JPH03260022A - Method for radiating linear eb - Google Patents

Abstract

PURPOSE:To stably manufacture a low iron loss grain-oriented silicon steel plate without deteriorating the iron loss by radiating electron beam having high voltage and low current on the surface of the grain-oriented silicon steel plate after finish-annealing and repeatedly scanning the steel plate as crossing to the rolling direction and in the same direction. CONSTITUTION:In the grain-oriented silicon steel plate attaching forsterite quality film after finish-annealing or further, providing insulating film on this film, on the surface, the electron beam generated with high voltage and low current is locally radiated. Then the above electron beam scans in the direction crossing to the rolling direction of steel plate. Further, this scanning is repeatedly executed with the same direction to the rolling direction. By this method, the above film on the steel plate surface is pressed in the basis iron. Further, the iron loss is reduced by making magnetic domain fine and the low iron loss-unioriented silicon steel plate without deteriorating the iron loss with the stress relies annealing, is stably obtd.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a unidirectional silicon steel plate with low core loss, and in particular, subdivides magnetic domains by press-fitting a coating on the surface of the steel plate into a base steel. The aim is to reduce iron loss.

(Prior technology) Unidirectional silicon steel sheets have secondary recrystallized grains of the product highly concentrated in the Goss orientation, and a forsterite film is formed on the surface of the steel sheet, which has a small coefficient of thermal expansion. It has an exposed insulation coating and is complex and requires strict control.
It is manufactured through a wide variety of processes.

Such unidirectional silicon steel sheets are mainly used as iron cores for transformers and other electrical equipment, and their magnetic properties include high magnetic flux density (represented by the Boo value) and iron loss (W, 7. , (represented by .), and an insulating film with good surface properties.

Particularly in the wake of the energy crisis, demand for features such as reduced power loss has become significantly stronger, and the need for unidirectional silicon steel sheets with lower iron loss as core materials for transformers has become increasingly important.

Now, the history of iron loss improvement of unidirectional silicon steel sheets is based on Goss direction 2.
It is no exaggeration to say that this is a history of improvements in the secondary recrystallization texture. As a method for controlling such secondary recrystallized grains, a method has been implemented in which primary recrystallized grain growth inhibitors such as AIN, MnS, and MnSe are used to preferentially grow Goss-oriented secondary recrystallized grains. ing.

On the other hand, a completely different method is used to control the secondary recrystallization texture, namely laser irradiation on the steel sheet surface (center of gravity).
Correct: Tetsu to Hagane, 69 (1983), P, 895, Special Publication No. 57-2252, No. 57-53419, No. 58-2
4605, 58-24606) or plasma irradiation (JP-A-62-9661.7, JP-A-62-1
No. 51511, No. 62151516 and No. 62-1
No. 51517) proposed an innovative method of introducing local microstrain to subdivide magnetic domains and thereby reduce iron loss. However, when steel plates obtained by these methods are heated to a high temperature range, minute strains disappear, so
It has the disadvantage that it cannot be used as a material for wound core transformers that undergoes high-temperature strain relief annealing.

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. 1983-
35679, JP-A No. 59-28525 and JP-A-59-28525
197520), a method for forming finely recrystallized grain regions on the surface of a finish annealed plate (Japanese Patent Laid-Open No. 130454/1983)
JP-A-60-92479, JP-A-60-92480, JP-A-60-92481 and JP-A-60-60
-258479), a method of forming different compositional regions in the steel base, in the forsterite coating, or in the tension insulation coating (JP-A-60-103124 and JP-A-60-10).
3182), etc.

However, these methods have not been adopted industrially because the process is complicated, the effect of reducing iron loss is small, and the manufacturing cost is high.

(Problems to be Solved by the Invention) The present invention provides low core loss unidirectional silicon in which the core loss reduced by magnetic domain refining does not deteriorate even after strain relief annealing, and which can be stably manufactured. The purpose of this invention is to propose a steel plate and a method for advantageously manufacturing this steel plate.

(Means for Solving the Problems) The present invention provides a unidirectional silicon steel plate with a finish annealed forsterite coating or an insulating coating on the forsterite coating. When locally irradiating an electron beam generated with a small current, scanning of the electron beam in a direction crossing the rolling direction of the steel plate is repeated in the same direction in the rolling direction to form a coating on the surface of the steel plate. This is a method for producing a low core loss unidirectional silicon steel sheet, which is characterized by press-fitting the steel into a base steel.

The unidirectional silicon steel sheet that is the subject of this invention is also suitable for use with a forsterite coating on its surface, or with an insulating coating formed on the forsterite coating.

In order to press-fit the forsterite coating and the insulating coating deep into the steel base in the width direction of the steel plate in a minute area, it is only possible to use a high voltage and small current electron beam (hereinafter referred to as EB). . In other words, especially when using high voltage and small current EB, it has a stronger penetration power in the depth direction than other methods (laser plasma, mechanical methods, etc.), and also penetrates in the narrowest width. , it becomes possible to press the base film and the insulating film into the base metal without losing them.

Further, as the silicon-containing steel that is the material of this invention, any conventionally known compositions are suitable, but typical compositions are as follows.

C: 0.01 to 0.10% C is an element that is useful for the development of Goss orientation by uniformly refining the structure during hot rolling and cold rolling, and it is added at least 0.01% or more. is preferred. However, 0.1
If the content exceeds 0%, the Goss orientation will be disturbed, so the upper limit is preferably about 0.10%.

Si: 2.0 to 4.5% Si increases the specific resistance of the steel sheet and effectively contributes to reducing iron loss, but if it exceeds 4.5%, cold rollability is impaired;
If it is less than 0%, not only will the resistivity decrease, but also randomization of crystal orientation will occur due to α-γ transformation during the final high-temperature annealing performed for secondary recrystallization and purification, resulting in a sufficient iron loss improvement effect. is not obtained, the amount of Si is preferably about 2.0 to 4.5%.

Mn: 0.02-0.12% Mn is at least 0.02% to prevent hot embrittlement
It is preferable to set the upper limit at about 0.12%, since too much content deteriorates the magnetic properties.

Inhibitors include so-called MnS, MnSe, and AIN inhibitors. In the case of MnS and MnSe, at least one selected from Se and S: 0
．． 005 to 0.06% Se and S are both effective elements as inhibitors that control secondary recrystallization of grain-oriented silicon steel sheets. From the viewpoint of securing suppressive force, it is necessary to have at least about 0.005%, or if it exceeds 0.06%, the effect will be impaired, so the lower and upper limits are 0.01% and 0.01%, respectively.
It is preferable to set it to about 0.06%.

In the case of AIN type, Al: 0.005~0.10%, N: 0.004~
MnS as described above also for the 0.015% AI and N ranges.

The above range was set for the same reason as in the case of the MnSe system. MnS, MnSe and AI mentioned above
N series can be used in combination.

As inhibitor components, the above-mentioned S, Se, AI
In addition to Cu, Sn, Cr, Ge, Sb, Mo
, Te, Bi and P etc. are also advantageously suited, so
They can also be contained together in small amounts. Here, the preferred addition ranges of the above components are Cu, Sn, and C.
r: 0.01-0.15%, Ge, Sb, Mo
, Te, Bi: 0.005-0.1%, P: 0
．． 01 to 0.2%, and each of these inhibitor components can be used alone or in combination.

(for production) Next, this invention will be described in detail based on experimental examples.

C: 0.048 wt% (hereinafter simply referred to as %), s
i: 3.42%, Mn: 0.072%, S
e: 0.021%, Sb: 0°027%.

A silicon steel slab containing Mo: 01012% and the remainder substantially Fe was heated at 1390°C for 4 hours, hot rolled into a 2.4mm thick hot rolled sheet, and then rolled at 1000°C for 3 hours.
Cold rolled twice with intermediate annealing for 0.20 min.
A final cold-rolled sheet having a thickness of mrn was obtained. Then, after decarburizing primary recrystallization annealing in wet hydrogen at 825°C, M
After applying a slurry of an annealing separator mainly composed of gO, secondary recrystallization annealing was performed at 850°C for 50 hours to preferentially grow Goss-oriented secondary recrystallized grains, and then soft hydrogen was applied at 1200°C. Purification annealing was performed for 5 hours in the inside. Next, after forming an insulating film mainly composed of phosphate and colloidal silica on the surface of the steel sheet, an EB of 0.12 mmφ generated at 150 kV and 1.3 mA was applied in the rolling direction according to the following conditions The irradiation was performed by scanning in the direction perpendicular to the rolling direction, and this irradiation was repeated at intervals of 5 mm in the rolling direction, and then 8
Strain relief annealing was performed at 00°C for 3 hours. For comparison, a similar experiment was also conducted without EB pre-irradiation.

Note: Scanning speed: 6 m/min, scanning direction: both directions (see Figure 2), dot-shaped irradiation interval of 300 μm (Figure 3 (a+
(Reference) ■Scanning speed: 6m/min, one scanning direction (first
(see figure), dot-shaped irradiation, spacing 300 μm (see figure 3 (a)
)) ■Scanning speed: 6m/min, scanning direction: both directions (second
(see figure), linear irradiation (see figure 3(b)) ■Scanning speed:
6m/min, scanning direction in both directions (see Figure 1),
Linear irradiation (see Figure 3(b)) ■Scanning speed: 6m, /
min, one direction in the scanning direction (see Fig. 2), zigzag irradiation: X-direction interval 300 μm.

Y-direction spacing: 300 μm (see Figure 3 (C)) ■Scanning speed: 6 m/min, in both scanning directions (see Figure 1),
Zigzag irradiation: X-direction interval 300 μm.

)・' direction spacing 300 μm (see FIG. 3(C)) In FIGS. 1 and 2, the symbol 1 indicates the scanning line of EB, and the arrow 2 indicates the advancing (rolling) direction of the steel plate.

The magnetic properties of the steel sheet thus obtained after strain relief annealing are shown in Table 1.

As is clear from Table 1 and the same table, steel sheets that are not irradiated with EB have iron loss WI? 150 is significantly improved to 0.05 to 0.12 W/kg. This is because the forsterite coating and insulating coating on the surface of the steel sheet are press-fitted into the base steel (secondary recrystallized grains with Goss orientation) in the depth direction in a minute region, resulting in effective magnetic domains even after strain relief annealing. This is because it acts as a subdivision nucleus, making it possible to subdivide magnetic domains.

It can also be seen that the improvement in iron loss varies depending on the EB irradiation conditions.

In other words, steel plates subjected to bidirectional scanning under irradiation conditions (■, ■, and ■) have a reduction in iron loss of 0.04 to 0.05 W/'kg compared to steel plates subjected to unidirectional scanning under irradiation conditions (■, ■, and ■). To a lesser extent.

When the EB is scanned in both directions, it is technically difficult to maintain the scanning direction perpendicular to the advancing (rolling) direction of the steel plate, as shown in FIG.

This is because it is extremely difficult to achieve a direction completely perpendicular to the direction in which the steel plate travels, and a trapezoidal scanning pattern is usually obtained.

In particular, when irradiating both sides of a steel plate, there is a deviation in the angle of the EB scanning line with respect to the steel plate traveling direction on the front and back sides, so it is thought that the magnetic domains are not sufficiently subdivided and the improvement in iron loss is small. .

On the other hand, when the EB is scanned in one direction as shown in Fig. 1, it is possible to maintain the scanning direction perpendicular to the rolling (advancement) direction of the steel plate, and subdivide the magnetic domain. The conversion is done sufficiently. Note that the unidirectional scanning of the EB is achieved by returning to the scanning starting point once after scanning and scanning in the same direction again, and by performing the scanning at ultra high speed when returning to the scanning starting point, adverse effects on iron loss can be avoided.

Note that the penetrating power of EB in the thickness direction (depth direction) of a silicon steel plate increases at an accelerating voltage of 65 kV or higher, where a large amount of X-rays are normally generated. It is important to set the accelerating current to a high value (65 to 500 kV) and a small accelerating current (0,001 to 5 mA), thereby increasing the penetrating power in the thickness direction of the silicon steel plate. Furthermore, in order to efficiently perform magnetic domain refining, the irradiation area is reduced to 0.5 by using a small diameter EB.
It is preferable to make the size smaller than mmφ. Furthermore, after this pre-EB irradiation, an insulating film may be applied on top of it to further strengthen the insulation over the EB irradiation traces, but this increases the cost, so normally the insulating effect is sufficient even if it is not applied. can.

Furthermore, the steel plate according to the present invention can be used for stacked iron cores and wound cores, but when used for stacked iron cores, a guide with a minute press-fit area that is thinner than that for rolled iron cores is required, so EB
It is preferable that the irradiation conditions be such that the current is small and the scanning interval is wide. -The EB irradiation conditions when applying to 10,000-volume iron core material are as follows:
In order to avoid deterioration of characteristics even when strain relief annealing is performed, it is preferable to increase the current slightly and narrow the scanning interval to promote the introduction of minute press-fit regions on the surface of the steel sheet.

Note that EB unidirectional scanning is particularly effective when scanning regularly at equal intervals in the advancing (rolling) direction of the steel plate. This method not only improves magnetic properties but also improves the local It is also advantageously suitable for heat treatment and the like.

(Example) Example 1 (A) C: 0.072%, Si: 3.36%, Al
: 0.026%, S: 0.028%, Cu: 0
．． 98%, Sn: 0.08% or (B) C: 0
．． 045%, Si: 3.39%, Mn: 0.063
%, Se: 0.021%, Sb: 0.029%
, Mo: 0.012% respectively, with the remainder substantially consisting of Fe. A finish annealed plate (0.20 mm thick) with a forsterite coating was subjected to EB in a direction perpendicular to the rolling direction using an EB device. EB irradiation was performed by scanning from one direction. The EB irradiation conditions are acceleration voltage: 150kV,
Accelerating current: 1.3 mA, beam diameter: 0.15 mm, beam spot center spacing: 300 μm, and scanning interval:
5 mm, and EB irradiation was applied to both sides of the steel plate.

When the treated product was subjected to strain relief annealing at 800° C. for 2 hours, its magnetic properties were as shown below.

(A) B+o=1.95T, W+7. zso=0
．． 77W/kg(B) BIO=1.92T, W+7
150 = 0.78 W/kg (Effects of the Invention) According to the present invention, it is possible to stably manufacture a grain-oriented silicon steel sheet whose core loss does not deteriorate even after strain relief annealing.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the EB scanning procedure according to the present invention;

Claims (1)

[Claims] 1. When locally irradiating the surface of a unidirectional silicon steel plate with a forsterite film that has undergone final annealing with an electron beam generated at a high voltage and a small current, Low iron loss unidirectional silicon characterized by scanning an electron beam in a direction intersecting the rolling direction of a steel plate and repeating the scanning in the same direction in the rolling direction to press-fit the coating on the surface of the steel plate into the base steel. Method of manufacturing steel plates. 2. When locally irradiating the surface of a unidirectional silicon steel plate, which has an insulating coating on top of the forsterite coating that has undergone final annealing, with an electron beam generated at high voltage and low current, the steel plate A low iron loss unidirectional silicon steel plate characterized in that the coating on the surface of the steel plate is press-fitted into the base steel by repeatedly scanning an electron beam in the direction crossing the rolling direction with the same scanning direction in the rolling direction. manufacturing method.