JPS6128015B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an Fe-Co-Mn-C alloy for magnetic materials. Fe-Cr-Co alloys, which are currently used in various fields, are known as permanent magnets that are easy to cold-work, such as rolling, wire drawing, and swaging. Efforts are being made to further improve the magnetic properties. By the way, in order to obtain properties as a permanent magnet for Fe-Cr-Co alloys, a heat treatment method is used to appropriately disperse a strong magnetic phase and a weak magnetic phase. However, this heat treatment method involves lowering a specific temperature range at a predetermined slow rate (for example, 20°C/hour) and then subjecting it to an aging treatment for a long time, and the heat treatment time is 10 hours or more. This is the method you need. Furthermore, since the rate of temperature reduction greatly affects the magnetic properties, it has been necessary to strictly control the temperature reduction program. In order to solve this problem, instead of continuously decreasing the temperature, we
A method has been proposed in which the temperature is lowered stepwise at intervals of 0.degree. C., but this still requires a long heat treatment. The present invention does not require the strict temperature-lowering program management or long-term heat treatment required for heat treatment as in Fe-Cr-Co alloys, and the desired magnetic properties can be obtained with a short heat treatment of about one hour. Furthermore, the present invention provides an alloy for magnetic materials which has the great feature of being able to make desired locations non-magnetic. The magnetic material alloy of the present invention contains 30 to 55% by weight of Co, 15 to 27% by weight of Mn, and 0.3 to 2.0% by weight of C.
It is an alloy characterized by V being 2.9% by weight or less and the balance being Fe. Fe is 910℃~1390℃
It has a nonmagnetic face-centered cubic structure (hereinafter referred to as γ phase) in the temperature range of Fe
When adding Mn to and increasing the amount of Mn added, γ/
(γ+α) boundary moves toward the low temperature side, and
Addition of a small amount of C results in a high temperature non-magnetic γ phase at room temperature. When the Fe Mn C alloy described above is cold worked to a high strength and heat treated at low temperature to transform the γ phase into a ferromagnetic phase, a high coercive force (hereinafter referred to as Hc) cannot be obtained with a small amount of Mn. When the amount of Mn increases, the amount of magnetization decreases. Furthermore, the addition of Co has the effect of increasing the amount of magnetization of the ferromagnetic phase. Further, V is an element that forms a γ region with respect to Fe at high temperatures and solidifies, thereby improving the magnetic properties of the alloy of the present invention. The above-mentioned alloy of the present invention is heat treated in a temperature range in which a non-magnetic γ phase is obtained in a thermal equilibrium state, and then rapidly cooled to room temperature to maintain a γ phase state without phase transformation. It was also found that the alloy does not crack even when subjected to intense cold wire drawing, maintains a non-magnetic state, and has good workability. A major feature of the alloy of the present invention is that, after these cold workings, desired magnetic properties can be obtained by simple heat treatment in a much shorter time than with conventional alloys. Next, the details of the present invention will be explained by referring to examples. First, as samples, Nos. 1 to 12 shown in Table 1 were used.
Twelve compositions were selected. For comparison, a known Fe-Cr-Co-Ti alloy was selected as No. 13.

[Table] First, alloy ingots having the chemical composition shown in Nos. 1 to 6 in Table 1 were heated at a temperature of 1100℃ for 1 hour.
After solution treatment in an Ar atmosphere, it was quenched by immersing it in a 10% NaOH aqueous solution. Cutting out small pieces from each of these alloy ingots and measuring the amount of magnetization,
The saturation magnetic flux density (hereinafter referred to as Bs) is
It was about 10 Gauss. Furthermore, when the crystal structure was examined by X-ray diffraction, no diffraction pattern other than a face-centered cubic structure was observed, confirming that the γ phase was obtained at room temperature. Nos. 7 to 12 are alloy ingots with chemical compositions that are outside the scope of the claims of the present invention, but when subjected to the same treatment as alloy ingots Nos. 1 to 6, Nos. 7 to 10 were found to be No. .1～
Similar results as in Example 6 were obtained. But No.11 and
No. 12 alloy ingots each have Bs=
14.5 KGauss, Bs = 13.8 KGauss, and the non-magnetic γ phase could not be introduced at room temperature with the chemical compositions of No. 11 and No. 12. After removing the surface oxide film of the alloy ingots No. 1 to 10 in the γ phase state, they were subjected to cold wire drawing, cold swaging, or cold rolling, and then heat treated in an Ar atmosphere. No. 13 in Table 1 is an example of an Fe-Cr-Co alloy. Alloy ingot No. 13 was subjected to solution treatment at 1180°C for 1 hour in a hydrogen atmosphere, and then quenched by immersion in water. Thereafter, it was subjected to cold wire drawing with an area reduction rate of 70%, heat treated again at 650°C for 1 hour in a hydrogen atmosphere, and rapidly cooled in water (condition A). After that, heat treatment was performed again (in a hydrogen atmosphere) from 625℃ to 505℃ while decreasing the temperature at a rate of 18℃/hour.
Heat treatment was performed at 505° C. for 8 hours in a hydrogen atmosphere (condition B). Table 2 shows the relationship between the composition of the samples shown in Table 1, various processing conditions, and magnetic properties.

[Table] Samples Nos. 1 to 6 in Table 2 have compositions within the claimed range of the present invention, can be heat treated in a short time, and exhibit good magnetic properties. On the other hand, Nos. 7 to 10 have compositions outside the claimed range, and their magnetic properties are significantly inferior to those within the claimed range. Also known as Fe-Cr
-Co-based alloys can only obtain considerably inferior magnetic properties when subjected to the same 60-minute heat treatment as the alloys of the present invention, and in order to obtain magnetic properties equivalent to those of the alloys of the present invention, conditions A and B described above must be met. This requires a long processing time. Note that the alloy of the present invention is not limited to the heat treatment conditions shown in Table 2, and the temperature is 520°C to 400°C.
Good magnetic properties can be obtained by selecting appropriate heat treatment conditions in the range of 180 minutes to 3 minutes. Based on the results in Table 2, the claimed composition range of the alloy of the present invention is limited as follows. If Co is outside of 30% to 55% by weight, the coercive force and residual magnetic flux density (hereinafter Br
), Br/Bs, and maximum energy product (hereinafter referred to as BHmax) deteriorated. Therefore, Co is
A range of 30% to 55% by weight is required. but
When Co is 30% by weight, adding more than 27% by weight of Mn will reduce the amount of magnetization, making it impractical.
At 55% by weight, no magnetically hard alloy could be obtained if Mn was added below 15% by weight to the alloy. Therefore, the range of Mn was set to 15% to 27% by weight. For the alloy of the present invention containing 27% by weight of Mn, it was impossible to introduce the γ phase at room temperature when C was added below 0.3% by weight. Further, up to 2.0% by weight of C could be dissolved in the γ phase of the alloy of the present invention. Mn
The alloy of the present invention containing 27% by weight and 0.3% by weight of C could be subjected to strong cold working. Therefore, the range of C was set to 0.3% to 2.0% by weight. V
When added in excess of 2.9% by weight, it was possible to introduce the γ phase at room temperature. As shown in Table 2 above, alloys having compositions within the scope of the claims of the present invention are complex like Fe-Cr-Co alloys and do not require long heat treatment, but can be easily heat treated. It was found that it has good magnetic properties. Furthermore, in the alloy of the present invention, the alloy ingot is subjected to cold wire drawing with an area reduction rate of 99%, and the resulting alloy wire is placed in a through-hole furnace in a hydrogen atmosphere with a soaking length of 200 mm and maintained at a temperature of 480°C. For example, in composition No. 1 shown in Table 1, even if a heat treatment method is used in which the material is fed continuously from one end at a speed of 60 mm/min, taken out from the other end continuously, and wound onto a drum with a diameter of 400 mm, Hc=570 (Oe), Br=9.4 (KGauss), Sq=
Good magnetic properties of 0.97 and BHmax=3.2 (MGauss・Oe) were obtained. Furthermore, another major feature of the alloy of the present invention is that after heat treatment to obtain the desired magnetic properties, a desired location in the obtained alloy is heated at about 1000°C for about 1 second and then rapidly cooled. The place becomes non-magnetic. This will be explained using an example. Table 1
The composition of No. 1 was cold swaged at 440℃.
-The rod-shaped alloy obtained by heat treatment for 60 minutes was rotated at a speed of 1 revolution/second around the central axis in the longitudinal direction, and irradiated with a laser beam of 1 mm diameter from a 5W continuous wave YAG laser for 10 seconds. . When we cut out the part irradiated with this laser and measured the amount of magnetization, we found that the Bs value was approximately 10 Gauss, confirming that it was almost in the nonmagnetic γ phase. Therefore, the alloy of the present invention can be made nonmagnetic at a desired location using a laser beam, an electron beam, an infrared beam, etc., and it is possible to combine a ferromagnetic region and a nonmagnetic region. As described above, the alloy of the present invention has the characteristics that it can be easily cold-worked for strength and that it can be heat-treated very easily.Additionally, the alloy of the present invention can be made non-magnetic in desired parts, making it useful in many industrial fields. It is a magnetic material.

Claims (1)

[Claims] 1 Co: 30-55% by weight, Mn: 15-27% by weight,
C: 0.3 to 2.0% by weight, V: 2.9% by weight or less, balance Fe
Fe-Co- for magnetic materials characterized by consisting of
Mn C alloy.