KR101329716B1 - 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: 1.0-3.0%, Si: 0.5-2.5%, Mn: 0.5-2.0%, Cu: 0.002-0.030%, N: 0.001-0.004%, S : 0.0005 to 0.004%, the balance Fe and other inevitable impurities are mixed, Al, Mn, N, S, Si is 1.5≤ (Al + Mn) ≤3.5, 0.002≤ (N + S) ≤0.006, It is contained so as to satisfy all of the conditions of 300≤ (Al + Mn) / (N + S) ≤1,400, 0.6≤Al / Si≤4.0, and the Cu is magnetic contained to satisfy the conditions of 1≤Cu / S≤14. This excellent non-oriented electrical steel sheet and its manufacturing method are provided. Accordingly, by increasing the distribution density of the coarse inclusions to improve grain growth and mobility of the magnetic walls, it is possible to stably manufacture the highest quality non-oriented electrical steel sheet having excellent magnetic properties and low hardness, and excellent customer processability and productivity.

Description

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

The present invention relates to a manufacturing technology of non-oriented electrical steel sheet, the additive component of the steel is set optimally, the distribution density of coarse inclusions in the steel is high, the growth of crystal grains and the mobility of the magnetic wall is improved, it is possible to secure excellent magnetic, The present invention relates to a high quality non-oriented electrical steel sheet and a method of manufacturing the same, which improves product productivity and punchability due to low hardness.

The present invention relates to the manufacturing technology of non-oriented electrical steel sheet mainly used as the iron core material of the rotating machine, the magnetic properties are very important because the non-oriented electrical steel sheet is used as an important component for converting electrical energy into mechanical energy . Mainly mentioned 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.

Typically, Si is added as a main element to produce a non-oriented electrical steel sheet having low iron loss. However, when the Si content is excessively high, the magnetic flux density of the non-oriented electrical steel sheet decreases, and when the Si content exceeds 3%, the workability is lowered, which makes cold rolling 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 Si content and increasing the Al content, 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 non-oriented electrical steel sheet, it is necessary to improve the grain growth by forming fine inclusions in the steel or controlling impurities such as C, S, N, Ti, and Cu, which adversely affect the magnetic properties. have. 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, CuS, 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 prevent the growth of grains during annealing, thereby increasing the hysteresis loss. In addition, the magnetization reduces the permeability by preventing the movement of the wall.

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 has been made to solve all the problems of the prior art as described above, by managing the ratio of the alloying elements of steel Al, Si, Mn, impurity elements N, S, Cu in the optimum conditions to By increasing the distribution density of the inclusions and reducing the frequency of occurrence of fine inclusions, it is possible to secure excellent magnetism by improving the growth of grains and the mobility of the magnetic walls, and the high-quality non-oriented electrical steel sheet with excellent productivity and punchability due to the low hardness characteristics. It is to provide.

The 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%, Cu: 0.002 ~ 0.030%, N: 0.001 ~ 0.004%, S: 0.0005% to 0.004%, balance Fe and other unavoidable impurities, and Al, Mn, N, S, and Si are 1.5≤ (Al + Mn) ≤3.5, 0.002≤ (N + S ) ≤ 0.006, 300 ≤ (Al + Mn) / (N + S) ≤ 1, 400, 0.6 ≤ Al / Si ≤ 4.0 is contained to satisfy all the conditions, the Cu meets the conditions of 1.0 ≤ Cu / S ≤ 14.0 It is characterized by being contained to.

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 conditions of 1.7≤ (Al + Si + Mn / 2) ≤5.5, 1≤Al / Mn≤8.

In the non-oriented electrical steel sheet of the present invention, nitrides and sulfides alone or composite inclusions are formed in the steel sheet, and the distribution density of the inclusions having an average size of 300 nm or more is 0.02 pieces / mm ² or more.

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%, Cu: 0.002 ~ 0.030%, N : 0.001% to 0.004%, S: 0.0005% to 0.004%, balance Fe and other inevitable impurities, and Al, Mn, N, S, and Si are 1.5≤ (Al + Mn) ≤3.5, 0.002≤ ( N + S) ≤ 0.006, 300 ≤ (Al + Mn) / (N + S) ≤ 1, 400, 0.6 ≤ Al / Si ≤ 4.0, the content is contained so that the Cu is 1.0 ≤ Cu / S ≤ 14.0 The slabs contained to satisfy the conditions are heated to a temperature of 1,100 ~ 1,250 ° C, followed by hot rolling, annealing hot rolled sheets or omitting hot rolled sheets, and cold rolling, followed by cold rolling cold rolled plates 750 ~ It is characterized in that the final annealing in the temperature range of 1,100 ℃.

In the method for manufacturing a non-oriented electrical steel sheet of the present invention, the slab is contained so that the Al, Si, Mn satisfies the condition of 1.7≤ (Al + Si + Mn / 2) ≤5.5, 1≤Al / Mn≤8 It features.

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 Al, Si, Mn alloy elements and N, S, Cu impurity elements 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 a graph showing the distribution density of a huge composite inclusion having an average size of 300 nm or more with (N + S) as the horizontal axis and the vertical axis as the basis of 0.02 / mm ² or more.

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, S, Cu content is appropriately adjusted, and Al / Si, Al / Mn, Al + Si + Mn / 2, Al + Mn, N + S, (Al By optimally managing the ratio of + Mn) / (N + S) and Cu / S, the hardness of the steel sheet can be lowered and the distribution density of the large composite inclusions having an average size of 300 nm or more in the steel sheet can be increased, thereby increasing the density of the non-oriented electrical steel sheet. The present invention has been completed by paying attention to the fact that the magnetic properties are significantly improved as well as the productivity and the punchability of the product are improved by the low hardness characteristics.

In the present invention, by weight%, Al: 1.0-3.0%, Si: 0.5-2.5%, Mn: 0.5-2.0%, Cu: 0.002-0.030%, N: 0.001-0.004%, S: 0.0005-0.004%, remainder And Al, Mn, N, S are 1.5 ≦ (Al + Mn) ≦ 3.5, 0.002 ≦ (N + S) ≦ 0.006, 300 ≦ (Al + Mn) / ( N + S) ≦ 1,400, 0.6 ≦ Al / Si ≦ 4.0, and the Cu is contained so as to satisfy the condition of 1.0 ≦ Cu / S ≦ 14.0.

As a result, the distribution density of nitrides and sulfides having an average size of 300 nm or more alone or a combination thereof is increased to 0.02 pieces / mm ² or more, so that the magnetism is excellent and the workability is improved by the low cross-sectional Vickers hardness (Hv1) of 190 or less. The highest quality non-oriented electrical steel sheet can be manufactured.

In addition, in the present invention, 0.3 to 0.5% of Al is first added in the steelmaking step so that deoxidation is performed, and then a residual alloy element is added, and after the addition of the remaining alloy element, the temperature of molten steel is maintained at 1,500 to 1,600 ° C. A slab having a composition of components is prepared, and the slab is heated to a temperature of 1,100 to 1,250 ° C., and then hot rolled, but hot finishing rolling is performed at 800 ° C. or higher, and the hot rolled hot rolled plate is hot rolled at a temperature range of 850 to 1,100 ° C. After annealing or omitting, pickling, cold rolling at a reduction ratio of 70 to 95%, and finally annealing the cold rolled cold rolled sheet 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: 1.0-3.0 wt%]

Al is added because it increases the resistivity of the material, lowers iron loss and forms nitride, and is contained 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 2.0%, it promotes the formation of [111] aggregates, which are disadvantageous to magnetism. Preferably limited to ˜2.0%.

[Cu: 0.002-0.030%]

The reason for limiting Cu to 0.002 ~ 0.03% is to raise it to 0.002% or more due to the addition of alloying elements such as Si, Al, and Mn when manufacturing steel sheet, and to remove it in the steelmaking process. This is because it is not preferable because the purity of various raw materials must be increased. In addition, since the Cu content is more than 0.03% to form fine inclusions to deteriorate the magnetic properties, the Cu content is preferably contained in 0.002 ~ 0.030%.

The reason for limiting Cu / S to 1 to 14 is that Cu and S are inferior in magnetism. If Cu / S is less than 1.0, fine CuS inclusions are formed and the magnetism deteriorates. When Cu / S exceeds 14.0, excess Cu, which is not bonded with S, is finely dispersed in the matrix to form clusters of several nm size, which hinders the movement of the magnetic wall and extremely deteriorates the magnetism.

[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%. If N exceeds 0.004%, coarsening of inclusions is not achieved and iron loss is increased. More preferable N content is 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 preferred S content is 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.

C is self-aging and should be limited to 0.004% or less. More preferred C content is 0.003% or less.

 Ti promotes the growth of [111] aggregates, which are undesirable crystal orientations in non-oriented electrical steel sheets, and therefore, Ti is preferably limited to 0.004% or less. More preferred Ti content is 0.002% or less.

In the present invention, (Al + Mn) is limited to 3.5% or less, because when 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 magnetism is thermally deteriorated. 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, (N + S) is limited to 0.002 ~ 0.006%, because the inclusions grow coarse 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 condition of 300≤ (Al + Mn) / (N + S) ≤1,400. 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 a graph showing (N + S) as the horizontal axis and (Al + Mn) as the vertical axis, based on whether or not the distribution density of a large composite inclusion having an average size of 300 nm or more is 0.02 / mm ² or more. .

2, (Al + Mn) is 3.5% or less, (N + S) is 0.002 ~ 0.006, while (Al + Mn) / (N + S) is 300 ~ 1,400 of the present invention In the range (inside the thick line), the inclusions are coarse and the distribution density of the giant composite inclusions having an average size of 300 nm or more is higher than 0.02 pieces / mm ² , while the magnetic properties are excellent. It can be seen that the distribution density of the large composite inclusions having a size of 300 nm or more is lower than 0.02 / 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.

In the present invention, Al / Si 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 the Al / Si is less than 0.6, the inclusions do not grow significantly, and the growth of the grains deteriorates and the magnetic heat is deteriorated, and the Si content is increased to increase the hardness. If Al / Si exceeds 4.0, the texture of the material becomes worse and the magnetic flux density becomes heat.

In the present invention, Al / Mn is preferably limited to 1 to 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 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 more than 32 (Ωm). However, if the resistivity exceeds 75 (Ωm), the content of the alloying element should be increased, so that the workability is poor, which makes it impossible to produce the conventional method. Therefore, the resistivity is appropriately managed to 32 ~ 75 (Ωm).

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% in order to satisfy the specific resistance of 32 ~ 75 (Ωm). Therefore, workability with low Vickers hardness (Hv1) of 190 or less is required. Excellent non-oriented electrical steel sheet can be obtained.

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 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, since the content of Si, Mn, Al alloy elements affecting the cold rolling is appropriately controlled and excellent in cold rolling, it is possible to apply a high rolling rate, so that 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. 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.

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.

Iron loss and magnetic flux density for each was measured and the presence or absence of a dispersed phase was shown in Table 6 below. In the formation of the fine inclusions, the inclusion of 50 nm or less inclusions and the known fine dispersion phase was expressed as "○", and the formation of no dispersion phase was denoted as "X".

Steel grade Al Si Mn Cu C S N Ti C1 2.0 1.0 1.0 0.020 0.002 0.0010 0.002 0.002 C2 2.0 1.0 1.0 0.015 0.002 0.0020 0.002 0.002 C3 2.0 1.0 1.0 0.015 0.002 0.0030 0.002 0.002 C4 2.0 1.0 1.0 0.010 0.002 0.0005 0.002 0.002 C5 2.0 1.0 1.0 0.004 0.002 0.0030 0.002 0.002 C6 2.0 1.0 1.0 0.004 0.002 0.0040 0.002 0.002 C7 1.5 2.0 1.0 0.020 0.002 0.0010 0.002 0.002 C8 1.5 2.0 1.0 0.015 0.002 0.0010 0.002 0.002 C9 1.5 2.0 1.0 0.015 0.002 0.0030 0.002 0.002 C10 1.5 2.0 1.0 0.010 0.002 0.0005 0.002 0.002 C11 1.5 2.0 1.0 0.004 0.002 0.0030 0.002 0.002 C12 1.5 2.0 1.0 0.004 0.002 0.0040 0.002 0.002

Steel grade Al / Si Al / Mn Al + Mn Cu / S Iron loss
(W15 / 50;
W / Kg) Magnetic flux density
(B50;
Tesla) Disperse phase Remarks C1 2.0 2.0 3.0 20.0 2.3 1.64 ○ Comparative Example C2 2.0 2.0 3.0 7.5 2.0 1.67 × Honor C3 2.0 2.0 3.0 5.0 2.0 1.66 × Honor C4 2.0 2.0 3.0 20.0 2.4 1.64 ○ Comparative Example C5 2.0 2.0 3.0 1.3 2.0 1.66 × Honor C6 2.0 2.0 3.0 1.0 1.9 1.66 × Honor C7 0.8 1.5 2.5 20.0 2.4 1.68 ○ Comparative Example C8 0.8 1.5 2.5 15.0 2.4 1.68 ○ Comparative Example C9 0.8 1.5 2.5 5.0 2.0 1.68 × Honor C10 0.8 1.5 2.5 20.0 2.3 1.64 ○ Comparative Example C11 0.8 1.5 2.5 1.3 2.0 1.67 × Honor C12 0.8 1.5 2.5 1.0 1.9 1.66 × Honor

From the results in Table 6, finely dispersed phases were not observed for steel grades C2, C3, C5, C6, C9, C11, and C12, in which Cu was controlled at 0.002 to 0.030% and Cu / S was controlled at 1.0 to 14.0. It can be seen that this is excellent.

On the other hand, in the steel grades C1, C4, C7, C8, and C10 with Cu / S greater than 14.0, there was a dispersed phase in which excess Cu, which could not bond with S, was finely dispersed at the base, and magnetic inferiority.

Claims (10)

By weight%, Al: 1.0-3.0%, Si: 0.5-2.5%, Mn: 0.5-2.0%, Cu: 0.002-0.030%, N: 0.001-0.004%, S: 0.0005-0.004%, C: 0.004% (Except 0%), Ti: 0.004% or less (except 0%), balance Fe and other unavoidable impurities, wherein Al, Mn, N, S, and Si are 1.5 ≦ (Al + Mn). ) ≤3.5, 0.002≤ (N + S) ≤0.006, 300≤ (Al + Mn) / (N + S) ≤1,400, 0.6≤Al / Si≤4.0, 1.7≤ (Al + Si + Mn / 2) ≤ 5.5, 1 ≤ Al / Mn ≤ 8 is contained so as to satisfy all the conditions, the Cu is a non-oriented electrical steel sheet having excellent magnetic properties contained to satisfy the conditions of 1.0 ≤ Cu / S ≤ 14.0. delete The method according to claim 1,
The non-oriented electrical steel sheet has excellent magnetic properties, characterized in that the cross-sectional Vickers hardness (Hv1) is 190 or less. delete The method according to claim 1 or 3,
Non-oriented electrical steel sheet having excellent magnetic properties, characterized in that the inclusions of nitrides and sulfides 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%, Cu: 0.002-0.030%, N: 0.001-0.004%, S: 0.0005-0.004%, C: 0.004% (Except 0%), Ti: 0.004% or less (except 0%), balance Fe and other unavoidable impurities, wherein Al, Mn, N, S, and Si are 1.5 ≦ (Al + Mn). ) ≤3.5, 0.002≤ (N + S) ≤0.006, 300≤ (Al + Mn) / (N + S) ≤1,400, 0.6≤Al / Si≤4.0, 1.7≤ (Al + Si + Mn / 2) ≤ 5.5, 1≤Al / Mn≤8 contained to satisfy all the conditions, the Cu is heated to a temperature of 1,100 ~ 1,250 ℃ containing the slab to satisfy the conditions of 1.0≤Cu / S≤14.0 and then hot rolled After annealing the hot rolled hot rolled sheet or omitting the hot rolled sheet annealing, cold rolling at a reduction ratio of 70 to 95%, and then finally annealing the cold rolled cold rolled sheet at a temperature range of 750 to 1,100 ° C. Method for producing non-oriented electrical steel sheet. delete delete The method of claim 6,
A method of manufacturing an excellent non-oriented electrical steel sheet, characterized in that the distribution density of the inclusion having an average size of 300nm or more is controlled to 0.02 pieces / mm ² or more. The method of claim 6,
Deodorization is performed by adding 0.3 ~ 0.5% of Al, and then the remaining alloying elements are added, and after the addition of the remaining alloying elements, the slab is manufactured by maintaining the temperature at 1,500 to 1,600 ° C. Method of manufacturing electrical steel sheet.

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