KR101227767B1 - (100)〔0vw〕 NON-ORIENTED ELECTRICAL STEEL SHEET WITH EXCELLENT MAGNETIC PROPERTIES - Google Patents

Abstract

PURPOSE: A (100)[0vw] non-oriented electrical steel sheet with excellent magnetic characteristics is provided to obtain a crystal orientation at low costs within a short time by employing heat treatment in a reducing gas atmosphere instead of in a vacuum condition. CONSTITUTION: A (100)[0vw] non-oriented electrical steel sheet with excellent magnetic characteristics comprises 0.005 wt% or less(over 0) of C, 2-4 wt% of Si, 0.05 wt% or more(under 1.0 wt%) of Mn, 0.0001-0.035 wt% of S, 0.20 wt% or less(over 0) of Al, 0.2 wt% or less(over 0) of P, 0.003 wt% or less(over 0) of N, and the remaining amount of Fe and inevitable impurities. The size of the average crystal grains on the sheet surface is equal to or greater than the thickness of the sheet.

Description

(10) [0 ｖｗ] non-oriented electrical steel sheet with excellent magnetic properties {(10) (0 ｖｗ) NON-ORIENTED ELECTRICAL STEEL SHEET WITH EXCELLENT MAGNETIC PROPERTIES}

The present invention relates to a non-oriented electrical steel sheet used as an iron core of an electric device such as a motor, a transformer, and more particularly to a (100) [0 vw] non-oriented electrical steel sheet excellent in magnetic properties.

In recent years, the use of electric equipment in the high frequency range is increasing for the purpose of high efficiency and miniaturization. In particular, as the generator for electric vehicles, the magnetic enhancement is strongly demanded in the high frequency range of 400 to 1,000 Hz.

Non-oriented electrical steel sheet is an important component necessary for converting electrical energy into mechanical energy in electrical equipment. In order to reduce energy, it is necessary to lower magnetic properties, ie, iron loss and increase magnetic flux density.

Iron loss turns into heat and disappears during the energy conversion process, and magnetic flux density appears as a power generating force. Therefore, when the magnetic flux density is high, the copper loss of an electric apparatus can be reduced and miniaturization is possible.

Iron loss may be lowered by lowering the thickness or by adding a large amount of alloying elements. However, iron loss may be made of clean steel with less impurities, or may be made of steel with improved magnetic properties by adding additional elements. In the former case, the cost of the further process is increased in the manufacturing process, and in the latter case, the cost is increased for additional elements to be added.

The production method of high quality (111) [uvw] non-oriented electrical steel sheet which is generally performed currently is about 3% of Si as main alloy, 0.5 to 1.4% of Al, 0.1 to 0.4% of Mn, and others. It is composed of unavoidable impurities and residual components, and it is possible to obtain good magnetism by lowering the slab heating temperature during hot rolling. Specifically, as the slab heating temperature is low, such as 1050 to 1150 ° C, it is possible to obtain good magnetic properties. The reason is that the reheating of the slab at a low temperature is the only method in order to prevent the generation of fine AlN and MnS which inhibit the crystal growth during the final annealing by the Winding-Rewinding method.

That is, when solidified in molten steel, AlN and MnS precipitate as coarse particles, and the AlN and MnS are redissolved when the slab is heated, and the dissolved [Al], [N], [Mn], and [S] are hot rolled. At the end of the re-precipitation of harmful AlN and MnS, the higher the slab reheating temperature, the more the dissolved [Al], [N], [Mn], and [S], and the crystal growth in the final annealing is disturbed. As a result, in order to obtain good magnetism, the slab reheating temperature must be kept low. In this case, the finishing rolling temperature is also low, and is usually about 850 ° C.

Considering the theory of alloy design, in the crystal growth that occurs in 3% silicon steel sheet, (110) [001] Goth texture is not the only final texture obtained in 3% silicon steel sheet, even in the same 3% silicon steel sheet, The surface segregation concentration of S varies according to the combination of cold rolling rate, heat treatment atmosphere, heating rate, and the surface energy of the surface grains in each crystal orientation. As a result, the above specified element values applied to the current 3% electrical steel sheet production line only minimize the surface energy of the (110) [001] surface grains by lowering the surface segregation concentration of S, and their surface energy. It can be concluded that this is only one specific combination that facilitates Surface-energy-induced selective growth, leaving only (110) [001] grains after final annealing. Segregation refers to a phenomenon in which free atoms S included in an electrical steel sheet are collected in the form of free atoms on the surface or grain boundaries during final annealing.

Figure 1 shows the ideal crystal orientation and each crystal orientation obtained by the etching-pit method, Figure 2 is N.H. The schematic diagram for demonstrating the segregation phenomenon of Heo (refer nonpatent literature 1, 2) is shown.

As shown in Fig. 2 (a), the equilibrium segregation concentration (Cs) decreases with increasing temperature, and the segregation concentration at each temperature is large as the amount of S contained in the electrical steel sheet increases. In addition, when the equilibrium segregation concentration at T ₀ of FIG. 2 (A) is Cs ₀ , the segregation concentration (I) generally increases with time as shown in FIG. 2 (b) when isothermal heat treatment at T ₀ . Thus increasing towards Cs ₀ .

However, in the heat treatment atmosphere containing hydrogen (H), the segregation concentration (II) at the surface is after a certain maximum point P because loss of the surface segregation occurs due to the H ₂ S reaction between the surface segregation S and hydrogen. The surface segregation continuously decreases with time.

On the other hand, even in the case of an isothermal heat treatment at the same temperature the electrical steel sheet of the same components, and Fig. 2 (c) the case of isothermal heat treatment at T ₀ as segregation at T ₀ in accordance with the heating rate during heating until the temperature increases visible in The concentration curve is expected to shift from II to III in the shorter time.

On the other hand, according to J. Friedel (see Non-Patent Document 3), the surface energy of the body-centered cubic metal has the lowest (110), the middle (100) and the highest surface energy of (111). high.

In addition, the surface energy of the body-centered cubic lattice has the lowest surface energy of (110) when the concentration of surface segregated S is extremely small during final annealing, but the surface energy of (100) is lowest as the surface segregated S increases, When the concentration of the surface segregated S is further increased, the surface energy of (111) is the lowest, so that only the grains having the smallest surface energy are grown according to the concentration of the surface segregated S.

3 (a) to 3 (c) show the change in surface energy according to the surface segregation concentration of S in the body-centered cubic metal, and FIG. 3 (d) shows the surface energy induced by the inventor (NH Heo). It is a schematic diagram explaining a selective crystal growth phenomenon (refer nonpatent literature 1). In other words, in the zone representing the surface segregation, the concentration C ₍₁₁₀₎ or less of S, only 100 and 111, the (110) surface energy organic optionally of the grain, while erosion grain crystal growth is taking place, C ₍₁₁₁₎ or higher (111 ) Only crystal growth of grains occurs, and only (100) grains grow at a time zone indicating surface segregation concentration between C ₍₁₁₀₎ to C ₍₁₁₁₎ .

In addition, the present inventors have completed the theory of recrystallization nucleation in modified metals (see Non-Patent Documents 4 and 5). In other words, it is theoretically demonstrated that the crystal orientation of the nucleus shows the crystal orientation similar to that of the modified mother phase when nucleation is generated from the modified metal based on the elastic theory, and this is experimentally proved using 3% silicon steel.

4 shows an Orientation Distribution Function (ODF) of a general cold rolled plate obtained from a pickled hot rolled plate. The more dense contours in the azimuth distribution function, the more strongly the crystal orientation that represents that portion is formed in the cold rolled steel sheet. Therefore, the crystal orientation of cold rolled steel sheet is the (111) [uvw] principal crystal orientation represented by (111) [112] and (111) [110], and (100) [0vw] represented by (100) [012]. It can be seen that it consists of the negative crystal orientation of.

On the other hand, research has been published on the development of (100) [0vw] non-oriented electrical steel sheet having excellent magnetic properties compared to the existing (111) [uvw] non-oriented electrical steel sheet. In studies such as T. Tomida (see Non-Patent Documents 6 and 7) and Patent Registration 10-0797895 (Patent Document 1), S is treated as an inevitable impurity. An isothermal heat treatment of a steel sheet containing a large amount of C in vacuum is performed. Phase transformation from austenite (γ) to ferrite (α) by decarburization reaction during the process of obtaining (100) [0vw] crystal orientation and from austenite (γ) during cooling of a steel sheet containing a large amount of Mn at high temperature. A method for obtaining a (100) [0vw] crystal orientation by using a phase transformation into ferrite (α) has been reported.

However, in the above-described methods for producing (100) [0vw] non-oriented electrical steel sheet, the commercialization failed due to the difficult vacuum heat treatment method and the long heat treatment time of several tens of hours.

Patent Document 1: Korean Patent Registration No. 10-0797895 (2008.01.18)

Non-Patent Document 1: Acta Materialia vol. 48, 2000, pp 2901 Non-Patent Document 2: Acta Materialia vol. 51, 2003, pp 4953 Non Patent Literature 3: Acta metall. vol. 1, 1953, pp 79 Non-Patent Document 4: Journal of the Korean Physical Society vol. 44, 2004, pp 1547 Non Patent Literature 5: Materials Letters vol. 59, 2005, pp 2827 Non-Patent Document 6: IEEE Trans. Magnetics vol. 37, 2001, pp 2318 Non-Patent Document 7: J. Magnetism and Magnetic Materials vol. 254-255, 2003, pp 315

The present invention can be produced by a short time heat treatment using a steel sheet of component composition which adds S as the most important element in the production of (100) [0vw] non-oriented electrical steel sheet and exhibits ferrite structure at all manufacturing process temperatures. It relates to a (100) [0vw] non-oriented electrical steel sheet.

That is, the present invention is applied to the nucleation theory and surface energy organic selective crystal growth method during the final annealing, and the (100) [0vw] crystal orientation present in the cold rolled sheet is annealed for a short time in a reducing gas atmosphere rather than vacuum. By using the (100) [0vw] non-oriented electrical steel sheet core material which is suitable for the iron core of a rotating machine by obtaining the (100) [0vw] crystal orientation, it is possible to obtain a low cost and a short time by using a winding-rewinding method. A main purpose is to provide a (100) [0vw] non-oriented electrical steel sheet having excellent magnetic properties and a method of manufacturing the same, which can be easily manufactured.

According to a preferred embodiment of the present invention, in weight percent, C: greater than 0 and 0.005% or less, Si: 2 to 4%, Mn: 0.05% or more and less than 1.0%, S: 0.0001 to 0.035%, Al: greater than 0 0.20 Less than or equal to P, greater than 0 and less than 0.2%, N: greater than 0 and less than 0.003%, consisting of the remaining Fe and other unavoidable impurities, characterized in that the average grain size of the plate surface is equal to or greater than the plate thickness A (100) [0vw] non-oriented electrical steel sheet having excellent magnetic properties is provided.

Here, the average grain size y and the plate thickness x of the surface of the plate represent a relationship of y ≥ 2.2x + 0.1 (unit: mm) when S is less than 0.007% by weight, and when S is 0.007% by weight or more, y ≥ 1.48x + 0.04 (unit: mm) is shown.

At this time, the first stage annealing in the first stage annealing furnace of 800 ℃ ~ 1100 ℃, preferably two stage annealing in the two stage annealing furnace of 1150 ℃ ~ 1370 ℃ higher than the temperature of the first stage annealing furnace, in each annealing furnace It is preferable that heat processing time is 10 second-600 second.

In addition, it is preferable that the said S contains more than 0.008%-0.035% or less.

Compared with (100) [0vw] non-oriented electrical steel sheet manufactured by the conventional manufacturing method of heat treatment in vacuum for a long time in vacuum using a steel sheet containing a large amount of C and Mn for phase transformation from austenite (γ) to ferrite (α) Thus, the (100) [0vw] non-oriented electrical steel sheet having excellent magnetic properties according to the preferred embodiment of the present invention is heat treated in a reducing gas atmosphere instead of vacuum using a steel plate exhibiting a ferrite structure in a pre-heating temperature section. The (100) [0vw] crystal orientation is formed easily and inexpensively in time.

Therefore, it is possible to manufacture a non-oriented electrical steel sheet by a winding-rewinding method, and there is an effect of improving productivity and reducing manufacturing costs.

Figure 1 shows the ideal crystal orientation and each crystal orientation obtained by the etching-pit method.
2 is a schematic diagram illustrating segregation phenomenon.
3 is a graph showing the change in surface energy according to the surface segregation concentration of S in the body-centered cubic lattice.
4 is a contour diagram showing an Orientation Distribution Function (ODF) of a general cold rolled plate obtained from a pickled hot rolled plate.
5 is a graph showing crystal orientation distribution of steel grade A according to Example 1;
6 is a graph showing the crystal orientation distribution of steel grade A according to Example 2;
7 is a graph showing crystal orientation distribution of steel grade A according to Example 3;
Figure 8 is a photograph showing the etch fit tissue of steel grade A according to Example 3.
9 is a graph showing crystal orientation distribution of steel grade A according to Example 4;
10 is a graph showing the crystal orientation distribution of steel grade A according to Example 5;
11 is a graph showing the crystal orientation distribution of steel grade A according to Example 6;
12 is a graph showing crystal orientation distribution of steel grade A according to Example 7;
13 is a graph showing the crystal orientation distribution of steel grade B according to Example 8;
14 is a graph showing the crystal orientation distribution of steel grade C according to Example 9;
15 is a graph showing the crystal orientation distribution of steel grade D according to Example 10;
16 is a graph showing the crystal orientation distribution of steel grade E according to Example 10;
FIG. 17 is a graph showing a relationship between annealing plate surface average grain size (y) and plate thickness (x) of steel sheet A according to Example 11; FIG.
18 and 19 are graphs showing the crystal orientation distribution of steel grade A according to Example 12;
20 is a graph showing the crystal orientation distribution of steel grade F according to Example 13;
21 is a graph showing the crystal orientation distribution of steel grade A according to Example 14;
22 is a graph showing the crystal orientation distribution of steel grade A according to Example 15;
23 is a graph showing the crystal orientation distribution of steel grade A according to Example 16;
24 is a graph showing the crystal orientation distribution of steel grade G according to Example 17;
25 is a graph showing the crystal orientation distribution of steel grade H according to Example 18;
26 is a graph showing the crystal orientation distribution of steel class H according to Example 18.
FIG. 27 is a graph showing the relationship between the average grain size (y) and the plate thickness (x) of the annealing plate of steel type H according to Example 19; FIG.
28 is a graph showing the grain orientation distribution and the average grain size (y) of the steel grade H according to Example 20;

Hereinafter, a preferred embodiment of the (100) [0vw] non-oriented electrical steel sheet having excellent magnetic properties will be described with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation.

In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

In addition, the following embodiments are not intended to limit the scope of the present invention, but merely as exemplifications of the constituent elements set forth in the claims of the present invention, and are included in technical ideas throughout the specification of the present invention, Embodiments that include components replaceable as equivalents in the elements may be included within the scope of the present invention.

Judging from the solubility curves of AlN presented in W.C. Leslie (Trans. ASM vol. 46, 1954, pp 1470), Al deoxidized steels can be re-used in AlN in the steel sheet steels described below when reheating slabs above 1200 ° C. In addition, in 3% Si steel, N.G. Ainslie (JISI vol. 3, 1960, pp 341) and N.H. Judging from the solubility curve of MnS of Heo (ISIJ International vol. 51, 2011, pp 280), it is possible to reconstruct MnS in the component range steel plate described below when reheating a hot rolled sheet of 1320 ° C or higher.

The present invention adds S, the most important element for the production of a new (100) [0vw] non-oriented electrical steel sheet at 0.0001% to 0.035%, and Si and Mn, which are the main elements of the iron-based alloy, in the entire temperature range of the manufacturing process. Under the conditions of becoming a ferrite phase, the surface energy of the (100) grains by the surface segregated S is preferentially suppressed to be more than 0 to 0.20% by weight or less, and N is more than 0 to 0.0030% by weight. Hereinafter, P is suppressed to more than 0 and 0.2% by weight or less, and reheating the hot rolled sheet at 1370 ° C. or more is designed to enable re-use of MnS in the component range described later.

Accordingly, the component range of the slab used in the present invention is in a weight percent, such as by weight, more than 0: 0.005%, Si: 2-4%, Mn: 0.05% so as to constitute a ferrite phase in the temperature range over the entire manufacturing process At least 1.0%, S: 0.0001 to 0.035%, Al: more than 0 and 0.20% or less, P: more than 0 and 0.2% or less, N: more than 0 and 0.003% or less, and the remaining Fe and other unavoidable impurities. As a result, it is possible to easily and inexpensively manufacture a (100) [0vw] non-oriented electrical steel sheet having a thickness of 0.10 to 0.70 mm having excellent magnetic properties within the component range. In the addition amount of the alloying elements to be mixed, the increase in the resistivity is the largest Si and Mn is about half the effect of Si.

In one embodiment of the present invention, by weight% C: more than 0 0.005% or less, Si: 2-4%, Mn: 0.05% or more less than 1.0%, S: 0.0001-0.035%, Al: more than 0 0.20% or less, P: more than 0 and 0.2% or less, N: more than 0 and 0.003% or less, composed of the remaining Fe and other unavoidable impurities, and the hot-rolled, pickled and cold-rolled slabs of the composition consisting of ferrite phase in the entire temperature range In order to prevent (111) crystal growth due to surface oxidation of Al, Fe, Si, etc., the annealing plate is finally annealed in a reducing gas atmosphere, whereby the surface of the annealing plate is made of (100) [0vw] crystal orientation.

Further, according to one embodiment of the present invention, by weight% C: more than 0 and less than 0.005%, Si: 2 to 4%, Mn: 0.05% or more and less than 1.0%, S: 0.0001 to 0.035%, Al: more than 0 0.20 Crystal orientation in the final annealing plate containing not more than%, not less than 0, not more than 0.2%, not less than 0, not more than 0, not more than 0.003%, composed of the remaining Fe and other unavoidable impurities, and composed of a ferrite phase in the entire temperature range. Is (100) [0 vw], and at the same time, there is a relationship of y ≧ 2.2x + 0.1, or y ≥ 1.48x + 0.04 between the average grain size (y, mm) and the plate thickness (x, mm).

In addition, according to an embodiment of the present invention, by weight% C: more than 0 0.005% or less, Si: 2-4%, Mn: 0.05% or more less than 1.0%, S: 0.0001-0.035%, Al: more than 0 Reheat slab containing 0.20% or less, P: greater than 0 or less 0.2% or less, N: greater than 0 or less and 0.003% or less, composed of the remaining Fe and other unavoidable impurities, and exhibiting a ferrite phase structure in the temperature range of the entire manufacturing process. In order to make MnS which can be generated during hot rolling after rolling, the hot-rolled sheet is subjected to intermediate annealing at 950 ° C to 1370 ° C or omitted. The final annealing in the furnace to produce a (100) [0vw] non-oriented electrical steel sheet.

In addition, according to an embodiment of the present invention, the heat treatment atmosphere of the first stage annealing furnace and the second stage annealing furnace uses a reducing gas atmosphere to prevent (111) crystal growth due to surface oxidation of Al, Fe, Si, and the like. . At this time, in order to suppress (111) crystal growth as much as possible in the first stage of annealing and to activate the crystal growth of (100) as much as possible in the second stage annealing temperature higher than the first stage annealing temperature, the temperature of the first stage annealing furnace is 800 ° C. to 1100. The temperature of the two-stage annealing furnace is set at 1150 to 1370 degrees Celsius higher than the temperature of the one-stage annealing furnace.

Hereinafter, the reason for limiting the composition of the present invention will be described.

S: 0.0001 to 0.035 wt%

As described above, since selective crystal growth of the desired (100) [0vw] grains can occur when an adequate amount of surface segregated S is present, the surface energy of (110) during the heat treatment is best when the S content is completely removed. The low (110) grain orientation is finally obtained, not the (100) [0 vw] grain orientation, because only (110) grains grow while encroaching on other grains.

Thus, the substantial S content should be at least 0.0001% by weight or more so that S can surface segregate and change surface energy, and prevent the formation of MnS that impedes selective crystal growth of (100) [0vw] grains upon final annealing. In order to achieve this, S is preferably limited to 0.035% by weight or less.

More preferably, in consideration of the economics in the current steelmaking process, S is preferably limited to more than 0.008% by weight to 0.035% by weight or less.

C: more than 0 and less than 0.005%

In the conventional method for forming (100) [0vw] crystal orientation using austenite (γ) → ferrite (α) phase transformation accompanied by decarburization reaction during a long time vacuum heat treatment, C is required to include 0.02 to 0.07% of C in the steel sheet. .

In this case, due to the extremely slow decarburization reaction in a vacuum, a heat treatment time of several tens of hours is required to obtain a (100) [0vw] crystal orientation after the final annealing, and a batch type heat treatment suitable for a long heat treatment time is inevitable.

However, in the case of manufacturing a (100) [0vw] non-oriented electrical steel sheet according to an embodiment of the present invention, the conventional austenitic (γ) → ferrite (α) phase transformation using a long time oxidizing vacuum atmosphere heat treatment method is not used. , As shown in Table 1 of the following Examples using the composition showing the ferrite structure in the entire temperature range in the manufacturing process, in order to obtain a (100) [0vw] crystal orientation easily after the final annealing within a short time in a reducing gas atmosphere, The strong austenite stabilizing element C in the range is limited to more than 0 and 0.005% by weight or less.

Accordingly, in the case of manufacturing a (100) [0vw] non-oriented electrical steel sheet according to an embodiment of the present invention, a final annealing method of unwinding and winding the conventional (111) [uvw] non-oriented electrical steel sheet production method (Winding-rewinding) Because the method) can be used, mass production is possible within a short time, and manufacturing cost can be reduced due to productivity improvement.

On the other hand, as an inevitable addition of impurity elements, elements to be lowered if possible include Ti, B, Sn, Sb, Ca, Zr, Nb, V, Cu, and the like.

Si: 2.0-4.0 wt%

Si is added because it increases the specific resistance and lowers the eddy current loss during iron loss, and when added in excess of 4.0% by weight, the cold rolling is poor and fracture of the rolled plate occurs. Thus, the slab in the manufacturing process according to the embodiment of the present invention It is preferable to limit the content of the composition of the composition to between 2.0 wt% and 4.0 wt%, which is the minimum content of the ferrite structure in the entire temperature range.

Mn: 0.05 wt% or more but less than 1.0 wt%

Mn is an austenite stabilizing element that increases the specific resistance like Si to lower the eddy current loss during iron loss, but when Mn is added 1.0 wt% or more in electrical steel sheet containing 2 ~ 4 wt% Si, the austenitic fraction in the steel sheet is increased. Thus, the slab does not exhibit a ferrite structure in the entire temperature range in the manufacturing process.

Therefore, in order to obtain the non-oriented electrical steel sheet of the desired (100) [0vw] crystal orientation by using the manufacturing method of the present invention, the Mn content range is currently set so that the slab exhibits a ferrite structure in the temperature range of the entire manufacturing process. It is desirable to limit the content to 0.05% by weight or more and less than 1.0% by weight, which is the minimum content that can be lowered in the process.

Al: more than 0 and 0.2% by weight or less

Al is added to the existing (111) [uvw] non-oriented electrical steel sheet by 0.2 ~ 1.3% because it is an effective component to decrease the eddy current loss by increasing the specific resistance like Si.

However, since the object of the present invention is to produce (100) [0vw] non-oriented electrical steel sheet, when Al is added in excess of 0.2% in the composition of the present invention, a surface oxide layer by Al is formed upon annealing, and the surface oxide layer The H ₂ S reaction, which is a reaction between S segregated on the surface of the steel sheet directly below and hydrogen in a reducing atmosphere, does not occur smoothly due to the surface oxide layer, resulting in an increase in segregation concentration of S on the surface of the steel sheet directly below the surface oxide layer.

As a result, the surface energy of the (111) grains is minimized rather than the surface energy of the (100) grains. Therefore, as Al increases, selective grain growth of (111) grains is promoted rather than selective grain growth of (100) grains, so that the final grain orientation is shown in (100) [0vw] grain orientation as shown in FIGS. Since the crystal orientation is changed to the (111) [uvw] crystal orientation, the content of Al is preferably limited to more than 0 and 0.2 wt% or less in order to obtain the (100) [0vw] crystal orientation.

P: more than 0 and 0.2% by weight or less

P is added to increase the resistivity to lower the iron loss, but the result of FIG. 20 of Example 13 does not affect obtaining a full (100) [0vw] crystal orientation even when 0.1 wt% is added. However, when P is excessively added, cracking is more likely during cold rolling due to grain boundary embrittlement due to grain boundary segregation of P during the hot rolling process.

N: In order to prevent selective crystal growth inhibition of (100) [0vw] grains by the produced AlN, it is preferable to keep N as low as possible from 0 to 0.003% by weight or less.

Hereinafter, a method of manufacturing a (100) [0vw] non-oriented electrical steel sheet having excellent magnetic properties according to an embodiment of the present invention will be described.

Hot rolling does not adversely affect the crystal growth at the final annealing because the slab is heated to a high temperature of 1200 ° C. or higher and the finishing temperature in the hot rolling process is 900 ° C. or higher, since there is little precipitation of fine AlN and MnS in the hot rolled sheet. Do not. In addition, in the case where hot-rolled sheet annealing is performed with the same component or not, the magnetic properties at the same level can be obtained.

According to one embodiment of the present invention, the hot rolled plate may be prepared in the final plate thickness by cold rolling once as it is after pickling, and also by two cold rolling methods including intermediate annealing after one cold rolling.

At this time, the solubility temperature of 0.0001% S is 950 ℃ and the solubility temperature of 0.035% S is 1370 ℃, so that MnS that can be produced after hot rolling is dissolved in the temperature range of 950 ℃ ~ 1370 depending on the content of S. It is preferable that it is made of ℃.

As described above, the final annealing composed of one and two stages is required to be performed in a reducing gas atmosphere containing hydrogen and / or nitrogen to prevent (111) crystal growth due to surface oxidation of Al, Fe, Si, and the like. There is.

In addition, the first stage and the second stage annealing are divided into two stages in order to obtain stable (100) [0vw] crystal orientation, and the division should be divided into one stage annealing and two stage annealing. Connect passages between the furnaces to allow continuous annealing.

At this time, in order to suppress (111) crystal growth as much as possible in the first stage annealing and to activate the crystal growth of (100) as much as possible in the second stage annealing temperature higher than the first stage annealing temperature, the temperature and heat treatment time range of the first stage annealing furnace is It is set to 800-1100 degreeC, 10 second-600 second, and the temperature and heat processing time range of a two stage annealing furnace shall be 1150 degreeC-1370 degreeC, and 10 second-600 second.

If the heat treatment time is less than 10 seconds, the atomic migration time is insufficient, so that the alignment of the (100) texture is difficult, and if the heat treatment time exceeds 600 seconds, the heat treatment time is changed to the (111) texture. It is preferable to set it as 600 seconds.

The (100) [0vw] non-oriented electrical steel sheet having excellent magnetic properties according to an embodiment of the present invention is continuously manufactured by using a winding-rewinding method from the above hot rolling to final annealing. Can be.

On the other hand, the surface coating of the manufactured electrical steel sheet may be used as the coating method that is commonly used as needed.

Hereinafter, examples will be described.

Table 1 shows the various chemical compositions of the specimens to be used in the examples to be described later, with the remainder being made of Fe and other unavoidable impurities. The specimens each had a plate shape, and the plates were cast into ingots through a vacuum induction melting process, and the hot rolled 3 mm thick hot rolled sheet was heated according to the content of S after heating the ingot to 1200 ° C. In order to solidify the MnS that can be produced during the time of 950 ℃ ~ 1370 ℃ annealing treatment and not the case is divided into cold rolling after pickling to prepare a 0.10 ~ 0.70mm thick cold rolled steel sheet. At this time, the cold rolling rate was in the range of 77% to 97%.

In addition, the final annealing method for the cold-rolled steel sheet was selected not by vacuum, but by heat treatment method consisting of annealing ending at a time from 1150 ℃ to 1370 ℃ at a reducing gas atmosphere, one stage annealing and two stage annealing. In this case, in the case of the heat treatment consisting of one-stage annealing and two-stage annealing, the temperature and heat treatment time range of the first-stage annealing furnace is 800 ° C. to 1100 ° C. and 10 seconds to 600 seconds. It was set as 1150 degreeC-1370 degreeC, and 10 second-600 second. An etching-pit method and an optical microscope were used to determine the crystal orientation of the annealing plate.

River bell Ingredient (% by weight) C Si Mn P S Al N A 0.002 3.3 0.7 0.003 0.001 0.0008 0.002 B 0.002 2.1 0.1 0.003 0.001 0.0007 0.002 C 0.002 3.3 0.7 0.002 0.007 0.0008 0.002 D 0.002 2.1 0.1 0.003 0.001 0.2 0.002 E 0.002 0.1 0.1 0.002 0.002 1.5 0.002 F 0.002 3.3 0.7 0.1 0.001 0.0008 0.002 G 0.002 3.3 0.7 0.002 0.011 0.0005 0.002 H 0.002 3.3 0.7 0.002 0.035 0.0005 0.002

Example 1

After the annealing treatment of the hot rolled sheet formed as shown in Table 1 at 1050 ℃, pickling and cold rolling to prepare a cold rolled steel sheet having a thickness of 0.20mm, omitting one stage annealing for the cold rolled steel sheet for 600 seconds at 1300 ℃ Final annealing. Fig. 5 shows the result, and the crystal orientation does not represent 100% (100) [0vw], but 47% (100) [0vw] and 52% (111) [uvw].

[Example 2]

After the annealing treatment of the hot rolled sheet formed as shown in Table 1 at 1050 ℃, pickling and cold rolling to prepare a cold rolled steel sheet having a thickness of 0.20mm, the final annealing for the cold rolled steel sheet at 850 ℃ for 1 stage 540 seconds Thereafter, annealing was performed two times for 15 seconds at a higher temperature of 1300 ° C. FIG. 6 shows the results and shows a non-oriented electrical steel sheet structure composed of about 89% (100) [0 vw] and 11% (111) [uvw].

[Example 3]

After the annealing treatment of the hot rolled sheet formed as shown in Table 1 at 1050 ℃, pickling and cold rolling to prepare a cold rolled steel sheet having a thickness of 0.20mm, the final annealing for the cold rolled steel sheet at 850 ℃ for 1 stage 540 seconds Thereafter, annealing was carried out for two seconds at 60 ° C., which is higher than this. Figure 7 shows the results and shows the complete 100% (100) [0 vw] non-oriented electrical steel sheet structure. 8 shows the etch fit structure. It can be seen from the complete 100% (100) [0vw] crystal orientation that the etch fit type with the main orientation is (100) [012].

Example 4

After the annealing treatment of the hot rolled sheet formed as shown in Table 1 at 1050 ℃, pickling and cold rolling to prepare a cold rolled steel sheet having a thickness of 0.20mm, the final annealing for the cold rolled steel sheet is annealed for 1 second at 850 ℃ for 180 seconds Thereafter, annealing was performed for two seconds at 600 ° C., higher than this. FIG. 9 shows the results and again shows a complete 100% (100) [0vw] non-oriented electrical steel sheet structure having a main orientation of (100) [012].

[Example 5]

After the annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, pickling and cold rolling were performed to prepare a cold rolled steel sheet having a thickness of 0.20 mm, and the final annealing of the cold rolled steel sheet was performed at 850 ° C. for 540 seconds after one stage annealing. And annealing at 120 ° C. for 2 seconds at a higher temperature of 1300 ° C. FIG. 10 shows the results and shows a complete 100% (100) [0vw] non-oriented electrical steel sheet structure having a main orientation of (100) [012].

[Example 6]

After the annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, a cold rolled steel sheet having a thickness of 0.20 mm was prepared by pickling and cold rolling. The final annealing of the cold rolled steel sheet was performed after 1 stage annealing at 1100 ° C. for 10 seconds. , And annealing at 1150 ° C. for 600 seconds, which was higher than this. FIG. 11 shows the results and shows a complete 100% (100) [0vw] non-oriented electrical steel sheet structure having a main orientation of (100) [012].

[Example 7]

After the annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, pickling and cold rolling were performed to prepare a cold rolled steel sheet having a thickness of 0.20 mm, and the final annealing for the cold rolled steel sheet after one-stage annealing at 800 ° C. for 600 seconds. 2 stage annealing was performed at 1370 degreeC which is higher than this for 10 second. FIG. 12 shows the results, showing a complete 100% (100) [0vw] non-oriented electrical steel sheet structure having a main orientation of (100) [012].

[Example 8]

After the annealing treatment of the hot rolled sheet formed as shown in Table 1, the annealing treatment was omitted, and a cold rolled steel sheet having a thickness of 0.20 mm was prepared by pickling and cold rolling. After the final annealing of the cold rolled steel sheet at 850 ° C. for 540 seconds, And annealing at 120 ° C. for 2 seconds at a higher temperature of 1300 ° C. FIG. 13 shows the results and shows a complete 100% (100) [0vw] non-oriented electrical steel sheet structure having a main orientation of (100) [012].

[Example 9]

After the annealing treatment of the hot rolled sheet prepared as shown in Table 1 at 1230 ℃, pickling and cold rolling to prepare a cold rolled steel sheet having a thickness of 0.20mm, the final annealing for cold rolled steel sheet at 960 ℃ for one second 120 seconds Thereafter, annealing was performed for two hundred and twenty seconds at a higher temperature of 1300 ° C. FIG. 14 shows the results and again shows a complete 100% (100) [0vw] non-oriented electrical steel sheet structure having a main orientation of (100) [012].

[Example 10]

The annealing treatment of the hot rolled sheet formed as shown in D and E of Table 1 was omitted, followed by pickling and cold rolling to prepare a cold rolled steel sheet having a thickness of 0.20 mm, and the final annealing of the cold rolled steel sheet was performed at 850 ° C. for 540 seconds in one step. After annealing, annealing was carried out for two hundred and twenty seconds at 1300 ° C. 15 and 16 show the results. As Al is added, the crystal orientation of (111) [uvw] remains after the final annealing as Al is added, and the crystal orientation is 75% at 100% (100) [0 vw] as Al content is increased. It can be seen that% (100) [0vw] + 25% (111) [uvw] and 30% (100) [0vw] + 70% (111) [uvw].

[Example 11]

The annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, and a cold rolled steel sheet having a thickness of 0.10 mm to 0.70 mm was prepared by pickling and cold rolling. The final annealing of the cold rolled steel sheet was performed at 960 ° C. for 120 seconds for 1 second. However, after annealing, annealing was performed for 2 seconds at 120 ° C higher than this. A complete 100% (100) [0vw] crystal orientation could be obtained regardless of the thickness, and the relationship between the average grain size (y, mm) and the plate thickness (x, mm) is shown graphically in FIG.

At this time, the average grain size (y, mm) and the plate thickness (x, mm) of the surface of the annealing plate exhibiting a 100% (100) [0vw] crystal orientation showed a linear relationship of y = 2.2x + 0.1, S Was less than 0.007% by weight, all satisfied the relationship of y = 2.2x + 0.1.

[Example 12]

The annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, and a cold rolled steel sheet having a thickness of 0.25 mm and 0.35 mm was prepared by pickling and cold rolling. The final annealing of the cold rolled steel sheet was performed at 800 ° C. for 120 seconds. However, after annealing, annealing was performed two times for 60 seconds at a higher temperature of 1300 ° C.

18 and 19 show the grain orientation distribution and mean grain size (y) for them, showing a relationship of y <2.2x + 0.1 between the mean grain size (y) and the plate thickness (x) of the annealing plate surface. In this case, the crystal orientation does not represent 100% (100) [0 vw], but represents a significant amount of (111) [uvw] fraction regardless of thickness.

This result shows that due to improper one-stage annealing, the growth of (111) grains appearing at the initial stage of two-stage annealing at 1300 ° C. for 60 seconds becomes active, and for the remaining time, (100) grains grow while encroaching on (111) grains. This is because the (111) grains remain after the completion of the two-stage annealing.

Therefore, in order to obtain a complete 100% (100) [0vw] crystal orientation after 1 and 2 stage annealing, when S is less than 0.007% by weight, the average grain size (y) and the plate thickness (x) of the surface of the annealing plate are Heat treatment should be performed to show the relationship y ≥ 2.2x + 0.1.

In the case of Example 12, when the grain size (y) is one or more times larger than the annealing plate thickness (x), 50% or more of the (100) [0vw] crystal orientation was obtained.

[Example 13]

The annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, followed by pickling and cold rolling to prepare a cold rolled steel sheet having a thickness of 0.35 mm, and the final annealing for the cold rolled steel sheet after one stage annealing at 850 ° C. for 540 seconds. And annealing at 120 ° C. for 2 seconds at a higher temperature of 1300 ° C. 20 shows the results and shows a complete 100% (100) [0 vw] crystal orientation structure.

 Example 14

The hot rolled steel sheet annealing treatment, as shown in Table 1, was omitted, and a cold rolled steel sheet having a thickness of 0.20 mm was prepared by pickling and cold rolling. The first stage of the cold rolled steel was omitted, and the final annealing was performed at 1150 ° C. for 240 seconds. It was. Fig. 21 shows the result, and the crystal orientation does not represent perfect 100% (100) [0vw] but 54% (100) [0vw] and 46% (111) [uvw].

Example 15

The annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, and a cold rolled steel sheet having a thickness of 0.20 mm was prepared by pickling and cold rolling. The first stage of the cold rolled steel was omitted and 400 seconds at 1370 ° C. was omitted. Annealed. Fig. 22 shows the result, and the crystal orientation does not represent perfect 100% (100) [0vw] but 59% (100) [0vw] and 41% (111) [uvw].

[Example 16]

After the annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, pickling and cold rolling were performed to prepare a cold rolled steel sheet having a thickness of 0.20 mm, and the final annealing of the cold rolled steel sheet was performed at 750 ° C. for 1 second for 1000 seconds. , Two annealing at 1130 ° C. for 8 seconds. Fig. 23 shows the result and shows the structure of (111) [uvw] non-oriented electrical steel sheet whose main orientation is 85% or more.

Example 17

The hot rolled sheet formed as shown in Table 1 G was annealed at 1330 ° C., pickled and cold rolled to produce a 0.20 mm thick cold rolled steel sheet, and the final annealing for the cold rolled steel sheet was performed at 1020 ° C. for 30 seconds. Thereafter, annealing was performed for two hundred and twenty seconds at 1300 ° C. higher than this. Fig. 24 shows the result and shows the 100% (100) [0 vw] non-oriented electrical steel sheet structure.

[Example 18]

The hot rolled steel sheet formed as shown in Table 1 H or not was subjected to annealing at 1370 ° C., pickled and cold rolled to prepare a 0.20 mm thick cold rolled steel sheet, and the final annealing for the cold rolled steel sheet was performed at 1020 ° C. for 30 seconds. After one stage annealing, two stage annealing was performed for 120 seconds at a higher temperature of 1300 ° C. 25 and 26 show the results and show 100% (100) [0vw] non-oriented electrical steel sheet structure with or without annealing treatment.

[Example 19]

The annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, and a cold rolled steel sheet having a thickness of 0.10 mm to 0.70 mm was prepared by pickling and cold rolling. However, after annealing, annealing was performed two times for 90 seconds at a higher temperature of 1300 ° C. A complete 100% (100) [0vw] crystal orientation could be obtained regardless of the thickness, and the relationship between the average grain size (y, mm) and the plate thickness (x, mm) of the surface of the annealing plate was graphically shown in FIG. It was.

At this time, the average grain size (y, mm) and the plate thickness (x, mm) of the surface of the annealing plate exhibiting a perfect 100% (100) [0vw] crystal orientation showed a linear relationship of y = 1.48x + 0.04. In the case where S was 0.007 wt% or more, the relationship of y = 1.48x + 0.04 was satisfied.

[Example 20]

The annealing treatment of the hot rolled sheet formed as shown in Table 1 was omitted, followed by pickling and cold rolling to prepare a cold rolled steel sheet having a thickness of 0.35 mm. , Two annealing at 1300 ° C. for 10 seconds. FIG. 28 shows the grain orientation distribution and mean grain size (y) for them, showing a relationship of y <1.48x + 0.04 between the mean grain size (y) and the plate thickness (x) of the annealing plate surface. In this case, the crystal orientation did not represent a perfect 100% (100) [0 vw] but a considerable amount of (111) [uvw] fraction.

This result shows that due to inadequate one-stage annealing, growth of (111) grains appearing at the initial stage of two-stage annealing at 1300 ° C. for 10 seconds becomes active, and for the remaining time, (100) grains grow while encroaching on (111) grains. This is because the (111) grains remain after the completion of the two-stage annealing.

Therefore, in order to obtain a complete 100% (100) [0vw] crystal orientation after one-stage and two-stage annealing, when S is 0.007 wt% or more, the average grain size (y) and the plate thickness (x) of the surface of the annealing plate are Heat treatment should be performed to show the relationship y ≥ 1.48x + 0.04.

Claims (6)

By weight%, C: more than 0 and less than 0.005%, Si: 2 to 4%, Mn: 0.05% and more and less than 1.0%, S: 0.0001 to 0.035%, Al: more than 0 and 0.20% or less, P: more than 0 and 0.2% or less , N: greater than 0 and less than 0.003%, is composed of the remaining Fe and other unavoidable impurities, characterized by excellent magnetic properties, characterized in that the average grain size of the plate surface is equal to or greater than the plate thickness (100) [0vw] Non-oriented electrical steel sheet.
The method according to claim 1,
The average grain size y and the plate thickness x of the plate surface are
(100) [0vw] non-oriented electrical steel sheet having excellent magnetic properties, characterized in that when S is less than 0.007% by weight, y ≧ 2.2 × + 0.1 (unit: mm).
The method according to claim 1 or 2,
The average grain size y and the plate thickness x of the plate surface are
(100) [0vw] non-oriented electrical steel sheet having excellent magnetic properties, characterized in that when S is 0.007% by weight or more, y ≧ 1.48x + 0.04 (unit: mm).
The method according to claim 1,
Excellent magnetic properties, characterized in that the first stage annealing in the first stage annealing furnace of 800 ℃ ~ 1100 ℃, and the second stage annealing in two stage annealing furnace of 1150 ℃ 1370 ℃ higher than the temperature of the first stage annealing furnace (100) [0vw] Non-oriented electrical steel sheet.
The method of claim 4,
(100) [0vw] non-oriented electrical steel having excellent magnetic properties, characterized in that the heat treatment time in the first stage annealing furnace is 10 seconds to 600 seconds, and the heat treatment time in the second stage annealing furnace is 10 seconds to 600 seconds. .
The method according to claim 1,
The S (100) [0 vw] non-oriented electrical steel sheet having excellent magnetic properties, characterized in that it contains more than 0.008% ~ 0.035%.

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