JPS6128023B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a Fe-Co-Mn-C magnetic alloy. Fe-Co-Mn-C-B alloy is a magnetic material alloy that can be subjected to strong cold working, has good magnetic properties with simple heat treatment, and can be made non-magnetic at desired locations. As, already,
It has been proposed by the inventors of the present invention. Although Fe-Co-Mn-C-B alloy has the above-mentioned excellent properties, it is slightly inferior in corrosion resistance compared to other alloys for magnetic materials, such as e-Cr-Co alloys. There is. The present invention provides an alloy for magnetic materials that has excellent corrosion resistance without impairing the above-mentioned excellent properties of the Fe-Co-Mn-C-B alloy. The alloy for magnetic materials of the present invention contains 30 to 55% by weight of Co, 15 to 20% by weight of Mn, and 0.3 to 1.8% by weight of C.
It is an alloy characterized by B being 0.022% by weight or less, Cr being 2 to 15% by weight, and the balance being Fe. Fe has a non-magnetic face-centered cubic structure (hereinafter referred to as γ phase) in the temperature range of 910℃ to 1390℃, but when rapidly cooled to room temperature, it changes to a magnetic body-centered cubic structure (hereinafter referred to as α phase). . Adding Mn to Fe,
When the amount of Mn added is increased, the γ/(γ+α) boundary shifts toward the lower temperature side, and when a small amount of C is added, a high-temperature nonmagnetic γ phase is obtained at room temperature.
Furthermore, the addition of Co has the effect of increasing the amount of magnetization of the alloy of the present invention and increasing the coercive force. B is Fe
At high temperatures, a γ region is formed and solid solution is formed, and Fe−Co−
It is an element that improves the magnetic properties of Mn-C alloys.
Further, the addition of Cr is a major feature of the alloy of the present invention, and is an element necessary for the alloy of the present invention to have corrosion resistance. 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 is an alloy that does not crack even when subjected to intense cold wire drawing, maintains a non-magnetic state, and has good workability. Furthermore, after performing these cold workings, it was found that the alloy of the present invention, which had the desired magnetic properties through heat treatment, had corrosion resistance equivalent to that of Fe-Cr-Co alloys. Next, the alloy of the present invention will be explained using examples. First, as a sample, No.1~ shown in Table 1 below.
Seven types of compositions up to 7 were selected. Also for comparison
Fe-Co-Mn-C- known as No.8 and No.9
B alloy and Fe-Cr-Co-Ti alloy were selected.

[Table] First, alloy ingots having the chemical composition shown in Nos. 1 to 4 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. In addition, when the crystal structure was examined by X-ray diffraction, no diffraction pattern other than an in-plane cubic structure was observed, confirming that the γ phase was obtained at room temperature. Nos. 5 to 6 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 the alloy ingots of Nos. 1 to 4, No. 5 had similar results. was gotten. However, No. 6 alloy ingot is
Bs=1.1 KGauss, and the nonmagnetic γ phase could not be introduced at room temperature. Nos. 7 to 8 are alloy ingots with the conventional chemical composition of Fe-Co-Mn-C-B without the addition of Cr, and when subjected to the same treatment as the alloy ingots Nos. 1 to 4, the same results were obtained. The results were obtained. After removing the surface oxide film of the alloy ingots in the γ phase state of Nos. 1 to 5 and Nos. 7 to 8, they were subjected to cold wire drawing with an area reduction rate of 97%, and then heat treated in an Ar atmosphere. provided. Also, No.9 in Table 1 is
This is an example of a Fe-Cr-Co alloy. Alloy ingot No. 9 was solution-treated at 1180°C for 1 hour in a hydrogen atmosphere, and then quenched by immersion in water. after that,
Cold wire drawing process with area reduction rate of 70% is applied, and then heated to 650℃ again.
The sample was heat-treated in a hydrogen atmosphere for 1 hour and quenched in water (condition A). Then again from 625℃ to 505℃
Heat treatment was performed in a hydrogen atmosphere at a rate of 18°C/hour to 505°C for 8 hours (condition B). Next, Table 2 shows the relationship between the composition of the samples shown in Table 1, various processing conditions, and magnetic properties.

【table】

These are the conditions in [Table].
From the magnetic properties in Table 2, conventional Fe-Co-Mn
It has been found that adding Cr to the -C-B alloy does not deteriorate magnetic properties such as coercive force (Hc), residual magnetic flux density (Br), Br/Bs, and maximum energy product (BHmax). Next, the samples having the magnetic properties shown in Table 2 were subjected to a corrosion resistance test at a temperature of 50° C. and a humidity of 90%, and the results are shown in Table 3. Evaluation was performed visually to determine the presence or absence of rust.

[Table] Shown.
The samples in Table 3 with 2% or more of Cr added are
It can be seen that the sample has corrosion resistance equivalent to that of the Fe-Cr-Co-based sample. Based on the results shown in Tables 2 and 3, the claimed composition range of the alloy of the present invention is limited as follows. Cr is 2
If the amount is less than 1% by weight, the effect of Cr on corrosion resistance cannot be obtained, and if Cr is added in excess of 15%, it becomes impossible to introduce the non-magnetic γ phase at room temperature. Therefore, Cr must be in the range 2-15% by weight. When the Co content was less than 30 to 55% by weight, the coercive force, residual magnetic flux density Br/Bs, and maximum energy product deteriorated. Also, when Co is 30% by weight, Mn
When more than 27% by weight is added, the magnetization decreases, making it impractical, and when Co is 55% by weight, adding less than 15% by weight of Mn does not result in a magnetically hard alloy. For the alloy of the present invention containing 27% by weight of Mn, it was impossible to introduce the γ phase at room temperature if less than 0.3% by weight of C was added. Furthermore, up to 1.8% by weight of C could be dissolved in the γ phase of the alloy of the present invention. B is 0.022% by weight
It was possible to introduce the γ phase at room temperature by adding more than Therefore, Co is 30 to 55% by weight, Mn is 15 to 27% by weight, C is 0.3 to 1.8% by weight,
Cr was limited to 2 to 15% by weight, and B was limited to 0.022% by weight. As described above, the alloy of the present invention can be easily cold-worked for strength, has good magnetic properties with simple heat treatment, can be made non-magnetic in desired parts, and has excellent corrosion resistance. It is a useful magnetic material in many fields.

Claims (1)

[Claims] 1 Co: 30-55% by weight, Mn: 15-27% by weight,
C: 0.3 to 1.8% by weight, B: 0.022% by weight or less,
An Fe-Co-Mn-C based magnetic alloy for magnetic materials, characterized by comprising Cr: 2 to 15% by weight, and the balance being Fe.