KR970004566B1 - Soft magnetic steel material - Google Patents

Abstract

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Description

Ferromagnetic Magnetic Steels

DC electromagnet core materials, or magnetic shielding materials such as medical devices, various physical devices, electronic parts, and devices, which are particularly prominent in recent years and are widely used, are made of wrought iron, pure iron, and extremely expensive Fermaloy and supermalley. have. By the way, a magnetic flux density (hereinafter referred to as B ₁ value) is typically about 3000 ~ 11000G of the 10e of the soft iron or pure iron, these MRI can, such as a magnetic shielding (nucleons have a single-layer phase-up diagnostic apparatus according to the resonance) to the Gaussian degree It is used as a magnetic shielding material or as an electromagnet core material.

Among the applications in which the direct current magnetization characteristic becomes important, the problem of the prior art is indicated by using magnetic shield as an example. In other words, pure MRI is used for the magnetic shielding of Hyundai MRI, which is relatively inexpensive and has high saturation magnetization. Even JIS 2504 SUYPO) defines the lower limit of the B ₁ value as 8000 G. In this characteristic, magnetic shielding about the geomagnetism is difficult, and in addition, the shielding system for magnetic shielding of about several Gauss or less is caused. In some cases, Fe-Ni alloys such as Fermaloy or Supermaloy may be used as a shielding material for better shielding. However, these materials can be shielded to a level below geomagnetism, but are extremely expensive and have saturation magnetization. Compared with this, it is lower than 1/3 to 2/3, and therefore, there is a drawback that the thickness must be increased to the extreme in shielding the high magnetic field. Therefore, it is economically difficult to use a large amount in any case.

In view of the above situation, several studies have already been made to increase the permeability without damaging the high saturation of pure iron-based materials. For example, none of the methods disclosed in Japanese Patent Application No. 63-45443, Japanese Patent Application No. 62-77420, or Japanese Metal Society No. 23, No. 5 (published in 1984) "Development of Extreme Electromagnetic Steel Sheets" Although this technique is intended to improve the magnetic permeability, these techniques are limited to hot-rolled sheets having a relatively thin plate thickness or magnetic flux density at 0.5 Oe when stricter DC magnetization characteristics such as Al ₂ O ₃ are evaluated. B0.5 value) is not a technology that can achieve more than 11000G, any of which is not sufficient as a technique for obtaining the DC magnetization characteristics.

In such a phenomenon, there is no material having a high permeability, that is, high saturation magnetization and low magnetic flux density with a low magnetic field corresponding to the degree of geomagnetism. It is an object of the present invention to provide such a material.

Disclosure of the Invention

In order to solve the above-mentioned problems, the present inventors first examined industrial pure iron, which is the basis of soft magnetic materials for direct current magnetic fields, clarified its shortcomings, and conducted studies to improve the characteristics, and obtained the following findings.

That is, from the viewpoint of obtaining a high permeability, the addition of Al (1) enables effective deoxidation, leading to improvement in permeability resulting from the reduction of oxygen content and oxide inclusions, as well as the formation of solid-solution N having a negative effect on permeability. Can be reduced, and (2) addition of any necessary amount enables the agglomeration of finely dispersed AIN particles to be achieved, and the adverse effects of the AIN particles can be suppressed to an extremely low level. By annealing, which is a means of removing lattice strain, the effect of remarkably promoting the granulation of ferrite grains is also obtained, and all of them are effective for improving the permeability. (3) By adding more than 0.5 wt%, It is possible to remarkably increase the transformation temperature or to make the ferrite single phase, so that deformation due to transformation is not introduced. It is also possible to perform annealing at a temperature exceeding 900 ° C, and this annealing brings about effective removal of lattice deformation and coarsening of ferrite grains, and it is thought that the effect of improving Al permeability of solid solution Al is also considered. (4) In addition, by appropriately adding Ti as necessary, they fix the solid solution N first, contributing to the improvement of properties, and in particular, the effort to reduce the N content is not necessary. In addition, in view of maintaining a high saturation magnetization of the material, (5) addition of Al exceeding 2.5% should be avoided, and (6) lowering transformation temperature or necessary Al when the C and N content is large. In addition to the increase in the amount added, the properties may be deteriorated due to the increase in lattice strain due to the increase of the solid solution C and N, or the formation of carbides and nitrides. In order to avoid these problems, the present inventors have discovered that an upper limit of the amount of C and N exists, thereby completing the present invention.

In other words, the first invention of the present application is by weight, Al: 0.5-2.5%, Si: 1.0% or less, C + N: 0.007% or less, Mn: 0.5% or less, oxygen: 0.005% or less, balance of Fe and unavoidable impurities It is composed of a composition, and has a ferrite grain size of 0.5 mm or more and exhibits a magnetic flux density value of 11000 G or more at 0.5 Oe, a magnetic flux density value of 15500 G or more at 25 Oe, and a coercive force of 0.4 Oe or less in a state where the lattice strain is sufficiently removed. To provide ferromagnetic magnetic steels.

In addition, in the second invention of the present application, by weight%, Al: 0.5 to 2.5%, Si: 1.0% or less, C + N: 0.014% or less, Mn: 0.5% or less, oxygen: 0.005% or less, Ti: 0.005 to 1.0 %, Remainder Fe and unavoidable impurities, the ferrite grain size is 0.5 mm or more, and the magnetic flux density value at 0.5 Oe is 11000 G or more, the magnetic flux density value at 25 Oe is 15500 G or more, the coercive force in a state where the lattice strain is sufficiently removed. It is to provide a ferromagnetic magnetic steel material characterized in that the 0.4 Oe or less.

Hereinafter, the reason for limitation of the composition in this invention is demonstrated.

It is preferable to reduce C and N as much as possible in order to secure excellent DC magnetization characteristics, but in the case of industrial production, the extreme reduction is difficult, resulting in extreme cost increase. In addition, in order to increase the transformation temperature by addition of Al, if the addition amount of C and N is not kept low, there is a possibility that the required amount of Al will increase, which in turn leads to lowering the saturation magnetization, and thus the intention of the present invention. Against In FIG. 2, after the lattice strain is removed by annealing under normal conditions of 1000 to 1100 ° C, the change in the DC magnetization characteristics is captured as a change in B _0.5 value, and the influence of the amount of C + N is examined. According to this, it turns out that it is necessary to make C + N amount 0.007 weight% or less in order to acquire a favorable characteristic. For this reason, in this invention, it is set as C + N: 0.007 weight% or less.

In the present invention, Ti, which is a strong nitride generating element, is added as necessary as described later. Ti is added for the purpose of detecting the above-mentioned adverse effects of N without strictly defining the upper limit of the amount of N which leads to the increase in cost. Therefore, in this case, the upper limit of the amount of C + N is 0.014% by weight. do.

Although Si contributes to the improvement of permeability, in the present invention, coarse ferrite grains of 0.5 mm or more can be obtained after annealing by Al addition, in order to avoid lowering of saturation magnetization and cost increase by adding a large amount, the upper limit thereof is used. Was 1.0 wt%.

It is preferable to reduce Mn because it is an element that deteriorates the DC magnetization characteristic, but an extreme reduction causes a cost increase and an increase in N content. Moreover, since there is also an effect of preventing hot brittleness by fixing S, 0.5 wt% may be contained as an upper limit in the range which Mn / S does not fall below 10.

Al, as described above, is an important element of the present invention, which causes the fixation of solid-solution N, the coagulation of AIN particles, and the increase in transformation temperature, and coarsening and lattice of ferrite grains by annealing by enlarging the ferrite region. In order to reduce deformation and to further improve the direct magnetization characteristics of the solid solution Al itself, it is an element that must be added in order to obtain excellent direct magnetization characteristics. As shown in FIG. 1, the effect of Al is Sol. In a state of Al it is obtained by adding at least 0.5% by weight of the other hand, since undesirable and results in a reduced value B ₂₅ caused by the reduction in the saturation magnetization by the addition in excess of 2.5% by weight addition amount is the range of the Al Sol. It was 0.5 to 2.5 weight% in the state of Al.

As described above, Ti is a strong nitrate generating element, and the content of N is not sufficiently reduced by adding it in the range of 0.005 to 1.0% by weight, so that direct current magnetization characteristics are remarkable due to the fixing effect of solid solution N even in inexpensive materials. Damage can be avoided. In addition, when the N content is relatively low, since the amount of nitride particles is also small, a slight improvement in the DC magnetization characteristics can be expected. On the other hand, when it exceeds the said upper limit, the DC magnetization characteristic will be deteriorated.

As described above, by restricting the chemical component of the present invention, steel having a high B _0.5 value and a B ₂₅ value, that is, excellent soft magnetic characteristics in a DC magnetic field can be obtained.

The steels of the present invention as described above include hot-worked steels, cold or warm-worked steels, and also include steel plates, thin plates, wire materials (shaped steels, etc.), forgings, and the like as steel.

The steel materials of the present invention as described above are annealed between the method of hot working the cast steel, the method of hot or cold working as it is, the cold or hot working after hot working, the method of hot rolling directly, the processing of these methods (usually Although it can manufacture by various methods, such as the method of 450 degreeC or more), in either case, final annealing is performed. This final annealing is usually carried out at 900 ° C or higher, preferably at a temperature of 1000 to 1300 ° C.

The 1st table shows the chemical composition of the steel which used this invention and the comparative example.

Steels B to G, J, L, N to T, V to X, and Z are suitable for the composition of the present invention, and steels A, H, I, K, M, U, Y, and a are comparative steel grades.

The second table makes the steel shown in the first table into a steel ingot with a thickness of 110mm after the solvent, and after forming it into a sheet thickness of 15mm by hot rolling by heating at 1200 ° C, after annealing, the direct magnetization characteristics and the ferrite grain size The result of the measurement is integrated. The annealing was carried out under the usual conditions of 1 to 3 hours of heating holding time and about 100 ° C / hr to 500 ° C / hr of cooling rate.

In Table 2, No. 1 ~ 9, No. 21 is Sol. The influence of Al amount is investigated. No. 21 is a comparative example of annealing. FIG. 1 summarizes these results.

No. 10-13, No. 25 shows the effect of the amount of C + N, and FIG. 2 shows No. Summed up by adding the result of 4. According to this, deterioration of B _0.5 value is recognized when C + N amount exceeds 0.007% in Ti addition.

No. In 14-16, the influence of the amount of Mn was investigated, and deterioration tendency of the DC magnetization characteristic is recognized with increase of Mn amount, but if it is a range which does not exceed 0.5 weight%, it is estimated that a favorable characteristic can be ensured.

No. 17 to 20 are the effects of the amount of Si, and as the amount of Si increases, the decrease of the magnetic flux density (B _0.5 cl, B ₁ cl, B ₂₅ value) due to the decrease in saturation magnetization is recognized, but still good characteristics are secured. have. In addition, it is well known that addition of Si increases the specific resistance of steels such as Al. Therefore, when applied to soft magnetic steels used in alternating magnetic fields, it is expected to have an effect of reducing iron loss. Can be.

No. 22-24, No. 26, No. 27 examines the effect of Ti addition, and since Ti is fixed by Ti addition, favorable characteristic is recognized. In particular, No. 23 is No. Example of this invention which added Ti to the steel corresponded to 11 (comparative example), and No. 26 is No. Although Ti is added to the steel corresponded to 25 (comparative example), although both are C + N> 0.007%, the fixation of N enough to Ti is made and No. 11, No. Significant improvement in characteristics is recognized as compared with Comparative Example 25.

In addition, the third table shows the result of having investigated the direct-current magnetization characteristics of some steels in the first table by hot rolling after cold rolling, and in the same manner as in the example of the second table after ordinary annealing. Moreover, the cold rolling reduction amount of the cold rolled material shown by these invention examples and comparative examples is 50 to 80%.

In Table 3, No. 1, No. 2 is a comparative example by steel U. Meanwhile, No. 3-6 is an Example of this invention. These examples of the present invention are No. 1, No. Compared with the comparative example of 2, better DC magnetization characteristics are shown.

In either of the second and third tables, the ferrite grain size of the present invention having good direct magnetization characteristics is 0.5 mm or more.

Table 1

2nd table

3rd table

As described above, the soft magnetic steel according to the present invention has excellent DC magnetization characteristics, and thus can be easily magnetized even in extremely weak magnetic fields, and is extremely useful as a high-performance iron core material or a high-performance magnetic shielding material.

Industrial use

The present invention can be applied to ferromagnetic magnetic steels requiring high DC magnetization characteristics such as electromagnet core material and magnetic shielding material.

The present invention relates to a ferromagnetic magnetic steel material requiring high DC magnetization characteristics such as electromagnet core material, magnetic shielding material.

1 is Sol. A diagram showing the relationship between the amount of Al added and the direct magnetization characteristics (B _0.5 value, B ₂₅ value),

2 is a diagram showing the relationship between the C + N content and the direct current magnetization characteristic (B _0.5 value).

Claims (2)

By weight%, Al: 0.5-2.5%, Si: 1.0% or less, C + N: 0.007% or less, Mn: 0.5% or less, oxygen: 0.005% or less, balance Fe and inevitable impurities, and also ferrite A ferromagnetic magnetic steel material having a grain size of 0.5 mm or more and exhibiting a magnetic flux density value of 11000 G or more at 0.5 Oe, a magnetic flux density value of 15500 G or more at 25 Oe, and a coercive force of 0.4 Oe or less in a state where the lattice strain is sufficiently removed. By weight%, Al: 0.5 to 0.5%, Si: 1.0% or less, C + N: 0.014% or less, Mn: 0.5% or less, Oxygen: 0.005% or less, Ti: 0.005 to 1.0%, balance Fe and unavoidable impurities And a ferrite grain size of 0.5 mm or more and exhibit a magnetic flux density of 11000 G or more at 0.5 Oe, a magnetic flux density of 15500 G or more at 25 Oe, and a coercive force of 0.4 Oe or less in a state where the lattice strain is sufficiently removed. Ferromagnetic magnetic steels.