KR100481368B1 - A method for manufacturing low temperature reheated grain-oriented electrical steel sheet having superior punching property - Google Patents

Abstract

The present invention relates to a grain-oriented electrical steel sheet produced by applying the low-temperature slab heating method during hot rolling operation, in the manufacturing method of the grain-oriented electrical steel sheet by using a mixed annealing separator that minimizes the addition of chloride by mixing MgO and SiO ₂ Thus, to provide a method for producing a grain-oriented electrical steel sheet having excellent coating workability, no glass coating, and excellent punchability, which has an object.

In the present invention, in terms of weight%, Si: 2.9 to 3.4%, C: 0.045 to 0.062%, P: 0.015 to 0.035%, dissolved Al: 0.022 to 0.032%, N: 0.006 to 0.009%, S: 0.004 to 0.010%, Steel slab composed of Mn: 0.008 ~ 0.012%, Cu: 0.012 ~ 0.021%, and balance Fe and other unavoidable impurities are re-heated at a temperature of 1150 ~ 1200 ℃ and hot rolled, and the temperature is below 1100 ℃. Hot-rolled sheet annealing, cold-rolled to pickling and final thickness, and then subjected to simultaneous decarbonation treatment in the wet atmosphere of hydrogen and nitrogen mixture containing ammonia gas in the vicinity of 840 ~ 890 ℃, coated with annealing separator 700 After drying at a temperature of less than ℃ ℃ wound with a large coil, while maintaining the temperature rising rate of 700 ~ 1200 ℃ section 15 ℃ / hr or more while cracking at a temperature of 1190 ~ 1210 ℃ for more than 20 hours to perform a high-temperature finish annealing In the method for producing a grain-oriented electrical steel sheet by applying a tension coating agent,

The application of the annealing separator is selected from the group consisting of MgO and 5 to 20% of fine SiO ₂ powder or colo SiO ₂ of the month state for a MgO based on solids, CuCl _2, MgCl _2, and NiCl ₂ 1 paper 0.008 The technical gist of the present invention relates to a method for producing a low-temperature reheat oriented electrical steel sheet having excellent punching characteristics, which is added at a total oxygen content (ppm) ± 0.2 of the decarburized plate surface.

Description

Method for manufacturing low-temperature reheating oriented electrical steel with excellent punching characteristics {A METHOD FOR MANUFACTURING LOW TEMPERATURE REHEATED GRAIN-ORIENTED ELECTRICAL STEEL SHEET HAVING SUPERIOR PUNCHING PROPERTY}

The present invention relates to a method for producing a grain-oriented electrical steel sheet produced by applying a low-temperature slab heating method during hot rolling, and more particularly, by applying an annealing separator composed of MgO, SiO ₂ and metal chloride, The present invention relates to a method for producing a grain-oriented electrical steel sheet having excellent punching property with improved vocalization and improved magnetic properties.

A grain-oriented electrical steel sheet is an electrical steel sheet having an aggregate structure in which the grain orientation is aligned in the (110) [001] direction. The grain-oriented electrical steel sheet has extremely excellent magnetic properties in the rolling direction, so that cores of transformers, electric motors, generators, and other electronic devices are used. Used as a material.

In general, a grain-oriented electrical steel sheet is a steel slab made of 2-4% silicon and MnS, AlN, etc., mostly as a grain growth inhibitor, and is subjected to one time with (reheating and hot rolling)-(preliminary annealing)-(intermediate annealing). Cold rolling)-(Decarbon annealing)-(Annealing separator application)-(final finishing high temperature annealing) The most difficult process among these complex manufacturing processes is the slab reheating process that performs high temperature heat treatment. In this step, the steel slab is maintained at a high temperature of about 1400 ° C. for about 5 hours to completely disperse the precipitates such as MnS and AlN, which are used as grain growth inhibitors, and then deposit finely. At this time, an oxide called Pyrite (Fe ₂ SiO ₄ ) is formed on the surface of the hot slab. Since the melting point is about 1340 ° C. and it melts from the surface, some of them are designed to flow outward, but most of them are refractory parts of the furnace. Accumulation causes work to be terminated and internal repairs are inevitable.

In order to solve the above problems, efforts have been made to improve the slab reheating temperature. As a result, Korean Patent Application No. 93-23751 sets up a component system for performing hot rolling by heating a conventional grain-oriented electrical steel sheet in the vicinity of 1250 ~ 1340 ° C, and in a manufacturing method that can work without additional equipment supplementation or establishment in the existing manufacturing process. The invention has been disclosed. In addition, Korean Patent Application No. 97-37247, Korean Patent Application No. 97-28305, and Korean Application Publication No. 90-7447 disclose that they can be processed at 1200 ° C or lower, and currently produce products having excellent magnetic and surface quality characteristics. Doing.

However, there is a problem that the punchability is not good in the production of the iron core core for the transformer because the glass coating is present in the oriented electrical steel sheet manufactured as described above. That is, the iron core for transformer using the oriented electrical steel sheet manufactured as described above In the case of manufacturing cores, real users perform slitting, punching, heat treatment and assembly, among which punching is the most important manufacturing process in terms of productivity and cost reduction. When punching the directional product at demand, the punchability is divided into three materials: the hardness of the material itself, the glass film (the primary component is a Forsterite (2MgO · SiO ₂ )) layer, and the tension coating layer (the second insulating film). Mostly determined by. The glass coating layer is formed on the surface of the material by reaction between MgO used as an annealing separator during high temperature annealing for secondary recrystallization and SiO ₂ oxide on the surface of the material. It is preferable that it is a single coating layer only of the tension coating layer without a coating layer. Accordingly, much attention and research and development have been made regarding the manufacture of oriented electrical steel sheet without glass film.

Such efforts are being promoted in two directions. First, MgO is used as the main component of the annealing separator in the same manner as the conventional method, and chlorides such as Ca, Li, K, Na, and Ba are added thereto, and these chlorides react with the surface of the material during high temperature annealing to form a FeCl ₂ film. After the evaporation is removed from the surface by forming, the US Pat. No. 4875947 is representative of the invention which blocks the formation of the glass coating layer itself. However, according to the present invention, the coating workability is excellent, but it is difficult to strictly control and control the oxide layer to completely remove the glass coating, and iron loss is more severe than that of the product where the glass coating layer is formed due to the overetching action due to the chloride addition. There is a deteriorated problem.

As another method, there is a method of applying Al ₂ O ₃ powder which has no reactivity with the oxide layer on the surface of the material as an annealing separator, but the Al ₂ O ₃ powder is commercially commercially crushed into ultra fine particles. Only about 2 to 10 µm can be refined, and there is a problem that it is difficult to keep this powder in a dispersed state with water. In order to solve this problem, Japanese Patent Laid-Open No. 6-136555 discloses a method of applying Al ₂ O ₃ powder to an organic solvent by mixing the Al ₂ O ₃ powder with an organic solvent or the like. It is impossible to stably exist in a dispersed state, and has a problem of polluting the environment by volatilization of an organic solvent during drying of the slurry. Therefore, Japanese Patent Laid-Open No. 6-41642 discloses an electrostatic coating method, but commercial production is difficult due to equipment limitations.

Accordingly, the present inventors have conducted research and experiments in order to solve the above-mentioned problems of the prior arts, and based on the results, the present invention proposes the present invention at the time of high temperature annealing in the method of manufacturing a grain-oriented electrical steel sheet. By using annealing separator that minimizes the addition of chlorides by mixing and adding SiO ₂ which is highly reactive with MgO as annealing separator, it is intended to provide a method for producing a grain-oriented electrical steel sheet having good coating workability and no glass coating and excellent punchability. , Its purpose is.

The present invention for achieving the above object by weight, Si: 2.9 ~ 3.4%, C: 0.045 ~ 0.062%, P: 0.015 ~ 0.035%, dissolved Al: 0.022 ~ 0.032%, N: 0.006 ~ 0.009%, S : 0.004 ~ 0.010%, Mn: 0.008 ~ 0.012%, Cu: 0.012 ~ 0.021%, and steel slabs composed of the balance Fe and other inevitable impurities are reheated at a temperature of 1150 ~ 1200 ℃ and hot rolled. , Hot-rolled sheet annealing at a temperature of 1100 ℃ or less, cold rolling to pickling and final thickness, and then subjected to simultaneous decarbonation treatment in a wet atmosphere of hydrogen and nitrogen mixture containing ammonia gas in the vicinity of 840 ~ 890 ℃, annealing After applying the separating agent and drying at a temperature of 700 ℃ or less and winding it with a large coil, it is cooled after cracking for 20 hours at a temperature of 1190 ~ 1210 ℃ while maintaining the temperature rising rate of 700 ~ 1200 ℃ over 15 ℃ / hr. In the method of producing a grain-oriented electrical steel sheet by performing a high temperature annealing, applying a tension coating agent

The application of the annealing separator is selected from the group consisting of MgO and 5 to 20% of fine SiO ₂ powder or colo SiO ₂ of the month state for a MgO based on solids, CuCl _2, MgCl _2, and NiCl ₂ 1 paper 0.008 The present invention relates to a method for producing a low-temperature reheat oriented electrical steel sheet having excellent punching characteristics, which is added at a total oxygen content (ppm) ± 0.2 of the decarburized plate surface.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

When machining and assembling the core core for transformer at the demand price, the punching property, which is the most required characteristic for cost reduction and productivity improvement, is known as a punching machine capable of working with the same mold, that is, a conventional burr with one mold. It is evaluated by the number of punches up to 50 m. In order to improve the punchability, various methods have been adopted and applied. Among them, it has been found that the use of a grain-oriented electrical steel sheet product without a glass coating is a very effective method.

The glass film is a type of insulating film formed by a forsterite formation reaction (2MgO.SiO ₂ ), and MgO applied as a main component of the annealing separator reacts with SiO ₂ and FeSiO ₄ , which are oxide layers on the material surface. Formed, which is explained chemically.

In the temperature range of 250 ~ 650 ℃ during high temperature annealing, MgCl ₂ decomposition reaction occurs as shown in Scheme 1 to generate HCl gas.

MgCl ₂ 6H ₂ O → MgO + 2HCl ↑ + 5H ₂ O

At this time, the decomposed HCl gas reacts with Fe as in Scheme 2 below.

Fe + HCl → FeCl ₂

Next, in the temperature range of 950 ~ 1150 ℃, the glass film is formed through the reaction of Scheme 3.

The surface oxide layer of the material _{SiO 2 + MgO → 2MgO · SiO} 2

At this time, FeCl ₂ formed on the surface of the raw material according to the reaction formula 2 is melted and scattered together with the glass coating layer in the upper portion at a temperature section of 1150 to 1200 ° C, and it is estimated that the glass coating layer is removed.

However, even if the chloride is added, it is difficult to completely remove the glass film reactant formed essentially unevenly, so that the addition of excess chloride is inevitable. This excess addition of chloride causes excessive scattering of the surface layer to roughen the surface and at the same time deteriorate the magnetism.

Thus, the present inventors, while studying a method for minimizing the amount of chloride of the metal acting as a reactant remover in MgO, when the ultra-fine SiO ₂ particles having excellent reactivity with MgO is mixed and added to the annealing separator, It has been found that the addition of metal chlorides can be minimized by inhibiting or inhibiting the glass film formation reaction between MgO and SiO _{2 on the} surface of the material during annealing, and thus, the present invention has been completed.

That is, the MgO is there and particulate SiO ₂ and the material SiO ₂ in the surface oxide layer in the mixture to react at the same time, of the self cross-reaction rate since the SiO ₂ in the oxide layer is an amorphous and fine-grain powder SiO ₂ mixed addition of crystalline SiO ₂ of the oxide layer is rather fast. However, since the mixed-added fine SiO ₂ is relatively large and exists near MgO, it is possible to suppress MgO from reacting with SiO ₂ in the oxide layer to form a glass film. Accordingly, since the amount of chloride added in the initial annealing separator can be somewhat reduced, the surface etching is reduced in the final product, thereby improving the surface roughness and improving the iron damage effect, and can obtain a product without the glass coating.

In the annealing separator composition, the fine powder or the colloidal SiO ₂ serving as an interfacial reaction inhibitor is preferably 5 to 20% based on the solid content. This is because, when the SiO ₂ is added in less than 5%, the effect is less, and when added in excess of 20%, the coating workability is worse. Further, the fine SiO ₂ powder or colo SiO ₂ is effective, even in the state of the month has its own viscosity, and ensuring stability of the liquid slurry.

On the other hand, metal chlorides used as the reactant remover of the glass film have a reaction blocking ability, but it is preferable to use one of CuCl ₂ , NiCl ₂ , and MgCl ₂ having excellent compatibility with MgO as a main component. At this time, considering that the glass film is a reaction product between MgO and SiO ₂ content on the surface of the material, it should be added in proportion to the amount of SiO ₂ present on the surface to minimize iron loss deterioration due to excessive addition. The SiO ₂ content in the surface oxide layer is difficult to quantitatively analyze, and it takes a long time to analyze, and thus, the total oxygen amount that can be easily analyzed is analyzed and applied. Even in this way, it was confirmed that there was no significant difference in the stable state of the furnace sulfur in the annealing furnace.

Accordingly, the inventor of the present invention is to investigate the relationship between the total amount of oxygen on the surface of the material and the appropriate amount of chloride to derive the following equation 1.

[Relationship 1]

Chloride Addition (%) = 0.008 × Material Surface Total Oxygen (ppm) ± 0.2

As shown in Equation 1, it can be seen that the chloride is at least 0.2%, which is the minimum amount necessary for maintaining the liquid viscosity of the coating slurry and at the same time considering the amount of Fe and Si-based oxide film that may be additionally formed during high temperature annealing. It is also the minimum amount. In addition, it was confirmed that there was almost no iron loss deterioration at this amount.

Accordingly, the present invention provides an annealing separator in which MgO is mixed with SiO ₂ in a powder or colloidal state as a reaction inhibitor, and one of reactants remover CuCl ₂ , MgCl ₂ , and NiCl ₂ is added according to Equation 1 above. By coating with a co-tarol, it is possible to produce an aromatic product having no glass film during the hot annealing thereafter.

Hereinafter, the reason for range limitation of the present invention steel will be described.

The C is an element that plays a role of fine solid dispersion of AlN precipitates, rolled structure formation, imparting processing energy during cold rolling, etc., which is advantageously up to 0.045% or more, but it is advantageous to upwardly manage as much as possible. It is preferable to add at 0.062%.

The Si is an element that serves to lower the iron core loss by increasing the resistivity value, the iron loss characteristics are worse when the content is less than 2.9%, the steel is vulnerable if added more than 3.4%, cold rolling is extremely bad, 2.9 ~ Preference is given to adding at 3.4%.

The Mn is an element that lowers the solid solution temperature of the precipitate upon reheating and prevents cracks formed at both ends of the material during hot rolling, and should be added at least 0.008% but is added to the Mn oxide when more than 0.012% is added. This makes iron loss worse, so the upper limit is made 0.012%.

The dissolved Al forms a precipitate of AlN together with N to secure the grain growth inhibitory power. If the content is less than 0.022%, it does not have sufficient inhibitory power required for secondary recrystallization, resulting in small grain size and incomplete fine particles.If more than 0.032% is added, the inhibitory power is too strong, making secondary recrystallization itself difficult and rapidly deteriorating magnetic properties. In this invention, it is preferable to limit the amount to 0.022 to 0.032%.

The N is an essential component for forming the secondary precipitates by forming reaction precipitates with dissolved Al, the content of which is set to the lower limit of 0.006% in consideration of the formed precipitate, and to set the upper limit to 0.009% in consideration of the subsequent sedimentation. desirable.

Cu is combined with S, an impurity component, to form a Cu ₂ S precipitate, and at least 0.012% of the solid solution is dissolved at the lowest temperature of the precipitate. However, when more than 0.021% is added, it is preferable to set the upper limit to 0.021% because the oxide formed during decarbonization annealing adversely affects the insulation film formation.

Next, the manufacturing process will be described.

The steel slab having the above-described composition is hot-rolled after hot reheating in the range of 1150 ° C. to 1200 ° C. in consideration of hot rolling and magnetic properties to secure the hot rolled sheet. Thereafter, hot-rolled sheet annealing is performed at a temperature of 1100 ° C. or lower, pickled and cold rolled to a final thickness, and then subjected to simultaneous decarbonation treatment near 840 to 890 ° C. under a wet atmosphere of hydrogen and nitrogen mixture containing ammonia gas. Do it. Then, as a fusion coating agent, a slurry mixture composed of MgO, SiO ₂ and chloride is applied with cotarrol.

Then, it is wound up to 700 ° C or less, made into a large coil, and then subjected to final finishing annealing. For example, the final finishing annealing is performed by cooling after cracking for 20 hours or more at a temperature of 1190 to 1210 ° C. while maintaining a temperature rising rate of 700 ° C. to 1200 ° C. or more at 15 ° C./hr or more, at this time, 1200 ° C. The temperature range up to is a hydrogen atmosphere containing 25% or less, and the crack section at 1200 ° C. and subsequent cooling are performed in a 100% hydrogen atmosphere.

As described above, the final finishing high temperature annealing is performed to complete the secondary recrystallization and pickling treatment to adjust the surface, and finally apply a tension coating agent, the composition of the tension coating agent is not particularly limited in the present invention, for example A tension coating agent consisting of phosphate, colloidal silica and chromic anhydride can be applied. Then, it is dried to manufacture an electrical steel sheet product.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Reheat the steel slab consisting of 3.15% Si, 0.052% C, 0.015% P, 0.028% dissolved Al, 0.0069% N, 0.005% S, 0.012% Mn, 0.015% Cu, and balance Fe by weight at 1150 ° C After that, hot-rolled sheet annealing was performed at a temperature of 1100 ° C. or lower, followed by pickling and cold rolling to obtain a final thickness of 0.35 mm. Thereafter, simultaneous decarbonation treatment was performed at a temperature of 875 ° C under a humid atmosphere of 25% hydrogen + 75% nitrogen gas containing 0.5% ammonia gas to adjust the amount of residual carbon and nitrogen and at the same time, the total oxygen content of the surface was 600 ppm. An annealing plate was obtained. Subsequently, the annealing separator was applied. The conventional material is a composition in which TiO ₂ 2.5% is added to MgO, and the comparative material and the invention material are added 4.8% by varying the type of chloride as shown in Table 1 below, and fine SiO ₂ powder is added thereto. The composition added 15% was slurry-coated and applied with cotarrol. Then, after drying and winding at a temperature of 700 ℃ or less to produce a large coil, the final finishing high temperature annealing was performed. Final finishing high temperature annealing, the temperature range up to 1200 ℃ is the nitrogen-containing hydrogen atmosphere of 25% or less, the 1200 ℃ crack section and the subsequent cooling is 100% hydrogen atmosphere, the temperature increase rate of 700 ~ 1200 ℃ section 15 ℃ It was set as the heat cycle to cool after cracking for 20 hours or more at the temperature of 1200 degreeC, maintaining more than / hr. Finally, a tension coating agent composed of phosphate, colloidal silica and chromic anhydride was applied to prepare a grain-oriented electrical steel sheet.

The formation state, magnetic properties and punchability of the glass film were measured for these, and the results are shown in Table 1 below. Formation state of the glass film was visually observed, and magnetic properties were evaluated by measuring iron loss (W _17/50 ) and magnetic flux density (B ₁₀ ) with a single plate measuring instrument. It evaluated by measuring by the number of punches until it became 0.05 mm.

division Type of chloride Glass film formation amount (g / ㎡) Surface appearance magnetism Punching (manta) Magnetic flux density (T) Iron loss (W / kg) Conventional Materials 1 － 4.3 Gray, uniform 1.91 1.11 1.2 Invention 1 CuCl ₂ 0 Bright, uniform 1.91 1.08 3.7 Invention 2 MgCl ₂ 0 Bright, uniform 1.92 1.09 3.6 Invention 3 NiCl ₂ 0 Bright, uniform 1.91 1.08 3.6 Comparative Material 1 CaCl ₂ 2.8 Bright, stain 1.91 1.10 2.1

As shown in Table 1, the glass material is formed in the conventional material (1), it can be seen that the number of punches is less than 120,000 strokes, and the iron loss is also high. However, the present inventions (1) to (3) were not only excellent in punchability but also relatively good in magnetism.

In Comparative Material (1) using CaCl ₂ as chloride, the glass film was slightly formed, and the punching number was smaller than that of the present invention.

Example 2

The decarburization-nitride annealing time was adjusted with respect to the primary annealing plate of Example 1 to obtain total oxygen on the material surface of 450 ppm and 600 ppm, respectively. Subsequently, as a high-temperature annealing annealing agent, 12% of colloidal SiO ₂ was added to MgO powder based on solid content, and the composition in which the amount of CuCl ₂ was changed as shown in Table 2 below was applied as a slurry and coated with cotarol. , And dried at a temperature of 700 ℃ or less and wound up with a large coil. Thereafter, the final high temperature annealing of Example 1 was performed and a tension coating agent was applied to produce a grain-oriented electrical steel sheet. Formation state, magnetic properties and punchability of the glass coating were measured for these results, and the results are shown in Table 2 below.

division Total oxygen (ppm) CuCl ₂ addition amount (%) Surface appearance magnetism Punching (manta) Magnetic flux density (T) Iron loss (W / kg) Comparative Material 2 450 － Partial film remaining 1.92 1.12 2.1 Invention 4 3.5 Bright and uniform 1.92 1.08 3.6 Comparative Material 3 4.5 Bright and uniform 1.91 1.13 3.5 Comparative Material 4 600 3.3 Surface stain 1.91 1.10 3.2 Invention 5 4.8 Bright and uniform 1.92 1.08 3.8 Comparative Material 5 5.8 Bright and uniform 1.92 1.12 3.7

As shown in Table 2, the comparative material (2) was not added to the chloride content of 450ppm total oxygen on the surface of the material, the glass film remained and magnetic and punchability also deteriorated compared to the invention material. On the other hand, the comparative material (3) in which the chloride was added excessively deteriorated due to the overetching phenomenon.

Comparative material (4) showed a small value of the addition of chloride to leave stains on the surface and the punchability is lower than the present invention. On the other hand, the comparative material 5 had excessive iron loss due to the excessive addition of chloride, and deteriorated magnetic properties.

On the other hand, the invention materials (5) and (6) of the present invention had no glass film formed, the surface was bright and uniform, and had excellent magnetic and punching properties.

Example 3

4.8% of MgCl ₂ was added as a high-temperature annealing annealing agent with respect to the first annealing plate of Example 1, and the composition and the amount of SiO ₂ were changed as shown in Table 3 below. It was applied with a roll, dried at a temperature of 700 ° C. or lower, and then wound with a large coil. Thereafter, the final high temperature annealing of Example 1 was performed and a tension coating agent was applied to produce a grain-oriented electrical steel sheet. Formation state, magnetic properties and punchability of the glass coating were measured for these and the results are shown in Table 3 below.

division SiO ₂ Surface appearance magnetism Punching (manta) Kinds Addition amount (%) Magnetic flux density (T) Iron loss (W / kg) Conventional material 2 － 0 Remaining film 1.91 1.11 2.5 Comparative Material 6 Fine powder 2 Partial stain 1.91 1.08 3.1 Invention 7 Fine powder 7 Bright and uniform 1.92 1.09 3.6 Invention Material 8 Colloidal 10 Bright and uniform 1.92 1.08 3.6 Invention 9 Colloidal 15 Bright and uniform 1.91 1.09 3.7 Comparative Material7 Fine powder 30 Surface irregularity 1.92 1.10 3.3

As shown in Table 3, it can be seen that the conventional material (2) to which no reaction inhibitor is added and the comparative material (6) having a small amount of addition do not have good surface appearance and punchability. On the other hand, the comparative material 7 in which the fine powder of SiO ₂ was excessively added was uneven in appearance color and also inferior in punchability compared to the present invention.

On the other hand, the invention materials (7) to (9) of the present invention had good appearance, magnetic properties, and punchability.

As described above, by using the annealing separator as a mixed slurry of MgO, SiO ₂ , and chloride according to the present invention, there is no glass coating on the surface of the hot slab, thereby obtaining a grain-oriented electrical steel sheet having excellent punching and magnetic properties. It works.

Claims (1)

By weight, Si: 2.9-3.4%, C: 0.045-0.062%, P: 0.015-0.035%, dissolved Al: 0.022-0.032%, N: 0.006-0.009%, S: 0.004-0.010%, Mn: 0.008 Steel slab composed of ~ 0.012%, Cu: 0.012 ~ 0.021%, and the remaining Fe and other unavoidable impurities are reheated at a temperature of 1150 to 1190 ° C., and hot rolled, and hot rolled at a temperature of 1100 ° C. or less. After annealing and cold rolling to pickling and final thickness, simultaneous decarbonation treatment is carried out in the wet atmosphere of hydrogen and nitrogen mixture containing ammonia gas in the vicinity of 840 ~ 890 ℃, and the annealing separator is applied to below 700 ℃ After drying at a temperature, wound with a large coil, followed by finishing high temperature annealing to cool after cracking at a temperature of 1190 to 1210 ° C for at least 20 hours while maintaining a temperature rising rate of 700 to 1200 ° C over 15 ° C / hr. In the method for producing a grain-oriented electrical steel sheet by applying, The application of the annealing separator is selected from the group consisting of MgO and 5 to 20% of fine SiO ₂ powder or colo SiO ₂ of the month state for a MgO based on solids, CuCl _2, MgCl _2, and NiCl ₂ 1 paper 0.008 A method for producing a low-temperature reheat oriented electrical steel sheet having excellent punching characteristics, which is added at a total oxygen content (ppm) ± 0.2 of the decarburized plate surface.