JP4018790B2 - Non-oriented electrical steel sheet for high frequency and manufacturing method thereof - Google Patents

Description

【００３７】
Ｃｒ添加でＡｌ，Ｓｉ量との交互作用効果も手伝って優れた固有抵抗が得られた。また、高周波鉄損と磁束密度は、更に、Ｓｉ，Ａｌ，Ｓ，Ｔｉ，Ｎｂを本発明範囲に制御したもので良好なものを得た。
【００３８】
［実施例２］
実施例１の実験No. ７の５．４％Ｃｒ冷延板を用いて、焼鈍の温度を水素中で変えて結晶粒径を制御した。なお、均熱時間は２０秒とした。次いで、クロム酸とエポキシ樹脂混合被膜を焼き付けして、表２に示す結果を得た。
【００３９】
【表２】

【００４０】
表２に示すように、製品の結晶粒径が本発明範囲で、優れた高周波鉄損と磁束密度が得られた。
【００４１】
【発明の効果】
以上の如く、少ないＣｒ量を利用して、優れた高周波鉄損と磁束密度を有する高周波用途に優れた無方向性電磁鋼板を提供することができた。[0001]
BACKGROUND OF THE INVENTION
The present invention provides high-grade grades of non-oriented electrical steel sheets, particularly motor core materials having excellent specific resistance used at high frequencies, and a method for producing the same.
[0002]
[Prior art]
From the viewpoint of the global environment, the negative effects of recent energy-intensive civilizations are regarded as problems. For this reason, in the field of electrical equipment in which non-oriented electrical steel sheets are used, further reduction in power consumption is required for motors for air conditioning equipment, main motors for electric vehicles, stepping motors for high-speed printers, and the like. . In addition, since variable speed motors ranging from low frequency to high frequency by inverter control instead of conventional ON-OFF control are becoming more and more, excellent electrical steel sheets have been required over a wide frequency range. It was.
[0003]
Conventional non-oriented electrical steel sheet manufacturing technologies include increasing Si and Al to increase electrical resistance (hereinafter referred to as “specific resistance”) for the purpose of improving high-frequency iron loss. Thinning has been done. However, the problem was the brittleness of the steel sheet due to the large amount of Si + Al. That is, particularly in winter, production obstacles such as cracking at a location where bending deformation of the steel sheet after hot-rolled sheet annealing is applied, and breaking at a cold-rolled mill are very important problems. For this reason, effective elements other than Si and Al have been studied, but have not been put to practical use.
[0004]
For example, there is a technology that focuses on Cr. In chronological order, US Pat. No. 3,615,367 proposes an iron loss core with excellent corrosion resistance by 9-20% Cr-0.01-3% Si and / or Al-Fe. Yes. However, it is a problem that Ti ≧ 0.02% is essential. Ti is a very harmful element for greatly increasing iron loss, particularly hysteresis loss, in the investigation by the present inventors, and the iron loss value at high frequency was not sufficient in the component system described in this publication.
[0005]
Japanese Examined Patent Publication No. 39-20644 proposes a corrosion-resistant soft magnetic material of 11.5 to 20% Cr-1 to 6% Si and / or 0.5 to 5% Ti—Fe. However, since this steel is a component system that does not contain Al, high-frequency magnetic properties are not sufficient, and expensive steel such as Ni, Co, and Mo is included, and thus there is a problem that the manufacturing cost is increased.
[0006]
Japanese Patent Publication No. 50-37135 proposes 8-18% Cr-0.3-0.75% Si-Fe as a technique focusing only on the corrosion resistance of Cr. Japanese Patent Publication No. 51-1646 proposes an 8-18% Cr-0.3-0.75% Si-Fe-based stainless steel sheet. Japanese Patent Publication No. 56-15705 discloses a method for producing a weather-resistant electrical steel sheet of 1 to 5.5% Cr-1 to 3.5% Si-Fe. However, since none of these three cases contains Al, the high-frequency magnetic characteristics are not sufficient.
[0007]
On the other hand, a method for producing a 5.5 to 11.5% Cr-1.5 to 3.5% Si-0 to 1% Al-Fe-based high-hardness corrosion-resistant electrical steel sheet in Japanese Patent Publication No. 2-38646, A manufacturing method by rapid solidification of a 4-13% Cr-2-4% Si-0-2% Al-Fe-based corrosion-resistant electrical steel sheet in Kaihei 5-295437, the same 4 in JP-A-7-26324 -13% Cr-2-4% Si-0-2% Al-Fe-based corrosion-resistant electrical steel sheet produced by rapid solidification of the three inventions, etc., all have high frequency because the crystal grain size in the product is large The magnetic properties were not sufficient.
[0008]
All of the above-mentioned patents are limited to special applications such as electromagnetic switches (magnet switches) from the viewpoint of corrosion resistance, and have not been focused on high-frequency applications.
[0009]
As a technique paying attention to the specific resistance of Cr, there is one described in JP-A-8-47235. This technique relates to a material for a stepping motor using a high electric resistance of 9% or more of high Cr. However, Ti, which is essential for stabilizing the ferrite phase in this material, is a very harmful element for greatly increasing iron loss, particularly hysteresis loss, in our investigation. In the component system, the iron loss value at high frequency was not sufficient.
[0010]
It has been known that a so-called electrothermal material having a specific resistance of about 20 to 26% Cr-Al-Si-Mn-Fe based on 120 to 150 μΩ-cm has been known for a long time. Although there is description in 2520 (1986), it seems that it was not investigated regarding the iron loss and magnetic flux density as the electromagnetic steel plate. In the prior art described above, most of the component systems have a Cr content of 5.5% or more, and the reduction in magnetic flux density and the addition cost are problems.
[0011]
[Problems to be solved by the invention]
In view of the above points, the present invention provides a non-oriented electrical steel sheet excellent in high-frequency applications having excellent high-frequency iron loss and magnetic flux density by utilizing a small amount of Cr.
[0012]
[Means for Solving the Problems]
The present invention is as follows.
(1) in mass%,
C ≦ 0.005%, Cr: 3.0 to 5.5%,
Si: 0.5-4%, Al: 0.1-5%
Mn ≦ 3%, P ≦ 0.3%,
S ≦ 0.005%, N ≦ 0.005%,
Ti ≦ 0.008 %, Nb ≦ 0.008 %
The balance is composed of Fe and inevitable impurities, and the ferrite average crystal grain size is 10 to 170 μm.
[0013]
(2) mass%,
C ≦ 0.005%, Cr: 3.0 to 5.5%,
Si: 0.5-4%, Al: 0.1-5%
Mn ≦ 3%, P ≦ 0.3%,
S ≦ 0.005%, N ≦ 0.005%,
Ti ≦ 0.008 %, Nb ≦ 0.008 %
High-temperature non-directional, characterized in that the hot-rolled sheet comprising Fe and the inevitable impurities is annealed and then cold-rolled and then subjected to continuous annealing to make the average grain size of ferrite to 10 to 170 μm Method for producing an electrical steel sheet.
[0014]
The points of the present invention are the following three points.
(1): By grasping the relationship between the Cr content, Al content, Si content and the specific resistance value of the steel sheet more accurately than in the past, the combination of Cr, Al and Si is low Cr. A component system with a high specific resistance was realized.
{Circle around (2)} Ti, S, N, etc. often used in high Cr stainless steel sheets were avoided because they deteriorate the high frequency characteristics of the electromagnetic steel sheets.
(3): Even when Cr is added, brittle fracture is less likely to occur compared to conventional Si or Al steel.
[0015]
The relationship between Cr, Al, Si and the specific resistance in (1) will be described in detail below.
In the range of weight ratio Si ≤ 4%, Al ≤ 5%, Mn ≤ 3%, Cr ≤ 15%, 21 vacuum melted ingots with different components were manufactured, and then hot rolled to measure the specific resistance. Then, a multiple regression analysis was performed, and the following result with a multiple correlation coefficient of 0.98 was obtained.
ρ (μΩ-cm) = 19.3 + 2.7Cr + 14.2Si + 11.9Al + 0.7Cr × Al + 0.2Cr × Si
[0016]
That is, Si and Al have a large effect of improving the specific resistance as conventionally known, but Cr alone has a small effect of improving the specific resistance. In addition, it was found that the interaction between the amount of Al and the amount of Al particularly exists in Cr, and the integrated value of the amount of Cr and the amount of Al greatly contributes to the resistivity. Note that the integrated value with the Cr amount contributes to the specific resistance although the Si amount is also slight.
[0017]
In addition, the formula which gives the conventional specific resistance was the following which is supposed to be in the catalog of US Steel.
ρ (μΩ-cm) = 10.45 + 6.0C + 11.6Si + 13.2Al + 4.5Mn + 13.7P + 10.4S
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
First, the component system of the steel of the present invention will be described.
The C content is 0.005% or less. The reason is that if the amount of C exceeds this value, there is a problem in magnetic aging.
[0019]
The amount of Cr is 3.0 to 5.5%. As described above, Cr is effective by increasing the specific resistance by itself or by interaction with Al or Si. If the content is less than 3.0 %, the improvement in specific resistance is small, and if it exceeds 5.5%, the deterioration of the magnetic flux density is increased and the addition cost is increased. For this reason, the Cr content is set to 3.0 to 5.5%.
[0020]
The amount of Si is 0.5 to 4%. If the amount of Si is large, the specific resistance increases and the iron loss decreases. However, if it is less than 0.5%, αγ transformation occurs during hot rolling or annealing, and the magnetic properties deteriorate. Therefore, the amount of Si is set to 0.5 to 4%.
[0021]
The Al content is 0.1 to 5%. Al also increases the specific resistance and decreases the iron loss. However, if the Al amount is less than 0.1%, the iron loss is not sufficiently reduced, and if it exceeds 5%, a problem occurs in brittleness. ˜5%.
[0022]
The amount of Mn is 3% or less. Mn also increases the specific resistance and decreases the iron loss, but if it exceeds 3%, a problem arises in brittleness, so the content is made 3% or less.
[0023]
The amount of P is 0.3% or less. P also increases the specific resistance and decreases the iron loss. However, if it exceeds 0.3%, a brittleness problem occurs.
[0024]
The S amount is 0.005% or less. If the amount of S exceeds 0.005%, sulfides such as MnS increase, which inhibits domain wall movement in the product and deteriorates the magnetic properties, so the content is made 0.005% or less.
[0025]
The N amount is 0.005% or less. This is because if the N content exceeds 0.005%, blister-like surface defects called blisters are generated.
[0026]
The Ti content is 0.008 % or less. Ti forms nitrides, sulfides, oxides, carbides, or a composite thereof to deteriorate the magnetic properties. The limit is 0.008 %.
[0027]
The Nb content is 0.008 % or less. Nb also forms nitrides, sulfides, oxides, carbides or their composites to deteriorate the magnetic properties, but its limit is 0.008 %.
[0029]
Hot rolling slab heating is not particularly limited, but a low temperature is good for the purpose of preventing fine precipitates, and 950 to 1200 ° C. is preferable. Next, normal hot rolling is performed, but the thickness of the hot rolled sheet may be 0.8 to 3.0 mm.
[0030]
Next, the hot-rolled sheet obtained by hot rolling is annealed. When the hot-rolled sheet is annealed, the magnetic flux density is improved and the hysteresis loss can be reduced. Therefore, the iron loss is particularly excellent at a low frequency (300 Hz or less). The conventional annealing temperature of the hot-rolled sheet is preferably 700 to 1200 ° C.
[0031]
Pickling is performed before or after hot-rolled sheet annealing, followed by cold rolling. Cold rolling is performed by ordinary levers or tandem, but levers such as Sendzimer mill are preferable because a high magnetic flux density can be obtained as is known. As is well known, warm rolling at a temperature of 100 to 300 ° C. is also preferable because the magnetic flux density is improved. The plate thickness is preferably thin for improving high-frequency magnetic characteristics, and preferably 0.1 to 0.6 mm.
[0032]
After cold rolling, it is degreased and subjected to continuous annealing. The annealing temperature is preferably a high temperature of 700 ° C. or higher, and it is particularly necessary to control the crystal grain size to 10 to 170 μm. If the crystal grain size is less than 10 μm, the iron loss of the steel sheet cannot be sufficiently reduced, and if the crystal grain size exceeds 170 μm, the magnetic flux density of the steel sheet is deteriorated. The crystal structure having a crystal grain size in such a range needs to be a ferrite structure. This is because high-frequency iron loss deteriorates in the transformed structure. The temperature condition for continuous annealing varies depending on the components and time, but for example, the temperature range is 650 to 1150 ° C. for 20 seconds of soaking. Moreover, in this continuous annealing, in order to prevent the deterioration of the high magnetic field iron loss due to the surface oxidation of the steel sheet, a reducing atmosphere of a mixture of hydrogen and nitrogen is preferable as disclosed in JP-A-56-16623.
[0033]
After the continuous annealing as described above, usually, a mixture of organic and inorganic materials, an all-organic or inorganic insulating coating is applied and baked. On the other hand, there are non-oriented electrical steel sheets that are not laminated depending on the product used. In such a case, the steel sheets are shipped as they are. In some cases, anti-rust oil is applied to prevent rust.
[0034]
Although it is possible to repeatedly produce cold rolling and annealing several times as in the prior art, it is disadvantageous in terms of cost.
[0035]
【Example】
Examples of the present invention will be described below.
[Example 1]
A steel ingot with various components changed and fixed at 0.001% by vacuum melting was hot rolled at a heating temperature of 1000 ° C. to obtain a 2.5 mm thick hot rolled sheet. Then, after annealing in nitrogen at 1000 ° C. for 30 seconds, pickling and cold rolling in tandem to obtain a cold rolled steel sheet having a thickness of 0.35 mm. This cold-rolled steel sheet is subjected to continuous annealing at 850 to 950 ° C. for 10 seconds so that all the average crystal grain sizes are aligned to 50 to 60 μm, and an organic (epoxy resin) and inorganic (magnesium hydroxide and chromic acid) mixed film After the coating 1 g / m ² was baked at 300 ° C., the specific resistance and the high frequency magnetic properties were measured. The magnetism was measured according to JIS C 2550 with an Epstein apparatus. The results are shown in Table 1.
[0036]
[Table 1]

[0037]
By adding Cr , the interaction effect with Al and Si contents was also helped, and an excellent specific resistance was obtained. Further, high-frequency iron loss and magnetic flux density were obtained by further controlling Si, Al, S, Ti, and Nb within the scope of the present invention.
[0038]
[Example 2]
Using the 5.4% Cr cold-rolled sheet of Experiment No. 7 in Example 1, the annealing temperature was changed in hydrogen to control the crystal grain size. The soaking time was 20 seconds. Next, the mixed film of chromic acid and epoxy resin was baked to obtain the results shown in Table 2.
[0039]
[Table 2]

[0040]
As shown in Table 2, the crystal grain size of the product was within the range of the present invention, and excellent high frequency iron loss and magnetic flux density were obtained.
[0041]
【The invention's effect】
As described above, a non-oriented electrical steel sheet excellent in high frequency applications having excellent high frequency iron loss and magnetic flux density can be provided by using a small amount of Cr.

Claims (2)

In mass%,
C ≦ 0.005%,
Cr: 3.0 to 5.5%,
Si: 0.5-4%
Al: 0.1 to 5%,
Mn ≦ 3%,
P ≦ 0.3%,
S ≦ 0.005%,
N ≦ 0.005%,
Ti ≦ 0.008 %,
Nb ≦ 0.008 %
The balance is composed of Fe and inevitable impurities, and the ferrite average crystal grain size is 10 to 170 μm. In mass%,
C ≦ 0.005%,
Cr: 3.0 to 5.5%,
Si: 0.5-4%
Al: 0.1 to 5%,
Mn ≦ 3%,
P ≦ 0.3%,
S ≦ 0.005%,
N ≦ 0.005%,
Ti ≦ 0.008 %,
Nb ≦ 0.008 %
High-temperature non-directional, characterized in that the hot-rolled sheet comprising Fe and the inevitable impurities is annealed and then cold-rolled and then subjected to continuous annealing to make the average grain size of ferrite to 10 to 170 μm Method for producing an electrical steel sheet.