JP2638180B2 - Low iron loss unidirectional silicon steel sheet and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a unidirectional silicon steel sheet having a low iron loss, in particular, by subdividing magnetic domains by press-fitting a coating on a steel sheet surface into ground iron, It is intended to reduce iron loss.

(Prior Art) Secondary recrystallized grains of a product of a unidirectional silicon steel sheet are highly integrated in a Goss orientation, and a forsterite coating is formed on the surface of the steel sheet, and the thermal expansion coefficient is small thereon. It is coated with an insulating film, and is manufactured through complicated and various processes that require strict control.

The grain oriented silicon steel sheet as mainly transformers, are used as the iron core and other electrical equipment, (represented by ₁₀ values B) flux density of the product as the magnetic properties are high, the iron loss (W _{17 /} (Represented by ₅₀ values) and an insulating coating having good surface properties.

In particular, there has been a remarkable demand for reducing power loss after the energy crisis, and the necessity of a unidirectional silicon steel sheet having a lower core loss than that of a core material for transformers has been increasing.

By the way, it is not an exaggeration to say that the history of the iron loss improvement of the unidirectional silicon steel sheet is the history of the improvement of the Goss orientation secondary recrystallization texture. As a method of controlling such secondary recrystallized grains, a method of preferentially growing the Goss orientation secondary recrystallized grains using a primary recrystallized grain growth inhibitor such as AIN, MnS and MnSe, a so-called inhibitor, has been implemented. ing.

On the other hand, a method completely different from the method of controlling these secondary recrystallization textures, that is, laser irradiation on the surface of the steel sheet. Tadashi Ichiyama: Iron and Steel, 69 (1983), P.895, Japanese Patent Publication No. 57-2252,
No. 57-53419, refer to the respective publications or plasma irradiation {refer to JP-A Nos. 62-96617, 62-151511, 62-151516 and 62-151517, and introduce local micro-strains. Innovative methods have been proposed to subdivide magnetic domains and thereby reduce iron loss. However, the steel sheet obtained by these methods has a drawback that it cannot be used as a material for a wound iron core transformer subjected to high-temperature strain relief annealing because the micro strain disappears when heated to a high temperature range.

A method has been proposed in which iron loss does not deteriorate even when such high-temperature strain relief annealing is performed. For example, a method of forming grooves or serrations on the surface of a finish-annealed plate (Japanese Patent Publication No.
No. 35679, JP-A-59-28525 and JP-A-59-197520), a method of forming a fine recrystallized grain region on the surface of a finish-annealed plate (see JP-A-56-130454), A method of forming a different thickness or defective area in a coating (Japanese Patent Application Laid-Open
-92479, 60-92480, 60-92481 and 60-2
58479), a method of forming a heterogeneous composition region in ground iron, a forsterite coating or a tension insulating coating (see JP-A-60-103124 and JP-A-60-103182). is there.

However, all of these methods have not been industrially adopted, because the effect of reducing iron loss is small in spite of the complicated steps and the production cost is high.

(Problems to be Solved by the Invention) The present invention relates to a low iron loss unidirectional silicon in which iron loss reduced by domain refining does not deteriorate even when subjected to strain relief annealing, and can be manufactured stably. It is an object of the invention to propose a steel sheet and a method for advantageously producing this steel sheet.

(Means for Solving the Problems) The present invention provides a unidirectional silicon steel sheet having a forsterite coating subjected to finish annealing or an insulating coating further formed on the forsterite coating to form a forsterite on the steel sheet surface. A low iron loss unidirectional silicon steel sheet obtained by locally introducing a micro-pressed region in which a porous coating or a forsterite-based coating and an insulating coating are pressed into the base iron in a direction orthogonal to the rolling direction of the steel sheet.

In particular, it is advantageous that the press-fitted area on the steel sheet surface extends through the ground iron to the coating on the backside of the steel sheet. A minute convex portion corresponding to the portion is formed.

Further, the steel sheet according to the present invention is subjected to finish annealing of a unidirectional silicon steel sheet, and on the front thereof, an electron beam generated at an acceleration voltage of 100 to 500 kV and an acceleration current of 0.005 to 10 mA in a direction perpendicular to the rolling direction. It can be advantageously produced by irradiating the steel sheet and press-fitting the coating on the surface of the steel sheet into the base steel, or by pressing the base iron into the coating on the back surface of the steel sheet.

Further, by changing the irradiation diameter and the irradiation interval of the electron beam so as to sandwich the space between the minute press-fitted regions, it is possible to promote magnetic domain subdivision.

(Operation) Next, the present invention will be described in detail based on embodiments.

C: 0.043wt% (hereinafter simply referred to as%), Si: 3.45%, Mn: 0.0
A silicon steel slab containing 68%, Se: 0.022%, Sb: 0.025%, Mo: 0.013% is heated at 1380 ° C for 4 hours, and then hot-rolled to 2.2m.
After forming a hot-rolled sheet having a thickness of m, the sheet was twice cold-rolled with intermediate annealing at 980 ° C for 120 minutes to obtain a final cold-rolled sheet of 0.20 mm.
Then, after decarburizing primary recrystallization annealing in wet hydrogen at 820 ° C., an annealing separator containing MgO as a main component is applied to the surface of the steel sheet by slurry, and then, secondary recrystallization annealing at 850 ° C. for 50 hours is performed. And then preferentially grow Goss orientation secondary recrystallized grains.
The sample was subjected to purification annealing in dry hydrogen at 5 ° C. for 5 hours to obtain a sample (A). A part of the sample (A) was formed as a sample (B) by forming an insulating coating mainly containing phosphate and colloidal silica on the surface of the steel sheet. Thereafter, minute press-fit regions or minute strains extending in a direction perpendicular to the rolling direction were introduced into the samples (A) and (B) at intervals of 8 mm by the following means (1) to (3).

(1) Knife (2) YAG laser irradiation (Irradiation conditions: energy per spot 4 × 10 ^-3 J, spot diameter 0.15 mm, spot center interval 0.3 mm, scan interval 8 m
m) (3) Electron beam (hereinafter referred to as EB) irradiation (irradiation conditions: acceleration voltage 100 kV, current 0.7 mA, spot diameter 1.
(4 mm) EB irradiation (irradiation conditions: acceleration voltage 100 kV, current 0.3 mA, spot diameter 0.
(15 mm, spot center interval 0.3 mm, scanning interval 8 mm) After performing the above treatment, each sample was subjected to strain relief annealing at 800 ° C. for 2 hours. Table 1 shows the magnetic properties of the sample after the strain relief annealing.

For comparison, the properties of the untreated material (without strain introduction and with strain relief annealing) are also shown in the table.

As is clear from the table, both samples (A) and (B) had an iron loss of 0.05 in the treatment under the conditions (3) and (4).
It can be seen that it is greatly improved to ~ 0.08 W / kg.

In addition, in the steel sheet treated under the condition (4), a minute press-fitting region was introduced to the back surface of the steel sheet from a place where a minute projection was found on the back surface.

Now, the reason why the iron loss of the sample treated under the treatment condition (3) is improved as compared with the other ones is as shown in FIG.
Forsterite coating 1 and insulating coating 2 on steel sheet surface
Is pressed into the ground iron 3 (secondary recrystallized with Goss orientation) in the microscopic direction in the minute direction, so that it acts as an effective magnetic domain refining nucleus even when subjected to strain relief annealing, enabling magnetic domain refining. Because it became.

The reason why the iron loss of the sample treated under the treatment condition (4) is greatly improved as compared with the other ones is that, as shown in FIG. Since it penetrates to the coating on the back surface of the steel sheet, it acts as a stronger magnetic domain refinement nucleus.

In addition, in order to press the base coat and the insulating coat deep in the steel plate in the width direction of the steel sheet in the minute region, it becomes possible only by using high voltage and low current EB.
That is, particularly when high voltage and low current EBs are used, as shown in FIG. 2, the penetration force in the depth direction is stronger than other methods (laser, plasma, mechanical method). In addition, since it penetrates in the narrowest width, it can be pushed into the base steel without losing the base coat and the insulating coat.

Further, an experiment performed on EB irradiation conditions will be described.

C: 0.042%, Si: 3.42%, Mn: 0.072%, Se: 0.021%, Sb: 0.
A silicon steel slab containing 023% and Mo: 0.013%
After heating for 2 hours, hot rolling was performed to form a 2.2 mm thick hot rolled sheet, and then 9
Cold rolling was performed twice with intermediate annealing at 80 ° C. for 120 minutes to obtain a final cold-rolled sheet of 0.20 mm. Then, after decarburizing primary recrystallization annealing in wet hydrogen at 820 ° C., an annealing separating agent containing MgO as a main component is slurry-coated on the surface of the steel sheet, and then 850 ° C.
After performing secondary recrystallization annealing at 50 ° C. for 50 hours to grow secondary recrystallized grains in the Goss orientation preferentially, purification annealing was performed in dry hydrogen at 1200 ° C. for 5 hours to obtain a sample (A). A part of the sample (A) was formed as a sample (B) by forming an insulating coating mainly containing phosphate and colloidal silica on the surface of the steel sheet. Thereafter, minute press-fit regions extending in the direction perpendicular to the rolling direction were introduced into the samples (A) and (B) at intervals of 8 mm by the following means (1) to (3).

(1) EB irradiation (irradiation conditions: acceleration voltage 150 kV, current 1.5 mA, spot diameter 0.
EB irradiation on the steel sheet surface is as shown in Fig. 3 (a), 12mm, spot center interval 0.3mm, scanning interval 8mm.
The irradiation diameter at each spot and the irradiation interval between the spots were made uniform. FIG. 3B shows the intensity of the EB at each spot as the height of a triangle, and FIG. 3C shows the EB scanning time on the horizontal axis and the displacement of one EB scanning on the vertical axis.

(2) EB irradiation (irradiation conditions: acceleration voltage 150 kV, current 1.5 mA or 0.75 mA, spot diameter 0.12 mm or 0.80 mm, spot center interval 0.3
mm, scanning interval 8 mm) The EB irradiation on the steel sheet surface is performed while changing the current alternately between 1.5 mA and 0.75 mA to change the irradiation diameter and the irradiation interval, as shown in FIG. Irradiation marks were applied.
FIGS. 3 (b) and 3 (c) are similar to FIG.
5 shows changes in the EB irradiation position with respect to changes in EB intensity and EB scanning time.

(3) EB irradiation (irradiation conditions: acceleration voltage 150 kV, current 1.5 mA or 0.75 mA, spot diameter 0.12 mm or 0.80 mm, spot center interval 0.3
mm, scanning interval 8mm) The EB irradiation on the steel sheet surface is performed while changing the current alternately between 1.5mA and 0.75mA to change the irradiation diameter and the irradiation interval, as shown in Fig. 5 (a). Irradiation marks were applied.
FIGS. 3 (b) and 3 (c) are similar to FIG.
The change of the irradiation position of EB with respect to the EB intensity and the time change of EB is shown.

After performing the above treatment, each sample was subjected to strain relief annealing at 800 ° C. for 2 hours. Table 2 shows the magnetic properties of the sample after the strain relief annealing.

In addition, for comparison, untreated material (without introduction of micro press-in area,
The characteristics of “with strain relief annealing” are also shown in the table.

As is clear from the table, both samples (A) and (B)
Iron loss is 0.05 ~ 0.11W /
kg, and especially in the treatments (2) and (3), iron loss is reduced to 0.
It can be seen that it is significantly improved from 10 to 0.11 W / kg. Furthermore, the space factor of the product was good, 96.6-96.8%.

In addition, the transmission power of EB in the thickness direction (depth direction) of a silicon steel sheet is not usually used because a large amount of X-rays are generated.
Increase at accelerating voltages above 65kV, especially 100kV
From the above, it was also found that the permeability increased remarkably. Normally, the acceleration voltage of EB used for welding is
Since it is limited to 60 kV or less, its permeation power is extremely small, so that this effect could not be conventionally found or used. Therefore, in order to make the most of the effects of the present invention, it is important to use a high acceleration voltage (100 to 500 kV) and a small acceleration current (0.001 to 5 mA). Is increased. Further, in order to efficiently perform magnetic domain subdivision, it is preferable that the irradiation region is made to have a size of 0.5 mmφ or less by using a thin EB. Furthermore, after the EB irradiation, an insulating film may be applied thereon to further enhance the insulating properties on the EB irradiation traces, but the cost is increased, so that the insulating effect can be sufficiently exhibited without the EB irradiation.

Further, as described above, the steel sheet according to the present invention can be used for a laminated iron core or a wound iron core, but when providing a laminated iron core material, it is necessary to introduce a fine press-in area smaller than the wound iron core material. It is preferable that the EB irradiation conditions are such that the current is small and the scanning interval is wide. On the other hand, the EB irradiation condition when used for wound iron core material is to slightly increase the current and narrow the scanning interval to promote the introduction of micro-strain on the steel sheet surface so that the characteristics are not deteriorated even after performing the strain relief annealing. Is preferred.

(Examples) Example 1 (A) C: 0.043%, Si: 3.36%, Se: 0.02%, Sb: 0.025
%, Mo: 0.013% or (B) C: 0.063%, Si: 3.42%, Al:
Finished annealed sheet (0.20 mm thick) of silicon steel containing 0.025%, S: 0.023%, Cu: 0.05%, and Sn: 0.1% each with a forsterite coating and a steel sheet coated with an insulating coating on its surface Then, EB irradiation extending in a direction perpendicular to the rolling direction was performed using an EB apparatus. The EB irradiation conditions were as follows: acceleration voltage: 100 kV,
The acceleration current was 0.5 mA, the spot diameter was 0.1 mm, the center interval between the spots was 0.3 mm, and the scanning interval was 8 mm. The minute press-fit area was not introduced into the coating on the back surface of the steel sheet.

The treated product was subjected to strain relief annealing at 800 ° C for 2 hours. As shown in Table 3, the magnetic properties of the treated product were lower than those of the comparative material (without introduction of a small press-in area and with strain relief annealing). The loss was reduced by about 0.08 to _0.1 w / kg in _W17 / ₅₀ value.

Example 2 (A) C: 0.042%, Si: 3.38%, Se: 0.023%, Sb: 0.026%
%, Mo: 0.012% or (B) C: 0.061%, Si: 3.44%, Al:
For annealed sheets (0.20 mm thick) of silicon steel with a forsterite coating containing 0.026%, S: 0.028%, Cu: 0.08%, and Sn: 0.15%, respectively, and a steel sheet coated with an insulating coating on its surface Then, EB irradiation extending in a direction perpendicular to the rolling direction was performed using an EB apparatus. The EB irradiation conditions were as follows: scanning voltage according to FIG. 5, acceleration voltage: 150 kV, acceleration current: 1.5 mA, spot diameter:
The distance was 0.1 mm or 0.7 mm, the center interval of the spots was 0.3 mm, and the scanning interval was 8 mm. The minute press-fit area was introduced to the coating on the back surface of the steel sheet.

Next, the treated product was subjected to a strain relief annealing at 800 ° C. for 2 hours. As shown in Table 4, the magnetic properties of the treated product were lower than those of the comparative material (without introduction of a small press-in area and with strain relief annealing). Iron loss was reduced by about 0.10 to 0.14 w / kg in W17 / ₅₀ value.

Example 3 C: 0.068%, Si: 3.39%, Mn: 0.082%, Se: 0.019%, Al:
A hot rolled silicon steel sheet containing 0.023%, Sb: 0.022% and Mo: 0.012% was subjected to two cold rolling steps with intermediate annealing at 1050 ° C to form a final cold-rolled sheet having a thickness of 0.23mm, and then 840 ° C. After decarburizing, the temperature was raised from 850 ° C. to 1050 ° C. at 10 ° C./h to develop secondary recrystallized Goss grains, followed by annealing at 1230 ° C. in dry H ₂ . Thereafter, an insulating coating mainly composed of phosphate and colloidal silica was further applied thereon, and high-voltage / low-current EB irradiation shown in Table 5 was performed in a direction perpendicular to the rolling direction. The magnetic properties of the product at that time are shown together,
80 for all products except some samples (indicated by * in the table)
The strain relief annealing was performed at 0 ° C. for 2 hours. The spot diameter of the electron beam at this time is 0.10 to 0.12 mm and the scanning interval is
Performed at 7 mm.

Example 4 C: 0.044%, Si: 3.45%, Mn: 0.073%, Se: 0.020%, S
b: 0.026%, Mo: 0.014% containing hot rolled silicon steel sheet at 950 ° C
The final cold rolled sheet with a thickness of 0.20 mm was formed by cold rolling twice with intermediary annealing, followed by decarburization and primary recrystallization annealing at 800 ° C, followed by secondary recrystallization at 850 ° C for 50 hours. After annealing to develop secondary recrystallized Goss grains, dry at 1180 ° C for 8 hours.
It was slowed annealing in H _2. After that, an insulating coating mainly composed of phosphate and colloidal silica is applied to the surface, and then (a) 330 kV, 0.5 mA, (b) 64
After EB irradiation at 0 kV and 0.4 mA, strain relief annealing was performed at 800 ° C. for 3 hours. The spot diameter of the electron beam is 0.08mm
And the scan interval was 7 mm. The magnetic properties of the product at this time are (a) B ₁₀ = 1.92 T, W17 _17/50 = 0.74 W / kg, (b) B ₁₀ = 1.92 T, W17 _17/50 = 0.72 W / kg, Products that do not undergo EB irradiation after the process (B ₁₀
= 1.92T, W _17/50 = _0.92W / kg) showed a significant improvement in iron loss by 20 to 22%.

Example 5 C: 0.042%, Si: 3.32%, Mn: 0.068%, Se: 0.019%, S
b: 0.022%, Mo: 0.011% silicon steel slab containing 1350
After heating at 4 ° C. for 4 hours, hot rolling was performed to a thickness of 2.4 mm, and then intermediate rolling at 980 ° C. was performed, followed by cold rolling twice to obtain a final cold rolled sheet having a thickness of 0.20 mm. After that, primary recrystallization annealing, which also serves as decarburization, was performed in 820 ° C wet hydrogen.
Secondary recrystallization annealing was performed for 0 hours, followed by annealing in dry H ₂ at 1200 ° C. for 5 hours. After that, the oxide on the steel sheet surface was removed, and the center line average roughness (R _a ) was 0.08 by electrolytic polishing.
After finishing to a thickness of μm, TiN was formed in a thickness of 1.0 μm by ion plating (HCD method). Further, an insulating coating mainly composed of phosphate and colloidal silica was formed thereon, and then irradiated with high-voltage / low-current EB (condition: 225 kV, 0.5 mA) in a direction perpendicular to the rolling direction. The electron beam spot diameter was 0.11 mm and the scanning interval was 6 mm.

Magnetic properties of the product at this time is B ₁₀ = 1.93T, W17 _17/50 = a 0.62 W / kg, normal product plate is not performed EB irradiation through the same steps _{(B 10 = 1.93T, W 17} / ₅₀ = 0.92 W / kg), which is a significant improvement of 33%.

(Effects of the Invention) According to the present invention, it is possible to provide a unidirectionally formed silicon steel sheet in which iron loss is not deteriorated by strain relief annealing and a method for stably manufacturing the silicon steel sheet.

[Brief description of the drawings]

1 (a) and 1 (b) are schematic diagrams showing a mechanism for improving the magnetic properties of the present invention, and FIG. 2 is a schematic diagram showing the penetration force in the depth direction and the size in the width direction of a silicon steel sheet by various methods. FIG. FIGS. 3 to 5A are schematic diagrams showing EB irradiation traces, FIGS. 3 to 5B are schematic diagrams showing EB intensity, and FIGS. 3 to 5C are changes in EB scanning position and time. FIG. 1 ... forsterite undercoating 2 ... insulation coating 3 ... ground iron

Claims (6)

(57) [Claims] 1. A unidirectional silicon steel sheet with a forsterite coating which has been subjected to finish annealing, wherein a micro-press-fitted region in which the forsterite coating on the steel sheet surface is pressed into the ground iron is perpendicular to the rolling direction of the steel sheet. Low iron loss unidirectional silicon steel sheet locally introduced in the direction. 2. A small press-fit region in which a forsterite coating and an insulating coating on the surface of a steel plate are press-fitted into a base iron by forming a unidirectional silicon steel sheet having an insulating coating further formed on a forsterite coating subjected to finish annealing. , A low iron loss unidirectional silicon steel sheet locally introduced in a direction perpendicular to the rolling direction of the steel sheet. 3. The low iron loss unidirectional silicon steel sheet according to claim 1, wherein the minute press-fitting region is such that a press-fit portion on the surface of the steel sheet extends through the ground iron to a coating on the back surface of the steel sheet. 4. A unidirectional silicon steel sheet having undergone finish annealing,
On its surface, acceleration voltage: 100-500 kV and acceleration current: 0.
An electron beam generated at 005 to 10 mA is locally irradiated in a direction perpendicular to the rolling direction, and the coating on the steel sheet surface is pressed into ground iron to reduce the iron loss of the unidirectional silicon steel sheet. Production method. 5. A unidirectional silicon steel sheet having been subjected to finish annealing,
On its surface, acceleration voltage: 100-500 kV and acceleration current: 0.
Locally irradiate the electron beam generated at 005 to 10 mA in the direction perpendicular to the rolling direction, and press-fit the coating on the steel sheet surface to the base steel, and press-fit the base steel to the coating on the back surface of the steel sheet. A method for producing a low iron loss unidirectional silicon steel sheet, comprising: 6. The method according to claim 4, wherein the irradiation diameter and the irradiation interval of the electron beam are changed.