JP2004315956A - High strength non-oriented electrical steel sheet with excellent magnetic property, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-oriented electrical steel sheet combining excellent magnetic properties and high strength. <P>SOLUTION: The steel sheet has a composition consisting of ≤0.02% C, ≤4.5% Si, ≤3.0% Mn, ≤3.0% Al, ≤0.50% P, ≤5.0% Ni, 0.2 to 4.0% Cu, and the balance Fe with inevitable impurities. Further, yield stress is made to a value not lower than CYS(MPa) represented by the equation: CYS=180+5600[%C]+95[%Si]+50[%Mn]+37[%Al]+435[%P]+25[%Ni]+22d<SP>-1/2</SP>, where d is the average grain size (mm) of crystal grains. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a non-oriented electrical steel sheet, particularly a typical example of a rotor of a high-speed rotation motor, suitable for parts subjected to large stress, high-strength and non-oriented electrical steel sheet having low iron loss characteristics and It relates to the manufacturing method.

  In recent years, with the development of motor drive systems, it has become possible to control the frequency of a drive power supply, and the number of motors that perform high-speed rotation at variable speed operation or commercial frequency is increasing. Such a motor that rotates at high speed requires a rotor that can withstand high-speed rotation. That is, since the centrifugal force acting on the rotating body increases in proportion to the radius of rotation and in proportion to the square of the rotating speed, the stress acting on the rotor may exceed 600 MPa in a medium or large-sized high-speed motor. Therefore, in such a high-speed rotation motor, the strength of the rotor needs to be high.

  In addition, in a magnet embedded DC inverter control motor in which permanent magnets are embedded in the rotor, which has increased from the viewpoint of improving motor efficiency in recent years, magnets tend to fly out of the rotor by centrifugal force. A large force is applied to the used electromagnetic steel sheet. For this reason, high strength is required for electrical steel sheets used for motors, especially rotors.

  Rotating devices such as motors and generators utilize electromagnetic phenomena, and therefore it is desirable that their materials have excellent magnetic properties, that is, low iron loss and high magnetic flux density. Normally, the rotor core is used by laminating non-oriented electrical steel sheets that have been stamped by pressing.If the rotor material cannot satisfy the above-mentioned mechanical strength in a high-speed rotation motor, a higher-strength cast steel rope or the like must be used. It is the present situation that does not get. However, since the cast rotor is an integral body, the eddy current loss due to high-frequency magnetic flux called ripple loss acting on the rotor is larger than that of a rotor having laminated electromagnetic steel sheets, which is a factor that lowers the motor efficiency. Accordingly, a magnetic steel sheet having excellent magnetic properties and high strength has been demanded as a material for a rotor.

In terms of metallurgy, three methods of solid solution strengthening, precipitation strengthening and grain refinement are known as means for increasing strength, and examples of application to electromagnetic steel sheets are also seen. For example, as a method using solid solution strengthening, Patent Document 1 discloses a method in which the Si content is increased to 3.5 to 7.0% and an element having a large solid solution strengthening ability is added. Patent Document 2 discloses that the content of Si is set to 2.0 to 3.5%, the content of Ni or both Ni and Mn is increased, and the recrystallization grain size is controlled by low-temperature annealing at 650 to 850 ° C. A method is disclosed. Further, as a method utilizing precipitation strengthening, Patent Literature 3 discloses a method in which a Si content is 2.0 to 4.0% and fine carbides and nitrides of Nb, Zr, Ti, and V are precipitated.
JP-A-60-238421 JP 62-256917 A JP-A-6-330255

By these methods, an electromagnetic steel sheet having a certain high strength can be obtained. However, a steel having a large amount of Si as described in Patent Literature 1 has a disadvantage that the cold rollability is remarkably reduced and stable industrial production becomes difficult. Further, the steel sheet obtained by this technique is magnetic flux density B ₅₀ has a problem that deteriorates significantly and 1.56～1.60T.

  In the method disclosed in Patent Document 2, it is necessary to suppress the growth of recrystallized grains by low-temperature annealing in order to increase the mechanical strength. Therefore, there is a problem that the magnetic properties, particularly the iron loss at several hundred Hz from a relatively low commercial frequency, are reduced. was there.

  On the other hand, the method described in Patent Literature 3 has a problem that the carbon loss is inferior because the carbon and the nitride themselves act as barriers for domain wall movement, and the carbon and the nitride hinder the crystal grain growth of the magnetic steel sheet.

  As described above, none of the conventional methods is satisfactory from the viewpoint of achieving both high strength and low iron loss in magnetic steel sheets that can be stably industrially produced.

  An object of the present invention is to propose a non-oriented electrical steel sheet having both good magnetic properties and high strength, and a manufacturing method capable of industrially stably producing this steel sheet.

The present inventors have conducted various studies focusing on the age hardening phenomenon of steel containing Cu in order to solve the above problems, and as a result, have established means for achieving both good iron loss and high strength. I came to. That is, contrary to the conventional knowledge that precipitates in steel contribute to high strength, but suppress domain wall movement and deteriorate iron loss (history loss), aging is performed by adding an appropriate amount of Cu to steel. By performing the treatment, it is possible to uniformly precipitate ultra-fine Cu having an average diameter of 20 nm or less, and the ultra-fine precipitate thus obtained is very effective for increasing the strength. It was newly found that iron loss (history loss) hardly deteriorated.
The present invention is based on the above findings.

That is, the gist configuration of the present invention is as follows.
(1) In mass%,
C: 0.02% or less,
Si: 4.5% or less,
Mn: 3.0% or less,
Al: 3.0% or less,
P: 0.50% or less,
Ni: 5.0% or less and
Cu: 0.2% or more and 4.0% or less, composed of the balance of Fe and inevitable impurities, and having a yield stress of not less than CYS (MPa) represented by the following formula, and having excellent magnetic properties. Strength non-oriented electrical steel sheet.
Record
CYS = 180 + 5600 [% C] +95 [% Si] +50 [% Mn] +37 [% Al]
+435 [% P] +25 [% Ni] + 22d ^-1/2
Here, d: average grain size of crystal grains (mm)

(2) In mass%,
C: 0.02% or less,
Si: 4.5% or less,
Mn: 3.0% or less,
Al: 3.0% or less,
P: 0.50% or less,
Ni: 5.0% or less and
Cu: 0.2% or more and 4.0% or less, the balance is composed of Fe and unavoidable impurities, and the steel has 0.2 to 2.0 vol% of Cu precipitates, and the average diameter of the Cu precipitates is 1 to 2.0%. High-strength non-oriented electrical steel sheet with excellent magnetic properties, characterized by having a thickness of 20 nm.

(3) In the above (1) or (2), as a component composition, one or more selected from Zr, V, Sb, Sn, Ge, B, Ca, a rare earth element, and Co, in mass% ,
0.1 to 3.0% for Zr and V, respectively
0.002-0.5% for Sb, Sn and Ge, respectively
0.001 to 0.01% for B, Ca and rare earth elements, and
0.2-5.0% for Co
A high-strength non-oriented electrical steel sheet with excellent magnetic properties characterized by containing

(4) In mass%,
C: 0.02% or less,
Si: 4.5% or less,
Mn: 3.0% or less,
Al: 3.0% or less,
P: 0.50% or less,
Ni: 5.0% or less and
Cu: hot rolled steel slab containing 0.2% or more and 4.0% or less, then cold rolled or warm rolled to the final thickness, and then heated to (Cu solid solution temperature + 10 ° C) or more After performing a finish annealing to cool from the Cu solid solution temperature to 400 ° C at a rate of 10 ° C / s or more, and then subjecting it to aging treatment at a temperature of 400 ° C or more and 650 ° C or less, Manufacturing method of excellent high strength non-oriented electrical steel sheet.

(5) In mass%,
C: 0.02% or less,
Si: 4.5% or less,
Mn: 3.0% or less,
Al: 3.0% or less,
P: 0.50% or less,
Ni: 5.0% or less and
Cu: 0.2% or more and 4.0% or less, and one or more kinds selected from Zr, V, Sb, Sn, Ge, B, Ca, a rare earth element and Co,
0.1 to 3.0% for Zr and V, respectively
0.002-0.5% for Sb, Sn and Ge, respectively
0.001 to 0.01% for B, Ca and rare earth elements, and
0.2-5.0% for Co
The steel slab contained in is subjected to hot rolling, cold rolling or warm rolling to the final thickness, and then heated to (Cu solid solution temperature + 10 ° C) or higher, and then to the Cu solid solution temperature. High-strength non-directional electromagnetic with excellent magnetic properties, which is subjected to finish annealing to cool at a rate of 10 ° C / s or more from 400 ° C to 400 ° C, and then to aging at a temperature of 400 ° C to 650 ° C. Steel plate manufacturing method.

  According to the present invention, it is possible to stably provide an electromagnetic steel sheet having excellent magnetic properties and high strength.

Next, the present invention will be described in detail for each component.
(Steel composition)
First, the component composition range and the reason for the limitation will be described. In this specification,% representing the steel composition means mass% unless otherwise specified.
C: 0.02% or less When the C content exceeds 0.02%, iron loss is remarkably deteriorated due to magnetic aging. Therefore, the content is limited to 0.02% or less.

Si: 4.5% or less
In addition to being useful as a deoxidizing agent, Si has a large effect of reducing iron loss of an electromagnetic steel sheet by increasing electric resistance. In addition, solid solution strengthening contributes to strength improvement. As a deoxidizing agent, the effect becomes remarkable at 0.05% or more. In order to reduce iron loss and strengthen solid solution, the content is 0.5%, preferably 1.2% or more. However, if the content exceeds 4.5%, the rollability of the steel sheet is greatly deteriorated, so the content is limited to 4.5% or less.

Mn: 3.0% or less
Mn is an element effective for improving hot brittleness in addition to an element effective for improving strength by solid solution strengthening, and is preferably contained at 0.05% or more. However, since excessive addition causes deterioration of iron loss, its content is limited to 3.0% or less.

Al: 3.0% or less
Al is effective as a deoxidizing agent, and is preferably contained at 0.5 ppm or more. However, excessive addition causes a reduction in rollability, so the amount is limited to 3.0% or less.

P: 0.50% or less P is extremely effective for increasing the strength because a large amount of solid solution strengthening ability can be obtained even with a relatively small amount of addition, and is preferably contained at 0.01% or more. On the other hand, excessive content causes embrittlement due to segregation, resulting in grain boundary cracking and reduction in rollability. Therefore, the content is limited to 0.50% or less.

Ni: 5.0% or less
Ni is an element effective for increasing the strength by solid solution strengthening, and is preferably contained at 0.1% or more. Because, when Ni is added together with Cu, it has the effect of suppressing the coarsening of Cu precipitates, especially in high Si steels where the growth of the aging precipitate phase of Cu precipitates is easily promoted, and the effect of increasing the aging precipitation hardening ability Is easy to obtain. However, if it exceeds 5.0%, the effect saturates and only increases the cost, so the upper limit is set to 5.0%.

Cu: 0.2% or more and 4.0% or less
By forming fine precipitates by aging treatment, Cu significantly increases the strength with almost no deterioration of iron loss (history loss). Here, unless the addition amount of Cu is 0.2% or more, a predetermined amount of Cu precipitates cannot be obtained in the aging treatment described later. Therefore, the addition amount of Cu is 0.2% or more. On the other hand, if the added amount of Cu exceeds 4.0%, the average size of the Cu precipitates exceeds 20 nm in the aging treatment described below, and the precipitates become coarse, the iron loss is increased and the strength increase is also reduced. Therefore, the content of Cu is in the range of 0.2% to 4.0%, preferably 0.5% to 2.0%.

  The other elements are Fe (iron) and unavoidable impurities. It is desirable that S and N as inevitable impurities are each 0.01% or less from the viewpoint of iron loss.

The basic composition of the non-oriented electrical steel sheet according to the present invention is as described above. In addition to the above components, Zr, V, Sb, Sn, Ge, B, Ca, rare earth elements known as elements for improving magnetic properties And Co can be added alone or in combination. However, the amount added should not be detrimental to the purpose of the present invention. In particular,
0.1 to 3.0% for Zr and V,
0.002 to 0.5% for Sb, Sn and Ge,
0.001 to 0.01% for B, Ca and rare earth elements,
0.2-5.0% for Co
It is.

(Structure of steel sheet, characteristic value)
In the non-oriented electrical steel sheet according to the present invention, Cu in the steel sheet is finely precipitated in the steel, that is, 0.2 to 2.0 vol% Cu precipitates in the steel, the average of the Cu precipitates It is important that the diameter is 1 to 20 nm.
First, if the amount of the Cu precipitate in the steel is less than 0.2 vol%, the precipitation density required for precipitation strengthening cannot be obtained, so that 0.2 vol% or more is required.
On the other hand, if the amount of the Cu precipitate exceeds 2.0 vol%, the probability that adjacent precipitates are united increases, and the average size of the precipitate becomes coarse, making it difficult to obtain a significant increase in strength. Do the following.

  In addition, the finer the Cu precipitate, the finer it contributes to the increase in strength. However, if the average diameter of the Cu precipitate in steel is less than 1 nm, the effect of increasing the strength is saturated and the measurement of the diameter of the Cu precipitate described later is performed. In this case, it is difficult to specify a small diameter of less than 1 nm, which may hinder the management of the product structure in such a small range. Therefore, the average diameter is set to 1 nm or more, particularly from the viewpoint of industrial production. On the other hand, when the average diameter of the Cu precipitate exceeds 20 nm, it does not contribute to the increase in strength and also deteriorates iron loss. Therefore, it is important that Cu be present as fine precipitates having an average diameter of 1 to 20 nm that contribute to high strength without deteriorating iron loss.

Here, the amount of Cu precipitates in the steel was determined in advance by measuring the thickness of a sample collected from a steel plate after aging treatment described later, and a scanning transmission electron microscope image (dark Field images were photographed in several fields, Cu precipitates were recognized by image processing, and the recognized Cu precipitates were derived by statistical processing.
In addition, the average diameter of the Cu precipitate, the Cu precipitate similarly recognized by image processing,
(a) calculating the sphere equivalent diameter from the average volume per Cu precipitate in the visual field,
(b) Obtain the sphere equivalent diameter of each Cu precipitate from each Cu precipitate volume and calculate the average value thereof,
(c) calculating the equivalent circle diameter from the average area per Cu precipitate in the field of view,
(d) calculating an equivalent circle diameter of each Cu precipitate from each Cu precipitate area and calculating an average value thereof.
The average diameter of the Cu precipitates is in the range of 1 to 20 nm, which means that the average diameter obtained by at least one of the above-described (a) to (d) measurement methods is 1 to 20 nm. In the range.

At this time, if the sample thickness of the observation region is too thin, the frequency of dropping of Cu precipitates increases, and if it is too thick, it becomes difficult to recognize precipitated particles in a scanning transmission electron microscope image. Preferably, it is in the range of 60 nm.
In general, the transmission electron microscope sample of Cu-containing steel tends to overestimate the amount of precipitation due to the influence of surface-deposited Cu particles, so it is preferable to use a sample whose surface has been cleaned with argon ions for observation. .
Incidentally, as shown in FIG. 1, as an example when a 1.8% Si-1.0% Cu-based steel sheet after aging treatment is observed in accordance with the above, particles floating white on a black background are precipitated by aging.

  In addition, the Cu precipitate in the present invention is, of course, intended for the precipitate of Cu, but when the precipitate is extremely fine, Cu may contain iron, including such a case This is called Cu precipitate.

  Although coarse Cu precipitates may be observed at the grain boundaries depending on the production conditions, in the present invention, it is important to define the Cu precipitates in the crystal grains. In other words, in order to impart the above-mentioned properties expected in the present invention to an electrical steel sheet, it is effective to strengthen its matrix, and it is important to realize fine precipitation of Cu contributing to this strengthening in crystal grains. It is.

By the way, in a steel having a Cu content of 0.20 to 4.0%, preferably 0.5 to 2.0%, for example, by aging annealing at 500 ° C. × 10 h, an average of about 5 nm of Cu precipitate can be finely precipitated in the steel. As a result, a strength increase of about 100 MPa can be obtained after aging. As a result, the yield stress YS (MPa) of the product is not less than CYS represented by the following equation.
Record
CYS = 180 + 5600 [% C] +95 [% Si] +50 [% Mn] +37 [% Al]
+435 [% P] +25 [% Ni] + 22d ^-1/2

In the above formula, the coefficient of the term of each element represents the amount of solid solution strengthening per 1% of each element. D is the average crystal grain size (diameter: mm) of the product, and the thickness cross section along the rolling direction is observed by an optical microscope on a sample etched with a nital etchant, etc. It is obtained as a circle equivalent diameter of crystal grains from the number of grains. The smaller the average crystal grain size d, the higher the strength, but the lower the core loss. Therefore, the crystal grain size d is adjusted according to the required strength and iron loss characteristics.
The appropriate crystal grain size depends on the required iron loss level, but is generally about 0.02 to 0.2 mm.

  In order to realize the increase in strength due to the above-mentioned aging without adversely affecting the magnetic properties, it is essential to control the precipitation state of Cu in addition to the above-mentioned component composition, in particular, optimizing the aging conditions and the like. It is important to manufacture according to the following conditions.

(Production method)
In order to produce a high-strength non-oriented electrical steel sheet excellent in iron loss according to the present invention, first, in a converter or an electric furnace, a steel melted to the above-described predetermined component is continuously cast or formed. A steel slab is formed by slab rolling after the ingot. The composition range of the steel slab may be the same as the composition range of the target product plate. Next, the obtained slab is hot-rolled, subjected to hot rolling slope annealing as necessary, and subjected to cold rolling or warm rolling two or more times with one or intermediate annealing sandwiched to a product thickness, and finished. Anneal and then aging. Further, at any stage after the final annealing, an insulating coating is applied and baked as required.

In the above-mentioned finish annealing, the Cu solid solution temperature is set to {Cu solid solution temperature (Ts) + 10 ° C} or more to dissolve Cu, and the Cu solid solution temperature is set to suppress the precipitation of Cu in the cooling process of finish annealing. It is carried out by cooling at a rate of 10 ° C./s or more from to 400 ° C. When the annealing temperature is lower than (Cu solid solution temperature + 10 ° C.), coarse Cu precipitates remain in the product, and the strength does not become high even by subsequent aging annealing. Further, even when the cooling rate is less than 10 ° C./s, Cu precipitates coarsely and does not become high in strength even after aging annealing. Although the upper limit of the finish annealing temperature is not particularly set, if it exceeds 1150 ° C., iron loss deterioration accompanying oxidation of the steel sheet surface increases, so it is preferable to set it to 1150 ° C. or less.
The Cu solid solution temperature (Ts)
Ts (° C) = 3351 / {3.279-log ₁₀ (Cu mass%)}-273
Required by

  The subsequent aging treatment is performed at a temperature of 400 ° C. to 650 ° C., preferably 450 ° C. to 600 ° C. That is, when the temperature is lower than 400 ° C., precipitation of fine Cu becomes insufficient, and high strength cannot be obtained. On the other hand, if the temperature exceeds 650 ° C., the Cu precipitates are coarsened, so that the iron loss is deteriorated and the amount of increase in strength is also reduced, so that an electrical steel sheet having a good strength-iron loss balance cannot be obtained. The appropriate aging time also depends on the processing temperature, but is preferably from 20 s to 1000 h. The aging treatment may be carried out at any time before the application and baking of the insulating film, after the baking, and after processing such as press punching.

  Steel having the component composition shown in Table 1 was melted in a converter and slab was formed by continuous casting. Next, the slab was formed into a hot-rolled sheet having a thickness of 2.2 mm by hot rolling. This hot-rolled sheet was cold-rolled into a cold-rolled sheet having a final thickness of 0.5 mm, and then subjected to finish annealing under the annealing conditions shown in Table 1. At that time, the cooling rate from the Cu solid solution temperature to 400 ° C. was 20 ° C./s. Thereafter, the finish annealed plate was subjected to an aging treatment at 500 ° C. and 10 hours, and then an insulating film was formed thereon to obtain a product plate. The composition of the product was the same as the slab composition shown in Table 1.

With respect to the product sheet thus obtained, the average crystal grain size d, the iron loss W _15/50 , and the yield stress YS were evaluated. The iron loss was measured by the Epstein test method. The yield stress YS was measured in the rolling direction of the product sheet and the direction perpendicular to the rolling direction, and the values were averaged.
The average crystal grain size d was obtained as an equivalent circle diameter by observing the product cross section with an optical microscope.

The evaluation of Cu precipitates was performed as follows by observation with a scanning transmission electron microscope. First, a sample for electron microscopy observation was collected as a flat plate parallel to the rolling surface from the center of the thickness of the product plate, thinned by electropolishing using a perchloric acid-methanol-based electrolytic solution, For cleaning, argon ion sputtering was performed for 5 minutes to prepare. Observation was performed in a scanning transmission mode in which an electron beam having a diameter of 1 nm or less was scanned in an observation visual field, and dark field images in which precipitates were easily recognized were obtained in three visual fields. In addition, if the observation region is too thin, the frequency of falling of the precipitated particles increases, and if the observation region is too thick, it becomes difficult to recognize the precipitated particles in a scanning transmission electron microscope image. Therefore, the thickness of the observation region is set in the range of 30 to 60 nm. Here, the sample thickness was estimated from the electron energy loss spectrum. For all the 400 nm x 400 nm dark field images thus obtained, the particles of the Cu precipitates are recognized by image processing, the number of Cu precipitates is determined, and the circle equivalent diameter of each Cu precipitate is determined from the area of each Cu precipitate. From the equivalent circle diameter of each Cu precipitate, the volume of each Cu precipitate was determined assuming that each Cu precipitate was a sphere, and the total volume thus determined was defined as the total Cu precipitate volume. . Next, from the total Cu precipitate volume and the total volume of the observation target, that is, the total volume of the volumes of each visual field (400 nm × 400 nm × thickness of the observation region), the precipitation amount (f) is calculated as a volume fraction, The equivalent sphere diameter of the precipitate was determined from the average precipitate volume obtained by dividing the total Cu precipitate volume by the number of Cu precipitates, and was evaluated as the average diameter (dp).
These evaluation results are also shown in Table 1.

As shown in Table 1, each of the compositions whose component compositions were controlled within the range of the present invention had high strength and excellent iron loss in the product sheet. In these invention examples, the precipitation amount f and average diameter dp of Cu precipitates, which are strengthening factors, are within the invention range.
On the other hand, in the conventional steel having a low Si content (Comparative Example: No. 1-10) and the conventional steel having a high Si content (Comparative Example: No. 1-11), although good iron loss is obtained, Low strength. In addition, steel containing excessive Cu (Comparative Example: No. 1-7) had poor iron loss and low strength.

  Steel having the component composition shown in Table 2 was melted by a converter and made into a slab by continuous casting. This slab is hot-rolled into a hot-rolled sheet having a thickness of 1.8 mm. The hot-rolled sheet is annealed at 800 ° C. for 5 h, and then subjected to a single cold-rolling process to obtain a 0.35 mm-thick cold-rolled sheet. And Further, this cold-rolled sheet was subjected to finish annealing under the conditions shown in Table 2, then an insulating film was formed, and an aging treatment shown in Table 2 was performed to obtain a product. The composition of the product plate was the same as the slab composition.

About the product plate thus obtained, as in the case of Example 1, the average crystal grain size d, the iron loss W _15/50 and the yield stress YS (MPa), the precipitation amount f of the Cu precipitate, and the average diameter dp ,evaluated.
As the evaluation results are shown in Table 2, when the steel composition, the finish annealing condition and the aging treatment condition were controlled within the range of the present invention, it was possible to obtain excellent iron loss and high strength in the product sheet. .

  However, in the conventional steel to which Cu is not added (Comparative Example: No. 2-11), excellent iron loss can be obtained, but high strength cannot be obtained. When the finish annealing temperature is too low (Comparative Example: No. 2-1), and when the finish annealing cooling rate is too slow (Comparative Example: No. 2-4), not only iron loss is deteriorated, but also High strength cannot be obtained. Further, when the aging temperature is too low (Comparative Example: No. 2-5), high strength cannot be obtained, and when the aging temperature is too high (Comparative Example: No. 2-10), iron The loss deteriorated, and high strength could not be obtained.

It is a figure which shows the scanning transmission electron microscope image of the steel plate after 1.8% Si-1.0% Cu aging treatment.

Claims (5)

In mass%,
C: 0.02% or less,
Si: 4.5% or less,
Mn: 3.0% or less,
Al: 3.0% or less,
P: 0.50% or less,
Ni: 5.0% or less and
Cu: 0.2% or more and 4.0% or less, composed of the balance of Fe and inevitable impurities, and having a yield stress of not less than CYS (MPa) represented by the following formula, and having excellent magnetic properties. Strength non-oriented electrical steel sheet.
Record
CYS = 180 + 5600 [% C] +95 [% Si] +50 [% Mn] +37 [% Al]
+435 [% P] +25 [% Ni] + 22d ^-1/2
Here, d: average grain size of crystal grains (mm) In mass%,
C: 0.02% or less,
Si: 4.5% or less,
Mn: 3.0% or less,
Al: 3.0% or less,
P: 0.50% or less,
Ni: 5.0% or less and
Cu: 0.2% or more and 4.0% or less, the balance is composed of Fe and unavoidable impurities, and the steel has 0.2 to 2.0 vol% of Cu precipitates, and the average diameter of the Cu precipitates is 1 to 2.0%. High-strength non-oriented electrical steel sheet with excellent magnetic properties, characterized by having a thickness of 20 nm. 3. The method according to claim 1, wherein one or more components selected from Zr, V, Sb, Sn, Ge, B, Ca, a rare earth element and Co are further contained as a component composition in mass%.
0.1 to 3.0% for Zr and V, respectively
0.002-0.5% for Sb, Sn and Ge, respectively
0.001 to 0.01% for B, Ca and rare earth elements, and
0.2-5.0% for Co
A high-strength non-oriented electrical steel sheet with excellent magnetic properties characterized by containing In mass%,
C: 0.02% or less,
Si: 4.5% or less,
Mn: 3.0% or less,
Al: 3.0% or less,
P: 0.50% or less,
Ni: 5.0% or less and
Cu: hot rolled steel slab containing 0.2% or more and 4.0% or less, then cold rolled or warm rolled to the final thickness, and then heated to (Cu solid solution temperature + 10 ° C) or more After performing a finish annealing to cool from the Cu solid solution temperature to 400 ° C at a rate of 10 ° C / s or more, and then subjecting it to aging treatment at a temperature of 400 ° C or more and 650 ° C or less, Manufacturing method of excellent high strength non-oriented electrical steel sheet. In mass%,
C: 0.02% or less,
Si: 4.5% or less,
Mn: 3.0% or less,
Al: 3.0% or less,
P: 0.50% or less,
Ni: 5.0% or less and
Cu: 0.2% or more and 4.0% or less, and one or more kinds selected from Zr, V, Sb, Sn, Ge, B, Ca, a rare earth element and Co,
0.1 to 3.0% for Zr and V, respectively
0.002-0.5% for Sb, Sn and Ge, respectively
0.001 to 0.01% for B, Ca and rare earth elements, and
0.2-5.0% for Co
The steel slab contained in is subjected to hot rolling, cold rolling or warm rolling to a final thickness, and then heated to (Cu solid solution temperature + 10 ° C) or higher, and then to the Cu solid solution temperature. High strength non-directional with excellent magnetic properties characterized by subjecting to finish annealing of cooling from 10 to 400 ° C at a rate of 10 ° C / s or more and then aging at a temperature of 400 to 650 ° C Manufacturing method of electrical steel sheet.

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