KR20110075521A - Non-oriented electrical steel sheet with excellent magnetic property, and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A non-oriented electric steel sheet and a manufacturing method thereof are provided to improve the growing ability of grains by increasing the density of coarse inclusion in steel and reducing the generation frequency of fine inclusion. CONSTITUTION: A slab is heated to a temperature of 1,100-1,250°C and the heated slab is hot-rolled where finish hot-rolling is implemented at a temperature of 800°C or higher. The hot-rolled plate is processed in a batch annealing furnace at a temperature of 850-1,100°C and cold-rolled at a reduction ratio of 70-95wt%. The cold-rolled plate is finally annealed at a temperature of 750-1,100°C. Al of 0.3~0.5% is added for deoxidation. The slab comprises Al: 1.0~3.0wt%, Si: 0.5~2.5wt%, Mn: 0.5~2.0wt%, N: 0.001~0.004wt%, S: 0.0005~0.004wt%, P: 0.2wt% or less, and the remaining amount of Fe and impurities.

Description

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

The present invention relates to the production of non-oriented electrical steel sheet, by increasing the distribution density of coarse inclusions in the steel by optimally setting the additive component of the steel to improve the grain growth and the mobility of the magnetic wall has excellent magnetic properties, low hardness It relates to a high-quality non-oriented electrical steel sheet excellent in product productivity and punchability and a manufacturing method thereof.

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. On the other hand, when the Si addition amount increases, the magnetic flux density decreases, and when the addition amount exceeds 3%, the workability is lowered and cold rolling becomes difficult. 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 amount of Si added and increasing the amount of Al added. Japanese Patent Laid-Open Publication Nos. 2001-059145, 2001-073098, and the like, but have not yet been put to practical use due to the difficulty in securing the magnetic properties of high-quality non-oriented electrical steel sheets and the 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 (C, S, N, Ti, etc.) such as fine inclusions in the steel extremely low to improve the growth of crystal grains. However, it is difficult to manage impurities very low in the manufacturing process of ordinary steel sheet, and impurities not removed in the steelmaking stage exist in the form of nitrides or sulfides in the slab during continuous casting, and the slabs for hot rolling. When reheated to a temperature of 1,100 ℃ or more, inclusions such as nitrides and sulfides are re-dissolved and then finely precipitated again at the end of hot rolling. 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 general manufacturing process of the non-oriented electrical steel sheet, impurities are properly controlled from the steelmaking stage so that such fine inclusions do not exist, and the remaining inclusions are re-used during hot rolling to suppress the finer precipitation. Japanese Laid-Open Patent Publication No. 2006-124800 proposes a method of adding REM, but has a disadvantage in that an increase in cost occurs in the steelmaking step due to extremely low control of impurities.

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

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%, P: 0.2% or less, the balance Fe and other inevitable impurities are added, Al, Mn, N, S is characterized in that it is added so as to satisfy the composition formula of the following condition formulas 1-3.

1.5≤ {[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] are the amounts of Al, Mn, N, and S added (% by weight), respectively.

Non-oriented electrical steel sheet of the present invention is characterized in that the Al, Si, Mn is added 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] is the amount of Si added (% by weight)

The 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%, P: 0.2 % Or less, remainder Fe and other inevitable addition 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 do.

The non-oriented electrical steel sheet of the present invention has a Vickers hardness (Hv1) of 190 or less, an average grain size of 170 µm or less, a magnetic flux density (B50) of 1.60 to 1.70T, and an iron loss (W10 / 400) of 9.0 to 19.0 W / kg. It is characterized by.

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%, P: 0.2% or less, remainder Fe and other unavoidably added impurities, Al, Mn, N, S is 1.5≤ {[Al] + [Mn]} <3.5, 0.002≤ {[N] + [S]} ≤0.006, 300≤ {([Al] + [Mn]) / ([N] + [S])} ≤1,400 Composition Formulas [[Al], [Mn], [N ], [S] is the slab added to satisfy the addition amount of Al, Mn, N, S, respectively, to be heated to 1,100 ℃ or more and hot-rolled, hot finishing rolling is carried out at 800 ℃ or more, hot rolled hot plate In the temperature range of 850 ~ 1,100 ℃ hot rolled sheet annealing or omitting the hot rolled sheet annealing, pickling, cold rolled at a reduction ratio of 70 ~ 95%, cold rolled cold rolled sheet is a temperature range of 750 ~ 1,100 ℃ Characterized in that the final annealing at.

In the method for producing a non-oriented electrical steel sheet of the present invention Al, Si, Mn in the slab composition formula 1.7≤ {[Al] + [Si] + [Mn] / 2} ≤5.5, 0.6≤ [Al] / [Si] It is characterized by being added so as to satisfy the composition formula ([Si] is Si added amount) of ≤4.0, 1≤ [Al] / [Mn] ≤8.

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 alloy 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 grains and the mobility of the magnetic walls are improved, and the highest quality has low hardness. Non-oriented electrical steel sheet can be produced. In addition, the customer's processability and productivity is excellent, and the cost is reduced by lowering the production cost of the product.

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, the amounts of Al, Si, Mn and impurity elements N and S are appropriately controlled, 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: 1.0-3.0%, Si: 0.5-2.5%, Mn: 0.5-2.0%, P: 0.2% or less, N: 0.001-0.004%, S: 0.0005-0.004%, balance Fe And other inevitable impurities, wherein Al, Mn, N, and S are 1.5 ≦ {[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] / Composition formulas of [Si] ≤4.0, 1≤ [Al] / [Mn] ≤8 ([Al], [Si], [Mn], [N], [S] are Al, Si, Mn, N, S, respectively) By adding so as to satisfy the (a), the distribution density of nitrides and sulfides having an average size of 300 nm or more or inclusions including them is increased to 0.02 pieces / mm ² or more, and thus the cross-sectional Vickers hardness (Hv1) Due to the low hardness of 190 or less, it has excellent workability, and produces the highest quality non-oriented electrical steel sheet with average grain size of 170㎛ or less, magnetic flux density (B50) of 1.60 ~ 1.70T, iron loss (W10 / 400) of 9.0 ~ 19.0W / kg. can do.

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 and Mn, Si, N, and S were added to satisfy specific conditions, a huge complex inclusion composed of nitrides or sulfides was formed, and the processability was adjusted by adjusting the distribution density of such composite inclusions. Despite the addition of a minimum amount of deteriorating alloying elements, the present invention has been proposed based on the fact that the magnetism is greatly improved.

First, the reason for limiting the range of component elements constituting the present invention and the addition ratio between the component elements 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 Al is added less than 1.0%, the inclusions cannot be grown sufficiently, and if it is added more than 3.0%, the workability is deteriorated and problems occur in all processes such as steelmaking and continuous casting, so that it cannot be produced in a normal process.

[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 effect of reducing iron loss when added to less than 0.5%, productivity and punchability is inferior due to the increase of the hardness of the material when added more than 2.5%.

[Mn: 0.5-2.0 wt%]

Mn increases the specific resistance of the material to improve iron loss and form sulfides. Therefore, Mn is added in an amount of 0.5% or more. When Mn is added in excess of 2%, Mn promotes the formation of [111] aggregates, which is disadvantageous to magnetism. Preferably limited to ˜2.0%.

[P: 0.2 wt% or less]

When added to 0.2% or less, P forms an advantageous texture for magnetism, improves in-plane anisotropy and improves workability. However, if it is added in excess of 0.2%, cold rolling property is lowered and workability worsens, so it is limited to 0.2% or less.

[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, and thus it is not economical. Therefore, as described below, it is possible to actively grow the inclusions by using an element having a large affinity with N, which is an impurity element, for grain growth. 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%. If N exceeds 0.004%, coarsening of inclusions is not achieved, and iron loss is increased, and more preferably, N is added to 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, and more preferably S is added to 0.003% or less.

[C: 0.002-0.004 wt%]

Since C causes self aging, it is limited to 0.004% or less, preferably 0.003% or less.

In addition to the above impurity elements, impurities such as Ti, which are inevitably added, may also be included. Ti promotes the growth of [111], which is an undesirable crystal orientation in the non-oriented electrical steel sheet, so it is limited to 0.004% or less, more preferably 0.003% or less.

In the present invention, the total amount of Al and Mn [Al] + [Mn] is limited to 1.5 ~ 3.5%, which is not formed coarse nitride, sulfide or two complex inclusions when the total amount of Al and Mn is less than 1.5% This is because the magnetism is inferior, and when the total amount of Al and Mn exceeds 3.5, the fraction of the [111] aggregate structure, which is disadvantageous to magnetism, increases, causing the magnetism to deteriorate.

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 added so as to satisfy the composition formula of 300≤ ([Al] + [Mn]) / ([N] + [S]) ≤1,400. [Al], [Mn], [N], and [S] mean an addition amount (% by weight) 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 addition amount of Al, Mn, N, and S is optimally managed, the inclusions grow more than several times as compared to the conventional materials, resulting in a high 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.

2, [Al] + [Mn], which is the total amount of Al and Mn, is 1.5 to 3.5%, and [N] + [S], which is the total amount of N and S, is 0.002 to 0.006. In the range of the present invention where ([Al] + [Mn]) / ([N] + [S]) is a ratio of the total amount of N and S to the total amount of N and S, the inclusions are coarsened and the average size While the distribution density of the large composite inclusions having a diameter of 300 nm or more is higher than 0.02 pieces / mm ² , the magnetic properties are excellent, whereas in the range outside the present invention, the coarse inclusions are not formed and the distribution density of the large composite inclusions having an average size of 300 nm or more is 0.02 pieces / It is lower than mm ² and the magnetism is degraded because the texture is inferior.

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 alloy component related to a specific 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 precipitates that spoil the magnetic can be re-dissolved and precipitated finely 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 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.

Cold rolled cold rolled plates are 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, the magnetic deterioration 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.

Example 1

The ingot of the components shown in Table 1-1 below was prepared by vacuum dissolution in a laboratory. 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, Mn, and P were added thereto. Ingots were prepared. Each material was heated to 1,150 ° C. and hot-rolled at 850 ° C. 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 were measured and shown in Table 1-2.

Table 1-1

Table 1-2

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. Steel grades A4, A8, A11, and A13 were found to have Al + Mn outside the scope of the present invention, and no inclusions having a size of 300 nm or more were inferior in iron loss and magnetic flux density. 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.

Example 2

Vacuum dissolution was carried out in the laboratory to prepare ingots of the components shown in Table 2-1 below. The ingredients were adjusted while varying the contents of impurities N and S of the material, and Al was added to the molten steel by 0.3-0.5% to promote inclusion formation, and then the remaining Al, Si, Mn, and P were added to the steel ingot. Prepared. Each material was heated to 1,150 ° C. and hot-rolled at 850 ° C. 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 were measured and shown in Table 2-2.

Table 2-1

Table 2-2

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. In steel B8, 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.

Example 3

Vacuum dissolution was carried out in the laboratory to prepare ingots of the components shown in Table 3-1 below. After adding 0.3 to 0.5% of Al to the molten steel to promote the formation of inclusions, the remaining Al, Si, Mn, and P were added to prepare a steel ingot. Each material was heated to 1,150 ° C. and hot-rolled at 850 ° C. 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 form various plate thicknesses of 0.15 to 0.35 mm, followed by final annealing at 1,050 ° C. for 38 seconds. Iron loss and magnetic flux density of each plate were measured and shown in Table 3-2.

Table 3-1

Table 3-2

Steel grades C2 to C7 belonging to the scope of the present invention have high magnetic flux density and low iron loss. This is considered to be because the inclusions grow coarsely in the component system of the present invention, the distribution density of the huge composite inclusions is formed higher than 0.02 (1 / mm ² ), and the aggregate structure is stabilized.

On the other hand, in the case of steel C1, Al + Mn and Al / Si were out of the scope of the present invention, and the iron loss (W10 / 400) and the magnetic flux density (B50) were inferior.

The high frequency iron loss (W10 / 400) has a clear correlation with the steel plate thickness, so the thickness is thinner, and the characteristics are improved. In contrast to the 0.35mm thickness, the steel loss of 0.15mm thickness is improved by 50% or more.

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.

Claims (11)

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%, P: 0.2% or less, balance Fe and other unavoidable A non-oriented electrical steel sheet having excellent magnetic properties, wherein the Al, Mn, N, and S are added to satisfy the compositional formulas of Conditional Formulas 1 to 3 below. 1.5≤ {[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 addition amounts (wt%) of Al, Mn, N, and S, respectively. The method according to claim 1, The Al, Si, Mn is a non-oriented electrical steel sheet having excellent magnetic properties added to satisfy the composition formula of the following condition 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 Said [Si] means the addition amount (weight%) of Si. 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. 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%, P: 0.2% or less, balance Fe and other unavoidable The non-oriented electrical steel sheet composed of impurities, which are added in a simple manner, includes nitride and sulfide alone or inclusions in which steel sheets are contained, and has a distribution density of 0.02 pieces / mm ² or more. The method according to any one of claims 1 to 4, Non-oriented electrical steel sheet with excellent magnetic properties with Vickers hardness (Hv1) of 190 or less. The method according to any one of claims 1 to 4, Non-oriented electrical steel sheet with excellent magnetic properties with an average grain size of 170㎛ or less. The method according to any one of claims 1 to 4, Non-oriented electrical steel sheet with excellent magnetic strength (B50) is 1.60 ~ 1.70T and iron loss (W10 / 400) is 9.0 ~ 19.0W / kg. 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%, P: 0.2% or less, balance Fe and other unavoidable Al, Mn, N, S are 1.5≤ {[Al] + [Mn]} <3.5, 0.002≤ {[N] + [S]} ≤0.006, 300≤ {([ Al] + [Mn]) / ([N] + [S])} ≤1,400 (where [Al], [Mn], [N], and [S] are the amounts of Al, Mn, N, and S added, respectively) The slab added to satisfy the temperature is heated to a temperature of 1,100 ~ 1,250 ℃ and then hot rolled, but the hot finish rolling is carried out at 800 ℃ or more, hot rolled hot rolled sheet in the temperature range of 850 ~ 1,100 ℃ or The method of manufacturing a non-oriented electrical steel sheet having excellent magnetic properties, omitting the hot rolled sheet annealing, pickling, cold rolling at a reduction ratio of 70 to 95%, and finally annealing the cold rolled cold sheet at a temperature range of 750 to 1,100 ° C. . [Al], [Mn], [N], and [S] mean addition amounts (wt%) of Al, Mn, N, and S, respectively. The method according to claim 8, The slab is Al, Si, Mn is a composition formula 1.7≤ {[Al] + [Si] + [Mn] / 2} ≤5.5, 0.6≤ [Al] / [Si] ≤4.0, 1≤ [Al] / [Mn ] Is a method for producing a non-oriented electrical steel sheet having excellent magnetic properties to be added so as to satisfy the composition formula ([Si] is the amount of Si added). Said [Si] means the addition amount (weight%) of Si. The method according to claim 8, 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 any one of claims 8 to 10, 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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