JP3791226B2 - Non-oriented electrical steel sheet and manufacturing method thereof - Google Patents

Description

【００４０】
【表２】

【００４１】
【発明の効果】
このように、従来は０．５０ｍｍ以下という薄板の無方向性電磁鋼板では自動かしめができなかったのに対して、本発明によれば占積率を低下させることなく、自動かしめを可能とすることができ、今日問題となっている高周波励磁特性に優れた材料を用いた大量生産を可能とするなど、本発明の実用的価値は大きい。
【図面の簡単な説明】
【図１】実施例の結果を含めて1.5 ＜[Si]＋[Al]＋0.5 [Mn]≦5.5 の臨界性を示すグラフである。
【図２】実施例の結果を含めて板厚と鉄損 (Ｗ_10/800) との関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-oriented electrical steel sheet having high frequency excitation characteristics, automatic caulking properties, and excellent space factor, and a manufacturing method thereof, in particular, a material for shielding high frequency generating equipment such as an inverter excitation control motor, transformer, or induction heating. The present invention relates to a non-oriented electrical steel sheet having excellent high-frequency excitation characteristics, automatic caulking properties, and space factor, and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, non-oriented electrical steel sheets have been used in motors and transformers, but in recent years, it has become important to improve the efficiency of energy consuming equipment such as motors from the viewpoint of preventing global warming. For this purpose, the motor as a means for obtaining the rotational motion has conventionally been a system in which a reduction gear is attached to an AC induction motor to obtain a predetermined rotational speed or a system in which a voltage is changed by a DC motor to obtain a predetermined rotational speed. The method is inefficient and consumes extra energy. Thereafter, the technology of frequency conversion has advanced, and a technology has been developed that can obtain a predetermined rotational speed by a combination of an induction motor and an inverter.
[0003]
Further, synchronous motors (brushless DC motors) in which permanent magnets are embedded from induction motors, which have been the mainstream in the past, have become the mainstream as a result of further motor progress, and more and more are used at high frequencies. For example, hermetic motors and electric vehicle motors used for compressors of air conditioners (air conditioners) are already mainly brushless DC motors driven at a frequency higher than the conventional commercial frequency.
[0004]
In addition, universal motors used in vacuum cleaners, servo motors used in industrial robots, spindle motors for computer hard disk drives, etc., which rotate at a higher speed than before, have a high frequency due to the structure of the motor itself. It has become important that the high-frequency iron loss is low.
[0005]
As a countermeasure for these, it is effective to use a high-alloy type high-thickness electromagnetic steel sheet having a high electrical resistance, which has been described in, for example, JP-A-8-60252 and JP-A-10-25554. It has been considered effective to use a thin electrical steel sheet having a thickness of 0.50 mm or less.
However, these thin materials have a disadvantage that they are not suitable for mass production because they have a poor space factor and cannot be automatically caulked.
[0006]
[Problems to be solved by the invention]
Here, an object of the present invention is to provide a non-oriented electrical steel sheet and a method for manufacturing the same, which has excellent space factor even if it is a thin sheet having a thickness of 0.50 mm or less, particularly 0.22 to 0.42 mm. Is to provide.
[0007]
Specifically, the present invention is to provide a non-oriented electrical steel sheet excellent in high-frequency magnetic properties having a space factor of 96% or more and an automatic caulking strength of 10 MPa or more per point, and a method for producing the same.
[0008]
More specifically, it is excited not only by the conventional sine wave but also by PWM (pulse width modulation) and PAM (pulse wave amplification modulation), and its iron loss W15 / 400 (frequency 400 Hz, magnetic flux density 1.5T) It is an object of the present invention to provide a non-oriented electrical steel sheet excellent in high-frequency magnetic properties having an iron loss of less than 80 W / kg and a method for producing the same.
[0009]
[Means for Solving the Problems]
In order to solve this problem, the present inventors have made various studies. As a result, by skillfully adjusting the steel composition, automatic caulking can be performed without causing a decrease in the space factor, and high-frequency magnetic characteristics can be improved. It has been found that an electrical steel sheet can be obtained.
[0010]
Generally, iron loss is a problem in high frequency magnetic characteristics. For example, an induction motor controlled by an inverter for an air conditioner or a brushless DC motor uses a pulse width modulation type inverter, and the carrier frequency generated by the number of times of chopping is low. 2.5 to 3 kHz, and the PWM AC frequency generated by chopping is 30 to 400 Hz. It is not possible to evaluate the iron loss at AC 50 or 60 Hz, which is the conventional magnetic property evaluation method defined in JIS C-2550 (1986). It is enough.
[0011]
Therefore, in the present invention, in particular in the case of PWM excitation, a certain amount of alloy components are added in order to reduce the iron loss at 100 Hz or more, and the plate thickness, which has been the mainstream in the past, has been reduced from 0.5 mm to 0.22 to 0.42 mm. Inspired to make it thinner.
[0012]
However, as the plate thickness is reduced and the alloy composition is increased, the iron loss can be expected to decrease. However, there is a problem that the space factor is reduced and the automatic caulking cannot be performed.
[0013]
Here, the present invention has found that there is an alloy composition and a manufacturing method that can satisfy any of these requirements, and the gist thereof is as follows.
[0014]
(1) By weight%
C: 0.01% or less, Si: 3.0% or less, Mn: 0.2 to 1.5%, S: 0.035% or less, sol. Al: 0.0005 to 2.5%, P: 0.005 to 0.15%, N: 0.005% or less,
However, 1.5 <[Si] + [Al] +0.5 [Mn] ≦ 3.5
It has a steel composition consisting of the balance Fe and inevitable impurities, has high-frequency excitation characteristics, and has an automatic caulking strength of 10 MPa or more per point, a space factor of 96% or more, a plate thickness of 0.22 to 0.33 mm, an average surface A non-oriented electrical steel sheet having a roughness Ra ≦ 0.5 μm.
[0015]
(2) Thicknesses of 0.22 to 0.2 obtained by heating the steel having the steel composition described in (1 ) above to a temperature of 1250 ° C. or less, performing hot rolling, and further performing cold rolling . A 33 mm cold-rolled material is subjected to finish annealing at a temperature of 700 to 1050 ° C., and has an average surface roughness Ra ≦ 0.5 μm, high frequency excitation characteristics, automatic caulking properties, and excellent space factor. A method for producing grain-oriented electrical steel sheets.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention pays attention to Si, Al, and Mn, which are effective in reducing iron loss, among the alloy components in steel, and [Si] + [Al] +0.5 [Mn] is 1.5 from the ratio contributing to these iron losses. The slab having such a composition ratio is continuously charged in a reheating furnace having a temperature of 1250 ° C. or less for hot rolling. After hot rolling, pickling and finish annealing, pickling and cold rolling, annealing hot rolled sheet and pickling and cold rolling, or hot rolled sheet After annealing, pickling and cold rolling to an intermediate thickness are performed, and after the intermediate annealing, the final sheet thickness is cold rolled to 0.22 mm or more and 0.42 mm or less, followed by continuous annealing as finish annealing. After finishing annealing by this continuous annealing, an organic / inorganic composite or organic coating layer composed of a resin containing an inorganic binder or a resin alone is applied to the surface depending on the intended use.
The reasons for limiting the steel composition and production conditions in the present invention are shown below.
[0018]
If the steel composition C exceeds 0.01%, it causes magnetic aging and deteriorates the magnetic properties. Preferably it is 0.003% or more.
[0019]
Si is an essential element for improving the magnetic properties, but if it exceeds 3.5%, the automatic caulking property decreases and the steel itself becomes hard and the thickness accuracy decreases, so the space factor decreases. It was as follows. Preferably it is 1.0 to 3.0%.
[0020]
Mn is an element effective for improving magnetic properties, but if added over 1.5%, the automatic caulking property decreases and the steel itself becomes hard and the sheet thickness accuracy decreases, so the space factor decreases. It was. Further, if it is less than 0.2%, crystal grain growth is suppressed, and iron loss in the commercial frequency range (50, 60 Hz) becomes worse. Preferably it is 0.2 to 0.5%.
[0021]
Since addition of S is not preferable for improving the magnetic properties, it is set to 0.035% or less. When Si + Al + 0.5Mn is 2.0% or more, it is preferably 0.002% or less.
[0022]
sol.Al is an important element for improving the magnetic properties, but if it is less than 0.0005%, it becomes ultra-clean steel, and the production cost in the steelmaking stage increases remarkably. Since both rolling and cold rolling become extremely difficult, the content is set to 2.5% or less. Preferably it is 0.2 to 1.2% or 0.0005 to 0.001%.
[0023]
P is important for improving the mechanical properties for ensuring the punchability, but if it exceeds 0.15%, it causes breakage during cold rolling, so that it is made 0.15% or less, while to make it less than 0.005% Since the cost of the dephosphorization process is increased, the content is set to 0.005% or more and 0.15% or less.
[0024]
N is an element harmful to magnetic properties such as bonding with Al and making crystal grains finer, so 0.005% or less.
The sum of the elements represented by the relational expression [Si] + [Al] +0.5 [Mn] increases the electrical resistance of the steel and contributes to the improvement of the high-frequency iron loss. However, if it is less than 1.5%, the effect is not recognized. If it exceeds 5.5%, it will be difficult to perform automatic caulking. Preferably the value of the above formula is 1.5-3.5%.
[0025]
Sheet thickness: In the present invention, the sheet thickness is not limited to a specific range. However, if it is less than 0.22 mm, automatic caulking cannot be performed and the space factor is significantly reduced, and if it exceeds 0.42 mm, high-frequency iron loss significantly increases. In the preferred embodiment, the thickness is 0.22 to 0.42 mm.
[0026]
According to the present invention, a steel having the above composition is manufactured by hot rolling and, if necessary, cold rolling and then performing finish annealing. Hereinafter, the present invention will be described by taking the case of performing cold rolling as an example.
[0027]
First, at the time of hot rolling, the slab having the above components is reheated at a heating temperature of 1250 ° C. or less and finished into a hot rolled steel sheet having a thickness of 1.5 to 2.0 mm by a normal hot rolling method. When the heating temperature exceeds 1250 ° C., the magnetic properties deteriorate, so the temperature is set to 1250 ° C. or less, and preferably 1000 to 1150 ° C. to ensure rollability.
[0028]
After hot rolling, the hot-rolled sheet may be annealed to improve the magnetic properties in some cases. If the annealing temperature of the hot-rolled sheet is less than 600 ° C, there is no effect, and if it exceeds 1100 ° C, the crystal grains become excessively coarse, causing troubles such as fracture during cold rolling.
[0029]
The obtained hot-rolled sheet is then preferably cold-rolled to a thickness of 0.22 to 0.42 mm. In the case of cold-rolling, intermediate annealing at an intermediate thickness of 600 to 1000 ° C. is optionally performed. Finish annealing is performed by continuous annealing at 700 to 1100 ° C. If the final annealing temperature is less than 700 ° C, a sufficient recrystallization structure cannot be obtained, resulting in poor magnetic properties. If the temperature exceeds 1100 ° C, the crystal grains become extremely coarse and the workability deteriorates.
[0030]
The steel sheet obtained by cold rolling should have a surface roughness of 0.5 μm or less. Surface roughness: When Ra exceeds 0.5 μm, the space factor decreases significantly.
After finish annealing, a surface coating layer made of only a resin or a mixture of a resin and an inorganic binder may be applied to the steel sheet surface in some cases. It is sufficient to use a conventional surface coating as it is, and there is no particular limitation even in the present invention.
[0031]
【Example】
[Example 1]
Steels having the steel compositions shown in Table 1 were melted, and slabs having a thickness of 227 mm and a width of 1000 mm were cast therefrom and charged into a heating furnace. In this heating furnace, it was reheated to the temperature shown in Table 1 and then subjected to normal hot rolling to finish a hot rolled coil having a thickness of 2.0 mm. This hot-rolled coil was subjected to normal pickling, and then cold-rolled with a cold rolling mill equipped with a work roll having a surface roughness (average surface roughness) of 0.8 μm to finish a cold-rolled coil. The plate thickness of the obtained cold-rolled coil was as shown in Table 1, and the surface roughness was as shown in Table 2.
[0032]
Next, continuous annealing was performed at the temperatures shown in Table 2, and after recrystallization finish annealing, a surface coating having a film thickness of 0.3 μm made of acrylic resin emulsion, magnesium chromate and boric acid was formed on the surface of the steel sheet by a roll coater method. .
With respect to the non-oriented electrical steel sheet thus manufactured, the magnetic properties, automatic caulking properties, and space factor were determined.
[0033]
First, for magnetic properties, the 25cm Epstein frame specified in JIS C2550 is used, and the iron loss from 100 Hz to 1 kHz at a carrier frequency of 3 kHz is cut at 750 ° C for 2 hours while being cut (full process). It was evaluated after the strain relief annealing (semi-process).
[0034]
As for automatic caulking, a ring core (4-point caulking) with an outer diameter of 45 mm and an inner diameter of 33 mm was prepared using an automatic caulking die manufactured by Kuroda Seiko, and the binding force was measured by a tensile test to obtain the caulking strength per point.
[0035]
The space factor was evaluated by the method defined in JIS C 2550.
As magnetic characteristics, W15 / 50 was less than 4.5 W / kg, W15 / 400 was less than 80 W / kg, and W10 / 800 was less than 90 W / kg. The caulking strength per point was 10 MPa or more, and the space factor was 96% or more.
[0036]
The results obtained are summarized in Table 2.
1 and 2 collectively show these results and a series of similar experimental results in a graph.
[0037]
Fig. 1 is a graph showing the relationship between [Mn] and [Si] + [Al]. In the figure, [x] indicates the case of fracture by cold rolling, and [△] indicates the space factor is 96%. Less than, [○] indicates W _15/50 is 4.5 W / kg or more, and [□] indicates W _10/800 is 90 W / kg or more. [●] is an example of the present invention.
[0038]
FIG. 2 shows the relationship between the plate thickness and iron loss (W _10/800 ). In the figure, [O] is the case of [Si] + [Al] +0.5 [Mn] <1.5. In all other cases, 1.5 <[Si] + [Al] +0.5 [Mn] ≦ 5.5 is satisfied.
[0039]
[Table 1]

[0040]
[Table 2]

[0041]
【The invention's effect】
Thus, in the past, automatic caulking was not possible with a thin non-oriented electrical steel sheet having a thickness of 0.50 mm or less, but according to the present invention, automatic caulking was possible without reducing the space factor. The practical value of the present invention is great, such as enabling mass production using a material excellent in high-frequency excitation characteristics, which is a problem today.
[Brief description of the drawings]
FIG. 1 is a graph showing the criticality of 1.5 <[Si] + [Al] +0.5 [Mn] ≦ 5.5 including the results of Examples.
FIG. 2 is a graph showing the relationship between sheet thickness and iron loss (W _10/800 ) including the results of Examples.

Claims (2)

% By weight
C: 0.01% or less, Si: 3.0% or less, Mn: 0.2 to 1.5%, S: 0.035% or less, sol. Al: 0.0005 to 2.5%, P: 0.005 to 0.15%, N: 0.005% or less,
However, 1.5 <[Si] + [Al] +0.5 [Mn] ≦ 3.5
It has a steel composition consisting of the balance Fe and inevitable impurities, has high-frequency excitation characteristics, and has an automatic caulking strength of 10 MPa or more per point, a space factor of 96% or more, a plate thickness of 0.22 to 0.33 mm, an average surface A non-oriented electrical steel sheet having a roughness Ra ≦ 0.5 μm. The steel having the steel composition according to claim 1 is heated to a temperature of 1250 ° C. or lower, hot-rolled, and further cold-rolled to obtain a cold sheet having a thickness of 0.22 to 0.33 mm. Non-oriented electrical steel sheet excellent in average surface roughness Ra ≦ 0.5 μm, high-frequency excitation characteristics, automatic caulking property, and space factor, characterized by performing finish annealing at a temperature of 700 to 1050 ° C. Manufacturing method.

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