KR20230094468A - Non-oriented electrical steel sheet and method for manufacturing the same - Google Patents

Abstract

In the non-oriented electrical steel sheet according to an embodiment of the present invention, by weight, Si: 1.4 to 3.0%, Mn: 0.001 to 1.5%, Al: 0.001 to 0.2%, P: 0.001 to 0.1%, C: 0.0005 to 0.005 %, S: 0.010% by weight or less (excluding 0%), N: 0.001 to 0.005%, Ti: 0.0005 to 0.005%, Sb: 0.001 to 0.08%, the balance consisting of Fe and other unavoidable impurities, steel sheet It is a non-oriented electrical steel sheet with an occupancy rate of 30% or less on the surface of stripes parallel to the rolling direction in the longitudinal direction of (Here, the stripe formed on the surface of the steel plate protrudes 1.5 μm or more from the surface, has a width of 1.5 μm or more, and a length of 10 mm or more.)

Description

Non-oriented electrical steel sheet and its manufacturing method {NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME}

An embodiment of the present invention relates to a non-oriented electrical steel sheet and a manufacturing method thereof. Specifically, one embodiment of the present invention relates to a non-oriented electrical steel sheet having excellent surface properties and excellent magnetic flux density and iron loss by optimizing alloy components and process conditions, and a manufacturing method thereof.

A motor or generator is an energy conversion device that converts electrical energy into mechanical energy or mechanical energy into electrical energy, and as regulations on environmental conservation and energy saving are recently strengthened, the demand for improving the efficiency of motors or generators is increasing. Such motors, generators, and small transformers use iron core materials, and since non-oriented electrical steel sheets are mainly used as the materials for iron cores, the characteristics of electrical steel sheets should be further improved.

Energy efficiency in a motor or generator is the ratio of input energy to output energy, and in order to improve efficiency, it is important how much energy loss such as iron loss, copper loss, and mechanical loss that is lost in the energy conversion process can be reduced. The iron loss and magnetic flux density of the commonly known non-oriented electrical steel sheet affect the iron loss and copper loss of the motor. Here, iron loss refers to energy that is converted into heat and disappears during the energy conversion process, and magnetic flux density refers to the power that generates power.

In addition, the surface characteristics of the electrical steel sheet may cause additional iron loss or mechanical damage due to processing errors that may occur during processing of the electrical steel sheet and shape differences that may occur when stacking electrical steel sheets. Therefore, in order to improve the energy efficiency of the motor, it is necessary to develop a non-oriented electrical steel sheet having excellent magnetic properties as well as having excellent surface characteristics.

As a method for lowering the iron loss of the non-oriented electrical steel sheet, there is a method of increasing the addition amount of Si, Al, and Mn, which are elements having high specific resistance. Increasing the addition amount of Si, Al, and Mn increases the specific resistance of the steel and reduces the eddy current loss of the non-oriented electrical steel sheet, thereby reducing iron loss. However, as the addition amount of these elements increases, the iron loss unconditionally decreases in proportion to the addition amount no. In addition, since the magnetic flux density decreases when the addition amount of the alloy element is increased, it is not easy to simultaneously secure excellent magnetic flux density while lowering the iron loss.

It is a method that can simultaneously improve either iron loss or magnetic flux density without sacrificing either, forming a large number of {100} and {110} textures favorable to magnetism and reducing {111} and {112} textures unfavorable to magnetism. There is a way to form it. As a method for improving the texture of such a non-oriented electrical steel sheet, a technique of performing a hot-rolled sheet annealing process in a step before cold-rolling a hot-rolled sheet after hot-rolling a slab has been used.

However, there is a problem that the manufacturing cost increases when a process called a hot-rolled sheet annealing process is added to improve the texture. In addition, when the hot-rolled sheet annealing process is added, the grains of the steel are coarsened and the cold-rollability is deteriorated.

Therefore, in the case of manufacturing a non-oriented electrical steel sheet capable of exhibiting excellent magnetism without performing a hot-rolled sheet annealing process, manufacturing cost can be reduced and the problem of productivity according to the hot-rolled sheet annealing process can be solved.

However, when the hot-rolled sheet annealing is omitted, it is a temperature region in which phase transformation may occur depending on the amount of additives such as Si, Al, and Mn, and at the same time, differences in the composition of the oxide layer and the degree of dynamic recrystallization during hot rolling occur. This change causes defects such as stripes on the surface of the non-oriented electrical steel sheet to deteriorate the surface characteristics, thereby greatly affecting the efficiency of the motor.

One embodiment of the present invention is to provide a non-oriented electrical steel sheet and a manufacturing method thereof. Specifically, one embodiment of the present invention is to provide a non-oriented electrical steel sheet having excellent surface properties and magnetic properties at the same time and a method for manufacturing the same by controlling alloy components and optimizing processing conditions during hot rolling at the same time.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, by weight, Si: 1.4 to 3.0%, Mn: 0.001 to 1.5%, Al: 0.001 to 0.2%, P: 0.001 to 0.1%, C: 0.0005 to 0.005 %, S: 0.010% by weight or less (excluding 0%), N: 0.001 to 0.005%, Ti: 0.0005 to 0.005%, Sb: 0.001 to 0.08%, the balance consisting of Fe and other unavoidable impurities, steel sheet It is a non-oriented electrical steel sheet with an occupancy rate of 30% or less on the surface of stripes parallel to the rolling direction in the longitudinal direction of

(Here, the stripe formed on the surface of the steel plate protrudes 1.5 μm or more from the surface, has a width of 1.5 μm or more, and a length of 10 mm or more.)

In the non-oriented electrical steel sheet, the total amount of C, S, and N among the constituent elements may be 0.01% or less.

In addition, the non-oriented electrical steel sheet may have a magnetic flux density (B50) of 1.65 (Tesla) or more and an iron loss (W15/50) of 4.0 W/kg or less.

Non-oriented electrical steel sheet according to another embodiment of the present invention, by weight, Si: 1.4 ~ 3.0%, Mn: 0.001 ~ 1.5%, Al: 0.001 ~ 0.2%, P: 0.001 ~ 0.1%, C: 0.0005 ~ 0.005 %, S: 0.010% by weight or less (excluding 0%), N: 0.001 to 0.005%, Ti: 0.0005 to 0.005%, Sb: 0.001 to 0.08%, the balance consisting of Fe and other unavoidable impurities, steel sheet Further provided is a non-oriented cold rolled steel sheet in which the surface portion occupancy of stripes parallel to the rolling direction in the longitudinal direction of is 30% or less. (Here, the stripe formed on the surface of the steel plate protrudes 1.5 μm or more from the surface, has a width of 1.5 μm or more, and a length of 10 mm or more.)

In a method for manufacturing a non-oriented electrical steel sheet according to another embodiment of the present invention, Si: 1.4 ~ 3.0%, Mn: 0.001 ~ 1.5%, Al: 0.001 ~ 0.2%, P: 0.001 ~ 0.1%, C : 0.0005 to 0.005%, S: 0.010% by weight or less (excluding 0%), N: 0.001 to 0.005%, Ti: 0.0005 to 0.005%, Sb: 0.001 to 0.08%, the balance being Fe and unavoidable impurities Preparing a slab comprising; heating the slab; Preparing a hot-rolled sheet by hot-rolling the slab; And cold-rolling the hot-rolled sheet to produce a cold-rolled sheet, wherein in the hot-rolled sheet manufacturing step, the hot finish rolling is performed in the range of 870 to 950 ° C., and the final pass during the hot finish rolling The rolling load (Roll force) is 0.352 ton / mm to 0.480 ton / mm, and the final pass (pass) reduction ratio is 13.5% to 18% to perform the hot finish rolling.

As such, the hot-rolled hot-rolled sheet may be wound into a coil at a temperature of 650° C. to 800° C.

And the step of heating the slab may be heated for 0.1 to 3 hours at 1,100 to 1,250 ℃.

In addition, the intermediately prepared hot-rolled sheet may be pickled for 20 seconds to 200 seconds by diluting hydrochloric acid (HCl) in H2O at 3.0% to 22.5% by weight.

When performing cold rolling as above, it is preferable to perform cold rolling with a final reduction ratio of 65 to 90%.

In addition, in the non-directional manufacturing method according to another embodiment of the present invention, the step of final annealing the cold-rolled sheet at 900 to 1,070 ℃ may be further included.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, even if hot-rolled sheet annealing is omitted, the dynamic recrystallization generating components such as Si, Al, and Mn, and the amount of C, S, and N are precisely controlled, and the hot rolling process It is possible to provide a non-oriented electrical steel sheet having excellent magnetic properties by simultaneously securing excellent magnetic flux density while lowering iron loss by controlling detailed conditions.

The non-oriented electrical steel sheet according to an embodiment of the present invention can provide a non-oriented electrical steel sheet with excellent surface quality by controlling the components of alloy elements and controlling the detailed conditions of the hot rolling process, even though hot-rolled sheet annealing is omitted. can

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

The terminology used herein is only for referring to specific embodiments and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising" as used herein specifies particular characteristics, regions, integers, steps, operations, elements and/or components, and the presence or absence of other characteristics, regions, integers, steps, operations, elements and/or components. Additions are not excluded.

When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part or may be followed by another part therebetween. In contrast, when a part is said to be “directly on” another part, there is no intervening part between them.

Although not defined differently, all terms including technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with related technical literature and currently disclosed content, and are not interpreted in ideal or very formal meanings unless defined.

In addition, unless otherwise specified, % means weight%, and 1ppm is 0.0001 weight%.

In one embodiment of the present invention, the meaning of further including an additional element means replacing and including iron (Fe) as much as the additional amount of the additional element.

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

Resistivity elements such as Si, Al, and Mn added to lower the iron loss of the non-oriented electrical steel sheet can lower the saturation magnetic flux density of the material. In addition, as these elements are added, the strength of the steel sheet increases, and as a result, there has been a problem of shortening the life of the mold during punching.

Therefore, it is necessary to improve the texture of the non-oriented electrical steel sheet so that it can have low strength while increasing magnetic flux density while lowering iron loss.

In addition, as one of the defects of the non-oriented electrical steel sheet, stripes are generated on the surface of the steel sheet, which deteriorates the surface characteristics. One of the causes of streaks on the surface of the steel sheet may be due to a difference in strain according to a rolling force when different crystal structures are rolled.

Therefore, in one embodiment of the present invention, in order to improve the streaks caused by such rolling and to minimize the strain between different crystal structures in the hot rolling step, the optimal rolling temperature and rolling force were derived through many experiments. When the hot rolling temperature rises, the strength of the material is lowered, and thus the deviation of mechanical properties between different crystal structures is reduced.

In addition, when the rolling reduction force is increased during hot rolling, the degree of rolling reduction by a strong load is reduced, and when the rolling reduction force is operated at a high rolling temperature, stripe defects occurring in the non-oriented electrical steel sheet can be reduced.

Hereinafter, an embodiment of the present invention will be described in order of composition and manufacturing process of a steel sheet.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, by weight, Si: 1.4 to 3.0%, Mn: 0.001 to 1.5%, Al: 0.001 to 0.2%, P: 0.001 to 0.1%, C: 0.0005 to 0.005 %, S: 0.010 wt% or less (excluding 0%), N: 0.001 to 0.005%, Ti: 0.0005 to 0.005%, Sb: 0.001 to 0.08%, and the balance includes Fe and unavoidable impurities.

First, the reason for limiting the components of the non-oriented electrical steel sheet will be explained.

[Si: 1.4 to 3.0% by weight]

Silicon (Si) is a major element added to reduce eddy current loss among iron losses by increasing the resistivity of steel. If too little Si is added, a problem of iron loss deterioration occurs. Therefore, increasing the content of Si is advantageous in terms of iron loss, but if too much Si is added, price competitiveness is lowered, magnetic flux density is greatly reduced, and problems in workability may occur. In addition, Si is a representative ferrite stabilization element and is an element related to phase transformation during hot rolling. More specifically, 1.4 to 2.6 wt % of Si may be included.

[Mn: 0.001 to 1.5% by weight]

Manganese (Mn), along with Si and Al, is an element that increases resistivity to lower iron loss, forms sulfide, stabilizes austenite structure, induces phase transformation during hot rolling, and improves texture. . If too little Mn is added, sulfides may be finely precipitated to deteriorate magnetism. Conversely, if too much Mn is added, the formation of {111} texture, which is unfavorable to magnetism, may be promoted and the magnetic flux density may decrease. Therefore, in consideration of this point, Mn may be included in a range that is neither small nor large. More specifically, 0.3 to 1.4 wt% of Mn may be included.

[Al: 0.001 to 0.2% by weight]

Aluminum (Al) plays an important role in reducing iron loss by increasing specific resistance along with Si, and also improves rollability or improves workability during cold rolling. If too little Al is added, there is no effect on reducing high-frequency iron loss, and the precipitation temperature of AlN is lowered, so that fine nitride is formed and magnetism may be deteriorated. Conversely, if too much Al is added, nitride is excessively formed, deteriorating magnetism, and causing problems in all processes such as steelmaking and continuous casting, which can greatly reduce productivity. Also, as a ferrite stabilizing element, it affects the phase transformation during hot rolling. Therefore, Al may be included in an amount of 0.2% by weight or less, more preferably 0.178% by weight or less.

[P: 0.001 to 0.100% by weight]

Phosphorus (P) not only serves to increase the specific resistance of the material, but also segregates at the grain boundary to improve the texture to increase the specific resistance and lower the iron loss, so it can be additionally added. However, too much addition of P results in the formation of a texture that is unfavorable to magnetism, so there is no effect on improving the texture, and excessive segregation at grain boundaries reduces rollability and workability, making production difficult. Therefore, P may be added in the above range. More specifically, 0.001 to 0.050% by weight of P may be included.

[Sb: 0.001 to 0.080% by weight]

Antimony (Sb) segregates on grain boundaries and surfaces to improve the texture of the material and suppresses surface oxidation, so it can be additionally added to improve magnetism. If too much Sb is added, grain boundary segregation becomes severe, resulting in deterioration of surface quality, and an increase in hardness, resulting in breakage of the cold-rolled sheet, deterioration in rollability, and peeling of the coating layer after final annealing. Therefore, Sb may be added within the above range. However, if the amount of Sb added is too small, the effect of improving texture and inhibiting surface oxidation cannot be expected. More specifically, 0.01 to 0.07% by weight of Sb may be included.

[C: 0.0005 to 0.005% by weight]

Carbon (C) combines with Ti, Nb, etc. to form carbides to deteriorate magnetism, and when used after processing from final products to electrical products, iron loss increases due to magnetic aging, which can reduce the efficiency of electrical devices. More specifically, it may further include C in an amount of 0.0005 to 0.002% by weight.

[S: 0.010% by weight or less (excluding 0%)]

Sulfur (S) is preferably added as low as possible because it forms fine sulfides inside the base material to suppress crystal grain growth and weaken iron loss. When a large amount of S is included, it may combine with Mn to form precipitates or cause high temperature brittleness during hot rolling. Accordingly, S may be further included in an amount of 0.0100% by weight or less. Specifically, it may further include 0.001 to 0.005% by weight or less of S.

[N: 0.001 to 0.005% by weight]

Nitrogen (N) not only forms fine and long precipitates inside the base material by combining with Al and Ti, but also deteriorates iron loss by combining with other impurities to form fine nitrides and inhibiting crystal grain growth, so it is desirable to contain less. . In one embodiment of the present invention, N may further include 0.005% by weight or less. More specifically, 0.001 wt % to 0.003 wt % of N may further be included.

Here, the total amount of C, S, and N can be controlled to 0.01 wt% or less. In non-oriented electrical steel sheets containing Si and Al, C, S, and N are elements that form precipitates such as carbides, sulfides, and nitrides. contribute to increasing the density.

[Ti: 0.0005 to 0.005% by weight]

Titanium (Ti) is an element that has a very strong tendency to form precipitates in steel, and forms fine carbides or nitrides inside the base material to suppress crystal grain growth. Therefore, the more added, the more carbides and nitrides are formed, suppressing the formation of a texture favorable to magnetism. So, it degrades the self. In one embodiment of the present invention, Ti may be further included at 0.005% by weight or less. More specifically, Ti may be further included in an amount of 0.0005 to 0.003% by weight or less.

The non-oriented electrical steel sheet according to an embodiment of the present invention may further include other unavoidably included elements in addition to the above components.

Inevitable impurities refer to impurities that are intentionally introduced or unavoidably mixed during the manufacturing process of steelmaking and non-oriented electrical steel sheet. Since unavoidable impurities are widely known, detailed descriptions are omitted. In addition, an embodiment of the present invention does not exclude the addition of elements other than the above-described alloy components, and may be variously included within a range that does not impair the technical spirit of the present invention. When additional elements are included, they are included in place of Fe, which is the remainder.

In the non-oriented electrical steel sheet having the above composition, the occupancy of the surface portion of stripes parallel to the rolling direction in the longitudinal direction of the steel sheet may be 30% or less. Here, the stripe formed on the surface of the steel sheet protrudes 1.5 μm or more from the surface, has a width of 1.5 μm or more, and a length of 10 mm or more. And, the occupancy rate of the stripe is the ratio of the length of the area where the stripe exists to the total length of the cold-rolled coil.

A non-oriented electrical steel sheet according to an embodiment of the present invention means a steel sheet on which the final annealing process has been completed or a cold-rolled steel sheet on which cold rolling has been completed. Therefore, the stripes that can be formed on the surface of the steel sheet are formed during the cold rolling process in which physical pressing force is applied in the steel sheet manufacturing process, and mean that additional external pressure is no longer applied in the subsequent process, and the stripes formed during the cold rolling process can be seen as being present on the surface of the steel sheet even in the subsequent process.

It was confirmed that the non-oriented electrical steel sheet according to an embodiment of the present invention had an iron loss of 4.0 W/kg or less and a magnetic flux density of 1.62 or more. Here, the iron loss (W15/50) means the average loss (W/Kg) in the rolling direction and in the vertical direction when the magnetic flux density of 1.5 Tesla is maintained at a frequency of 50 Hz. And the magnetic flux density (B50) means the magnitude (Tesla) of the magnetic flux density induced when a magnetic field of 5,000 A/m is applied.

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

In the manufacturing method of a non-oriented electrical steel sheet according to an embodiment of the present invention, Si: 1.4 ~ 3.0%, Mn: 0.001 ~ 1.5%, Al: 0.001 ~ 0.2%, P: 0.001 ~ 0.1% , C: 0.0005 to 0.005%, S: 0.010 wt% or less (excluding 0%), N: 0.001 to 0.005%, Ti: 0.0005 to 0.005%, Sb: 0.001 to 0.08%, the balance being Fe and unavoidable Preparing a slab containing impurities; heating the slab; Preparing a hot-rolled sheet by hot-rolling the slab; Cold-rolling the hot-rolled sheet to produce a cold-rolled sheet and final annealing the cold-rolled sheet.

Hereinafter, each step is described in detail.

First, the step of manufacturing the slab will be described. Since the reason for limiting the constituent elements in the slab is the same as the reason for limiting the composition of the non-oriented electrical steel sheet described above, repeated descriptions will be omitted. Since the composition of the slab is not substantially changed during manufacturing processes such as hot rolling, cold rolling, and final annealing, which will be described later, the composition of the slab and the composition of the non-oriented electrical steel sheet are substantially the same.

The slab may be heated prior to manufacturing the hot-rolled sheet. Specifically, the slab may be charged into a heating furnace and heated at 1,100 to 1,250 ° C for 0.1 to 3 hours. If the slab heating temperature is too high, precipitates such as AlN and MnS present in the slab are re-dissolved and then finely precipitated during hot rolling and annealing, thereby suppressing crystal grain growth and deteriorating magnetism. Slab heating may be specifically heated for 0.1 to 2 hours at a temperature range of 1,130 to ,1200 ℃.

Next, the heated slab is hot-rolled to produce a hot-rolled sheet. The thickness of the hot-rolled sheet by hot rolling may be 1.6 mm to 2.7 mm. Specifically, the thickness of the hot-rolled sheet may be 2.0 mm to 2.5 mm.

In the method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention, in the step of manufacturing a hot-rolled sheet, a finish rolling temperature may be 870°C to 950°C. In the step of manufacturing the hot-rolled sheet, the pass roll force of the last pass during finish rolling may be 0.352 ton/mm or more and 0.480 ton/mm or less based on the steel sheet width of 1,250 mm. In addition, the rolling reduction of the last pass during hot rolling finish rolling may be 13.5% or more and 18% or less. When the rolling load is 0.352 ton/mm and the reduction ratio is 13.5% or less, the deformation rate is low, and the driving force for recrystallization after winding is weak, which may increase the degree of streak generation. It is advantageous in terms of recrystallization driving force, but it is preferable to make it less than that because the shape of the plate deteriorates and cold rolling becomes difficult.

As described above, the hot-rolled sheet passing through the last pass of hot rolling may be wound in a coil state at a temperature of 650 ° C to 800 ° C.

Next, the hot-rolled sheet is pickled and cold-rolled to a predetermined sheet thickness. Here, pickling of the hot-rolled sheet may be performed for 20 seconds to 200 seconds by diluting hydrochloric acid (HCl) in H2O at 3.0% to 22.5% by weight. Cold rolling can be carried out over 3 to 7 passes. The reduction ratio of cold rolling may be applied differently depending on the thickness of the hot-rolled sheet, but cold rolling may be performed so that the final thickness is 0.35 to 0.65 mm by applying a final reduction ratio of 65 to 90% during cold rolling.

The final cold-rolled cold-rolled sheet may further be subjected to final annealing. It can be cracked at 900 to 1,070 ℃ in the final annealing step. In order to optimize grain boundary segregation, it is better to lower the annealing temperature, but if the plate thickness becomes thinner, the annealing temperature should be increased. If the soaking zone temperature is less than 900 ℃, recrystallization does not occur sufficiently, and if the final annealing temperature exceeds 1,070 ℃, the segregation effect disappears.

When cooling after soaking, cooling may be performed at a cooling rate of 10 to 40 °C/s up to 700 °C after soaking temperature. The cooling rate is controlled within a range in which the high-frequency iron loss is not deteriorated due to the excessive growth of the crystal grain size. More specifically, it may be cooled at a rate of 15 to 35 °C / s.

Thereafter, a step of forming an insulating layer may be further included. Since a method of forming an insulating layer is widely known in the field of non-oriented electrical steel sheet technology, a detailed description thereof will be omitted.

Preferred examples and comparative examples of the present invention are described below. However, the following example is only a preferred embodiment of the present invention, but the present invention is not limited to the following example.

Example

A slab having the composition shown in Table 1 below was prepared. These slabs were heated in the range of 1,130 ° C. to 1200 ° C., subjected to hot rolling, and then hot finished rolled in the range of 870 to 950 ° C. to produce hot-rolled sheets having plate thicknesses of 2.0 mm, 2.3 mm, and 2.5 mm. The pass roll force of the last pass of the hot finish rolling was 0.352 ton/mm or more and 0.480 ton/mm based on the steel sheet width of 1,250 mm, and the reduction ratio was 13.5% or more. After hot rolling, it was wound within the range of 650 ° C to 800 ° C.

The coiled hot-rolled sheet was cooled in air and then pickled.

Then, by cold rolling at a reduction ratio of 70 to 90%, cold-rolled steel sheets were manufactured with a sheet thickness of 0.35 mm and 0.5 mm. The manufactured cold-rolled steel sheet was shown in Table 2 below by measuring the occupancy rate of stripes on the surface.

The stripe occupancy rate on the surface of the steel sheet was measured by measuring the length of the stripe generated in the cold-rolled steel sheet length of 1,000m or more in the rolling direction, and the ratio was obtained using the total length of the cold-rolled steel sheet.

steel grade Si
(%) Mn
(%) Al
(%) P
(%) C
(%) S
(%) N
(%) Ti
(%) Sb
(%) C,S,N sum
(%) One 1.84 0.67 0.252 0.007 0.0008 0.0012 0.0013 0.0021 0.01 0.0033 2 2.05 0.75 0.18 0.022 0.0012 0.0019 0.0015 0.0010 0.03 0.0046 3 1.85 0.54 0.002 0.014 0.0013 0.0009 0.0017 0.0017 0.04 0.0039 4 2.04 0.7 0.012 0.007 0.0016 0.0016 0.0013 0.0008 0.03 0.0045 5 1.65 0.62 0.009 0.028 0.0013 0.0014 0.0019 0.0015 0.05 0.0046 6 2.41 1.35 0.006 0.012 0.0016 0.0014 0.0016 0.0014 0.04 0.0046 7 2.18 1.28 0.008 0.008 0.0006 0.0021 0.0022 0.0008 0.03 0.0049 8 1.95 0.67 0.002 0.005 0.0022 0.0015 0.002 0.0012 0.03 0.0057 9 1.71 0.92 0.007 0.007 0.0015 0.0013 0.0013 0.0016 0.04 0.0041 10 1.85 0.56 0.003 0.011 0.0023 0.0035 0.0018 0.0009 0.05 0.0073

steel grade Reheat temperature (℃) Finish rolling temperature (℃) Finish rolling final roll force (ton/mm) Final rolling reduction ratio (%) Winding temperature (℃) Hot rolled sheet thickness (mm) Cold rolled sheet thickness (mm) Iron loss W15/50 (W/kg) Magnetic flux density B50 (T) Surface streak share (%) note 1-1 1150 887 0.439 15.7 720 2 0.35 3.76 1.7 42 comparative example 1-2 1150 901 0.427 13.8 700 2.3 0.5 4.08 1.71 53 comparative example 2-1 1160 894 0.38 14.2 680 2.3 0.5 4.07 1.69 25 example of invention 2-2 1160 914 0.422 14.7 720 2.5 0.5 3.92 1.7 21 example of invention 3-1 1180 880 0.356 12.2 680 2.3 0.35 3.52 1.74 32 comparative example 3-2 1180 915 0.342 12.8 720 2.3 0.5 3.37 1.75 38 comparative example 4-1 1150 897 0.39 15.3 680 2.3 0.5 3.08 1.73 17 example of invention 4-2 1150 925 0.371 13.6 720 2 0.35 2.78 1.73 16 example of invention 5-1 1170 883 0.429 17.1 700 2.5 0.65 3.87 1.77 27 example of invention 5-2 1170 871 0.446 16.2 680 2 0.35 3.54 1.75 5 example of invention 6-1 1200 880 0.442 15.3 700 2 0.5 2.67 1.71 8 example of invention 6-2 1200 914 0.45 13.9 700 2.5 0.5 2.84 1.7 12 example of invention 7-1 1160 887 0.462 15 680 2 0.35 2.67 1.7 17 example of invention 7-2 1160 867 0.492 14.5 680 2.3 0.35 2.74 1.7 32 comparative example 8-1 1170 882 0.424 14.8 680 2 0.35 2.92 1.72 19 example of invention 8-2 1170 890 0.429 15.2 700 2.3 0.5 3.14 1.72 22 example of invention 9-1 1180 903 0.433 15.3 680 2.5 0.5 3.42 1.74 20 example of invention 9-2 1180 875 0.502 18.2 720 2.3 cold rolling failure comparative example 10-1 1130 872 0.432 14.7 680 2.3 0.5 3.58 1.74 17 example of invention 10-2 1130 860 0.492 16.3 700 2.5 0.5 3.45 1.74 6 example of invention

As shown in Tables 1 and 2, the examples satisfying the alloy components and manufacturing process conditions have low iron loss, high magnetic flux density, and an occupancy rate of less than 30% of the stripe on the surface of the steel sheet, indicating excellent magnetic properties and excellent surface properties. You can check.

On the other hand, it can be seen that steel grades 1-1, 1-2, 3-2, and 7-2 whose alloy components are outside the scope of the present invention or do not satisfy the manufacturing process conditions have poor magnetic properties and poor surface properties.

The present invention is not limited to the above embodiments, but can be manufactured in a variety of different forms, and those skilled in the art to which the present invention pertains may take other specific forms without changing the technical spirit or essential features of the present invention. It will be understood that it can be implemented with Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

Claims (10)

In wt%, Si: 1.4 to 3.0%, Mn: 0.001 to 1.5%, Al: 0.001 to 0.2%, P: 0.001 to 0.1%, C: 0.0005 to 0.005%, S: 0.010 wt% or less (excluding 0%) ), N: 0.001 ~ 0.005%, Ti: 0.0005 ~ 0.005%, Sb: 0.001 ~ 0.08%, the balance consisting of Fe and other unavoidable impurities,
A non-oriented electrical steel sheet with an occupancy rate of 30% or less on the surface of stripes parallel to the rolling direction in the longitudinal direction of the steel sheet.
(Here, the stripe formed on the surface of the steel plate protrudes 1.5 μm or more from the surface, has a width of 1.5 μm or more, and a length of 10 mm or more.) According to claim 1,
The C, S, and N are 0.01% or less in total in the non-oriented electrical steel sheet. The magnetic flux density (B50) of the steel sheet is 1.65 (Tesla) or more and at the same time the iron loss (W15 / 50) is 4.0 W / kg or less of the non-oriented electrical steel sheet. In wt%, Si: 1.4 to 3.0%, Mn: 0.001 to 1.5%, Al: 0.001 to 0.2%, P: 0.001 to 0.1%, C: 0.0005 to 0.005%, S: 0.010 wt% or less (excluding 0%) ), N: 0.001 ~ 0.005%, Ti: 0.0005 ~ 0.005%, Sb: 0.001 ~ 0.08%, the balance consisting of Fe and other unavoidable impurities,
A non-oriented cold-rolled steel sheet in which the surface area occupancy of stripes parallel to the rolling direction in the longitudinal direction of the steel sheet is 30% or less.
(Here, the stripe formed on the surface of the steel plate protrudes 1.5 μm or more from the surface, has a width of 1.5 μm or more, and a length of 10 mm or more.) In wt%, Si: 1.4 to 3.0%, Mn: 0.001 to 1.5%, Al: 0.001 to 0.2%, P: 0.001 to 0.1%, C: 0.0005 to 0.005%, S: 0.010 wt% or less (excluding 0%) ), N: 0.001 ~ 0.005%, Ti: 0.0005 ~ 0.005%, Sb: 0.001 ~ 0.08%, the balance comprising Fe and unavoidable impurities Preparing a slab;
heating the slab;
Preparing a hot-rolled sheet by hot-rolling the slab; and
Cold-rolling the hot-rolled sheet to produce a cold-rolled sheet,
In the hot-rolled sheet manufacturing step, the hot finish rolling is finish rolling in the range of 870 to 950 ° C., and the roll force of the last pass during the hot finish rolling is 0.352 ton / mm to 0.480 ton / mm , The final pass (pass) reduction ratio is 13.5% to 18%, the manufacturing method of the non-oriented electrical steel sheet to the hot finish rolling. According to claim 5,
The method of manufacturing a non-oriented electrical steel sheet in which the hot-finish rolled hot-rolled sheet is wound in a coil state at a temperature of 650 ° C to 800 ° C. In paragraph 5,
Heating the slab is a method of manufacturing a non-oriented electrical steel sheet by heating at 1,100 to 1,250 ° C. for 0.1 to 3 hours. According to claim 5,
The hot-rolled sheet is a method for producing a non-oriented electrical steel sheet by diluting hydrochloric acid (HCl) in H2O at 3.0% to 22.5% by weight and performing pickling for 20 seconds to 200 seconds. According to claim 5,
The cold rolling is a method for producing a non-oriented electrical steel sheet that is cold rolled at a final reduction ratio of 65 to 90%. According to claim 5,
In the non-directional manufacturing method, the non-directional manufacturing method further comprising the step of final annealing the cold-rolled sheet at 900 to 1,070 ° C.