KR101329719B1 - Non-oriented electrical steel sheet with excellent magnetic property, and method for manufacturing the same - Google Patents

Abstract

The present invention relates to the production of non-oriented electrical steel sheet, Al: 0.7 to 2.7%, Si: 0.2 to 1.0%, Mn: 0.2 to 1.7%, Cu: 0.002 to 0.030%, N: 0.001 to 0.004% by weight , S: 0.0005 to 0.004%, balance Fe and other inevitable impurities, Al, Mn, N, S is (Al + Mn) ≤ 2.0, 0.002 ≤ (N + S) ≤ 0.006, 230 ≤ (Al + Mn) / (N + S) ≤ 1,000 is contained to satisfy all of the conditions, the Cu is non-oriented electrical steel sheet excellent magnetic properties contained to satisfy the conditions of 1.0 ≤ Cu / S ≤ 14.0 and a manufacturing method thereof To provide. 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 the non-oriented electrical steel sheet, it is necessary to extremely finely control impurities such as C, S, N, Ti, Cu, which form fine inclusions in the steel or inferior magnetism, thereby improving grain growth. 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 size of about 50 nm, and the fine inclusions thus produced not only increase the hysteresis loss by preventing grain growth during annealing. It reduces the permeability by blocking the movement of the magnetic wall during magnetization.

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.

Non-oriented electrical steel sheet of the present invention for solving the above problems by weight, Al: 0.7 ~ 2.7%, Si: 0.2 ~ 1.0%, Mn: 0.2 ~ 1.7%, Cu: 0.002 ~ 0.030%, N: 0.001 ~ 0.004%, S: 0.0005% to 0.004%, balance Fe and other unavoidable impurities, wherein Al, Mn, N, and S are (Al + Mn) ≦ 2.0, 0.002 ≦ (N + S) ≦ 0.006, 230? (Al + Mn) / (N + S) is contained so as to satisfy all the conditions of 1,000, the Cu is characterized in that it is contained so as to satisfy the conditions of 1.0 ≤ Cu / S ≤ 14.0.

The non-oriented electrical steel sheet of the present invention contains Al, Si, Mn to satisfy the conditions of 1.0≤ (Al + Si + Mn / 2) ≤2.0, 0.7≤Al / Si≤14.0, 1≤Al / Mn≤8 It is characterized by.

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: 0.7 ~ 2.7%, Si: 0.2 ~ 1.0%, Mn: 0.2 ~ 1.7%, Cu: 0.002 ~ 0.030%, N : 0.001% to 0.004%, S: 0.0005% to 0.004%, balance Fe and other unavoidable impurities, wherein Al, Mn, N, and S are (Al + Mn) ≦ 2.0, 0.002 ≦ (N + S) ≤ 0.006, 230 ≤ (Al + Mn) / (N + S)} ≤ 1,000 contained, and the Cu is contained in the slab to satisfy the conditions of 1.0 ≤ Cu / S ≤ 14.0 1,100 ℃ or more After hot rolling, the hot rolled hot rolled sheet is annealed or the hot rolled sheet is annealed and cold rolled at a reduction ratio of 70 to 95%, and the cold rolled cold rolled sheet is 750 to 1,100 ° C. Characterized in that the final annealing at.

In the method for manufacturing a non-oriented electrical steel sheet of the present invention, the slab is Al, Si, Mn is 1.0≤ (Al + Si + Mn / 2) ≤2.0, 0.7≤Al / Si≤14.0, 1≤Al / Mn≤8 It is characterized by containing so as to satisfy the conditions.

The 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 300 nm 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, the composition ratio of Al, Si, Mn, which are alloy elements, and N, S, Cu, which are impurity elements, is properly managed to increase the density of distribution of coarse inclusions, thereby increasing the growth of grains and improving the mobility of the magnetic walls. Excellent non-oriented electrical steel sheet can be produced. In addition, due to the low hardness, the customer's processability and productivity are excellent, and the cost of production 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.

The present inventors have investigated the effects of alloying elements, impurity elements, and relationships between elements on the formation of inclusions, and on the effects of magnetic properties and workability, respectively. As a result, Al, Si, Mn and , Appropriately control the content of the impurity elements N, S and Cu and Al / Si, Al / Mn, Al + Si + Mn / 2, Al + Mn, N + S, (Al + Mn) / (N + S) , By optimally managing the ratio of Cu / S, it is possible to increase the distribution density of the large composite inclusions with an average size of 300 nm or more in the steel sheet, thereby significantly improving the magnetic properties of the non-oriented electrical steel sheet, The present invention has been completed by paying attention to the fact that the productivity and punchability of the product are improved.

The present invention is in the weight%, Al: 0.7-2.7%, Si: 0.2-1.0%, Mn: 0.2-1.7%, Cu: 0.002-0.030%, N: 0.001-0.004%, S: 0.0005-0.004%, remainder It is composed of Fe and other unavoidable impurities, Al, Mn, N, S is (Al + Mn) ≤ 2.0, 0.002 ≤ (N + S) ≤ 0.006, 230 ≤ (Al + Mn) / (N + S) is contained so as to satisfy all the conditions of ≤ 1,000, and the Cu is characterized in that it is contained so as to satisfy the conditions of 1.0 ≤ Cu / S ≤ 14.0.

Accordingly, the distribution density of nitrides and sulfides having an average size of 300 nm or more alone or incorporating them is increased to 0.02 / mm 2 or more, and thus, high-quality non-oriented electrical steel sheets having excellent magnetic properties 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 compositional composition is prepared, 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 more, and the hot rolled hot rolled sheet is annealed at a temperature range of 850 ° C. or more. Omitting this, pickling, cold rolling at a reduction ratio of 70 to 95%, and final annealing of the cold rolled cold rolled steel at a temperature range of 750 to 1,100 ° C. produce non-oriented electrical steel sheets having excellent magnetic properties and workability. It features.

In the case of Al, Si, and Mn, which are alloying elements of steel, the alloying elements are elements added to lower iron loss of electrical steel sheet, but as the added content thereof increases, the magnetic flux density decreases and the workability of the material is deteriorated. These alloying components should be properly set 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, it is necessary to increase the frequency of formation of the inclusions so as to minimize deterioration of the magnetic properties.

The inventors first discovered that when Al, Mn, N, S, and Cu were added or controlled to satisfy specific conditions, a huge composite inclusion composed of nitrides or sulfides was formed. By adjusting the distribution density of such composite inclusions, In view of the fact that the magnetism is greatly improved despite containing a minimum amount of alloying elements deteriorating workability, the present invention has been proposed.

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

[Al: 0.7-2.7 wt%]

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

[Si: 0.2-1.0 wt%]

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

[Mn: 0.2-1.7 wt%]

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

[Cu: 0.002-0.030 wt%]

Cu combines with S to form inclusions or exists as Cu alone to form a fine dispersed phase, so the ratio must be well controlled with S. In order to control the Cu content to less than 0.002%, it is not preferable to increase the purity of various raw materials such as alloying elements, and when the Cu content exceeds 0.030%, Cu inclusions or dispersed phases are inferior to magnetism, so Cu is 0.002 ~ 0.030 It is contained in%.

Cu / S is preferably managed at 1.0 to 14.0, because when Cu / S is less than 1.0, fine CuS inclusions are formed to deteriorate magnetism, and when Cu / S exceeds 14.0, excess Cu that is not bonded with S This is because it disperses finely at the base and inferiors 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 above impurity elements, impurities such as C and Ti may be inevitably mixed.

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 2.0% or less, because when the total amount of Al and Mn exceeds 2.0%, the fraction of the [111] aggregate tissue, which is disadvantageous to magnetism, increases and the magnetism is thermally deteriorated. When the total amount of Al and Mn is less than 0.9%, nitrides, sulfides, or two complex inclusions are not coarse to form magnetic heat. However, in the present invention, Al is contained in an amount of 0.7% or more and Mn is 0.2% or more. Since the total amount of Al and Mn is 0.9% or more, magnetic deterioration is prevented.

In the present invention, the total amount of N and S (N + S) is limited to 0.002 ~ 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 230 ≦ (Al + Mn) / (N + S) ≦ 1,000. Within this range, magnetism is improved by coarse inclusions, which increases the density of distribution of large composite inclusions. Outside this range, coagulation of inclusions does not become coarse, and the formation frequency of huge composite inclusions is low. 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. .

Referring to the illustration of FIG. 2, (Al + Mn) is 2.0% or less, (N + S) is 0.002 to 0.006, and (Al + Mn) / (N + S) is 230 to 1,000. In the range (inside the thick line), the inclusions are coarse and the distribution density of the huge 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, while the coarse inclusions are not formed in the range outside the present invention and have an average size. It can be seen that the distribution density of the large composite inclusions of 300 nm or more is lower than 0.02 / mm ^{2, and the} inferior texture is degraded due to the 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 determined by measuring the longest length and the shortest length of the inclusions observed in the cross section of the steel sheet and averaging them.

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

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 alloy component related to a specific resistance is demonstrated. Recently, the demand for high magnetic flux density products to achieve high efficiency in the motor is rapidly increasing, and accordingly, the demand for non-oriented electrical steel sheet to improve the magnetic flux density by lowering the specific resistance is increasing. Therefore, the specific resistance (intrinsic resistance) is lowered to 36 (Ωm) or less to increase the magnetic flux density, and it is appropriate to manage the specific resistance to 25 (Ωm) or more to cope with high-speed rotation.

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

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

According to this empirical formula, (Al + Si + Mn / 2) should be managed at 1.0 ~ 2.0% in order to satisfy the specific resistance 25 ~ 36 (Ωm). Therefore, workability with low Vickers hardness (Hv1) of 140 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.

The hot rolled hot rolled sheet is annealed at a temperature of 850 ° C. or higher. If the hot-rolled sheet annealing temperature is less than 850 ° C., the tissue does not grow or grows finely, so that the synergy effect of the magnetic flux density decreases. If the hot rolled sheet annealing temperature is too high, the magnetic properties are rather deteriorated, and the rolling workability may deteriorate due to the deformation of the plate shape. Therefore, the hot rolled sheet annealing temperature is preferably performed at a temperature of 1,100 ° C. or lower. 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 as described above, 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, 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. 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. Impurities C, S, N, and Ti of the material were all controlled to 0.002%, 0.3 to 0.5% of Al was added to the molten steel to promote the formation of inclusions, and the remaining Al, Si, and Mn 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 plate thickness of 2.3 mm. The hot rolled hot rolled sheet was annealed at 1,050 ° C. for 4 minutes and then pickled. After cold rolling, the sheet thickness was 0.50 mm and final annealing was performed at 900 ° C. for 30 seconds.

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

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

Steel grade Al /
Si Al /
Mn Al +
Mn N + S (Al + Mn)
/ (N + S) Al + Si
+ Mn / 2 Inclusion
size
(Nm) Inclusion
Distribution density
(1 / mm ² ) Iron loss
(W15 / 50; W / Kg) Magnetic flux density
(B50;
Tesla) Hardness
(Hv1) Remarks A1 7.5 7.5 1.7 0.0040 425 1.8 450 0.40 3.2 1.73 140 Honor A2 7.5 3.0 2.0 0.0040 500 2.0 500 0.35 3.0 1.73 140 Honor A3 3.5 1.4 1.2 0.0040 300 1.2 300 0.30 4.0 1.74 110 Honor A4 5.4 9.0 3.0 0.0040 750 3.4 250 0.01 3.0 1.68 157 Comparative Example A5 3.4 5.7 2.0 0.0040 500 2.4 250 0.01 2.9 1.69 145 Comparative Example A6 1.4 2.3 1.0 0.0040 250 1.4 450 0.05 3.5 1.74 115 Honor A7 1.0 1.0 1.0 0.0040 250 1.3 50 0.01 4.5 1.74 110 Comparative Example A8 1.0 1.0 1.0 0.0040 250 1.3 75 0.01 4.5 1.74 110 Comparative Example A9 4.4 11.0 2.4 0.0040 600 2.8 400 0.01 2.8 1.68 150 Comparative Example A10 2.4 6.0 1.4 0.0040 350 1.8 600 0.15 3.2 1.73 130 Honor A11 10 5.0 1.2 0.0040 300 1.2 250 0.01 4.5 1.74 105 Comparative Example A12 6.0 6.0 1.4 0.0040 350 1.5 400 0.20 3.5 1.74 105 Honor A13 5.0 5.0 1.2 0.0040 300 1.3 300 0.18 3.6 1.74 110 Honor A14 3.1 11.0 2.4 0.0040 600 3.0 400 0.01 2.8 1.69 160 Comparative Example A15 1.0 3.5 0.9 0.0040 225 1.5 150 0.01 3.9 1.74 130 Comparative Example A16 6.5 1.9 2.0 0.0040 500 1.9 350 0.25 2.9 1.72 130 Honor A17 7.5 1.5 2.5 0.0040 625 2.2 250 0.01 2.8 1.69 140 Comparative Example A18 6.0 1.2 2.2 0.0040 550 1.9 250 0.01 2.9 1.70 130 Comparative Example A19 1.8 0.9 1.9 0.0040 475 1.9 200 0.01 3.2 1.70 135 Comparative Example A20 1.3 1.1 1.7 0.0040 425 2.0 350 0.05 3.5 1.73 140 Honor A21 2.0 1.3 1.8 0.0040 450 1.9 400 0.05 3.3 1.73 140 Honor

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

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

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

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

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

Steel grade Al /
Si Al /
Mn Al +
Mn N + S (Al + Mn)
/ (N + S) Al + Si
+ Mn / 2 Inclusion
size
(Nm) Inclusion
Distribution density
(1 / mm ² ) Iron loss
(W15 / 50;
W / Kg) Magnetic flux density
(B50;
Tesla) Hardness
(Hv1) Remarks B1 2.0 3.3 1.3 0.0020 650 1.7 350 0.150 3.2 1.73 135 Honor B2 2.3 3.5 0.9 0.0060 150 1.1 200 0.010 4.2 1.71 130 Comparative Example B3 2.3 1.4 1.2 0.0050 240 1.3 300 0.200 3.5 1.74 130 Honor B4 1.4 2.3 1.0 0.0035 286 1.4 450 0.050 3.4 1.73 130 Honor B5 3.3 1.4 1.7 0.0010 1700 1.7 50 0.010 3.5 1.69 140 Comparative Example B6 3.3 1.4 1.7 0.0060 283 1.7 350 0.200 3.2 1.74 140 Honor B7 2.4 1.2 2.2 0.0040 550 2.2 250 0.010 2.9 1.68 140 Comparative Example B8 6.0 4.0 1.5 0.0025 600 1.6 450 0.070 3.3 1.74 140 Honor B9 1.8 1.1 1.7 0.0040 425 1.8 550 0.080 3.1 1.73 135 Honor B10 1.8 1.1 1.7 0.0070 243 1.8 250 0.010 3.5 1.69 135 Comparative Example B11 1.8 1.8 1.4 0.0060 233 1.7 500 0.150 3.2 1.73 135 Honor B12 1.8 1.8 1.4 0.0045 311 1.7 600 0.180 3.2 1.74 135 Honor B13 1.8 1.8 1.4 0.0010 1400 1.7 50 0.018 3.7 1.72 135 Comparative Example

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

On the other hand, steel grades B2, B5, and B13 (Al + Mn) / (N + S) was not observed the inclusions having a size of more than 300nm outside the scope of the present invention, iron loss and magnetic flux density was inferior. In the case of B10, N + S is out of the scope of the present invention, and steel grade B7 has no observed inclusions having a size of 300 nm or more out of the range of Al + Mn, and inferior in iron loss and magnetic flux density.

Vacuum dissolution in the lab produced a steel ingot as shown in Table 5 below. 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 1.5 0.2 0.5 0.020 0.003 0.0010 0.002 0.0025 C2 1.5 0.2 0.5 0.015 0.003 0.0020 0.002 0.0025 C3 1.5 0.2 0.5 0.015 0.003 0.0030 0.002 0.0025 C4 1.5 0.2 0.5 0.010 0.003 0.0005 0.002 0.0025 C5 1.5 0.2 0.5 0.004 0.003 0.0030 0.003 0.0025 C6 1.5 0.2 0.5 0.004 0.003 0.0040 0.004 0.0025 C7 0.9 0.7 0.8 0.020 0.003 0.0010 0.002 0.0025 C8 0.9 0.7 0.8 0.015 0.003 0.0010 0.004 0.0025 C9 0.9 0.7 0.8 0.015 0.003 0.0030 0.002 0.0025 C10 0.9 0.7 0.8 0.010 0.003 0.0005 0.002 0.0025 C11 0.9 0.7 0.8 0.004 0.003 0.0030 0.002 0.0025 C12 0.9 0.7 0.8 0.004 0.003 0.0040 0.003 0.0025

Steel grade Al / Si Al / Mn Cu / S Iron loss
(W15 / 50;
W / Kg) Magnetic flux density
(B50;
Tesla) Disperse phase Remarks C1 7.5 3.0 20.0 3.4 1.72 ○ Comparative Example C2 7.5 3.0 7.5 2.7 1.74 × Honor C3 7.5 3.0 5.0 2.7 1.75 × Honor C4 7.5 3.0 20.0 3.5 1.71 ○ Comparative Example C5 7.5 3.0 1.3 2.8 1.74 × Honor C6 7.5 3.0 1.0 2.9 1.74 × Honor C7 1.3 1.1 20.0 3.7 1.71 ○ Comparative Example C8 1.3 1.1 15.0 3.5 1.72 ○ Comparative Example C9 1.3 1.1 5.0 3.1 1.74 × Honor C10 1.3 1.1 20.0 3.3 1.73 ○ Comparative Example C11 1.3 1.1 1.3 3.5 1.72 × Honor C12 1.3 1.1 1.0 2.9 1.74 × Honor

From the results in Table 6, steel grades C2, C3, C5, C6, C9, C11, and C12, in which Cu is controlled at 0.002 to 0.030% and Cu / S is controlled at 1.0 to 14.0, have no fine dispersed phase, and are magnetic. 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: 0.7-2.7%, Si: 0.2-1.0%, Mn: 0.2-1.7%, 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, Si, Mn, N, and S are (Al + Mn) ≦ 2.0, 0.002≤ (N + S) ≤0.006, 230≤ (Al + Mn) / (N + S) ≤1,000, 1.0≤ (Al + Si + Mn / 2) ≤2.0, 0.7≤Al / Si≤14.0, A non-oriented electrical steel sheet having excellent magnetic properties, which is contained so as to satisfy all the conditions of 1 ≦ Al / Mn ≦ 8, and the Cu is satisfied so as 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 less than 140. 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: 0.7-2.7%, Si: 0.2-1.0%, Mn: 0.2-1.7%, 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, Si, Mn, N, and S are (Al + Mn) ≦ 2.0, 0.002≤ (N + S) ≤0.006, 230≤ (Al + Mn) / (N + S)} ≤1,000, 1.0≤ (Al + Si + Mn / 2) ≤2.0, 0.7≤Al / Si≤14.0 , 1≤Al / Mn≤8 is contained to satisfy all the conditions, the Cu is heated to a temperature of 1,100 ~ 1,250 ℃ containing the slab to satisfy the condition 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 70-95%, and then finally annealing the cold rolled cold rolled sheet in the temperature range of 750 ~ 1,100 ℃ Method for producing 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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