JP4341386B2 - Non-oriented electrical steel sheet and manufacturing method thereof - Google Patents

Description

  The present invention relates to a non-oriented electrical steel sheet, particularly a non-oriented electrical steel sheet having a characteristic of high strength and low iron loss, which is suitable for a part subjected to a large stress, such as a rotor of a high-speed rotary motor. It relates to the manufacturing method.

  In recent years, with the development of motor drive systems, it is possible to control the frequency of the drive power supply, and the number of motors that perform variable speed operation and high-speed rotation above the commercial frequency is increasing. In such a motor that performs high-speed rotation, a rotor that can withstand high-speed rotation is required. That is, since the centrifugal force acting on the rotating body is proportional to the radius of rotation and increases in proportion to the square of the rotational speed, the stress acting on the rotor may exceed 600 MPa in medium and large high-speed motors. Therefore, in such a high-speed rotary motor, it is necessary that the strength of the rotor is high.

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

  Since rotating devices such as motors and generators use electromagnetic phenomena, it is desirable that the material has 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 out of the stamp. However, if the rotor material does not satisfy the above-mentioned mechanical strength in a high-speed rotary motor, it is necessary to use a caster made of higher-strength cast steel. It is the present condition that we do not get. However, since the casting made of cast iron is an integral object, the eddy current loss due to the high-frequency magnetic flux called ripple loss acting on the rotor is larger than that of the rotor laminated with electromagnetic steel sheets, which causes a reduction in motor efficiency. Therefore, there is a demand for a magnetic steel sheet having excellent magnetic properties and high strength as a rotor material.

In metallurgy, three methods of solid solution strengthening, precipitation strengthening, and crystal grain refinement are known as means for increasing strength, and examples applied to electrical steel sheets are also seen. For example, as a method utilizing solid solution strengthening, Patent Document 1 discloses a method of adding an element having a large solid solution strengthening capability after increasing the Si content to 3.5 to 7.0%. Further, in Patent Document 2, the recrystallized grain size is controlled by setting the Si content to 2.0 to 3.5%, increasing the content of Ni or both Ni and Mn, and manufacturing by low temperature annealing at 650 to 850 ° C. A method is disclosed. Further, as a method of utilizing precipitation strengthening, Patent Document 3 discloses a method of precipitating fine carbides and nitrides of Nb, Zr, Ti, and V with a Si content of 2.0 to 4.0%.
JP-A-60-238421 JP 62-256917 A JP-A-6-330255

By these methods, an electrical steel sheet having a certain degree of strength can be obtained. However, the steel having a large amount of Si as described in Patent Document 1 has a disadvantage that the cold rolling property is remarkably lowered and stable industrial production becomes difficult. Furthermore, the steel plate obtained by this technique has a problem that the magnetic flux density B ₅₀ is significantly reduced to 1.56 to 1.60 T.

  In the method in Patent Document 2, since it is necessary to suppress recrystallized grain growth by low-temperature annealing in order to increase mechanical strength, there is a problem that iron loss at several hundred Hz from a commercial frequency having a relatively low frequency is lowered. was there.

  On the other hand, the method described in Patent Document 3 has a problem that iron loss is inferior because charcoal and nitride itself serve as a barrier for domain wall movement and charcoal and nitride hinder crystal grain growth of the electromagnetic 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 an electromagnetic steel sheet that can be stably industrially produced.

  An object of the present invention is to propose a non-oriented electrical steel sheet that achieves both good magnetic properties and high strength and a manufacturing method that enables industrially stable production of this steel sheet.

In order to solve the above-mentioned problems, the inventors have made various studies focusing on the age hardening phenomenon of Cu-containing steel, and as a result, established means for achieving both good iron loss and high strength. I arrived. In other words, contrary to the conventional knowledge that precipitates in steel contribute to high strength and suppress the domain wall motion to deteriorate iron loss (history loss), an appropriate amount of Cu is added to the steel to age. By performing the treatment, it is possible to uniformly precipitate ultrafine Cu having an average diameter of 20 nm or less, and the ultrafine precipitate obtained in this way is very effective for increasing the strength. It was newly found that iron loss (history loss) hardly deteriorates.
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% to 4.0% inclusive, composed of the remaining Fe and inevitable impurities, and having 0.2 to 2.0 vol% Cu precipitates in the steel, the average diameter of the Cu precipitates being 1 to 20 nm (provided that the average diameter of unless a 0.02 [mu] m) non-oriented electrical steel sheet you being a.
(2) The non-oriented electrical steel sheet according to (1), wherein the yield stress is CYS (MPa) or more represented by the following formula.
Record
CYS = 180 + 5600 [% C] + 95 [% Si] + 50 [% Mn] + 37 [% Al]
+435 [% P] +25 [% Ni] + 22d ^-1/2
Where d: average grain size (mm) of crystal grains

(3) In the above (1) or (2), as a component composition, one or more selected from Zr, V, Sb, Sn, Ge, B, Ca, rare earth elements and Co are added in mass%. ,
For Zr and V, 0.1 to 3.0%,
0.002 to 0.5% for Sb, Sn and Ge,
0.001 to 0.01% for B, Ca and rare earth elements, respectively
0.2 to 5.0% for Co
Non-oriented electrical steel sheet you characterized by containing at.

(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: 0.2% or more and 4.0% or less, consisting of the remaining Fe and inevitable impurities, the steel slab is hot-rolled and then cold-rolled or warm-rolled to the final thickness. Then, after heating to (Cu solid solution temperature + 10 ° C) or higher, finish annealing is performed to cool from the Cu solid solution temperature to 400 ° C at a rate of 10 ° C / s or higher, and then to a temperature of 400 ° C or higher and 650 ° C or lower. method for producing a non-oriented electrical steel sheet you characterized by applying aging treatment Te.

(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% to 4.0%, and one or more selected from Zr, V, Sb, Sn, Ge, B, Ca, rare earth elements and Co,
For Zr and V, 0.1 to 3.0%,
0.002 to 0.5% for Sb, Sn and Ge,
0.001 to 0.01% for B, Ca and rare earth elements, respectively
0.2 to 5.0% for Co
The steel slab, which is composed of the remaining Fe and the inevitable impurities, is subjected to hot rolling, followed by cold rolling or warm rolling to obtain the final thickness, and then (Cu solid solution temperature) After heating to + 10 ℃) or higher, finish annealing is performed to cool from the Cu solid solution temperature to 400 ℃ at a rate of 10 ℃ / s or more, and then an aging treatment is performed at a temperature of 400 ℃ to 650 ℃. method for producing a non-oriented electrical steel sheet shall be the.

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

Next, the present invention will be described in detail for each constituent requirement.
(Component composition of steel sheet)
First, the component composition range and the reason for limitation will be described. In the present specification, “%” representing a steel composition means “% by mass” unless otherwise specified.
C: 0.02% or less If the C content exceeds 0.02%, the iron loss deteriorates significantly due to magnetic aging, so it is limited to 0.02% or less.

Si: 4.5% or less
In addition to being useful as a deoxidizer, Si has a great effect of reducing the iron loss of the electrical steel sheet by increasing the electrical resistance. Furthermore, it contributes to strength improvement by solid solution strengthening. As a deoxidizer, the effect becomes remarkable at 0.05% or more. For reducing iron loss and strengthening solid solution, it is contained at 0.5%, preferably 1.2% or more. However, if it exceeds 4.5%, the rollability of the steel sheet deteriorates severely, so its 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 being an element effective for improving strength by solid solution strengthening, and is preferably contained at 0.05% or more. However, excessive addition causes deterioration of iron loss, so its content is limited to 3.0% or less.

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

P: 0.50% or less P is extremely effective for increasing the strength because a significant solid solution strengthening ability can be obtained even when added in a relatively small amount, and is preferably contained at 0.01% or more. On the other hand, an excessive content causes embrittlement due to segregation and causes intergranular cracking and a decrease in rollability, so 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. This is because, when Ni is added together with Cu, it is effective in suppressing the coarsening of Cu precipitates and enhancing the age precipitation hardening ability, especially in high-Si steels where the growth of the aging precipitation phase of Cu precipitates is easy to promote. It is because it becomes easy to obtain. However, if it exceeds 5.0%, the effect will be saturated and only the cost will be increased, so the upper limit is set to 5.0%.

Cu: 0.2% to 4.0%
By forming fine precipitates by aging treatment, Cu brings about a significant increase in strength with almost no deterioration of iron loss (history loss). Here, unless a Cu addition amount of 0.2% or more is ensured, a predetermined amount of Cu precipitates cannot be obtained in the aging treatment described later, so the Cu addition amount is 0.2% or more. On the other hand, if the amount of Cu exceeds 4.0%, the average diameter of Cu precipitates becomes larger than 20 nm in the aging treatment described later, and the deterioration of iron loss increases and the strength increase margin also decreases. Therefore, the Cu content is in the range of 0.2% to 4.0%, preferably 0.5% to 2.0%.

  In addition to the above elements, they are Fe (iron) and inevitable impurities. S and N as inevitable impurities are each preferably 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 are known. And Co can be added alone or in combination. However, the amount added should be such that the object of the present invention is not impaired. In particular,
About 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 to 5.0% for Co
It is.

(Structure and characteristic values of steel sheet)
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, the steel has 0.2 to 2.0 vol% of Cu precipitates, and the average of the Cu precipitates. It is important that the diameter is 1 to 20 nm.
First, if the amount of Cu precipitates in the steel is less than 0.2 vol%, the precipitation density required for precipitation strengthening cannot be obtained, so 0.2 vol% or more is necessary.
On the other hand, if the amount of Cu precipitates exceeds 2.0 vol%, the probability that adjacent precipitates will coalesce increases, and the average size of the precipitates becomes coarse and it is difficult to obtain a significant increase in strength, so 2.0 vol% Below.

  The finer the Cu precipitates, the higher the strength. However, if the average diameter of the Cu precipitates in the steel is less than 1 nm, the effect of increasing the strength is saturated and the Cu precipitate diameter is measured later. In this case, it is difficult to specify a minute diameter of less than 1 nm, and there are cases in which the product structure is managed in such a minute range. Therefore, from the viewpoint of industrial production, the average diameter is 1 nm or more. On the other hand, if the average diameter of the Cu precipitate exceeds 20 nm, it will not contribute to the increase in strength and the iron loss will be deteriorated. 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 is determined in advance by measuring the thickness of a sample collected from a steel sheet after aging treatment, which will be described later, and a scanning transmission electron microscope image (darkness) of the sample in an area of about 400 nm × 400 nm. Several fields of view) were taken, Cu precipitates were recognized by image processing, and the recognized Cu precipitates were statistically processed.
In addition, the average diameter of Cu precipitates is the same for Cu precipitates recognized by image processing.
(a) Calculate the equivalent sphere diameter from the average volume per Cu precipitate in the field of view.
(b) Find the equivalent sphere diameter of each Cu precipitate from each Cu precipitate volume, calculate the average value,
(c) Calculate the equivalent circle diameter from the average area per Cu precipitate in the field of view,
(d) The equivalent circle diameter of each Cu precipitate can be determined from the area of each Cu precipitate, and the average value can be calculated by any of the methods.
And that the average diameter of Cu precipitates is in the range of 1 to 20 nm means that the average diameter obtained by at least one of the above-described measurement methods (a) to (d) is 1 to 20 nm. Means in the range of

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

  The Cu precipitates in the present invention are of course intended for Cu precipitates, but when the precipitates become extremely fine, Cu may contain iron, including such cases. This is called Cu precipitate.

  Depending on the production conditions, coarse Cu precipitates may be observed at the grain boundaries, but in the present invention, it is important to define the Cu precipitates in the crystal grains. That is, in order to impart the above-mentioned characteristics expected in the present invention to an electrical steel sheet, it is effective to strengthen its matrix, and it is important to realize Cu fine precipitation that contributes to this strengthening in the crystal grains. It is.

Now, in steel with 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 precipitates can be 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 formula.
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. Further, d is the average crystal grain size (diameter: mm) of the product, and a specimen obtained by etching a plate thickness section along the rolling direction with a nital etchant is observed with an optical microscope. It is calculated | required as a circle equivalent diameter of a crystal grain from the number of grains. The smaller the average grain size d, the higher the strength, but the iron loss deteriorates. Therefore, the crystal grain size d is adjusted according to the required strength and iron loss characteristics.
The appropriate crystal grain size is generally about 0.02 to 0.2 mm, although it depends on the required iron loss level.

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

(Production method)
In order to produce a high-strength non-oriented electrical steel sheet having excellent iron loss according to the present invention, first, a steel melted in the above-mentioned predetermined components is continuously cast or manufactured in a converter or an electric furnace. A steel slab is formed by rolling after 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 hill annealing as necessary, and subjected to cold rolling or warm rolling twice or more sandwiching one or intermediate annealing to obtain a product thickness. Annealing and then aging treatment. Furthermore, at any stage after finish annealing, an insulating coating is applied and baked as necessary.

In the above finish annealing, in order to dissolve Cu, the annealing temperature is set to {Cu solid solution temperature (Ts) + 10 ° C} or more, and the Cu solid solution temperature is used to suppress Cu precipitation in the cooling process of finish annealing. It is performed by cooling at a rate of 10 ° C / s or more from 1 to 400 ° C. When the annealing temperature is lower than (Cu solid solution temperature + 10 ° C), coarse Cu precipitates remain in the product and do not become high strength even by subsequent aging annealing. Even when the cooling rate is less than 10 ° C./s, Cu precipitates coarsely, and does not become high strength even by subsequent aging annealing. The upper limit of the finish annealing temperature is not particularly set, but 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) is
Ts (° C.) = 3351 / {3.279-log ₁₀ (Cu mass%)} − 273
It is calculated 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., the precipitation of fine Cu becomes insufficient and high strength cannot be obtained. On the other hand, when the temperature exceeds 650 ° C., the Cu precipitates become coarse, so that the iron loss is deteriorated and the amount of increase in strength is also reduced. An appropriate aging time depends on the treatment temperature, but is preferably 20 s or more and 1000 h or less. The aging treatment may be performed at any timing before or after the insulating film is applied and baked, after baking, or after processing such as press punching.

  Steel having the component composition shown in Table 1 was melted in a converter and made into a slab by continuous casting. Next, this slab was formed into a hot-rolled sheet having a thickness of 2.2 mm by hot rolling. This hot-rolled sheet was made into a cold-rolled sheet having a final sheet thickness of 0.5 mm by cold rolling, 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 set to 20 ° C./s. Thereafter, the finish annealed plate was subjected to an aging treatment at 500 ° C. and 10 hours, and then an insulating coating was applied to obtain a product plate. The product composition was the same as the slab composition shown in Table 1.

The product plate thus obtained was evaluated for average crystal grain size d, iron loss W _15/50 , and yield stress YS. The iron loss was measured by the Epstein test method. The yield stress YS was determined by measuring the rolling direction of the product plate and the direction perpendicular thereto, and averaging the values.
The average crystal grain size d was determined as an equivalent circle diameter by optical microscope observation of the product cross section.

Moreover, evaluation of Cu precipitate was performed as follows by scanning transmission electron microscope observation. First, a sample for electron microscope observation was collected as a flat plate parallel to the rolling surface from the center of the thickness of the product plate, and after thinning by electrolytic polishing using a perchloric acid-methanol electrolyte, For cleaning, sputtering with argon ions was performed for 5 minutes. Observation was performed in a scanning transmission mode in which an electron beam having a diameter of 1 nm or less was scanned in the observation field, and dark field images in which precipitates were easily recognized were obtained for each of three fields. If the observation region is too thin, the frequency of dropping of the precipitated particles is increased. If the observation region is too thick, it is difficult to recognize the precipitated particles in the 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 of the 400 nm × 400 nm dark field images obtained in this manner, particle recognition of Cu precipitates was performed by image processing, the number of Cu precipitates was determined, and the equivalent circle diameter of each Cu precipitate was determined from each Cu precipitate area. From the equivalent circle diameter of each Cu precipitate, the volume of each Cu precipitate was calculated assuming that each Cu precipitate was a sphere, and the total volume thus obtained was defined as the total Cu precipitate volume. . Next, from this total Cu precipitate volume and the total volume of the observation object, that is, the total volume of each visual field (400 nm × 400 nm × the thickness of the observation region), the precipitation amount (f) is calculated as a volume fraction, From the average precipitate volume obtained by dividing the total Cu precipitate volume by the number of Cu precipitates, the equivalent sphere diameter of the precipitate was determined and evaluated as the average diameter (dp).
These evaluation results are also shown in Table 1.

As shown in Table 1, all the components whose composition was controlled within the range of the present invention had high strength and excellent iron loss in the product plate. In these invention examples, the precipitation amount f and average diameter dp of Cu precipitates, which are strengthening factors, are within the scope of the invention.
On the other hand, in the low Si component-based conventional steel (Comparative Example: No. 1-10) and the high Si component-based conventional steel (Comparative Example: No. 1-11), although good iron loss is obtained, The strength is low. Moreover, 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, and hot rolled sheet is subjected to hot rolled sheet annealing at 800 ° C. × 5 h, and then cold rolled with a thickness of 0.35 mm by a single cold rolling method. It was. Furthermore, this cold-rolled sheet was subjected to finish annealing under the conditions shown in Table 2, and then an insulating coating was formed, and an aging treatment shown in Table 2 was performed to obtain a product. The product plate had the same composition as the slab composition.

With respect to the product plate thus obtained, as in Example 1, the average crystal grain size d, the iron loss W _15/50 and the yield stress YS (MPa), and the precipitation amount f and the average diameter dp of the Cu precipitates ,evaluated.
As the evaluation results are listed in Table 2, the steel composition, finish annealing conditions and aging treatment conditions controlled within the scope of the present invention were able to obtain excellent iron loss and high strength in the product plate. .

  However, in the conventional steel to which Cu is not added (Comparative Example: No. 2-11), although excellent iron loss can be obtained, high strength cannot be obtained. Further, when the finish annealing temperature is too low (Comparative Example: No. 2-1) and the finish annealing cooling rate is too slow (Comparative Example: No. 2-4), not only the iron loss is deteriorated, High strength cannot be obtained. Furthermore, 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 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 an aging treatment of 1.8% Si-1.0% Cu type | system | group.

Claims (5)

% By 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% to 4.0% inclusive, composed of the remaining Fe and inevitable impurities, and having 0.2 to 2.0 vol% Cu precipitates in the steel, the average diameter of the Cu precipitates being 1 to 20 nm (provided that the average diameter of unless a 0.02 [mu] m) non-oriented electrical steel sheet you being a. The non-oriented electrical steel sheet according to claim 1, wherein the yield stress is CYS (MPa) or more represented by the following formula.
Record
CYS = 180 + 5600 [% C] + 95 [% Si] + 50 [% Mn] + 37 [% Al]
+435 [% P] +25 [% Ni] + 22d ^-1/2
Where d: average grain size (mm) of crystal grains In Claim 1 or 2, as a component composition, the 1 type (s) or 2 or more types further selected from Zr, V, Sb, Sn, Ge, B, Ca, rare earth elements, and Co in mass%,
For Zr and V, 0.1 to 3.0%,
0.002 to 0.5% for Sb, Sn and Ge,
0.001 to 0.01% for B, Ca and rare earth elements, respectively
0.2 to 5.0% for Co
Non-oriented electrical steel sheet you characterized by containing at. % By 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, consisting of the remaining Fe and inevitable impurities, the steel slab is hot-rolled and then cold-rolled or warm-rolled to the final thickness. Then, after heating to (Cu solid solution temperature + 10 ° C) or higher, finish annealing is performed to cool from the Cu solid solution temperature to 400 ° C at a rate of 10 ° C / s or higher, and then to a temperature of 400 ° C or higher and 650 ° C or lower. method for producing a non-oriented electrical steel sheet you characterized by applying aging treatment Te. % By 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% to 4.0%, and one or more selected from Zr, V, Sb, Sn, Ge, B, Ca, rare earth elements and Co,
For Zr and V, 0.1 to 3.0%,
0.002 to 0.5% for Sb, Sn and Ge,
0.001 to 0.01% for B, Ca and rare earth elements, respectively
0.2 to 5.0% for Co
The steel slab, which is composed of the remaining Fe and the inevitable impurities, is subjected to hot rolling, followed by cold rolling or warm rolling to obtain the final thickness, and then (Cu solid solution temperature) + 10 ° C) or higher, and then finish annealing to cool from the solid solution temperature of Cu to 400 ° C at a rate of 10 ° C / s or higher, and then perform an aging treatment at a temperature of 400 ° C or higher and 650 ° C or lower. method for producing a non-oriented electrical steel sheet shall be the features.

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