KR101296127B1 - 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, Al: 1.0 to 3.0% by weight, Si: 0.5 to 2.5%, Mn: 0.5 to 2.0%, N: 0.001 to 0.004%, S: 0.0005 to 0.004%, balance Fe and other inevitably incorporated impurities, wherein Al, Mn, N, and S are {[Al] + [Mn]} ≦ 3.5, 0.002 ≦ {[N] + [S]} ≦ 0.006, 300 ≦ { ([Al] + [Mn]) / ([N] + [S])} ≤ 1,400, a non-oriented electrical steel sheet containing excellent magnetic properties and having a fraction of 3% or more of the cube texture of the cross section It provides a manufacturing method. Accordingly, by optimizing the additive ingredients of Al, Si, Mn, N, and S, the coarse inclusions increase the distribution density, thereby improving grain growth and mobility of the magnetic walls, and excellent magnetic properties and low hardness. 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.

In terms of the aggregate structure, the non-oriented electrical steel sheet is most ideally located in the direction (ND) perpendicular to the surface of the steel sheet is easy to magnetize <100>, in particular, as shown in Figure 3 (a) The higher the degree of integration of the cube assembly ({001} <100>), the better the magnetic properties. On the other hand, as shown in FIG. 3 (b), the α-fiber is arranged in the rolling direction in which <110> is less easily magnetized than <100>, and <111> is less easily magnetized than <100>. It is preferable that the degree of integration of the? -Fiber in which the orientation is arranged in the rolling vertical direction is low.

The formation of these textures is closely related to alloying system, recrystallization temperature condition, grain size and growth. In general, non-oriented electrical steel sheet, such as cube texture ({001} <100>) during cold rolling and grain growth, The fraction of favorable orientations is reduced so that the value is reduced to less than 3%. Therefore, in order to manufacture non-oriented electrical steel sheet having excellent magnetic properties, it is very important to develop a component system and to set recrystallization annealing conditions to increase the density of cube texture.

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.

Non-oriented electrical steel sheet of the present invention for solving the above problems by weight, Al: 1.0 ~ 3.0%, Si: 0.5 ~ 2.5%, Mn: 0.5 ~ 2.0%, N: 0.001 ~ 0.004%, S: 0.0005 ~ 0.004%, balance Fe and other inevitable impurities, Al, Mn, N, S is contained to satisfy the compositional formula of the following conditional formulas 1 to 3, the fraction of the cube texture of the cross-section is 3% or more It is characterized by.

{[Al] + [Mn]} ≤3.5 --------------------- Conditional Expression 1

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

300≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,400 --------------------- Conditional Expression 3

[Al], [Mn], [N], and [S] mean Al, Mn, N, and S 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.

1.7≤ {[Al] + [Si] + [Mn] / 2} ≤5.5 --------------------- Conditional Expression 4

0.6≤ [Al] / [Si] ≤4.0 --------------------- 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 by weight, Al: 1.0 ~ 3.0%, Si: 0.5 ~ 2.5%, Mn: 0.5 ~ 2.0%, N: 0.001 ~ 0.004%, S: 0.0005 ~ 0.004%, balance Fe and It is composed of other inevitable incorporation of impurities, nitride and sulfide alone or inclusions are formed in the steel sheet, the distribution density of the inclusions having an average size of 300nm or more is 0.02 pieces / mm ² or more, the fraction of <100> / / ND It is characterized by the above-mentioned 18% or more and the Vickers hardness Hv1 of 190 or less.

Method for producing a non-oriented electrical steel sheet of the present invention for solving the above problems by weight, Al: 1.0 ~ 3.0%, Si: 0.5 ~ 2.5%, Mn: 0.5 ~ 2.0%, N: 0.001 ~ 0.004%, S : 0.0005 to 0.004%, remainder Fe and other unavoidably mixed impurities, Al, Mn, N, S is {[Al] + [Mn]} ≤3.5, 0.002≤ {[N] + [S] } ≤0.006, 300≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,400 The slab contained is heated to 1,100 ℃ or more, and then hot rolled to obtain hot finish. The rolling is carried out at 800 ° C. or higher, the hot rolled hot rolled sheet is annealed at a temperature range of 850 to 1,100 ° C., or the hot rolled sheet is annealed, pickled, and then cold rolled at a reduction ratio of 70 to 95%. The final cold annealing of the cold rolled cold plate in the temperature range of 750 ~ 1,100 ℃, characterized in that the temperature increase rate during the final annealing to 15 ~ 30 ℃ / s.

In the method for producing a non-oriented electrical steel sheet of the present invention, Al, Si, Mn is 1.7≤ {[Al] + [Si] + [Mn] / 2} ≤5.5, 0.6≤ [Al] / [Si] ≤ 4.0, 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.

In the manufacturing method of the non-oriented electrical steel sheet of the present invention is added to 0.3 ~ 0.5% Al to be deoxidized, and then the remaining alloy element is added, after the addition of the remaining alloy element to maintain the temperature of the molten steel to 1,500 ~ 1,600 ℃ Manufacturing the slab is another feature.

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 magnetic walls are improved, and the magnetic properties are excellent. High quality non-oriented electrical steel sheets having very 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.
Figure 3 is a view showing the texture and the texture structure disadvantageous to the magnetic advantage.
Figure 4 is a view showing the orientation distribution function (ODF) obtained by observing the cross-section (TD direction) of non-oriented electrical steel sheet by EBSD (Electron back scattered diffraction) for the purpose of examining the texture.

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.

The present invention is by weight, Al: 1.0 ~ 3.0%, Si: 0.5 ~ 2.5%, Mn: 0.5 ~ 2.0%, N: 0.001 ~ 0.004%, S: 0.0005 ~ 0.004%, balance Fe and other unavoidably incorporated It is composed of impurities, and Al, Mn, N, and S are {[Al] + [Mn]} ≤3.5, 0.002≤ {[N] + [S]} ≤0.006, 300≤ {([Al] + [Mn ]) / ([N] + [S])} ≤1,400, 1.7≤ {[Al] + [Si] + [Mn] / 2} ≤5.5, 0.6≤ [Al] / [Si] ≤4.0, 1≤ By containing so as to satisfy the composition formula of [Al] / [Mn] ≤8, the distribution density of nitrides and sulfides having an average size of 300 nm or more or inclusions thereof is increased to 0.02 pieces / mm ² or more. Accordingly, it is possible to manufacture the highest quality non-oriented electrical steel sheet having excellent machinability due to its excellent magnetic properties and low hardness of 190 Vickers hardness (Hv1) 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 final cold annealing of the cold rolled cold plate at a temperature range of 750 to 1,100 ° C., but the temperature increase rate at the time of final annealing is 15 to 30 ° C. / It is characterized by producing a non-oriented electrical steel sheet having excellent magnetic properties and workability by improving the cube texture fraction in the cross section of the steel sheet to 3% or more as s.

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: 1.0-3.0 wt%]

Al is added because it increases the specific resistance of the material, lowers iron loss and forms nitride, and is added in 1.0 to 3.0% to form coarse nitride. If the Al content is less than 1.0%, the inclusions cannot be sufficiently grown. If the Al content is more than 3.0%, the workability is degraded and problems occur in all processes such as steelmaking and continuous casting.

[Si: 0.5-2.5 wt%]

Si serves to lower the iron loss by increasing the specific resistance of the material, it is difficult to expect the iron loss reduction effect when contained less than 0.5%, productivity and punchability is inferior due to the increase in the hardness of the material when contained above 2.5%.

[Mn: 0.5-2.0 wt%]

Mn contains more than 0.5% because it increases the specific resistance of the material to improve iron loss and form sulfides, and when it contains more than 2%, it promotes the formation of [111] aggregates, which is disadvantageous to magnetism. Preferably limited to ˜2.0%.

[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 3.5% or less, which means that if the total amount of Al and Mn exceeds 3.5%, the fraction of the [111] aggregate tissue, which is disadvantageous to magnetism, increases and the magnetic Because it gets feverish. When the total amount of Al and Mn is less than 1.5%, nitrides, sulfides, or both complex inclusions are not coarse to form magnetic heat. However, in the present invention, Al is contained in an amount of 1.0% or more, and Mn is 0.5% or more. Since the total amount of Al and Mn is 1.5% 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 300≤ ([Al] + [Mn]) / ([N] + [S]) ≤1,400. 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 3.5% 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) in which ([Al] + [Mn]) / ([N] + [S]) is 300 to 1,400, the ratio of the total amount of Mn to the total amount of N and S, inclusions 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 0.6 ~ 4.0. This is because when the ratio of Al to Si is 0.6 to 4.0, the grain growth is excellent and the hardness of the material is lowered, thereby improving productivity and punchability. If [Al] / [Si] is less than 0.6, the inclusions do not grow significantly, resulting in poor growth of the crystal grains and thermal deterioration of magnetic properties. If [Al] / [Si] exceeds 4.0, the texture of the material will deteriorate, causing the magnetic flux density to heat up.

[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 alloying component related to a specific resistance (intrinsic resistance) is demonstrated. Recently, as the demand for eco-friendly cars is rapidly increasing, the demand for non-oriented electrical steel sheets that can be used for motors of eco-friendly cars is also increasing. The motor used in such an eco-friendly vehicle should increase the number of revolutions significantly. As the number of revolutions increases, the ratio of the eddy current loss among the iron core losses of the motor increases. To reduce this eddy current loss, the resistivity must be increased to 32 or more. However, if the resistivity exceeds 75, the addition amount of the alloying element should be increased, so that the workability is poor and the production cannot be performed by the conventional method. Therefore, it is appropriate to manage the resistivity between 32 and 75.

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 1.7 ~ 5.5% to satisfy specific resistance 32 ~ 75.

Hereinafter, a method of manufacturing a non-oriented electrical steel sheet according to the present invention. In the method for producing a non-oriented electrical steel sheet according to the present invention, it is preferable to first add 0.3 to 0.5% of the total Al content in the steelmaking step, and then add residual alloy elements to sufficiently deoxidize the steel. After the alloying element is added, the molten steel is maintained at a temperature of 1,500 to 1,600 ° C. so that the inclusions in the steel are sufficiently grown, and then solidified in a continuous casting process to manufacture the 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 annealing or omitting the hot rolled sheet as described above, the hot rolled sheet is pickled and cold rolled to a predetermined sheet thickness. Cold rolling can be performed at a rolling reduction of about 70-95%. In the present invention, the addition amount of the alloying elements of Si, Mn, Al, P affecting the cold rolling is appropriately adjusted, and thus the cold rolling is excellent. Therefore, a high rolling rate can be applied. It can be manufactured in thin plates. 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. In the final annealing, it is advantageous to improve the magnetism so that the grain size is 70 to 150 μm. If the final annealing temperature is less than 750 ℃ recrystallization does not occur sufficiently, if the final annealing temperature exceeds 1,100 ℃ the surface layer oxide layer is deeply formed and the magnetism is lowered, so the final annealing is preferably performed within the temperature range of 750 ~ 1,100 ℃ Do.

The temperature increase rate up to the cracking temperature at the final annealing should be 15 ~ 30 ℃ / s. If the temperature increase rate is less than 15 ℃ / s, the fraction of the aggregate structure in which the <111> // ND, ie, the <001> plane, which is unfavorable to magnetism, is parallel to the vertical direction of the steel sheet (ND), and the temperature increase rate is 30. This is because the process cost is excessively increased when it exceeds the ℃ / s.

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. The contents of impurities C, S, N, and Ti of the material were controlled to 0.002%, respectively, and 0.3 to 0.5% of Al was added to the molten steel to promote the formation of inclusions, and then the remaining Al, Si, and Mn were added to the steel ingot. Prepared. Each material was heated to 1,150 캜 and hot-rolled at 850 캜 to produce a hot-rolled sheet having a thickness of 2.0 mm. The hot rolled hot rolled sheet was annealed at 1,050 ° C. for 4 minutes and then pickled. Thereafter, cold rolling was performed to make the plate thickness 0.35 mm, followed by final annealing for 38 seconds at 1,050 ° C.

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 3.0 0.5 1.0 0.002 0.002 0.002 0.002 A2 2.5 0.5 1.0 0.002 0.002 0.002 0.002 A3 1.0 0.5 1.0 0.002 0.002 0.002 0.002 A4 3.0 1.0 1.0 0.002 0.002 0.002 0.002 A5 2.0 1.0 1.0 0.002 0.002 0.002 0.002 A6 1.0 1.0 1.0 0.002 0.002 0.002 0.002 A7 0.5 1.0 1.0 0.002 0.002 0.002 0.002 A8 3.5 1.5 1.0 0.002 0.002 0.002 0.002 A9 2.5 1.5 1.0 0.002 0.002 0.002 0.002 A10 1.5 1.5 1.0 0.002 0.002 0.002 0.002 A11 3.0 2.0 1.0 0.002 0.002 0.002 0.002 A12 1.5 2.0 1.0 0.002 0.002 0.002 0.002 A13 3.0 2.5 1.0 0.002 0.002 0.002 0.002 A14 2.5 2.5 1.0 0.002 0.002 0.002 0.002 A15 1.0 2.5 1.0 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;
W / Kg) Magnetic flux
density
(B50;
Tesla) Hardness
(Hv1) Remarks A1 6.0 3.0 4.0 0.0040 1000 4.0 250 0 2.2 1.62 165 Comparative example A2 5.0 2.5 3.5 0.0040 875 3.5 200 0 2.3 1.62 160 Comparative example A3 2.0 1.0 2.0 0.0040 500 2.0 300 0.02 2.5 1.72 140 Honor A4 3.0 3.0 4.0 0.0040 1000 4.5 250 0 2.4 1.62 157 Comparative example A5 2.0 2.0 3.0 0.0040 750 3.5 500 0.07 2.0 1.67 155 Honor A6 1.0 1.0 2.0 0.0040 500 2.5 450 0.05 2.1 1.68 150 Honor A7 0.5 0.5 1.5 0.0040 375 2.0 50 0 2.5 1.66 145 Comparative example A8 2.3 3.5 4.5 0.0040 1125 5.5 75 0 2.5 1.64 190 Comparative example A9 1.7 2.5 3.5 0.0040 875 4.5 400 0.05 2.0 1.67 185 Honor A10 1.0 1.5 2.5 0.0040 625 3.5 600 0.08 2.0 1.68 170 Honor A11 1.5 3.0 4.0 0.0040 1000 5.5 250 0 2.3 1.62 195 Comparative example A12 0.8 1.5 2.5 0.0040 625 4.0 400 0.04 2.0 1.68 183 Honor A13 1.2 3.0 4.0 0.0040 1000 6.0 75 0 2.0 1.61 210 Comparative example A14 1.0 2.5 3.5 0.0040 875 5.5 400 0.03 1.9 1.65 190 Honor A15 0.4 1.0 2.0 0.0040 500 4.0 60 0 2.4 1.67 195 Comparative example

In the case of steel grades A3, A5, A6, A9, A10, A12, and A14 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 density is 0.02 It is higher than 1 / mm ² ) and its magnetic property is excellent.

On the other hand, in steel type A1, an inclusion having an Al / Si ratio and Al + Mn outside the scope of the present invention having a size of 300 nm or more was not observed, and iron loss and magnetic flux density were inferior. In steel grades A2 and A15, inclusions having a size of 300 nm or more out of the Al / Si ratio were not observed, and iron loss and magnetic flux density were inferior. For steel grades A4, A8, A11, and A13, inclusions having a size of 300 nm or more outside Al + Mn were not observed, and iron loss and magnetic flux density were inferior. In the steel grade A7, inclusions having a size of 300 nm or more out of the ratio of Al / Si and Al / Mn 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 3 below. The ingredients were adjusted while varying the content of impurities N and S of the material, and the Al was added to the molten steel by 0.3-0.5% to promote inclusion formation. Then, the remaining Al, Si, and Mn were added to prepare the steel ingot. . Each material was heated to 1,150 캜 and hot-rolled at 850 캜 to produce a hot-rolled sheet having a thickness of 2.0 mm. The hot rolled hot rolled sheet was annealed at 1,050 ° C. for 4 minutes and then pickled. Thereafter, cold rolling was performed to make the plate thickness 0.35 mm, followed by final annealing for 38 seconds at 1,050 ° C.

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 0.5 0.002 0.001 0.001 0.002 B2 1.0 0.5 0.5 0.002 0.003 0.003 0.002 B3 1.0 0.5 0.5 0.002 0.0005 0.001 0.002 B4 1.0 0.5 1.0 0.002 0.002 0.003 0.002 B5 1.2 0.5 1.2 0.002 0.0015 0.002 0.002 B6 1.2 0.5 1.0 0.002 0.0005 0.0005 0.002 B7 1.2 0.5 1.0 0.002 0.003 0.003 0.002 B8 2.0 0.5 2.0 0.002 0.001 0.003 0.002 B9 2.0 0.5 1.5 0.002 0.001 0.0015 0.002 B10 2.0 0.5 1.5 0.002 0.001 0.003 0.002 B11 2.0 0.5 1.0 0.002 0.003 0.004 0.002 B12 2.0 1.0 1.5 0.002 0.0005 0.0015 0.002 B13 2.0 1.0 1.5 0.002 0.002 0.004 0.002 B14 1.5 1.0 1.5 0.002 0.002 0.0025 0.002 B15 2.5 1.0 1.0 0.002 0.0005 0.0005 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;
W / Kg) Magnetic flux density
(B50;
Tesla) Hardness
(Hv1) Remarks B1 2.0 2.0 1.5 0.0020 750 1.8 350 0.03 2.6 1.74 135 Honor B2 2.0 2.0 1.5 0.0060 250 1.8 75 0 3.2 1.72 135 Comparative example B3 2.0 2.0 1.5 0.0015 1000 1.8 120 0 2.9 1.71 135 Comparative example B4 2.0 1.0 2.0 0.0050 400 2.0 400 0.04 2.6 1.70 140 Honor B5 2.4 1.0 2.4 0.0035 686 2.3 450 0.03 2.2 1.69 150 Honor B6 2.4 1.2 2.2 0.0010 2200 2.2 50 0 2.4 1.67 150 Comparative example B7 2.4 1.2 2.2 0.0060 367 2.2 350 0.02 2.3 1.70 165 Honor B8 4.0 1.0 4.0 0.0040 1000 3.5 250 0 2.3 1.62 185 Comparative example B9 4.0 1.3 3.5 0.0025 1400 3.3 450 0.05 2 1.67 170 Honor B10 4.0 1.3 3.5 0.0040 875 3.3 550 0.08 2 1.68 170 Honor B11 4.0 2.0 3.0 0.0070 429 3.0 250 0 2.2 1.65 170 Comparative example B12 2.0 1.3 3.5 0.0020 1750 3.8 80 0 2.3 1.65 165 Comparative example B13 2.0 1.3 3.5 0.0060 583 3.8 500 0.07 2 1.68 175 Honor B14 1.5 1.0 3.0 0.0045 667 3.3 600 0.07 2 1.68 170 Honor B15 2.5 2.5 3.5 0.0010 3500 4.0 50 0 2.2 1.65 165 Comparative example

Steel grades B1, B4, B5, B7, B9, B10, B13, and B14, 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 managed 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 B3, B6, B11, and B15, inclusions having a size 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. For steel grade B8, Al + Mn is out of the scope of the present invention and for steel grades B2, B12, (Al + Mn) / (N + S) is out of the scope of the present invention, no coarse inclusions having a size of 300 nm or more were observed. 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, 0.3 to 0.5% of Al was added to the molten steel to promote formation of inclusions, and then Al, Si, and Mn were added to prepare a steel ingot. Each material was heated to 1,150 캜 and hot-rolled at 850 캜 to produce a hot-rolled sheet having a thickness of 2.0 mm. The hot rolled hot rolled sheet was annealed at 1,050 ° C. for 4 minutes and then pickled. Thereafter, cold rolling was performed to make the plate thickness 0.35 mm, and final annealing was performed at 1,050 ° C. for 38 seconds so that the grain size was 70-100 μm. The temperature increase rate at the final annealing was varied as shown in Table 6. For each sample thus obtained, the cube texture fraction, <100> // ND fraction, iron loss and magnetic flux density were measured and shown in Table 6. The fraction of the aggregates was determined from the values including grains corresponding to the small-angle boundary within 15 °.

Steel grade Al Si Mn C S N Ti C1 1.5 1.5 1.0 0.002 0.002 0.002 0.002 C2 1.5 1.5 1.0 0.002 0.002 0.002 0.002 C3 1.5 1.5 1.0 0.002 0.002 0.002 0.002 C4 1.5 1.5 1.0 0.002 0.002 0.002 0.002 C5 1.0 1.0 1.0 0.002 0.002 0.002 0.002 C6 1.0 1.0 1.0 0.002 0.002 0.002 0.002 C7 1.0 1.0 1.0 0.002 0.002 0.002 0.002 C8 1.0 1.0 1.0 0.002 0.002 0.002 0.002 C9 2.0 1.0 1.0 0.002 0.002 0.002 0.002 C10 2.0 1.0 1.0 0.002 0.002 0.002 0.002 C11 2.0 1.0 1.0 0.002 0.002 0.002 0.002 C12 2.0 1.0 1.0 0.002 0.002 0.002 0.002 C13 3.0 2.0 1.0 0.002 0.002 0.002 0.002 C14 3.0 2.0 1.0 0.002 0.002 0.002 0.002 C15 3.0 2.0 1.0 0.002 0.002 0.002 0.002 C16 3.0 2.0 1.0 0.002 0.002 0.002 0.002

Steel grade Al / Si Al / Mn Al + Mn N + S (Al + Mn)
/ (N + S) Heating
speed
(℃ / sec) Cube
Fraction
(%) <100>
// ND
Fraction (%) Iron loss
(W15 / 50;
W / Kg) Magnetic flux density
(B50;
Tesla) Remarks C1 1.0 1.5 2.5 0.0040 625 10 2.5 18 2.0 1.68 Comparative example C2 1.0 1.5 2.5 0.0040 625 20 3.1 21 2.0 1.68 Honor C3 1.0 1.5 2.5 0.0040 625 25 3.3 23 1.9 1.68 Honor C4 1.0 1.5 2.5 0.0040 625 30 3.5 25 1.9 1.68 Honor C5 1.0 1.0 2.0 0.0040 500 10 2.8 17 2.1 1.68 Comparative example C6 1.0 1.0 2.0 0.0040 500 20 3.2 19 2.1 1.68 Honor C7 1.0 1.0 2.0 0.0040 500 25 3.5 21 2.0 1.68 Honor C8 1.0 1.0 2.0 0.0040 500 30 3.9 20 2.0 1.68 Honor C9 2.0 2.0 3.0 0.0040 750 10 2.8 20 2.0 1.67 Comparative example C10 2.0 2.0 3.0 0.0040 750 20 3.2 22 2.0 1.67 Honor C11 2.0 2.0 3.0 0.0040 750 25 3.7 25 1.9 1.67 Honor C12 2.0 2.0 3.0 0.0040 750 30 4.0 23 2.0 1.67 Honor C13 1.5 3.0 4.0 0.0040 1000 10 2.3 17 2.3 1.62 Comparative example C14 1.5 3.0 4.0 0.0040 1000 20 2.5 18 2.2 1.63 Comparative example C15 1.5 3.0 4.0 0.0040 1000 25 2.2 17 2.2 1.63 Comparative example C16 1.5 3.0 4.0 0.0040 1000 30 2.8 18 2.2 1.64 Comparative example

Steel grades C2 to C4, C6 to C8, and C10 to C12 having the final annealing heating rate controlled at the range of 15 to 30 ° C / sec of the present invention have a fraction of cube aggregates of 3.0% or more and a <100> // ND fraction. At 18% or more, the magnetism was also excellent.

Steel grades C1, C5, and C9 whose final annealing temperature increase rate is outside the scope of the present invention have a fraction of the cube texture less than 3.0%, inferior in magnetic properties. Steel grades C13-16 were Al + Mn out of the scope of the present invention, the fraction of the cube texture is less than 3.0%, magnetic inferior.

4 is a diagram showing the orientation distribution function (ODF) obtained by observing the cross section of the steel sheet (TD direction) by EBSD (Electron back scattered diffraction). It is shown schematically in the section of Ф2 = 45 ° in the ODF.

The reason for obtaining the ODF from the aggregated tissue data is to quantitatively analyze the observed aggregated structure, and the F2 = 45 ° section in the ODF indicates that Cube ({001} <100 is a representative aggregated structure of metal with a body-centered cubic structure. This is because the Rotated Cube ({001} <110>), α-fiber (<110> // RD), and γ-fiber (<111> // ND) can be represented. The position of the texture shown in FIG. 4 is an ideal position, and the contour lines are used to express the strength of the texture, and a general tolerance is within 15 °.

In the non-oriented electrical steel sheet, the larger the fraction of <100> // ND including the cube ({001} <100>) and the rotated cube ({001} <110>) textures, the better the magnetic properties. On the other hand, since α-fiber (<110> // RD) and γ-fiber (<111> // ND) include magnetization difficulty axes that are not easily magnetized, the lower the fraction, the better the magnetic properties.

From the illustration of Figure 4, it can be seen that the maximum strength of the texture of the non-oriented electrical steel sheet of the present invention is higher than the maximum strength of the texture of the comparative example deviating from the scope of the present invention. From this, it can be seen that the non-oriented electrical steel sheet of the present invention has a large number of textures, particularly cube textures, which are advantageous for magnetic properties during grain growth, and thus have excellent magnetic properties.

Claims (14)

By weight%, Al: 1.0-3.0%, Si: 0.5-2.5%, Mn: 0.5-2.0%, N: 0.001-0.004%, S: 0.0005-0.004%, C: 0.004% or less, Ti: 0.004% or less , Remainder Fe and other unavoidable impurities, Al, Mn, N, S, Si is contained so as to satisfy the composition formula of the following conditional formulas 1 to 6, the fraction of the cube texture of the cross-section is 3% or more Non-oriented electrical steel sheet with excellent magnetic properties.
{[Al] + [Mn]} ≤3.5 --------------------- Conditional Expression 1
0.002≤ {[N] + [S]} ≤0.006 --------------------- Conditional Expression 2
300≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,400 --------------------- Conditional Expression 3
1.7≤ {[Al] + [Si] + [Mn] / 2} ≤5.5 --------------------- Conditional Expression 4
0.6≤ [Al] / [Si] ≤4.0 --------------------- Conditional Expression 5
1≤ [Al] / [Mn] ≤8 --------------------- Conditional Expression 6
[Al], [Mn], [N], [S], and [Si] mean content (wt%) of Al, Mn, N, S, and Si, respectively. delete delete The method according to claim 1,
Non-oriented electrical steel sheet with excellent magnetic properties with Vickers hardness (Hv1) of 190 or less. 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 fraction of <100> // ND of 18% or more.
The <100> // ND means an aggregate structure in which the <001> plane is placed parallel to the vertical direction of the steel sheet. delete The method according to claim 5,
Non-oriented electrical steel sheet having excellent magnetic properties with a fraction of <100> // ND of 18% or more.
The <100> // ND means an aggregate structure in which the <001> plane is placed parallel to the vertical direction of the steel sheet. By weight%, Al: 1.0-3.0%, Si: 0.5-2.5%, Mn: 0.5-2.0%, N: 0.001-0.004%, S: 0.0005-0.004%, C: 0.004% or less, Ti: 0.004% or less , Remainder Fe and other unavoidable impurities, Al, Mn, N, S, Si is {[Al] + [Mn]} ≤3.5, 0.002≤ {[N] + [S]} ≤0.006 , 300≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,400, 1.7≤ {[Al] + [Si] + [Mn] / 2} ≤5.5, 0.6≤ [ The slab contained to satisfy the composition formula of Al] / [Si] ≤4.0, 1≤ [Al] / [Mn] ≤8 was heated to a temperature of 1,100 ~ 1,250 ° C, and then hot rolled, but hot finishing rolling was performed at 800 ° C or higher. The hot rolled hot rolled sheet is annealed at a temperature range of 850 to 1,100 ° C., or the hot rolled sheet is annealed, followed by pickling, followed by cold rolling at a reduction ratio of 70 to 95%, and cold rolled cold rolled sheet. The final annealing in the temperature range of 750 ~ 1,100 ℃, a method of producing a non-oriented electrical steel sheet having excellent magnetic properties of the temperature increase rate at the time of final annealing 15 ~ 30 ℃ / s.
[Al], [Mn], [N], [S], and [Si] mean content (wt%) of Al, Mn, N, S, and Si, respectively. delete delete The method according to claim 9,
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. The method according to claim 9,
A method of manufacturing non-oriented electrical steel sheet having excellent magnetic properties by controlling the fraction of cube aggregate of cross section to 3% or more and controlling the fraction of <100> // ND to 18% or more.
The <100> // ND means an aggregate structure in which the <001> plane is placed parallel to the vertical direction of the steel sheet. The method according to claim 9,
After the addition of 0.3 ~ 0.5% of Al to deoxidize, the remaining alloying elements are added, and after the addition of the remaining alloying elements, the temperature is maintained at 1,500 ~ 1,600 ℃ to manufacture the excellent magnetic non-oriented electrical steel sheet for producing slabs. Way.

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