JPH03153823A - Production of sheet-like directional fe-cr-co permanent magnet - Google Patents

Abstract

PURPOSE:To produce a sheet-like directional permanent magnet having high energy product by subjecting an Fe-Cr-Co alloy steel plate to respectively speci fied heating treatment and cold rolling, applying specific magnetic annealing to the resulting sheet, and then carrying out aging annealing at a temp. lower than the magnetic annealing temp. CONSTITUTION:A steel plate to be a base material for an Fe-Cr-Co permanent magnet alloy is subjected to heating treatment at 700-1300 deg.C and then to cold rolling at >=70% rolling reduction. Subsequently, while applying a magnetic field of >=1000e in which the direction of magnetic field conforms with the direction of 45 deg.+ or -15 deg. with respect to the cold rolling direction of this steel sheet, annealing is performed at 600-700 deg.C. Successively, aging annealing is applied to this steel sheet at a temp. lower than the above magnetic annealing temp. By this method, the sheet-like directional Fe-Cr-Co permanent magnet having magnetic properties of >= about 5MGOe (BH)max even in the case of <= about 1mm sheet thickness can be mass-producibly.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a method for manufacturing Fe-Cr-Co permanent magnets, particularly for electronic magnets that require unidirectionality in thin plates. This invention relates to a method of manufacturing a permanent magnet suitable for use as a permanent magnet material for instrumental parts.

<Prior art> Fe-Cr-Co magnets are magnets that have achieved high coercive force (Hc) by utilizing spinodal decomposition, and the energy product ((Bll)
saw) is on the same level as 5-IOM Gos and alnico magnets, and has characteristics such as easier cold working than alnico magnets.

Regarding this Fe-Cr-Co magnet, special public Sho-2
No. 0251, Special Publication No. 51-18884 and Special Publication No. 18884
-29859 As disclosed in each publication, its characteristics are (Bll) saw4~5 M GOe, Hc 4
0G to 5000s has been obtained.

Moreover, ^pp1. Phys, Lett,, 37
(1980) p. 92-93, J. Appl, P.
hys, 54 (1983) p. 5400-540
As reported in 3, (Bit)m can be
Excellent properties of axlO~11MGOe have also been obtained.

However, improvements in permanent magnet properties have been remarkable, and recently, in research on rare earth W4 magnets, for example, JP-A-59-460
As disclosed in Publication No. 08, REM-Fe-B
Magnets with (all)@ax as high as 25 MGOe are now manufactured.

On the other hand, in recent years, with the development of the electronic equipment industry, there has been a strong desire to improve the properties of permanent magnets, and various demands have been made regarding practical shapes.

Among these requests, in order to meet the request for a thin plate shape,
Plastic rai1 stone and sea) H1 stone were devised.

These magnets are made by dispersing ferrite or rare earth magnet powder in a plastic or rubber plate. For this reason, the permanent magnetic property (811) steel ax is ~2MGOe, REM -Fe when ferrite powder is used.
- When B-based powder is used, it is 7 to 10 MGOe, which is lower than that of bulk sintered material. Additionally, there is a limit to the thickness of the magnet, which is at most 1.0 to 2. A thickness of approximately 0.0 m is the usable thickness.

If the thickness is made any thinner, it will be extremely difficult to manufacture a plate-shaped magnet that satisfies the characteristics and shape. In particular, the rare earth i
When ff stone powder is used, it is easy to obtain and has a low IJ-4 degree, so the permanent magnet characteristics are sensitive to changes in the surrounding environment, and it is difficult to operate in order to construct electronic parts that require precision. There was a problem with stability, and for this reason, the applications had to be limited.

In this regard, the Fe--Cr--Co based magnet mentioned above is a Cr-containing alloy and has high rust prevention properties (and since it is also an Fe--Co based magnet, it has a high Curie temperature and extremely good temperature characteristics.

However, although it is possible to use the above-mentioned columnar crystals or single crystal materials in hopes of improving properties in a laboratory setting, it is hardly practical when considering mass production on an industrial scale.

<Problems to be Solved by the Invention> From the background described above, the purpose of the present invention is to
- To propose a permanent magnet V-wiring method that makes it possible to obtain a large amount of Co-based alloy magnets having a ([111) wax of 5 MGOe or more on an industrial scale even if the plate thickness is 111 or less. .

Means for Solving the Problem> The present invention provides the above-mentioned solutions. ! $! In solving m, the following methods were basically used.

In other words, by taking advantage of the good workability of Fe Cr Co alloys and applying high pressure to a predetermined thickness, the material is given directionality, and then a magnetic field direction parallel to that direction is applied. The permanent magnet properties are improved by performing annealing while applying a magnetic field to cause spinodal decomposition, and then performing an aging treatment.

That is, the present invention provides '1jiFi Fe-Cr-C
When manufacturing an o-based permanent magnet alloy, a steel plate serving as the base material is subjected to heat treatment in a temperature range of 700 to 1300'C, then cold rolled at a reduction rate of 70% or more, and then this steel plate is While applying a magnetic field of 1000e or more with the magnetic field direction aligned in the direction of 45° ± 15" with respect to the cold rolling direction,
This is a method for manufacturing a thin plate-like oriented Fe-Cr-Co permanent magnet, which is characterized by performing annealing in a temperature range of 0 to 700°C, and then performing aging annealing at a temperature lower than the magnetic field annealing temperature.

<Function> The base steel plate used in the present invention may be formed by blooming an ingot into a slab, or by continuous casting to directly form a slab, and then hot rolling to form a hot-rolled plate. Prior to cold rolling, heat treatment such as normalizing or solution treatment is required for the above base steel sheets in order to erase the residual ff history during hot rolling. It is also economical, and if the temperature exceeds 1300'C, the surface of the steel plate may melt depending on the components, so the heating temperature is set in the range of 700 to 1300°C.

Next, when the cold rolling reduction ratio is less than 70%, the orientation becomes sharp (not only the 1001 <110> orientation cannot be obtained, but also other crystal orientations are mixed, so the cold rolling reduction ratio is set to 70% or more.

Further, in the cold rolling of the base material steel plate, cold rolling including intermediate annealing may be performed twice, but the final rolling reduction ratio needs to be 70% or more.

Figure 1 shows Fe-26%Cr-15,5%Go-3,5
An alloy material having a composition of %Mo was made into a steel ingot, then hot blooming rolled to make a slab, further heated and hot rolled to make a hot rolled sheet, and then annealed at 920''C for 2 minutes. 70 showing the change in texture when the cold reduction rate is changed after
% or more, a sharp (1001<110> structure) is obtained.

Next, for the above-mentioned cold rolling with a reduction rate of 65.70 and 90%, the direction of the magnetic field was changed and 100% was rolled at a temperature of 680°C.
Annealed in a magnetic field of 00e and then further annealed to 660~400'C5
Regarding the change in magnetic properties when cooling for 0 hours, as shown in Figure 2, the angle between the rolling direction and the magnetic field direction is 30~
5MGOe in a range of 60” or 45±15°
The above has been obtained. At this time, if the reduction rate is less than 70%, 5 MGOe or more cannot be obtained.

If the temperature range for annealing in a magnetic field is less than 600°C, two-phase separation due to spinodal decomposition takes time and becomes uneconomical.
On the other hand, if the temperature exceeds 700°C, spinodal decomposition becomes difficult and magnetic properties deteriorate, so zero-age annealing, which needs to be in the range of 600 to 700°C, promotes grain growth of spinodal decomposition particles obtained by magnetic field annealing. However, if the temperature is higher than the annealing temperature in a magnetic field, the orientation of the particles, which are regulated in the direction of the magnetic field by the applied magnetic field, will be disrupted, so the temperature is set lower than the annealing temperature in the magnetic field. In addition, even if age annealing is performed to a temperature lower than 400"C, the magnetic properties will not improve much and it is rather uneconomical, so the lower limit of the age annealing temperature is preferably 400 °C. Therefore, the age annealing temperature range is , below the annealing temperature in a magnetic field to 400°C.

In the second temperature range, cooling may be performed by changing the cooling rate, or isothermal annealing may be performed at an arbitrary temperature.

Furthermore, even if a magnetic field is applied during this annealing, the characteristics do not change significantly.

FIG. 3 shows the influence of the annealing temperature in a magnetic field on the magnetic properties of the materials used in FIG. 2 when a magnetic field is applied in a direction of 45 degrees with respect to the rolling direction.

5MGOe or more can be obtained in the range of 600 to 700°C.

In addition, the aging annealing at this time is 20°C higher than the magnetic field annealing temperature.
Cooling was carried out over a period of 50 hours from low temperature to 4QO''C.

The strength of the applied magnetic field needs to be 1000e or more. For the sample used in Figure 3, the change in magnetic properties when varying the strength of the Kl field is applied is shown in Figure 4. As can be seen from the 0 diagram in Figure 4, (Bll) a+ax increases rapidly up to 1000e, but At 1000e or more, although it gradually increases, no significant improvement is observed.Therefore, it is sufficient that the magnetic field strength is 10000e or more.

Next, the components of this alloy system will be explained.

Co improves the saturation magnetic flux density of this alloy system, and (Bl
l) At the same time as improving wax, it increases the Chierly temperature in this alloy system, and effectively contributes to increasing the effect of spinodal decomposition during magnetic field annealing to further improve magnetic properties. Content is 3wt% (hereinafter simply expressed as %)
If it is less than 35%, not only will spinodal decomposition take time, but a sufficient magnetic field improvement effect will not be obtained.
If the Co content exceeds 3 to 3, the T phase and ordered phases of Fe and Co will partially precipitate, resulting in uneven spinodal decomposition, resulting in deterioration of properties and an additional disadvantage of increased cost. It is desirable to set it to about 35%.

C is an element that alloys with Fe to form an α phase, and by forming a Pe-Cr alloy in a supersaturated solid solution state,
The subsequent age annealing effectively causes spinodal decomposition. However, if the content is less than 10%, it is difficult to induce spinodal decomposition even if the content is less than 10%.
If the Cr content exceeds 10% to 35%, the formation of α phase is likely to be promoted, resulting in brittleness and deterioration of workability, as well as a decrease in the saturation magnetization of the alloy, resulting in a decrease in (Bit) wax. It is desirable that the

In addition, as subcomponents, Ti, Zr, V, Nb, T
The total of elements such as a, Mo, WSB, Ai Sis Ge5Sn, alone or in combination is 0. O1~5.0s
These elements may be added in a range of et%. These elements are α phase forming elements, and if the amount is less than 0.01%, they are not useful for producing an α phase single solid solution prior to spinodal decomposition.
If it exceeds %, the saturation magnetic flux density will be lowered, α phase will be formed, and workability will be deteriorated, and at the same time spinodal decomposition will become non-uniform, so the above range is preferable.

In the present invention, an alloy having the above-mentioned composition is melted in a converter or electric furnace, the ingot is decomposed and rolled into a slab, or directly cast into a slab by continuous casting, and then hot-rolled to form a hot-rolled sheet. This can be used as a base material steel plate. By cold rolling these steel plates to a thickness of IH or less and subjecting them to the above-mentioned treatment, a thin plate orientation F that satisfies 5MGOe is obtained.
ecr-C.

It is possible to easily mass-produce permanent magnets on an industrial scale.

The following will be specifically explained based on examples.

<Example> Example I A 30 kg ingot having the components shown in Table 1 was prepared, and after grinding the surface of the ingot by about 1 inch, it was heated at 1260°C for 3
4. Heating for 0 minutes and immediately hot rolling. It was made into a hot rolled sheet with OI thickness. After removing scale on the surface of this sample with acid, heat treatment was performed for 2 minutes at various annealing temperatures shown in Table 1. This plate was cold rolled at a reduction rate of 87.5% to a thickness of 0.5 mm. After that, an IKOe magnetic field was applied in the 45° direction from the rolling direction, and annealing was performed at 670°C for 40 minutes, and the temperature was increased to 50°C from 650 to 400°C.
Cooled down over time. 30X30m for these boards
Samples cut to the size of B-Hlill were stacked to have a thickness of 5 or more when stacked, and a measurement magnetic field of up to 10 KOe was applied using an automatic B-H) racer.
The line was measured and (Bll) IIas was examined. The magnetic properties obtained at that time are also listed in Table 1.

Underwater Example 2 not applicable to the present invention Fe-28Cr-14,6Go -2,7Mo -0,
A 3.0 m thick hot rolled plate was produced from a 50 kg ingot having a composition of 3W, and after annealing at 1000'C for 2 minutes, a cold rolled plate was produced at the rolling reduction ratio shown in Table 2.

This pre-rolled material was annealed for 30 minutes while varying the applied magnetic field strength in the 45° direction, and then cooled to 650-500''C over 50 hours.The magnetic properties measured by the method shown in Example 1 The results are also listed in Table 2.

*Example 3 not applicable to the present invention A hot-rolled sheet with a thickness of 2.0 mm was prepared from a 30 kg ingot having a composition of Fe-25Cr-15Co-3,25i, annealed at 950°C for 5 minutes, and then rolled. It was cold rolled at a rate of 95% and finished to a thickness of 0.1 mm. This plate was annealed at 680"C for 30 minutes by changing the direction of the IKOe magnetic field applied to the rolling direction, and then
5 hours at 0゛C, 0 hours at 550℃, 15 hours at 500℃
Example of stepwise annealing of time! The magnetic properties were investigated using the method shown below. The results are shown in Table 3.

<Effects of the Invention> Thus, according to the present invention, by using the Fe-Cr-Co alloy, unidirectional 5MGOe or more (Bl
l) It is possible to industrially produce a permanent magnet having a thickness of 1 inch or less and having a+ax. Moreover, up to the final magnetic field annealing process,
It can be handled in coiled form and is suitable for mass production on an industrial scale.

[Brief explanation of the drawing]

Figure 1 is a graph showing the effect of cold rolling reduction on the scratch diagram, Figure 2 is a graph showing the effect of the angle between the cold rolling direction and the applied magnetic field on (all) wax, and Figure 3 is ( BH)I
Graph showing the influence of magnetic field annealing temperature on Iax, 4th
The figure is a graph showing the influence of applied magnetic field strength on (Bll)wax.

Claims (1)

[Claims] When manufacturing a thin plate-shaped Fe-Cr-Co permanent magnet alloy, the base material steel plate is heat treated in a temperature range of 700 to 1300°C, and then cold rolled at a reduction rate of 70% or more. Then, annealing is performed in a temperature range of 600 to 700 °C while applying a magnetic field of 1000 e or more with the magnetic field direction aligned at 45 ° ± 15 ° with respect to the cold rolling direction of the steel plate, and then annealing is performed in a temperature range of 600 to 700 ° C. Thin plate-shaped oriented Fe-Cr characterized by aging annealing at a temperature lower than the annealing temperature
- A method for producing a Co-based permanent magnet.