JP3521998B2 - Soft magnetic stainless steel for relay iron core - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic stainless steel for a relay iron core.

[0002]

2. Description of the Related Art Conventionally, a relay iron core has been most commonly made of electromagnetic soft iron. However, since electromagnetic soft iron is inferior in corrosion resistance, iron core parts were plated after processing to provide corrosion resistance. Ni plating, unichrome plating, etc. are generally used for this plating.

[0003]

Electromagnetic soft iron, which has been most widely used for relay iron cores, is not only expensive to be plated when it is plated for corrosion resistance, but also deteriorates in magnetic characteristics. The problem of being inevitable was attached. In general, it is unavoidable that the plating thickness varies in plated products, but even a slight variation in the plating thickness causes a problem that in the case of a relay iron core, the attraction force required when applying the magnetic field varies.

Therefore, an object of the present invention is to provide an iron core material which is excellent in corrosion resistance as a raw material and which has relay characteristics comparable to conventional electromagnetic soft iron properties, which makes the relay excellent in corrosion resistance and good. It is to provide a relay iron core with characteristics.

[0005]

According to the present invention, in% by weight,
C: 0.02% or less, Si: 0.3 to 2.0%, Mn: 0.0.
7% or less, P: 0.04% or less, S: 0.005% or less,
Ni: 0.3% or less, Cr: 9.0 to 14.0%, N: 0.0.
02% or less, O: 0.010% or less, Al: 2.0% or less, depending on the case, Ti: 5 (C + N)
The content of each component is adjusted so that the F value or F'value (when Ti is included) defined by the following formula is 0 to 4%, and the balance is Fe and unavoidable. Provided is a soft magnetic stainless steel for a relay iron core, which is made of static impurities. F value = Cr + Si + 2.1 (Ti + Al) -37.0 (C
+ N) -2.0Ni-0.6Mn-10.8

Therefore, according to the present invention, there is also provided a relay iron core made of soft magnetic stainless steel having the above composition.

[0007]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies on the effect of alloying elements and microstructure on the magnetic properties required for relay iron cores based on ferritic stainless steel. It has been found that, in a certain composition system of a series of stainless steels, it exhibits properties that can be sufficiently used as a relay iron core material in a narrow composition range.

The action of each component in the steel of the material of the present invention and the reason for limiting the content range will be outlined below.

When C acts to form carbides in steel, it deteriorates magnetic properties and corrosion resistance.
The lower the iron core of the relay, the better.
It is 2% by weight or less.

Si is a ferrite-forming element and effectively acts to improve magnetic properties. For this purpose, it is necessary to contain 0.3% by weight or more. But 2.
On the other hand, if it exceeds 0% by weight, the magnetic flux density will be lowered and the workability of the steel will be deteriorated. Therefore, the Si content is limited to 0.3 to 2.0% by weight.

Mn is an element necessary for deoxidation during steel making, but is also an element that deteriorates the magnetic properties. Therefore, the upper limit is set to 0.7% by weight.

Since P is an element that deteriorates the magnetic properties of steel, its content should be small. Therefore, the upper limit was made 0.04% by weight.

S is an impurity element, and its upper limit is set to 0.005% by weight in order to suppress the formation of sulfide that deteriorates corrosion resistance and magnetic properties as low as possible.

Ni is an austenite-forming element, and if its content increases, it deteriorates the magnetic properties, so the content is made 0.3% by weight or less.

In order to obtain a relay iron core having good corrosion resistance, Cr must be contained in an amount of 9.0% by weight or more. However,
Since the magnetic flux density decreases when a large amount of Cr is contained, the upper limit is set to 14.0% by weight.

N forms a nitride of Al or Ti and deteriorates the magnetic properties, so the upper limit was made 0.02% by weight.

If O is mixed as an impurity to form an oxide, it deteriorates the magnetic characteristics, so it must be kept low.
Therefore, the upper limit is set to 0.010% by weight.

Al is added as a deoxidizing material during the melting of steel, and acts to improve the magnetic characteristics by reducing impurities accompanying deoxidation. However, since Al itself is an element that deteriorates the magnetic properties, its upper limit is set to 2.0% by weight.

Ti forms carbon / nitride with C and N, and thereby acts effectively to secure a ferrite single-phase structure. For this purpose, it is necessary to add 5 times or more of C + N. However, since Ti itself acts to deteriorate the magnetic characteristics, the range of Ti is 5 (C + N) to 0.
40% by weight.

In addition to the above regulation of the component composition, by adjusting the amount of each component so that the F value defined by the above formula is in the range of 0 to 4, the magnetic characteristics required for the relay iron core are stabilized. I found that it can be secured.

FIG. 1 shows the F value and the maximum magnetic flux density (G) of a number of test materials (magnetic annealed materials) in which the F value defined by the above equation is changed by changing the amount of each component. It shows the result of examining the relationship.

As shown in FIG. 1, when the F value becomes lower than 0 at the boundary, the maximum magnetic flux density drops sharply,
It is no longer suitable for relay iron core applications. On the other hand, when the F value exceeds 0, the maximum magnetic flux density gradually decreases.
When the value is 4 or less, the maximum magnetic flux density comparable to that of electromagnetic soft iron, for example, approximately 12000 (G) can be secured. Therefore, for relay iron cores, it is necessary to adjust the amount of each component so that the F value is 0 or more and 4 or less, and by this adjustment, in the component system of ferrite stainless steel with good corrosion resistance, the relay iron There is a range that can be a core material. This is because the structure of ferritic stainless steel is involved, and it can be considered that the structure has good magnetic properties when the F value is in this range.

The relationship between the F value and the magnetic characteristics will be concretely shown in the following examples.

[0024]

EXAMPLES Alloy steels having the chemical composition values (% by weight) shown in Table 1 were melted, hot-rolled, cold-rolled and finish-annealed to produce a plate having a thickness of 1.2 mm. Al is conventional electromagnetic soft iron, B1 to 15 are steels of the present invention, and C1 to 4 are comparative steels.

Each steel plate having a thickness of 1.2 mm has an outer diameter of 45 mm,
A ring-shaped test piece with an inner diameter of 33 mm is cut out and 850 ℃ ×
After annealing for 1 hour, AC magnetic measurement was performed at a frequency of 60 Hz to measure the maximum magnetic flux density (G) in a magnetic field of 10 Oersted. In addition, as for Al, the samples which were plated with Ni having different film thickness after annealing were also tested. The measurement results are shown in Table 2.

Further, each of the steel plates was processed into 10 L-shaped relay iron cores, each of which was annealed at 850 ° C. for 1 hour, and the adsorption force of the relay iron cores was evaluated. With respect to Al, after the components were annealed, Ni platings with different film thicknesses were also tested. Figure 2 shows the evaluation of the attraction force of the relay iron core.
The relay iron core 1 is connected to the solenoid coil 2 as illustrated in FIG.
The coil 2 was attached to the coil 2, a voltage of 24 V and a frequency of 60 Hz were applied to the coil 2, and a magnetic field was applied. Then, the average value and standard deviation were obtained respectively.
The results are also shown in Table 2.

Further, each steel sheet was subjected to a salt spray test for 24 hours according to JIS Z2371 to examine the corrosion resistance.
Corrosion resistance was evaluated by visual inspection, which showed almost no rust (○), light rust distribution (△),
It was evaluated in three grades of those in which rust was generated in an area ratio of 10% or more (marked with X). The results are also shown in Table 2.

[0028]

[Table 1]

[0029]

[Table 2]

As can be seen from the results shown in Table 2, the magnetic characteristics of Al electromagnetic soft iron are excellent in the maximum magnetic flux density B = 14600 G without plating, and the attraction force of the relay iron core is also 22.
It shows a high value of 8.8 gf. However, the corrosion resistance is poor in the solid state without plating. On the other hand, for the A1 plated material, the corrosion resistance is good when the plating film thickness is 2.0 μm, but the maximum magnetic flux density decreases as the plating film thickness increases, and the attraction force of the relay iron core also decreases. 6.
At 0 μm, the suction force is 179.2 gf, which does not show the suction force required for the relay iron core. Moreover, all of the plated materials have large variations in the adsorption force (standard deviation σ) and do not exhibit stable relay characteristics.

Further, the comparative steels C1 and C3 having an F value of less than 0 have extremely low maximum magnetic flux densities and low adsorption powers, and therefore are not suitable for relay iron core applications. Also, these have a Cr content of 8.0.
Since it is as low as 4% by weight and 8.13% by weight, the corrosion resistance is also poor.

C2 and C4 with F values of 4.33 and 4.84
Has good corrosion resistance, but since the F value exceeds 4, the maximum magnetic flux density is poor and the attraction force of the relay iron core is also low.

On the other hand, each of the B1 to 15 steels in which the amount of each component is in the range of the present invention and the F value is in the range of 0 to 4 exhibits an excellent maximum magnetic flux density and also has an attraction force for the relay iron core. It shows an excellent value of 200 gf or more. Moreover, the variation of the adsorption force (standard deviation σ) is small and stable relay characteristics are shown. In addition, it has good corrosion resistance. Therefore, it has excellent properties for relay iron cores.

[0034]

As described above, according to the present invention,
Provided is a useful relay iron core material having both corrosion resistance and relay characteristics. It is also highly practical in terms of economy.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an F value and a magnetic flux density B10.

FIG. 2 is a schematic cross-sectional view for explaining a method of evaluating the attraction force of a relay iron core.

[Explanation of symbols]

1 relay iron core 2 solenoid coil

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-70718 (JP, A) JP-A-63-45350 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 38/00-38/60

Claims (2)

(57) [Claims] 1. By weight%, C: 0.02% or less, Si:
0.3-2.0%, Mn: 0.7% or less, P: 0.04% or less, S: 0.005% or less, Ni: 0.3% or less, Cr:
9.0-14.0%, N: 0.02% or less, O: 0.010
% Or less, Al: 2.0% or less, and the amount of each component is adjusted so that the F value defined by the following formula is 0 or more and 4 or less, F value = Cr + Si + 2.1Al-37.0 ( C + N)-
2.0Ni-0.6Mn-10.8 Soft magnetic stainless steel for relay iron cores with the balance being Fe and inevitable impurities. 2. By weight%, C: 0.02% or less, Si:
0.3-2.0%, Mn: 0.7% or less, P: 0.04% or less, S: 0.005% or less, Ni: 0.3% or less, Cr:
9.0-14.0%, N: 0.02% or less, O: 0.010
% Or less, Al: 2.0% or less, Ti: 5 (C + N) to 0.0.
The content of each component is adjusted so that the F value defined by the following formula is 0 or more and 4 or less, and F value = Cr + Si + 2.1 (Ti + Al) -37.0 (C
+ N) -2.0Ni-0.6Mn-10.8 Soft magnetic stainless steel for relay iron cores with the balance being Fe and inevitable impurities.