KR101296125B1 - Non-oriented electrical steel sheet with excellent magnetic property, and Method for manufacturing the same - Google Patents

Abstract

The present invention relates to a non-oriented electrical steel sheet, in weight% Al: 0.7-2.7%, Si: 0.2-1.0%, Mn: 0.2-1.7%, B: 0.001-0.004%, N: 0.001-0.004%, S : 0.0005 to 0.004%, remainder Fe and other unavoidably mixed impurities, Al, Mn, N, S, B is {[Al] + [Mn]} ≤ 2.0, 0.002 ≤ {[N] + [ S]} ≦ 0.006, 230 ≦ {([Al] + [Mn]) / ([N] + [S])} ≦ 1,000, 0.5 ≦ [B] / [N] ≦ 1.3 Provided is a non-oriented electrical steel sheet having excellent magnetic properties and a method of manufacturing the same. Accordingly, the additive density of Al, Si, Mn, N, S, and B is optimized to increase the distribution density of coarse inclusions, thereby improving grain growth and mobility of the magnetic walls, thereby improving magnetic properties, and having low hardness. Excellent high quality non-oriented electrical steel sheet can be produced.

Description

Non-oriented electrical steel sheet with excellent magnetic property, and Method for manufacturing the same

The present invention relates to the manufacture of non-oriented electrical steel sheet, by setting the additive components of the steel to the optimum setting to increase the distribution density of coarse inclusions in the steel, improve the growth of the grain and the mobility of the magnetic wall to improve the magnetism, ensuring low hardness The present invention relates to a high-quality non-oriented electrical steel sheet and a method of manufacturing the same that improves product productivity and punchability.

The present invention relates to the production of non-oriented electrical steel sheet used as the iron core material of the rotating machine, the non-oriented electrical steel sheet is an important component for converting electrical energy into mechanical energy, the magnetic properties are very important. Mainly mentioned as magnetic properties are iron loss and magnetic flux density. Iron loss is energy that disappears as heat during the energy conversion process, the lower the better, the higher the magnetic flux density is the power source of the rotor, the higher the better the energy efficiency.

In general, non-oriented electrical steel sheet adds Si as a main element to reduce iron loss. When the content of Si increases, the magnetic flux density decreases, and when the content of Si exceeds 3%, workability is lowered, which makes it difficult to cold roll. In addition, the die life is reduced when the customer punches. Therefore, attempts have been made to improve the magnetic and mechanical properties by reducing the content of Si and increasing the content of Al, but are not yet commercialized due to the difficulty of the high-quality non-oriented electrical steel sheet and the difficulty in mass production process. .

On the other hand, in order to obtain good magnetism in the non-oriented electrical steel sheet, it is necessary to control the impurities such as C, S, N, Ti, such as fine inclusions present in the steel to extremely low, thereby improving the growth of crystal grains. However, it is not easy to manage impurities very low in the manufacturing process of ordinary electrical steel sheet, and there is a disadvantage in that an increase in cost occurs in the steelmaking stage.

Impurities not removed in the steelmaking stage exist in the form of nitrides or sulfides in the slab during continuous casting, and inclusions such as nitrides or sulfides are redissolved as the slab is reheated to a temperature above 1,100 ° C for hot rolling. At the end of rolling, fine precipitates again.

The inclusions MnS and AlN, which are precipitated in general non-oriented electrical steel sheets, are observed to have a fine average size of about 50 nm, and the fine inclusions thus produced not only increase the hysteresis loss by inhibiting the growth of grains during annealing, but also magnetization. This reduces the permeability by preventing the city wall from moving.

Therefore, in the manufacturing process of the non-oriented electrical steel sheet, it is important to properly control the impurities from the steelmaking stage so that such fine inclusions do not exist, and to suppress the remaining inclusions to be re-used during hot rolling and to be deposited more finely.

The present invention was created to solve all the problems of the prior art as described above, by managing the component ratios of Al, Si, Mn, which are alloy elements of steel, and N and S, which are impurity elements, under optimum conditions. The purpose is to provide the highest quality non-oriented electrical steel sheet with high productivity and releasability due to its low hardness, which improves grain growth and mobility of magnetic walls by increasing the distribution density of the inclusions and reducing the incidence of fine inclusions. It is to be done.

The non-oriented electrical steel sheet of the present invention for solving the above problems by weight, Al: 0.7 ~ 2.7%, Si: 0.2 ~ 1.0%, Mn: 0.2 ~ 1.7%, B: 0.001 ~ 0.004%, N: 0.001 ~ 0.004%, S: 0.0005 to 0.004%, the balance Fe and other unavoidably mixed impurities, Al, Mn, N, S is contained so as to satisfy the composition formula of the following condition formulas 1 to 3, wherein B is 0.5 It is characterized in that it is contained so as to satisfy the condition of ≤ [B] / [N] ≤1.3.

{[Al] + [Mn]} ≤2.0 --------------------- Conditional Expression 1

0.002≤ {[N] + [S]} ≤0.006 --------------------- Conditional Expression 2

230≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,000 --------------------- Conditional Expression 3

[Al], [Mn], [N], [S], and [B] mean Al, Mn, N, S, and B contents (% by weight), respectively.

The non-oriented electrical steel sheet of the present invention is characterized in that the Al, Si, Mn is contained so as to satisfy the composition formula of the following conditional formulas 4 to 6.

1.0≤ {[Al] + [Si] + [Mn] / 2} ≤2.0 --------------------- Conditional Expression 4

0.7≤ [Al] / [Si] ≤14.0 --------------------- Conditional Expression 5

1≤ [Al] / [Mn] ≤8 --------------------- Conditional Expression 6

[Si] means the content (% by weight) of Si.

Non-oriented electrical steel sheet of the present invention is characterized in that the cross-sectional Vickers hardness (Hv1) of the final annealing plate is 140 or less.

The non-oriented electrical steel sheet of the present invention in weight percent, Al: 0.7-2.7%, Si: 0.2-1.0%, Mn: 0.2-1.7%, B: 0.001-0.004%, N: 0.001-0.004%, S: 0.0005 ~ 0.004%, remainder Fe and other inevitable incorporation of impurities, nitride and sulfide alone or inclusions are formed in the steel sheet, the distribution density of inclusions having an average size of 300nm or more is 0.02 / mm ² or more, B is contained so as to satisfy the condition of 0.5 ≦ [B] / [N] ≦ 1.3.

Method for producing a non-oriented electrical steel sheet of the present invention for solving the above problems by weight, Al: 0.7 ~ 2.7%, Si: 0.2 ~ 1.0%, Mn: 0.2 ~ 1.7%, B: 0.001 ~ 0.004%, N : 0.001% to 0.004%, S: 0.0005% to 0.004%, remainder Fe and other unavoidable impurities, wherein Al, Mn, N, S, and B are {[Al] + [Mn]} ≦ 2.0, 0.002 ≤ {[N] + [S]} ≤0.006, 230≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,000, 0.5≤ [B] / [N] ≤1.3 The slab contained to satisfy the composition formula of above is heated to 1,100 ℃ or more and then hot rolled, but hot finishing rolling is performed at 800 ℃ or more, and the hot rolled hot rolled sheet is annealed or hot rolled at a temperature range of 850 ~ 1,100 ℃. The plate annealing is omitted, pickled, cold rolled at a reduction ratio of 70 to 95%, and the cold rolled cold rolled sheet is finally annealed at a temperature range of 750 to 1,100 ° C.

In the method for producing a non-oriented electrical steel sheet of the present invention, Al, Si, Mn is 1.0≤ {[Al] + [Si] + [Mn] / 2} ≤2.0, 0.7≤ [Al] / [Si] ≤ 14.0, 1≤ [Al] / [Mn] ≤8, so as to satisfy the composition formula.

Method for producing a non-oriented electrical steel sheet of the present invention is characterized by controlling the distribution density of inclusions having an average size of 300nm or more to 0.02 pieces / mm ² or more.

According to the present invention, by appropriately managing the component ratios of the alloying elements of Al, Si, and Mn and the impurity elements of N and S to increase the distribution density of coarse inclusions, the growth of crystal grains and the mobility of the magnetic walls are improved, thereby providing excellent magnetic properties. High quality non-oriented electrical steel sheet having low hardness can be stably manufactured. In addition, the customer's processability and productivity is excellent, and the cost is reduced by lowering the production cost of the product.

1 is a view showing a composite inclusion in the non-oriented electrical steel sheet of the present invention.
FIG. 2 is divided based on whether [N] + [S] is the horizontal axis and [Al] + [Mn] is the vertical axis, and the distribution density of a large composite inclusion having an average size of 300 nm or more is 0.02 / mm ² or more. Graph shown by.

In order to solve the above technical problems, the present inventors have investigated the effects of alloying elements, impurity elements, and the relationship between the elements on the formation of inclusions, and the effects on magnetic properties and workability, respectively. In the alloying elements, Al, Si, Mn, and the impurity elements N and S content are properly adjusted, and Al / Si and Al / Mn, Al + Si + Mn / 2, Al + Mn, N + S, (Al + Mn By optimally managing the ratio of) / (N + S), it is possible to reduce the hardness of the steel sheet and to increase the distribution density of the large composite inclusions having an average size of 300 nm or more in the steel sheet, thereby greatly improving magnetic properties, The present invention has been completed by paying attention to the fact that punchability is improved.

In the present invention, by weight%, Al: 0.7-2.7%, Si: 0.2-1.0%, Mn: 0.2-1.7%, B: 0.001-0.004%, N: 0.001-0.004%, S: 0.0005-0.004%, remainder Fe and other inevitably incorporated impurities, wherein Al, Mn, N, and S are {[Al] + [Mn]} ≦ 2.0, 0.002 ≦ {[N] + [S]} ≦ 0.006, 230 ≦ { ([Al] + [Mn]) / ([N] + [S])} ≤1,000, 1.0≤ {[Al] + [Si] + [Mn] / 2} ≤2.0, 0.7≤ [Al] / [ The content of Si] ≤14.0 and 1≤ [Al] / [Mn] ≤8 is included so that the distribution density of nitrides and sulfides having an average size of 300 nm or more, or inclusions containing them, is 0.02 pieces / mm ² or more. It is characterized in that the high, thereby the best non-oriented electrical steel sheet having excellent magnetic properties and excellent workability due to the low hardness of Vickers hardness (Hv1) 140 or less.

In the present invention, 0.3 to 0.5% of Al is first added in the steelmaking step to perform deoxidation, and then the remaining alloying elements are added, and after the addition of the remaining alloying elements, the temperature of the molten steel is maintained at 1,500 to 1,600 ° C. A slab having a composition was prepared, and the slab was heated to a temperature of 1,100 to 1,250 ° C. and then hot rolled, but hot finishing rolling was performed at 800 ° C. or higher, and the hot rolled hot rolled sheet was annealed at a temperature range of 850 to 1,100 ° C. After pickling or omitting, pickling, cold rolling at a reduction ratio of 70 to 95%, and finally annealing the cold rolled cold rolled plate at a temperature range of 750 to 1,100 ° C. to produce non-oriented electrical steel having excellent magnetic properties and workability. It is characterized by.

In the case of Al, Si, and Mn, which are alloying elements of steel, the alloying elements are added to lower iron loss of the steel sheet, but as the added content thereof increases, the magnetic flux density decreases and the workability of the material is deteriorated. In addition, these alloying components should be set properly to improve magnetic flux density as well as iron loss and maintain hardness at an appropriate level.

In addition, Al and Mn combine with N and S which are impurity elements to form inclusions such as nitride and sulfide. Since such inclusions have a great influence on the magnetism, there is a need to increase the frequency of formation of the inclusions so as to minimize deterioration of the magnetic properties.

The present inventors first discovered that when Al, Mn, Si, N, and S were contained so as to satisfy specific conditions, a huge complex inclusion composed of nitrides or sulfides was formed, and the workability was adjusted by adjusting the distribution density of such composite inclusions. The present invention has been proposed in view of the fact that the magnetism is greatly improved despite having a minimum amount of deteriorating alloying elements.

First, the reason for limiting the content ratio between the range and the component elements constituting the present invention will be described.

[Al: 0.7-2.7 wt%]

Al is added because it increases the specific resistance of the material, lowers iron loss and forms nitride, and is added at 0.7-2.7% to form coarse nitride. If the Al content is less than 0.7%, the inclusions cannot be sufficiently grown. If the Al content is more than 2.7%, the workability is deteriorated and problems occur in all processes such as steelmaking and continuous casting, so that it cannot be produced by the normal process.

[Si: 0.2-1.0 wt%]

Si serves to lower the iron loss by increasing the specific resistance of the material, it is difficult to expect the effect of reducing iron loss when contained less than 0.2%, productivity and punchability is inferior due to the increase in hardness of the material when contained above 1.0%.

[Mn: 0.2-1.7 wt%]

Mn improves iron resistivity and forms sulfides by increasing the specific resistance of the material, and the inclusion coarsening effect is exerted when the content is 0.2% or more. When Mn is contained in excess of 1.7%, the content of Mn is preferably limited to 0.2 to 1.7% because it promotes the formation of [111] aggregates, which is disadvantageous to magnetism.

[B: 0.0010-0.0040 weight%]

B, in combination with N, plays an important role in coarse inclusions at the beginning of steelmaking and contributes to the improvement of productivity during steelmaking. If the amount of B added is less than 0.0010%, it is not preferable because it is not effective for shortening the initial steelmaking time, and if it exceeds 0.0040%, the magnetic inferiority.

The amount of B added is preferably controlled in consideration of the amount of N as an impurity. In other words, the ratio of [B] / [N] is preferably controlled to 0.5 to 1.3 because, when [B] / [N] is less than 0.5, it is not helpful for formation of coarse inclusions. This is because steel production is inferior because Al has to be added separately, and when [B] / [N] exceeds 1.3, excessively added B infers magnetic.

[N: 0.001-0.004 wt%]

N is an impurity element, in which fine nitride is formed during the manufacturing process to suppress grain growth and inferior iron loss. Therefore, it is necessary to suppress the formation of nitride, but this requires additional cost and processing time, so it is not economical. It is more desirable to reduce the impact. In order to grow the inclusions in this manner, it is essential to control the N to 0.001% to 0.004%. When N exceeds 0.004%, coarsening of inclusions is not achieved and iron loss is increased, and more preferably, N is contained in 0.003% or less.

[S: 0.0005-0.004 wt%]

S is an impurity element, which forms fine sulfides during the manufacturing process, inhibits grain growth, and infers iron loss. Therefore, the formation of sulfides should be suppressed, but this requires additional cost and processing time, and thus it is not economical. Therefore, as described below, the inclusions are coarsely grown by using an element having a high affinity for S as an impurity element to crystal grain growth. It is more desirable to reduce the impact. In order to grow the inclusions in this way, it is essential to control the S in the range 0.0005 to 0.004%. If S exceeds 0.004%, coarsening of inclusions is not achieved, and iron loss is increased. More preferably, S is contained at 0.003% or less.

In addition to the impurity elements described above, impurities that are inevitably mixed such as C and Ti may be included. Since C causes self aging, the C content should be limited to 0.004% or less, preferably 0.003% or less. Ti promotes the growth of the [111] aggregate structure, which is an undesirable crystal orientation in the non-oriented electrical steel sheet, so it is preferable to limit it to 0.004% or less, more preferably 0.002% or less.

In the present invention, the total amount of Al and Mn [Al] + [Mn] is limited to 2.0% or less, which means that when the total amount of Al and Mn exceeds 2.0%, the fraction of the [111] aggregate tissue, which is disadvantageous to magnetism, increases and the magnetic properties are increased. Because it gets feverish. When the total amount of Al and Mn is less than 0.9%, nitrides, sulfides, or two complex inclusions are not coarse to form magnetic heat. However, in the present invention, Al is contained in an amount of 0.7% or more and Mn is 0.2% or more. Since the total amount of Al and Mn is 0.9% or more, magnetic deterioration is prevented.

In the present invention, the total amount of N and S [N] + [S] is limited to 0.002% to 0.006%, because inclusions grow coarsely in this range. When the total amount of N and S exceeds 0.006%, the fraction of fine inclusions increases and the magnetism deteriorates.

In the present invention, Al, Mn, N, and S are contained so as to satisfy the composition formula of 230≤ ([Al] + [Mn]) / ([N] + [S]) ≤1,000. Here, [Al], [Mn], [N], and [S] mean content (wt%) of Al, Mn, N, and S, respectively. Within this range, iron loss is improved by increasing coarse inclusions and increasing the density of distribution of large composite inclusions. Outside this range, coarsening of inclusions is not coarse, formation frequency of huge composite inclusions is low, and it is disadvantageous to magnetism. Is formed.

1 is a view showing a composite inclusion in the non-oriented electrical steel sheet of the present invention.

Within the range in which the Al, Mn, N, and S contents are optimally managed, inclusions grow more than several times as compared to conventional materials, increasing the frequency of formation of coarse composite inclusions having an average size of 300 nm or more. The fine inclusions having an average size is reduced to improve the magnetism, and when the distribution density of the giant composite inclusion is 0.02 pieces / mm ² or more, the magnetism is greatly improved.

The formation of such coarse composite inclusions is assumed to occur in the steelmaking stage, and the exact mechanism of formation thereof is not clear yet, but Al-based oxides and nitrides are formed by deoxidation during initial Al injection in the steelmaking stage. When adding alloying elements such as Al and Mn and bubbling, the Al-based oxide / nitride is grown in the component system satisfying the component ratios of Al, Mn, Si, N, and S as defined in the present invention, and at the same time, the Mn-based sulfide Presumably due to precipitation in the stomach.

FIG. 2 is divided based on whether [N] + [S] is the horizontal axis and [Al] + [Mn] is the vertical axis, and the distribution density of a large composite inclusion having an average size of 300 nm or more is 0.02 / mm ² or more. It is a graph shown.

Referring to the illustration of Fig. 2, the total amount of Al and Mn [Al] + [Mn] is 2.0% or less, and the total amount of N and S [N] + [S] is 0.002 to 0.006 and Al and In the scope of the present invention (inside the thick line) where ([Al] + [Mn]) / ([N] + [S]), which is the ratio of the total amount of Mn to the total amount of N and S, is 230 to 1,000, While the distribution density of the large composite inclusions having an average size of 300 nm or more is greater than 0.02 / mm ² , the magnetic properties are excellent, while the coarse inclusions do not form within the range outside the present invention, and the distribution density of large composite inclusions having an average size of 300 nm or more is exceeded. Is lower than 0.02 pieces / mm ² and the magnetism is degraded due to inferior texture.

Coarse inclusions have been observed to have an average size of 300 nm or more mainly due to the compounding of nitrides and sulfides, but also includes several nitrides or several sulfides having an average size of 300 nm or more, and nitrides or sulfides alone It can be included also grown to 300nm or more. Here, the average size of the inclusions was taken as the value obtained by measuring the longest length and the shortest length of the inclusions in the cross section of the steel sheet and averaging them.

[Al] / [Si] which is a ratio of Al to Si in the present invention is preferably limited to 0.7 to 14.0. This is because when the ratio of Al to Si is 0.7 to 14.0, the grain growth is excellent and the hardness of the material is lowered, thereby improving productivity and punchability. If [Al] / [Si] is less than 0.7, the inclusions do not grow significantly, and the grain growth is deteriorated and the magnetism is deteriorated. If [Al] / [Si] exceeds 14.0, the texture of the material deteriorates and the magnetic flux density becomes heat. To be harmed.

[Al] / [Mn], which is a ratio of Al to Mn in the present invention, is preferably limited to 1-8. This is because when the ratio of Al to Mn is 1 to 8, the inclusion loss is excellent and the iron loss characteristics are excellent. On the contrary, when the Al ratio is out of this range, the growth rate of the inclusion is lowered and the fraction of the texture that is favorable for magnetism is reduced.

Next, the ratio limitation of the alloy component related to a specific resistance is demonstrated. Recently, the demand for high magnetic flux density products to achieve high efficiency in the motor is rapidly increasing, and accordingly, the demand for non-oriented electrical steel sheet to improve the magnetic flux density by lowering the specific resistance is increasing. Therefore, it is appropriate to control the specific resistance to 25 or more in order to lower the specific resistance to 36 or less to increase the magnetic flux density and to cope with high-speed rotation.

The relationship between the component system and the resistivity was calculated using the following empirical formula.

ρ = 13.25 + 11.3 ([Al] + [Si] + [Mn] / 2) (ρ: resistivity)

According to this empirical formula, [Al] + [Si] + [Mn] / 2 should be managed at 1.0 ~ 2.0% to satisfy specific resistivity 25 ~ 36.

Hereinafter, a method of manufacturing a non-oriented electrical steel sheet according to the present invention. In the manufacturing method of the non-oriented electrical steel sheet according to the present invention, in the steelmaking step, first, 0.3 to 0.5% of the total amount of Al is first added, and after the deoxidation in the steel is sufficiently generated, the remaining alloy elements may be added to produce molten steel. However, since the B added in an appropriate content can form coarse composite inclusions in combination with N at the beginning of steelmaking, molten steel is preferably prepared by bubbling the alloying elements of the steel at the same time in terms of improving productivity of steelmaking.

In addition, when B is added to satisfy the condition of 0.5≤ [B] / [N] ≤1.3, the inclusions are sufficiently grown even if the initial Al injection method in which some Al is separately added in the initial steelmaking stage is sufficient, so that the manufacturing process may be performed. Can be simplified.

After the alloying element is added to maintain the temperature of the molten steel to 1,500 ~ 1,600 ℃ to produce enough inclusions in the steel can be produced by solidification in the continuous casting process can be produced slab.

Subsequently, the slab is charged to a heating furnace and reheated to a temperature of 1,100 ° C or more and 1,250 ° C or less. When the slab is heated to a temperature exceeding 1,250 ℃, the precipitate that harms the magnetic can be re-dissolved and finely precipitated after hot rolling, so the slab is heated at a temperature below 1,250 ℃.

Once the slab is reheated, it is then hot rolled. It is preferable to perform hot finishing rolling at the time of hot rolling at the temperature of 800 degreeC or more.

Hot rolled hot rolled sheet is annealed at a temperature of 850 ~ 1,100 ℃. If the hot-rolled sheet annealing temperature is less than 850 ℃, the structure does not grow or grow fine, the magnetic flux density is less synergistic effect, if the annealing temperature exceeds 1,100 ℃ magnetic properties are rather deteriorated, rolling workability due to the deformation of the plate shape This can be worse, the temperature range is limited to 850 ~ 1,100 ℃. The more preferable annealing temperature of a hot rolled sheet is 950-1,100 degreeC. Hot-rolled sheet annealing is performed in order to increase the crystal orientation favorable to magnetic as needed, but it is also possible to omit hot-rolled sheet annealing.

After the hot rolled sheet is annealed or omitted, the hot rolled sheet is pickled, and then cold rolled at a reduction ratio of 70 to 95% to form a predetermined sheet thickness. In the present invention, the addition amount of Si, Mn, Al alloy elements affecting the cold rolling is appropriately adjusted, and thus the cold rolling is excellent. Therefore, high rolling reduction can be applied. Thus, only one cold rolling can be used as a thin plate having a thickness of about 0.15 mm. Manufacturing is possible. When cold rolling is required, two cold rolling including intermediate annealing may be performed, or two annealing may be applied.

The cold-rolled cold-rolled sheet is subjected to final annealing. If the final annealing temperature is less than 750 ℃ recrystallization does not occur sufficiently, if the final annealing temperature exceeds 1,100 ℃ because the surface layer of the oxide layer is deeply formed and the magnetic is lowered, the final annealing is preferably carried out at 750 ~ 1,100 ℃ temperature.

The final annealed steel sheet is shipped to the customer after insulation coating treatment in the usual way. When the insulation coating is applied, it is possible to apply a conventional coating material, and any of chromium-based (Cr-type) or chromium-free (Cr-free type) can be used without limitation.

Hereinafter, the present invention will be described in detail with reference to Examples. Unless stated otherwise in the examples below, the ingredient content is expressed in weight percent.

Were vacuum-melted in a laboratory to produce ingots having the compositions shown in Table 1 below. After adding 0.3 to 0.5% of Al to the molten steel to promote the formation of inclusions, the remaining Al, Si, and Mn were added to prepare a steel ingot. Impurities C, S, N, and Ti of the material were all controlled to 0.002%. Each material was heated to 1,150 ° C. and hot-rolled at 850 ° C. to produce a hot rolled sheet having a plate thickness of 2.3 mm. The hot rolled hot rolled sheet was annealed at 1,050 ° C. for 4 minutes and then pickled. After cold rolling, the sheet thickness was 0.50 mm and final annealing was performed at 900 ° C. for 30 seconds.

Inclusion size and inclusion distribution density, iron loss, magnetic flux density and hardness for each are shown in Table 2 below. Sample preparation for observation of inclusions was performed using a replica method, which is a common method for steel materials, and a transmission electron microscope was used as a device. At this time, the acceleration voltage was applied to 200kV.

Steel grade Al Si Mn C S N Ti A1 1.5 0.2 0.2 0.002 0.002 0.002 0.002 A2 1.5 0.2 0.5 0.002 0.002 0.002 0.002 A3 0.7 0.2 0.5 0.002 0.002 0.002 0.002 A4 2.7 0.5 0.3 0.002 0.002 0.002 0.002 A5 1.7 0.5 0.3 0.002 0.002 0.002 0.002 A6 0.7 0.5 0.3 0.002 0.002 0.002 0.002 A7 0.5 0.5 0.5 0.002 0.002 0.002 0.002 A8 0.5 0.5 0.5 0.002 0.002 0.002 0.002 A9 2.2 0.5 0.2 0.002 0.002 0.002 0.002 A10 1.2 0.5 0.2 0.002 0.002 0.002 0.002 A11 1.0 0.1 0.2 0.002 0.002 0.002 0.002 A12 1.2 0.2 0.2 0.002 0.002 0.002 0.002 A13 1.0 0.2 0.2 0.002 0.002 0.002 0.002 A14 2.2 0.7 0.2 0.002 0.002 0.002 0.002 A15 0.7 0.7 0.2 0.002 0.002 0.002 0.002 A16 1.3 0.2 0.7 0.002 0.002 0.002 0.002 A17 1.5 0.2 1.0 0.002 0.002 0.002 0.002 A18 1.2 0.2 1.0 0.002 0.002 0.002 0.002 A19 0.9 0.5 1.0 0.002 0.002 0.002 0.002 A20 0.9 0.7 0.8 0.002 0.002 0.002 0.002 A21 1.0 0.5 0.8 0.002 0.002 0.002 0.002

Steel grade Al /
Si Al /
Mn Al +
Mn N + S (Al + Mn)
/ (N + S) Al + Si
+ Mn / 2 Inclusion
size
(Nm) Inclusion
Distribution density
(1 / mm ² ) Iron loss
(W15
/ 50) Magnetic flux
density
(B50) Hardness Remarks A1 7.5 7.5 1.7 0.0040 425 1.8 450 0.40 3.2 1.73 140 Honor A2 7.5 3.0 2.0 0.0040 500 2.0 500 0.35 3.0 1.73 140 Honor A3 3.5 1.4 1.2 0.0040 300 1.2 300 0.30 4.0 1.74 110 Honor A4 5.4 9.0 3.0 0.0040 750 3.4 250 0.01 3.0 1.68 157 Comparative example A5 3.4 5.7 2.0 0.0040 500 2.4 250 0.01 2.9 1.69 145 Comparative example A6 1.4 2.3 1.0 0.0040 250 1.4 450 0.05 3.5 1.74 115 Honor A7 1.0 1.0 1.0 0.0040 250 1.3 50 0.01 4.5 1.74 110 Comparative example A8 1.0 1.0 1.0 0.0040 250 1.3 75 0.01 4.5 1.74 110 Comparative example A9 4.4 11.0 2.4 0.0040 600 2.8 400 0.01 2.8 1.68 150 Comparative example A10 2.4 6.0 1.4 0.0040 350 1.8 600 0.15 3.2 1.73 130 Honor A11 10 5.0 1.2 0.0040 300 1.2 250 0.01 4.5 1.74 105 Comparative example A12 6.0 6.0 1.4 0.0040 350 1.5 400 0.20 3.5 1.74 105 Honor A13 5.0 5.0 1.2 0.0040 300 1.3 300 0.18 3.6 1.74 110 Honor A14 3.1 11.0 2.4 0.0040 600 3.0 400 0.01 2.8 1.69 160 Comparative example A15 1.0 3.5 0.9 0.0040 225 1.5 150 0.01 3.9 1.74 130 Comparative example A16 6.5 1.9 2.0 0.0040 500 1.9 350 0.25 2.9 1.72 130 Honor A17 7.5 1.5 2.5 0.0040 625 2.2 250 0.01 2.8 1.69 140 Comparative example A18 6.0 1.2 2.2 0.0040 550 1.9 250 0.01 2.9 1.70 130 Comparative example A19 1.8 0.9 1.9 0.0040 475 1.9 200 0.01 3.2 1.70 135 Comparative example A20 1.3 1.1 1.7 0.0040 425 2.0 350 0.05 3.5 1.73 140 Honor A21 2.0 1.3 1.8 0.0040 450 1.9 400 0.05 3.3 1.73 140 Honor

In the case of steel grades A1 to A3, A6, A10, A12, A13, A16, A20, and A21 belonging to the scope of the present invention, the hardness is low, so that the productivity and customer punchability are excellent, and coarse inclusions of 300 nm or more in size are observed and the distribution thereof. Its density is higher than 0.02 (1 / mm ² ) and it is excellent in magnetism.

On the other hand, steel grades A4, A9, and A14 contained Al / Mn ratios and Al + Mn contents outside the scope of the present invention, and no inclusions having a size of more than 300 nm were observed, and iron loss and magnetic flux density were inferior. In steel A19, inclusions having a size of 300 nm or more out of the range of Al / Mn were not observed, and iron loss and magnetic flux density were inferior. In steel grades A17 and A18, inclusions having Al + Mn outside the scope of the present invention having a size of 300 nm or more were not observed, and iron loss and magnetic flux density were inferior. Steel grades A4, A5, A9 and A14 were inferior in productivity and punchability because Al + Si + Mn / 2 had high hardness outside the scope of the present invention.

Vacuum dissolution in the lab produced a steel ingot as shown in Table 3 below. After adding 0.3 to 0.5% of Al to the molten steel to promote the formation of inclusions, the remaining Al, Si, and Mn were added to prepare a steel ingot. At this time, the ingredients were adjusted by varying the content of impurities N and S of the material. Each material was heated to 1,150 ° C. and hot-rolled at 850 ° C. to produce a hot rolled sheet having a plate thickness of 2.3 mm. The hot rolled hot rolled sheet was annealed at 1,050 ° C. for 4 minutes and then pickled. After cold rolling, the sheet thickness was 0.50 mm and final annealing was performed at 900 ° C. for 30 seconds.

Inclusion size and inclusion distribution density, iron loss, magnetic flux density, and hardness for each are shown in Table 4 below. Sample preparation for observation of inclusions was performed using a replica method, which is a common method for steel materials, and a transmission electron microscope was used as a device. At this time, the acceleration voltage was applied to 200kV.

Steel grade Al Si Mn C S N Ti B1 1.0 0.5 0.3 0.0030 0.0010 0.0010 0.0020 B2 0.7 0.3 0.2 0.0030 0.0030 0.0030 0.0020 B3 0.7 0.3 0.5 0.0030 0.0020 0.0030 0.0020 B4 0.7 0.5 0.3 0.0030 0.0010 0.0025 0.0020 B5 1.0 0.3 0.7 0.0030 0.0005 0.0005 0.0020 B6 1.0 0.3 0.7 0.0030 0.0040 0.0020 0.0020 B7 1.2 0.5 1.0 0.0030 0.0020 0.0020 0.0020 B8 1.2 0.2 0.3 0.0030 0.0015 0.0010 0.0020 B9 0.9 0.5 0.8 0.0030 0.0020 0.0020 0.0020 B10 0.9 0.5 0.8 0.0030 0.0040 0.0030 0.0020 B11 0.9 0.5 0.5 0.0030 0.0030 0.0030 0.0020 B12 0.9 0.5 0.5 0.0030 0.0020 0.0025 0.0020 B13 0.9 0.5 0.5 0.0030 0.0005 0.0005 0.0020

Steel grade Al /
Si Al /
Mn Al +
Mn N + S (Al + Mn)
/ (N + S) Al + Si
+ Mn / 2 Inclusion
size
(Nm) Inclusion
Distribution density
(1 / mm ² ) Iron loss
(W15
/ 50) Magnetic flux
density
(B50) Hardness Remarks B1 2.0 3.3 1.3 0.0020 650 1.7 350 0.150 3.2 1.73 135 Honor B2 2.3 3.5 0.9 0.0060 150 1.1 200 0.010 4.2 1.71 130 Comparative example B3 2.3 1.4 1.2 0.0050 240 1.3 300 0.200 3.5 1.74 130 Honor B4 1.4 2.3 1.0 0.0035 286 1.4 450 0.050 3.4 1.73 130 Honor B5 3.3 1.4 1.7 0.0010 1700 1.7 50 0.010 3.5 1.69 140 Comparative example B6 3.3 1.4 1.7 0.0060 283 1.7 350 0.200 3.2 1.74 140 Honor B7 2.4 1.2 2.2 0.0040 550 2.2 250 0.010 2.9 1.68 140 Comparative example B8 6.0 4.0 1.5 0.0025 600 1.6 450 0.070 3.3 1.74 140 Honor B9 1.8 1.1 1.7 0.0040 425 1.8 550 0.080 3.1 1.73 135 Honor B10 1.8 1.1 1.7 0.0070 243 1.8 250 0.010 3.5 1.69 135 Comparative example B11 1.8 1.8 1.4 0.0060 233 1.7 500 0.150 3.2 1.73 135 Honor B12 1.8 1.8 1.4 0.0045 311 1.7 600 0.180 3.2 1.74 135 Honor B13 1.8 1.8 1.4 0.0010 1400 1.7 50 0.018 3.7 1.72 135 Comparative example

Steel grades B1, B3, B4, B6, B8, B9, B11, and B12, which satisfy the conditions of Al / Si, Al / Mn, and Al + Mn, which are within the scope of the present invention, and whose total amount of N and S is controlled from 0.0020 to 0.0060. In this case, the hardness is low, the productivity and customer punchability is excellent, coarse inclusions of 300 nm or more in size are observed, and the distribution density is higher than 0.02 (1 / mm ² ), which is excellent in magnetic properties.

On the other hand, in the case of steel grades B5, B10, and B13, inclusions having a size of 300 nm or more beyond the scope of the present invention were not observed, and iron loss and magnetic flux density were inferior. In steel B7, inclusions having Al + Mn in the range of 300 nm or more out of the scope of the present invention were not observed, and iron loss and magnetic flux density were inferior.

Vacuum dissolution in the lab produced a steel ingot as shown in Table 5 below. At this time, some of the Al was added to the molten steel by 0.3-0.5% to promote inclusion formation, and then the initial Al addition method was used to inject the remaining Al, Si, and Mn. Ingot was prepared by simultaneously adding Al, Si, Mn, and B. Each material was heated to 1,150 ° C. and hot-rolled at 850 ° C. to produce a hot rolled sheet having a plate thickness of 2.3 mm. The hot rolled hot rolled sheet was annealed at 1,050 ° C. for 4 minutes and then pickled. After cold rolling, the sheet thickness was 0.50 mm and final annealing was performed at 900 ° C. for 30 seconds.

Inclusion size and inclusion distribution density, iron loss, and magnetic flux density for each are shown in Table 6 below. Sample preparation for observation of inclusions was performed using a replica method, which is a common method for steel materials, and a transmission electron microscope was used as a device. At this time, the acceleration voltage was applied to 200kV. In addition, the initial Al addition method is indicated by ○ for the initial deoxidation presence, and the initial Al addition method is indicated by × for the initial deoxidation presence and shown together in Table 3-2.

Steel grade Al Si Mn B C S N Ti C1 1.5 0.2 0.5 0 0.0030 0.0030 0.0020 0.0025 C2 1.5 0.2 0.5 0.001 0.0030 0.0030 0.0020 0.0025 C3 1.5 0.2 0.5 0.002 0.0030 0.0030 0.0020 0.0025 C4 1.5 0.2 0.5 0.003 0.0030 0.0030 0.0020 0.0025 C5 1.5 0.2 0.5 0.004 0.0030 0.0030 0.0020 0.0025 C6 1.5 0.2 0.5 0.004 0.0030 0.0030 0.0020 0.0025 C7 0.9 0.7 0.8 0 0.0030 0.0030 0.0020 0.0025 C8 0.9 0.7 0.8 0.001 0.0030 0.0030 0.0020 0.0025 C9 0.9 0.7 0.8 0.001 0.0030 0.0030 0.0020 0.0025 C10 0.9 0.7 0.8 0.002 0.0030 0.0030 0.0020 0.0025 C11 0.9 0.7 0.8 0.003 0.0030 0.0030 0.0020 0.0025 C12 0.9 0.7 0.8 0.004 0.0030 0.0030 0.0020 0.0025

Steel grade Al / Si Al / Mn Al + Mn N + S (Al + Mn)
/ (N + S) B / N Inclusion
size
(Nm) Inclusion
Distribution density
(1 / mm ² ) Iron loss
(W15 /
50) Magnetic flux
density
(B50) Early
Deoxidation Remarks C1 7.5 3.0 2.0 0.0050 400 0.0 300 0.03 3.0 1.73 O Comparative example C2 7.5 3.0 2.0 0.0050 400 0.5 400 0.03 2.8 1.74 X Honor C3 7.5 3.0 2.0 0.0050 400 1.0 380 0.05 2.8 1.75 X Honor C4 7.5 3.0 2.0 0.0050 400 1.5 100 0.01 3.3 1.72 O Comparative example C5 7.5 3.0 2.0 0.0050 400 1.3 350 0.03 2.9 1.74 X Honor C6 7.5 3.0 2.0 0.0050 400 1.0 350 0.04 3.0 1.74 X Honor C7 1.3 1.1 1.7 0.0050 340 0.0 350 0.03 3.7 1.72 O Comparative example C8 1.3 1.1 1.7 0.0050 340 0.3 400 0.03 3.5 1.73 O Comparative example C9 1.3 1.1 1.7 0.0050 340 0.5 350 0.03 3.2 1.74 X Honor C10 1.3 1.1 1.7 0.0050 340 1.0 380 0.05 3.1 1.75 X Honor C11 1.3 1.1 1.7 0.0050 340 1.5 180 0.01 3.7 1.72 O Comparative example C12 1.3 1.1 1.7 0.0050 340 1.3 350 0.05 3.0 1.74 X Honor

From the results in Table 6, steel grades C2, C3, C5, C6, C9, C10, and C12 contained 0.001 to 0.004% of B and [B] / [N] in the range of 0.5 to 1.3, so that Although it does not depend on the method of pre-injecting a part of Al and the remaining Al and alloying elements, the magnetic properties are excellent, and the steelmaking time is shortened, and thus the steelmaking productivity is good.

Since steel grades C1, C7 and C8 had less than 0.5 [B] / [N], deoxidation had to be carried out by the initial Al injection method in the steelmaking stage, and the steelmaking productivity was low due to the time required for steelmaking. Steel grades C4 and C11 were inferior in magnetism with [B] / [N] exceeding 1.3.

Claims (13)

By weight, Al: 0.7-2.7%, Si: 0.2-1.0%, Mn: 0.2-1.7%, B: 0.001-0.004%, N: 0.001-0.004%, S: 0.0005-0.004%, C: 0.004% Ti: 0.004% or less, balance Fe and other inevitably mixed impurities, Al, Mn, N, S, Si is contained to satisfy the compositional formulas of the following conditional formulas 1 to 6, wherein B is 0.5 Non-oriented electrical steel sheet having excellent magnetic properties so as to satisfy the condition of ≤ [B] / [N] ≤1.3.
{[Al] + [Mn]} ≤2.0 --------------------- Conditional Expression 1
0.002≤ {[N] + [S]} ≤0.006 --------------------- Conditional Expression 2
230≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,000 --------------------- Conditional Expression 3
1.0≤ {[Al] + [Si] + [Mn] / 2} ≤2.0 --------------------- Conditional Expression 4
1≤ [Al] / [Mn] ≤8 --------------------- Conditional Expression 5
0.7≤ [Al] / [Si] ≤14.0 --------------------- Conditional Expression 6
[Al], [Mn], [N], [S], [B], and [Si] mean content (wt%) of Al, Mn, N, S, B, and Si, respectively. delete delete The method according to claim 1,
Non-oriented electrical steel sheet having excellent magnetic properties in which the inclusions of nitride and sulfide alone or in combination thereof are formed in the steel sheet, and the distribution density of inclusions having an average size of 300 nm or more is 0.02 pieces / mm ² or more. The method according to claim 1,
Non-oriented electrical steel sheet having excellent magnetic properties with a Vickers hardness (Hv1) of 140 or less in the final annealing plate. delete By weight, Al: 0.7-2.7%, Si: 0.2-1.0%, Mn: 0.2-1.7%, B: 0.001-0.004%, N: 0.001-0.004%, S: 0.0005-0.004%, C: 0.004% Ti: 0.004% or less, balance Fe and other inevitably mixed impurities, wherein Al, Mn, N, S, B, and Si are {[Al] + [Mn]} ≤2.0, 0.002≤ {[ N] + [S]} ≤0.006, 230≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,000, 0.5≤ [B] / [N] ≤1.3, 1.0≤ The slab contained so as to satisfy the compositional formula of {[Al] + [Si] + [Mn] / 2} ≤2.0, 1≤ [Al] / [Mn] ≤8, 0.7≤ [Al] / [Si] ≤14.0 After heating to a temperature of 1,100 ~ 1,250 ℃ and hot rolling, hot finish rolling is carried out at 800 ℃ or more, the hot rolled hot rolled sheet in the temperature range of 850 ~ 1,100 ℃ or the hot rolled sheet annealing is omitted, After pickling, cold rolling is carried out at a reduction ratio of 70 to 95%, and a method for producing non-oriented electrical steel sheet having excellent magnetic properties in which the cold rolled cold rolled sheet is finally annealed at a temperature range of 750 to 1,100 ° C.
[Al], [Mn], [N], [S], [B], and [Si] mean content (wt%) of Al, Mn, N, S, B, and Si, respectively. delete delete The method of claim 7,
In the final annealed steel sheet, the inclusions of nitrides and sulfides alone or in combination thereof are formed, and the manufacturing method of the non-oriented electrical steel sheet having excellent magnetic properties controlling the distribution density of inclusions having an average size of 300 nm or more to 0.02 pieces / mm ² or more. By weight, Al: 0.7-2.7%, Si: 0.2-1.0%, Mn: 0.2-1.7%, B: 0.001-0.004%, N: 0.001-0.004%, S: 0.0005-0.004%, C: 0.004% Ti: 0.004% or less, balance Fe and other inevitably mixed impurities, Al, Mn, N, S, Si is contained to satisfy the compositional formulas of the following conditional formulas 1 to 6, wherein B is 0.5 Non-oriented electrical steel slab contained so as to satisfy the condition of ≤ [B] / [N] ≤1.3.
{[Al] + [Mn]} ≤2.0 --------------------- Conditional Expression 1
0.002≤ {[N] + [S]} ≤0.006 --------------------- Conditional Expression 2
230≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,000 --------------------- Conditional Expression 3
1.0≤ {[Al] + [Si] + [Mn] / 2} ≤2.0 --------------------- Conditional Expression 4
1≤ [Al] / [Mn] ≤8 --------------------- Conditional Expression 5
0.7≤ [Al] / [Si] ≤14.0 --------------------- Conditional Expression 6
[Al], [Mn], [N], [S], [B], and [Si] mean content (wt%) of Al, Mn, N, S, B, and Si, respectively. delete delete

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