JP4669515B2 - Electrical steel sheet component and method for manufacturing the same - Google Patents

Description

  The present invention relates to an electromagnetic steel sheet component and a method for manufacturing the same.

  Conventionally, magnetic steel sheet parts used in electromagnetic products such as electromagnetic relays have been subjected to press-processed magnetic steel sheet base materials for heat treatment for improving magnetic properties and rust prevention treatment for improving electrical properties. Yes. In particular, if the rust prevention treatment is not performed, the weather resistance is lowered and rust is generated, so that good electrical continuity cannot be ensured and it cannot be used as a magnetic steel sheet component. Therefore, since two processing steps of heat treatment and rust prevention treatment are required until the completion of the parts, the production time is very long, and the production cost is a problem.

  As a rust prevention treatment, a plating treatment is generally performed. Specifically, first, a plurality of parts are put in a bowl, the bowl is immersed in a plating bath, and the bowl is rotated in the plating bath. While performing the plating process. However, by rotating the heel, the parts in the heel collide with each other or entangle with each other, affecting the shape of the parts. In particular, a small-sized component is greatly affected when the shape is changed, and as a result, the defect rate of a single component increases. Even if a single component does not result in a failure, the dimensional accuracy of the component itself decreases, so that the variation in characteristics as an electromagnetic relay increases, and the yield as an electromagnetic relay (product) decreases.

  In order to minimize the deterioration of the magnetic properties of the parts after plating, it is common to use Ni as a magnetic material for the plating material. However, even if the Ni plating of the magnetic material is selected, it is inevitable that the magnetic characteristics as a part are deteriorated. For this reason, when the component is used as a movable piece, an iron piece, or a yoke in an electromagnetic relay such as a relay, the operating voltage / return voltage is increased, which adversely affects the performance of the electromagnetic relay.

  Furthermore, Ni plating slides and wears at the sliding portion of the movable piece, and Ni plating wear powder is scattered. As a result, the frictional resistance of the sliding portion increases, the operating voltage / return voltage of the electromagnetic relay using the component increases, and this adversely affects the performance of the electromagnetic relay. In addition, there is a risk of causing poor contact when wear powder adheres to the contacts.

On the other hand, when a specific soft magnetic alloy is oxidized and annealed in an atmosphere with a dew point of 0 to 60 ° C. to form a Fe-based oxide film on the surface, it is reported that weather resistance can be secured even if Ni plating treatment is omitted. (Patent Document 1). However, even with such a technique, sufficient weather resistance cannot be obtained, and rust is likely to occur.
JP-A-8-203718

  An object of the present invention is to provide an electrical steel sheet part having sufficient weather resistance and magnetic properties without having a plating layer, and a method for manufacturing the same.

The present invention relates to the surface of an electrical steel sheet base material comprising Si: 0.20 to 1.20% by weight, Mn: 1.0% by weight or less, Al: 1.0% by weight or less, and the balance: Fe and inevitable impurities. to an electromagnetic steel sheet part comprising a SiO ₂ layer, X (wt%) of Si content in the surface layer comprising an SiO ₂ layer, the Si content in an electromagnetic steel sheet base material and Y (wt%) The electrical steel sheet component is characterized in that X / Y is 5.2 to 11.2.

The present invention also relates to a method for manufacturing an electrical steel sheet component, characterized in that the electrical steel sheet base material is annealed in a gas atmosphere composed of H ₂ and H ₂ O.

The electromagnetic steel sheet component of the present invention has sufficient weather resistance even without a plating layer.
In the present invention, since the plating treatment can be omitted, the following effects are also obtained;
・ Production costs can be reduced.
・ Since a single part can be manufactured with the accuracy as designed, not only the failure rate of a single part can be reduced, but also the yield as an electromagnetic relay (product) can be improved.
- no plating layer, because it has a generally significantly thin SiO ₂ layer from the plating layer thickness (5~8μm) formed, the magnetoresistance is reduced, and excellent magnetic properties. In particular, an electromagnetic relay such as a relay using the component of the present invention as a movable piece can reduce the operating voltage and the return voltage, and the performance of the electromagnetic relay is improved. For example, the magnetic permeability of a component having a Ni plating layer is 8 to 10 μs, whereas the component of the present invention achieves a high magnetic permeability of about 0.5 μs.
-When the component of the present invention is used as a movable piece, the sliding portion of the movable piece does not generate plating layer wear powder and does not increase the frictional resistance. The rise can be prevented more effectively, and contact failure is not caused.

It is a schematic diagram which shows Si atom distribution in the surface vicinity of the electromagnetic steel plate components of this invention. It is a graph which shows roughly the Si content change in the depth direction of the electrical steel sheet components of the present invention. It is a X-ray-diffraction data of the sample produced in the Example. It is a schematic block diagram of the relay which can apply the electromagnetic steel plate components of this invention. It is a composition image photograph by EPMA which shows the metal structure in the surface layer vicinity of the sample 12 (invention). 3 is a composition image photograph by EPMA showing a metal structure in the vicinity of the surface layer of Sample 17. FIG.

Explanation of symbols

1: SiO ₂ layer, 2: base material, 10: movable piece, 10a: horizontal portion, 10b: hanging portion, 10c: sliding portion, 11: coil, 12: card, 13: movable contact piece, 14: movable contact , 15: fixed contact piece, 16: fixed contact.

The magnetic steel sheet component of the present invention has a SiO ₂ layer on the surface of a specific magnetic steel sheet base material.

The magnetic steel sheet base material used in the present invention is:
Si: 0.20 to 1.20% by weight, preferably 0.25 to 1.10% by weight;
Mn: 1.0% by weight or less, preferably 0.05 to 0.5% by weight;
Al: 1.0% by weight or less, preferably 0.01 to 0.50% by weight; and the balance: Fe and inevitable impurities. The electromagnetic steel sheet base material may be a so-called directional electromagnetic steel sheet or non-oriented electromagnetic steel sheet.

If the Si content ratio is too small, the SiO ₂ layer is not effectively formed, so that the weather resistance becomes a problem. Si When the content is too large, not only the surface, and is easily formed the band-shaped SiO ₂ layer slightly deeper from the surface, easily peeled off the surface portion including the SiO ₂ layer of the strip, sufficient weather resistance In addition to being obtained, there is a risk that the powder or flakes generated by peeling off will cause the same adverse effects as the abrasion powder of Ni plating.

When the content ratio of Mn or Al is too large, the SiO ₂ layer is not effectively formed, so that weather resistance becomes a problem.

  The unavoidable impurities are preferably not contained in the present invention, but are atoms that cannot be mixed, and are derived from raw materials and additives used in the production of the magnetic steel sheet base material. Examples of such inevitable impurities include Ni, Cr, C, N, P, and S.

The content of inevitable impurities is not particularly limited, but is usually as shown below;
Ni: 0.1% by weight or less, particularly 0.05% by weight or less;
Cr: 0.1% by weight or less;
C: 0.02% by weight or less;
N: 0.01% by weight or less;
P: 0.2% by weight or less;
S: 0.01% by weight or less.

  In the above composition of the magnetic steel sheet base material, C, N, and S are values measured by gas analysis, and the detection limit value is 0.00001% by weight. Si, Mn, Al, Ni, Cr, and P are values measured by chemical analysis or instrumental analysis equivalent thereto (atomic absorption, X-ray fluorescence, ICP, etc.), and the detection limit is 0.001% by weight. It is.

The thickness of the magnetic steel sheet base material may be appropriately determined according to the intended use of the component to be obtained, and is, for example, 0.5 to 2.0 mm.
In general, the magnetic steel sheet base material is processed into a predetermined shape and cleaned by degreasing prior to an annealing process described later.

The SiO ₂ layer on the surface of the electrical steel sheet base material is manufactured by annealing the electrical steel sheet base material under specific conditions. That is, annealing is performed by holding an appropriate steel plate base material for an appropriate treatment temperature and time in a gas atmosphere composed of H ₂ and H ₂ O. The treatment temperature and holding time are preferably 1100 to 1150 ° C. and 30 to 45 minutes. When annealing is performed, the temperature raising time during which the temperature of the base material is raised from room temperature to the processing temperature is not particularly limited, but is usually preferably 20 to 200 minutes. The temperature lowering time during which the temperature of the base material is lowered from the processing temperature to 80 ° C. is not particularly limited, but is usually preferably 20 to 200 minutes. By such annealing, mechanical strain inside the base material is removed, and Si atoms in the base material are preferentially deposited as SiO _{2 on the} base material surface to form a SiO ₂ layer.

The mixing ratio of H ₂ and H ₂ O in the gas atmosphere for annealing is not particularly limited as long as the object of the present invention is achieved, but a dew point of 30 to 40 ° C. is suitable.
If the mixing ratio of H ₂ O is too small, the SiO ₂ layer is not effectively formed, so that weather resistance becomes a problem. On the other hand, when the mixing ratio of H ₂ O is too large, the formed SiO ₂ layer is easily peeled off, and condensation in the furnace is likely to occur, and the atmosphere in the furnace is likely to be unstable.

Further, when other gases such as N ₂ , O ₂ , Ar, NH _{3 and the} like are mixed in the gas atmosphere, the SiO ₂ layer is not effectively formed, so that the weather resistance becomes a problem.

Formation of the SiO ₂ layer can be confirmed, for example, by subjecting the magnetic steel sheet component sample to thin film X-ray diffraction analysis. A peak of SiO ₂ appears clearly in the X-ray diffraction data (see, for example, FIG. 3).

As long as the object of the present invention is achieved, the present invention does not prevent the SiO ₂ layer from containing elements other than Si shown as the base material composition and oxides thereof. The detailed composition of the SiO ₂ layer can be measured by EPMA, for example, EPMA 1600 manufactured by Shimadzu Corporation. In the present invention, the contents of elements other than Si and O in the SiO ₂ layer are usually determined by the measurement apparatus. It is preferably less than the limit of quantification. The quantitative limit value of the measuring device is 0.1% by weight.

The thickness of the SiO ₂ layer is not particularly limited as long as the object of the present invention is achieved, and is, for example, 0.05 to 0.50 μm, particularly 0.10 to 0.40 μm.
The thickness of the SiO ₂ layer can be measured by repeatedly performing measurement by ESCA and argon ion etching (etching depth: about 10 nm). In the present invention, the thickness of the layer can be determined by repeating the above measurement and etching and assuming that the end point of the SiO ₂ layer is ½ of the O intensity of the outermost surface.

As described above, the SiO ₂ layer is formed by preferentially precipitating Si atoms in the base material as SiO _{2 on the} surface of the base material by annealing, and the source of Si atoms in the SiO ₂ layer is the base material. Therefore, the obtained electrical steel sheet part has a portion where the Si content is less than the base material composition in the depth direction.

As described above, the electromagnetic steel sheet component of the present invention is based on (1) having a SiO ₂ layer on the surface, and (2) a portion where the Si content is smaller than the base material composition in the depth direction. Thus, it is considered to have a Si content distribution as shown below.

The Si content distribution of the electromagnetic steel sheet component will be described in detail with reference to FIG. FIG. 1 is a schematic diagram showing the distribution of Si atoms in the vicinity of the surface of the electromagnetic steel sheet component, and black dots mean Si atoms. Since the electromagnetic steel sheet component has the SiO ₂ layer 1 on the surface, the black spot density is the highest in the surface portion as shown in FIG. The black spot density gradually decreases as the distance from the SiO ₂ layer 1 increases in the depth direction, and then rises again, and then the black spot density in the base material composition 2 is maintained.

FIG. 2 shows the Si content change in the depth direction of the electrical steel sheet component of FIG. In FIG. 2, the Si content maintains the maximum value at the depth of the SiO ₂ layer 1, but decreases as the distance from the surface decreases to a minimum value. After that, after increasing, the value in the base material composition is maintained.
The graph showing the Si content change as shown in FIG. 2 can be created by EPMA.

In the electrical steel sheet component of the present invention, X / Y is 5 when the Si content in the surface layer portion including the SiO ₂ layer is X (wt%) and the Si content in the electrical steel sheet base material is Y (wt%). .2 to 11.2, preferably 5.5 to 10.5, more preferably 6.0 to 10.2. Electrical steel sheet parts having such X / Y values not only have a SiO ₂ layer, but also achieve an optimal Si content distribution and improve the peel resistance of the SiO ₂ layer, thus exhibiting sufficient weather resistance It is considered possible. That is, since the X / electromagnetic steel sheet part having Y is a variation of the Si content just below the SiO ₂ layer is relatively gentle in the Si content distribution in the depth direction, the SiO ₂ layer and the SiO ₂ component of the immediately below the It is considered that the bonding can be effectively achieved and the peeling resistance of the SiO ₂ layer is improved.

If X / Y is too small or too large, desired weather resistance cannot be obtained.
The following reason can be considered as a reason why the weather resistance is poor when X / Y is too small.
-Microscopically, a portion where the SiO ₂ layer is not formed occurs.
· Even defects without the SiO ₂ layer is formed, for X in the surface layer is too small, Si content just below the SiO ₂ layer decreases rapidly in Si content distribution. For this reason, the SiO ₂ layer cannot effectively achieve bonding with the SiO ₂ component immediately below the SiO ₂ layer, and the SiO ₂ layer easily peels off.

The following reason can be considered as a reason why the weather resistance is poor when X / Y is too large.
When · X is too large in the surface layer, SiO ₂ layer becomes thicker. This means that Si atoms in the base material supplied for the formation of the SiO ₂ layer are increased, and a portion where the Si content is smaller than the base material composition is widely generated. As a result, the difference in Si content between the SiO ₂ layer and the portion immediately below it is significantly increased, and the Si content immediately below the SiO ₂ layer in the Si content distribution is sharply reduced. For this reason, the SiO ₂ layer cannot effectively achieve bonding with the SiO ₂ component immediately below the SiO ₂ layer, and the SiO ₂ layer easily peels off.

For the Si content (X) in the surface layer portion including the SiO ₂ layer, the value obtained at the acceleration voltage of 15 kV and the analysis area diameter of 100 μm is used using EPMA1600 manufactured by Shimadzu Corporation. The surface layer portion measured by such a measurement method and measurement condition is a portion from the surface of the electromagnetic steel sheet part to a depth of about 3 μm. Although the thickness of the SiO ₂ layer is as described above, it is Si atoms in the base material that are supplied to the formation of the SiO ₂ layer, and the Si content in the base material is within the above range. For technical reasons, such as being, the thickness of the SiO ₂ layer does not exceed the thickness of the surface layer portion.

  The Si content (Y) in the electrical steel sheet base material may be obtained by measuring in advance the Si content of the electrical steel sheet base material before the annealing treatment, and in the electrical steel sheet part obtained after the processing, May be obtained by measuring a portion excluding the range of about 30 μm in depth. When measuring the Si content of the base material from the electromagnetic steel sheet component, the depth of the measurement exclusion portion is not limited to the above value, and may be a depth where the base material composition remains. In any case, the measurement may be performed using the same measurement method as that for the magnetic steel sheet base material composition described above.

The electrical steel sheet component of the present invention is useful as a component used in an electromagnetic relay such as a relay.
Hereinafter, the case where the electromagnetic steel sheet component of the present invention is used as a movable piece of a relay will be briefly described with reference to FIG.

  FIG. 4 is a schematic configuration diagram of a relay having a basic structure. In FIG. 4, when a voltage is applied to the coil 11, the horizontal portion 10 a of the movable piece 10 is attracted to the coil 11. Accordingly, the hanging portion 10b of the movable piece 10 rotates about the sliding portion 10c as a fulcrum, presses the movable contact piece 13 via the card 12, and the movable contact 14 and the fixed contact piece 15 of the movable contact piece 13 are pressed. Contact with the fixed contact 16 is ensured. On the other hand, when the application of voltage to the coil 11 is stopped, the movable contact 14 is dissociated from the fixed contact 16 by the spring force of the movable contact piece 13, and the drooping portion 10 b of the movable piece 10 is pushed back. Accordingly, the horizontal portion 10 a of the movable piece 10 rotates around the sliding portion 10 c as a fulcrum and moves away from the coil 11.

  In such a relay, for example, since the movable piece rotates around the sliding portion as a fulcrum for a long time, not only excellent magnetic properties but also excellent weather resistance and wear resistance are required. When the electromagnetic steel sheet component of the present invention is used as such a movable piece, the above requirements are satisfied, and the operating voltage / return voltage can be effectively reduced.

  A magnetic steel sheet base material having a composition shown in Table 1 and having a thickness of about 1 mm was punched into a size of 5 mm × 20 mm, and the surface was degreased and cleaned with a hydrocarbon-based cleaning agent. Thereafter, annealing was performed under the conditions shown in Table 2.

The obtained samples were evaluated for the following items.
(Surface composition)
The composition of the surface layer portion of the sample was measured using EPMA1600 manufactured by Shimadzu Corporation described above at an acceleration voltage of 15 kV and an analysis area of φ100 μm.
Moreover, the thin film X-ray diffraction analysis of the sample was performed. In Samples 3 to 5 and 11 to 14 and 17, a clear SiO ₂ peak appeared and the presence of an Fe-based oxide was not recognized. For example, data for samples 3 and 11 are shown in FIG.

(Weatherability)
The weather resistance was evaluated by a pressure cooker test. Specifically, the sample was held for 20 hours under the conditions of a temperature of 125 ° C., a relative humidity of 85%, and an absolute pressure of 2 atm, and the determination was made based on the following criteria based on the degree of surface discoloration.
○: No discoloration at all;
Δ: Discolored but slight;
X: Discoloration was remarkable.

Magnetic properties were evaluated by coercive force. Holding power was measured with K-HC1000 manufactured by TOHOKU STEEL.
In a sample having a conventional Ni plating layer as prepared by the following method, the holding force was 0.76 Oe. Annealing was performed by holding the magnetic steel sheet base material 2 at 850 ° C. for 60 minutes in an H ₂ atmosphere having a dew point of −50 ° C. A plating layer having a thickness of 5 μm was formed on the obtained sample.

(Presence or absence of band-like Si oxide layer directly under the surface)
The cross section of the sample surface layer portion was observed with EPMA (X-ray microanalyzer) to determine the presence or absence of “a strip-like Si oxide layer directly under the surface”. When a band-like Si oxide layer is present immediately below the surface, the surface side is more easily peeled off from the layer. Therefore, even if it has a SiO ₂ layer on the outermost surface and the initial weather resistance is good, the weather resistance deteriorates due to peeling due to long-term use, and sufficient weather resistance cannot be obtained.
The composition image photographs of sample 12 and sample 17 by EPMA are shown in FIGS. 5 and 6, respectively. In addition, an Al protective layer having a thickness of about 1 to 5 μm was formed on the sample before cutting by vapor deposition for the purpose of preventing a loss of the sample surface cross-sectional portion caused by cutting and polishing for obtaining a sample cross section.
It is apparent that the band-like Si oxide layer does not exist immediately below the surface in FIG. 5, but exists immediately below the surface layer in FIG. 5 and 6, the SiO ₂ layer is present on the outermost surface.

Claims (4)

Si: 0.20 to 1.20 wt%, Mn: 1.0 wt% or less, Al: 1.0 wt% or less, and the balance: SiO ₂ layer on the surface of the magnetic steel sheet base material made of Fe and inevitable impurities When the Si content in the surface layer portion including the SiO ₂ layer is X (wt%) and the Si content in the magnetic steel sheet base material is Y (wt%), X / Y is a magnetic steel sheet part characterized by being 5.2 to 11.2.   An electromagnetic relay using the electromagnetic steel sheet component according to claim 1. Si: 0.20 to 1.20% by weight, Mn: 1.0% by weight or less, Al: 1.0% by weight or less, and the balance: magnetic steel sheet base material composed of Fe and unavoidable impurities is H ₂ and H _2. A method for producing an electrical steel sheet part, comprising annealing at a treatment temperature of 1100 to 1150 ° C. in a gas atmosphere comprising O. The manufacturing method of the electrical steel sheet components according to claim 3, wherein annealing is performed at a holding time of 30 to 45 minutes and a dew point of 30 to 40 ° C.