Non-oriented electrical steel sheet and its manufacturing method

Abstract

An object of the present invention is to provide a non-oriented electrical steel sheet having excellent magnetic properties and a method for producing the same. [Solution] The non-oriented electrical steel sheet of the present invention contains, by weight %, 3.3 to 4.3% Si, 0.8 to 1.7% Al, 0.3 to 2.5% Mn, 0.01 to 0.05% Cr, 0.005% or less (excluding 0%) S, 0.01% or less (excluding 0%) P, 0.001 to 0.004% N, 0.001 to 0.005% Ti, the balance being Fe and other unavoidable impurities, and satisfies the following relational expression 1, and has a total density of nitrides and carbides having a diameter of 1 to 3 μm of 50 particles / mm 2 The present invention is characterized by the following: [Relationship 1] 0.02≦Al×Ti / Cr≦0.8

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 motor cores and the like, and a method for manufacturing the same. [Background technology]

[0002] Recently, in response to the increasing number of disasters caused by climate change, countries around the world have announced roadmaps for achieving carbon neutrality by 2050. Total carbon emissions in 2020 reached 39 billion tons, of which emissions from internal combustion engines accounted for 24%, or 9.4 billion tons. Therefore, there is a great demand for achieving carbon neutrality in this sector through the electrification of internal combustion engines. As a result, electrification is rapidly progressing in the mobility sector, with electric vehicles at the forefront. In new mobility vehicles, the drive motors required to achieve increased mileage and higher top speeds are directly related to the low iron loss characteristics of electrical steel sheets. Low iron loss in electrical steel sheets improves efficiency, thereby further increasing mileage. Therefore, low iron loss is essential for electrical steel sheets. To achieve this, electrical steel sheets typically contain large amounts of Si, Al, and Mn to ensure low iron loss at high frequencies.

[0003] However, impurities present in steel form precipitates such as nitrides and carbides, which impede grain growth and magnetic domain movement, resulting in poor core loss. Therefore, it is necessary to control precipitates that impede grain growth and magnetic domain movement in order to improve magnetic properties. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a non-oriented electrical steel sheet having excellent magnetic properties and a method for producing the same. [Means for solving the problem]

[0005] The non-oriented electrical steel sheet of the present invention comprises, by weight %, 3.3 to 4.3% Si, 0.8 to 1.7% Al, 0.3 to 2.5% Mn, 0.01 to 0.05% Cr, 0.005% or less (excluding 0%) S, 0.01% or less (excluding 0%) P, 0.001 to 0.004% N, 0.001 to 0.005% Ti, the balance being Fe and other inevitable impurities, and satisfies the following relational expression 1, and has a total number density of nitrides and carbides having a diameter of 1 to 3 μm of 50 particles / mm 2 The present invention is characterized by the following:

[0006] [Equation 1] 0.02≦Al×Ti / Cr≦0.8

[0007] 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.

[0008] 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 to 0.2%, and Zn: 0.01% or less.

[0009] 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.

[0010] The non-oriented electrical steel sheet may further contain one or more of Bi, Pb, Ge and As in an amount of 0.20% or less (excluding 0%), either individually or in total.

[0011] The non-oriented electrical steel sheet can have a coercive force of 40 A / m or less even after being magnetized up to 2000 A / m.

[0012] The non-oriented electrical steel sheet of the present invention is produced by forming 11 slabs containing, by weight, 3.3 to 4.3% Si, 0.8 to 1.7% Al, 0.3 to 2.5% Mn, 0.01 to 0.05% Cr, 0.005% or less (excluding 0%) S, 0.01% or less (excluding 0%) P, 0.001 to 0.004% N, 0.001 to 0.005% Ti, the balance being Fe and other unavoidable impurities, and satisfying the following relational expression 1: a step of heating the slab at 800 to 1250°C; a step of finish hot rolling the heated slab at 800 to 1000°C to obtain a hot-rolled sheet; a step of cold rolling the hot-rolled sheet at a rolling reduction of 70 to 95% to obtain a cold-rolled sheet; and a step of final annealing the cold-rolled sheet, wherein the final annealing includes a heating and soaking process, and the maximum 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.

[0013] [Equation 1] 0.02≦Al×Ti / Cr≦0.8

[0014] 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.

[0015] 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 to 0.2%, and Zn: 0.01% or less.

[0016] 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.

[0017] The slab may further contain one or more of Bi, Pb, Ge and As in an amount of 0.20% or less (excluding 0%), either individually or in total.

[0018] After obtaining the hot-rolled sheet, the method may further include annealing the hot-rolled sheet at 850 to 1150°C.

[0019] The cold rolling can be carried out once or twice. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a non-oriented electrical steel sheet having excellent magnetic properties and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0021] To improve the iron loss of non-oriented electrical steel sheets, large amounts of Si, Al, and Mn, which increase resistivity, must be added. However, precipitates that hinder grain growth and magnetic domain migration must also be actively controlled. In particular, fine precipitates such as nitrides and carbides precipitate at grain boundaries and degrade iron loss. Therefore, the inventors recognized that it is possible to manufacture non-oriented electrical steel sheets with excellent magnetic properties by optimizing alloy elements that affect precipitate formation and controlling the temperature and time of the heating zone and soaking zone during the final annealing process, among other manufacturing conditions, to control precipitates and thereby achieve the present invention.

[0022] 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. The content of the alloy composition described below means weight percent unless otherwise specified.

[0023] Si: 3.3 to 4.3% Si is an element that increases the resistivity of a material and reduces iron loss. If the Si content is less than 3.3%, the effect of improving high-frequency iron loss is slight. If the Si content exceeds 4.3%, productivity and punchability may deteriorate due to increased hardness. Therefore, the Si content is preferably in the range of 3.3 to 4.3%. The lower limit of the Si content is more preferably 3.35%, and even more preferably 3.40%. The upper limit of the Si content is more preferably 4.25%, and even more preferably 4.20%.

[0024] Al: 0.8 to 1.7% Al is an element that increases the resistivity of the material and reduces iron loss. If the Al content is less than 0.8%, the high-frequency iron loss is not reduced, and fine nitrides are formed, deteriorating magnetic properties. If the Al content exceeds 1.7%, the physical properties of the mold flux change during the continuous casting process, significantly reducing productivity. Therefore, the Al content is preferably in the range of 0.8 to 1.7%. The lower limit of the Al content is more preferably 0.85%, and even more preferably 0.90%. The upper limit of the Al content is more preferably 1.65%, and even more preferably 1.60%.

[0025] Mn: 0.3 to 2.5% Mn is an element that increases the resistivity of the material, improves core loss, and forms sulfides. If the Mn content is less than 0.3%, MnS precipitates finely, degrading magnetic properties. If the Mn content exceeds 2.5%, it promotes the formation of a

[0111] texture, which is unfavorable to magnetic properties, resulting in a rapid decrease in magnetic flux density. Therefore, the Mn content is preferably in the range of 0.3 to 2.5%. The lower limit of the Mn content is more preferably 0.35%, even more preferably 0.40%, and most preferably 0.45%. The upper limit of the Mn content is more preferably 2.45%, even more preferably 2.40%, and most preferably 2.35%.

[0026] Cr: 0.01 to 0.05% Cr can cause segregation without directly forming precipitates. However, it can also form solid solutions with Al, Ti, etc. through various temperature changes during the manufacturing process, forming intermetallic compounds that can impede magnetic domain movement like precipitates and degrade magnetic properties. If the Cr content is less than 0.01%, it is difficult to achieve a sufficient segregation effect. If the Cr content is more than 0.05%, a large amount of intermetallic compounds will form, causing a deterioration in magnetic properties.

[0027] S: 0.005% or less (excluding 0%) S reacts with Mn, Cu, etc. to form sulfides, which deteriorate the magnetic properties, so the content must be controlled to 0.005% or less.

[0028] P: 0.01% or less (excluding 0%) P inhibits grain boundary bonding, increasing brittleness and reducing rolling productivity. In particular, in steels containing 3.2% or more Si, its content must be controlled to 0.01% or less.

[0029] N: 0.001 to 0.004% N reacts with Al, Ti, etc. to form fine nitrides. Because N present in the atmosphere dissolves into steel, controlling the N content to less than 0.001% excessively increases process costs. If the N content exceeds 0.004%, excessive nitrides are formed, deteriorating grain growth and magnetic properties. The lower limit of the N content is more preferably 0.0012%, even more preferably 0.0014%, and most preferably 0.0016%. The upper limit of the N content is more preferably 0.0035%, even more preferably 0.0030%, and most preferably 0.0025%.

[0030] Ti: 0.001 to 0.005% Ti forms many types of fine precipitates, such as nitrides and carbides. Controlling the Ti content to less than 0.001% increases the process cost excessively. If the Ti content exceeds 0.005%, a large amount of precipitates are formed, making it impossible to obtain an appropriate grain size.

[0031] The remaining component is iron (Fe). However, in a normal manufacturing process, unintentional impurities may be inevitably mixed in from the raw materials or the surrounding environment, and this cannot be excluded. Since these impurities are known to anyone skilled in the normal manufacturing process, not all of the contents thereof are specifically mentioned in this specification.

[0032] The non-oriented electrical steel sheet of the present invention may further contain one or more of C: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

[0033] C: 0.005% or less C reacts with N, Ti, Nb, V, etc. to form fine carbides, which play a role in hindering the growth of crystal grains and the movement of magnetic domains, so its upper limit is limited to 0.005%. More specifically, the C content may be 0.0001 to 0.005%. Even more specifically, the C content may be 0.0005 to 0.003%.

[0034] Nb: 0.005% or less Nb combines with C, N, etc. to form fine nitrides, which plays a role in preventing the movement of magnetic domains, so its upper limit is limited to 0.005%. More specifically, the Nb content may be 0.0001 to 0.005%. Even more specifically, the Nb content may be 0.0005 to 0.003%.

[0035] V:0.005% or less V combines with C, N, etc. to form fine nitrides, which plays a role in preventing the movement of magnetic domains, so its upper limit is limited to 0.005%. More specifically, the V content may be 0.0001 to 0.005%. Even more specifically, the V content may be 0.0005 to 0.003%.

[0036] 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 to 0.2%, and Zn: 0.01% or less.

[0037] Sn: 0.1% or less Sn is an element that segregates at grain boundaries and is added to suppress the diffusion of nitrogen through the grain boundaries, suppress the {111} texture that is detrimental to magnetic properties, and increase the advantageous {100} texture, thereby improving magnetic properties. If the Sb content exceeds 0.1%, it will hinder grain growth, reducing magnetic properties and resulting in poor rolling properties. More specifically, the Sn content may be 0.001 to 0.1%. Even more specifically, the Sn content may be 0.005 to 0.08%.

[0038] Sb: 0.1% or less Sb is an element that segregates at grain boundaries and is added to suppress the diffusion of nitrogen through grain boundaries, suppress the {111} texture that is detrimental to magnetic properties, and increase the advantageous {100} texture, thereby improving magnetic properties. If the Sb content exceeds 0.1%, it will hinder grain growth, reducing magnetic properties and resulting in poor rolling properties. Specifically, the Sb content may be 0.001 to 0.1%. Even more specifically, the Sb content may be 0.005 to 0.08%.

[0039] Ni: 0.05% or less Ni reacts with impurity elements to form fine sulfides, carbides, and nitrides, which have a detrimental effect on magnetic properties, so the upper limit is set to 0.05%. Specifically, the Ni content may be 0.0001 to 0.050%. Even more specifically, the Ni content may be 0.001 to 0.030%.

[0040] Cu: 0.005 to 0.2% Cu plays a role in forming sulfides together with Mn. If the Cu content is less than 0.005%, fine (Cu Mn)S precipitates, which may deteriorate the magnetic properties. If the Cu content exceeds 0.2%, high-temperature embrittlement may occur, which may cause cracks during continuous casting or hot rolling. Specifically, the Cu content may be 0.010 to 0.1%.

[0041] Zn: 0.01% or less Zn acts as an impurity and may deteriorate magnetic properties, so its upper limit is set to 0.01%. Specifically, the Zn content may be 0.0001 to 0.01%. Even more specifically, the Zn content may be 0.001 to 0.008%.

[0042] 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.

[0043] These react with the unavoidably contained C, S, N, etc. to form fine carbides, nitrides, or sulfides, which may have an adverse effect on magnetic properties, so the upper limit can be set as described above.

[0044] The non-oriented electrical steel sheet of the present invention may further contain one or more of Bi, Pb, Ge and As in an amount of 0.20% or less (excluding 0%), either individually or in total.

[0045] When the above-mentioned elements are added, they segregate at the grain boundaries, alleviating stress concentration at the grain boundaries during cold rolling, and in the subsequent recrystallization annealing process, <111> / / Improves magnetic flux density by suppressing recrystallization of ND-oriented crystal grains. When these elements are added appropriately, the above effects can be further achieved. However, excessive amounts can cause significant segregation, suppressing grain growth and potentially deteriorating magnetic flux density and core loss. More specifically, the alloy may contain one or more of Bi, Pb, Ge, and As, each in an amount ranging from 0.0001 to 0.20%. Specifically, the alloy may contain one or more of Bi, Pb, Ge, and As, each in an amount ranging from 0.001 to 0.10%.

[0046] The non-oriented cold rolled steel sheet of the present invention preferably satisfies the above-mentioned alloy composition and also satisfies the following relational expression 1.

[0047] [Equation 1] 0.02≦Al×Ti / Cr≦0.8

[0048] Depending on the heat treatment conditions, Al, Cr, and Ti may promote the formation of precipitates or form solid solutions. Therefore, by appropriately adjusting the heat treatment conditions, the size and fraction of precipitates can be controlled. If the Al×Ti / Cr value is less than 0.02, the Cr content is excessive, resulting in the formation of Cr-based intermetallic compounds, which deteriorates the magnetic properties. If the Al×Ti / Cr value exceeds 0.8, the Al or Ti content is excessively high, making it impossible to control the precipitates. The lower limit of the Al×Ti / Cr value is more preferably 0.025, even more preferably 0.03, and most preferably 0.035. The upper limit of the Al×Ti / Cr value is more preferably 0.75, even more preferably 0.7.

[0049] The non-oriented cold rolled steel sheet of the present invention has a total density of nitrides and carbides having a diameter of 1 to 3 μm of 30 particles / mm 2 It is preferable that the total number density of the nitrides and carbides having a diameter of 1 to 3 μm is 50 pieces / mm or less. Fine nitrides and carbides having a diameter of 1 to 3 μm hinder the growth of crystal grains and the movement of magnetic domains, thereby deteriorating the magnetic properties. Therefore, it is necessary to minimize such fine nitrides and carbides. 2 When the content is controlled as follows, the growth of crystal grains is improved and the movement of magnetic domains during magnetization becomes easier. The nitrides and carbides can be observed using an SEM, and nitrides are defined as precipitates containing 5% by weight or more of N, and carbides are defined as precipitates containing 5% by weight or more of C.

[0050] The non-oriented electrical steel sheet of the present invention provided as described above may have a coercive force of 40 A / m or less even after magnetization up to 2000 A / m. In the present invention, since a lower coercive force is more advantageous, the lower limit is not particularly limited. However, the lower limit of the coercive force may be, for example, 20 A / m.

[0051] In high-frequency rotating machines, the higher the resistivity, the better for reducing eddy-current loss, but if it is too high, the magnetic flux density may decrease. The non-oriented electrical steel sheet of the present invention may have a resistivity of 55 to 85 μΩcm. Meanwhile, the resistivity can be estimated from 13.25 + 11.3 × (Si + Al + Mn / 2).

[0052] Hereinafter, a method for producing a non-oriented electrical steel sheet according to one embodiment of the present invention will be described.

[0053] First, a slab satisfying the above-described alloy composition and Relational Formula 1 is heated at 1100 to 1250°C. If the slab heating temperature is less than 1100°C, the rolling temperature is too low and the slab cannot be rolled to the desired thickness. If the slab heating temperature exceeds 1250°C, fine inclusions precipitate during rolling, deteriorating the magnetic properties. Therefore, the slab heating temperature is preferably in the range of 1100 to 1250°C. The lower limit of the slab heating temperature is more preferably 1110°C, even more preferably 1120°C, and most preferably 1130°C. The upper limit of the slab heating temperature is more preferably 1230°C, even more preferably 1210°C, and most preferably 1190°C.

[0054] The heated slab is then finish hot rolled at 800 to 1000°C to obtain a hot-rolled sheet. If the finish hot rolling temperature is less than 800°C, there is a drawback in that the rolling load becomes excessively high. If the finish hot rolling temperature exceeds 1000°C, there is a drawback in that shape control becomes difficult. The lower limit of the finish hot rolling temperature is more preferably 820°C, even more preferably 840°C, and most preferably 850°C. The upper limit of the finish hot rolling temperature is more preferably 980°C, even more preferably 960°C, and most preferably 950°C.

[0055] After obtaining the hot-rolled sheet, the hot-rolled sheet may be annealed at 850 to 1150°C. The hot-rolled sheet annealing process can increase the crystal orientation advantageous for magnetic properties. If the hot-rolled sheet annealing temperature is less than 850°C, the crystal grains may not grow or may grow finely, which may reduce the effect of increasing the magnetic flux density. If the hot-rolled sheet annealing temperature is more than 1150°C, the magnetic properties may deteriorate and the rolling workability may be reduced due to deformation of the sheet shape. Therefore, the hot-rolled sheet annealing temperature may be in the range of 850 to 1150° C. The lower limit of the hot-rolled sheet annealing temperature is more preferably 870° C., even more preferably 890° C., and most preferably 910° C. The upper limit of the hot-rolled sheet annealing temperature is more preferably 1140° C., even more preferably 1130° C., and most preferably 1120° C. On the other hand, the above-mentioned hot-rolled sheet annealing can be omitted.

[0056] The hot-rolled sheet is then cold-rolled at a reduction of 70 to 95% to obtain a cold-rolled sheet. If the cold-rolling reduction is less than 70%, the deformation structure is non-uniform, which may result in a large magnetic deviation in the final product. If the cold-rolling reduction is more than 95%, a texture unfavorable to magnetism may develop, which may result in a deterioration in the magnetic properties of the final product. Therefore, the cold rolling reduction is preferably in the range of 70 to 95%. The lower limit of the cold rolling reduction is more preferably 72%, even more preferably 74%, and most preferably 76%. The upper limit of the cold rolling reduction is more preferably 93%, even more preferably 91%, and most preferably 89%. The cold rolling can be performed once or twice to obtain the target thickness.

[0057] The cold-rolled sheet is then subjected to final annealing, which includes heating and soaking, and the maximum heating temperature is preferably 50°C or more higher than the soaking temperature, and the soaking time is preferably 30 seconds or more longer than the heating time. The reason for controlling the heating temperature to a high level is to redissolve fine precipitates such as nitrides and carbides. The reason for controlling the soaking temperature to a low level is to suppress the growth of crystal grains and improve high-frequency iron loss. The reason for making the soaking time longer than the heating time is to reduce the non-uniformity of the crystal grain size and minimize the magnetic deviation.

[0058] If the difference between the maximum heating temperature and the soaking temperature is less than 50°C, or if the difference between the soaking time and the heating time is less than 30 seconds, it is difficult to fully obtain the above-mentioned effects. The difference between the maximum heating temperature and the soaking temperature is more preferably 53°C or more, even more 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, even more preferably 35 seconds or more, and most preferably 38 seconds or more. The greater the difference between the maximum heating temperature and the soaking temperature, the more advantageous it is, and therefore the present invention does not particularly limit the upper limit. However, as an example, the upper limit of the difference between the maximum heating temperature and the soaking temperature may be 100°C. The greater the difference between the soaking time and the heating time, the more advantageous it is, and therefore the present invention does not particularly limit the upper limit. However, as an example, the upper limit of the difference between the soaking time and the heating time may be 80 seconds. [Example]

[0059] The present invention will be described in more detail below with reference to examples. However, it should be noted that the following examples are intended to illustrate and explain the present invention in more detail, and are not intended to limit the scope of the present invention. The scope of the present invention is determined by the matters described in the claims and matters that can be reasonably inferred therefrom.

[0060] (Example) A slab having the alloy composition shown in Table 1 below was heated at 1150°C, and then the heated slab was finish hot-rolled at 850°C to obtain a hot-rolled sheet with a thickness of 2.0 mm. The hot-rolled sheet was then annealed at 1100°C for 4 minutes and pickled. The hot-rolled sheet was then cold-rolled at a reduction of 87.5% to obtain a cold-rolled sheet with a thickness of 0.25 mm. This was then final-annealed under the conditions shown in Table 2 below to produce a non-oriented electrical steel sheet. The conditions shown in Table 2 below were based on the surface temperature of the steel sheet.

[0061] The total number density of nitrides and carbides having a diameter of 1 to 3 μm was measured using an SEM for the non-oriented electrical steel sheets manufactured in this manner, and the coercive force was measured after magnetization up to 2000 A / m. The results are shown in Table 2 below.

[0062] On the other hand, the coercive force was determined by measuring the hysteresis loop in the range of −2000 A / m to 2000 A / m using a single sheet tester using a 60 mm×60 mm test piece.

[0063] [Table 1]

[0064] [Table 2]

[0065] As shown in Tables 1 and 2 above, in the case of Examples 1 to 9 that satisfy the alloy composition and manufacturing conditions proposed by the present invention, the total number density of nitrides and carbides having a diameter of 1 to 3 μm was 50 / mm 2 The fact that the following conditions are met indicates that excellent magnetic properties are ensured.

[0066] Comparative Examples 1 to 11 are cases where the alloy composition or manufacturing conditions proposed by the present invention are not satisfied, and the total density of nitrides and carbides having a diameter of 1 to 3 μm is 50 pieces / mm 2 The fact that the following conditions are not met indicates that the magnetism is at a low level.

Claims

1. The alloy consists of, in weight percent, Si: 3.3 to 4.3%, Al: 0.8 to 1.7%, Mn: 0.3 to 2.5%, Cr: 0.01 to 0.05%, S: 0.005% or less (excluding 0%), P: 0.01% or less (excluding 0%), N: 0.001 to 0.004%, Ti: 0.001 to 0.005%, the balance being Fe and other unavoidable impurities, The following relational expression 1 is satisfied: The total density of nitrides and carbides with a diameter of 1 to 3 μm is 50 pieces / mm ２ A non-oriented electrical steel sheet characterized by the following: [Relationship 1] 0.02≦Al×Ti / Cr≦0.8

2. The non-oriented electrical steel sheet according to claim 1, further comprising at least one of C: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

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

4. 2. The non-oriented electrical steel sheet according to claim 1, further comprising 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.

5. 2. The non-oriented electrical steel sheet according to claim 1, further comprising one or more of Bi, Pb, Ge, and As in an amount of 0.20% or less (excluding 0%), respectively or in a total amount thereof.

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

7. a step of heating a slab consisting of, in weight percent, 3.3 to 4.3% Si, 0.8 to 1.7% Al, 0.3 to 2.5% Mn, 0.01 to 0.05% Cr, 0.005% or less (excluding 0%) S, 0.01% or less (excluding 0%) P, 0.001 to 0.004% N, 0.001 to 0.005% Ti, the balance being Fe and other unavoidable impurities, and satisfying the following relational expression 1, at 1100 to 1250°C; finish hot rolling the heated slab at 800 to 1000°C to obtain a hot-rolled sheet; cold-rolling the hot-rolled sheet at a reduction rate of 70 to 95% to obtain a cold-rolled sheet; final annealing of the cold-rolled sheet; The final annealing includes heating and soaking, the maximum heating temperature being 50°C or more higher than the soaking temperature, and the soaking time being 30 seconds or more longer than the heating time. [Relationship 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 at least one of C: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

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

10. The method for manufacturing a non-oriented electrical steel sheet according to claim 7, wherein the slab further contains 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.

11. 8. The method for producing a non-oriented electrical steel sheet according to claim 7, wherein the slab further contains one or more of Bi, Pb, Ge, and As in an amount of 0.20% or less (excluding 0%), respectively or in a total amount thereof.

12. The method for manufacturing a non-oriented electrical steel sheet according to claim 7, further comprising the step of annealing the hot-rolled sheet at 850 to 1150°C after the step of obtaining the hot-rolled sheet.

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

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