Non-oriented electrical steel sheet and method for producing same

Abstract

The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same, and more particularly, to a non-oriented electrical steel sheet which can be preferably used as an iron core or the like of a motor, and a method for manufacturing the same. The purpose of one aspect of the present invention is to provide: a non-oriented electrical steel sheet having excellent magnetism; and a method for producing the non-oriented electrical steel sheet.

Description

Technical Field

[0001] The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same, and more particularly, to a non-oriented electrical steel sheet that can be preferably used for cores of electric motors and the like and a method for manufacturing the same. Background Art

[0002] In recent years, as disasters caused by climate change have increased, countries around the world have announced carbon neutral roadmaps for 2050. The total carbon emissions reached 3.9 billion tons in 2020, of which the emissions from internal combustion engines reached 940 million tons, accounting for 24%. Therefore, there is a great demand for carbon neutrality in this field through the electrification of internal combustion engines. For this reason, in the field of mobile tools, electrification is rapidly proceeding, led by electric vehicles. The characteristics required for driving motors in new mobile tools are to extend the driving distance and increase the maximum speed. This is directly related to the low iron loss characteristics of electrical steel sheets. When the iron loss of electrical steel sheets is low, the efficiency is more excellent, so the driving distance can be extended. Therefore, the low iron loss characteristics of electrical steel sheets are crucial. For this reason, Si, Al, and Mn are usually added in large amounts to electrical steel sheets to ensure low iron loss at high frequencies.

[0003] However, due to impurities present in the steel, precipitates such as nitrides and carbides are formed, which hinder grain growth and magnetic domain movement, resulting in poor iron loss. Therefore, it is necessary to control the precipitates that hinder grain growth and magnetic domain movement to improve the magnetic properties. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] An object of one aspect of the present invention is to provide a non-oriented electrical steel sheet having excellent magnetic properties and a method for manufacturing the same.

[0006] (II) Technical Solutions

[0007] An embodiment of the present invention provides a non-oriented electrical steel sheet. In terms of weight %, the non-oriented electrical steel sheet contains: Si: 3.3 - 4.3%, Al: 0.8 - 1.7%, Mn: 0.3 - 2.5%, Cr: 0.01 - 0.05%, S: 0.005% or less (except 0%), P: 0.01% or less (except 0%), N: 0.001 - 0.004%, Ti: 0.001 - 0.005%, the balance being Fe and other inevitable impurities, and the non-oriented electrical steel sheet satisfies the following relational expression 1, and the total number density of nitrides and carbides having a diameter of 1 - 3 μm is 50 per mm 2 or less.

[0008] [Relational Expression 1] 0.02 ≤ Al × Ti / Cr ≤ 0.8

[0009] The non-oriented electrical steel sheet may further contain one or more of C: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

[0010] The non-oriented electrical steel sheet may further contain one or more of Sn: 0.1% or less, Sb: 0.1% or less, Ni: 0.05% or less, Cu: 0.005 - 0.2%, and Zn: 0.01% or less.

[0011] The non-oriented electrical steel sheet may further contain one or more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005% or less, and Mg: 0.005% or less.

[0012] The non-oriented electrical steel sheet may further contain one or more of Bi, Pb, Ge, and As, and the contents of Bi, Pb, Ge, and As are 0.20% or less (except 0%) respectively or the total amount is 0.20% or less (except 0%).

[0013] The coercive force of the non-oriented electrical steel sheet may be 40 A / m or less even after magnetization to 2000 A / m.

[0014] Another embodiment of the present invention provides a method for manufacturing a non-oriented electrical steel sheet, characterized in that the manufacturing method includes the following steps: heating a slab at 1100 - 1250 °C, and by weight, the slab contains: Si: 3.3 - 4.3%, Al: 0.8 - 1.7%, Mn: 0.3 - 2.5%, Cr: 0.01 - 0.05%, S: 0.005% or less (except 0%), P: 0.01% or less (except 0%), N: 0.001 - 0.004%, Ti: 0.001 - 0.005%, the balance being Fe and other inevitable impurities, and satisfying the following relational expression 1; hot-rolling the heated slab at 800 - 1000 °C to obtain a hot-rolled sheet; cold-rolling the hot-rolled sheet with a reduction ratio of 70 - 95% to obtain a cold-rolled sheet; and finally annealing the cold-rolled sheet, wherein the final annealing includes a heating process and a soaking process, the highest heating temperature is 50 °C or more higher than the soaking temperature, and the soaking time is 30 seconds or more longer than the heating time.

[0015] [Relational expression 1] 0.02 ≤ Al × Ti / Cr ≤ 0.8

[0016] The slab may further contain one or more of C: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

[0017] The slab may further contain one or more of Sn: 0.1% or less, Sb: 0.1% or less, Ni: 0.05% or less, Cu: 0.005 - 0.2%, and Zn: 0.01% or less.

[0018] The slab may further contain one or more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005% or less, and Mg: 0.005% or less.

[0019] The slab may further contain one or more of Bi, Pb, Ge, and As, and the contents of Bi, Pb, Ge, and As are each 0.20% or less (except 0%) or the total amount is 0.20% or less (except 0%).

[0020] After the step of obtaining the hot-rolled sheet, it may further include a step of annealing the hot-rolled sheet at 850 - 1150 °C.

[0021] The cold rolling may be performed 1 or 2 times.

[0022] (III) Advantageous Effects

[0023] According to one aspect of the present invention, a non-oriented electrical steel sheet having excellent magnetic properties and a method for manufacturing the same can be provided. Best Mode

[0024] In order to improve the iron loss of the non-oriented electrical steel sheet, it is necessary to add a large amount of Si, Al, and Mn as elements that increase the resistivity, but it is also necessary to actively control the precipitates that hinder grain growth and magnetic domain movement. In particular, precipitates such as nitrides and carbides precipitate in a fine size at grain boundaries and the like, thereby reducing the iron loss. Therefore, the present inventors recognized that by optimizing the alloy composition that affects the formation of precipitates, controlling the temperature and time in the heating zone and soaking zone in the final annealing process in particular among the manufacturing conditions, and controlling the precipitates, a non-oriented electrical steel sheet with excellent magnetic properties can be manufactured, and thus the present invention was completed.

[0025] Hereinafter, a non-oriented electrical steel sheet according to an embodiment of the present invention will be described. First, the alloy composition will be described. Unless otherwise specified, the contents of the alloy compositions described below represent weight %.

[0026] Si: 3.3 - 4.3%

[0027] Si is an element that plays a role in reducing iron loss by increasing the resistivity of the material. When the content of the Si is less than 3.3%, the effect of improving high-frequency iron loss is minimal. When the content of the Si exceeds 4.3%, due to the increase in hardness, productivity and stamping performance may deteriorate. Therefore, the content of the Si preferably has a range of 3.3 - 4.3%. The lower limit of the content of the Si is more preferably 3.35%, and further preferably 3.40%. The upper limit of the Si content is more preferably 4.25%, and further preferably 4.20%.

[0028] Al: 0.8 - 1.7%

[0029] Al is an element that plays a role in increasing the resistivity of the material and reducing iron loss. When the content of the Al is less than 0.8%, there is no effect of reducing high-frequency iron loss, and fine nitrides are formed, resulting in poor magnetic properties. When the content of the Al exceeds 1.7%, problems with changes in the physical properties of the mold powder occur during the continuous casting process, thus significantly reducing productivity. Therefore, the content of the Al preferably has a range of 0.8 - 1.7%. The lower limit of the Al content is more preferably 0.85%, and further preferably 0.90%. The upper limit of the Al content is more preferably 1.65%, and further preferably 1.60%.

[0030] Mn: 0.3 - 2.5%

[0031] Mn is an element that plays a role in improving iron loss by increasing the resistivity of the material and forming sulfides. When the content of the Mn is less than 0.3%, MnS precipitates finely, resulting in poor magnetic properties. When the content of the Mn exceeds 2.5%, it promotes the formation of a {111} texture that is unfavorable for magnetism, resulting in a sharp decrease in magnetic flux density. Therefore, the content of the Mn preferably has a range of 0.3 - 2.5%. The lower limit of the content of the Mn is more preferably 0.35%, further preferably 0.40%, and most preferably 0.45%. The upper limit of the content of the Mn is more preferably 2.45%, further preferably 2.40%, and most preferably 2.35%.

[0032] Cr: 0.01 - 0.05%

[0033] Cr does not directly form precipitates and may cause segregation, but when experiencing various temperature changes during the manufacturing process, Cr forms solid solutions with Al and Ti, etc., but also forms intermetallic compounds, and also hinders the movement of magnetic domains like precipitates, thus deteriorating the magnetic properties. When the content of the Cr is less than 0.01%, it is difficult to fully obtain the segregation effect. When the content of the Cr exceeds 0.05%, a large amount of intermetallic compounds are formed, resulting in poor magnetic properties.

[0034] S: 0.005% or less (except 0%)

[0035] S reacts with Mn, Cu, etc. to form sulfides, resulting in poor magnetism. Therefore, the content of S must be controlled below 0.005%.

[0036] P: Below 0.01% (except 0%)

[0037] P hinders grain boundary bonding and enhances brittleness, thus deteriorating the rolling productivity. In particular, in the steel containing 3.2% or more of Si, the content of P must be controlled below 0.01%.

[0038] N: 0.001 - 0.004%

[0039] N reacts with Al, Ti, etc. to form fine nitrides. Since N present in the atmosphere dissolves in the steel, in order to control the content of N below 0.001%, the process cost increases excessively. When the content of N exceeds 0.004%, due to the formation of excessive nitrides, the grain growth property deteriorates, thus the magnetism deteriorates. The lower limit of the content of N is more preferably 0.0012%, further preferably 0.0014%, and most preferably 0.0016%. The upper limit of the content of N is more preferably 0.0035%, further preferably 0.0030%, and most preferably 0.0025%.

[0040] Ti: 0.001 - 0.005%

[0041] Ti forms various fine precipitates such as nitrides and carbides. In order to control the content of Ti below 0.001%, the process cost increases excessively. When the content of Ti exceeds 0.005%, a large amount of precipitates are formed, making it difficult to obtain an appropriate grain size.

[0042] The remaining component is iron (Fe). However, in the normal manufacturing process, unwanted impurities inevitably mix in from raw materials or the surrounding environment, so these impurities cannot be completely excluded. These impurities are well-known to those skilled in the normal manufacturing process, so all of their contents are not particularly mentioned in this specification.

[0043] The non-oriented electrical steel sheet of the present invention may further contain one or more of C: below 0.005%, Nb: below 0.005%, and V: below 0.005%.

[0044] C: Below 0.005%

[0045] C reacts with N, Ti, Nb, V, etc. to form fine carbides, which play a role in hindering grain growth and magnetic domain movement, and the upper limit of the C content is limited to 0.005%. More specifically, the C content can be 0.0001 - 0.005%. More specifically, the C content can be 0.0005 - 0.003%.

[0046] Nb: 0.005% or less

[0047] Nb plays a role in combining with C, N, etc. to form fine nitrides and hindering magnetic domain movement. Therefore, the upper limit of Nb is limited to 0.005%. More specifically, the Nb content can be 0.0001 - 0.005%. More specifically, the Nb content can be 0.0005 - 0.003%.

[0048] V: 0.005% or less

[0049] V plays a role in combining with C, N, etc. to form fine nitrides and hindering magnetic domain movement. Therefore, the upper limit of V is limited to 0.005%. More specifically, the V content can be 0.0001 - 0.005%. More specifically, the V content can be 0.0005 - 0.003%.

[0050] The non-oriented electrical steel sheet of the present invention may further contain one or more of Sn: 0.1% or less, Sb: 0.1% or less, Ni: 0.05% or less, Cu: 0.005 - 0.2%, and Zn: 0.01% or less.

[0051] Sn: 0.1% or less

[0052] Sn is an element that segregates at grain boundaries. The purpose of adding Sn is to inhibit the diffusion of nitrogen through grain boundaries, inhibit the {111} texture (which is harmful to magnetism), increase the favorable {100} texture, and improve magnetic properties. When the Sb content exceeds 0.1%, it hinders grain growth, reduces magnetism, and deteriorates rollability. More specifically, the Sn content can be 0.001 - 0.1%. More specifically, the Sn content can be 0.005 - 0.08%.

[0053] Sb: 0.1% or less

[0054] Sb is an element that segregates at grain boundaries. The purpose of adding Sn is to inhibit the diffusion of nitrogen through grain boundaries, inhibit the {111} texture (which is harmful to magnetism), increase the favorable {100} texture, and improve magnetic properties. When the Sb content exceeds 0.1%, it hinders grain growth, reduces magnetism, and deteriorates rollability. More specifically, the Sb content can be 0.001 - 0.1%. More specifically, the Sb content can be 0.005 - 0.08%.

[0055] Ni: 0.05% or less

[0056] Ni reacts with impurity elements to form fine sulfides, carbides and nitrides, which have an adverse effect on magnetism. Therefore, the upper limit of Ni is limited to 0.05%. More specifically, the content of Ni can be 0.0001 - 0.050%. More specifically, the content of Ni can be 0.001 - 0.030%.

[0057] Cu: 0.005 - 0.2%

[0058] Cu plays a role in forming sulfides together with Mn. When the content of Cu is less than 0.005%, fine (Cu·Mn)S precipitates and the magnetism may deteriorate. When the content of Cu exceeds 0.2%, high-temperature brittleness occurs and cracks may form during continuous casting or hot rolling. More specifically, the content of Cu can be 0.010 - 0.1%.

[0059] Zn: 0.01% or less

[0060] Zn, as an impurity, reduces magnetism. Therefore, the upper limit of the Zn is limited to 0.01%. More specifically, the content of Zn can be 0.0001 - 0.01%. More specifically, the content of Zn can be 0.001 - 0.008%.

[0061] The non-oriented electrical steel sheet of the present invention may further contain one or more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005% or less, and Mg: 0.005% or less.

[0062] They react with inevitably contained C, S, N, etc. to form fine carbides, nitrides or sulfides, which may have an adverse effect on magnetism. Therefore, the upper limit can be defined as above.

[0063] The non-oriented electrical steel sheet of the present invention may further contain one or more of Bi, Pb, Ge, and As, and the contents of Bi, Pb, Ge, and As are 0.20% or less (except 0%) respectively, or the total amount is 0.20% or less (except 0%).

[0064] When the above elements are further added, they segregate at grain boundaries, relieve stress concentration at grain boundaries during cold rolling, and inhibit the recrystallization of <111> / ND-oriented grains during the subsequent recrystallization annealing, thereby increasing the magnetic flux density. If these elements are added appropriately, the above effects can be further obtained. However, when an excessive amount of these elements is contained, a large amount of segregation occurs, grain growth is inhibited, and the magnetic flux density and iron loss may deteriorate instead. More specifically, one or more of Bi, Pb, Ge, and As may be included, and the contents of Bi, Pb, Ge, and As may be 0.0001 - 0.20% respectively or the total amount may be 0.0001 - 0.20%. More specifically, one or more of Bi, Pb, Ge, and As may be included, and the contents of Bi, Pb, Ge, and As may be 0.001 - 0.10% respectively or the total amount may be 0.001 - 0.10%.

[0065] The non-oriented cold-rolled steel sheet of the present invention preferably satisfies the following relational expression 1 while satisfying the above alloy composition.

[0066] [Relational expression 1] 0.02 ≤ Al × Ti / Cr ≤ 0.8

[0067] Al, Cr, and Ti form precipitates according to the heat treatment conditions and also form solid solutions. Therefore, if the heat treatment conditions are appropriately adjusted, the size and fraction of the precipitates can be controlled. When the value of Al × Ti / Cr is less than 0.02, Cr is excessive, and the magnetic properties deteriorate due to the formation of Cr-based intermetallic compounds. When the value of Al × Ti / Cr exceeds 0.8, Al or Ti is excessive, and the precipitates cannot be controlled. The lower limit of the Al × Ti / Cr value is more preferably 0.025, further preferably 0.03, and most preferably 0.035. The upper limit of the Al × Ti / Cr value is more preferably 0.75, further preferably 0.7.

[0068] In the non-oriented cold-rolled steel sheet of the present invention, the total number density of nitrides and carbides having a diameter of 1 - 3 μm is preferably 30 / mm 2 or less. Fine nitrides and carbides having a diameter of 1 - 3 μm hinder grain growth and magnetic domain movement, thereby deteriorating the magnetic properties. Therefore, it is necessary to minimize such fine nitrides and carbides. When the total number density of the nitrides and carbides having a diameter of 1 - 3 μm is controlled at 50 / mm 2 or less, the grain growth property is improved, and magnetic domain movement becomes easier during magnetization. The nitrides and carbides can be observed by SEM. Nitrides refer to precipitates containing 5 wt% or more of N, and carbides can be defined as precipitates containing 5 wt% or more of C.

[0069] The non-oriented electrical steel sheet of the present invention provided as described above can have a coercive force of 40 A / m or less even after magnetization to 2000 A / m. In the present invention, the lower the coercive force, the more advantageous, and thus the lower limit thereof is not particularly limited. However, the lower limit of the coercive force can be, for example, 20 A / m.

[0070] In order to reduce eddy current loss in a high-frequency rotating electric machine, the larger the resistivity, the more excellent, but when the resistivity is too large, the magnetic flux density may deteriorate. The non-oriented electrical steel sheet of the present invention can have a resistivity of 55 - 85 μΩcm. In addition, the resistivity can be inferred from 13.25 + 11.3×(Si + Al + Mn / 2).

[0071] Hereinafter, a method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention will be described.

[0072] First, a slab satisfying the above alloy composition and relational expression 1 is heated at 1100 - 1250°C. When the heating temperature of the slab is lower than 1100°C, the rolling temperature is too low, and there is a disadvantage that it cannot be rolled to a desired thickness. When the heating temperature of the slab exceeds 1250°C, inclusions are finely precipitated during the rolling process, resulting in a disadvantage of deteriorating the magnetic properties. Therefore, the heating temperature of the slab preferably has a range of 1100 - 1250°C. The lower limit of the heating temperature of the slab is more preferably 1110°C, further preferably 1120°C, and most preferably 1130°C. The upper limit of the heating temperature of the slab is more preferably 1230°C, further preferably 1210°C, and most preferably 1190°C.

[0073] After that, the heated slab is hot finish-rolled at 800 - 1000°C to obtain a hot-rolled sheet. When the hot finish-rolling temperature is lower than 800°C, there is a disadvantage of too high rolling load. When the hot finish-rolling temperature exceeds 1000°C, there is a disadvantage of difficult shape control. The lower limit of the hot finish-rolling temperature is more preferably 820°C, further preferably 840°C, and most preferably 850°C. The upper limit of the hot finish-rolling temperature is more preferably 980°C, further preferably 960°C, and most preferably 950°C.

[0074] After the step of obtaining the hot-rolled sheet, the hot-rolled sheet can also be annealed at 850 - 1150 °C. Through the hot-rolled sheet annealing process, the crystal orientation beneficial to magnetism can be increased. When the annealing temperature of the hot-rolled sheet is lower than 850 °C, the grains may not grow or grow microscopically, so the effect of increasing the magnetic flux density may be small. When the annealing temperature of the hot-rolled sheet exceeds 1150 °C, the magnetic properties may deteriorate instead, and due to the deformation of the sheet shape, the rolling processability may deteriorate. Therefore, the annealing temperature of the hot-rolled sheet can have a range of 850 - 1150 °C. The lower limit of the annealing temperature of the hot-rolled sheet is more preferably 870 °C, further preferably 890 °C, and most preferably 910 °C. The upper limit of the annealing temperature of the hot-rolled sheet is more preferably 1140 °C, further preferably 1130 °C, and most preferably 1120 °C. In addition, the annealing of the hot-rolled sheet can be omitted.

[0075] After that, the hot-rolled sheet is cold-rolled with a reduction ratio of 70 - 95% to obtain a cold-rolled sheet. When the cold reduction ratio is less than 70%, the deformed structure is uneven, and there is a disadvantage that the magnetic deviation of the final product becomes large. When the cold reduction ratio exceeds 95%, the texture development unfavorable to magnetism occurs, and there is a disadvantage that the magnetism of the final product may deteriorate. Therefore, the cold reduction ratio preferably has a range of 70 - 95%. The lower limit of the cold reduction ratio is more preferably 72%, further preferably 74%, and most preferably 76%. The upper limit of the cold reduction ratio is more preferably 93%, further preferably 91%, and most preferably 89%. In order to obtain the desired thickness, the cold rolling can be carried out 1 or 2 times.

[0076] Thereafter, preferably, the cold-rolled sheet is subjected to final annealing. The final annealing includes processes of heating and soaking, where the maximum heating temperature is more than 50°C higher than the soaking temperature, and the soaking time is more than 30 seconds longer than the heating time. The reason for controlling the heating temperature to be relatively high is to re-dissolve fine precipitates such as nitrides and carbides. The reason for controlling the soaking temperature at a low level is to inhibit grain growth to improve high-frequency iron loss. The reason for making the soaking time longer than the heating time is to minimize magnetic deviation by reducing the non-uniformity of particle size. When the difference between the maximum heating temperature and the soaking temperature is less than 50°C or the difference between the soaking time and the heating time is less than 30 seconds, it is difficult to obtain the above-mentioned effects sufficiently. The difference between the maximum heating temperature and the soaking temperature is more preferably 53°C or more, further preferably 55°C or more, and most preferably 58°C or more. The difference between the soaking time and the heating time is more preferably 33 seconds or more, further preferably 35 seconds or more, and most preferably 38 seconds or more. The larger the difference between the maximum heating temperature and the soaking temperature, the more beneficial it is. Therefore, in the present invention, no special limitation is imposed on its upper limit. However, the upper limit of the difference between the maximum heating temperature and the soaking temperature can be, for example, 100°C. The larger the difference between the soaking time and the heating time, the more beneficial it is. Therefore, in the present invention, no special limitation is imposed on its upper limit. However, the upper limit of the difference between the soaking time and the heating time can be, for example, 80 seconds. Detailed Description of the Invention

[0077] Hereinafter, the present invention will be described in more detail by way of examples. However, it should be noted that the following examples are only used to illustrate the present invention for more detailed description and are not used to limit the scope of the rights of the present invention. This is because the scope of the rights of the present invention is determined by the content recorded in the claims and the content reasonably deduced therefrom.

[0078] (Examples)

[0079] A slab having the alloy composition shown in Table 1 below was heated at 1150°C, and then the heated slab was hot-rolled at 850°C to obtain a hot-rolled sheet with a thickness of 2.0 mm. Thereafter, the hot-rolled sheet was annealed at 1100°C for 4 minutes and then pickled. Thereafter, the hot-rolled sheet was cold-rolled with a reduction ratio of 87.5% to obtain a cold-rolled sheet with a thickness of 0.25 mm. Thereafter, final annealing was performed under the conditions shown in Table 2 below to manufacture a non-oriented electrical steel sheet. In addition, the conditions shown in Table 2 below are based on the surface temperature of the steel sheet.

[0080] For the non-oriented electrical steel sheet manufactured as described above, the total number density of nitrides and carbides with diameters of 1 - 3 μm was measured using SEM, and the coercive force was measured after magnetization to 2000 A / m. Then, the results are shown in Table 2 below.

[0081] In addition, the coercivity is determined by measuring the hysteresis loop of a 60 mm × 60 mm test piece in the range of -2000 A / m to 2000 A / m using a Single Sheet tester.

[0082] [Table 1]

[0083]

[0084] [Table 2]

[0085]

[0086] As can be seen from Table 1 and Table 2 above, in the case of Invention Examples 1 to 9 that satisfy the alloy composition and manufacturing conditions proposed in the present invention, excellent magnetism can be ensured because the total number density of nitrides and carbides with a diameter of 1 - 3 μm satisfies the condition of 50 / mm 2 or less.

[0087] In Comparative Examples 1 to 11, which do not satisfy the alloy composition or manufacturing conditions proposed in the present invention, it can be seen that the magnetism is at a low level because the total number density of nitrides and carbides with a diameter of 1 - 3 μm does not satisfy the condition of 50 / mm 2 or less.

Claims

1. An non-oriented electrical steel sheet, by weight %, the non-oriented electrical steel sheet contains: Si: 3.3 - 4.3%, Al: 0.8 - 1.7%, Mn: 0.3 - 2.5%, Cr: 0.01 - 0.05%, S: less than 0.005% and except 0%, P: less than 0.01% and except 0%, N: 0.001 - 0.004%, Ti: 0.001 - 0.005%, the balance Fe and other inevitable impurities, the non-oriented electrical steel sheet satisfies the following relational expression 1, The total number density of nitrides and carbides with a diameter of 1 - 3 μm is 50 / mm 2 Hereinafter, [Relational expression 1] 0.02 ≤ Al × Ti / Cr ≤ 0.

8.

2. The non-oriented electrical steel sheet according to claim 1, wherein the non-oriented electrical steel sheet further contains one or more of C: less than 0.005%, Nb: less than 0.005%, and V: less than 0.005%.

3. The non-oriented electrical steel sheet according to claim 1, wherein, the non-oriented electrical steel sheet further contains one or more of Sn: less than 0.1%, Sb: less than 0.1%, Ni: less than 0.05%, Cu: 0.005 - 0.2%, and Zn: less than 0.01%.

4. The non-oriented electrical steel sheet according to claim 1, wherein, the non-oriented electrical steel sheet further contains one or more of Mo: less than 0.03%, B: less than 0.0050%, Ca: less than 0.005%, and Mg: less than 0.005%.

5. The non-oriented electrical steel sheet according to claim 1, wherein, the non-oriented electrical steel sheet further contains one or more of Bi, Pb, Ge, and As, and the contents of Bi, Pb, Ge, and As are respectively less than 0.20% and except 0% or the total amount is less than 0.20% and except 0%.

6. The non-oriented electrical steel sheet according to claim 1, wherein, the coercive force of the non-oriented electrical steel sheet is 40 A / m or less even after magnetization to 2000 A / m.

7. A method for manufacturing a non-oriented electrical steel sheet, characterized in that, The manufacturing method includes the following steps: heating the slab at 1100 - 1250 °C, by weight %, the slab contains: Si: 3.3 - 4.3%, Al: 0.8 - 1.7%, Mn: 0.3 - 2.5%, Cr: 0.01 - 0.05%, S: less than 0.005% and except 0%, P: less than 0.01% and except 0%, N: 0.001 - 0.004%, Ti: 0.001 - 0.005%, the balance Fe and other inevitable impurities, and satisfies the following relational expression 1; hot-rolling the heated slab at 800 - 1000 °C to obtain a hot-rolled sheet; cold-rolling the hot-rolled sheet with a reduction ratio of 70 - 95% to obtain a cold-rolled sheet; performing final annealing on the cold-rolled sheet, wherein, the final annealing includes the processes of heating and soaking, the maximum heating temperature is more than 50 °C higher than the soaking temperature, and the soaking time is more than 30 seconds longer than the heating time, [Relational expression 1] 0.02 ≤ Al × Ti / Cr ≤ 0.

8.

8. The method for manufacturing a non-oriented electrical steel sheet according to claim 7, wherein, the slab further contains one or more of C: less than 0.005%, Nb: less than 0.005%, and V: less than 0.005%.

9. The manufacturing method of the non-oriented electrical steel sheet according to claim 7, wherein, the slab further contains one or more of Sn: less than 0.1%, Sb: less than 0.1%, Ni: less than 0.05%, Cu: 0.005 - 0.2%, and Zn: less than 0.01%.

10. The manufacturing method of the non-oriented electrical steel sheet according to claim 7, wherein, The slab further comprises one or more of Mo: below 0.03%, B: below 0.0050%, Ca: below 0.005% and Mg: below 0.005%.

11. The manufacturing method of the non-oriented electrical steel sheet according to claim 7, wherein, The slab further comprises one or more of Bi, Pb, Ge and As, and the contents of Bi, Pb, Ge and As are respectively below 0.20% and excluding 0% or the total amount is below 0.20% and excluding 0%.

12. The manufacturing method of the non-oriented electrical steel sheet according to claim 7, wherein, After the step of obtaining the hot-rolled sheet, it further includes the step of annealing the hot-rolled sheet at 850 - 1150 °C.

13. The manufacturing method of the non-oriented electrical steel sheet according to claim 7, wherein, The cold rolling is carried out once or twice.

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