JPS59197520A - Manufacture of single-oriented electromagnetic steel sheet having low iron loss - Google Patents

Abstract

PURPOSE:To obtain a single-oriented electromagnetic steel sheet of which iron loss is not determined even though high temperature stress-relieving annealing is processed, by inducting seams onto the steel sheet before the final finish annealing process of silicon steel hot-rolled sheet limiting Si content. CONSTITUTION:The silicon steel hot-rolled sheet containing 4.5wt% max. Si is cold-rolled to final product sheet thickness putting intermediate annealing between the cold rollings and final finish annealing is processed after decarborizing annealing. Seams are inducted onto the steel sheet before this final finish annealing process. If possible, those seams should be 300mum max. in width, about 1.0mum max. in length and about 1mm. in the gap of rolling direction in the direction almost at right angle to rolling direction, and they are given by means of the edge of knife, laser beam etc. By this method, the iron loss improved for annealing at a high temperature can be maintained and the single-oriented electromagnetic steel sheet having iron loss suitable for iron core material can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field Unidirectional electrical steel sheets are mainly used as cores for transformers and other electrical equipment, and are required to have good magnetic properties. In particular, it is important that the energy loss, ie, iron loss, be low when used as an iron core, and as the energy situation has worsened in recent years, the demand for electrical steel sheets with particularly low iron loss has become even higher.

Conventional technology and its problems By the way, in order to completely reduce the iron loss, the crystal orientation must be changed to (11
Various attempts have been made to align the 0)(001) orientation to a higher degree, to increase the S1 content, thereby increasing the electrical resistance of the steel sheet, and to reduce impurities. However, reduction of iron loss by these methods has almost reached its limit due to recent technological improvements.

Japanese Patent Application Laid-Open No. 50-187819 proposes a method for reducing the secondary grain size and iron loss by forming a secondary recrystallization inhibiting region in a steel plate. This method is difficult to put into practical use and is not actually used.

In this way, the reduction of iron loss by metallurgical methods has almost reached its limit, and W1715o has reached a limit of 1. ooW, it was impossible to manufacture a steel plate of 4° or less. Here W1
715o is the iron loss at a magnetic flux density of 1.7 T and a frequency of 50 Hz.

Therefore, in order to achieve a dramatic reduction in iron loss, it is necessary to use methods other than metallurgical means.

One such method is to make the surface of the steel plate mirror-like, as proposed in Japanese Patent Application Laid-Open No. 49-96920, but it has not been put to practical use due to problems such as insulation of the steel plate. .

There have also been attempts to completely reduce iron loss by introducing linear flaws into finished annealed steel sheets with the edge of a knife or razor, but this method does not allow for the deterioration of the insulation coating due to the flaws and the burrs that form around the flaws. There are problems such as deterioration of space factor and deterioration of magnetostriction.In particular, when steel plates are laminated, the iron loss characteristics of a single plate cannot be utilized as is.
Has a point. Therefore, transformers and wound cores that are used in a stacked manner have no practical advantage and are not actually used.

As yet another method, JP-A No. 117016,
JP-A-55-18566 and JP-A-57-1888
No. 10 and other publications propose methods for improving iron loss characteristics by creating micro-strains in steel sheets after finish annealing.
Sue by laser! Although the methods are different, latching and electrical discharge machining, both have the same basic concept: to subdivide the magnetic domain by introducing the above-mentioned minute strain after final annealing, and to reduce iron loss. .

However, these methods require subsequent annealing at high temperatures.
The disadvantage is that the iron loss deteriorates when the
However, it cannot be used as a material for wound cores that require strain-removal annealing at high temperatures.

Purpose of the Invention The present invention provides a low iron loss unidirectional electrical steel sheet which does not have the above-mentioned drawbacks and does not suffer from deterioration of iron loss even when strain relief annealing is performed at high temperatures. The purpose is to manufacture.

The constitution of the invention, that is, this invention is based on Si, 4.5% by weight (hereinafter simply referred to as %).
Hot-rolled silicon steel sheet 'f' containing the following: The final product thickness is obtained by cold rolling once or twice or more with intermediate annealing, and after decarburization annealing, final finish annealing is performed. This is a method for producing unidirectional electrical steel sheets with low core loss, which involves introducing linear flaws into the steel sheet before the final finishing annealing process. It is practically preferable that the linear flaws introduced into the steel sheet before the annealing step have a width of 800 μm or less, a depth of 100 μm or less, and an interval of 1 mm or more in the rolling direction in a direction substantially perpendicular to the rolling direction of the steel sheet. It is a mode.

The above configuration will be explained in detail below.

Unidirectional electrical steel sheets are made by cold rolling silicon steel hot-rolled sheets containing Si 4.5% or less once or twice or more with intermediate annealing to achieve the final product thickness - decarburization annealing. After that, it is usually manufactured by performing a final finish annealing.

Final annealing is performed by coating a steel plate with an annealing separator mainly consisting of MgO, coiling it, and performing it in a hydrogen atmosphere at approximately 1200°C. Purification of impurities takes place.

After final annealing, unreacted MgO is removed from the steel sheet, and an insulating coating such as phosphate is applied thereon. In this coating treatment, the steel plate is heated to about 800° C., and the coil set during final annealing is removed at the same time.

As a result of extensive research regarding final finish annealing, the inventors found through the experiment shown below that iron loss is significantly reduced, especially when finish annealing is performed with linear flaws introduced into the steel sheet. For the 0 experiment, OO,045%,
Si 8.8%, Mn 0.07%.

Also, as inhibitor j-, se U, 02%, 'Sb
A continuous cast slab containing @0 and 025% is hot rolled to produce a unidirectional electrical steel sheet material, and the final thickness is obtained by cold rolling twice.

A cold rolled sample was used. For those samples, after final cold rolling (A), after final cold rolling and decarburization annealing (B), and further after final cold rolling and decarburization annealing.
After finishing annealing through 0 (0), each width is 100μ
Linear flaws with a depth of 20μ were introduced at 5 mm intervals in a direction almost perpendicular to the rolling direction, and each test steel sheet was further subjected to decarburization annealing, finishing annealing, insulation coating treatment, and finishing in the above order. Products were made by performing annealing, insulation coating treatment, and insulation coating treatment only. Table 1 shows the iron loss and the magnetic properties of these magnetic properties compared with that of CD (CD), which uses a similar process without introducing flaws.
The value of magnetic flux density is listed.

Table 1 The magnetic properties are based on the results (SST measurement values) using a veneer tester using a specimen of width 150 mm and length 280 mm, and
Samples with a width of 3Qmlfr and a length of 280mm were heated at 800℃ x 3
The values measured by an Epstein tester (JI302550) after time-strain annealing are compared. From the same table, for samples (A) and CB), both SST measurement and Epstein measurement were tested (C).

It can be seen that the iron loss is significantly improved as compared to CD) by at least 0.04 to 0-094.

The reason for this decrease in iron loss is not clear, but it is thought to be because the presence of linear flaws in the steel sheet during final annealing allows atmospheric gas to penetrate well into the interlayers of the steel sheet, promoting purification of impurities.

Next, the width and depth of the linear flaws introduced into the sample (A) before decarburization annealing at intervals of 5 squares in a direction approximately perpendicular to the rolling direction of the steel plate affect the low iron loss range of the product. Figure 1 shows the results of an investigation of wisdom.

The iron loss reduction height, which is distinguished by marks e, ■, ■, ■ and Depth of flaw 100μ
Hereinafter, it is clear that there is a remarkable improvement in the reduction in iron loss within the width range of 300 μm or less.

Similarly, for the sample (A), Fig. 2 shows the full effect of the interval at which linear flaws are introduced on the iron loss reduction height, 1 myth
If the introduction interval is narrower, the iron loss may actually deteriorate, so it is desirable that the interval be 1 rnm or more, particularly about 5 nm.

Methods for introducing linear flaws include the edge of a knife, laser beam, electric discharge machining, electron beam, etc., but there is no particular limitation, and the point is that any method that can introduce linear flaws in a desired shape is sufficient. It is.

Furthermore, Figure 8 similarly shows the relationship between the introduction direction of linear flaws and the iron loss reduction height for sample (A), and the iron loss reduction effect was determined when the introduction direction of linear flaws was perpendicular to the rolling direction. It is largest in the rolling direction, and becomes smaller as it gets closer to the rolling direction. Therefore, it is preferable that the direction in which linear flaws are introduced is approximately perpendicular to the rolling direction.1. .

Delicious.

Further, the flaw needs to be linear, and the linear shape may be a straight line, a wavy line, a broken line, or a dotted line.

The feature of this invention is that linear flaws are introduced into the steel plate before the final finishing annealing process.

Regarding the timing of introducing defects, it is sufficient to introduce them before the final finish annealing process, and it is important that the introduced defects remain during the final finish annealing, taking into account the manufacturing process of grain-oriented electrical steel sheets. If so, the final product.

It is desirable to introduce it after the cold rolling process to adjust the plate thickness and before the final finishing annealing process.

That is, since it is sufficient that the flaws remain at the time of the final finish annealing, it is not necessarily necessary to introduce the flaws after the final cold rolling, and it is also possible to introduce the flaws before the final cold rolling. However, in this case, it is necessary to set the rolling reduction rate in the final cold rolling to a level that does not eliminate defects.

Further, even if an insulating coating such as a phosphate coating is applied to the final annealed steel sheet after the introduction of defects, the effects of the present invention will not be lost.

In the above-mentioned Japanese Patent Application Laid-Open No. 50-187819, a secondary recrystallization inhibiting region is introduced by applying plastic strain to a steel sheet before final annealing in a range of 0.5 to 3 widths, thereby controlling the crystal grain size. On the contrary, in the introduction of the above-mentioned linear flaws in this invention, the position of the flaws and the grain boundaries are unrelated, and the sample ( Regarding A), as shown in Fig. 4 (a) and (b), the total metal structure with and without linear flaws is shown in Figure 3, linear flaws do not have the function of inhibiting secondary recrystallization, and the crystal grain size is It does not contribute to control, etc.

As described above, in this invention, the improvement in iron loss by introducing linear flaws before the final finish annealing process is sustained even after high-temperature strain relief annealing, and there is no effect on the iron loss value. There is no change. Therefore, it has the great advantage that it can also be used as a material for wound cores.

Example 1 00.043%, Si 8.3%, 'bin 0.
068%, SeO as inhibitor, 018%, S
b A unidirectional electrical steel sheet material hot-rolled from a continuous casting slab containing 24% O, was cold-rolled twice to a final thickness of o.
, aomm cold-rolled steel sheet, 51 mm in a direction almost perpendicular to the rolling direction while changing the pulse laser irradiation conditions.
Linear flaws with widths and depths shown in Table 2 were introduced at the spacing between the edges. After degreasing each of these steel plates (E,) to (H), decarburization annealing, which also serves as primary recrystallization annealing at 820°C in a wet hydrogen atmosphere, was performed at 1180°C for 5 hours in a hydrogen atmosphere. Table 2 shows the iron loss and magnetic flux of the cooling characteristics of the finished product after high-temperature annealing and insulating coating treatment, compared with the case (I) that went through the same process without introducing flaws. The density value was listed.

Table 2 Note: (1) is 0.02 to 0-0 due to the introduction of linear flaws as shown in the comparison table.
09 W4g iron loss reduction effect was obtained.

Example 2 Next, a cold-rolled steel sheet having the same composition and manufacturing history as Example 1 was mechanically cut to a width of 8" with a knife in a direction perpendicular to the rolling direction.
Linear flaws of 5μ and depth of 20μ were introduced at 5mm intervals.

After degreasing this steel plate, it was heated to 820°C in a wet hydrogen atmosphere.
After decarburization annealing, which also serves as primary recrystallization annealing, a final high temperature annealing of 1180'QX for 5 hours was performed in a hydrogen atmosphere. As a result, a unidirectional electrical steel sheet with the following properties was obtained. Ta.

W 1'7/i, o= 0.98 w, 4. B1o
= 1.91'l" (SST value) W 17/.-0
,93% B□. = 1.91T (Epstein f straight 9 At this time, the magnetic t+?f property of the comparative material without introducing any defects is W 1715o-1,03W4 B 1.o-1
, 92T CSST value] W1 phi. = 1.04 brother 4
g B. = 1.92T (there is an Epstein value,
By introducing linear flaws, an iron loss reduction effect of approximately 0.10 W4 was obtained.

Example 3 A cold-rolled steel sheet having the same composition and manufacturing history as Example 1 was similarly degreased and then heated at 820°C in a wet hydrogen atmosphere.
Decarburization annealing was performed, which also serves as primary recrystallization annealing.

By subjecting this steel plate to hot working, linear flaws of 180 μm and 15 μm in depth were introduced at 5 mm intervals in a direction perpendicular to the rolling direction. After that, it was heated at 1180℃× in a hydrogen atmosphere.
As a result of finishing high temperature annealing for 5 hours, a unidirectional electrical steel sheet having the following properties was obtained.

W 1?10=0.96 W/jgB□. =1.90
T (SST value) W 17zgo= 0-95 VJ/
fcgB□o=1. ．． 91 T (Epstein value) At this time, the magnetic properties of the comparison material without introducing any defects are Wl phi.

-E-04, W/icy B□. -1,91T (SS
T value) W 1?10=1.0.3”/# B,.=1
．． 91T (Epstein value), and an iron loss reduction effect of 0.08 WAg was obtained by introducing linear flaws.

Effects of the Invention As described above, this invention advantageously achieves a significant improvement in iron loss and low wave height without requiring any significant changes in the manufacturing process of grain-oriented electrical steel sheets.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the shape of the flaw introduced in this invention and the iron loss low wave height, Figure 2 is a graph showing the relationship between the introduction interval of linear flaws and the iron loss low wave height, and Figure 3 is the line 4 is a graph showing the relationship between the introduction direction of flaws and the iron loss low wave height, and FIGS. 4(a) and 4(b) show that the linear flaw force ≦ introduced by the present invention is different from the case where no linear flaws are introduced. Secondary reunion 1...
This is a photograph of the structure showing that it does not affect the product. Patent applicant: Kawasaki Steel Corporation ΔW% Tsumupuji 010~0005~θ, θ9 00.03~0θ4 ■0. Ol~θθ2 Takajihime-width (/l) Fig. 2 臘4 is covered with a shield m)

Claims (1)

[Claims] 1 silicon steel hot-rolled plate containing 4.5% by weight or less of L Si.
In the manufacturing method of grain-oriented electrical steel sheets, the final product thickness is obtained by cold rolling two or more times with intermediate annealing, and final finish annealing is performed after decarburization annealing. A method for producing a unidirectional electrical steel sheet with low core loss, characterized by fully introducing linear defects into the steel sheet before a finishing firing process. a Before the final finishing annealing process, the width is 800μ or less and the depth is 100μ or less in a direction almost perpendicular to the rolling direction of the steel plate.
1. The method according to 1, which comprises introducing linear flaws having a spacing of IIπm or more in the rolling direction.