Non-oriented electrical steel sheet and manufacturing method therefor

Abstract

A non-oriented electrical steel sheet according to one embodiment of the present invention comprises, by wt%, 1.5-5.0 wt% of Si, 0.1-2.5 wt% of Al, 0.1-2.5 wt% of Mn, and the balance of Fe and inevitable impurities, and has a ratio of an average grain size of crystal grains having an angle of 5° or less with respect to {001}<110> to an average grain size of crystal grains having an angle of 5° or less with respect to {110}<110> is 1.2 or greater.

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 in which the thermal shrinkage rate of the steel sheet is appropriately controlled and a method for manufacturing the same.

[0002] There is a growing demand for improved efficiency in motors and generators, which are energy conversion devices that convert mechanical energy into electrical energy. Since non-oriented electrical steel is used as a core material in rotating machinery such as motors and generators, as well as in stationary machinery such as small transformers, and significantly impacts efficiency, the demand for increased efficiency in motors and generators is leading to a demand for improved characteristics of non-oriented electrical steel.

[0003] The representative magnetic properties of non-oriented electrical steel sheets are iron loss and magnetic flux density. Lower iron loss reduces the iron loss lost during the magnetization process of the iron core, thereby improving efficiency. Higher magnetic flux density allows for the induction of a larger magnetic field with the same amount of energy, and requires less current to achieve the same magnetic flux density, thus improving energy efficiency.

[0004] Factors affecting iron loss and magnetic flux density include the texture of the material and residual stress. Additionally, the tension applied to the material during annealing acts on recrystallization, affecting the development of the texture and the level of residual stress. At this time, some of the tension applied to the material is also attributed to thermal shrinkage that occurs during the cooling process of the leading edge of the material after it exits the annealing furnace.

[0005] Ultimately, to improve the iron loss and magnetic flux density of non-oriented electrical steel sheets, tension control considering the thermal shrinkage rate of the material is very important.

[0006] 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 in which the thermal shrinkage rate of the steel sheet is appropriately controlled, and a method for manufacturing the non-oriented electrical steel sheet.

[0007] 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 2.5%, Mn: 0.1 to 2.5%, the remainder being Fe and unavoidable impurities, and {110} <110> {001} for the average grain size of crystal grains having an angle within 5° from <110> The ratio of the average grain size of crystal grains having an angle within 5° from is 1.2 or higher.

[0008] am.

[0009] A non-oriented electrical steel sheet according to one embodiment of the present invention, when heat-treated at a temperature of 900°C for 10 seconds and then cooled at a rate of 1°C / s while measuring the thermal shrinkage rate in the rolling direction, was 1.40 × 10 in the 880 to 750°C range. -5 mm / mm·K to 1.85 × 10⁻⁶ -5 mm / mm·K and; 1.35 × 10⁻⁶ in the range of 700 to 550 ℃ -5 mm / mm·K to 1.65 × 10⁻⁶ -5 It can be mm / mm·K.

[0010] {111} <112> {001} for the KAM value of grains having an angle within 5° from <110> The ratio of KAM values ​​of grains having an angle within 5° from may be 0.9 or less.

[0011] 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.

[0012] 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.

[0013] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

[0014] 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: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 wt% or less.

[0015] 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 comprising, in weight%, Si: 1.5 to 5.0%, Al: 0.1 to 2.5%, Mn: 0.1 to 2.5%, and the remainder being Fe and unavoidable impurities; a step of manufacturing a cold-rolled sheet by cold-rolling the hot-rolled steel sheet; and a cold-rolled sheet annealing step of annealing the cold-rolled sheet.

[0016] During the cold-rolled sheet annealing stage, the following Equation 1 is satisfied at the exit side of the annealing furnace.

[0017] [Equation 1]

[0018] 0.15 ≤ (TR max - TR min ) / TR ave ≤ 0.45

[0019] (TR in Equation 1 ave , TR max and TR minAverage tension, maximum tension, and minimum tension (kgf / mm²) in a 100m section of silver steel plate 2 It represents ).

[0020] 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.

[0021] 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.

[0022] The slab may further include one or more of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

[0023] The slab may further include one or more of Mo: 0.03 wt% or less, B: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 wt% or less.

[0024] A non-oriented electrical steel sheet according to one embodiment of the present invention has excellent iron loss and magnetic flux density simultaneously.

[0025] 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 motor cores.

[0026] 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.

[0027] 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.

[0028] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0029] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0030] 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.

[0031] 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.

[0032] 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.

[0033]

[0034] A non-oriented electrical steel sheet according to one embodiment of the present invention comprises, in weight%, Si: 1.5 to 5.0%, Al: 0.1 to 2.5%, Mn: 0.1 to 2.5%, and the remainder being Fe and unavoidable impurities.

[0035] Below, we will explain the reason for limiting the composition of non-oriented electrical steel sheets.

[0036]

[0037] Si: 1.5 to 5.0 wt%

[0038] Silicon (Si) is a major element added to increase the resistivity of steel to reduce eddy current losses among iron losses, and is added to secure low iron loss characteristics, particularly in the high-frequency region. If too little Si is added, the effect of improving iron loss may be insufficient. If too much Si is added, the magnetic flux density decreases significantly and machinability may decline. More specifically, it may contain 2.0 to 4.5 weight%. More specifically, it may contain 3.0 to 4.0 weight%.

[0039]

[0040] Al: 0.1 to 2.5 wt%

[0041] Aluminum (Al) is an element added because it plays an important role in reducing iron loss by increasing resistivity together with Si, and also reduces magnetic anisotropy, thereby reducing magnetic deviation in the rolling direction and the rolling perpendicular direction. However, if the amount added is small, the effect of reducing iron loss is not significant, and if the amount added is too large, the magnetic flux density is significantly inferior and workability may also be inferior. More specifically, it may be included in an amount of 1.0 to 2.3 weight%. More specifically, it may be included in an amount of 1.2 to 2.0 weight%.

[0042]

[0043] Mn: 0.1 to 2.5 wt%

[0044] Manganese (Mn), along with Si and Al, is an element that increases resistivity and lowers iron loss. However, if the amount added is too small, it forms fine sulfides, which may be disadvantageous for texture control during subsequent annealing heat treatment after hot rolling. If the amount added is excessive, not only is the magnetic flux density significantly reduced, but the risk of formation according to B2 and DO3 rules may also increase in localized areas of the hot-rolled steel sheet. More specifically, it may be included in an amount of 0.2 to 2.0 weight%. More specifically, it may be included in an amount of 0.3 to 1.7 weight%.

[0045]

[0046] 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.

[0047] P: 0.1 wt% or less

[0048] Phosphorus (P) has the effect of improving the texture of steel as a grain boundary and surface segregation element. However, if too much phosphorus is added, it inhibits grain growth, thereby reducing iron loss, and reduces rolling performance due to grain boundary segregation, which may also reduce productivity. More specifically, it may further contain 0.005 to 0.050 weight% of P.

[0049] C: 0.005 wt% or less

[0050] Carbon (C) combines with Ti, Nb, etc. to form carbides, thereby degrading magnetism, and when used after processing from the final product into an electrical product, iron loss increases due to magnetic aging, which reduces the efficiency of the electrical device; therefore, it can be limited to 0.005 weight% or less. More specifically, C may be included in an amount of 0.0001 to 0.003 weight%.

[0051] S: 0.005 wt% or less

[0052] Sulfur (S) is an element that forms sulfides such as MnS, CuS, and (Cu,Mn)S, which are detrimental to magnetic properties, so it is desirable to add it in the lowest possible amount. If too much sulfur is added, the magnetic properties may deteriorate due to an increase in sulfides. More specifically, S may be included in an amount of 0.0005 to 0.0040 weight%.

[0053] Ti: 0.005 wt% or less

[0054] Titanium (Ti) forms fine carbides and nitrides by bonding with C and N, thereby inhibiting grain growth and degrading magnetic flux density; as more is added, the texture also degrades due to the increased carbides and nitrides, which can lead to poor magnetism. More specifically, it may contain 0.0001 to 0.005 weight% of Ti. More specifically, it may contain 0.0001 to 0.003 weight% of Ti.

[0055] N: 0.005 wt% or less

[0056] Nitrogen (N) is an element harmful to magnetism, as it forms nitrides by strongly bonding with Al, Ti, Nb, etc., thereby inhibiting grain growth, so it may be included in small amounts. More specifically, N may be included in an amount of 0.0001 to 0.0030 weight%.

[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) are elements that improve the texture and may be added for further improvement of magnetism. 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 further improve magnetic flux density. If they are added appropriately, the aforementioned effects can be additionally obtained; however, if they are included in excessive amounts, a large amount of segregation occurs, which inhibits grain growth and may result in inferior magnetic flux density and iron loss. More specifically, one or more of Bi, Pb, Ge, and As may be included in an amount of 0.200 wt% or less, either individually or in their total amount. More specifically, one or more of Bi, Pb, Ge, and As may be included in an amount of 0.0001 to 0.200 wt%, either individually or in their total amount. More specifically, one or more of Bi, Pb, Ge, and As may be included in an amount of 0.001 to 0.100 wt%, either individually or in their total amount.

[0062]

[0063] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

[0064] Cu: 0.005 to 0.200 wt%

[0065] Copper (Cu) may be added for reasons such as improving magnetism, but it may react with impurity elements to form fine sulfides, carbides, and nitrides, which may have a harmful effect on magnetism. More specifically, it may contain 0.01 to 0.10 weight% of Cu.

[0066] Cr: 0.01 to 0.50 wt%

[0067] Chromium (Cr) plays a role in improving iron loss by increasing resistivity. If too little Cr is added, the effect of increasing resistivity may not be sufficient. If too much Cr is included, magnetic flux density may decrease. More specifically, 0.050 to 0.20 weight% of Cr may be included.

[0068] Ni: 0.05 wt% or less

[0069] Nickel (Ni) may be added for reasons such as improving magnetism, but it may react with impurity elements to form fine sulfides, carbides, and nitrides, which may have a harmful effect on magnetism. More specifically, it may contain 0.001 to 0.03 weight% 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 the steel sheet, but it increases high-temperature strength, which can cause the coil shape to be defective after hot rolling. More specifically, Co may be included in an amount of 0.001 to 0.02 weight%.

[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, B: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 wt% or less.

[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: 0.0050 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 0.0030 weight%.

[0080] V: 0.0050 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 0.0050 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 0.0050 wt%. More specifically, V may be included in 0.0003 to 0.0030 wt%.

[0082] Ca: 0.0050 wt% or less

[0083] Calcium (Ca) has a very strong tendency to form precipitates within the steel and degrades iron loss by forming fine sulfides inside the base material, thereby inhibiting grain growth and domain wall movement.

[0084] Nb: 0.0050 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 0.0050 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 0.0050 wt% of Nb. More specifically, it may contain 0.0003 to 0.0030 wt% of Nb.

[0086] Zr: 0.0050 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 0.005 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 0.0050 weight%. More specifically, it may be included in an amount of 0.0005 to 0.0030 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: 0.0050 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 0.0050 wt% or less. The lower limit is not specifically limited, but it may be 0.0001 wt% due to steelmaking costs. That is, Mg may be included in an amount of 0.0001 to 0.0050 wt%. More specifically, it may be included in an amount of 0.0005 to 0.0030 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] A non-oriented electrical steel sheet according to one embodiment of the present invention satisfies the following Equation 1. When the thermal shrinkage rate in the rolling direction is measured while cooling at 1°C / s after heat treatment at a temperature of 900°C for 10 seconds, it is 1.40 × 10⁻⁶ in the range of 880 to 750°C. -5 mm / mm·K to 1.85 × 10⁻⁶ -5 mm / mm·K and; 1.35 × 10⁻⁶ in the range of 700 to 550 ℃ -5 mm / mm·K to 1.65 × 10⁻⁶ -5 It is mm / mm·K.

[0096] The thermal shrinkage rate in the range of 880 to 750℃ is {110} <110> {001} for the average grain size of crystal grains having an angle within 5° from <110> The ratio of the average grain size of crystal grains having an angle within 5° from ({001}) <110> / {110} <110> It is related to ). In one embodiment of the present invention, it was confirmed that a material with a low average particle size ratio has a high thermal shrinkage rate. More specifically, in the range of 880 to 750 ℃, the thermal shrinkage rate is 1.42 × 10 -5 mm / mm·K to 1.85 × 10⁻⁶ -5 It can be mm / mm·K.

[0097] The thermal shrinkage rate in the range of 700 to 550 ℃ is {111} <112> {001} for the KAM value of grains having an angle within 5° from <110> It is related to the ratio of KAM values ​​of grains having an angle within 5° from. In one embodiment of the present invention, it was confirmed that a material with a high ratio of KAM values ​​has a high thermal shrinkage rate. More specifically, in the range of 700 to 550 ℃, the thermal shrinkage rate is 1.37 × 10 -5 mm / mm·K to 1.64 × 10⁻⁶ -5 It can be mm / mm·K.

[0098] A non-oriented electrical steel sheet according to one embodiment of the present invention is {110} <110> {001} for the average grain size of crystal grains having an angle within 5° from <110> The ratio of the average grain size of crystal grains having an angle within 5° from ({001}) <110> / {110} <110> ) may be 1.20 or higher. If this ratio is low, {001} <110> This means that the average grain size of crystal grains having an angle within 5° from is formed to be relatively small. Typically, in non-oriented electrical steel sheets, {001} in terms of iron loss and magnetic contribution in both orientations <110> This {110} <110> Since it is known to be higher, the larger the corresponding average particle size ratio, the better. More specifically, the ratio of average particle size ({001} <110> / {110} <110> ) can be 1.20 to 1.70.

[0099]

[0100] The determination of the corresponding orientation of each grain can be obtained by measuring the cross-section of the steel plate using Electron Backscatter Diffraction (EBSD) and setting the grain tolerance angle to 5°. The grain diameter is determined by assuming a virtual circle with the same area as the grain and calculating the diameter of that circle. The cross-section can be parallel to the rolled surface of the steel plate. To reduce errors caused by the thickness direction, the same number of specimens can be measured at 1 / 8, 1 / 4, and 1 / 2 points of the steel plate thickness, and the average can be calculated. The average in the average grain diameter refers to the average of the number of grains.

[0101] Specifically, {110} <110> The average grain size of crystal grains having an angle within 5° from may be 80 to 115 μm. Also, {001} <110> The average grain size of crystal grains having an angle within 5° from may be 120 to 150 μm.

[0102] A non-oriented electrical steel sheet according to one embodiment of the present invention is {111} <112> {001} for the KAM (Kernel Average Misorientation) value of grains having an angle within 5° from <110> The ratio of KAM (Kernel Average Misorientation) values ​​of grains having an angle within 5° from ({001}) <110> / {111} <112> ) may be 0.90 or less. Typically, KAM is associated with the residual stress of the material. That is, it is known that if KAM is high, the residual stress of the material is high, and if KAM is low, the residual stress of the material is low.

[0103] If the ratio of KAM values ​​is too large, relatively {001} <110> This means that the KAM value of grains having an angle within 5° from is large. Typically, in non-oriented electrical steel sheets, {001} in terms of iron loss and magnetic contribution in two orientations <110> This {110} <110> It is known to be higher than {110} in the present invention <110> {001} relative to residual stress <110> It was confirmed that controlling the residual stress to be small is advantageous in terms of iron loss and securing magnetism. More specifically, the ratio of the KAM value can be between 0.60 and 0.89. The KAM value can be obtained by measuring the cross-section of the steel plate using Electron Backscatter Diffraction (EBSD). The cross-section can be a cross-section parallel to the rolled surface of the steel plate. To reduce errors caused by the thickness direction, the same number of specimens can be measured at 1 / 8, 1 / 4, and 1 / 2 points of the steel plate thickness and the average can be obtained. The average at the average grain size refers to the average of the number of crystal grains.

[0104] Specifically, {001} <110> The KAM value of grains having an angle within 5° from can be 0.35 to 0.40°. Also, {111} <112> The KAM value of a grain having an angle within 5° from can be 0.43 to 0.65°.

[0105]

[0106] A non-oriented electrical steel sheet according to one embodiment of the present invention exhibits excellent magnetic flux density and iron loss simultaneously. Specifically, the non-oriented electrical steel sheet according to one embodiment of the present invention has an iron loss (W 10 / 400 ) is 16.0 W / Kg or less, and magnetic flux density (B 50 ) can be 1.60T or more.

[0107] B 50 represents the magnetic flux density induced in a magnetic field of 5000 A / m. W 10 / 400represents the iron loss when a magnetic flux density of 1.0T is induced at a frequency of 400Hz.

[0108] In one embodiment of the present invention, B 50 and W 10 / 400 is represented by averaging the values ​​measured in the rolling direction (RD direction) and the rolling perpendicular direction (TD direction). More specifically, the non-oriented electrical steel sheet according to one embodiment of the present invention has iron loss (W 10 / 400 ) is 9.0 to 15.8 W / Kg, and magnetic flux density (B 50 ) can be 1.62T to 1.70T.

[0109]

[0110] 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 step of manufacturing a cold-rolled sheet by cold-rolling the hot-rolled steel sheet; and a cold-rolled sheet annealing step of annealing the cold-rolled sheet.

[0111] Below, each step is explained in detail.

[0112] First, the slab is hot-rolled.

[0113] As the alloy composition of the slab has been explained in the aforementioned section on the alloy composition of hot-rolled steel sheets for non-oriented electrical steel sheets, a redundant explanation is omitted. Since the alloy composition does not substantially change during the manufacturing process of electrical steel sheets, the alloy composition of electrical steel sheets, slabs, and hot-rolled steel sheets is substantially the same.

[0114] Specifically, the slab contains Si: 1.5 to 5.0%, Al: 0.1 to 2.5%, Mn: 0.1 to 2.5% by weight, and the remainder is Fe and unavoidable impurities.

[0115] As other additional elements have been explained in the section on the alloy composition of hot-rolled steel sheets for non-oriented electrical steel sheets, redundant explanations are omitted.

[0116] The slab can be heated before hot rolling. The heating temperature of the slab is not limited, but the slab can be heated to 1200°C or lower. 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 inhibit grain growth and reduce magnetism.

[0117] Next, a hot-rolled plate is manufactured by hot-rolling a slab. The thickness of the hot-rolled plate may be 1.0 to 4.5 mm. In the step of manufacturing the hot-rolled plate, the finish rolling temperature may be 800°C or higher. Specifically, it may be 800 to 1000°C. The hot-rolled plate may be coiled at a temperature of 600°C or higher. More specifically, the thickness of the hot-rolled plate may be 1.5 to 3.5 mm.

[0118] After manufacturing hot-rolled steel sheets, annealing of the hot-rolled sheets may be performed before cold rolling. During the annealing of the hot-rolled sheets, the cracking temperature may be 850 to 1100°C. If the annealing temperature is too low, a recrystallization structure may not form or may grow finely, resulting in a small increase in magnetic flux density; if the annealing temperature is too high, magnetic properties may actually deteriorate, and rolling workability may be poor due to deformation of the sheet shape. More specifically, the temperature range may be 830 to 1170°C. The cracking time may be 15 to 180 seconds. The annealing of the hot-rolled sheets may be omitted if necessary.

[0119] Returning to the explanation of the manufacturing method for non-oriented electrical steel sheets, a cold-rolled sheet is produced by cold-rolling a hot-rolled steel sheet. At this time, cold rolling can be performed with a reduction rate of 30 to 80%. 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 The recrystallization of the grains is promoted and the grains become finer, which may cause problems such as reduced magnetic flux density and increased iron loss. More specifically, the reduction ratio may be 40 to 70%. The thickness may be 0.1 mm to 0.3 mm. More specifically, it may be 0.15 to 0.25 mm. 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.

[0120] Cold rolling can be performed as a single step if necessary, or as two steps with intermediate annealing in between. In either case, the final reduction rate must be in the range of 30 to 80% to ensure excellent magnetism through proper texture control.

[0121] Next, the cold-rolled steel sheet is annealed. In the process of annealing the cold-rolled sheet, there are generally no significant restrictions on the annealing temperature as long as it is a temperature typically applied to non-oriented electrical steel. The iron loss of non-oriented electrical steel is closely related to the grain size. The iron loss of non-oriented electrical steel can be classified into hysteresis loss and eddy current loss; hysteresis loss decreases as the grain size increases, while conversely, eddy current loss increases as the grain size increases. Consequently, there exists an optimal grain size at which the sum of hysteresis loss and eddy current loss is minimized. Therefore, it is important to determine and apply an annealing temperature that can secure the optimal grain size, and the annealing temperature can be between 850 and 1100°C. If the annealing temperature is too low, the grains become too fine, increasing hysteresis loss; if it is too high, the grains become too coarse, increasing eddy current loss and potentially resulting in inferior iron loss. More specifically, annealing can be performed at 900 to 1050°C.

[0122] During the cold-rolled sheet annealing stage, the following Equation 1 is satisfied at the exit side of the annealing furnace.

[0123] [Equation 1]

[0124] 0.15 ≤ (TR max - TR min ) / TR ave ≤ 0.45

[0125] (TR in Equation 1 ave , TR max and TR min Average tension, maximum tension, and minimum tension (kgf / mm²) in a 100m section of silver steel plate 2 It represents ).

[0126] When the tension varies within a specific range, the material is subjected to repetitive tensile and compressive stresses in the longitudinal direction, and in this process, the development of magnetic texture and the distribution of residual stress can be realized. More specifically, the value of Equation 1 can be 0.17 to 0.40.

[0127] Specifically, average tension (TR) in the 100m section ave) is 0.2 to 1.5 kgf / mm 2 This can be. Maximum tension (TR max ) is 0.30 to 2.20 kgf / mm 2 This can be. Minimum tension (TR min ) is 0.20 to 1.50 kgf / mm 2 This can be.

[0128] After the annealing step of the cold-rolled sheet, a step of forming an insulating film on the steel sheet may be further included to ensure insulation and corrosion resistance. Since the insulating film is widely known, a detailed description is omitted.

[0129]

[0130] 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.

[0131]

[0132] Example 1

[0133] A slab was manufactured with the composition shown in Table 1 below. The remainder is Fe and unavoidable impurities. The slab was heated to 1180°C and hot-rolled to a thickness of 2.1 mm at a finishing temperature of 850°C.

[0134] The manufactured hot-rolled steel sheet was annealed at 1000°C for 50 seconds. Then, the annealed hot-rolled sheet was pickled, cold-rolled to a thickness of 0.2 mm, and subsequently, finally annealed at 1000°C for 50 seconds. The tension was controlled at the exit side of the annealing furnace as shown in Table 1.

[0135] The orientation of the grains was determined using EBSD with an error range of 5°, and the average grain size and KAM values ​​were measured for a cross-section perpendicular to the ND direction and summarized in Table 2 below.

[0136] The thermal shrinkage rate was measured in the rolling direction while cooling at a rate of 1℃ / s after heat treatment at a temperature of 900 ℃ for 10 seconds, and the results are summarized in Table 2.

[0137] Si(wt%)Mn(wt%)Al(wt%)TR ave (kgf / mm 2 )TR max (kgf / mm 2 )TR min (kgf / mm 2Formula 1 Invention Example 1 4.02.02.40.70.880.660.31 Invention Example 2 4.01.12.40.40.530.390.35 Invention Example 3 2.50.21.41.52.161.500.44 Invention Example 4 2.00.11.41.21.251.070.15 Invention Example 5 4.00.32 .50.60.860.600.43 Invention Example 61.60.20.10.50.620.420.40 Invention Example 72.31.52.21.41.511.300.15 Invention Example 84.10.91.30.60.650.490.27 Invention Example 92.81.70.40.70.840.68 0.23 Invention Example 10 2.9 1.6 2.2 1.1 1.2 5 1.0 3 0.20 Invention Example 11 2.2 2.5 0.2 1.1 1.4 9 1.0 6 0.3 9 Invention Example 12 3.6 0.6 1.8 0.8 0.8 5 0.6 9 0.2 0 Invention Example 13 2.6 2.4 1.4 1.0 1.2 3 0.9 7 0.2 6 Invention Example 1 43.91.31.70.40.530.370.40 Invention Example 152.81.81.31.41.571.010.40 Invention Example 162.01.21.30.40.420.320.25 Invention Example 173.51.60.51.41.681.120.40 Invention Example 183.11.21. 50.30.340.240.33 Invention Example 194.00.71.00.50.590.410.36 Invention Example 204.01.60.10.30.420.290.43 Invention Example 214.82.40.11.11.450.950.45 Invention Example 222.20.32.31.41.69 1.270.30 Invention Example 234.81.31.30.40.530.400.33 Invention Example 244.51.61.60.70.760.450.44 Invention Example 252.90.50.41.41.641.240.29 Invention Example 262.31.70.50.30.370.270.33 Honor 273.9 1.40.10.40.5 10.370.35 Comparative Example 11.60.20.10.70.9 50.8 50.14 Comparative Example 22.3 1.5 2.20.50.4 30.370.12 Comparative Example 33.60.6 1.8 1.51.7 21.5 30.13 Comparative Example 42.20.3 2.3 0.50.530.460.14 Comparative Example 54.81.31.30.30.310.270.13 Comparative Example 64.51.61.61.11.250.740.46 Comparative Example 73.51.60.51.11.480.950.48 Comparative Example 83.11.21.50.81.200.830.46 Comparative Example 94.00.71.01.01.300.830.47 Comparative Example 102.81.70.40.40.640.450.48.

[0138] Grain size [㎛] KAM [°] 880~750 ℃ ​​Thermal shrinkage rate (×10 -5 (mm / mm·K)700~550 ℃ Thermal shrinkage rate (×10 -5mm / mm·K){001} <110> {110} <110> {001} <110> / {110} <110> {001} <110> {111} <112> {001} <110> / {111} <112> Invention Example 1 140931.510.400.490.821.441.37 Invention Example 2 126841.500.400.450.891.441.37 Invention Example 3 140931.510.400.470.851.621.40 Invention Example 4121811.490.370.570.651.621.40 Invention Example 5 130871.490.380.460.831.571.41 Invention Example 6 1441031.400.360.540.671.571.44 Invention Example 7 145851.710.400.490.821. 571.44 Invention Example 8125961.300.380.580.661.571.44 Invention Example 9127981.300.360.540.671.761.51 Invention Example 10143891.610.390.620.631.761.51 Invention Example 111301081.200.360.470.771.671.51 Invention Example 12144901.600.400.450.891.671.51 Invention Example 131451041.390.370.510.731.761.51 Invention Example 14126971.300.3 70.540.691.761.51 Invention Example 151411011.400.350.490.711.801.53 Invention Example 16133891.490.400.590.681.801.53 Invention Example 17135961.410.390.520.751.711.53 Invention Example 181281071.200.380.450.841.711.53 Invention Example 19121861.410.400.520.771.711.53 Invention Example 201431101.300.400.470.851.801.56 Invention Example 21130811.600.380.530.721.801.56 Invention Example 221311091.200.380.470.811.801.58 Invention Example 23142891.600.370.510.731.801.60 Invention Example 24146861.700.400.460.871.801.60 Invention Example 25133891.490.400.530.751.801.60 Invention Example 26147921.600.360.440.821.851.61 Invention Example 27140881.590.390.480.811.851.64 Comparative Example 1 1251141.100.380.381.001.861.66 Comparative Example 2 1361361.000.310.281.111.861.67 Comparative Example 3 1331211.100.390.351.111.871.66 Comparative Example 4 1451610.900.350.291.211.871.68 Comparative Example 5 1281161.100.370.341.091.87 1.66 Comparative Example 6 1491491.000.390.331.181.881.67 Comparative Example 7 1521690.900.330.251.321.861.66 Comparative Example 8 1351351.000.360.361.001.871.68 Comparative Example 9 1311460.900.320.291.101.881.67 Comparative Example 101231121.100.390.351.111.891.66.

[0139] As shown in Tables 1 and 2, it can be confirmed that when the steel composition is properly controlled and the tension on the exit side of the annealing furnace is properly controlled, the thermal shrinkage rate is properly controlled. In addition, it can be confirmed that when the tension on the exit side of the annealing furnace is not properly controlled, the thermal shrinkage rate is not properly controlled.

[0140]

[0141] 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 2.5%, Mn: 0.1 to 2.5%, and the remainder being Fe and unavoidable impurities, and {110} <110> {001} for the average grain size of crystal grains having an angle within 5° from <110> Non-oriented electrical steel sheet having a ratio of average grain size of crystal grains having an angle within 5° from 1.2 or greater.

2. In Paragraph 1, When the thermal shrinkage rate in the rolling direction was measured while cooling at 1℃ / s after heat treatment at 900℃ for 10 seconds, 1.40 × 10⁻⁶ in the range of 880 to 750 ℃ -5 mm / mm·K to 1.85 × 10⁻⁶ -5 mm / mm·K and; 1.35 × 10⁻⁶ in the range of 700 to 550 ℃ -5 mm / mm·K to 1.65 × 10⁻⁶ -5 Non-oriented electrical steel sheet with mm / mm·K.

3. In Paragraph 1, {111} <112> {001} for the KAM value of grains having an angle within 5° from <110> Non-oriented electrical steel sheet having a ratio of KAM values ​​of grains having an angle within 5° from 0.9 or less.

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: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, 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: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 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 2.5%, Mn: 0.1 to 2.5%, and the remainder being Fe and unavoidable impurities; A step of manufacturing a cold-rolled plate by cold-rolling the above hot-rolled steel plate and Cold-rolled plate annealing step for annealing the above-mentioned cold-rolled plate; Includes, A method for manufacturing a non-oriented electrical steel sheet satisfying the following Equation 1 at the annealing furnace exit side during the above cold-rolled sheet annealing step. [Equation 1] 0.15 ≤ (TR max - HI min ) / TR ave ≤ 0.45 (TR in Equation 1 ave , TR max and TR min Average tension, maximum tension, and minimum tension (kgf / mm²) in a 100m section of silver steel plate 2 It represents ).

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: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, 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: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 wt% or less.