JP7749189B2 - In-plane non-oriented electromagnetic metal plate and its manufacturing method - Google Patents

Description

The present invention relates to an in-plane non-oriented electromagnetic metal plate and a method for manufacturing the same.

Conventional electrical steel sheets are made by combining rolling and heat treatment, strictly controlling the conditions to orient the crystal orientation and improve their magnetic properties. For example, Patent Document 1 discloses a method for manufacturing steel sheets that involves rolling a cast material and heating (heat treating) the rolled material.

Patent Application No. 2015-32147

In recent years, the frequency of the AC power source applied to electrical steel sheets has been increasing, making the magnetic properties near the surface of the sheet particularly important. However, since the crystal orientation of conventional electrical steel sheets is controlled not only near the surface but throughout the entire sheet, including the interior, there is still room for improvement in the magnetic properties near the surface.

In addition, with conventional electrical steel sheets, the management of each manufacturing process is complex. For example, the heat treatment process requires heating to a high temperature (e.g., 1300°C) and holding it there for a long period of time (e.g., 100 hours), which requires a lot of energy to manufacture. Furthermore, to improve the magnetic properties, the composition must be strictly controlled, making it difficult to easily manufacture electrical steel sheets.

The present invention provides an in-plane non-oriented electromagnetic metal plate with controlled crystal orientation and excellent magnetic properties, as well as a method for manufacturing the same.

One aspect of the present invention, an in-plane non-oriented electromagnetic metal plate, has a crystal orientation oriented within the surface of the metal plate.

With the above-mentioned in-plane non-oriented electromagnetic metal plate, the crystal orientation is controlled in a specific direction within the surface of the metal plate. This improves magnetic properties. This makes it suitable for use as an electromagnetic metal plate in motor cores, reactor materials, etc.

In addition, the above-mentioned in-plane non-oriented electromagnetic metal sheet has controlled crystal orientation near the surface of the metal sheet. As a result, it has excellent magnetic properties at high frequencies. This results in superior magnetic properties at high frequencies compared to conventional electromagnetic steel sheets, which are rolled and heat-treated to control the crystal orientation of the entire sheet, not just the surface.

In the above-mentioned in-plane non-oriented electromagnetic metal plate, the <001> direction of the crystals may be aligned approximately parallel to the normal direction to the plate surface. In this case, the <001> direction, which is the axis of easy magnetization of the crystals, can be controlled to be approximately parallel to a predetermined direction, i.e., the normal direction to the plate surface (the direction perpendicular to the surface of the metal plate), thereby improving the magnetic properties.

Furthermore, when measuring the crystal orientation distribution within the surface of the metal plate, the crystal orientation distribution may include at least one peak detected between 0° and 15° from the normal to the plate surface, with a higher intensity than the group of peaks formed between 75° and 105° from the normal to the plate surface, in the <001> direction of the crystal. In this case, the <001> direction, which is the axis of easy magnetization of the crystal, can be controlled to a specified direction, thereby improving magnetic properties.

Furthermore, in the above measurement, the crystal orientation distribution may be such that peak groups are detected in the <111> direction of the crystal between 0° and 15° from the normal to the plate surface and between 39° and 85° from the normal to the plate surface. In this case, the <111> direction, which is the hard magnetization axis of the crystal, can be controlled to a specified direction, thereby improving magnetic properties.

In addition, the crystal orientation may be oriented in at least a portion of the region from the surface of the metal plate to a depth of 100 μm, including the surface of the metal plate. In this case, the crystal orientation can be controlled in the region near the surface of the metal plate, thereby improving the magnetic properties.

The metal material that makes up the metal plate may also be a steel material with a body-centered cubic lattice structure or a body-centered tetragonal lattice structure. In this case, magnetic properties can be further improved. It can also be used as an electromagnetic steel plate for motor cores, reactor materials, etc.

The steel material may also be pure iron. In this case, the magnetic properties can be further improved.

Another aspect of the present invention is a method for manufacturing an in-plane non-oriented electromagnetic metal plate, in which the crystal orientation is oriented within the surface of the metal plate, and a surface processing treatment is performed by projecting a projection material onto the surface of the metal plate.

According to the above-mentioned method for manufacturing in-plane non-oriented electromagnetic metal sheets, the crystal orientation can be easily controlled to a predetermined direction within the surface of the metal sheet by projecting a shot material onto the surface of the metal sheet to perform surface processing. Therefore, compared to conventional electromagnetic steel sheets, which require rolling and heat treatment to control the crystal orientation, there is no need for complex process management. Furthermore, there is no need for high-temperature, long-term heat treatment, which reduces manufacturing energy. This allows for controlled crystal orientation and makes it easy to manufacture electromagnetic metal sheets with excellent magnetic properties.

In addition, the in-plane non-oriented electromagnetic metal sheet manufactured using the above manufacturing method has controlled crystal orientation near the surface of the metal sheet. As a result, it has excellent magnetic properties at high frequencies. This results in superior magnetic properties at high frequencies compared to conventional electromagnetic steel sheets, which are rolled and heat-treated to control the crystal orientation of the entire sheet, not just the surface.

In the above-mentioned method for manufacturing an in-plane non-oriented electromagnetic metal plate, the crystalline orientation state within the surface of the metal plate can be controlled by adjusting at least one of the projection pressure and projection time of the projection material during the surface processing. In this case, the crystalline orientation within the surface of the metal plate can be controlled with high precision.

Furthermore, after the above surface processing, a heat treatment may be performed. In this case, the crystal orientation within the surface of the metal plate can be controlled with high precision.

Furthermore, before carrying out the surface treatment, a lubricant may be applied to at least the area of the surface of the metal plate that will undergo the surface treatment. In this case, friction between the surface of the metal plate and the shot material projected onto the surface of the metal plate during the surface treatment is reduced, allowing for precise control of the crystal orientation within the surface of the metal plate.

The metal material that makes up the metal plate may also be a steel material whose crystal structure is a body-centered cubic lattice structure or a body-centered tetragonal lattice structure. In this case, it is possible to manufacture an electromagnetic steel plate with even better magnetic properties. It is also possible to manufacture an electromagnetic steel plate that is effective for applications such as motor cores and reactor materials.

The steel material may also be pure iron. In this case, it is possible to produce electromagnetic steel sheets with even better magnetic properties.

1 is a scanning electron microscope (SEM) photograph of a sample. 1 is an inverse pole figure (IPF) map obtained by electron backscatter diffraction (EBSD) on a sample. 1 shows (001) and (111) pole figures of the sample obtained by electron backscatter diffraction (EBSD) method. 1 shows (001) and (111) pole figures of the sample obtained by X-ray diffraction (XRD) method. 1 is a scanning electron microscope (SEM) photograph of a sample. 1 is an inverse pole figure (IPF) map obtained by electron backscatter diffraction (EBSD) on a sample. 1 is a scanning electron microscope (SEM) photograph of a sample. 1 is an inverse pole figure (IPF) map obtained by electron backscatter diffraction (EBSD) on a sample. 1 shows (001) and (111) pole figures of the sample obtained by electron backscatter diffraction (EBSD) method. 1 shows (001) and (111) pole figures of the sample obtained by X-ray diffraction (XRD) method. 1 is a scanning electron microscope (SEM) photograph of a sample. 1 is an inverse pole figure (IPF) map obtained by electron backscatter diffraction (EBSD) on a sample. 1 shows (001) and (111) pole figures of the sample obtained by electron backscatter diffraction (EBSD) method. 1 shows (001) and (111) pole figures of the sample obtained by X-ray diffraction (XRD) method. 1 shows (001) and (111) pole figures of the sample obtained by X-ray diffraction (XRD) method. 1 shows (001) and (111) pole figures of the sample obtained by electron backscatter diffraction (EBSD) method. 1 shows (001) and (111) pole figures of the sample obtained by electron backscatter diffraction (EBSD) method.

The following describes an embodiment of the present invention.

[In-plane non-directional electromagnetic metal plate]
First, the in-plane non-oriented electromagnetic metal plate will be described.
In-plane non-oriented electromagnetic metal plates have crystal orientation oriented within the surface plane of the metal plate.

The in-plane non-oriented electromagnetic metal plate can be made of a plate-shaped metal material. Examples of metal materials that can be used include pure iron and iron alloys. Examples of iron alloys that can be used include carbon steel and iron-silicon alloys. Metals other than iron, such as copper, and their alloys, can also be used as metal materials.

In the case of in-plane non-oriented electromagnetic metal sheets, the in-plane surface of the metal sheet where the crystal orientation is oriented refers to the surface layer of the metal sheet (the region near the surface), for example, the region from the surface of the metal sheet to a depth of 100 μm.

In an in-plane non-oriented electromagnetic metal plate, the alignment of the crystal orientation within the surface of the metal plate can be confirmed, for example, by measuring the crystal orientation distribution within the surface of the metal plate. Crystal orientation distribution can be measured using, for example, electron backscatter diffraction (EBSD), which is suitable for measuring localized areas, or X-ray diffraction (XRD), which is suitable for measuring wide-area areas.

In an in-plane non-oriented electromagnetic metal plate, the <001> direction of the crystals may be aligned approximately parallel to the normal to the plate surface. "Approximately parallel" here means, for example, that the <001> direction of the crystals is controlled to an inclination of 0° to 15° relative to the normal to the plate surface.

When measuring the crystal orientation distribution within the surface of a metal plate, the crystal orientation distribution may include at least one peak detected between 0° and 15° from the normal to the plate surface, with a higher intensity than the group of peaks formed between 75° and 105° from the normal to the plate surface, for the <001> direction of the crystal. Here, for crystals whose <001> direction is between 0° and 15° from the normal to the plate surface, another <001> direction is present between 75° and 105° from the normal to the plate surface. Therefore, peaks in the <001> direction of the crystal are formed between 0° and 15° from the normal to the plate surface and between 75° and 105° from the normal to the plate surface.

In the above measurement, the crystal may have a crystal orientation distribution in which peaks are detected in the <111> direction between 0° and 15° from the normal to the plate surface and between 39° and 85° from the normal to the plate surface. Here, for crystals in which the <111> direction is between 0° and 15° from the normal to the plate surface, another <111> direction is located between 55° and 85° from the normal to the plate surface. Furthermore, for crystals in which the <001> direction is located between 0° and 15° from the normal to the plate surface, the <111> direction is located between 39° and 69° from the normal to the plate surface. Therefore, peaks in the <111> direction of the crystal are located between 0° and 15° from the normal to the plate surface and between 39° and 85° from the normal to the plate surface.

In an in-plane non-oriented electromagnetic metal plate, the crystal orientation may be oriented in at least a portion of the region extending from the surface of the metal plate to a depth of 100 μm, including the surface of the metal plate. Here, "at least a portion of the region extending from the surface of the metal plate to a depth of 100 μm, including the surface of the metal plate," may be, for example, a region extending from the surface of the metal plate to a depth of 10 μm, a region extending from the surface of the metal plate to a depth of 50 μm, or a region extending from the surface of the metal plate to a depth of 100 μm.

[Method of manufacturing an in-plane non-oriented electromagnetic metal plate]
Next, a method for manufacturing an in-plane non-oriented electromagnetic metal plate will be described.
The method for manufacturing an in-plane non-oriented electromagnetic metal plate involves projecting a projection material onto the surface of the metal plate to perform a surface processing treatment.

The above-mentioned surface processing can be achieved by projecting a projectile onto the surface of the metal plate, causing the projectile to collide with the surface of the metal plate at high speed, and methods such as shot peening and shot blasting can be used.

The material of the shot material used in the above surface treatment can be selected appropriately depending on the material of the metal plate that is projected and hit. For example, if a steel material is used as the metal material that makes up the metal plate, hard particles such as zircon particles can be used as the shot material.

The conditions for the above surface processing can be adjusted as appropriate. For example, the projection pressure of the projection material, the projection time, the distance between the surface of the metal plate and the projection nozzle that projects the projection material, etc. can be adjusted. By adjusting the projection pressure and projection time of the projection material, the orientation state of the crystal orientation within the surface of the metal plate can be controlled.

Furthermore, after the above surface processing treatment, a heat treatment may be performed. In the heat treatment, the metal plate is heated to a predetermined temperature and held at that temperature for a predetermined period of time. The heat treatment conditions can be adjusted as appropriate, such as the heating temperature and holding time. By adjusting the heat treatment conditions, the crystal orientation within the surface of the metal plate can be precisely controlled.

The heating temperature during heat treatment can be, for example, 400°C to 800°C, and particularly 500°C to 650°C. This eliminates the need for high-temperature heating compared to conventional electrical steel sheet manufacturing, allowing for significant reductions in manufacturing energy. Furthermore, the crystal orientation within the surface of the metal sheet can be precisely controlled.

The holding time (heating time) during heat treatment can be, for example, 0.5 to 10 hours. The holding time during heat treatment can be adjusted appropriately depending on the material of the metal plate, etc., in order to accurately control the crystal orientation within the surface of the metal plate.

In addition, before the surface treatment, a lubricant may be applied to at least the area of the metal plate surface where the surface treatment is to be performed (the processing area). Examples of lubricants that can be applied to the processing area of the metal plate surface include boron nitride (hexagonal boron nitride, etc.), molybdenum disulfide, graphite, and mineral oil.

The present invention will be explained below using examples. However, the present invention is not limited to these examples.

(Example)
<Crystal orientation distribution before shot peening>
First, a sample was prepared. Specifically, a 15 mm × 15 mm sample piece was cut out from a commercially available pure Fe rolled plate having a thickness of 1.5 mm to obtain a metal plate made of pure Fe. The metal plate was then subjected to an annealing treatment at 550°C for 1 hour. In this way, a sample (sample A1) that had been subjected to the annealing treatment and was not yet subjected to shot peening was prepared.

Next, the surface of the sample (Sample A1) was observed using a scanning electron microscope (JEOL Ltd., JIB4600-F). Figure 1 is a scanning electron microscope (SEM) photograph of the sample surface. The SEM photograph in Figure 1 shows that the sample before shot peening had equiaxed crystal grains.

Next, the crystal orientation distribution on the surface of the sample (sample A1) was analyzed using a scanning electron microscope equipped with an electron backscatter diffraction (EBSD) detector (TSL, OIM Data Collection 7). Figure 2 is an inverse pole figure (IPF) map obtained using the EBSD method, showing the crystal orientation distribution on the sample's surface. The IPF map in Figure 2 also shows that the sample before shot peening had equiaxed crystal grains.

Figure 3 shows (001) and (111) pole figures obtained by EBSD, which show the crystal orientation distribution of the <001> and <111> directions of the crystals within the surface of the sample. The pole figures in Figure 3 show that there is no distribution of orientation in either the <001> or <111> directions of the crystals within the surface of the sample, and that the orientation is random.

Next, the surface of the sample (Sample A1) was analyzed using an X-ray diffractometer (Rigaku Corporation, SmartLabo). Figure 4 shows (001) and (111) pole figures obtained by X-ray diffraction (XRD), which show the crystal orientation distribution of the <001> and <111> directions within the surface of the sample. The XRD method can obtain measurement results over a wider range than the EBSD method described above. The pole figure of Figure 3, obtained by measuring a localized region using EBSD, shows no orientation distribution in either the <001> or <111> directions. However, the pole figure of Figure 4, obtained by measuring a wider region using XRD, shows a distribution of orientation in both the <001> and <111> directions, and a rolling recrystallization texture was observed.

<Crystal orientation distribution after shot peening>
Next, the surface of the sample (similar to sample A1) was subjected to shot peening under conditions of a projection pressure of 0.6 MPa and a projection time of 10 minutes. For the shot peening, an air nozzle type shot peening device (Pneumablaster, manufactured by Fuji Manufacturing Co., Ltd.) was used. Zircon particles were used as the shot material (projection material). The distance between the sample surface and the projection nozzle was 30 mm. In this way, a sample (sample A2) after shot peening was prepared.

Next, the processed surface of the sample (sample A2) was observed using a scanning electron microscope. Figure 5 is an SEM photograph showing the cross-sectional microstructure near the processed surface of the sample. Note that the processed surface of the sample refers to the surface of the sample that has been shot peened (the shot-peened surface). The cross section of the sample refers to a cross section along the thickness direction of the sample. The SEM photograph in Figure 5 shows that plastically deformed areas can be seen in the region near the surface of the sample (region A in Figure 5). For example, it can be seen that there is an area that has undergone significant plastic deformation in the surface layer 50 μm to 100 μm deep (the region 50 μm to 100 μm deep from the surface of the sample), but that no significant plastic deformation has occurred further inside.

Next, the machined surface of the sample (sample A2) was analyzed using a scanning electron microscope equipped with an EBSD detector. Figure 6 is an IPF map obtained using the EBSD method, showing the crystal orientation distribution of the cross section near the machined surface of the sample. The IPF map in Figure 6 shows that crystal grain refinement occurs due to shot peening in the region from the machined surface of the sample to a depth of approximately 30 μm (region B in Figure 6). This result suggests that the microstructure of the shot-peened sample changes from the machined surface toward the interior.

Next, the sample (Sample A2) was polished to a depth of 15 μm from the processed surface, and the polished surface (internal processed surface) was observed using a scanning electron microscope. Figure 7 is an SEM photograph of the internal processed surface of the sample. The SEM photograph in Figure 7 also shows that the crystal grains are fine on the internal processed surface 15 μm from the processed surface of the sample, and that significant plastic deformation has occurred.

Next, the internal machined surface of the sample (sample A2) was analyzed using a scanning electron microscope equipped with an EBSD detector. Figure 8 is an IPF map obtained using the EBSD method, showing the crystal orientation distribution of the internal machined surface of the sample. The IPF map in Figure 8 also shows that the crystal grains are fine on the internal machined surface 15 μm inside the machined surface of the sample.

Figure 9 also shows (001) and (111) pole figures obtained by EBSD, showing the crystal orientation distribution of the <001> and <111> directions of the crystals on the internal machined surface of the sample. The pole figures in Figure 9 reveal that the <001> direction, the easy axis of magnetization of Fe, is strongly oriented and distributed so as to be approximately parallel to the normal to the plate surface of the machined surface, as shown in the schematic diagram in the lower right of Figure 9 . It also reveals that the <001> direction, the easy axis of magnetization, is oriented approximately parallel to the normal to the plate surface of the machined surface, while the other <001> directions are randomly distributed within the machined surface. That is, the peak with the highest intensity in the <001> direction, the easy axis of magnetization, is strongly oriented and distributed between 0° and 15° from the normal to the plate surface of the machined surface, specifically at an angle of approximately 11° from the normal to the plate surface. Additionally, the other <001> direction is strongly and randomly oriented between 75° and 105° from the normal to the plate surface of the processed surface, specifically between approximately 79° and 101° from the normal to the plate surface. Furthermore, although slightly less so than the <001> direction, the <111> direction, which is the hard magnetization axis, is also weakly oriented parallel to the normal to the plate surface of the processed surface, similar to the <001> direction. Specifically, peaks for the <111> direction, which is the hard magnetization axis, are formed between 0° and 15° from the normal to the plate surface and between 39° and 85° from the normal to the plate surface.

Next, the sample (Sample A2) was analyzed using a powder X-ray diffractometer. Figure 10 shows the (001) and (111) pole figures obtained by XRD, which show the crystal orientation distribution of the <001> and <111> directions of the crystals on the processed surface of the sample. The pole figures in Figure 10 also reveal that the <001> direction, which is the axis of easy magnetization, is parallel to the normal to the processed surface, while the other <001> directions are strongly oriented randomly within the processed surface. Furthermore, the <111> direction, which is the axis of hard magnetization, is weakly oriented parallel to the normal to the processed surface, similar to the <001> direction. Therefore, the results obtained by XRD (Figure 10) are consistent with the results obtained by EBSD (Figure 9). This crystal orientation distribution is similar to that of non-oriented electrical steel sheet and is expected to improve the magnetic properties of Fe (iron).

<Effect of Shot Peening Pressure on Crystal Orientation Distribution after Shot Peening>
The surface of a sample (similar to sample A1) that had been annealed at 550°C for 1 hour was subjected to shot peening under conditions of blasting pressures of 0.2 MPa and 0.6 MPa and a blasting time of 10 minutes. An air nozzle type shot peening device was used for the shot peening. Zircon particles were used as the shot material. The distance between the sample surface and the blasting nozzle was 30 mm. This produced a shot-peened sample (sample A3).

Next, the sample (sample A3) was polished to a depth of 15 μm from the processed surface, and the polished surface (internal processed surface) was observed using a scanning electron microscope. Figure 11 is an SEM photograph of the sample's internal processed surface. The SEM photograph in Figure 11 shows that the internal processed surface 15 μm from the sample's processed surface had fine crystal grains and large plastic deformation, in both samples that were shot peened at a projection pressure of 0.2 MPa and 0.6 MPa.

Next, the internal machined surface of the sample (sample A3) was analyzed using a scanning electron microscope equipped with an EBSD detector. Figure 12 is an IPF map obtained using the EBSD method, showing the crystal orientation distribution of the internal machined surface of the sample. The IPF map in Figure 12 also shows that the crystal grains are fine on the internal machined surface 15 μm inside the machined surface of the sample.

Figure 13 shows (001) and (111) pole figures obtained by EBSD, showing the distribution of the crystal orientations of the <001> and <111> directions of the crystals on the internal machined surface of the sample. The pole figures in Figure 13 reveal that the sample shot peened at a projection pressure of 0.2 MPa retained some rolling recrystallization texture, while the sample shot peened at a projection pressure of 0.6 MPa exhibited a strong orientation distribution of the highest intensity peak of the <001> direction (the axis of easy magnetization) between 0° and 15° from the normal to the machined surface, specifically at an angle of approximately 11° from the normal to the surface. Furthermore, the other <001> direction exhibited a strong orientation distribution between 75° and 105° from the normal to the machined surface, specifically at an angle of approximately 79° and 101° from the normal to the surface. This shows that the crystal orientation distribution of pure Fe can be controlled by adjusting the projection pressure of the projection material.

Next, the surface of a sample (similar to sample A1) that had been annealed at 550°C for 1 hour was shot peened at a projection pressure of 0.2 MPa and 0.6 MPa for a projection time of 30 minutes. An air nozzle-type shot peening device was used for the shot peening. Zircon particles were used as the shot material. The distance between the sample surface and the projection nozzle was 30 mm. This resulted in the preparation of a shot-peened sample (sample A4).

Next, the sample (Sample A4) was analyzed using a powder X-ray diffractometer. Figure 14 shows the (001) and (111) pole figures obtained by XRD, which show the crystal orientation distribution of the <001> and <111> directions of the crystals on the processed surface of the sample. The pole figures in Figure 14 reveal that for both samples shot peened at 0.2 MPa and 0.6 MPa, the <001> direction, the axis of easy magnetization, is parallel to the normal to the processed surface, while the other <001> directions are strongly oriented randomly within the processed surface. Therefore, it can be said that longer shot peening times result in a crystal orientation distribution that improves the magnetic properties of pure Fe, even at lower peening pressures. However, when shot peening is performed with a blasting pressure of 0.6 MPa for a blasting time of 30 minutes, the orientation in which the <111> direction, the hard magnetization axis, is parallel to the normal direction of the processed surface is stronger than when the blasting time is 10 minutes. Therefore, this crystal orientation distribution of pure Fe can be controlled by the blasting pressure and blasting time.

<Effect of Shot Peening Time on Crystal Orientation Distribution after Shot Peening>
The surface of a sample (similar to sample A1) that had been annealed at 550°C for 1 hour was subjected to shot peening at a projection pressure of 0.6 MPa for a projection time of 5 to 30 minutes (5 minutes, 10 minutes, 30 minutes). An air nozzle type shot peening device was used for the shot peening. Zircon particles were used as the shot material (projection material). The distance between the sample surface and the projection nozzle was 30 mm. This produced a shot-peened sample (sample A5).

Next, the sample (Sample A5) was analyzed using a powder X-ray diffractometer. Figure 15 shows the (001) and (111) pole figures obtained by XRD, which show the crystal orientation distribution of the <001> and <111> directions of the crystals on the processed surface of the sample. The pole figures in Figure 15 reveal that as the projection time increases, the orientation distribution first becomes stronger, with the <001> direction (the easy axis of magnetization) parallel to the normal to the processed surface, while the other <001> directions become random within the processed surface. Then, the orientation distribution becomes stronger, with the <111> direction (the hard axis of magnetization) parallel to the normal to the processed surface. Therefore, shot peening of pure Fe first forms a texture in which the <001> direction is parallel to the normal to the processed surface, and then a texture in which the <111> direction is parallel to the normal to the processed surface also forms. Therefore, an appropriate projection time is required to improve the magnetic properties of pure Fe.

<Effects of heat treatment after shot peening>
Here, a sample that was not subjected to heat treatment after shot peening (sample A6) and a sample that was subjected to heat treatment after shot peening (sample A7) were prepared and compared to confirm the effect of the heat treatment after shot peening.

To prepare sample A6, the surface of a sample (similar to sample A1) that had been annealed at 550°C for 1 hour was subjected to shot peening at a projection pressure of 0.6 MPa for a projection time of 10 minutes. An air nozzle type shot peening device was used for the shot peening. Zircon particles were used as the shot material. The distance between the sample surface and the projection nozzle was 30 mm. This resulted in the preparation of sample A6, which was not subjected to heat treatment after shot peening.

To prepare sample A7, the surface of a sample (similar to sample A1) that had been annealed at 550°C for 1 hour was subjected to shot peening at a projection pressure of 0.6 MPa for a projection time of 10 minutes. An air nozzle-type shot peening device was used for the shot peening. Zircon particles were used as the shot material. The distance between the sample surface and the projection nozzle was 30 mm.

The shot-peened sample was then subjected to heat treatment. During heat treatment, the sample was heated to a specified temperature and held for a specified period of time. The heating temperature was set to an optimum value within the range of 500°C to 650°C. The holding time (heating time) was set to an optimum value within the range of 0.5 to 5 hours. In this way, sample A7, which had been heat-treated after shot peening, was produced.

Next, samples A6 and A7 were polished 15 μm inward from the processed surface, and the polished surfaces (internal processed surfaces) were analyzed using a scanning electron microscope equipped with an EBSD detector. Figure 16 shows (001) and (111) pole figures obtained by the EBSD method, showing the crystal orientation distribution of the <001> and <111> directions of the crystals on the internal processed surfaces of samples A6 and A7.

The pole figures in Figure 16 show that for both sample A6, which was not heat-treated after shot peening, and sample A7, which was heat-treated after shot peening, the <001> direction, which is the axis of easy magnetization, is parallel to the normal direction to the plate surface of the processed surface, and the other <001> directions are strongly oriented and distributed randomly within the processed surface.

Comparing the two, sample A7, which underwent heat treatment after shot peening, shows a stronger orientation distribution in which the <001> direction, the axis of easy magnetization, is parallel to the normal to the processed surface, and the other <001> directions are random within the processed surface, compared to sample A6, which was not heat treated after shot peening. It also shows a weaker orientation distribution in which the <111> direction, the axis of hard magnetization, is parallel to the normal to the processed surface. Thus, by performing heat treatment after shot peening, it is possible to produce a sample with an orientation distribution in which only the <001> direction, the axis of easy magnetization, is parallel to the normal to the processed surface, and with minimal lattice defects within the sample. This allows for precise control of the crystal orientation within the sample surface, further improving magnetic properties.

<Effect of applying lubricant before shot peening>
Here, a sample (sample A8) to which no lubricant was applied before shot peening and a sample (sample A9) to which a lubricant was applied before shot peening were prepared and compared to confirm the effect of applying a lubricant before shot peening.

To prepare sample A8, the surface of a sample (similar to sample A1) that had been annealed at 550°C for 1 hour was subjected to shot peening at a projection pressure of 0.6 MPa for a projection time of 15 minutes. An air nozzle type shot peening device was used for the shot peening. Zircon particles were used as the shot material. The distance between the sample surface and the projection nozzle was 30 mm. This resulted in the preparation of sample A8, which was not coated with a lubricant before shot peening.

To prepare sample A9, a sample (similar to sample A1) was annealed at 550°C for 1 hour, and a lubricant was applied to the area (machined area) on the surface where shot peening would be performed. Boron nitride was used as the lubricant.

The lubricant-coated surface of the sample was then subjected to shot peening at a projection pressure of 0.6 MPa for a projection time of 15 minutes. An air nozzle-type shot peening device was used for the shot peening. Zircon particles were used as the shot material. The distance between the sample surface and the projection nozzle was 30 mm. This resulted in the production of sample A9, which had been coated with lubricant before shot peening.

Next, samples A8 and A9 were polished to a depth of 15 μm from the processed surface, and the polished surfaces (internal processed surfaces) were analyzed using a scanning electron microscope equipped with an EBSD detector. Figure 17 shows (001) and (111) pole figures obtained by the EBSD method, showing the crystal orientation distribution of the <001> and <111> directions of the crystals on the internal processed surfaces of samples A8 and A9.

From the pole figures in Figure 17, it can be seen that for both sample A8, which was not lubricated before shot peening, and sample A9, which was lubricated before shot peening, the <001> direction, which is the axis of easy magnetization, is parallel to the normal direction to the plate surface of the processed surface, and the other <001> directions are strongly oriented and distributed randomly within the processed surface.

Furthermore, comparing the two, sample A9, which was lubricated before shot peening, shows a stronger orientation distribution in which the <001> direction, the axis of easy magnetization, is parallel to the normal to the processed surface, and the other <001> directions are random within the processed surface, compared to sample A8, which was not lubricated before shot peening. It also shows a weaker orientation distribution in which the <111> direction, the axis of hard magnetization, is parallel to the normal to the processed surface. Thus, applying a lubricant before shot peening reduces friction between the sample surface and the shot material projected onto it during shot peening. As a result, the plastic deformation occurring on the sample surface during shot peening has a smaller shear component and a larger compressive component. This allows for precise control of the crystal orientation within the sample surface, further improving magnetic properties.

(Other embodiments)
The present invention is not limited to the above-described embodiments (examples), and it goes without saying that the present invention can be embodied in various forms without departing from the scope of the present invention.

The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to, replaced with, or the like, the configuration of another of the above embodiments. Note that all aspects included in the technical idea identified by the wording of the claims are embodiments of the present invention.

Claims (6)

the <001> direction of the crystals in the surface plane of the metal plate made of pure iron is aligned approximately parallel to the normal direction of the plate surface,
In measuring the crystal orientation distribution within the surface of the metal plate, in a (001) pole figure showing the crystal orientation distribution in the <001> direction of the crystal, at least one peak having a higher intensity than a group of peaks formed between 75° and 105° from the normal direction to the plate surface is detected between 0° and 15° from the normal direction to the plate surface.
In-plane non-directional electromagnetic metal plate. In the measurement, in a (111) pole figure showing the crystal orientation distribution in the <111> direction of the crystal, a group of peaks formed between 0° and 15° from the normal direction to the plate surface and between 39° and 85° from the normal direction to the plate surface is detected. The in-plane non-oriented electromagnetic metal sheet according to claim 1, wherein the crystal orientation distribution is such that a group of peaks formed between 0° and 15° from the normal direction to the plate surface and between 39° and 85° from the normal direction to the plate surface. An in-plane non-oriented electromagnetic metal plate according to claim 1 or 2, wherein the crystal orientation is oriented in at least a portion of the region extending from the surface of the metal plate to a depth of 100 μm, including the surface of the metal plate. A method for manufacturing an in-plane non-oriented electromagnetic metal plate in which the <001> direction of the crystal is aligned approximately parallel to the normal direction of the plate surface within the surface of the metal plate made of pure iron,
a surface treatment process is performed by projecting a projectile onto the surface of the metal plate by shot peening;
After the surface processing treatment, the metal plate is further subjected to heat treatment.
Method for manufacturing in-plane non-oriented electromagnetic metal sheets. The method for manufacturing an in-plane non-oriented electromagnetic metal plate according to claim 4, wherein at least one of the projection pressure and projection time of the projection material during the surface processing is adjusted to control the in-plane orientation of the crystal orientation on the surface of the metal plate. The method for manufacturing an in-plane non-oriented electromagnetic metal plate according to claim 4 or 5, wherein a lubricant is applied to at least the area of the surface of the metal plate to be subjected to the surface treatment before the surface treatment is performed.