Non-oriented electrical steel sheet and method for manufacturing same

Abstract

A non-oriented electrical steel sheet according to an embodiment of the present invention contains, in wt%, 1.5-5.0% of Si, 0.1-3.0% of Al, and 0.1-3.0% of Mn, with the remainder comprising Fe and inevitable impurities. At the 1 / 4 point of the total thickness from the surface of the non-oriented electrical steel sheet in the thickness direction, the random intensity ratio of the {100}<011> orientation is 2 or greater, and the random intensity ratio of the {411}<148> orientation is 4 or less.

Description

Non-oriented electrical steel sheet and method of manufacturing the same

[0001] One embodiment of the present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same. Specifically, one embodiment of the present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same, wherein a specific texture is developed by controlling the annealing conditions of a hot-rolled sheet and a cold-rolled sheet to improve the circumferential magnetism of a motor.

[0002] Non-oriented electrical steel is primarily used in motors that convert electrical energy into mechanical energy, and excellent magnetic properties are required to achieve high efficiency in this process. In particular, with the recent rise in interest in eco-friendly vehicles driven by motors instead of internal combustion engines, the demand for non-oriented electrical steel used as core materials for drive motors is increasing, and to meet this demand, non-oriented electrical steel with excellent magnetic properties and strength is required.

[0003] The magnetic properties of non-oriented electrical steel are primarily evaluated based on iron loss and magnetic flux density. Iron loss refers to the energy loss occurring at a specific magnetic flux density and frequency, while magnetic flux density refers to the degree of magnetization obtained under a specific magnetic field. Lower iron loss allows for the manufacture of motors with higher energy efficiency under the same conditions, whereas higher magnetic flux density enables motor miniaturization or reduced copper loss. Therefore, by utilizing non-oriented electrical steel with low iron loss and high magnetic flux density, drive motors with excellent efficiency and torque can be produced, thereby improving the driving range and power output of eco-friendly vehicles.

[0004] The characteristics of non-oriented electrical steel sheets that must be considered also vary depending on the motor's operating conditions. A widely used general standard for evaluating the characteristics of non-oriented electrical steel sheets used in motors is W15 / 50, which represents the iron loss when a 1.5T magnetic field is applied at a commercial frequency of 50Hz. However, for non-oriented electrical steel sheets with a thickness of 0.35mm or less used in drive motors for eco-friendly vehicles, magnetic properties are often critical at low fields of 1.0T or less and high frequencies above 400Hz; therefore, W 10 / 400 The characteristics of non-oriented electrical steel sheets are often evaluated based on iron loss.

[0005] A commonly used method to improve the magnetic properties of non-oriented electrical steel is to add alloying elements such as Si, Al, and Mn. Increasing the resistivity of the steel through the addition of these alloying elements reduces eddy current losses, thereby lowering overall iron loss. Additionally, the alloying elements dissolve into the iron as substitutional elements, causing a strengthening effect that can increase strength. On the other hand, increasing the amount of alloying elements such as Si, Al, and Mn has the disadvantage of degrading magnetic flux density and increasing brittleness; furthermore, adding more than a certain amount makes cold rolling impossible, rendering commercial production unfeasible. In particular, while electrical steel exhibits superior high-frequency iron loss as its thickness is reduced, the deterioration in rollability caused by brittleness becomes a critical issue. The maximum combined content of Si, Al, and Mn suitable for commercial production is known to be approximately 4.5 wt%; additionally, by optimizing the content of trace elements, it is possible to produce top-grade non-oriented electrical steel with excellent magnetic properties and strength.

[0006] To this end, a method to improve properties by thinning the hot-rolled plate has been proposed, and a method to improve magnetism by including Al and undergoing double annealing and double rolling has been proposed. In addition, a method to thin the hot-rolled plate through a thin slab manufacturing method has been proposed.

[0007] However, methods to reduce the thickness of hot-rolled plates may increase the rolling load in the general hot-rolling process and cause process load by increasing the annealing time during the subsequent continuous annealing of hot-rolled plates, and while some improvement in magnetism is confirmed with high Al addition and the double annealing and double rolling processes, {110} <001> As the Goss texture also develops, the motor's circumferential characteristics deteriorate, and surface defects due to high Al addition also increase significantly.

[0008] One embodiment of the present invention provides a non-oriented electrical steel sheet and a method for manufacturing the same. Specifically, one embodiment of the present invention provides a non-oriented electrical steel sheet and a method for manufacturing the same, in which the circumferential magnetism of the steel sheet is improved by developing a specific texture through controlling the annealing conditions of the hot-rolled sheet and the cold-rolled sheet.

[0009] A non-oriented electrical steel sheet according to one embodiment of the present invention comprises, in weight percent, Si: 1.5 to 5.0%, Al: 0.1 to 3.0%, Mn: 0.1 to 3.0%, the remainder being Fe and unavoidable impurities, and {100} at a point 1 / 4 of the total thickness in the thickness direction from the surface. <011> The random intensity ratio of the orientation is 2 or greater and {411} <148> The random intensity ratio of the orientation is 4 or less.

[0010] In addition, a non-oriented electrical steel sheet according to one embodiment of the present invention is <111> The area fraction of grains parallel to the ND direction of the steel sheet within 15° is 25% or less, and <110> for the area fraction of grains parallel to the ND direction of the steel sheet within 15° <100> The ratio of the area fraction of grains parallel to the ND direction of the steel plate within 15° can be 0.5 to 5.

[0011] <100> The area fraction of grains parallel to the ND direction of the steel plate within 15° may be 10% or more.

[0012] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

[0013] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include 0.005 to 0.200 weight% of one or more of Sn, Sb, Bi, Pb, Ge, and As, respectively or in their combined amount.

[0014] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Cu: 0.2 wt% or less, Cr: 0.5 wt% or less, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

[0015] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Mo: 0.03 wt% or less, B: 0.01 wt% or less, V: 0.01 wt% or less, Ca: 0.01 wt% or less, Nb: 0.01 wt% or less, Zr: 0.01 wt% or less, Te: 0.01 wt% or less, and Mg: 0.01 wt% or less.

[0016]

[0017] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention comprises: a step of manufacturing a hot-rolled steel sheet by hot-rolling a slab containing, in weight%, Si: 1.5 to 5.0%, Al: 0.1 to 3.0%, Mn: 0.1 to 3.0%, and the remainder being Fe and unavoidable impurities; a hot-rolled sheet annealing step of annealing the hot-rolled steel sheet; a step of manufacturing a cold-rolled sheet by cold-rolling the annealed hot-rolled steel sheet; and a cold-rolled sheet annealing step of annealing the cold-rolled sheet.

[0018] In the hot-rolled plate annealing stage, the plate is annealed at a cracking temperature of 650 to 850°C for 1 to 40 hours, and in the cold-rolled plate annealing stage, the dew point temperature (DPH) in the heating stage of 300 to 800°C is -10°C or lower, and the difference between the dew point temperature (DPH) in the heating stage and the dew point temperature (DPS) in the cracking stage may be 20°C or more.

[0019] The slab may further include one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

[0020] The slab may further contain 0.005 to 0.200 weight% of one or more of Sn, Sb, Bi, Pb, Ge, and As, either individually or in their combined amount.

[0021] The slab may further include one or more of Cu: 0.2 wt% or less, Cr: 0.5 wt% or less, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

[0022] The slab may further include one or more of Mo: 0.03 wt% or less, B: 0.01 wt% or less, V: 0.01 wt% or less, Ca: 0.01 wt% or less, Nb: 0.01 wt% or less, Zr: 0.01 wt% or less, Te: 0.01 wt% or less, and Mg: 0.01 wt% or less.

[0023] In the hot-rolled steel sheet manufacturing stage, the hot-rolled steel sheet is wound into a coil, and the wound coil can be batch annealed in the hot-rolled steel sheet annealing stage.

[0024] In the hot-rolled steel sheet manufacturing stage, the hot-rolled steel sheet can be cooled to 600 to 800°C, and then annealed in the hot-rolled steel sheet annealing stage.

[0025] During the cold rolling stage, the temperature of the steel sheet can be 100 to 400℃.

[0026] In the cold rolling step, the diameter of the work roll can be 70 to 400 mm.

[0027] During the annealing stage of the cold-rolled sheet, the cracking temperature can be 800 to 1050℃.

[0028] A non-oriented electrical steel sheet according to one embodiment of the present invention has excellent magnetic flux density in the circumferential direction.

[0029] Ultimately, the non-oriented electrical steel sheet according to one embodiment of the present invention contributes to the manufacture of eco-friendly automobile motors, high-efficiency home appliance motors, and super-premium electric motors.

[0030] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention.

[0031] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0032] When it is stated that one part is "above" or "on" another part, it may be directly above or on the other part, or other parts may be involved in between. In contrast, when it is stated that one part is "directly above" another part, no other parts are interposed in between.

[0033] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0034] In one embodiment of the present invention, the meaning of including additional elements is that the remainder of iron (Fe) is replaced by an amount of the additional element.

[0035] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0036] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0037] A non-oriented electrical steel sheet according to one embodiment of the present invention comprises, in weight percent, Si: 1.5 to 5.0%, Al: 0.1 to 3.0%, Mn: 0.1 to 3.0%, and the remainder being Fe and unavoidable impurities.

[0038] Below, we will explain the reason for limiting the composition of non-oriented electrical steel sheets.

[0039] Si: 1.5 to 5.0 wt%

[0040] Silicon (Si) plays a role in increasing the resistivity of the material to lower iron loss and increasing strength through solid solution strengthening. If too little Si is added, the effect of improving iron loss and strength may be insufficient. If too much Si is added, the brittleness of the material increases, causing a sharp decrease in rolling productivity and potentially forming a surface oxide layer and oxides that are harmful to magnetism. Therefore, Si may be included in an amount of 1.5 to 5.0 weight%. More specifically, it may be included in an amount of 2.0 to 4.5 weight%. Even more specifically, it may be included in an amount of 3.0 to 4.2 weight%.

[0041] Al: 0.1 to 3.0 wt%

[0042] Aluminum (Al) plays a role in increasing the resistivity of the material to lower iron loss and increasing strength through solid solution strengthening. If too little Al is added, fine nitrides may form, making it difficult to obtain the effect of improving magnetism. If too much Al is added, excessive nitrides are formed, degrading magnetism and causing problems in all processes, such as steelmaking and continuous casting, which can significantly reduce productivity. Therefore, Al may be included in an amount of 0.1 to 3.0 weight%. More specifically, it may be included in an amount of 0.3 to 2.0 weight%. Even more specifically, it may be included in an amount of 0.5 to 1.5 weight%.

[0043] Mn: 0.1 to 3.0 wt%

[0044] Manganese (Mn) plays a role in improving iron loss by increasing the resistivity of the material and forming sulfides. If too little Mn is added, fine sulfides are formed, causing magnetic degradation; if too much Mn is added, fine MnS is excessively precipitated, promoting the formation of a {111} texture that is unfavorable to magnetism, which causes a rapid decrease in magnetic flux density. Therefore, Mn may be included in an amount of 0.1 to 3.0 weight%. More specifically, it may be included in an amount of 0.2 to 2.0 weight%. Even more specifically, it may be included in an amount of 0.3 to 1.5 weight%.

[0045] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

[0046] P: 0.1 wt% or less

[0047] Phosphorus (P) can improve magnetic flux density as a grain boundary segregation element, but if added in excessive amounts, it increases the brittleness of the steel plate and impairs weldability. More specifically, it may contain 0.0001 to 0.0500 weight% of P.

[0048] C: 0.005 wt% or less

[0049] Carbon (C) can cause magnetic aging and combine with other impurity elements to form carbides, which can impede grain boundary or domain wall movement and degrade magnetic properties. More specifically, it may contain 0.0001 to 0.003 weight% of C.

[0050] S: 0.005 wt% or less

[0051] Sulfur (S) can form fine precipitates, such as MnS and CuS, which can worsen magnetic properties and hot workability. More specifically, it may contain 0.0001 to 0.0030 weight% of S.

[0052] Ti: 0.005 wt% or less

[0053] Titanium (Ti) has a very strong tendency to form precipitates in steel and can degrade iron loss by forming fine carbides, nitrides, or sulfides within the base material, thereby inhibiting grain growth and domain wall movement. More specifically, it may contain 0.0001 to 0.003 weight% of Ti.

[0054] N: 0.005 wt% or less

[0055] Nitrogen (N) not only forms fine AlN precipitates inside the base material but also combines with other impurities to form fine precipitates, thereby inhibiting grain growth and domain wall movement, which can worsen iron loss. More specifically, it may contain 0.0001 to 0.0030 weight% of N.

[0056]

[0057] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include 0.005 to 0.200 weight% of one or more of Sn, Sb, Bi, Pb, Ge, and As, respectively or in their combined amount.

[0058] Sn and Sb

[0059] Tin (Sn) and antimony (Sb) play a role in suppressing the development of {111} orientations, which degrade magnetism by segregating at the grain boundaries during the initial stage of final recrystallization annealing. If too much Sn and Sb are added, it can hinder the recovery and growth of coarse elongated band structures and degrade surface quality. Therefore, one or more of Sn and Sb may be added within the aforementioned range. More specifically, it may contain 0.005 to 0.200 wt% of Sn or 0.005 to 0.200 wt% of Sb.

[0060] Bi, Pb, Ge, and As

[0061] When bismuth (Bi), lead (Pb), germanium (Ge), and arsenic (As) are added, they segregate at grain boundaries, alleviating stress concentration at grain boundaries during cold rolling, which in the subsequent recrystallization annealing process <111> By suppressing the recrystallization of / ND orientation grains, magnetic flux density is improved. If these are added appropriately, the aforementioned effects can be additionally obtained; however, if included in excessive amounts, a large amount of segregation occurs, which inhibits grain growth and may actually result in inferior magnetic flux density and iron loss.

[0062]

[0063] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Cu: 0.2 wt% or less (excluding 0%), Cr: 0.5 wt% or less (excluding 0%), Ni: 0.05 wt% or less (excluding 0%), Zn: 0.01 wt% or less (excluding 0%), and Co: 0.05 wt% or less (excluding 0%).

[0064] Cu: 0.200 wt% or less

[0065] Copper (Cu) plays a role in forming sulfides together with Mn. If more Cu is added, if too much is added, high-temperature brittleness occurs, which can lead to the formation of cracks during continuous casting or hot rolling. More specifically, it may contain 0.01 to 0.10 weight% of Cu.

[0066] Cr: 0.50 wt% or less

[0067] Chromium (Cr) plays a role in improving iron loss by increasing resistivity. If too much Cr is included, magnetic flux density may decrease. More specifically, it may contain 0.050 to 0.20 weight percent of Cr.

[0068] Ni: 0.05 wt% or less

[0069] Nickel (Ni) can react with impurity elements to form fine sulfides, carbides, and nitrides, which can have a harmful effect on magnetism. More specifically, it may contain 0.001 to 0.03 weight percent of Ni.

[0070] Zn: 0.01 wt% or less

[0071] If the content of zinc (Zn) is excessive, it can act as an impurity and impair magnetism. Therefore, Zn may be added within the aforementioned range. More specifically, Zn may be included in an amount of 0.001 to 0.005 weight%.

[0072] Co: 0.05 wt% or less

[0073] Cobalt (Co) does not form fine precipitates that reduce the magnetism of steel sheets, but it increases high-temperature strength, which can cause the coil shape to be defective after hot rolling.

[0074]

[0075] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Mo: 0.03 wt% or less (excluding 0%), B: 0.0100 wt% or less (excluding 0%), V: 0.0100 wt% or less (excluding 0%), Ca: 0.0100 wt% or less (excluding 0%), Nb: 0.0100 wt% or less (excluding 0%), Zr: 0.0100 wt% or less (excluding 0%), Te: 0.0100 wt% or less (excluding 0%), and Mg: 0.0100 wt% or less (excluding 0%).

[0076] Mo: 0.030 wt% or less

[0077] If molybdenum (Mo) is added in excess, it may suppress the segregation of segregated elements, thereby reducing the texture improvement effect. Therefore, Mo may be included in an amount of 0.03 weight% or less. The lower limit is not specifically limited, but since it plays a role in improving the texture by segregating at the surface and grain boundaries, it may be included in an amount of 0.001 weight% or more. More specifically, Mo may be included in an amount of 0.001 to 0.010 weight%. Even more specifically, Mo may be included in an amount of 0.005 to 0.010 weight%.

[0078] B: 0.0100 wt% or less

[0079] If an excessive amount of boron (B) is added, it may cause deterioration of magnetic properties through the formation of inclusions within the steel. Therefore, B may be included in an amount of 0.005 weight% or less. The lower limit is not specifically limited, but it may be 0.0001 weight% due to steelmaking costs. More specifically, B may be included in an amount of 0.0001 to 0.0050 weight%.

[0080] V: 0.0100 wt% or less

[0081] Vanadium (V) has a very strong tendency to form precipitates in steel and degrades iron loss by forming fine carbides or nitrides inside the base material, thereby inhibiting grain growth and domain wall movement. Therefore, the V content may be 0.0100 wt% or less. The lower limit is not specifically limited, but it may be 0.0003 wt% due to steelmaking costs. That is, V may be included in 0.0003 to 0.0100 wt%. More specifically, V may be included in 0.0003 to 0.0050 wt%.

[0082] Ca: 0.0100 wt% or less

[0083] Calcium (Ca) has a very strong tendency to form precipitates in steel and degrades iron loss by forming fine sulfides inside the base material, thereby inhibiting grain growth and domain wall movement. Therefore, the Ca content may be 0.0100 wt% or less. The lower limit is not specifically limited, but it may be 0.0003 wt% due to steelmaking costs. That is, it may contain 0.0003 to 0.0100 wt% of Ca. More specifically, it may contain 0.0003 to 0.0050 wt% of Ca.

[0084] Nb: 0.0100 wt% or less

[0085] Niobium (Nb) has a very strong tendency to form precipitates in steel and degrades iron loss by forming fine carbides or nitrides within the base material, thereby inhibiting grain growth and domain wall movement. Therefore, the Nb content may be 0.0100 wt% or less. The lower limit is not specifically limited, but it may be 0.0003 wt% due to steelmaking costs. That is, it may contain 0.0003 to 0.0100 wt% of Nb. More specifically, it may contain 0.0003 to 0.0050 wt% of Nb.

[0086] Zr: 0.0100 wt% or less

[0087] If an excessive amount of zirconium (Zr) is added, it may cause deterioration of magnetic properties through the formation of inclusions within the steel. Therefore, Zr may be included in an amount of 0.0100 weight% or less. The lower limit is not specifically limited, but it may be set to 0.0001 weight% due to steelmaking costs. That is, Zr may be included in an amount of 0.0001 to 0.0100 weight%. More specifically, it may be included in an amount of 0.0005 to 0.0050 weight%.

[0088] Te: 0.0100 wt% or less

[0089] Tellurium (Te) can be added to prevent the oxide layer, which is fractured during rolling, from being pressed into the base material and to detach it, as it diffuses into the oxide layer on the surface of the hot-rolled coil, increases the coefficient of friction between the oxide layer and the rolling work roll, and increases hardness by concentrating beneath the oxide layer. If the amount of Te added is too small, the effect may be negligible. If too much Te is added, the oxide layer detaches easily, causing the base material to come into direct contact with the work roll, which reduces the above effect, and excessive deformation bands may be generated within the steel sheet during cold rolling, leading to the development of a {111} / ND texture that is unfavorable to magnetism. More specifically, it may contain 0.0001 to 0.007 weight% of tellurium.

[0090] Mg: 0.0100 wt% or less

[0091] Magnesium (Mg) is an element that primarily combines with S to form sulfides and can affect the surface oxide layer of the base iron. Therefore, Mg may be included in an amount of 0.0100 wt% or less. The lower limit is not specifically limited, but it may be set to 0.0001 wt% due to steelmaking costs. That is, Mg may be included in an amount of 0.0001 to 0.0100 wt%. More specifically, it may be included in an amount of 0.0005 to 0.0050 wt%.

[0092]

[0093] The remainder comprises Fe and unavoidable impurities. The unavoidable impurities are those introduced during the steelmaking stage and the manufacturing process of non-oriented electrical steel sheets; as this is widely known in the field, a detailed description is omitted. In one embodiment of the present invention, the addition of elements other than the aforementioned alloy components is not excluded, and various elements may be included within a scope that does not impair the technical spirit of the present invention. If additional elements are included, they replace the remainder, Fe.

[0094]

[0095] As previously mentioned, in one embodiment of the present invention, the alloy composition of the steel plate can be appropriately adjusted and a specific texture developed to improve magnetism.

[0096] A non-oriented electrical steel sheet according to one embodiment of the present invention is {100} at a point 1 / 4 of the total thickness in the thickness direction from the surface. <011> The random intensity ratio of the orientation is 2 or greater and {411} <148> The random intensity ratio of the orientation is 4 or less.

[0097] In one embodiment of the present invention, the measurement of a specific grain orientation and its area fraction was performed by removing the surface up to 1 / 4 thickness of the steel plate from a cross-section (ND plane) parallel to the rolling plane of the steel plate, and then analyzing the grain orientations of the grains using an electron beam backscatter diffraction (EBSD) measuring instrument equipped with a JEOL JSM-7200F scanning electron microscope on the chemically polished surface, with a measurement interval of 2 μm and a total measurement area of ​​5000 μm × 5000 μm.

[0098] The grain orientations measured by EBSD can be converted into Orientation Distribution Functions (ODF) to represent the texture of the steel sheet. In particular, in the φ2=45° cross-section of the ODF, {100}, which is a feature of this patent <011> and {411} <148> The degree of orientation concentration can be well evaluated. The φ2=45° ODF represents the change in crystal orientation at φ1=0–90° and Φ=0–90° under the fixed condition of φ2=45°. The φ2=45° ODF can be expressed using TSL’s analysis program, OIM Analysis software, based on data obtained using the previously described EBSD measuring device. The detailed analysis conditions are Series Rank [L]:16 / Gaussian Half-Width [degrees]:5. Since most electrical steel sheets have a highly symmetrical body-centered cubic (BCC) structure, sample symmetry was measured as orthotropic (rolled sheet), and the results are expressed under the conditions of Bunge Euler Angles: φ1=0–90°, Φ=0–90°, and φ2=45°. At this time, under the φ2=45° condition, {100} <011> The orientation is the orientation where φ1=0° and Φ=0°, expressed as the relative strength relative to a random specimen. Since it is generally expressed as the relative strength of a specimen measured relative to a random specimen, in this invention it is expressed as the random strength ratio. In addition, {411} <148> The random strength ratio was expressed as the relative strength relative to the random specimen under the condition of φ2=45°, φ1=19.5°, and Φ=19.5°.

[0099] In addition to EBSD measurement and OIM analysis, this type of texture analysis can also be used for ODF analysis by measuring the Inverse Pole Figure of {110}, {100}, and {211} using X-rays, so there are no separate restrictions on the measurement method for obtaining ODF.

[0100] {100} <011> Defense (hereinafter, “{100} <011> The random intensity ratio of the grains (also called “grains”) is 2 or greater. {100} <011> The oriented grains are grains favorable for magnetization at a 45° angle to the rolling direction, and increasing their strength is advantageous for excellent circumferential magnetism. More specifically, {100} <011> The random intensity ratio of the orientation may be 2.5 to 5.5 or less.

[0101] {411} <148> Defense (hereinafter, “{411} <148> The random intensity ratio of the grain (also called) is 4 or less. {411} <148> Orientational grains are grains that are unfavorable to magnetization, and a low intensity is advantageous for magnetism. More specifically, {411} <148> The random intensity ratio of the orientation can be 2.0 to 3.8.

[0102] Meanwhile, a non-oriented electrical steel sheet according to one embodiment of the present invention is <111> Crystal grains parallel to the ND direction of the steel plate within 15° (hereinafter, “ <111> The area fraction of the / ND (also called “crystalline grains”) is 25% or less, and <110> Crystal grains parallel to the ND direction of the steel plate within 15° (hereinafter, “ <110> for the area fraction of the / ND grain (also called "crystal grain") <100> Crystal grains parallel to the ND direction of the steel plate within 15° (hereinafter, “ <100> The ratio of the area fraction of the / ND grain (also called "crystalline grain") <100> / ND Grain / <110> / ND (grain size) can be 0.5 to 5.0.

[0103] Inside the steel plate <111> If there are many crystal grains, magnetization does not easily occur due to an externally applied magnetic field, resulting in lower magnetic flux density and increased iron loss, which does not meet the desired motor efficiency, so this can be minimized. <111> The area fraction of the / ND crystal grains is 25.0% or less. More specifically, it may be 10 to 24%.

[0104] <110> / ND grains are <100> Although it is not an orientation that is as difficult to magnetize as the grain size, it causes large magnetic deviations in the rolling direction and the direction perpendicular to rolling, making it disadvantageous for securing uniform magnetism throughout the entire steel sheet. However, <110> / ND grains are <100> Since it is more advantageous for securing magnetic flux density and low iron loss characteristics than / ND grain size, it is necessary to control it at an appropriate fraction. Therefore, in order to secure uniform magnetism throughout the entire direction of the steel sheet, <100> Increasing the ratio of / ND crystal grains, <110> Magnetism can be further enhanced by lowering the ratio of / ND crystal grains. More specifically <100> / ND Grain / <110> The / ND grain ratio can be set to 0.7 to 4.5.

[0105] <100> The area fraction of grains parallel to the ND direction of the steel plate within 15° may be 10% or more. <100> / ND grains are grains favorable for magnetization, and it is advantageous to secure a large fraction of them. More specifically, <100> / ND grains may be 20.0% or more. More specifically <100> / ND crystal grains can be 20 to 40%.

[0106] At this time, <111> / ND, <110> / ND and <100> / ND are each <111> , <110> and <100> It refers to grains whose direction is parallel to the normal direction of the rolling plane of the steel plate (ND direction) at an angle of 15° or less.

[0107] <111> / ND, <110> / ND and <100> / ND The grain fraction can be measured using a TSL EBSD measuring device mounted on a JEOL Scanning Electron Microscope (model name JSM-7200F) on a cross-section including the rolling direction of the steel sheet. Area fraction refers to the ratio of the area occupied by grains of a specific orientation to the total area of ​​the steel sheet measured by electron backscatter diffraction (EBSD). A range of within 15° means that the angle between the vertical axis of the steel sheet surface and any plane including the corresponding orientation is within 15°, and this can be measured using the Orientation of Matter (OIM) program of the TSL EBSD. More specifically, after removing the surface up to 1 / 4 thickness of the steel plate from a cross-section (ND plane) parallel to the rolling plane of the steel plate, the crystal orientation of the crystal grains was analyzed through electron backscatter diffraction (EBSD) measurements on the chemically polished surface, with a measurement interval of 2 µm and a total measurement area of ​​5000 µm × 5000 µm.

[0108]

[0109] In one embodiment of the present invention, crystal grains having a specific orientation are formed, and the magnetism is uniformly excellent across the entire direction.

[0110] Specifically, a non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy one or more of the following formulas 1 to 3.

[0111] [Equation 1]

[0112] (B50 L + B50 C ) / 2 ≥ 1.65

[0113] [Equation 2]

[0114] (B50 L + B50 C + B50 45° ) / 3 ≥ 1.63

[0115] [Equation 3]

[0116] B50 45° / {(B50 L + B50 C ) / 2} ≥ 0.95

[0117] (However, B50 in Equations 1 to 3) L is the magnetic flux density (B50, Tesla) measured in the rolling direction, and B50 C is the magnetic flux density (B50, Tesla) measured in the direction perpendicular to rolling, and B50 45° represents the magnetic flux density (B50, Tesla) measured in a direction forming a 45° angle with the rolling direction.

[0118] B50 means the magnetic flux density induced in a magnetic field of 5000 A / m.

[0119] Equation 1 is basically a general method for evaluating the magnetic flux density of non-oriented electrical steel sheets and represents the average value of the magnetic flux density (B50) in the rolling direction (L) and the rolling perpendicular direction (C).

[0120] Equation 2 represents the average value of the magnetic flux density (B50) measured in the rolling direction (L), the vertical direction (C) of the steel plate, and the direction forming a 45° angle with respect to the rolling direction. This implies that the magnetic flux density is excellent not only in the conventional rolling direction (L) and the vertical direction (C), but also in the direction forming a 45° angle. In other words, in one embodiment of the present invention, since the magnetism is excellent in the entire direction of the steel plate, the magnetic flux density (B50) is excellent even in the 45° direction, which is conventionally known to have the lowest magnetic flux density. 45° ) comes out high. Therefore, according to one embodiment of the present invention, regarding the average value of magnetic flux density in the rolling direction and the direction perpendicular to the electrical steel sheet manufactured by the conventional method, the magnetic flux density (B50) including up to the 45° direction 45° ) becomes higher than the ratio of the average value.

[0121] Equation 3 is the magnetic flux density (B50) of the steel plate measured in a direction forming a 45° angle. 45°) is the value obtained by dividing the average value of the magnetic flux density in the rolling direction (L) of the steel plate and the direction perpendicular thereto (C); since the magnetic flux density is high in the entire direction of the steel plate, the magnetic flux density in the direction forming a 45° angle of the steel plate manufactured by the conventional method (B50 45° It means that it is higher than ). With the existing method, {100} <001> exact Cube collection and {110} <001> By developing a Goss texture, the magnetic flux density increases only in the rolling direction of the steel sheet and in the direction perpendicular thereto; however, since the magnetic flux density in the 45° direction relative to the rolling direction is very inferior, the magnetic properties cannot be evaluated as excellent across the entire direction of the steel sheet. As in one embodiment of the present invention, in a steel sheet <100> It is possible to manufacture non-oriented electrical steel sheets for drive motors that have excellent magnetic flux density in the rolling direction and perpendicular direction as well as in the 45° direction to the rolling direction by controlling the dew point during high-temperature hot rolling and coiling, low-temperature batch hot-rolled sheet annealing, and warm-cold rolling and cold-rolled sheet annealing, with an optimal resistivity-enhancing alloy composition to increase the area fraction of the / ND crystal grains.

[0122] More specifically, the value of Equation 1 may be 1.67 to 1.75. The value of Equation 2 may be 1.64 to 1.73. The value of Equation 3 may be 0.96 to 1.00.

[0123]

[0124] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention comprises: a step of manufacturing a hot-rolled steel sheet by hot-rolling a slab; a hot-rolled sheet annealing step of annealing the hot-rolled steel sheet; a step of manufacturing a cold-rolled sheet by cold-rolling the annealed hot-rolled steel sheet; and a cold-rolled sheet annealing step of annealing the cold-rolled sheet.

[0125] Below, each step is explained in detail.

[0126] First, the slab is hot-rolled.

[0127] As the alloy composition of the slab has been explained in the aforementioned section on the alloy composition of non-oriented electrical steel sheets, a redundant explanation is omitted. Since the alloy composition does not substantially change during the manufacturing process of non-oriented electrical steel sheets, the alloy composition of the non-oriented electrical steel sheets and the slab is substantially the same.

[0128] Specifically, the slab contains Si: 1.5 to 5.0%, Al: 0.1 to 3.0%, Mn: 0.1 to 3.0% by weight, and the remainder is Fe and unavoidable impurities.

[0129] As other additional elements have been explained in the alloy composition of non-oriented electrical steel sheets, redundant explanations are omitted.

[0130] The slab can be heated before hot rolling. The heating temperature of the slab is not limited, but the slab can be heated to 1000°C to 1250°C. If the heating temperature of the slab is too high, precipitates such as AlN and MnS present in the slab may be re-dissolved and then finely precipitated during hot rolling and annealing, which can suppress grain growth and reduce magnetism.

[0131] Next, a hot-rolled plate is manufactured by hot-rolling a slab. The thickness of the hot-rolled plate may be 1.0 to 2.5 mm. In one embodiment of the present invention, since batch annealing is performed on the hot-rolled plate before cold rolling, electrical steel sheets can be manufactured without increasing process load even if the thickness of the hot-rolled plate is relatively thin. More specifically, the thickness of the hot-rolled plate may be 1.5 to 2.3 mm.

[0132] The steps for manufacturing a hot-rolled plate may include a step of finish rolling at a temperature of 850°C or higher; a step of water cooling after a time of 0.1 seconds or more has elapsed since finish rolling; and a step of coiling at a temperature of 600 to 800°C. A step of rough rolling before the finish rolling step may also be included. That is, after cooling the hot-rolled steel plate to 600 to 800°C, it is annealed in the hot-rolled plate annealing step.

[0133] If the finishing rolling temperature of hot rolling is too low, the rolling load increases, leading to reduced hot rolling workability. Furthermore, a significant amount of deformation remains in the hot-rolled steel sheet, which causes an increase in the rolling load during the subsequent pre-cold rolling process. In addition, from the deformation during intermediate annealing <111> / ND Recrystallization of the grains is promoted, resulting in lower magnetic flux density. Therefore, the higher the hot rolling finish rolling temperature, the better, and more specifically, it is desirable to perform finish rolling at a temperature of 860 to 1000℃.

[0134] After finish rolling, cooling is performed for coiling. However, if water cooling is carried out immediately after finish rolling (i.e., within less than 0.1 seconds), the rapid cooling of the steel sheet can cause deformation and residual stress, making coiling difficult. Furthermore, from a microstructural perspective, the deformation stress from finish rolling remains unreleased, leading to increased rolling load during the subsequent cold rolling stage and... <111> / ND orientation may lead to recrystallization. Therefore, maintaining the position for at least 0.1 seconds immediately after hot rolling finish rolling allows the hot rolling deformation structure to recover and recrystallize, thereby reducing the rolling load during subsequent pre-cold rolling, and <111> / ND orientation suppresses the formation of recrystallized grains. More specifically, water cooling can be performed after 0.3 to 3.0 seconds.

[0135] If the temperature during the coiling stage is managed too low, the recovery and recrystallization of the hot-rolled deformed structure do not occur effectively. Additionally, the cooling load increases to rapidly cool the steel sheet to a low temperature, which may cause difficulties in coiling the supercooled coil. Conversely, if the temperature is too high, recovery and recrystallization may be promoted, but additional oxidation by atmospheric oxygen may occur during coiling, leading to the formation of a thicker scale and problems with intergranular oxidation. Intergranular oxidation of the hot-rolled sheet promotes intergranular corrosion during the subsequent pickling process, increasing the likelihood of surface streak defects and causing severe wear on the rolling rolls. Therefore, it is preferable to perform the coiling at a temperature of 600 to 800°C, and more specifically, coiling can be performed at 600 to 750°C.

[0136] Next, in the hot-rolled sheet annealing step, the hot-rolled steel sheet is annealed. It is annealed for 1 to 40 hours at a cracking temperature of 650 to 850°C. If the annealing temperature of the hot-rolled sheet is too low, the recrystallized structure is not formed or grows finely, resulting in a small increase in magnetic flux density; if the annealing temperature is too high, the grain size of the hot-rolled sheet grows coarsely, increasing the likelihood of sheet fracture, and furthermore, excessive growth of the surface oxide layer due to high-temperature annealing may worsen pickling and rolling properties. More specifically, the temperature range may be 700 to 850°C. If the annealing time is too short, the variation in grain size in the width and length directions of the coil increases, which may lead to a problem of inferior magnetic properties. If the annealing time is too long, abnormal grain growth occurs, which is unfavorable to magnetism {111} <112> A problem may occur where the microstructure develops coarsely, resulting in poor iron loss. More specifically, the annealing time can be 20 to 35 hours.

[0137] In the hot-rolled steel sheet manufacturing stage, the hot-rolled steel sheet is wound into a coil, and the wound coil can be batch annealed in the hot-rolled steel sheet annealing stage.

[0138] Batch annealing of hot-rolled sheets is an efficient annealing method in which hot-rolled coils wound immediately after hot rolling are loaded directly into a batch annealing furnace for heat treatment. In other words, annealing hot-rolled sheets in the shape of coils is called batch annealing. The same effect can be achieved by undergoing a cooling process and then loading them into the batch annealing furnace for heat treatment. In this case, when batch annealing cooled coils, they can be annealed by heating at a heating rate of 15℃ / hr or more.

[0139] Batch-annealed steel sheets can be pickled before cold rolling.

[0140] Next, the step of manufacturing cold-rolled sheets involves cold-rolling annealed hot-rolled steel sheets. To improve rolling productivity, cold rolling can be performed in a PCM (Pickling & Cold Rolling Mill) that includes a pickling process or a TCM (Tandem Cold Rolling Mill) that performs only cold rolling, or it can be carried out in a Reverse Mill.

[0141] It is also possible to cold roll to an intermediate thickness rather than the final product thickness, perform intermediate annealing, and then cold roll to the final product thickness.

[0142] However, continuous annealing is more efficient than batch annealing for intermediate annealing, and to minimize material variation in the width and length directions and prevent problems such as surface oxidation, annealing can be performed in an inert gas atmosphere such as nitrogen or a reducing gas atmosphere containing hydrogen.

[0143] The step of manufacturing cold-rolled sheets can be carried out at a temperature of 100 to 400°C. Generally, during cold rolling, the temperature of the steel sheet rises due to friction between the steel sheet and the rolling rolls, but the temperature of the steel sheet can be increased through induction heating or electric heating. If the temperature is too low, the rolling load increases significantly, and it is advantageous for magnetism <100> / ND less favorable to magnetism than the texture of the orientation <111> This promotes the formation of a texture with / ND orientation. In addition, the steel sheet may slide between the rolling rolls instead of being rolled, which can cause problems such as twisting. If the temperature is too high, an oxide layer may form on the surface of the steel sheet due to Si and Al oxidation, and the magnetic properties may deteriorate after final annealing, and problems such as the rolling oil igniting during operation may occur. More specifically, cold rolling can be performed at a temperature of 150 to 350°C.

[0144] When cold rolling using a two-rolling method that includes intermediate annealing, the intermediate annealing temperature can be performed within a temperature range of 600 to 1100°C. If the annealing temperature is too low, the grain size becomes finer and the grain boundaries increase, causing the grain boundaries at the time of final cold rolling. <111> / ND orientation recrystallization nuclei increase, eventually leading to a decrease in magnetic flux density. Conversely, if the annealing temperature is too high, the number of grains increases significantly, which may result in increased plate fracture due to cracking at grain boundaries during final cold rolling. Preferably, annealing can be performed specifically at 750 to 1050°C.

[0145] During cold rolling, a reduction rate of 40 to 85% can be performed. If the reduction rate is too low, the deformation energy accumulated in the rolled steel sheet is small, making it difficult to recrystallize during the subsequent annealing process. As a result, the rolled structure remains, which may cause problems in improving magnetic flux density and iron loss. Conversely, if the reduction rate is too high, during the subsequent annealing process <111> / ND orientation. Recrystallization of the grains is promoted and the grains become finer, which may result in problems such as reduced magnetic flux density and increased iron loss. More specifically, the reduction ratio may be 60 to 75%. For the cold rolling step, a tandem cold rolling mill that continuously cold-rolls the steel sheet using multiple rolling stands or a reverse rolling mill that discontinuously cold-rolls using 12 or more rolling rolls may be used. After rolling, the thickness of the final cold-rolled sheet may be 0.10 mm to 0.35 mm.

[0146] In the cold rolling stage, the diameter of the work roll may be 70 to 400 mm. If the work roll diameter is too small, bending may occur during rolling, which can lead to problems with the plate shape deteriorating. If the work roll diameter is too large, it may be problematic in that the rolling load increases significantly when rolling to a thickness of 0.25 mm or less. More specifically, the diameter of the work roll may be 80 to 350 mm. More specifically, it may be 300 to 340 mm.

[0147] Next, the cold-rolled sheet is annealed. In the cold-rolled sheet annealing stage, the difference between the dew point temperature (DPH) in the heating stage from 300 to 800°C and the dew point temperature (DPS) in the cracking stage may be 20°C or more.

[0148] During the heating stage, the dew point temperature can be managed to -10°C or lower. In the heating section, a thick oxide layer forms on the surface of the steel plate, which is highly likely to impair the magnetism of the final product. In the cracking section, since the steel plate is heat-treated at a higher temperature than in the heating section, the dew point of the atmosphere gas has a significant impact on magnetism and the surface; therefore, it is necessary to manage the dew point at a low level. More specifically, during the heating stage, the dew point temperature can be managed to be between -30°C and -50°C.

[0149] In addition, it is very important to control the difference in the atmosphere gas dew point (ΔDP = DPH-DPS) between the heating section and the cracking section to be 20°C or more. More specifically, the difference in the atmosphere gas dew point (ΔDP = DPH-DPS) can be controlled to be between 25°C and 50°C.

[0150] The cracking stage refers to the period from when the instantaneous temperature change rate of the steel plate is 0.1℃ / sec or less to when the instantaneous temperature change rate of the steel plate is -0.1℃ / sec or more.

[0151] The cracking temperature can be 800 to 1050°C. If the annealing temperature is too low <111> / ND Recrystallization of the grains is promoted, and the grains become finer, making it impossible to secure excellent magnetic flux density characteristics. If the annealing temperature is too high, the grains grow coarsely, increasing iron loss, and an oxide layer or nitride layer may form on the surface of the steel sheet from the annealing atmosphere gas, which also causes an increase in iron loss. More specifically, annealing can be performed at 870 to 1020℃.

[0152] The dew point temperature (DPS) at the cracking stage may be -30°C to -80°C. More specifically, it may be -50°C to -70°C.

[0153] During the annealing process of the cold-rolled sheet, all (i.e., more than 99%) of the processed structure formed during the cold rolling stage can be recrystallized.

[0154] After annealing the cold-rolled sheet, an insulating film can be formed. The insulating film can be treated with organic, inorganic, or organic-inorganic composite films, and it is also possible to treat it with other insulating coating materials.

[0155]

[0156] The present invention will be explained in more detail below through examples. However, these examples are merely for illustrating the invention and the invention is not limited thereto.

[0157]

[0158] Examples

[0159] A slab containing the remainder of Fe and other impurities as shown in Table 1 below was prepared. This was heated to 1150°C and hot-rolled at a finishing temperature of 900°C to produce a hot-rolled plate with a thickness of 2.0 mm. The hot-rolled plate was annealed under the conditions listed in Table 1 below and cold-rolled under the conditions listed in Table 1 below to produce a cold-rolled plate with a thickness of 0.25 mm. Subsequently, the cold-rolled plate was annealed for 100 seconds under the conditions listed in Table 1.

[0160] The main characteristic values ​​for each specimen that underwent the manufacturing process are summarized in Table 1.

[0161] {100} <011> Random intensity ratio of orientation and {411} <148> The random intensity ratio of each orientation was calculated from the orientation distribution function (ODF) analyzed by EBSD measurement and summarized in Table 2.

[0162] <111> / ND, <110> / ND and <100> The / ND grain fraction was measured using a TSL EBSD measuring device mounted on a JEOL Scanning Electron Microscope (model name JSM-7200F) on a cross-section including the rolling direction of the steel sheet. The error angle was set to 15°, and measurements were taken using the crystal orientation analysis program (OIM) of the TSL EBSD. After removing the surface up to 1 / 4 thickness of the steel sheet from a cross-section parallel to the rolling plane (ND plane), the crystal orientation of the grains was analyzed on the chemically polished surface through electron backscatter diffraction (EBSD) measurements. The measurement interval was 2 µm, and the total measurement area was 5000 µm × 5000 µm.

[0163] For each specimen, five specimens measuring 60 mm in width × 60 mm in length were cut, and the magnetic flux density was measured using a single sheet tester in the rolling direction, the direction perpendicular to the rolling direction, and at a 45° angle in the rolling direction, and is shown in Table 3. In this case, B50 refers to the magnetic flux density of the steel plate induced in a magnetic field of 5000 A / m.

[0164] Classification SiAlMn Hot Rolled Annealing Temperature (°C) Hot Rolled Annealing Time (Hour) Cold Rolled Steel Sheet Temperature (°C) Work Roll Diameter (mm) Heating Section Dew Point Temperature (°C) Cracking Section Dew Point Temperature (°C) Cold Rolled Sheet Annealing Cracks Temperature (°C) 13.01.50.480030200340-30-5295023.01.20.480030200340-30-5295033.01.00.482525250340-30-52100043.50.70.482525250340-30-52100053.50.70.482525300340-40-6595063.50.70.485020300340-40-6595073.80.70.485020350340-40-659 5084.00.50.482520350340-40-6590094.20.50.380028150340-40-65900103.50.71.578035150340-40-65900111.80.30.765038120340-20-42950124.60.30.76503812080-20-42900132.50.20.77003812080-20-42950142.51.70.47503815080-20-4295015 2.50.30.27503815080-20-42950162.50.32.17503815080-20-42950173.50.70.460040200340-40-65950183.50.70.48801.5200340-40-65950193.50.70.483042200340-40-65950203.50.70.48300.5200340-40-65950214.00.70.483030120290-40-65950 224.00.70.483030350290-40-65950234.00.70.48303025075-40-65950244.00.70.483030250380-40-65950253.50.70.483030150340-5-50950263.50.70.483030150340-30-40950274.00.70.483030250340-40-65825284.00.70.483030250340-40-651040

[0165] Category{100} <011> Random intensity ratio{411} <148> Random intensity ratio <111> / ND fraction (area %) <100> / ND / <110> / ND <100> / ND Fraction (Area %) 13.13.719 1.5212 2.83.018 2.1223 3.52.919 1.924 43.22.516 1.8225 2.53.722 3.2256 2.73.419 4.5347 2.73.3212.8288 2.62.815 3.3319 3.33.4174.138 102.83.522 1.119112.13.5240.712125.53.822 1.222132.03.3240.813143.23.3231.119 152.23.5230.913162.13.9240.715170.83.8261.19182.24.5312.512192.44.1251.18200.74.2290.413213.73.2201.219223.43.8251.421232.93.4221.320242.43.7231.525251.93.4221.111261.53.5290.810275.83.8252.320282.13.9202.415

[0166] Classification Formula 1 Formula 2 Formula 3 11.67 1.65 0.96 Invention Example 2 1.68 1.65 0.97 Invention Example 3 1.68 1.65 0.97 Invention Example 4 1.69 1.66 0.96 Invention Example 5 1.68 1.65 0.96 Invention Example 6 1.70 1.66 0.98 Invention Example 7 1.69 1.66 0.97 Invention Example 8 1.68 1.65 0.97 Invention Example 9 1.71 1.67 0.96 Invention Example 10 1.67 1.64 0.97 Invention Example 11 1.65 1.63 0.95 Invention Example 12 1.65 1.64 0.96 Invention Example 13 1.65 1.63 0.95 Invention Example 14 1.65 1.63 0.96 Invention Example 15 1. 651.630.95 Invention Example 16 1.651.630.95 Invention Example 17 1.641.610.94 Comparative Example 18 1.641.630.95 Comparative Example 19 1.631.610.95 Comparative Example 20 1.621.590.93 Comparative Example 21 1.671.630.95 Invention Example 22 1.671.640.96 Invention Example 23 1.681.640.96 Invention Example 24 1.671.640.96 Invention Example 25 1.641.610.94 Comparative Example 26 1.641.600.94 Comparative Example 27 1.651.630.95 Invention Example 28 1.651.640.95 Invention Example

[0167] As shown in Tables 1 to 3, when the steel composition is appropriately controlled and process conditions are appropriately controlled and a specific texture is developed, it can be confirmed that the magnetic flux density is excellent in all directions.

[0168] On the other hand, if process conditions are not properly controlled and a specific texture is not developed, it can be confirmed that the magnetic flux density is inferior.

[0169]

[0170] The present invention is not limited to the embodiments described above but can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without altering the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. In weight%, it comprises Si: 1.5 to 5.0%, Al: 0.1 to 3.0%, Mn: 0.1 to 3.0%, and the remainder being Fe and unavoidable impurities, and {100} at the point 1 / 4 of the total thickness in the thickness direction from the surface <011> The random intensity ratio of the orientation grains is 2 or greater and {411} <148> Non-oriented electrical steel sheet with a random strength ratio of orientation grains of 4 or less.

2. In Paragraph 1, <111> The area fraction of grains parallel to the ND direction of the steel sheet within 15° is 25% or less, and <110> for the area fraction of grains parallel to the ND direction of the steel sheet within 15° <100> A non-oriented electrical steel sheet having a ratio of the area fraction of grains parallel to the ND direction of the steel sheet within 15° to 0.5 to 5.

3. In Paragraph 1, <100> Non-oriented electrical steel sheet having an area fraction of grains parallel to the ND direction within 15° of the sheet at 10% or more.

4. In Paragraph 1, A non-oriented electrical steel sheet further comprising one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

5. In Paragraph 1, A non-oriented electrical steel sheet further comprising 0.005 to 0.200 weight% of one or more of Sn, Sb, Bi, Pb, Ge, and As, either individually or in their combined amount.

6. In Paragraph 1, A non-oriented electrical steel sheet further comprising one or more of Cu: 0.2 wt% or less, Cr: 0.5 wt% or less, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

7. In Paragraph 1, A non-oriented electrical steel sheet further comprising one or more of Mo: 0.03 wt% or less, B: 0.01 wt% or less, V: 0.01 wt% or less, Ca: 0.01 wt% or less, Nb: 0.01 wt% or less, Zr: 0.01 wt% or less, Te: 0.01 wt% or less, and Mg: 0.01 wt% or less.

8. A step of manufacturing a hot-rolled steel sheet by hot-rolling a slab containing, by weight%, Si: 1.5 to 5.0%, Al: 0.1 to 3.0%, Mn: 0.1 to 3.0%, and the remainder being Fe and unavoidable impurities; A hot-rolled steel plate annealing step for annealing the above hot-rolled steel plate; A step of manufacturing a cold-rolled sheet by cold-rolling an annealed hot-rolled steel sheet and Cold-rolled plate annealing step for annealing the above-mentioned cold-rolled plate; Includes, In the above hot-rolled plate annealing step, the plate is annealed at a cracking temperature of 650 to 850°C for 1 to 40 hours, and In the heating step from 300 to 800°C during the above cold-rolled sheet annealing step, the dew point temperature (DPH) is -10°C or lower, and A method for manufacturing non-oriented electrical steel sheets in which the difference between the dew point temperature (DPH) in the heating stage and the dew point temperature (DPS) in the cracking stage is 20°C or more.

9. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further comprises one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

10. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further comprises 0.005 to 0.200 weight% of one or more of Sn, Sb, Bi, Pb, Ge, and As, respectively or in their combined amount.

11. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further comprises one or more of Cu: 0.2 wt% or less, Cr: 0.5 wt% or less, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

12. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further comprises one or more of Mo: 0.03 wt% or less, B: 0.01 wt% or less, V: 0.01 wt% or less, Ca: 0.01 wt% or less, Nb: 0.01 wt% or less, Zr: 0.01 wt% or less, Te: 0.01 wt% or less, and Mg: 0.01 wt% or less.

13. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet by winding a hot-rolled steel sheet into a coil in the above-mentioned hot-rolled steel sheet manufacturing step and batch annealing the wound coil in the hot-rolled steel sheet annealing step.

14. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet by cooling the hot-rolled steel sheet to 600 to 800°C in the above hot-rolled steel sheet manufacturing step, and then annealing it in the hot-rolled sheet annealing step.

15. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet in which the temperature of the steel sheet during the above cold rolling step is 100 to 400℃.

16. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet in which the diameter of the work roll in the above cold rolling step is 70 to 400 mm.

17. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet in which the cracking temperature during the annealing step of the cold-rolled sheet is 800 to 1050℃.