JP4469269B2 - Electrical steel sheet with excellent high-frequency magnetic properties and manufacturing method thereof - Google Patents

Description

  In the present invention, an electromagnetic steel sheet having a specific component further contains Cu and is subjected to an appropriate process treatment so that almost all of the Cu in the steel is present as solute Cu. The present invention provides a steel sheet, particularly a non-oriented electrical steel sheet. The electrical steel sheet obtained by the present invention is suitable for use in a high-speed rotating machine that transmits a high-frequency magnetic field through the steel sheet, a reactor, or the like.

  Conventionally, laminated magnetic steel sheets have been used for rotor and stator materials that are motor parts. Recently, not only high-speed rotation of the motor but also the complicated motor structure has led to the transmission of high-frequency magnetic flux through the steel sheet, and high-frequency magnetic properties, especially iron loss, have become a problem. .

  The iron loss of a steel sheet is generally divided into hysteresis loss and eddy current loss. Since hysteresis loss is proportional to the first power of frequency, eddy current loss is proportional to the second power of frequency. In the high frequency region, eddy current loss occupies most of the iron loss, and it is important how to suppress iron loss due to eddy current.

  For this purpose, it is well known that it is effective to increase the electrical resistance of a steel sheet, and generally steel containing a high concentration of Si, Al, Cr, etc. is used, and several proposals have been made. . For example, in Patent Document 1 and Patent Document 2, it is proposed to use a slab having a high Si content and further containing one or more solid solution strengthening components such as Mn, Ni, Mo, and Cr. However, there is room for improvement such as deterioration of castability, reduction in productivity due to frequent occurrence of sheet breakage during rolling, and reduction in yield. Moreover, when these components are contained in a large amount, there is a problem that the magnetic flux density is greatly reduced.

  Further, Patent Documents 3 and 4 disclose technologies related to electrical steel sheets containing a large amount of Cu, but due to the Cu phase precipitated in the steel, the reduction of eddy current loss cannot be said to be sufficient. There was room for improvement in applications where properties are a problem.

JP-A-1-162748 JP-A-61-84360 JP 2004-84053 A JP 2004-99926 A

  As described above, many proposals have been made for electrical steel sheets containing a large amount of alloying elements, but the actual situation is that they have not yet been industrially stable while ensuring the necessary magnetic properties. It is.

  An object of the present invention is to provide an electrical steel sheet that has a good magnetic flux density, is particularly excellent in high-frequency iron loss, and can be stably manufactured without greatly degrading castability, cold rolling property, and the like.

The present invention has been made to solve the above-mentioned problems, and by adding an appropriate heat treatment to an electromagnetic steel sheet containing Cu, the majority of the added Cu is contained as solute Cu, and a conventional alloy is obtained. An electrical steel sheet having excellent high-frequency magnetic properties is obtained without deteriorating magnetic properties or manufacturability associated with element addition. The summary is as follows.
(1) A large amount of Cu is added so as not to be seen conventionally.
(2) Suppresses the formation of the austenite phase in the high temperature region.
(3) A large amount of Cu is dissolved by performing high temperature heat treatment in the ferrite region.
(4) Cooling is controlled so that Cu that becomes supersaturated does not precipitate during cooling.
As a result, the added Cu exists as a solid solution Cu even in the final product, exhibits an effect of suppressing eddy current loss that is unthinkable in the past, can obtain a good high-frequency iron loss, and also deteriorates the magnetic flux density It is possible to suppress the influence of.
Specifically, the above effects are (1) mass%, C: 0.06% or less, Si: 1.5-6.5%, Mn: 0.05-3.0%, P: 0.00. 30% or less, S or Se: 0.040% or less, Al: 2.50% or less, Cu: 2.0 to 30.0%, N: 0.0400% or less, the balance Fe and inevitable impurities The ferrite single phase in the temperature range from room temperature to 1150 ° C., or in mass%, 980−400 × C + 50 × Si-30 × Mn + 400 × P + 100 × Al-20 × Cu-15 × Ni-10 × Cr An electrical steel sheet that satisfies> 900 and does not contain a metal phase made of Cu having a diameter of 0.010 μm or more inside the steel material.
(2) By mass%, Nb: 8% or less, Ni: 15.0% or less, Cr: 15.0% or less, Ce: 0.5% or less The electrical steel sheet according to (1), which is characterized.
(3) Of the steel sheets described in (1) or (2), in comparison with a steel sheet having the same steel component other than Cu, Cu: 0.1%, and the same crystal grain size, iron loss W10 / 400 it characterized in that 0.80 times or less electrical steel plate.
(4) Among the steel sheets according to any one of (1) to (3), the steel components other than Cu are substantially the same, and Cu: 0.1% and the crystal grain size is the same. in comparison to, you wherein the tensile strength is 2.0 times or less electrical steel plate.
(5) In the electrical steel sheet according to any one of (1) to (4), the number density of the metal phase mainly composed of Cu having a diameter of 0.02 μm or less inside the steel material before and after heat treatment at 450 ° C. for 30 minutes is (Magnetic number after the heat treatment) − (density number before the heat treatment) is 20 pieces / μm ³ or more.
(6) In the electrical steel sheet according to any one of (1) to (5), the tensile strength before and after heat treatment at 450 ° C. for 30 minutes is (tensile strength after heat treatment) − (tensile strength before heat treatment) ) Is 100 MPa or more.
(7) In the process of manufacturing the steel sheet according to any one of (1) to (6), the final heat treatment after cold rolling is held for 5 seconds or more in a temperature range of 800 ° C. or higher , and after the holding A method for producing an electrical steel sheet, wherein the cooling step is cooled to 300 ° C. or lower at a cooling rate of 40 ° C./second or higher .
(8) (7) Symbol in the manufacturing method of the electrical steel sheet of the mounting, the electrical steel sheet characterized by a heat treatment such as austenite phase is not generated in the steel material even at the maximum temperature in the final heat treatment after cold rolling Production method.
(9) In the said cooling process, 700-400 degreeC residence time shall be 5 second or less, The manufacturing method of the electrical steel sheet as described in (8) characterized by the above-mentioned.
(10) A method for producing an electrical steel sheet, which is not retained in a temperature range exceeding 400 ° C. for 30 seconds or more after the heat treatment according to any one of (7) to (9).

  According to the present invention, most of the contained Cu is present as solid solution Cu in the electromagnetic steel sheet, and thus a stable production method without any problems of productivity due to addition of solid solution elements other than Cu. Thus, it is possible to provide an electromagnetic steel sheet having excellent high-frequency magnetic characteristics.

  First, the component composition of the electrical steel sheet according to the present invention will be described.

  Since C deteriorates the magnetic characteristics, it is set to 0.06% or less. It is an effective element from the viewpoint of increasing strength, particularly increasing yield stress, improving warm strength, creep strength, and warm fatigue properties. Further, it effectively works for texture improvement, suppresses the development of {111} orientation which is undesirable for magnetism, and has the effect of promoting the development of preferred {110}, {100}, {114} and other orientations. From this viewpoint, it is preferably 0.04% or less, more preferably 0.0031 to 0.0301%, further preferably 0.0051 to 0.0221%, more preferably 0.0071 to 0.0181%, and still more preferably. Is 0.0081 to 0.0151%. Within the scope of the present invention, it is possible to suppress magnetic aging to such an extent that it does not pose a significant problem due to thermal history such as slow cooling in the temperature range of 400 ° C. or lower and low temperature maintenance.

  On the other hand, particularly when the requirements for magnetic aging are very strict, C is contained from the viewpoint of deoxidation efficiency until the slab stage, and C is reduced to 0.0040% or less by decarburization annealing after forming the coil. It is also possible to reduce. In this case, from the viewpoint of production cost, it is advantageous to reduce the amount of C by degassing equipment at the molten steel stage, and if it is 0.0020% or less, the effect of suppressing magnetic aging is remarkable and the strength is increased. When non-metal precipitates such as carbides are not used, the content is more preferably 0.0015% or less, and further preferably 0.0010% or less.

  Si increases the specific resistance of steel, reduces eddy currents, lowers iron loss, increases tensile strength, suppresses the formation of austenite phase at high temperature in the steel of the present invention, stabilizes the ferrite phase even at high temperature, and dissolves Cu Is effective to make the effect of reducing eddy current loss due to the effect remarkable, but the effect is small when the addition amount is less than 1.5%. Further, if the Si content is increased, not only the magnetic properties are not deteriorated, but particularly, it is possible to increase the strength while reducing the iron loss. Since the effect of reducing the eddy current loss due to the steel tends to be weak, steel containing Si is preferably 2.1% or more, more preferably 2.6% or more. Further, if it exceeds 6.5%, the steel is embrittled and further the magnetic flux density of the product is lowered, so that it is 6.5% or less, preferably 5.0% or less. In order to further reduce the fear of embrittlement, it is preferably 4.5% or less, and if it is 4.0% or less, there is a balance with the amount of other elements, but the steel of the present invention containing a large amount of Cu in a solid solution state. Then, there is almost no need to consider the embrittlement.

  Mn may be positively added to increase the strength of the steel, but is not particularly required for this purpose in the steel of the present invention that utilizes a fine metal phase as the main means for increasing the strength. It is added for the purpose of reducing iron loss by increasing specific resistance or coarsening sulfides and promoting grain growth, but excessive addition not only lowers magnetic flux density but also generates austenite phase at high temperature. Since it promotes, it is made 0.05 to 3.0%. Preferably, it is 0.5% to 1.2%.

  P is an element having a remarkable effect of increasing the tensile strength, but like the above Mn, the steel of the present invention does not need to be added for this purpose. Rather, it contributes to the stabilization of the ferrite phase at high temperatures, but it makes the steel extremely brittle, so that it cannot be contained in such a large amount that it becomes a main element for stabilizing the ferrite phase in the steel of the present invention. If it exceeds 0.30%, the embrittlement becomes severe and it becomes difficult to perform hot rolling and cold rolling on an industrial scale, so the upper limit is made 0.30%.

  S is easy to combine with Cu, which is an essential element in the steel of the present invention, and forms Cu sulfide, which may lower the solid solution Cu that is important in the present invention, so care must be taken when it is contained in a large amount. . Depending on the heat treatment conditions, it is possible to actively form fine Cu sulfide to increase the strength. The produced sulfide may deteriorate the magnetic properties, particularly the iron loss. Particularly in the case of a non-oriented electrical steel sheet, the content of S is preferably low, and is limited to 0.040% or less. Preferably it is 0.020% or less, More preferably, it is 0.010% or less. Se also has almost the same effect as S.

  Al is usually added as a deoxidizing agent, but it is also possible to suppress the addition of Al and deoxidize with Si. In particular, in the case of non-oriented electrical steel sheets, Si deoxidized steel having an Al content of about 0.005% or less has an effect of reducing iron loss because AlN is not generated. In the steel of the present invention, rather than the viewpoints of these deoxidation and nitride formation, it is positively added as solute Al in order to stabilize the ferrite phase at high temperature and to suppress eddy current loss by increasing electric resistance. Further, it also has an effect of promoting a remarkable reduction effect of eddy current loss due to solute Cu, which is a feature of the present invention, and like Si, it is preferably added positively, preferably 0.3% More preferably, it is 0.6% or more, more preferably 1.1% or more, further preferably 1.6% or more, and further preferably 2.1% or more. However, if it exceeds 2.50%, castability and embrittlement become problems, so the content is made 2.50% or less.

  Cu is an essential element in the present invention. By being present as solid solution Cu in the steel sheet, the range for expressing good high frequency characteristics is limited to 2.0 to 30.0%. When the Cu content is low, the effect of reducing eddy current loss is reduced. On the other hand, if the Cu content is too high, it becomes difficult to suppress the formation of a metal phase mainly composed of Cu, and not only the effect of reducing eddy current loss is reduced, but also a relatively coarse Cu metal phase is generated. In addition to significantly increasing the hysteresis loss, there is also a concern that the steel sheet will be cracked and flawed during hot rolling.

  The Cu content is preferably 2.1% or more, more preferably 2.6% or more, still more preferably 3.1% or more, still more preferably 3.6% or more, more preferably 4.1% or more, More preferably, it is 4.6% or more. The upper limit is preferably 20.0%, more preferably 15 in consideration of the addition cost of Cu itself and the addition cost of Ni added for the purpose of suppressing surface flaws (Cu baldness) during hot rolling caused by Cu. 0.0%, more preferably 12.0%, still more preferably 10.0%. In addition, if Cu added in high Si steel like this invention steel is a solid solution state, it will not embrittle steel and deteriorate cold-rollability like Si and Al, but rather by Si etc. It also has a preferable effect of suppressing embrittlement, and does not significantly deteriorate the magnetic flux density unlike Cr described later. Even if it is contained in a relatively large amount, the harm is small.

  N, like C, degrades the magnetic properties, so it is set to 0.0400% or less. In the case of Si deoxidized steel with an Al content of about 0.005% or less, in addition to increasing the strength like C, in particular, increasing yield stress, improving warm strength and creep strength, improving warm fatigue properties, It is an effective element from the viewpoint of improving the structure. From this viewpoint, preferably 0.0031 to 0.0301%, more preferably 0.0051 to 0.0221%, more preferably 0.0071 to 0.0181%, and still more preferably 0.0081 to 0.0151%. It is. However, when Al is about 0.010% or more, if a large amount of N is contained, fine AlN is formed and the magnetic properties are remarkably deteriorated. In Al deoxidized steel, it should be 0.0040% or less, and is preferably as low as possible in the steel of the present invention which does not expect an increase in strength due to nitride. The effect of suppressing characteristic deterioration is remarkable, more preferably 0.0022%, and still more preferably 0.0015% or less.

  Most of the elements other than the above used for increasing the electrical resistance in the conventional high alloy electrical steel sheets are not only problematic in addition cost and embrittlement, but also have an adverse effect on the magnetic flux density. Then there is no need to add it. In the case of intentionally adding, one or more of Nb, Ti, B, Ni, and Cr are added in consideration of cost increase and deterioration of magnetic characteristics, and the amount added is Nb: 8% or less, preferably 0.02% or less, Ti: 1.0% or less, preferably 0.010% or less, B: 0.010% or less, Ni: 15.0% or less, Cr: 15% or less, preferably 10.0% The following is assumed. In particular, Ni is known to be effective in preventing surface roughness (Cu hege) during hot rolling with Cu, which is an essential element in the steel of the present invention, and can be actively added for this purpose. It is.

  B is segregated at the grain boundary and has the effect of suppressing embrittlement due to the P grain boundary segregation. However, embrittlement is not a particular problem in the steel of the present invention as in the conventional high alloy electrical steel sheet. The addition for this purpose is not critical. Rather, it is added for the purpose of improving the magnetic flux density due to the influence of the solid solution B on the texture. If it exceeds 0.010%, the material is significantly brittle, so the upper limit is made 0.010%.

  Nb and Ti depend on the amount of C, N and S contained, but a large amount of fine precipitates such as carbides, nitrides or sulfides are formed in the steel sheet, and the iron loss is remarkably deteriorated. In order to promote the development of the {111} texture after annealing and lower the magnetic flux density, it is not necessary to add the steel according to the present invention. For this reason, the upper limit is Nb 8% or less, preferably 0.02% or less, and Ti 1.0% or less, preferably 0.010%. In both cases, it is more preferably 0.0050% or less, and even more preferably 0.0030% or less, and a good iron loss can be obtained.

  Ni is known to be effective in preventing surface roughness (Cu hege) at the time of hot rolling with Cu, which is an essential element in the steel of the present invention, and can also be positively added for this purpose. In addition, it is an element that is often used in high alloy electrical steel sheets because it has relatively small adverse effects such as embrittlement and is effective in reducing eddy current loss. For the purpose of preventing Cu scab, about 1/8 to 1/2 of the amount of Cu is added as a guide. However, a steel sheet that uses a Cu metal phase and has a high strength like the steel of the present invention exhibits a remarkable eddy current loss reduction effect that is not seen in the past by incorporating Ni in a composite. The cause of this is not clear, but the influence of the positions occupied by the solid solution Cu and solid solution Ni on the Fe crystal lattice and the formation of a regular lattice related to some Ni and Cu are expected. Moreover, although it is effective for improvement of corrosion resistance, the upper limit is preferably set to 15%, more preferably 10% in consideration of the adverse effect on the addition cost and magnetic properties.

  In general, Cr is an element added to improve corrosion resistance and magnetic properties in a high frequency range, but in the present invention, these roles are sufficiently exhibited by other elements such as Cu and Ni. There is no need to add it for this purpose. Rather, it is added to control the stability of the ferrite phase at a high temperature, but in the steel of the present invention, the magnetic flux density is significantly reduced by the addition, and it is rather a harmful element. Moreover, since the effect of reducing eddy current loss due to the solid solution Cu, which is characteristic in the present invention, appears remarkably in the low Cr steel, it is preferably not added unless there is any necessity. The reason for this is not clear, but the solid solution Cu effect in the present invention is remarkable due to the interaction phenomenon with other elements including Cr in addition to the above-mentioned Si, Al and Ni. it is conceivable that. Considering the addition cost, the upper limit is 15%, preferably 8.0%, more preferably 4.9%, more preferably 2.9%, more preferably 1.9%, more preferably 0.9%, and still more preferably Is preferably 0.4%.

  Moreover, about the other trace element, in addition to the quantity contained inevitably from an ore or a scrap, even if it adds for various purposes, the effect of this invention is not impaired at all. The inevitable content of these trace elements is usually about 0.005% or less for each element, but can be added to about 0.01% or more for various purposes. Also in this case, in consideration of cost and magnetic characteristics, one or more of Bi, Mo, W, Sn, Sb, Mg, Ca, Ce, La, and Co can be contained in a total amount of 0.5% or less.

The above-mentioned component characteristic is basically to increase the amount of the solid solution element, but it is necessary to make a component system that particularly increases the amount of the solid solution Cu. In addition, the effect of reducing eddy current loss and the embrittlement effect when the amount of dissolved Cu is increased are not only due to the amount of dissolved elements, but also have an interactive effect as described above. In consideration of the above, it is defined in the preferable component range as described above. Furthermore, since the steel plate targeted by the present invention is premised on the final heat treatment for recrystallization and grain growth, solid solution Cu is formed by the formation of precipitates containing Cu during this heat treatment. It is necessary to use a component that takes into account the change in quantity. In particular, the transformation of the steel matrix during the heat treatment not only greatly changes the solubility of Cu, but also the preferred texture disappears for the magnetic flux density. It should be avoided. The steel of the present invention is a ferrite single phase in the temperature range from room temperature to 1150 ° C.
980-400 × C + 50 × Si-30 × Mn + 400 × P + 100 × Al-20 × Cu-15 × Ni-10 × Cr> 900
It is characterized by satisfying. Outside this range, undesired transformation occurs during the heat treatment, increasing the possibility of impairing the effects of the present invention.

The characteristics of the present invention can be clearly shown by comparison with characteristics of general materials. The object to be compared is a steel plate having substantially the same steel components other than Cu, Cu: 0.1%, and the equivalent crystal grain size. In comparison with this, the iron loss W _10/400 is _0.00 . It is characterized by being 80 times or less. More preferred invention steel is 0.70 times or less, further preferred invention steel is 0.60 times or less, further preferred invention steel is 0.50 times or less, further preferred invention steel is 0.40 times or less, and further preferred invention steel is 0. .30 times or less.

  Similarly, the tensile strength is 2.0 times or less. Generally, as the amount of solid solution element increases, the strength increases due to solid solution strengthening, and when the amount of solid solution is large as in the present invention, the increase in strength is significant depending on the element. Solid solution Cu in Si steel does not harden the material so much. The more preferable invention steel is 1.7 times or less, and the still more preferable invention steel is 1.5 times or less. If the amount of solid solution Cu increases, the strength of the steel of the present invention will increase, but it is not preferable that the strength increase is small, but usually compared to Si, Cr, etc. used as solid solution elements, The increase in strength is small, and embrittlement is also suppressed.

The characteristics of the steel of the present invention can also be described by structural or characteristic changes when a specific heat treatment is performed. As a systematic change, remarkable precipitation of a metallic Cu phase due to the solid dissolution of excess Cu in the steel of the present invention is observed. In terms of characteristics, a significant increase in strength is observed with the precipitation of the metallic Cu phase. Further, although not particularly described in the present invention, it is accompanied by an increase in iron loss, particularly eddy current loss. Specifically, in the steel of the present invention, the number density of the metal phase mainly composed of Cu having a diameter of 0.02 μm or less within the steel material increases to 20 pieces / μm ³ or more by heat treatment at 450 ° C. for 30 minutes, or tensile strength Increases by 100 MPa or more. It should be noted that, as described above, such heat treatment significantly increases eddy current loss and degrades the high-frequency magnetic properties that are the object of the present invention. For example, as in the component analysis, the determination is made for determination of the invented steel.

  The steel containing the above components is melted in a converter in the same manner as a normal electromagnetic steel sheet, is made into a slab by continuous casting, and then manufactured by processes such as hot rolling, hot rolled sheet annealing, cold rolling, and finish annealing. The In addition to these steps, the formation of an insulating film and a decarburization step do not impair the effects of the present invention. Moreover, there is no problem even if it is manufactured not by a normal process but by a process such as a thin slab or a continuous casting process in which the production of a ribbon by the rapid solidification method or the hot rolling process is omitted.

  In order to contain a large amount of solute Cu characteristic in the present invention, it is effective to pass through the following thermal history. In the final heat treatment in the process of manufacturing the product plate, usually recrystallization annealing after cold rolling, it is held at a temperature range of 800 ° C. or more for 5 seconds or more, and even at the highest temperature reached in this heat treatment, austenite is contained in the steel material. The setting is such that no phase is generated. Preferably, it is 900 ° C. or higher, more preferably 1000 ° C. or higher, more preferably 1050 ° C. or higher, and the time is preferably 10 seconds or longer, more preferably 30 seconds or longer, more preferably 60 seconds or longer. The temperature and time at which sufficient dissolution of Cu takes into account the content is sufficient to obtain the characteristic effects of the present invention. However, it goes without saying that it is necessary to control the crystal grain size, which has a great influence on the magnetic properties.

  It is well known that a crystal grain size that is too fine or too coarse can degrade the magnetic properties, and that there is an optimum grain size for use conditions. Moreover, it is necessary to set the maximum attainable temperature in a temperature range where the austenite phase is not generated. If the amount is small, the adverse effect on characteristics is small, but annealing is preferably performed in a complete ferrite phase. Since this temperature mainly depends also on the steel component, a specific temperature cannot be described. However, the above-mentioned formula 1 serves as a temporary guide, and those skilled in the art who have knowledge about general metallurgy can be used. An appropriate temperature range can be set without any difficulty by a general heat treatment and microstructure observation experiment, or a thermodynamic calculation that has been developed in recent years.

  The cooling rate in the heat treatment process is also an important control factor. The reason for this is that Cu that has been sufficiently solutioned by holding at a high temperature is supersaturated during cooling, and depending on the cooling rate, may precipitate as a metallic Cu phase, which may reduce the effects of the present invention. . In the present invention, the preferable condition is that the cooling step after holding for 5 seconds or more in a temperature range of 800 ° C. or more is cooled to 300 ° C. or less at a cooling rate of 40 ° C./second or more. For the purpose of the present invention, the cooling rate has never been exceeded. However, if the cooling rate is too rapid, the characteristics may be deteriorated due to thermal distortion or the like. The temperature is preferably 60 ° C./second or more, more preferably 80 ° C./second or more, and further preferably 100 ° C./second or more.

  In particular, in the present invention, attention should be paid to the cooling in the temperature range where the precipitation of the metallic Cu phase occurs, and the residence time of 700 to 400 ° C. is important. This is because when the temperature is 700 ° C. or higher, the degree of supersaturation of Cu is small and precipitation is unlikely to occur, and when the temperature is 400 ° C. or lower, the diffusion of Cu is suppressed and precipitation is difficult to occur. If the time is 5 seconds or less, preferably 3 seconds or less, more preferably 2 seconds or less, precipitation of the metal Cu phase can be suppressed, and a sufficient amount of solid solution Cu can be ensured to obtain the effects of the invention. .

  And it is preferable not to hold | maintain for 30 second or more in the temperature range over 400 degreeC after this heat processing. This is because such a heat treatment promotes the precipitation of the metallic Cu phase and increases the eddy current loss.

  By passing through the above components and processes, the characteristic eddy current loss reduction effect by a large amount of solute Cu is efficiently expressed, and a high Cu electrical steel sheet is manufactured without substantially impairing castability and rollability. Can do. On the other hand, in the case of manufacturing with ordinary components and heat treatment conditions that are not conscious of maintaining the amount of solid solution Cu, a small portion of the added Cu exists as a metal Cu phase or Cu sulfide having a small effect of reducing eddy current loss. In addition, embrittlement is remarkable and normal production becomes difficult.

The present invention is characterized in that the metallic Cu phase does not exist in the steel material, but this can be confirmed by fixing with a diffraction pattern such as an electron microscope or an attached X-ray analyzer. Of course, it can be confirmed by other methods such as chemical analysis. In the present invention, the metal phase mainly composed of Cu has a diameter of 0.010 μm or more. The reason is that if it is too fine, less than 0.010 μm, it is difficult to identify the metal Cu phase that is the subject of the present invention even with the current highest precision analytical instrument. Moreover, no matter what treatment is performed, in the steel according to the present invention containing a large amount of Cu, precipitates containing some Cu are locally present, so that the metal Cu phase is completely excluded. This is because it is impossible. The present invention is limited to electrical steel sheets that contain a significant amount of Cu and that are clearly hardened or formed with a large amount of metallic Cu phase by the substantial heat treatment described in the present invention. Needless to say, this is a large amount of solute Cu.

  The effect of the present invention can be applied to a non-oriented or directional electrical steel sheet because it does not depend on the manufacturing process, regardless of the presence and type of the surface coating usually formed on the surface of the electrical steel sheet.

  The use is not particularly limited, and it is applicable to all uses where high-frequency magnetic characteristics are required, such as a rotor and a stator of a motor used in home appliances or automobiles, and the like.

  Further, although there is no direct relationship with the effect of the present invention, the iron loss measured by the electromagnetic steel sheet can be separated into hysteresis loss and eddy current loss by the following method. The iron loss depends on the frequency of the magnetic field at the time of measurement, and the relationship is known for hysteresis loss and eddy current loss. Therefore, if the iron loss measured at two different frequencies is known, the relationship between iron loss and frequency Separation is possible. This method is also called a “dual frequency method”, and generally, iron loss separation is performed by such treatment, and the characteristics of the electrical steel sheet are studied in detail.

The steel which shows a component in Table 1 was made into the slab of thickness 250mm, and the product board was manufactured on the conditions of Table 1,2. The magnetic flux density B ₁₀ and the iron loss W _10/400 were measured by a 55 mm square SST test. For the magnetic properties, the average value in the rolling direction of the coil, the 45 ° direction and the direction perpendicular thereto was obtained from the following equation.
X = (X ₀ + 2 × X ₄₅ + X ₉₀ ) / 4
Here, X ₀ , X ₄₅ , and X ₉₀ are characteristics of the coil rolling direction, 45 ° direction, and its perpendicular direction.

  As is apparent from the results shown in Table 2, the sample produced under the conditions of the present invention has good rolling properties in the cold rolling process and excellent magnetic properties. It has been confirmed that the good iron loss in the steel of the present invention is mainly due to the reduction of eddy current loss.

  As described above, according to the present invention, it is possible to suppress the embrittlement, make a high alloy component with low eddy current loss without causing problems such as cold rolling, and stably stabilize the electrical steel sheet having excellent high-frequency magnetic properties. Can be manufactured.

Claims (10)

In mass%, C: 0.06% or less, Si: 1.5 to 6.5%, Mn: 0.05 to 3.0%, P: 0.30% or less, S or Se: 0.040% Hereinafter, Al: 2.50% or less, Cu: 2.0 to 30.0%, N: 0.0400% or less, consisting of Fe and unavoidable impurities, ferrite in the temperature range from room temperature to 1150 ° C Single phase or in mass%,
980-400 × C + 50 × Si-30 × Mn + 400 × P + 100 × Al-20 × Cu
−15 × Ni-10 × Cr> 900
The electrical steel sheet is characterized by not containing a metal phase made of Cu having a diameter of 0.010 μm or more in the steel material. Further, it is characterized by containing one or more of Nb: 8% or less, Ni: 15.0% or less, Cr: 15.0% or less , and Ce: 0.5% or less. The electrical steel sheet according to claim 1. The steel loss W10 / 400 of the steel plate according to claim 1 or 2 in which the steel components other than Cu are the same, and Cu: 0.1% and the crystal grain size is the same. it characterized in that it is 80 times less electrical steel plate. Among the steel plates according to any one of claims 1 to 3, in comparison with a steel plate having the same steel component other than Cu and Cu: 0.1% and the same crystal grain size, the tensile strength is you wherein electrical steel plate that 2.0 times or less. The electrical steel sheet according to any one of claims 1 to 4, wherein the number density of the metal phase mainly composed of Cu having a diameter of 0.02 µm or less inside the steel material before and after heat treatment at 450 ° C for 30 minutes is (after the heat treatment). Density number) − (density number before the heat treatment) is 20 pieces / μm ³ or more. The electrical steel sheet according to any one of claims 1 to 5, wherein the tensile strength before and after heat treatment at 450 ° C for 30 minutes is (tensile strength after the heat treatment)-(tensile strength before the heat treatment) is 100 MPa or more . electromagnetic steel sheet characterized by Rukoto Oh. In the process of manufacturing the steel sheet according to any one of claims 1 to 6, the final heat treatment after cold rolling is held for 5 seconds or more in a temperature range of 800 ° C or higher , and a cooling step after holding is performed. A method for producing an electrical steel sheet, wherein the steel sheet is cooled to 300 ° C or lower at a cooling rate of ° C / second or higher . The method for manufacturing an electrical steel sheet according to claim 7 , wherein the heat treatment is performed so that an austenite phase is not generated in the steel material even at the highest ultimate temperature in the final heat treatment after the cold rolling . The method for manufacturing an electrical steel sheet according to claim 8 , wherein the residence time at 700 to 400 ° C is set to 5 seconds or less in the cooling step. A method for producing an electrical steel sheet, wherein the steel sheet is not held in a temperature range exceeding 400 ° C for 30 seconds or longer after the heat treatment according to any one of claims 7 to 9 .