JPS6187848A - High-tension soft-magnetic thin steel strip of fe-base alloy - Google Patents

Abstract

PURPOSE:To obtain a high-tension soft-magnetic thin steel strip of Fe-base alloy by subjecting the molten metal having a specific composition consisting of Si, Be, B, V, Nb, Ta, Zr, Hf, Cr, Cu, and the balance Fe to rapid cooling on the moving cooling body to be solidified. CONSTITUTION:The high-tension soft-magnetic thin steel strip of Fe-base alloy has a composition consisting of, by weight, 2.5-7.0% Si, >=1 kinds among 0.01-3.0% Be, 0.01-3.0% B, 0.05-5.0% V, 0.05-5.0% Nb, 0.05-5.0% Ta, 0.05-5.0% Zr, 0.05-5.0% Hf, 0.5-10.0% Cr, and 0.5-5.0% Cu, and the balance Fe with innevitable impurities, and can be obtained by continuously feeding the molten metal having the above composition onto the cooling body whose cooling surface is moving and sending its new surface successively, and by forcing the molten metal to be solidified by the rapid cooling. The above thin steel strip is a high-tension nonoriented silicon steel sheet having >=about 50kg/mm<2> tensile strength, >=about 1.5T magnetic flux density B50, and <=about 100w/kg iron loss W10/1,000.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a high tensile strength soft magnetic Fe-based alloy ribbon, and is particularly suitable for use in rotors of rotating machines and magnetic bearings. .

(Prior Art) In recent years, there have been remarkable developments in electrical and electronic equipment, including electronics, and one of the factors that further promotes such development is the increase in high-speed motion of rotating equipment. can.

BACKGROUND OF THE INVENTION Conventionally, rotors of commonly used motors are mainly made of laminated electromagnetic steel plates. The rotational speed of the rotor of such a motor is currently about 100,000 rpm or less at most, and high-grade non-oriented silicon steel sheet with excellent magnetic properties is mainly used as the electromagnetic steel sheet for the rotor material. It has been.

By the way, recently, with the demand for higher motor efficiency, it has become necessary to further increase the rotational speed of the motor, and the motor rotor must be able to rotate at 200,000 to 800,000 rpm or more. Numbers are now required. Therefore, there has been a need for materials for motor rotors that can withstand such high-speed bee movement.

In addition, when the motor is rotated at high speed, mechanical bearings suffer from significant wear, resulting in a significant decrease in motor efficiency and reliability. Recently, magnetic bearings have been devised, but since magnetic bearings in this case also constitute a kind of electric motor, the rotor of the magnetic bearing also has a rotation speed of 200,000 to 800,000 rpm, just like the motor rotor.
It is required to withstand high speed rotation.

In order to achieve high-speed rotation in such rotating equipment, the first issue is the development of materials that can withstand such high-speed rotation. In other words, the rotation speed of the rotating equipment rotor is 20~
This is because if the speed is increased to 800,000 rpm, the centrifugal force applied to the rotor will greatly increase compared to the conventional material, and there is a high risk that the rotor will collapse using the current materials.

For example, if we consider the case where a disk with an inner diameter R□ and an outer diameter R8 as shown in Fig. 4 is rotated, any part of the disk will have
A normal stress Fr in the radial direction and a normal stress Ft in the tangential direction act, and the maximum value of these stresses is simply expressed by the following equation.

However, W: Weight of the material ω: Angular velocity C: Boisson's ratio g: Acceleration of gravity Here, when comparing ('t) IIlaX and (Fr) maX, (Ft) AE is always better than (Fr) AE. Because of the large size, the rotating disk needs to have a tensile strength that is always larger than the circumferential stress ('t)max.

Also, as is clear from the above formula, the stress applied to the disk is
It is proportional to the square of the outer diameter and the square of the rotational speed. Therefore, as the rotational speed increases, the stress applied to the rotor becomes significantly larger, and when the rotor is used at a high rotational speed of 200,000 to 300,000 rpm, it is necessary to rotate the rotor in order to prevent damage to the rotor. sometimes 100 kg/la for child materials”
A high tensile strength exceeding .

By the way, as a general method for increasing the mechanical strength of iron-based materials, there are methods shown in Table 1 below.

Table 1 Among these methods, the solid solution strengthening method or grain refinement strengthening method is considered to be the most suitable method for strengthening electrical steel sheets because they do not impair magnetic properties or deteriorate toughness. The solid solution strengthening method takes advantage of the fact that the crystal lattice is distorted by solid solution of alloying elements, which increases the resistance to dislocation movement and makes the steel 9. This method strengthens steel by increasing the number of grain boundaries through grain refinement and hindering the movement of dislocations by the grain boundaries.

On the other hand, the magnetic materials used in the rotors of motors and magnetic bearings must be magnetically soft materials, that is, soft magnetic materials, and their characteristics include excellent soft magnetic properties. In this case, it is important that domain wall movement is easy, the excitation characteristics expressed by magnetic flux density are excellent, and the iron loss value is low. In addition, the rotor, especially when rotating at high speed, has excellent high frequency characteristics. This is required. Here, the relationship between the rotation speed N and the frequency if in the motor is expressed by the following equation.

f=N-P/120 (1-8) where P: motor minute, S: slip As understood from this equation, the rotation speed is 200,000 to 800,000 r.
In the case of pm, a soft magnetic material is required that has a low iron loss value in a high frequency range of several kHz to several tens of kHz.

(Problems to be Solved by the Invention) However, soft magnetic properties are usually at odds with mechanical strength. In other words, in general, in order to improve soft magnetic properties, magnetic increase movement is achieved by increasing the crystal grain size and reducing the number of dislocations, precipitates, inclusions, etc., thereby minimizing obstacles to domain wall movement. In terms of mechanical properties, making it easier has resulted in a decrease in strength and tensile strength.

For this reason, it has conventionally been considered difficult to obtain a soft magnetic material with good soft magnetic properties and high tensile strength.

This invention advantageously solves the above-mentioned problems, and is made of a material that not only has high tensile strength but also has excellent soft magnetic properties such as low high-frequency iron loss and low coercive force, specifically tensile crab 50. kg7W or more, and magnetic flux density B: 1.5
The purpose of the present invention is to propose a method for manufacturing a high tensile strength non-directional external power plate that satisfies the following: T or more and iron loss WIO/1000: 100sO W/''9 or less.

(Means for Solving the Problems) This invention was developed as a result of reconsidering the various strengthening methods shown in Item 1 above, and among the strengthening methods, the solid solution strengthening method has a negative impact on magnetic properties. This is based on the new knowledge that the magnetic properties are relatively small and that the deterioration in magnetic properties caused by such a strengthening method can be sufficiently compensated for by making improvements to the manufacturing process.

In order to achieve the above object, the inventors conducted extensive experiments and studies, and found that the molten metal was continuously supplied onto a cooling body in which the cooling ml was updated and moved at a high speed, forcing the molten metal to rapidly solidify. In addition to utilizing the so-called liquid quenching method to make thin strips,
It was discovered that the intended purpose could be advantageously achieved by adjusting the component composition of the ribbon as described below, and the present invention was completed.

That is, the present invention provides an F6-based alloy ribbon obtained by a liquid quenching method, the composition of which is Si! L5~7.0wt
% (hereinafter simply indicated by scratches), and Be: 0.01~
3.0%, B: 0.01-8.0%, V:
0.05-5.0%, Nb! 0.05-5.0%
, Ta: 0.05-5.0, Zr + 0.05
~5.0%, Hf! 0.05-5.0゛゛゛, O
r: 0.5-10.0% and Ou 20.5-
It is characterized in that it contains one or more selected from among 5.0 and 5.0, and the remainder consists of ye and unavoidable impurities.

This invention will be explained in detail below! Ru.

The alloy ribbon according to the present invention is produced by the liquid quenching method as described above, and the effects of the rapid solidification itself include l) expansion of the solid solubility limit, m) reduction of simultaneous segregation of M, and 8) crystallization. In addition to features such as the miniaturization of Higashi 1 weaving, the effects of direct sheet manufacturing using the liquid quenching method include: 4) [1 Processed materials can be directly manufactured into thin sheets5) (100
)<ovv) It has features not found in the conventional melting-casting-rolling method, such as oriented texture catechylation, and it is especially suitable for producing high tensile strength soft magnetic materials for rotors.
), 4) and 6) contribute particularly effectively. In other words, even if elements that improve tensile strength are dissolved in iron at room temperature, their precipitation can be suppressed by liquid quenching. As such, it is required that the axis of easy magnetization points in all directions within the plate mJ,
As mentioned in 6) above, the quenched ribbon is left as it is (100
)<0VW) structure is obtained, which is extremely advantageous for the rotor material. Furthermore, when trying to achieve high tensile strength, the material becomes hard and brittle, which often significantly deteriorates workability. It is possible to directly manufacture thin plates even without it, and this is advantageous in achieving high tensile deterioration in motor rotor materials that are used by laminating thin plates.

From the above-mentioned viewpoint, the inventors decided to adopt the liquid quenching direct plate manufacturing method in this invention.
The following experiments were conducted regarding the alloy composition of a soft magnetic ye-base alloy ribbon produced by the liquid quenching method. First, an alloy containing electrolytic iron and 81 and B in various proportions was melted, and the alloy was melted. The hot water was rapidly cooled and solidified by continuously supplying the hot water from its injection nozzle to the contact area of twin rolls rotating at high speed. Obtained 100-2
FIG. 1 shows the results of measuring the tensile strength of a thin strip sample with a thickness of 00 μm using the Instron test.

As is clear from the figure, it can be seen that the tensile strength is reliably improved by adding B to iron containing Sl. Even without adding B, a high tensile strength of 70ψ-3 or more can be obtained by containing Sl of 6.5 coefficient or more, but in this case, the material becomes brittle, which is a significant disadvantage in use. Therefore, it is necessary to reduce the 81 content and compensate for it with B to improve the brittleness and thereby increase the tensile strength.

The inventors then determined %4. filSi-F8 alloy contains Be, VsNb, Ta in various proportions as well as B.
, Zr.

The tensile strength of a quenched ribbon prepared in the same manner as in the above experiment with addition of 11f, Or and Qu was investigated. The results are shown in FIG.

As is clear from the figure, the tensile strength was improved by adding each of the above-mentioned elements.

Furthermore, the inventors added B j Be I V e Nb I Ta I in various proportions to the 4.5% Si-Fe alloy.
Iron loss WIO/100 when each ribbon is annealed at 950°C in hydrogen after adding Zr # Hf l Or and O and forming a quenched ribbon in the same manner as above.
I complained about G.

The results are summarized in FIG. 8.

As is clear from the figure, the iron loss value deteriorated as the amount of these elements added increased.

Although this is a significant improvement compared to the conventional method, adding large amounts of these elements leads to deterioration of iron loss, so even if the amount of addition of such elements is to improve tensile strength, it is not enough to reduce iron loss. It is important to consider the impact when setting.

(Function) Next, the reason why the component composition range is limited as described above in this invention will be explained.

Si! 2.5-7.0 If the Si content is less than 2.5%, α → r phase transformation will occur, and the electrical resistance will decrease, leading to deterioration of electromagnetic properties. Not only does it become extremely brittle and yield and productivity deteriorate, but also the saturation magnetic flux density decreases. Therefore, the content of Sl was limited to a range of 2.5 to 7.0%.

B, Be: 0.01-8. OtlbB and B
If the content of e is less than 0.011, the effect of improving tensile strength is poor, while if it exceeds 8.0, the magnetic properties tend to deteriorate, so it is limited to a range of 0.01 to 8.0.

V z Nbe Ta e Zr, Hf I 0.
05-5.0%V, Nb#Ta, Zr, and Hf all have a poor tensile strength improvement effect when the content is less than 0.05%, whereas when the content exceeds 5.0%, inclusions and precipitates are formed. is likely to be generated, leading to deterioration of the magnetic properties, so each is limited to a range H of 0.05 to 5.0.

Or: 0.15 to 10.0% If the Qr content is less than 0.5%, the desired tensile strength improvement effect can be expected, but if it exceeds 10.0%, the saturation magnetic flux density deteriorates. Since the ratio was significant, it was limited to a range of 0.5 to 10.0.

Ou 40.5-5.0% If the Ou content is less than 0.5'1, the effect of improving tensile strength will be small, while if it exceeds 5.0%, the zero-temperature properties will deteriorate. It was limited to a range of 0%.

Although the above description has mainly been made regarding the case where they are added alone, two or more types may be added in combination as long as they are within the above component composition range. However, when adding too much in combination, the magnetic properties deteriorate, so it is desirable that the total amount is 18.0% or less.

Next, this invention 1! ! I will explain how to send it.

First, a molten alloy having the above-mentioned preferred composition is quenched and solidified into a thin ribbon by a liquid quenching method such as a twin roll method, a single roll method, or a belt method. At this time, it is desirable that the temperature of the molten alloy is 50° C. or more higher than the melting temperature. This is because if the temperature is less than (melting temperature + 50°C), the molten metal will be cooled and solidified in the nozzle, causing nozzle clogging, and as a result, there is a risk that continuous production of rotten zones will not be possible. be.

The quenched ribbon obtained as described above can of course be used as it is as a magnetic material for motor rotors, etc., but in order to further improve the magnetic properties, it is necessary to It is effective to perform an appropriate heat treatment, for example, annealing at a temperature of 700° C. or higher, preferably 900° C. or higher, for a short time of about 80 seconds to 60 minutes.

In Figure 5, ゛ Ichi B Ichiban 95
%Si--Fe alloy ribbons are annealed at various temperatures, and the results are shown for the ratio between the annealing temperature and the iron loss WIG/1000.

As is clear from the figure, in the alloys mentioned above, the iron loss value decreases as the annealing temperature increases, especially at 900°C.
The effect was remarkable.

The reason why the magnetic properties are improved by annealing the thin ribbon after quenching is that the grain size of the crystal grains becomes coarser due to annealing, and the coarsened crystal grains have a (100) <ovw). Therefore, it can be said that performing such annealing makes more effective use of the features of the liquid quenching method.

The high tensile strength soft magnetic material thus obtained has an electrical resistance of 7.
Since it is as high as 0 to 90 g, when used at commercial frequencies, there is no problem even if it is used in a stacked state, but when used at high frequencies, it is necessary to insulate the surface. This is because when a magnetic material is used in a high frequency range, eddy current loss increases significantly compared to when it is used in a normal commercial frequency range. In this case, it is advantageous for high frequency characteristics to use magnetic steel sheets laminated as thin materials, but if the insulation between each layer is insufficient, the plates will come into contact with each other and the effect of laminating thin plates will be reduced. It will be lost. In other words, this is the same as operating a thick plate in a high frequency range, and the magnetic properties deteriorate. Therefore, in actual use, it is important to coat the surface with an insulating coating that has excellent adhesion.

In addition, when applying the quenched ribbon according to the present invention to an actual machine, after punching it into the shape of a motor core, etc., it is subjected to strain relief annealing at a temperature of about 700 to 800 degrees Celsius in order to remove the strain caused by punching. This is desirable.

(Example) Example 1 Hot water at 1600°C having a composition of 1 tla B -4.5% 5i-Fe was injected into the contact area of a twin plate rotating at high speed to form a quenched thin plate with a thickness of 90 μm. It was made into an obi.

Table 2 below shows the results of examining the core loss WIO/1000 and tensile strength δT of the obtained quenched ribbon and the subsequent annealing treatment.

Table 2 Example 3 4.5 Be
.

Hf s V z 'I'a, Nb, Zr,
The molten metal to which 1% of each of Ou and Hcr, T, and T-T were added was injected into the contact area of twin rolls rotating at high speed to form a quenched ribbon with thicknesses of go and gm.

Table 8 below summarizes the results of iron loss Wlo/1G00 and tensile strength δT after each of the obtained ribbons was annealed at 1000°C. A similar investigation was conducted for the composition of the ribbon, and the obtained results are also listed in Table 8 as a comparative example.

Table 8 (Effects of the Invention) Thus, according to the present invention, the tensile strength can be significantly improved without substantially deteriorating the iron loss characteristics.

[Brief explanation of drawings]

Figure 1 is a graph showing the influence of Si and B in steel on tensile strength. Figure 2 is a graph showing the influence of the eighth additive element on tensile strength. Figure 8 is a graph showing the influence of the eighth additive element on tensile strength. A graph showing the influence on iron loss. Figure 4 is a plan view of a disk with an inner diameter of R1 and an outer diameter of R8. Figure 6 is a graph showing the influence on iron loss.
It is a graph showing the relationship between annealing temperature and iron loss of a 1%B-4,5%Si-Fe alloy. Figure 1 Si (wt%) in Fe Figure 2! Sword n yuan t (wt%) Figure 3 Seito sword 0 yuan 1 t (wt%J

Claims (1)

[Claims] 1. Si: 2.5 to 7.0 wt%, Be: 0.01 to 3.0 wt%, B: 0.01 to 3.0 wt%, V: 0.05 to 5. 0wt% Nb: 0.05-5.0wt% Ta: 0.05-5.0wt% Zr: 0.05-5.0wt% Hf: 0.05-5.0wt% Cr: 0.6-10. 0 wt% and Cu: 0.5 to 5.0 wt%, and the remainder is Fe and unavoidable impurities. A high tensile strength soft magnetic Fe-based alloy ribbon obtained by continuously supplying a molten metal having a composition within a range onto a cooling body whose cooling surface renews and moves at high speed, and forcing the molten metal to rapidly solidify.