process of the oriented electrical steel sheet, the remaining components except 0 and N are substantially unchanged.

First, the slab is heated. The slab heating temperature may be 1040 to 12801 :. If the heating temperature of the slab is increased, the manufacturing cost of the steel sheet is increased, and the heating furnace can be repaired by melting the surface of the slab and the lifetime of the heating furnace can be shortened. Therefore,

Or more to 1280 ° (: or less, it is possible to reduce the hot rolling cost and prevent the columnar structure of the slab from growing to a great extent, thereby preventing occurrence of cracks in the width direction of the plate in the subsequent hot rolling process The error rate can be improved.

Next, the heated slab is hot-rolled to produce a hot-rolled sheet. Hot rolling may be performed by hot rolling to a hot rolled thickness of 1.5 to 4.0 in thickness so as to obtain a final product thickness by applying an appropriate rolling ratio in the final cold rolling step. The hot rolling end temperature was 950

And cooling 2019/132378 1 »(: 1 ^ {2018/016139

Quenched by water to give 600

It can be taken up in the following.

Next, the hot-rolled sheet can be subjected to hot-rolled sheet annealing. It can be annealed at 1000 to 1200 ° (:).

Next, the hot-rolled sheet is cold-rolled to produce a hot-rolled sheet. Cold rolling is carried out by using a reverse (a cold rolling or a tandem (1 _{811 (} 1 ₀₁₁₁₎ rolling mill _{) with} a plurality of cold rolling methods including one or more intermediate rolling or intermediate annealing to produce a cold rolled sheet of the final product thickness . The cold-rolling can be carried out through a single coercive rolling to a final thickness of 0.1 to 0.5 占, specifically 0.15 to 0.35 占.

Next, the cold-rolled steel sheet is subjected to primary recrystallization annealing. At this time, decarburization occurs simultaneously. The primary recrystallization annealing should be carried out at 750

Or more for 30 seconds or more, the C content of the steel sheet can be reduced to 0.005% by weight or less. At the same time, an appropriate amount of oxide layer is formed on the surface of the steel sheet. In addition to decarburization, the deformed cold-rolled structure is recrystallized and crystals grow to a proper size. At this time, the annealing temperature and the cracking time may be adjusted so that the recrystallized grains grow.

During the primary recrystallization annealing process, sedimentation can occur. If the nitrogen content is too small, since the secondary recrystallization is difficult because the slab components in the nitrogen content is less than 15如claim ₁ case, the nitride nitrogen content through chimjil above 15 ^^, and too large amount of nitride to be fire exit defects are formed up to 50 ] ₃₀₁ or less. In other words,

The steel sheet after completion of the first recrystallization annealing includes 0.015 wt% to 0.05 wt%. Next, secondary recrystallization annealing is performed on the steel sheet after completion of the primary recrystallization annealing. The secondary recrystallization annealing includes a heating step and a cracking step which cause secondary recrystallization in the {110} < 001 > 0 ₀₃₈ orientation by raising at an appropriate heating rate. The temperature at the cracking stage can range from 900 to 125 kN.

If the crack temperature is 900

, Secondary recrystallization may not occur. On the other hand, if the crack temperature exceeds 12501 :, the magnetism may become dull due to surface layer deterioration.

In one embodiment of the present invention, the secondary recrystallization annealing is performed in the form of a batch, the annealing separator is applied to the steel sheet after the primary recrystallization annealing is completed, 2019/132378 1 »(: 1 ^ {2018/016139

It can be recrystallized and annealed. Conventionally, in the case of the glassy process, an additive such as chloride has been added to the annealing separator whose main component is? 0 or? ₂ O _{3. In} an embodiment of the present invention, the steel sheet itself contains a mirror- It is possible to separate the base coating layer smoothly without using any additives. That is, the annealing separator has a solid content

You can include it.

When the annealing separator is applied and secondary recrystallization annealing is performed, the surface oxide and the annealing separator react with each other to form a base coat. If the application of the first annealing separator mainly composed of 0 second, 1 \ 1 no _04, such as the case of forming the oxide coating increases as a main component ¾¾ and, applying an annealing separator primarily composed of hour _{2 (¾,} sieul An oxide coating layer is formed as a main component.

In an embodiment of the present invention, it may further include removing the base coating layer. As described above, in an embodiment of the present invention, the base coat layer can be smoothly removed by adding an appropriate amount of the mirror-surface reducing agent ₁₁ into the steel sheet, and the surface roughness of the steel sheet can be lowered after the removal. Physical or chemical methods can be used for removal.

Hereinafter, specific examples of the present invention will be described. However, the following examples are only illustrative examples of the present invention, and the present invention is not limited to the following examples.

Example

[Example 1]

It includes 0.004%, and, as a III inhibitors and the secondary element (, a, V,此, 1 _6, prepared a slab of the grain-oriented electrical steel sheet containing, as shown in Table 1 to the 1 _'0.

Thereafter, the steel sheet was heated at 115010 for 90 minutes, hot-rolled, quenched to 5801 ° C, annealed at 580 ° C for 1 hour, lyophilized, and hot-rolled to obtain a hot-

The hot-rolled sheet was heated to a temperature of 1040 ° C or higher, maintained at 9101 ° C for 80 seconds, quenched in boiling water, and pickled. The cold-rolled steel sheet was then rolled in the furnace and then heated to a temperature of 845 ° C in a mixed atmosphere of 63 to 67 ° (:) formed by simultaneous introduction of 50/50 of hydrogen and 50% of nitrogen 2019/132378 1 »(: 1 ^ {2018/016139

And maintained for 130 seconds to simultaneous decarburization nitriding (: 3 _^! ^ &Lt; / RTI >

This steel sheet was subjected to secondary recrystallization annealing by applying an annealing separator ¾ 0. A mixture atmosphere of 25% nitrogen + 75% hydrogen was used up to 1200 ° (: 1200

After reaching, it was maintained in a 100% hydrogen atmosphere for at least 15 hours, and then it was cooled. The forsterite layer formed on the surface of the steel sheet was removed by pickling.

The gloss of the surface measured for each condition is shown in Table 1 below. The degree of gloss was measured by measuring the amount of light reflected on the surface at an angle of reflection of 60 ° using a measuring machine of _{1 to 3. The} degree of gloss was less than 20, the degree of deficiency was 20 to 200, The case was marked as very good. Further, surface roughness (1/3) was measured.

[Table 1]

As shown in Table 1, in Examples 1 to 6, the content according to the present invention was satisfied, the content of the inhibitor-assisted element was satisfied, and the gloss was excellent. Also, the surface roughness was 0.7_ or less.

On the other hand, in the case of Comparative Example 1, the addition was not made and the gloss was found to be defective and the illuminance exceeded 0.7. In the case of Comparative Example 2, 2019/132378 1 »(: 1 ^ {2018/016139

III was excessively added and the rolling was impossible.

[Example 2]

0.1, and 0.004%, and a slab of a grain-oriented electrical steel sheet containing antimony ( _{VI, VI, VI, VI)} as an inhibitor auxiliary element as shown in Table 2 below.

Then, it was heated at 11501: for 90 minutes, then subjected to hot rolling

Quenched to 580 하여, annealed at 580 for 1 hour, lyophilized and hot rolled to produce a 2.3 ₁ 두께 thick hot rolled sheet.

The hot-rolled sheet was heated to a temperature of 1040 or more, maintained at 910 ° (for 80 seconds, quenched in boiling water, and pickled. The cold-rolled steel sheet was then heated at 845 ° C for 130 seconds in a mixed atmosphere of a dew point temperature of 63 to 67 formed by simultaneous charging of 50% hydrogen and 50% nitrogen. And then subjected to simultaneous decarburization and nitriding treatment to obtain a value of (3 is less than 3 tiles and N is 19).

This steel sheet was subjected to secondary recrystallization annealing by applying an annealing separator, First Step.

The mixture atmosphere was 25% nitrogen + 75% hydrogen until 1200, and after reaching 120010

Maintained in a 100% hydrogen atmosphere for at least 15 hours, and then subjected to furnace cooling. The forsterite layer formed on the surface of the steel sheet was removed by pickling.

The magnetic properties measured for each condition are shown in Table 2 below. The prepared steel sheet was prepared by the conventional method. 1 to ₆₃ to measure the iron loss _17/5 ()) until the croissant magnetization are summarized in Table 2 below.

[Table 2]

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As shown in Table 2, the inventive examples 7 to 9 satisfied the composition of the present invention and exhibited low values of iron loss. On the other hand, in Comparative Example 3, the inhibitor auxiliary element was not added, so that the iron loss value was higher than that of the inventive example. In Comparative Example 4, the amount of Fe was excessively added and the iron loss value was higher than that of the invention.

In Examples 10 to 12, iron content was lower than that of Comparative Example 5, while iron content was lower than that of Comparative Example 5 by adding less than 0.005% of iron. In Comparative Example 6, bivalent recrystallization was not formed due to excessive addition of bivalent ions.

In Inventive Example 13, the content of V satisfied the composition of the present invention, and the iron loss was low. On the other hand, in Comparative Example 7, less than 0.03% thereof was added, and the iron loss value was higher than that of the invention. Comparative Example 8 was excessively added, and the iron loss value was higher than that of the inventive example.

Inventive Example 14 shows that the content thereof satisfies the composition of the present invention, 2019/132378 1 »(: 1 ^ {2018/016139

Respectively. On the other hand, in Comparative Example 9, less than 0.03% thereof was added, and the iron loss value was higher than that of the invention. The iron loss value of the comparative example 1? Was excessively higher than that of the inventive example.

In Inventive Example 15, the content of roots satisfies the composition of the present invention and exhibits a low value of iron loss of 5. On the other hand, in Comparative Example 11, less than 0.03% of ^ 7 was added, and the iron loss value was higher than that of the comparative example. In Comparative Example 12, 7 ₆ was excessively added, so that the iron loss value was higher than in the case of the invention.

In Inventive Examples 16 and 17, the content of ₀ satisfied the composition of the present invention and the iron loss value was low, whereas in Comparative Example 13, the content of ¾ was added to less than 0.03%, and the iron loss value was higher than that of 10. In Comparative Example 14, ¾ was excessively added, and the iron loss value was higher than in the case of the invention.

It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. It will be understood that the invention may be embodied in other specific forms without departing from the spirit or scope of the invention. It is to be understood, therefore, that the embodiments and / or the examples described above are illustrative in all respects and not restrictive.

Claims

2019/132378 1 »(: 1 ^ {2018/016139

Claims:

Claim 11

By weight, from 2.0% to 7.0%, 0: 0.005% (excluding ◦%), 0.001% to 0.05%, and 0.001% to 0.5%

(Furnace: 0.03 to 0.5%, fine: 0.005 to 0.1%, V: 0.03 to

0.03 to 0.5%, ₁₆ : 0.03 to 0.5% and

0.03 to 0.5% by weight,

And an inevitable impurity.

[Claim 2]

The method according to claim 1,

V, and _6, and at least two of them: 0.003 to 1.4%.

[3]

The method according to claim 1,

Hour: 0.01 to 0.1%,

0.005 to 0.9% and 0.03% or less (excluding 0%).

[4]

The method according to claim 1,

0.005 to 0.2%. &Lt; / RTI >

[Claim 5]

The method according to claim 1,

?: 0.005 to 0.075% and 0: 0.005 to 0.35%.

[Claim 6]

The method according to claim 1,

The surface roughness (1 degree) is not more than 0.7.

7.

The method according to claim 1,

A directional electrical steel sheet satisfying the following formula (1). 2019/132378 1 »(: 1 ^ {2018/016139

[Expression 1] 0.6 <[ _1/3] / [ _1/3]

(In the formula (1), 1 _¾ means the weight of the ratio contained in the steel sheet as a whole, and 1 _¾ means the weight of III segregated on the surface portion of the steel sheet.

Means a portion ranging from 0 to 1/4 or from / 4 to 1 on the basis of the thickness direction when the thickness of the surface-coated steel sheet is 1).

[8]

(Excluding 0%) and a ratio of 0.001% to 0.5%, (: 0.03% to 0.5%, and 0.005% to 0.005% by weight) to 0.1%, V: 0.03 to 0.5%,此: 0.03 to _0.5¾>, ₆ 1: 0.03 to 0.5% and 1 \ 10: comprises one or more of 0.03 to 0.5%, the balance including inevitable impurities and muscle Heating the slab;

Hot rolling the slab to produce a hot rolled sheet;

Cold-rolling the hot-rolled sheet to produce a cold-rolled sheet;

Subjecting the cold-rolled sheet to primary recrystallization annealing; And

And annealing the primary recrystallization annealed steel sheet for secondary recrystallization annealing.

[Claim 9]

In Item 18,

The slabs

V, an additive, and at least two of ₆ and 1 10 ₀ : 0.003 to 1.4%.

Claim 10

9. The method of claim 8,

In the step of heating the slab,

1040 to 12801 :.

Claim 11

9. The method of claim 8,

The first recrystallized annealed steel sheet contains 0: 0.005% or less (excluding 0%) and 0.015% to 0.05%.

Claim 12 2019/132378 1 »(: 1 ^ {2018/016139

9. The method of claim 8,

Wherein the second recrystallization annealing step comprises:

A heating step and a cracking step,

Wherein the cracking step is performed at a temperature of 900 to 1250 < 1 >.