JP2000129409A - Nonoriented silicon steel sheet excellent in actual machine characteristic of rotary machine and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent actual machine characteristics and to attain the reduction of core loss as well by controlling the hot rolling conditions and recrystallizing ratio in a steel sheet in which the contents of C, Si, Mn, Sb and Sn are specified, and the content of impurities is specified. SOLUTION: As the steel compsn., the one contg., by weight, <=0.010% C, 0.1 to 7.0% Si and 0.0003 to 0.20% Sb+Sn, and, as impurities, contg. <=0.0050% S, <=0.0040% N, <=0.0030% O, <=0.0030% Ti, <=0.0030% Zr, <=0.0050% V, <=0.0010% B and <=0.0050% Nb is preferable. The cumulative draft of four passes at the poststage of finish rolling in hot rolling for the steel having this compsn. is controlled to 65 to 95%, the coiling temp. is controlled to <=700 deg.C, the recrystallizing ratio is controlled to <=40%, and the draft in cold rolling is controlled to 75 to 98%. In this way, the nonoriented silicon steel sheet in which the anisotropic constant of magnetic permeability is controlled to <=1.07, the anisotropic constant of core loss is controlled to <=1.05, and the value of B50 by a 4 direction measuring method satisfies B50/Bs>=0.80 is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet used for an iron core of an electric motor or a generator, and more particularly to a non-oriented electrical steel sheet excellent in the characteristics of a rotating machine and its manufacturing method.

[0002]

2. Description of the Related Art Non-oriented electrical steel sheets are materials used for iron cores of generators, electric motors, small transformers, etc. In order to reduce energy conservation, energy loss in electric motors and generators is reduced. It has to be reduced, and improvement of electromagnetic characteristics such as iron loss has been attempted. Conventionally, non-oriented electrical steel sheets generally have low iron loss (W _15/50 (W / kg)) when magnetized to 1.5 T at a frequency of 50 Hz, and 5000 A /
It is evaluated based on the high magnetic flux density (B ₅₀ (T)) when magnetized with a magnetizing force of m. The measuring method is based on a standard Epstein test method in which half of the sample is magnetized in the rolling direction and the remaining half is magnetized in a direction perpendicular to the rolling direction.

[0003] As a method of reducing iron loss of a non-oriented electrical steel sheet, a method of containing Si, Al or Mn to increase the electrical resistance of the steel sheet, reducing impurities such as S, O, N in the steel sheet, Examples of the method include increasing the crystal grain growth and increasing the crystal grain size of the product, and improving the crystal texture of the product to a desirable one. However, the first method deteriorates the rollability of the steel sheet and the workability during product processing,
It is difficult to step up significantly from the current situation,
As for the second impurity, S is less than 20 ppm, O is less than 10 ppm, N
Has reached a level of 15 ppm or less, and even if it is further reduced, the effect of improving the magnetic characteristics is not so large as compared with the cost increase.

A third method is a method of reducing the texture of the (111) orientation, which is an unfavorable crystal orientation in terms of magnetic characteristics. As a typical method, the crystal grain size before cold rolling is increased. The recrystallization of the (111) grains generated from the old crystal grain boundaries is suppressed, and the (111) grains generated from the deformed band in the old crystal grains (11)
0) There is a method of increasing the density of grains. As a development of this method, as described in JP-A-55-97426 or Japanese Patent No. 2501219, hot-rolled sheet annealing is performed at a high temperature for a short time, and the steel sheet before cold rolling is There is a method of increasing the crystal grain size or a method of annealing a hot-rolled sheet at 800 to 950 ° C. for a long time. In addition, JP-B-56-54370 and JP-B-58
As disclosed in Japanese Patent No. -30926, a hot-rolled sheet containing Sb or Sn in steel is annealed at 700 to 1000 ° C., and the grain size before rolling is coarsened, and at the same time, Sb or Segregate Sn,
There are ways to further enhance the effects described above.

[0005]

However, all of these methods reduce the texture of the {111} <uvw> system of the product and increase the number of grains having the (110) [001] orientation. Therefore, in order to evaluate the electromagnetic properties of the non-oriented electrical steel sheet, a measurement test (hereinafter simply referred to as simply referred to as a conventional method) in which half of the sample is magnetized in the rolling direction and the remaining half is magnetized in the direction perpendicular to the rolling direction is used. According to the “standard measurement method”, even if a good result was obtained, the actual machine characteristics of the rotating machine such as the generator and the electric motor were not necessarily good. This is because the conventional standard measurement method is suitable for applications where characteristics in only two directions are important, such as the E1 core,
This is because it was not suitable for an application requiring good characteristics in all directions, such as a rotating machine.

The present invention has been made in view of the above circumstances, and in order to obtain excellent actual machine characteristics when a non-oriented electrical steel sheet is used particularly for an iron core of a rotating machine such as a generator or a motor. First, the purpose of the present invention is to establish an evaluation standard for a non-oriented electrical steel sheet used for the above-mentioned application, and to propose a product satisfying the evaluation standard and a manufacturing method thereof.

[0007]

Means for Solving the Problems The inventor of the present invention has made intensive studies to solve the above-mentioned problems, and for the characteristics of a rotating machine, a conventional standard for measuring a characteristic value in a rolling direction and a direction perpendicular to the rolling direction. in addition to the measurement method, it characteristic value of anisotropy in consideration of the measured value in a direction of ± 45 ° to the rolling direction is important, and the ratio of magnetic flux density B ₅₀ with respect to the saturation magnetic flux density Bs important In order to establish the evaluation criteria, and to achieve the evaluation criteria, it is necessary to make the hot-rolled sheet annealing different from the conventional ones to suppress the recrystallization and promote the recovery. The present invention has been newly found and the present invention has been completed.

According to the present invention, first, the anisotropy constant of the magnetic permeability at 1.0 T and 50 Hz is 1.07 or less, the anisotropy constant of the iron loss at 1.5 T and 50 Hz is 1.05 or less, and B _{50 is} measured by a four-direction measurement method.
Satisfying B ₅₀ /Bs≧0.80, the characteristics of the rotating machine made of non-oriented electrical steel sheet are improved.
Here, the four-direction measurement method is a rolling direction, a direction perpendicular to the rolling direction, and an Epstein test or the like performed on a total of 500 g of test pieces of the same amount cut out from a direction of ± 45 ° with respect to the rolling direction. Say.

According to the present invention, as a preferred composition of the non-oriented electrical steel sheet, C: 0.010% or less and Si: 0.1 to
7.0%, Mn: 0.03 to 3.5%, total amount of one or two of Sb and Sn: 0.003 to 0.20%
S: 0.0050% or less, N: 0.0040% or less, O: 0.0030% or less, T
i: 0.0030% or less, Zr: 0.0030% or less, V: 0.0050% or less,
B: limited to 0.0010% or less, Nb: limited to 0.0050% or less, with the balance substantially consisting of Fe.

Further, in addition to the above composition, Al: 0.10 to 2.0
%, P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5
%, Cr: at least one of 0.01 to 1.0%, or Al: 0.001% or less, and P:
0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Cr:
At least one of 0.01 to 1.0% is contained.

Further, as a method for producing the non-oriented electrical steel sheet, C: 0.010% or less, Si: 0.1 to 7.0%, M:
n: A steel slab containing 0.03 to 3.5% is formed into a hot-rolled sheet by hot rolling, and after annealing of the hot-rolled sheet, comprises a series of steps of performing a single cold rolling to a final sheet thickness, and further performing a finish annealing. In the manufacturing process of the non-oriented electrical steel sheet, the composition of the steel slab contains Sb and Sn in a total amount of 0.003 to 0.20%, and the impurity elements thereof, S: 0.0050% or less, N: 0.0040%
Below, O: 0.0030% or less, Ti: 0.0030% or less, Zr: 0.0030%
Below, V: 0.0050% or less, B: 0.0010% or less, Nb: 0.0050%
The hot rolling, the rolling reduction of the latter four passes of the finish rolling is 65 to 95%, and the coil winding temperature after the hot rolling is 700 ° C. or less, and the hot rolled sheet annealing is performed as follows. The recrystallization rate is reduced to 40% or less while recovering the rolling strain, and the cold rolling is performed with a reduction rate of 75 to 98%.

Further, in the above-mentioned production method, the slab further contains Al: 0.10 to 2.0%, P: 0.01 to 0.30%, Cu: 0.01 to 1.
0%, Ni: 0.01-0.5%, Cr: 0.01-1.0% or more, or Al: 0.001% or less,
P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, C
r: It is preferable to contain one or more of 0.01 to 1.0%.

[0013] The hot-rolled sheet annealing includes heat holding and self-annealing at 600 to 700 ° C for 10 minutes or more;
Min or continuous or box annealing or at 650 ~ 850 ℃
Any of continuous annealing for 3 seconds or more.

[0014] In addition, the present invention provides that
The effect of each of the above-mentioned inventions is made more remarkable by warm rolling at a temperature of 450 ° C.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail, including experimental results leading to the invention. Molten steel having each composition of A, B and C shown in Table 1 was cast by continuous casting to form seven slabs each having a thickness of 230 mm. 1170 for each slab
The sheet was heated at a temperature of 3 ° C. for 3 hours, rough-rolled into a sheet bar, and then finish-rolled into a hot-rolled sheet having a thickness of 2.2 mm. The hot rolling end temperature was 820 to 840 ° C. in all cases. Immediately after the hot rolling was completed, jet water was sprayed to rapidly cool and wind up at 500 ° C. The obtained hot-rolled sheet is annealed and then cold-rolled to a final thickness of 0.5 mm, and further has a dew point of −20 ° C. and 75% H _2.
Annealing was performed at 1000 ° C. for 1 minute in a mixed atmosphere of + 25% N ₂ , and an organic / inorganic mixed coat was applied to obtain a product. Table 2 shows the hot rolling schedule and annealing conditions at that time.
The treatment symbols 1 to 7 shown in FIG.

[0016]

[Table 1]

[0017]

[Table 2]

With respect to the process of the above-mentioned experimental process and the obtained product, the structure and characteristic values were measured as follows. Recrystallization rate of cross section of steel sheet before and after annealing of hot rolled sheet (percentage of area occupied by recrystallized grains with respect to total viewing area) Epstein test by standard measurement method for products and various tests by four-way measurement method Measurement of motor efficiency (stator Outer diameter 130mm, rotor diameter 50m
m, 70 mm long, 3 phase 6 pole 120Hz, 120v, 400w induction motor) The measurement results are shown in Table 3.

[0019]

[Table 3]

As shown in Table 3, A-4 (when the treatment A was performed on steel A, the same applies hereinafter), A-5, B-4, B-5, B-6 and C
-4, C-5, and C-6 have excellent magnetic flux density and iron loss in the standard measurement method, but the motor efficiency is excellent only in the case of A-2. That is, the magnetic efficiency of the product is not necessarily reflected in the motor efficiency. As a result of investigating the reason, the measurement of magnetic properties by the two-way measurement test is inferior for the product of A-2,
The magnetic properties of the four-way measurement test are as follows: iron loss W _15/50 is 2.325 W / kg
(On the other hand, A-6 is 2.483 W / kg), which is an extremely good value. In the case of A-2,
The value of the magnetic permeability at 1.5T and 50Hz in the four-direction measurement method is 12310
Although it was as high as G / θ, the A-6 had only 11590 G / θ, which caused the motor efficiency to decrease.

The discrepancy of the measured values between the standard measuring method and the four-direction measuring method is mainly due to the crystal structure of the steel sheet.
Brought by the texture. That is, in the measurement by the standard measurement method, a material having an excellent texture only in two directions, ie, the rolling direction and the direction perpendicular to the rolling, is particularly advantageously evaluated. Fewer textures are more advantageously evaluated and are more appropriate for evaluating the characteristics of a rotating machine. Incidentally, the main texture of the crystal structure of the product of A-2 was {100} <uvw>.

As described above, the difference between the result obtained by the standard measurement method and the result obtained by the four-direction measurement method is an index indicating the anisotropy of the material. In the present invention, the anisotropy constant is defined by the ratio between the two. . That is, the anisotropy constant of iron loss is 4
W the value of W _15/50 by direction measurement method using the standard measurement method _15/50
The value obtained by dividing the value of the permeability at 1.0 T, 50 Hz by the standard measurement method into 4 is used as the permeability anisotropy constant.
The value obtained by dividing by the value of the magnetic permeability of 1.0 T, 50 Hz by the direction measurement method is adopted. The closer the anisotropy constant is to 1, the weaker the anisotropy is, which is advantageous for motor characteristics.

In this case, the measurement conditions of the four-direction measurement method for a rotating machine material such as a motor are as described above.
For iron loss, the condition of 1.5T, 50Hz is generally accepted, and for the magnetic permeability, the condition of 1.0T, 50Hz is generally accepted.However, naturally, for the design magnetic field and the motor designed for high frequency, The measurement conditions on the lower magnetic flux degree side, higher magnetic flux density side, or higher frequency side can be adopted.

Further, the present inventor has found that B ₅₀ /
Bs value and the motor efficiency is good correlation was obtained knowledge that in order to obtain a good motor efficiency is required to be B ₅₀ / Bs 0.8 or more. Here Bs and the a saturation flux density of the electromagnetic steel sheet, B ₅₀ is the largest field of 5000A / m, means the maximum magnetic flux density at 50 Hz. Even if the Bs value is simply high, when the anisotropy is large, the improvement of the characteristics of the actual machine for rotation such as a motor is not remarkable. Since the value of B ₅₀ / Bs cannot exceed 1, the material whose B ₅₀ / Bs is close to 1 is a material suitable for a rotating machine.

That is, the teeth portion of the motor is a portion where the volume is particularly small in the motor, and the magnetic flux concentrates. Therefore, unless the magnetic flux density in that portion is high, the actual machine characteristics of the motor are not improved. Moreover, the teeth of the motor are distributed in all directions at 360 ° with respect to the rolling direction of the magnetic steel sheet, and the standard measurement method that evaluates only the rolling direction and the direction perpendicular to the rolling cannot meet such conditions. The value of B ₅₀ / Bs calculated using the value of B ₅₀ by the four-direction measurement method is more appropriate for evaluating the material properties of the teeth portion and replaces the conventional standard.

As described above, the present invention reexamines the characteristics of a non-oriented electrical steel sheet from the aspect of the actual characteristics of a rotating machine, establishes a new evaluation criterion, and provides a non-directional It proposes an electromagnetic steel sheet. However, the present invention does not deny the value of iron loss value W _15/50 and the magnetic flux density B ₅₀ is a measure of the conventional, it is natural that more is effective if better these values is there.

The means for producing the non-oriented electrical steel sheet having the characteristics of the present invention will be described below.

First, it is necessary to contain Sn and / or Sb as a composition of a slab as a starting material. Table 3
Comparing A-2 and B-2 shown in the above, these are the same hot rolled,
Despite undergoing the heat treatment step and the cold rolling step, the crystal structure of A-2 is mainly composed of a {100} <uvw> texture, exhibiting excellent rotating machine characteristics, whereas B-2 The result of the -2 four-way measurement method is that the iron loss value, magnetic flux density and magnetic permeability are inferior, and the organization is {111}
<Uvw> is the main orientation, and although the anisotropy is small, it is not preferable in terms of magnetic properties.

The difference between A-2 and B-2 lies in whether or not the steel contains grain boundary segregation elements such as Sn and Sb. Investigating the effects on Sn and Sb in more detail, when these elements contain 0.003% to 0.20% in total amount, these elements segregate at the grain boundaries before cold rolling, annealing after cold rolling In the step, recrystallization of {111} <uvw> oriented grains is suppressed, and recrystallization of grains having {100} <uvw> as the main crystal orientation.
It was found that grain growth was promoted. Therefore, Sn or Sb alone or in combination contains 0.003% or more in total. However, if it exceeds 0.20%, the workability deteriorates and it is not practical, so it is limited to 0.20% or less.

Next, the crystal grains are sufficiently grown, and {100}
<Uvw> It is necessary to take measures to develop the texture. One of the conditions is the addition of an appropriate amount of Sn or Sb described above. By the way, the A-2 has a crystal grain size of 120μ.
m-2, whereas B-2 was 90 μm.

However, this is not enough. It is necessary to sufficiently reduce the content of the impurity element. This means that when the same treatment 2 as that of steel A (see Table 2) was performed using steel C, steel C contained Sb similarly to steel A, and as shown in Table 3, the transparency was measured by the four-direction measurement method. Despite showing a good value in magnetic susceptibility, in the case of C-2, the crystal grain size was 55
It is clear from the fact that the iron loss value is increased and the motor efficiency is deteriorated. In the case of C-2, although the texture is {100} <uvw>, its strength is weak, and therefore it is determined by the four-direction measurement method.
B ₅₀ / Bs was also inferior.

As impurities, S: 0.0050% or less, N: 0.0
In addition to 040% or less, O: 0.0030% or less, it is necessary to limit to Ti: 0.0030% or less, Zr: 0.0030% or less, V: 0.0050% or less, B: 0.0010% or less, and Nb: 0.0050% or less. By reducing these impurities, a {100} <uvw> texture, which has conventionally been considered to have a very low driving force for recrystallization and grain growth and a small crystal grain size and easy grain refinement, can be sufficiently developed. Can be.

In order to obtain a non-oriented electrical steel sheet excellent in actual machine characteristics of the rotating machine according to the present invention, it is necessary to introduce sufficient strain into the hot rolled sheet by hot finish rolling. By the way,
For steel A, when only the hot rolling schedule was changed, better magnetic properties for the rotating machine were obtained when treatment 2 was performed (A-2) than when treatment 1 was performed (A-1). It has become. In the present invention, the degree of introduction of strain during hot finish rolling is evaluated by the cumulative rolling reduction of the last four passes of finish rolling, and the value is set to 65% or more. This allows
High-density processing strain can be contained in the hot-rolled coil. However, when the content exceeds 95%, the finish rolling itself becomes difficult. In order to increase the rolling reduction in the latter stage of the finish rolling, it is possible to take measures such as omitting rough rolling if necessary.

In annealing the hot-rolled sheet with the strain introduced as described above, it is necessary to employ conditions for suppressing recrystallization while removing the strain from the hot-rolled sheet. Thereby, the sub-grain structure inside is improved during the annealing process of the hot-rolled sheet, particularly during the recovery process. That is, from the old grain boundary and the deformation zone in the old crystal grain, {111} <
uvw> can be suppressed, and the recrystallization of the grains having the orientation of {100} <uvw> from the old crystal grains can be promoted.

Specifically, first, the coiling temperature of the hot-rolled coil after finishing rolling is set to 700 ° C. or less. When the coil winding temperature is set to a temperature exceeding 700 ° C., a part of the steel sheet starts recrystallization, thereby increasing the texture of the {111} <uvw> orientation, and increasing the efficiency of the actual rotating machine. It is because it falls. For this reason, after the hot rolling is completed, it is preferable to take measures such as spraying jet water on the exit side of the finishing rolling mill so that the winding temperature is 700 ° C. or less.

Next, the above hot rolled sheet is subjected to a heat treatment for reducing the recrystallization rate to 40% or less while recovering the rolling strain. If the recrystallization ratio exceeds 40%, the recrystallization grain boundary is reduced by 11%.
This is because the number of recrystallized grains in the 1｝ <uvw> direction increases, and the texture and magnetic properties of the product deteriorate. By the way,
As can be seen by comparing A-2 with A-4, A-5 or A-6, in the case of A-4, A-5, A-6, the recrystallization rate of the steel sheet before cold rolling is Therefore, after cold rolling and finish annealing, recrystallization with {111} <uvw> as the main orientation progresses from the crystal grain boundary of the recrystallized grains, resulting in deterioration of magnetic properties. This has been confirmed from other experimental results. Therefore, the temperature and time of the heat treatment must be selected to reduce the recrystallization rate to 40% or less. The recrystallization rate refers to the ratio of recrystallized grains after heat treatment of a target steel sheet, and is defined by the percentage of the area occupied by the recrystallized grains with respect to the entire viewing area.

The specific conditions of the heat treatment can be performed in the following manner. Heat retention and self-annealing for 10 minutes or more at 600 to 700 ° C In this case, the coil winding temperature is set to 600 to 700 ° C,
After winding, it is kept warm in a suitable warming device and self-annealed. Continuous or box annealing at 500 to 700 ° C. for 10 minutes or more In this case, the coil that has been wound at a low temperature or the coil that has been cooled after winding is box-annealed in the coil state or unwound and continuously annealed. Continuous annealing at 650 to 850 ° C. for 3 seconds or more In this case, the coil that has been wound at a low temperature or the coil that has been cooled after winding is rewound and continuously annealed.

However, when heat treatment is performed at a temperature of 700 ° C. or more for 10 minutes or more or at a temperature of 850 ° C. or more for 3 seconds or more, recrystallization proceeds rapidly, and the frequency of appearance of recrystallized grains in an undesired orientation is increased. Is not appropriate because Therefore, it is important that the upper limit of the temperature and time of the heat treatment is regulated while employing the above means, so that the recrystallization rate is 40% or less.

After the above-mentioned required heat treatment, the hot-rolled steel sheet is cold-rolled to a final thickness. At this time, the rolling reduction of the cold rolling is set to 75 to 98%. By setting the cold rolling at 75% or more, it is possible to suppress the texture more preferably. However, setting the content to 98% or more is 75 to 98% because it is industrially impossible.

Although the basic configuration of the present invention has been described above, the general conditions for carrying out the present invention will be described below, which is not the essence of the present invention.

First, the electromagnetic steel sheet contains the following components in addition to Sn and Sb. C: 0.010% or less C is a harmful element for obtaining good magnetic properties.
The content is 0.010% (% by weight, the same applies hereinafter).

Si: 0.1 to 7.0% Si is an element effective for increasing electric resistance and reducing iron loss, and contains 0.1% by weight or more. However, if the content exceeds 7.0% by weight, processing becomes difficult, so the content is set to 0.1 to 7.0%.

Mn: 0.03 to 3.5% Since Mn also has the effect of increasing electric resistance and reducing iron loss,
0.03% or more is contained. However, if it exceeds 3.5%,
Transformation occurs at the time of high-temperature finish annealing, and iron loss deteriorates.

Al: 0.10% or more or 0.001% or less Al is effective because it has an effect of increasing electric resistance and reducing iron loss. In order to obtain the effect, it is preferable to contain 0.10% or more. However, when the content exceeds 2.0% by weight, the oxidation and nitriding of the steel sheet progresses, leading to deterioration of iron loss. Therefore, the content is preferably set in the range of 0.10 to 2.0% by weight. On the other hand, when the content of Al is less than 0.10%, AlN is formed, and the grain growth is impaired and iron loss is deteriorated.Therefore, when Al is not added, it is necessary to limit the content to 0.001% or less. is there.

It is also effective to include P, Cu, Ni, and Cr in addition to the above-mentioned elements, because they have an effect of increasing electric resistance and reducing iron loss. Therefore, P is 0.01-0.30% and Cu is 0.
It can contain 01-1.0%, Ni 0.01-0.5%, and Cr 0.01-1.0%. The contents of Sn and Sb and the restrictions on the impurity elements are as described above.

The steel having the above composition is formed into a slab by continuous casting by a conventional method, heated to a slab, then hot-rolled into a hot-rolled coil, and further cold-rolled. At that time, for energy saving, it is also possible to employ means for directly performing hot rolling after continuous casting without performing slab heating, or means for maintaining the temperature of the slab. In the case of cold rolling, when the content of the electric resistance increasing component such as Si in the material is high, warm rolling at 100 to 400 ° C. can be performed. The conditions of the hot rolling and the cold rolling, which are features of the present invention, have already been described in detail.

The steel sheet having the final thickness by cold rolling is:
The product is subjected to finish annealing at a high temperature to grow crystal grains, thereby obtaining a product. In this case, it is possible to apply an inorganic, organic, or semi-organic insulating coating to the surface of the steel sheet, if necessary, without hindering the use of a so-called semi-process. It is also possible to increase the roughness of the steel sheet surface for the purpose of improving weldability.

[0048]

Example 1 Molten steel having a composition of steel symbol D shown in Table 4 was continuously cast, and 18 slabs having a thickness of 220 mm were produced at 1220 ° C.
, And then roughly rolled to a thickness of 40 mm. Furthermore, it is 40mm →
The coil was hot rolled into a 2.2 mm thick coil according to a pass schedule of 30 mm → 18 mm → 10 mm → 6.4 mm → 4.8 mm → 3.2 mm → 2.2 mm (cumulative rolling reduction at the latter stage 4 passes: 72%). Hot rolling end temperature is 8
After completion of hot rolling, it was rapidly cooled at a speed of 40 to 55 ° C./s by jet water jet and wound at a temperature of 580 to 600 ° C.

[0049]

[Table 4]

After pickling, these coils were subjected to hot-rolled sheet annealing at a temperature of 520 to 700 ° C. for 30 minutes to 10 hours, and then rolled to a thickness of 0.35 mm by a tandem rolling mill (cold rolling). Rate: 9
2.5%), degreased, subjected to finish annealing at 1050 ° C for 40 seconds, and coated and baked with a semi-organic coat mainly composed of magnesium dichromate and an organic resin.

[0051] Test pieces were cut out from each product, performs the Epstein magnetic measuring according to standard assays, magnetic measurement by 4 direction measuring method, the iron loss of W _15/50, flux density B _50, 1.0 T, 5
The magnetic permeability at 0 Hz was obtained. Further, the values of the anisotropy constant of iron loss, the anisotropy constant of magnetic permeability, and B ₅₀ / Bs were determined. further,
From these products, an 8-pole 200 Hz, 60 V DC brushless motor having a stator outer diameter of 220 mm, a rotor diameter of 120 mm, and a body length of 60 mm was manufactured, and its efficiency was measured. After the hot-rolled sheet annealing, the recrystallization rate of the steel sheet was measured.

FIG. 1 shows the relationship between the motor efficiency and the recrystallization rate of the crystal structure after the hot-rolled sheet annealing.
In addition, anisotropy constant of iron loss W _15/50 of the above product, 1.5T, 50Hz
FIG. 2 shows the anisotropy constant of the magnetic permeability and the relationship between the value of B ₅₀ / Bs and the motor efficiency.

As shown in FIG. 1, an excellent motor efficiency was obtained by the method of the present invention in which the recrystallization rate was set to 40% or less in hot-rolled sheet annealing at a temperature of 500 ° C. or more. In order to obtain motor efficiency, the anisotropy constant of iron loss W _15/50 is 1.05 or less, and the anisotropy constant of permeability at 1.0 T and 50 Hz is 1.07 or less, and the value of B ₅₀ / Bs is It has been demonstrated that it is necessary to be 0.80 or more.

[0054]

Example 2 Molten steel having the composition of steel symbols E, F and G shown in Table 5 was continuously cast into seven slabs each having a thickness of 220 mm, and directly hot-rolled at a temperature of 1000 ° C. or more. And hot-rolled into a coil having a thickness of 2.0 mm. The end temperature of hot rolling was 780 to 810 ° C in all cases. Immediately after the end, jet water was sprayed, rapidly cooled at a rate of 40 ° C / s, and wound at 500 ° C. The obtained coil was subjected to required heat treatment after pickling. The rolling schedule and annealing conditions for each of the seven slabs obtained from the same steel symbol are as shown in Table 6.

[0055]

[Table 5]

[0056]

[Table 6]

As described above, the obtained hot rolled sheet is
It was rolled to a final thickness of 0.35 mm. Cold reduction
Was 82.5%. A dew point of -20 ° C, 7
5% H _Two+ 25% N_TwoAnneal in an atmosphere at 1000 ° C for 1 minute.
An inorganic coat consisting mainly of aluminum phosphate is applied
Goods.

From the obtained product, a sample of 30 × 280 mm was sampled and subjected to magnetic measurement. Using this test piece, magnetic measurement was performed by the standard measurement method and the four-direction measurement method, and the iron loss value (W
_15/50 ), magnetic flux density (B ₅₀ ), 1.0T, permeability at 50 Hz (G /
θ) was determined. Further, the values of the anisotropy constant of iron loss, the anisotropy constant of magnetic permeability, and B ₅₀ / Bs were determined. Furthermore, a single-phase 4-pole 300 Hz DC brushless motor having a stator outer diameter of 150 mm, a rotor diameter of 60 mm, and a body length of 80 mm was fabricated from these products, and its efficiency was measured. After the hot-rolled sheet annealing, the recrystallization rate of the steel sheet was measured. The test results are summarized in Table 7.

[0059]

[Table 7]

As is clear from Table 7, the steel E that has undergone treatment 1 (abbreviated as E-1; the same applies hereinafter), E-6,
The F-4, F-6, G-4, and G-6 products have excellent magnetic flux density and iron loss value by the standard measurement method, but the motor efficiency is equivalent to the symbols E-2 and E-5. The product is excellent. Furthermore, the magnetic property evaluation of the material obtained from the standard measurement method and the four-direction measurement method showed that the anisotropy constant of iron loss was
1.014, the anisotropy constant of permeability is 1.032, 1.038,
In addition, the values of B ₅₀ / Bs were 085 and 0.84, which were extremely excellent values.

[0061]

Example 3 A slab having the composition of steel symbols H to O and Q and R shown in Table 8 was cast while applying electromagnetic stirring to a thickness of 25%.
The slab was 0 mm. After heating the obtained slab to 1200 ° C., it was roughly rolled to form a 35 mm-thick sheet bar.
Hot finish rolling by pass tandem rolling mill, 2.4m
m hot rolled coil. The pass schedule at this time is 3
5mm → 27mm → 18mm → 10.2mm → 6.8mm → 4.0mm → 2.4mm pass schedule (cumulative rolling reduction of 4 passes in the latter stage: 86.6%)
The hot rolling end temperature is 850 ° C. for coils with steel symbol H, 830 ° C. for coils with steel symbols I to K, and 790 for coils with steel symbols L and M.
C., coils of steel symbols N, O, Q and R were 760 ° C. In addition, jet water is sprayed immediately after hot rolling is completed.
It was quenched at a rate of 50 to 65 ° C / s and wound at a temperature of 550 ° C.

[0062]

[Table 8]

The obtained coil was divided into two parts, one of which was annealed according to the present invention, and the other as a comparative example, which was out of the conditions according to the present invention. Annealing according to the invention is as follows: steel H at 550 ° C. for 6 hours, steels I to K at 550 ° C. for 6 hours, steels L and M at 550 ° C. for 1 hour, steels N, O, Q and R at 530 ° C. at 3 hours. It was box annealing in the coil state for a long time. On the other hand, the annealing of the comparative example is continuous annealing after pickling, and steel H is 950 ° C. for 2 minutes,
Steel I to K at 920 ° C for 2 minutes, Steel L to O and Q and R at 860 ° C
For 5 minutes.

The annealed coil was cold-rolled by a tandem rolling mill to a thickness of 0.50 mm (cold rolling reduction: 79.5%),
After further degreasing, the steel sheets I to K are heated at 1050 ° C for 1 minute,
Steel L and M steel plates at 1000 ° C for 1 minute, steel N and O steel plates 830
℃ 1 minute, steel Q steel plate at 800 ℃ 2 minutes, steel R steel plate 780
Finish annealing was performed at 2 ° C. for 2 minutes, and an organic / inorganic mixed coat was applied to obtain a product.

From the obtained product, a sample of 30 × 280 mm was sampled and subjected to magnetic measurement. The measurement was performed by the Epstein test as a standard measurement method and the four-direction measurement test. further,
From these products, a single-phase, 4-pole, 100 Hz CD brushless motor having a stator outer diameter of 100 mm, a rotor diameter of 40 mm, and a motor body length of 30 mm was manufactured, and the efficiency of these motors was measured. After the hot-rolled sheet annealing, the recrystallization rate of the steel sheet was measured.

Table 9 summarizes the measurement results. As shown in Table 9, the products manufactured according to the present invention have low anisotropy, and extremely good motor efficiency is obtained as compared with the comparative material.

[0067]

[Table 9]

[0068]

Example 4 A molten steel having a composition of steel symbols P and S shown in Table 10 was applied to a continuous casting machine with a thickness of 50 mm while applying electrolytic stirring.
2 thin slabs were cast. After the slab was cast, when the slab center temperature reached 1220 ° C. during cooling, the slab was subjected to immediate finish rolling by a tandem rolling mill of seven stands according to the following two pass schedules to obtain a hot-rolled coil. 50mm → 38mm → 28mm → 20mm → 12.5mm → 7.2mm → 4.2mm →
2.7mm (cumulative rolling reduction in the latter four passes: 86.5%) 50mm → 34mm → 25mm → 18mm → 11.8mm → 5.4mm → 3.0mm → 1.
8mm (cumulative rolling reduction of the latter 4 passes: 90.0%)

[0069]

[Table 10]

The hot rolling end temperature is 750 ° C. After the hot rolling is completed, the hot rolling is cooled at a rate of 22 to 25 ° C./s, and wound at 620 ° C.
A coil protection cover was provided, and a heat treatment of staying at a temperature of 620 to 640 ° C. for 1 hour was performed.

The obtained hot-rolled coil was pickled and then rolled to a thickness of 0.50 mm using a tandem rolling mill. In this case, the cold rolling reduction is 81.5%, which corresponds to the invention example, and in the case of 72.
2%, which corresponds to the comparative example. After cold rolling and degreasing, the steel sheet with steel symbol P was subjected to finish annealing at 820 ° C for 30 seconds, and the steel sheet with steel symbol S was subjected to finish annealing at 780 ° C for 1 minute, and then an organic and inorganic mixed coat was applied. Product.

From the obtained product, a sample of 30 × 280 mm was sampled and subjected to magnetic measurement. The measurement was based on a standard measurement method and a four-way measurement method. Furthermore, from these products, three phases of stator outer diameter 150mm, rotor diameter 80mm, body length 70mm, 6
Induction motors with poles of 120 Hz were fabricated, and the efficiency of these motors was measured. The results are summarized in Table 11. As shown in Table 11, the product of the present invention example showed B
The value of ₅₀ / Bs is large, the iron loss and the anisotropy of the magnetic permeability are low, and the motor efficiency is good.

[0073]

[Table 11]

[0074]

Since the present invention is constructed as described above, the non-oriented electrical steel sheet used for a rotating machine such as a motor can be made to have extremely excellent actual machine characteristics as compared with the prior art. It can be carried out industrially, thereby obtaining a great energy saving effect.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between motor efficiency and the recrystallization rate of a crystal structure after hot-rolled sheet annealing.

FIG. 2 shows anisotropy constants of motor efficiency, iron loss and magnetic permeability,
It is a graph showing the relationship between the value of B ₅₀ / Bs.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 1/16 H01F 1/16 A F term (Reference) 4K033 AA01 CA01 CA02 CA03 CA07 CA08 CA09 FA05 FA10 FA13 FA14 HA02 HA04 5E041 AA02 AA11 AA19 CA04 HB05 HB07 HB11 NN01 NN13 NN15 NN17 NN18

Claims (9)

[Claims] 1. Anisotropy constant of magnetic permeability at 1.0T, 50Hz
1.07 or less, 1.5T, anisotropy constant of iron loss at 50Hz is 1.05
Below, and B by the four-way measurement method₅₀Is B ₅₀/ Bs ≧ 0.
Excellent in actual machine characteristics of rotating machine characterized by satisfying 80
Non-oriented electrical steel sheet. 2. The composition has a C content of not more than 0.010% by weight,
i: 0.1 to 7.0%, Mn: 0.03 to 3.5%, one or two of Sb and Sn
Total amount of species: 0.003 to 0.20%, and impurity elements S: 0.0050% or less, N: 0.0040% or less, O: 0.0030% or less, Ti: 0.0030% or less, Zr: 0.0030% or less, V: 0.0050 %, B: 0.0010% or less, Nb: 0.0050% or less, and the balance is substantially made of Fe. Electrical steel sheet. 3. The composition further comprises: Al: 0.10 to 2.0%,
P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, C
3. The non-oriented electrical steel sheet according to claim 2, wherein the non-oriented electrical steel sheet has at least one of r: 0.01 to 1.0%. 4. The composition further includes Al: 0.001% or less, P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni:
3. The non-oriented electrical steel sheet according to claim 2, wherein said non-oriented electrical steel sheet has at least one of 0.01 to 0.5% and Cr: 0.01 to 1.0%. 5. C: 0.010% or less by weight, Si: 0.1 to
A steel slab containing 7.0% and Mn: 0.03 to 3.5% is made into a hot-rolled sheet by hot rolling, and after hot-rolled sheet annealing, it is made to have a final thickness by cold rolling, followed by a series of steps of finish annealing. In the method for producing a non-oriented electrical steel sheet, the steel slab contains Sb, Sn in a total amount of 0.003 to 0.20%, and the impurity element, S: 0.0050% or less,
N: 0.0040% or less, O: 0.0030% or less, Ti: 0.0030% or less, Z
r: 0.0030% or less, V: 0.0050% or less, B: 0.0010% or less, N
b: 0.0050% or less, and the hot rolling is performed such that the cumulative rolling reduction in the latter four passes of the finish rolling is 65 to 95% and the coil winding temperature after the hot rolling is 700 ° C or less. Strip annealing reduces the recrystallization rate while recovering the rolling strain.
The method for producing a non-oriented electrical steel sheet excellent in actual machine characteristics of a rotating machine, wherein the cold rolling is performed at a rolling reduction of 75 to 98%. 6. The slab further comprises Al: 0.10 to 2.0%,
P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, C
The method for producing a non-oriented electrical steel sheet according to claim 5, wherein at least one of r: 0.01 to 1.0% is contained. 7. The slab further contains Al: 0.001% or less, P: 0.01 to 0.30%, Cu: 0.01 to 1.0%, Ni: 0.
6. The method for producing a non-oriented electrical steel sheet according to claim 5, wherein said non-oriented electrical steel sheet has at least one type of 01 to 0.5% and Cr of 0.01 to 1.0%. 8. Hot-rolled sheet annealing includes heat holding and self-annealing at 600 to 700 ° C. for 10 minutes or more, continuous or box annealing at 500 to 700 ° C. for 10 minutes or more, or continuous for 3 seconds or more at 650 to 850 ° C. 6. The method according to claim 5, wherein the method is any one of annealing.
8. A method for producing a non-oriented electrical steel sheet having excellent actual machine characteristics of a rotating machine according to any one of claims 7 to 7. 9. The method for producing a non-oriented electrical steel sheet according to claim 5, wherein the cold rolling is performed by warm rolling at 100 to 450 ° C.