KR102043525B1 - Thin non-oriented electrical steel sheet having excellent magnetic properties and shape and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a thin non-oriented electrical steel sheet excellent in magnetic properties and shape and a method of manufacturing the same.
One embodiment of the present invention is by weight, C: 0.0005 to 0.010%, Si: 0.2 to 2.5%, Al: 0.03 to 1.0%, Mn: 0.03 to 1.5%, P: 0.002 to 0.10%, S: 0.0002 to 0.01%, Sn: 0.0005 ~ 0.1%, Ca: 0.0005 ~ 0.01%, N: 0.0005 ~ 0.010%, balance Fe and other unavoidable impurities, the grain average size of the ferrite is 20-100㎛, the width of the strip Provided is a thin non-oriented electrical steel sheet having excellent magnetic properties and shapes in which the lateral thickness deviation Δt _CR satisfies the following relational expression 1 and a method of manufacturing the same.
[Relationship 1] Δt _CR / 1-0.03S + 11t ≤ 1.6
(Where Δt _CR is the thickness variation in the width direction of the strip (μm), S is the thickness measurement position (mm) at a point away from the strip width direction edge, and t means the thickness of the strip (mm)). )

Description

THIN NON-ORIENTED ELECTRICAL STEEL SHEET HAVING EXCELLENT MAGNETIC PROPERTIES AND SHAPE AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a thin non-oriented electrical steel sheet excellent in magnetic properties and shape and a method of manufacturing the same.

In general, non-oriented electrical steel sheet is used for the iron core material in rotating equipment such as motors, generators, and stationary equipment such as small transformers that convert electrical energy into mechanical energy. The magnetic properties of non-oriented electrical steel have iron loss and magnetic flux density, and the lower the iron loss, the better the energy loss. The higher the magnetic flux density, the greater the magnetic field can be induced with the same energy. Since a current may be applied, copper loss can be reduced, so the higher the better.

Generally, in order to improve iron loss and magnetic flux density, which are important magnetic properties of non-oriented electrical steel sheets, alloying elements having high resistivity such as Si, Al, and Mn and segregation such as expensive Sn and Se are mostly used. There is a problem that unit prices rise, so new measures are needed.

On the other hand, Patent Document 1 limits the range of Si, Al and Mn that can be rolled while sufficiently increasing the specific resistance of the electrical steel sheet, and the appropriate range of P, Sn, Sb, Mo, C, S, N, Ti and Nb addition amount and By providing the ratio, a non-oriented electrical steel sheet having excellent high-frequency magnetism and a method for manufacturing the same are provided. Patent Document 2 utilizes the relationship between aluminum (Al) and sulfur (S) components to efficiently arrange an assembly structure advantageous for magnetism. By introducing an improved non-oriented electrical steel sheet and its manufacturing method by the magnetism, there is a limitation in manufacturing a hot-rolled electrical steel sheet as a manufacturing method in the existing hot-milling process.

Korean Unexamined Patent Publication No. 2014-0062225 Korean Unexamined Patent Publication No. 2015-0149426

One aspect of the present invention is to provide a thin non-oriented electrical steel sheet excellent in magnetic properties and shape and a method of manufacturing the same.

The problem of the present invention is not limited to the above description. Anyone of ordinary skill in the art will have no difficulty understanding the additional subject matter of the present invention from the general contents of the present specification.

One embodiment of the present invention is by weight, C: 0.0005 to 0.010%, Si: 0.2 to 2.5%, Al: 0.03 to 1.0%, Mn: 0.03 to 1.5%, P: 0.002 to 0.10%, S: 0.0002 to 0.01%, Sn: 0.0005 ~ 0.1%, Ca: 0.0005 ~ 0.01%, N: 0.0005 ~ 0.010%, balance Fe and other unavoidable impurities, the average grain size of ferrite is 20 ~ 100㎛, width direction of strip It provides a thin non-oriented electrical steel sheet excellent in magnetic properties and shape that the thickness deviation Δt _CR satisfy the following relation 1.

[Relationship 1] Δt _CR / 1-0.03S + 11t ≤ 1.6

(Where Δt _CR is the thickness variation in the width direction of the strip (μm), S is the thickness measurement position (mm) at a point away from the strip width direction edge, and t means the thickness of the strip (mm)). )

Another embodiment of the present invention is in weight%, C: 0.0005 to 0.010%, Si: 0.2 to 2.5%, Al: 0.03 to 1.0%, Mn: 0.03 to 1.5%, P: 0.002 to 0.10%, S: 0.0002 to Continuous casting of molten steel containing 0.01%, Sn: 0.0005 to 0.1%, Ca: 0.0005 to 0.01%, N: 0.0005 to 0.010%, balance Fe and other unavoidable impurities to obtain a thin slab; Roughly rolling the thin slab to obtain a bar having a thickness of 10 to 25 mm; Heating the bar to 1000-1200 ° C .; Hot-rolled the heated bar, in the first rolling mill is carried out at a rolling reduction rate of 40 ~ 75% at 800 ℃ ~ Ar ₁ in the first rolling mill, hot rolled by rolling at 650 ℃ ~ Ar ₁ -100 ℃ in the last rolling mill Obtaining a steel sheet; And winding the hot rolled steel sheet at 500 to 650 ° C., wherein each step is performed continuously, and cold rolling the wound hot rolled steel sheet at a cold reduction rate of 50 to 80% to obtain a cold rolled steel sheet. And recrystallizing annealing the cold rolled steel sheet at 750 ° C. to 950 ° C., wherein the temperature variation in the first rolling mill during the hot finish rolling is 60 ° C. or less, and provides a method of manufacturing a thin non-oriented electrical steel sheet having excellent magnetic properties and shape. do.

According to one aspect of the present invention, it is possible to produce a hot rolled electrical steel sheet having a good shape quality while the thin through the high-speed casting and continuous rolling process in the performance-rolling direct connection process.

In addition, when producing a product of the same final thickness through the production of the thin hot rolled electrical steel sheet can reduce the cold reduction rate compared with the existing hot rolling process, it has a high magnetic flux density, compared to the conventional electrical steel sheet, and excellent magnetic properties with low iron loss It is possible to manufacture a high efficiency non-oriented electrical steel sheet having.

In addition, through the production of the hot-rolled steel sheet, it is possible to manufacture an ultra-thin electrical steel sheet having a thickness of 0.50 mm or less, thereby improving the product production width. In addition, by improving the magnetic properties due to the effect of the museum can be added less expensive ferroalloy such as Sn, reducing the manufacturing cost is advantageous in price competitiveness.

In addition, the thin slab playing method can be used to melt the scrap steel, such as scrap iron in the electric furnace can increase the recycling of resources.

1 is a schematic diagram of equipment for a performance-rolling direct connection process applicable to the present invention.
Figure 2 is another schematic diagram of the installation for the performance-rolling direct connection process applicable to the present invention.
Figure 3 is a result showing the longitudinal thickness crown profile (Profile) of Inventive Example 1 (hot rolled steel sheet) according to an embodiment of the present invention.
Figure 4 is a result showing the longitudinal thickness crown profile (Profile) of the prior art example 1 (hot rolled steel sheet) according to an embodiment of the present invention.
Figure 5 shows the cross-sectional optical microscope structure and the EBSD crystal orientation mapping (Mapping) results of Inventive Examples 1 to 4 (hot-rolled steel sheet) according to an embodiment of the present invention.
6 is a result showing the high temperature tensile strength change according to the temperature of Inventive Example 1 according to an embodiment of the present invention.
Fig. 7 is a schematic diagram showing thickness measurement positions and width direction thickness deviations at a distance apart from the strip width direction edges.
It is a schematic diagram explaining the width | variety thickness deviation of a strip.
9 is a result of examining the correlation between the width direction deviation in the width direction and the width direction variation in the invention example, the comparative example and the prior art example.

Hereinafter, the present invention will be described.

The inventors of the present invention have found that there is a problem that the magnetic flux density of the electrical steel sheet decreases and the iron loss increases when the rolling reduction rate increases during cold rolling. In order to cope with this problem, it is conceivable to improve the magnetic flux density and iron loss at the same time by reducing the thickness of hot rolled material and reducing the cold reduction rate during cold rolling, but it is very difficult to apply due to various operating variables in actual production.

That is, in a typical rolling process, slabs having a thickness of 200 mm or more are produced through low-speed casting, and the slabs produced in this way are reheated in a heating furnace, and then hot rolled in batch form in units of sheets. Decrease. In the case of batch rolling of this type, the top part is introduced into the rolling mill and the tail part has to exit the rolling mill for each slab, so operation accidents frequently occur, which is a limitation in manufacturing an electrical steel sheet having excellent shape and shape. There is.

The inventors of the present invention focus on the fact that in the production of electrical steel sheet, so-called thin slab manufacturing process (mini-mill process), in particular, continuous casting (casting) ~ rolling direct connection process can solve the problems of such electrical steel sheet manufacturing The present invention has been reached.

That is, the performance-rolling direct connection process is excellent in material deviation because the temperature deviation in the width and length direction of the strip is small due to the process characteristics of constant velocity isothermal. In addition, unlike the existing process of finishing and rolling in a batch form for every slab or bar, in the case of a performance-rolling direct connection process, when only the top of the first slab or bar is drawn between the roll and the roll of the rolling mill, The possibility of problems with fishing accidents related to the introduction of slabs or bars can be significantly reduced. In addition, since the product is produced through isothermal isothermal rolling, it has been judged to be a suitable process for manufacturing hot rolled electrical steel sheets because it has the advantages of excellent thickness and width dimensional accuracy compared to existing batch materials and a small plate crown deviation. .

In addition, the electrical steel sheet produced by the performance-rolling direct connection process as described above shows excellent performance in terms of internal materials as compared with the electrical steel sheet manufactured by the conventional batch rolling method.

Hereinafter, the electrical steel sheet of the present invention and a manufacturing method thereof will be described in detail.

 First, the alloy composition of the electrical steel sheet of the present invention will be described. The alloy compositions described below are based on weight percent, unless otherwise specified.

C: 0.0005 ~ 0.010%

Since carbon (C) deteriorates iron loss, the smaller it is, the better. It is preferable that C be in the range of 0.010% or less in that C increases the iron loss considerably when it exceeds 0.010%. Since the said C is small, it is so preferable that there is no restriction | limiting in particular, but considering the decarburization cost, it is preferable to control the minimum to 0.0005%. Therefore, it is preferable that C content is 0.0005 to 0.010%. As for said C, it is more preferable that it is 0.0007 to 0.0050%, and it is still more preferable that it is 0.0010 to 0.0040%.

Si: 0.2-2.5%

Silicon (Si) is generally added as a steel deoxidizer, but is an important element in electrical steel sheets because it has an effect of increasing electrical resistance and reducing iron loss at high frequencies, and in order to obtain such effects, addition of 0.2% or more is required. . However, if it exceeds 2.5%, cracks will be generated during cold rolling, and in addition to deterioration in manufacturability, the magnetic flux density will also decrease, so the upper limit is made 2.5%. Therefore, it is preferable that the said Si content is 0.2 to 2.5%, It is more preferable that it is 0.5 to 2.0%, It is still more preferable that it is 0.8 to 1.6%.

Al: 0.03-1.0%

Aluminum (Al) is generally used as a steel deoxidizer similarly to Si, and an addition of 0.03% or more is preferable because it is an element having a large effect of increasing electrical resistance and reducing iron loss. However, if the content exceeds 1.0%, the casting flux may be picked up during the continuous casting, and thus the physical properties of the mold flux may be changed to prevent lubrication and casting interruption may occur. The Al content is preferably 0.03% to 1.0%, more preferably 0.05% to 0.8%, and even more preferably 0.1% to 0.6%.

Mn: 0.03-1.5%

Manganese (Mn) is an element that can lower the iron loss by increasing the specific resistance in steel, so it is preferable to add 0.03% or more. However, if the content exceeds 1.5%, coarse MnS precipitates are formed in combination with steel S, and not only form austenite phase in the annealing temperature range of the present invention, but also have difficulty in grain coarsening for reducing iron loss. Therefore, it is preferable that said Mn has a range of 0.03-1.5%, It is more preferable that it is 0.05-1.2%, It is still more preferable that it is 0.1-0.8%.

P: 0.002 ~ 0.10%

Phosphorus (P) is an element that can lower the iron loss by increasing the specific resistance in steel, and is an element that can improve the magnetic flux density when added to a magnetic material, and it is preferable to add 0.002% or more for the above effect. However, if it exceeds 0.10%, there is a disadvantage in that the presence of segregation element that attracts the rolling plate break in the ferrite grain boundary when rolling at room temperature greatly weakens the bonding force between the grain boundaries. Therefore, the content of P is preferably in the range of 0.002 to 0.10%, more preferably 0.004 to 0.06%, even more preferably 0.006 to 0.04%.

S: 0.0002 ~ 0.01%

Sulfur (S) forms precipitates and inclusions and deteriorates the magnetic properties of the product. If S exceeds 0.01%, iron loss increases due to precipitation of MnS. However, in order to suppress the cost increase by desulfurization, it is preferable that a minimum is 0.0002%. Therefore, the content of S is preferably in the range of 0.0002 to 0.01%, more preferably 0.0003 to 0.005%, even more preferably 0.0005 to 0.003%.

Sn: 0.0005 ~ 0.1%

Tin (Sn) is an element that segregates at grain boundaries, but the effect on segregation of P is small, and rather, it has an effect of promoting the formation of strain bands in the particles and increasing the magnetic flux density. For the above effect, it is preferable to add 0.0005% or more. However, when exceeding 0.1%, steel will embrittle and surface defects, such as plate breaking and peeling, in the manufacturing process will increase. Therefore, the Sn content is preferably in the range of 0.0005 to 0.1%, more preferably 0.001 to 0.06%, even more preferably 0.002 to 0.04%, most preferably 0.002 to 0.02%.

Ca: 0.0005 ~ 0.01%

Calcium (Ca) is an element that reacts with Al and O in molten steel to form spherical inclusions (12CaO.17Al ₂ O ₃ ) with a low melting point to facilitate nozzle clogging and inclusion separation injury. If the Ca content is less than 0.0005% it is difficult to secure the effect. However, if it exceeds 0.01%, it may adversely affect iron loss by forming oxides in steel. Therefore, the Ca content is preferably in the range of 0.0005 to 0.01%, more preferably 0.001 to 0.008%, and even more preferably 0.002 to 0.005%.

N: 0.0005 ~ 0.010%

Nitrogen (N) preferably has a range of 0.010% or less because it deteriorates magnetic properties similarly to C described above. Since there are few said N, it is so preferable that there is no restriction | limiting in particular, but considering the denitrification cost, it is preferable to control the minimum to 0.0005%. Therefore, the content of N is preferably 0.0005 to 0.010%, more preferably 0.001 to 0.008, and even more preferably 0.002 to 0.006%.

The remaining component of the present invention is iron (Fe). However, in the conventional manufacturing process, impurities which are not intended from the raw material or the surrounding environment may be inevitably mixed, and thus cannot be excluded. Since these impurities are known to those skilled in the art, all of them are not specifically mentioned in the present specification.

On the other hand, the electrical steel sheet of the present invention is selected from the group consisting of Nb, V, Ti, Mo, Cu, Ni, Cr, Zn, Se, Sb, Zr, W, Ga, Ge and Mg in addition to the alloy composition described above. One or more types can be included so that the sum may be 0.2 weight% or less. The tramp element is an impurity element derived from scrap used as a raw material in the steelmaking process, ladle and tundish refractory, etc., and when the sum exceeds 0.2%, it is liquefied at high temperature to deteriorate playability or As a result, precipitates may form and worsen the magnetism.

On the other hand, the microstructure of the non-oriented electrical steel sheet of the present invention is more than 95% ferrite in the area fraction; And at least one member selected from the group consisting of pearlite, precipitates and inclusions in a range of 5% or less in total. When the area fraction of the ferrite is less than 95%, the fraction of pearlite, precipitates and inclusions is relatively high, so that the magnetic properties may be deteriorated even after annealing after cold rolling. The fraction of ferrite is more preferably 97% or more, and even more preferably 98% or more. The precipitate may be a single or complex carbonitride composed of Ti, Nb, V, Mo, and C, N, and may include a single or complex sulfide such as CaS, MnS, CuS, and MgS. In addition, the individual may include single or complex inclusions such as Al, Si, Ca, Nb, V, Ti, Mo, Cu, Cr, Ni, Zn, Se, Sb, Zr, W, Ga, Ge, and Mg. Can be.

At this time, the average grain size of the ferrite is preferably in the range of 20 ~ 100㎛ in equivalent diameter. If the average grain size of the ferrite is less than 20㎛ the crystals do not grow enough to deteriorate the magnetism, if it exceeds 100㎛ the magnetic flux density can be lowered, the average size of the ferrite grain is 20 ~ 100 in the equivalent diameter It is preferable to control by micrometer, It is more preferable that it is 20-80 micrometers, It is still more preferable that it is 20-60 micrometers.

On the other hand, in the non-oriented electrical steel sheet of the present invention, it is preferable that the thickness variation Δt _CR of the strip satisfies the following relational formula (1). If the following relation 1 is satisfied, excellent appearance shape quality can be ensured. On the other hand, the smaller the value of the relational expression 1 can ensure a better appearance shape quality.

[Relationship 1] Δt _CR / 1-0.03S + 11t ≤ 1.6

(Where Δt _CR is the thickness variation in the width direction of the strip (μm), S is the thickness measurement position (mm) at a point away from the strip width direction edge, and t means the thickness of the strip (mm)). )

The thickness of the non-oriented electrical steel sheet provided by the present invention is preferably 0.15 ~ 0.50mm. When the thickness is less than 0.15 mm, productivity is reduced, and when the thickness exceeds 0.5 mm, the effect of reducing iron loss may be small.

Electrical steel sheet of the present invention provided as described above may have a magnetic flux density (B50) of 1.71 ~ 1.75T, iron loss (W15 / 50) of 4.0 ~ 5.3W / kg. The magnetic flux density (B50, T) is the magnetic flux density induced in the magnetic field of 5000 A / m, and the iron loss (W15 / 50) is the average of the rolling direction and the perpendicular direction when the magnetic flux density of 1.5 Tesla is induced at the 50 Hz frequency. Loss (W / kg). The higher the magnetic flux density is better, but in order to secure more than 1.75, an additional segregation element must be added. As a result, the manufacturing cost may increase, and if the magnetic flux density is less than 1.71, sufficient magnetic properties cannot be obtained. Can be In addition, the lower the iron loss is better, but in order to control less than 4.0W / kg, an additional element to increase the specific resistance must be added, which can increase the manufacturing cost, if the iron loss exceeds 5.3W / kg This can be a problem in use.

Hereinafter, the non-oriented electrical steel sheet manufacturing method of the present invention will be described.

1 is a schematic diagram of a facility for a performance-rolling direct connection process applicable to the present invention, which is a schematic diagram of a performance-rolling direct connection process equipment applicable to the production of a hot rolled steel sheet of a thin film to obtain a final electrical steel sheet. The thin electrical steel sheet excellent in shape quality according to an embodiment of the present invention may be manufactured from a hot rolled steel sheet produced by applying a performance-rolling direct connection facility as shown in FIG. 1. Performance-rolling direct connection equipment is largely composed of a continuous casting machine 100, rough rolling mill 400, the finishing rolling mill 600. The performance-rolling direct connection facility includes a high speed continuous casting machine 100 producing a thin slab (a) of a first thickness, and rolling the slab into a bar (b) of a second thickness thinner than the first thickness. The rough rolling mill 400, the finishing mill 600 for rolling the bar of the second thickness into a strip (c) of the third thickness, and a winding machine 900 for winding the strip may be included. In addition, rough mill scale breaker 300 (Rough Mill Scale Breaker, hereinafter 'RSB') in front of the roughing mill 400 and finishing mill scale breaker (500) (Fishing Mill Scale Breaker, hereinafter 'in front of the finishing mill 600) FSB ') may be further included, and the surface scale may be easily removed to produce electrical steel sheets having excellent surface quality in a later process. In addition, isothermal isothermal rolling is possible through the direct process of rolling to rolling, so that the steel plate width and longitudinal temperature deviation are very low, and precise cooling control is possible in ROT [Run Out Table (700)] (hereinafter referred to as "runout table"). It is possible to produce thin hot rolled electrical steel sheets with excellent isotropy. The strips thus rolled and cooled are cut by the high speed shears 800 and wound by the winding machine 900 to be produced as products. On the other hand, in front of the finish rolling scale breaker 500 may be provided with a heater 200 for further heating the bar.

Figure 2 is another schematic diagram of the installation for the performance-rolling direct connection process applicable to the present invention. The play-rolling direct connection facility disclosed in FIG. 2 has the same configuration as the facility described in FIG. 1, but is provided with a heater 200 ′ that additionally heats the slab in front of the rough rolling mill 400, thereby easily securing the slab edge temperature. It is possible to reduce the occurrence of edge defects, which is advantageous for securing the surface quality. In addition, a space equal to the length of one or more slabs is secured before rough rolling, and batch rolling is also possible.

The hot rolled electrical steel sheet excellent in magnetic properties and shape of the present invention can be produced in both the performance-rolling direct connection facilities disclosed in FIGS. 1 and 2.

First, molten steel having the alloy composition described above is continuously cast to obtain a thin slab. At this time, the continuous casting is preferably performed at a casting speed of 3.5 ~ 8.5mpm (m / min). The reason why the casting speed is more than 3.5mpm is because the high speed casting and the rolling process are connected, and a certain casting speed is required to secure a target rolling temperature. If the casting speed is less than 3.5mpm, Al increases the pick-up amount in the mold flux, thereby changing the physical properties of the mold flux, thereby reducing the lubrication action, thereby causing the casting stoppage. If it exceeds 8.5mpm, the operation success rate may be reduced due to the instability of the molten steel. Therefore, the casting speed is preferably in the range of 3.5 to 8.5mpm, more preferably in the range of 4.0 to 7.5mpm. It is more preferable to have the range of 4.5-7.0mpm.

The thin slab preferably has a thickness of 60 ~ 130mm. When the thickness of the thin slab exceeds 130mm, not only the high speed casting is difficult, but also the rolling load increases during rough rolling, and when the thickness is less than 60mm, the temperature of the cast slab rapidly occurs, making it difficult to form a uniform structure. In order to solve this problem, it is possible to additionally install a heating device, but this is a factor to improve the production cost, it is desirable to exclude as possible. Therefore, it is preferable to control the thickness of a thin slab to 60-130 mm, It is more preferable that it is 60-120 mm, It is still more preferable that it is 80-110 mm.

The continuous cast thin slab is rough rolled to obtain a bar. At this time, the thickness of the bar is preferably 10 ~ 25mm. When the thickness of the bar exceeds 25mm, in the first rolling mill during the finish rolling, the rolling load may increase sharply due to the increase in the reduction ratio, so that the thickness variation in the strip width direction may be increased. It may cause difficulty in, and it is difficult to secure the temperature during finish rolling.

On the other hand, the entrance temperature during the rough rolling may be 1000 ~ 1200 ℃. When the rough rolling entrance temperature is less than 1000 ° C., the rough rolling load may increase and cracks may occur at the edge portion of the bar. On the other hand, if the temperature exceeds 1200 ° C., the hot rolled scale may remain to degrade the hot rolled surface quality.

The exit temperature during the rough rolling may be 900 ° C. or more. If the temperature is less than 900 ° C, it is difficult to secure the finish rolling temperature.

The rolling speed during the rough rolling may be 20 ~ 50mpm. If the rolling speed is greater than 50mpm during rough rolling, the performance-rolling success rate is lowered because the performance-rolling is directly connected and a problem occurs in the playing process. On the other hand, if less than 20mpm it is difficult to secure the temperature during the finish rolling, it is difficult to produce a rolling load and obtain a uniform structure.

Then the bar is heated to 1000 ~ 1200 ℃. The reason for controlling the heating temperature of the bar is to stably produce the hot rolled electrical steel sheet and to secure the surface quality. If the temperature is less than 1000 ° C, the exit temperature of the finish rolling is lowered and the rolling load increases rapidly, resulting in poor sheet flow. As a result, plate breaking may occur. If the temperature exceeds 1200 ° C., excessive scale may be generated and surface quality may be degraded.

Thereafter, the heated bar is hot-finish-rolled, and the hot-rolling is rolled at a rolling reduction ratio of 40 to 75% at 800 ° C to Ar ₁ in the first rolling mill, and at 650 ° C to Ar ₁ -100 ° C in the final rolling mill. To obtain a hot rolled steel sheet. At this time, it is preferable to perform rolling when the microstructure of the bar is a ferrite single phase in the first rolling mill and the last rolling mill during the hot finishing rolling.

The Ar ₁ is a temperature at which the austenite structure is transformed into a ferrite structure upon cooling, and can be calculated through the following relational formula 2.

Ar ₁ (° C) = 873-14163C + 107Si + 178Al-154Mn-175P-199S-388Ti + 9683N

(C, Si, Al, Mn, P, S, Ti, N in the relation 2 respectively means the content (wt%) of the element.)

The hot finish rolling may be performed in a finish rolling mill consisting of three to six stands of the bar made in the rough mill. Since the rolling temperature between the stands in the finishing rolling mill greatly affects the rolling load fluctuations and the plateability due to the phase transformation, precise control is required.

Rolling in the finish rolling when the first rolling mill is preferably carried out in 800 ℃ ~ Ar _1. When Ar ₁ is exceeded, austenite transformation occurs and pressure load fluctuates severely, and plate breakage may occur due to poor flowability. Although the rolling in the first rolling mill during finish rolling may be performed at less than 800 ° C, in this case, the temperature is too low in the last rolling mill, and the pressure load is rapidly increased, which may cause plate breakage due to poor boardability. Thus, rolling in the first rolling mill during finish rolling is preferably carried out at a temperature of 800 ℃ ~ Ar _1.

At this time, the rolling reduction in the first rolling mill during the finish rolling is preferably 40 to 75%. When the rolling reduction rate in the first rolling mill exceeds 75% during the finish rolling, the rolling load may increase sharply and the thickness variation of the strip may be increased, and plate breakage may occur due to poor sheet flow. On the other hand, if less than 40%, there may be a difficulty in manufacturing a thin electrical steel sheet due to the increased rolling load because the reduction ratio in the last rolling mill increases.

It is preferable to perform rolling in the last rolling mill at the time of the said finish rolling in the temperature range of 650 degreeC-Ar1-100 degreeC. If Ar ₁ -100 ℃ is exceeded, austenite transformation occurs and high temperature strength fluctuates, resulting in poor platelet flow rate, leading to high risk of plate breakage. Leaf breaking may occur. Thus, rolling in the finish rolling at the time of the last rolling mill is preferably performed at a temperature of 650 ℃ ~ Ar ₁ -100 ℃. In addition, in the production of one strip during the finish hot rolling, the first rolling mill side temperature deviation is preferably controlled to 60 ° C. or less, more preferably 50 ° C. or less. If the temperature variation of the first rolling mill exceeds 60 ° C, the thickness variation of the product may be severe.

The hot rolled steel sheet is wound at 500 to 650 ° C. If the winding temperature is less than 500 ℃, the grain size is too small, the crystal grains do not grow enough even after annealing, so that the iron loss can increase as the hysteresis loss increases, and when the temperature is over 650 ℃, fine precipitates are increased and the magnetic properties are increased. This can be degraded.

In the hot rolled steel sheet obtained through the rolling process as described above, the area fraction of the recrystallized texture composed of {110} based on the thickness direction cross section is preferably 50% or more. As recrystallization increases, it becomes easier to secure a uniform structure after homogenization and annealing, and the magnetic properties are improved. Therefore, when the recrystallization structure is less than 50%, the above-described effect is insufficient, so that the recrystallized texture composed of {110} based on the thickness direction cross section of the hot rolled electrical steel sheet is preferably 50% or more.

In addition, the hot rolled steel sheet is preferably 2.3mm or less in thickness. As the thickness of the hot rolled steel sheet decreases, the recrystallized texture increases, thereby obtaining a uniform structure after annealing, and reducing the cold rolling rate, thereby improving magnetic properties. It may not be enough. Therefore, the thickness of the hot rolled electrical steel sheet is preferably 2.3mm or less. The thickness of the hot rolled electrical steel sheet is more preferably 2.0 mm or less, still more preferably 1.6 mm or less, and most preferably 1.4 mm or less.

In addition, the hot rolled steel sheet preferably has a longitudinal thickness variation (crown, crown) of 30 μm or less. The longitudinal thickness variation is examined in the longitudinal direction for the difference between the thickness of the center portion in the width direction of the strip and the thickness of the edge (Edge) to 25 mm point. If the thickness exceeds 30㎛, cold rolling cannot be performed due to poor thickness, and this part must be cut in order to perform cold-rolling, and this may result in a sharp drop in the real rate, so that the thickness variation of the hot rolled electrical steel sheet is 30㎛. It is preferable to control below. It is more preferable that it is 20 micrometers, and, as for the longitudinal thickness variation of the said hot rolled electrical steel sheet, it is still more preferable that it is 15 micrometers.

On the other hand, the method for producing a hot rolled steel sheet described above is a continuous rolling mode used in the play-rolling direct connection process, characterized in that each of the above-described process is carried out continuously.

Thereafter, the wound hot rolled steel sheet is cold rolled to obtain a cold rolled steel sheet. The cold rolling reduction rate is preferably in the range of 50% to 80%. If the rolling reduction rate is less than 50% during cold rolling, the reduction ratio is too small to sufficiently recrystallize. If the reduction ratio is more than 80%, the reduction ratio is high and the grains become too fine. This can be a lot.

On the other hand, before the cold rolling may further include a step of removing the oxide layer by pickling the hot rolled steel sheet. At this time, pickling can be carried out under ordinary conditions, and the pickling treatment which can be used in the present invention is not particularly limited, as long as all of the treatment methods used in the electrical steel sheet pickling process are applicable.

Thereafter, the cold rolled steel sheet is subjected to final recrystallization annealing at 750 to 950 ° C. If the final recrystallization annealing temperature is less than 750 ℃ recrystallization does not occur sufficiently, if the final recrystallization annealing temperature exceeds 950 ℃ because the rapid growth of crystal grains occurs, the magnetic flux density is lowered, high frequency iron loss is increased, the final recrystallization annealing It is preferable that temperature is 750-950 degreeC.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, it is necessary to note that the following examples are only for illustrating the present invention in more detail, and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the claims and the matters reasonably inferred therefrom.

(Example 1)

After preparing the molten steel having the alloy composition of the following Table 1, by applying a performance-rolling direct connection process to continuously cast the molten steel at a casting speed of 6.0mpm to obtain a 90mm thick slab, the thin slab was prepared in Table 2 Hot rolled steel sheet (Hot Rolled, hereinafter HR) was prepared under the conditions, and the hot rolled steel sheet was cold rolled and annealed under the conditions shown in Table 2 to prepare a final product. In addition, in the conventional example 1, after casting a slab having a thickness of 250 mm in the existing hot rolling, a hot rolled steel sheet having a thickness of 2.3 mm was manufactured in an existing batch process under the manufacturing conditions shown in Table 2 below, and cold rolled at a rolling reduction of 78%. After annealing, a final product having a thickness of 0.50 mm was produced.

For the invention examples, comparative examples and conventional examples prepared as described above, after measuring the plate breakage, longitudinal thickness variation (crown), microstructure and magnetic properties, and the like are shown in Table 3 below.

Microstructures at the finish rolling inlet and outlet temperatures were predicted using thermodynamic software Thermo-Calc (DATABASE: TCFE6). In addition, Ar ₁ represented by the following Equation 2 was obtained using Thermo-Calc in a given composition range, and a regression equation was derived through correlation between the compositional component and temperature using Minitab, which is a statistical program.

Ar ₁ (° C) = 873-14163C + 107Si + 178Al-154Mn-175P-199S-388Ti + 9683N

The longitudinal thickness variation of the strip was examined in the longitudinal direction for the difference between the thickness of the central portion in the width direction of the strip and the thickness between the edges and edges of 25 mm.

Ferrite fraction, {110} texture fraction, and final product ferrite grain size of HR materials were measured using an optical microscope and EBSD (Electron Backscatter Diffraction).

The magnetic properties of magnetic flux density and iron loss were measured by cutting at least three specimens of 60mm * 60mm for each specimen and measuring the magnetic properties in the rolling and vertical directions with a single sheet tester, and averaging the measured values in both directions. It is shown. At this time, B50 is the magnetic flux density induced in the magnetic field of 5000A / m, iron loss (W15 / 50) is the average loss in the rolling direction and the perpendicular direction (W / kg) when the magnetic flux density of 1.5 Tesla at 50 Hz frequency is induced ).

division Steel grade Alloy element (wt%) C Si Al Mn P S Sn Ca N Inventive Steel 1 A 0.0030 1.09 0.25 0.25 0.010 0.0010 0.0050 0.0023 0.0030 Inventive Steel 2 B 0.0031 1.05 0.24 0.25 0.011 0.0009 0.0030 0.0025 0.0031 Invention Steel 3 C 0.0031 1.06 0.25 0.25 0.010 0.0011 0.0036 0.0031 0.0030 Conventional Steel D 0.0022 1.25 0.29 0.25 0.010 0.0024 0.0300 0.0010 0.0025

division Steel grade Hot rolled
Grater
thickness
(mm) Relation
2 Bar
Heating temperature
(℃) Rolling temperature at the first rolling mill during hot finish rolling
(℃) Rolling temperature at the last mill during hot finish rolling
(℃) final
product
thickness
(mm) Cold
Rolling reduction
(%) Annealed
Temperature
(℃) Inventive Example 1 A 1.20 980 1156 935 775 0.50 58 830 Inventive Example 2 1.40 1157 940 771 0.50 64 832 Inventive Example 3 1.60 1155 935 769 0.50 69 834 Inventive Example 4 1.80 1158 941 770 0.50 72 835 Inventive Example 5 2.00 1150 938 771 0.50 75 832 Inventive Example 6 B 1.20 974 1155 931 771 0.50 58 832 Inventive Example 7 1.20 1168 935 775 0.35 71 835 Inventive Example 8 1.40 1154 935 772 0.50 64 834 Inventive Example 9 1.40 1153 937 776 0.35 75 836 Inventive Example 10 1.60 1156 936 770 0.50 69 830 Inventive Example 11 1.80 1150 937 769 0.50 72 835 Inventive Example 12 2.00 1151 934 768 0.50 75 830 Comparative Example 1 2.50 1159 935 765 0.50 85 832 Inventive Example 13 C 1.20 976 1150 936 770 0.50 58 835 Comparative Example 2 1.20 1166 985 771 - - - Comparative Example 3 1.20 1175 998 772 - - - Comparative Example 4 1.20 980 825 639 - - - Comparative Example 5 1.20 995 840 648 - - - Comparative Example 6 1.20 1150 940 778 0.50 58 745 Inventive Example 14 1.20 1155 941 785 0.50 58 870 Inventive Example 15 1.20 1157 935 786 0.50 58 900 Inventive Example 16 1.20 1152 936 782 0.50 58 940 Inventive Example 17 1.10 1155 937 782 0.50 55 835 Comparative Example 7 0.95 1150 935 771 0.50 47 832 Inventive Example 18 0.95 1152 936 775 0.35 63 835 Inventive Example 19 0.95 1162 939 776 0.27 72 831 Conventional Example 1 D 2.50 1011 1200 1100 900 0.50 85 830 Ar ₁ (° C) = 873-14163C + 107Si + 178Al-154Mn-175P-199S-388Ti + 9683N

division Steel grade Hot rolled steel Final product Finish rolling
Organization at the entrance Finish rolling
Organization at the exit Plate breaking
The presence or absence Length
direction
thickness
Deviation
(Μm) Ferra
ITE
Fraction
(area%) {110}
set
group
Area ratio
(%) Magnetic flux
density
(B50, T) Iron loss
(W15 / 50,
W / kg) Ferra
ITE
Grain
size
(Μm) Inventive Example 1 A F F × 5 98 81 1.724 4.78 37 Inventive Example 2 F F × 6 98 75 1.721 4.87 35 Inventive Example 3 F F × 6 98 71 1.719 4.92 33 Inventive Example 4 F F × 7 98 63 1.718 4.95 36 Inventive Example 5 F F × 8 98 56 1.715 5.10 29 Inventive Example 6 B F F × 6 98 80 1.724 4.79 38 Inventive Example 7 F F × 6 98 81 1.710 4.63 39 Inventive Example 8 F F × 6 98 76 1.722 4.86 35 Inventive Example 9 F F × 5 98 79 1.711 4.72 37 Inventive Example 10 F F × 7 98 72 1.720 4.93 33 Inventive Example 11 F F × 6 98 64 1.719 4.95 31 Inventive Example 12 F F × 9 98 55 1.716 5.11 29 Comparative Example 1 F F × 13 98 47 1.702 5.32 19 Inventive Example 13 C F F × 5 98 80 1.719 4.79 36 Comparative Example 2 F + A F ○ Cold rolled / annealed due to plate breaking Comparative Example 3 F + A F ○ Cold rolled / annealed due to plate breaking Comparative Example 4 F F ○ Cold rolled / annealed due to plate breaking Comparative Example 5 F F ○ Cold rolled / annealed due to plate breaking Comparative Example 6 F F × 6 98 81 1.692 5.30 18 Inventive Example 14 F F × 7 98 82 1.725 4.35 40 Inventive Example 15 F F × 6 98 81 1.735 4.18 47 Inventive Example 16 F F × 8 98 82 1.736 4.09 49 Inventive Example 17 F F × 5 98 84 1.729 4.72 34 Comparative Example 7 F F × 4 98 86 1.701 5.35 19 Inventive Example 18 F F × 5 98 86 1.722 4.62 31 Inventive Example 19 F F × 5 98 87 1.720 4.57 32 Conventional Example 1 D A F × 35 98 53 1.711 5.15 25  Where F stands for Ferrite and A stands for Austenite.

As can be seen from Tables 1 to 3, Inventive Examples 1 to 19 satisfying both the alloy composition and the manufacturing conditions proposed in the present invention are the target longitudinal thickness (crown) deviation, microstructure fraction / grain size and magnetic It can be seen that all of the properties, and despite the low Sn content compared to the conventional example 1, it can be seen that the magnetic properties are excellent due to the reduction of the cold reduction rate according to the hot-rolled.

Figure 3 is a result showing the longitudinal thickness crown profile (Profile) of the invention example 1 (hot rolled steel), Figure 4 is the length of the conventional example 1 (hot rolled steel) manufactured by using a batch mode in the conventional hot-milling This is the result of directional thickness crown profile. As can be seen from Figure 3, the hot rolled electrical steel sheet produced in continuous continuous rolling mode in the performance-rolling direct connection process is excellent in thickness crown profile compared to the electrical steel sheet produced in batch mode in the existing hot rolling, the error rate is also excellent. This is because hot rolled steel sheet manufactured by conventional hot rolling has to cut a large portion of the thickness crown.

FIG. 5 shows cross-sectional optical microscope structures and EBSD crystal orientation mapping results of Inventive Examples 1 to 4 (hot-rolled steel sheets). As the thickness of the hot-rolled steel sheet becomes thinner, {110} textures recrystallized near the surface layer. Able to know.

6 is a result showing the change in high temperature tensile strength according to the temperature of Inventive Example 1. As can be seen from Figure 6, the change in strength is severe due to the phase transformation of ferrite and austenite at the temperature of Ar ₁ ~ Ar ₃ , it can be seen that the pearlite transformation occurs rapidly below 650 ℃. Therefore, it is suggested that precise temperature control is required during finish rolling in order to manufacture thin hot rolled steel sheet.

On the other hand, Comparative Example 1 does not satisfy the {110} texture fraction and the cold reduction rate of the hot rolled steel proposed in the present invention, it can be seen that the magnetic properties are inferior due to insufficient grain growth after annealing.

Comparative Examples 2 and 3 did not satisfy the heating temperature of the bar and had a two-phase structure of austenite (A) and ferrite (F) at the finish rolling side temperature, so that the strength was severely changed, causing plate breakage due to poor flowability. .

Comparative Examples 4 and 5 did not satisfy the heating temperature and the rolling temperature in the final rolling mill during the hot finishing rolling proposed in the present invention, so that the rolling load rapidly increased and plate breakage occurred due to poor plateability.

Comparative Example 6 does not satisfy the annealing temperature proposed in the present invention can be seen that the recrystallization does not occur sufficiently that the magnetic properties are low.

Comparative Example 7 can not be satisfied with the cold reduction rate proposed in the present invention it can be seen that the recrystallization does not occur sufficiently after the annealing is low magnetic properties.

(Example 2)

Hot rolled material (HR material) and final product (CR material) according to bar thickness, first rolling mill side temperature variation, first rolling mill rolling rate, and final product thickness for inventive steel 1 and conventional steel of Example 1 The correlation with the width direction deviation of (Crown, Δt _CR (μm)) was examined, and the results are shown in Tables 4 and 5 below. At this time, as shown in Figure 7 after measuring the thickness variation in the thickness measurement position [eg: edge ~ 25mm, edge ~ 50mm, etc.] a distance away from the strip width direction edge of the hot rolled material and the final product, the following table 5 is shown. Fig. 7 is a schematic diagram showing thickness measurement positions and width direction thickness deviations at a distance apart from the strip width direction edges. The thickness deviation in the width direction means a difference between the thickness of the central portion C _t of the width direction of the strip and the thickness average [(E1x _t + E2x _t ) / 2] of both edges, as shown in FIG. 8. It means that the appearance shape quality of the strip is excellent. In addition, the thickness variation of the hot rolled material and the final product means an average value of the top and the tail. It is a schematic diagram explaining the width | variety thickness deviation of a strip.

division Steel grade bar
thickness
(mm) Hot rolled
Grater
thickness
(mm) Finish rolling final
product
thickness
(mm) First Rolling Mill
Temperature range (℃) First Rolling Mill
Rolling reduction (%) First Rolling Mill
Rolling load deviation (ton) Inventive Example 20 A 15 1.4 25 58 45 0.50 Inventive Example 21 0.35 Inventive Example 22 0.27 Inventive Example 23 16 1.6 30 60 50 0.50 Inventive Example 24 0.35 Inventive Example 25 0.27 Inventive Example 26 17 1.8 35 62 55 0.50 Inventive Example 27 0.35 Inventive Example 28 0.27 Inventive Example 29 18 2.0 25 62 65 0.50 Inventive Example 30 0.35 Inventive Example 31 0.27 Comparative Example 8 16 1.4 90 58 150 0.50 Comparative Example 9 0.35 Comparative Example 10 0.27 Comparative Example 11 18 1.4 25 78 80 0.50 Comparative Example 12 0.35 Comparative Example 13 0.27 Comparative Example 14 26 1.4 25 88 95 0.50 Comparative Example 15 0.35 Comparative Example 16 0.27 Conventional Example 2 D 16 2.5 100 54 800 0.50 Conventional Example 3 0.35 Conventional Example 4 0.27

division Hot rolled material Final product Relationship 1 Width direction thickness deviation (㎛) Width direction thickness deviation (㎛) 25 mm 50 mm 75 mm 100 mm 25 mm 50 mm 75 mm 100 mm 25 mm 50 mm 75 mm 100 mm Inventive Example 20 36 25 18 14 5.9 4.8 3.9 3.0 1.0 1.0 0.9 0.9 Inventive Example 21 4.3 3.2 2.3 2.1 1.0 1.0 0.9 1.1 Inventive Example 22 3.4 2.2 1.5 1.3 1.1 0.9 0.9 1.3 Inventive Example 23 37 24 20 15 6.2 5.0 4.0 3.2 1.1 1.0 0.9 0.9 Inventive Example 24 4.4 3.6 2.9 2.2 1.1 1.1 1.1 1.2 Inventive Example 25 3.7 2.5 1.9 1.2 1.1 1.0 1.1 1.2 Inventive Example 26 39 28 22 17 6.3 5.1 4.3 3.3 1.1 1.0 1.0 0.9 Inventive Example 27 4.3 3.2 2.6 2.1 1.0 1.0 1.0 1.1 Inventive Example 28 3.8 2.2 1.6 1.1 1.2 0.9 0.9 1.1 Inventive Example 29 42 29 23 18 6.3 5.3 4.5 3.4 1.1 1.1 1.1 1.0 Inventive Example 30 4.6 3.4 2.8 2.5 1.1 1.0 1.1 1.4 Inventive Example 31 4.0 2.6 1.8 1.3 1.2 1.1 1.0 1.3 Comparative Example 8 52 41 36 29 10.6 8.7 7.8 6.8 1.8 1.7 1.8 1.9 Comparative Example 9 9.2 7.0 6.3 5.3 2.2 2.1 2.4 2.9 Comparative Example 10 8.4 6.0 5.0 4.1 2.6 2.4 2.9 4.2 Comparative Example 11 53 40 34 26 10.7 8.6 7.8 6.8 1.9 1.7 1.8 1.9 Comparative Example 12 9.5 7.2 6.0 5.1 2.3 2.1 2.3 2.8 Comparative Example 13 8.4 6.1 5.2 4.2 2.6 2.5 3.0 4.3 Comparative Example 14 53 43 36 30 11.2 8.9 7.6 6.9 1.9 1.8 1.8 2.0 Comparative Example 15 9.3 7.1 6.1 5.2 2.3 2.1 2.3 2.8 Comparative Example 16 8.3 6.1 5.1 4.2 2.6 2.5 6.0 1.3 Conventional Example 2 65 54 48 42 11.8 9.8 8.4 7.8 2.1 2.0 2.0 2.2 Conventional Example 3 10.5 8.6 7.5 6.4 2.6 2.6 2.9 3.5 Conventional Example 4 9.5 7.3 6.0 5.1 3.0 3.0 3.5 5.3 [Relationship 1] Δt _CR / 1-0.03S + 11t ≤ 1.6
(Where Δt _CR is the thickness variation in the width direction of the strip (μm), S is the thickness measurement position (mm) at a point away from the strip width direction edge, and t means the thickness of the strip (mm)). )

As can be seen from Tables 4 and 5, Inventive Examples 20 to 31 satisfying both the relational formula 1 and the manufacturing conditions proposed in the present invention are the thickness deviation of the width direction of the hot rolled material compared to Comparative Examples 8 to 16 and Conventional Examples 2 to 4 Is good, and it can be seen from this that the thickness variation of the final product is also excellent.

9 is a result of examining the correlation between the width direction deviation in the width direction and the width direction variation in the invention examples, comparative examples and conventional examples. As can be seen from Figure 9 it can be seen that the inventive steel (Invention Examples 20 to 31) has a small thickness variation in comparison with the comparative steel (Comparative Examples 8 to 16) and conventional steel (Prior Examples 2 to 4).

a: slab b: bar
c: hot rolled steel sheet
100: continuous casting machine 200, 200 ': heater
300: Roughing Mill Scale Breaker (RSB)
400: roughing mill
500: Finishing Mill Scale Breaker (FSB)
502: coolant jet nozzle
504: coolant
600: finish rolling mill 700: runout table
800: high speed shear 900: winder

Claims (15)

By weight%, C: 0.0005 to 0.010%, Si: 0.2 to 2.5%, Al: 0.03 to 1.0%, Mn: 0.03 to 1.5%, P: 0.002 to 0.10%, S: 0.0002 to 0.01%, Sn: 0.0005 to 0.1%, Ca: 0.0005 ~ 0.01%, N: 0.0005 ~ 0.010%, balance Fe and other unavoidable impurities,
The average grain size of ferrite is 20 to 100 µm,
A thin non-oriented electrical steel sheet having excellent magnetic properties and shapes in which the thickness variation Δt _CR of the strip satisfies the following relational expression 1.
[Relationship 1] Δt _CR / 1-0.03S + 11t ≤ 1.6
(Where Δt _CR is the thickness variation in the width direction of the strip (μm), S is the thickness measurement position (mm) at a point away from the strip width direction edge, and t means the thickness of the strip (mm)). )
The method according to claim 1,
The electrical steel sheet has a total weight of 0.2 or more as one or more selected from the group consisting of Nb, V, Ti, Mo, Cu, Ni, Cr, Zn, Se, Sb, Zr, W, Ga, Ge, and Mg as tramp elements. Non-oriented electrical steel sheet excellent in magnetic properties and shape to be included in the range of% or less.
The method according to claim 1,
The electrical steel sheet is more than 95% ferrite in the area fraction; And a magnetic non-oriented electrical steel sheet having excellent magnetic properties and shapes having a microstructure comprising at least one selected from the group consisting of pearlite, precipitates and inclusions in a range of 5% or less in total.
The method according to claim 1,
The electrical steel sheet is a thin non-oriented electrical steel sheet having excellent magnetic properties and shape having a thickness of 0.15 ~ 0.50mm.
The method according to claim 1,
The electrical steel sheet has a magnetic flux density (B50) of 1.71 ~ 1.75T, iron loss (W15 / 50) of 4.0 ~ 5.3W / kg magnetic non-oriented electrical steel sheet excellent in magnetic properties and shape.
By weight%, C: 0.0005 to 0.010%, Si: 0.2 to 2.5%, Al: 0.03 to 1.0%, Mn: 0.03 to 1.5%, P: 0.002 to 0.10%, S: 0.0002 to 0.01%, Sn: 0.0005 to Continuous casting of molten steel containing 0.1%, Ca: 0.0005 to 0.01%, N: 0.0005 to 0.010%, balance Fe and other unavoidable impurities to obtain a thin slab;
Roughly rolling the thin slab to obtain a bar having a thickness of 10 to 25 mm;
Heating the bar to 1000-1200 ° C .;
Hot-rolled the heated bar, in the first rolling mill is carried out at a rolling reduction rate of 40 ~ 75% at 800 ℃ ~ Ar ₁ in the first rolling mill, hot rolled by rolling at 650 ℃ ~ Ar ₁ -100 ℃ in the last rolling mill Obtaining a steel sheet; And
It comprises the step of winding the hot rolled steel sheet at 500 ~ 650 ℃,
Each of the above steps is carried out continuously,
Cold rolling the wound hot rolled steel sheet at a cold reduction rate of 50 to 80% to obtain a cold rolled steel sheet; And
Re-crystallizing the cold rolled steel sheet at 750 ~ 950 ℃,
The temperature variation in the first rolling mill during the hot finish rolling is a method of manufacturing a thin non-oriented electrical steel sheet having excellent magnetic properties and shape less than 60 ℃.
The method according to claim 6,
The molten steel is 0.2% by weight of one or more selected from the group consisting of Nb, V, Ti, Mo, Cu, Ni, Cr, Zn, Se, Sb, Zr, W, Ga, Ge, and Mg as tramp elements. Method for producing a thin non-oriented electrical steel sheet excellent in magnetic properties and shape included in the following range.
The method according to claim 6,
The continuous casting is a method of manufacturing a thin non-oriented electrical steel sheet having excellent magnetic properties and shape performed at a casting speed of 3.5 ~ 8.5mpm.
The method according to claim 6,
The thin slab is a method of manufacturing a thin non-oriented electrical steel sheet having excellent magnetic properties and shape having a thickness of 60 ~ 130mm.
The method according to claim 6,
The method of manufacturing a thin non-oriented electrical steel sheet having excellent magnetic properties and shape of the entrance temperature during the rough rolling is 1000 ~ 1200 ℃.
The method according to claim 6,
The method of producing a non-oriented electrical steel sheet having excellent magnetic properties and shape that the exit temperature during the rough rolling is 900 ℃ or more.
The method according to claim 6,
The method of manufacturing the thin non-oriented electrical steel sheet having excellent magnetic properties and shape when the rough rolling speed is 20 ~ 50mpm.
The method according to claim 6,
The hot rolled steel sheet is a method of manufacturing a thin non-oriented electrical steel sheet excellent in magnetic properties and shape having a longitudinal thickness deviation of 30㎛ or less.
The method according to claim 6,
The hot rolled steel sheet is a manufacturing method of the thin non-oriented electrical steel sheet having excellent magnetic properties and shape of less than 2.3mm in thickness.
The method according to claim 6,
The hot rolled steel sheet is a method of manufacturing a thin non-oriented electrical steel sheet having excellent magnetic properties and shape that the area fraction of the recrystallized texture composed of {110} based on the thickness direction cross-section is 50% or more.

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