JPS6046319A - Preparation of one directional silicon steel plate - Google Patents

Abstract

PURPOSE:To impart excellent magnetic characteristics, in applying intermediate annealing to a silicon steel slab containing a specific amount of C, Si, Mn and one or more of S and Se before final cold rolling, by imparting an AC magnetic field with a specific value or more in the recrystallization initial stage thereof. CONSTITUTION:On a wt% basis, 0.025-0.1 C, 2.5-4 Si, 0.02-0.15 Mn and 0.003-0.08 one or more of S and Se are contained in a silicon steel slab. This steel slab is hot rolled and two times of cold rollings interposing intermediate annealing at 750-1,100 deg.C are applied to the hot rolled plate and a draft in the final cold rolling among two times of cold rollings is set to 40-80% to obtain a predetermined plate thickness. This cold rolled plate is subjected to decarburizing annealing and final annealing to obtain a one directional silicon steel plate. In performing intermediate annealing before final cold rolling, an AC magnetic field with 100 oersted or more is applied to the steel plate in parallel to the rolling direction thereof at the initial stage of recrystallization.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a unidirectional silicon steel sheet having excellent magnetic properties and having a <100> axis, which is an axis of easy magnetization, in the rolling direction.

As is well known, unidirectional silicon steel sheets are mainly used for the iron cores of transformers and other electrical equipment, and due to the strong demand for energy and resource conservation in recent years, they are being used to reduce power loss in electrical equipment such as transformers. As more emphasis has been placed on efficiency, the unidirectional silicon steel plate used as the iron core material is also required to have even better magnetic properties. As for the magnetic properties of such a unidirectional silicon disk, the magnetic flux density Blo value (magnetic flux density in the rolling direction generated when the magnetic field strength is 100 OA/m) is 1,857 (Tesla) as the excitation property. ．． Above, W17150 value (
1.20W/kg at AC 50Hz, magnetic flux density 1.7T (te (7) iron loss value). In particular, iron loss characteristics have been significantly improved in recent years, and excellent products with a W 17750 value of 1.10 W /kQ or less have been realized.

In order to manufacture unidirectional silicon steel sheets with such excellent magnetic properties, secondary recrystallization is completely developed in the final annealing of the series of manufacturing steps, so that the so-called Goss orientation ( 110) It is necessary to have an aggregated FA weave in which the secondary recrystallized grains in the [001] orientation are sharply aligned. To achieve this, as is well known, the secondary recrystallization process (110)[0
The presence of an inhibitor to strongly suppress the growth of primary recrystallized grains having unfavorable orientations other than the [01] orientation is essential. As such inhibitors, fine precipitates such as L(n S , )Jn S e or △QN are usually used, and by adjusting the fine precipitates of these inhibitors mainly in the hot rolling process, Efforts have been made to exert a strong primary recrystallized grain growth suppressing effect. Recently, in addition to the above-mentioned J: Una fine precipitates, grain boundary segregation type elements such as 86, Bi, Sn, Pb,
A method of reinforcing the effect of suppressing crystal grain growth by adding Te or the like has also been adopted, and the role of an inhibitor has been brought to full play.

In addition, in order to sharply develop secondary recrystallized grains with the (110)[001] orientation, it is necessary not only to have the inhibitor as described above, but also to
] It is essential to form an appropriate primary recrystallized texture so that secondary recrystallized grains in the orientation can preferentially nucleate and grow.

Such an appropriate primary recrystallization texture can only be obtained by appropriately combining each process condition from the hot rolling process to the cold rolling process during the complex manufacturing process of unidirectional silicon steel sheets. Therefore, it is particularly important to select the final cold rolling reduction according to the magnitude of the suppressing effect of the inhibitor. For example, kins as an inhibitor, ),! When using nse, the most I? 'i The appropriate cold rolling reduction is within the range of 40 to 80%, and the primary recrystallization texture at this time is (11
It is known that the optimal state is such that the 0)[001] orientation is strongly concentrated and the weak (111)<112> orientation is distributed as sub-directions. However, the process conditions other than the final cold rolling reduction necessary for the formation of an appropriate primary recrystallization texture as mentioned above have not yet been fully established, and therefore there is still room for improvement. The reality is that there was.

Therefore, an object of the present invention is to improve process conditions in order to obtain a primary recrystallization texture that is even more suitable than before, and to stably produce a unidirectional silicon silver plate that has better magnetic properties than before. The purpose is to provide an efficient and economical method for industrial production.

In order to achieve the above-mentioned object, the present inventor has conducted various studies focusing on the intermediate annealing step before the final cold rolling in the two cold rolling steps, and found that the initial stage of the heating process in the intermediate annealing, That is, by applying an alternating magnetic field at the initial stage of recrystallization of the copper plate, (110)[001]
It has been shown that an optimal primary recrystallization assembly suitable for nucleating and developing oriented secondary recrystallized grains can be obtained, and as a result, a unidirectional silicon steel sheet with excellent magnetic properties can be obtained. This discovery led to this invention.

That is, the gist of this invention is basically that CO,025~
0.10%, 3i 2.5-4.0%, MnO,02
A process of hot rolling a silicon steel slab containing ~0.15% and one or both of S and Se in a total amount of 0.008 to 0.080%; On the other hand, cold rolling is performed twice with intermediate annealing at a temperature range of 750 to 1100°C, and the reduction rate in the final cold rolling of the two cold rolling is set to 40 to 80%. In a method for producing a grain-oriented silicon steel sheet, the method comprises a step of finishing the sheet to a predetermined thickness, and a step of applying decarburization annealing and R-holly annealing to the cold-rolled sheet.

Intermediate annealing before the final cold rolling (1) Applying an alternating current magnetic field of 100 oersted (Oe) or more in parallel to the rolling direction of the steel sheet within a temperature range of 500 ° C. or more and below the magnetic transformation point in the initial stage of recrystallization in the culm. This is a characteristic feature.

The method of this invention will be explained in detail below.

First, the reasons for limiting the composition of the silicon steel slab material used in the method of the present invention will be explained.

C is a necessary component in order to split and destroy crystal grains that have grown coarsely during high temperature heating of the material slab in the S rolling process by forming γ phase of a predetermined number or more in a specific temperature range during hot rolling, If it is less than 0.025%, the required m gamma phase cannot be ensured, and if it exceeds 0.10%, decarburization before final annealing becomes extremely difficult, requiring long decarburization annealing, which is not economical. Therefore, 0.025 h - 0,10
It is necessary to limit it within the range of %.

Si is an element necessary to increase resistivity and reduce iron loss. If it is less than 2.5%, it will not be possible to obtain a sufficiently low iron loss, while if it exceeds 4.0%, it will become extremely brittle and difficult to cool. The Si content must be within the range of 2.5% to 4.0% because the workability becomes poor and industrial rolling becomes difficult.

) Jn, S, and Se all serve as inhibitors to suppress the growth of unfavorable primary recrystallized grains other than the (110) [001] orientation in the secondary recrystallization process, and (110
) It is a necessary component to sufficiently develop secondary recrystallized grains with the [001] orientation, and if it is outside the above range, a sufficient inhibitor effect will not be obtained, so MnO,
02 to 0.15%, and s and se need to be in the range of 0.008 to 0.080% either alone or in combination.

In addition to the above-mentioned essential components, grain boundary segregation type elements such as 3b, As,
Adding Bi, pb, Te, 14a, W, etc. alone or in combination to the above material is not supported. however,
Even if these grain boundary segregation type elements are added, if the appropriate final cold rolling reduction exceeds 80%, the effect of improving the primary recrystallization aggregate structure of this invention disappears, so unnecessary addition is unnecessary. should be avoided.

Next, the material with the above-mentioned components is rolled, heated!
2! The conditions for each single culm in this invention will be explained.

First, for slabs that meet the above component conditions, 1250
After heating at a high temperature of about C or higher, a hot rolled sheet with a thickness of 1.5 to 5.0 mm is obtained by performing known hot rolling.In this hot rolling process, in order to obtain fine precipitates of inhibitors MI+S and Vase. , the slab high temperature heating temperature is) Jn, S, Se
The content of these components should be appropriately set so that they can be sufficiently dissociated into solid solution, and then it is important to appropriately select the hot rolling method to sufficiently promote fine precipitation of the inhibitor.

The hot-rolled sheet is subjected to normalizing annealing if necessary, and after pickling, cold rolling is performed twice with intermediate annealing in between to achieve the final thickness. Intermediate annealing is performed for the purpose of recrystallizing the cold-rolled structure after the first cold rolling, promoting uniformity of the crystal structure, and at the same time, sufficiently dissolving C into the steel. Therefore, the intermediate annealing temperature needs to be 750°C or higher, but if it exceeds 1100°C, the fine precipitates of the inhibitors (JnS and MnSe) will become coarse and the suppressing effect will decrease.
temperature range.

In the method of the present invention, in the intermediate annealing step as described above, an alternating current magnetic field of 100 oe or more is applied within a temperature range of 500'C or more and below the magnetic transformation point during the initial stage of recrystallization of the steel sheet during the temperature rise of the intermediate annealing. The basic feature is that it is applied parallel to the rolling direction of the steel sheet, thereby improving the recrystallization texture. These conditions were newly discovered through detailed experiments conducted exclusively by the present inventors, and these conditions will be explained below based on the experimental data of the present inventors.

Figure 1 shows that in the intermediate annealing step before the final cold rolling, an alternating current magnetic field of 100 oe [over 500°C and below the magnetic transformation point; case(
(method of the present invention), and in the case of using a knob without imparting 72 current magnetic j1 according to the conventional process, the recrystallization rate and (1'i 0 > plane, (220) plane X-ray We received the results of examining the diffraction intensity.

As is clear from the first part, when applying an alternating magnetic field and using conventional methods, A) re-occupation at the end of the day.7)' +)
'] In contrast, in the method of the present invention in which an alternating current filter is added, recrystallization starts at 600'C, which is approximately 100°C lower than in the conventional case of two people. With the start of C recrystallization, there was a clear tendency for the (!10) plane X-rays (Sefuyu to 6) and the (222) plane X-rays to become weaker. 2. After C recrystallization (1'
io) The surface x polar density is much higher in the case of the Kikomei method than in the conventional method, and it is clear that the recrystallization texture is improved. That is, in the initial stage of recrystallization formation, it is generally said that (1'l O)-oriented Goss iη is generated on the low temperature side, but in the method of the present invention, recrystallization nuclei are generated on the lower temperature side and Goss grains are Promote the generation of
It is possible to improve the recrystallization texture to a further strengthened Goss orientation integration degree before the final cold rolling.

As described above, the present inventors applied an alternating magnetic field during the intermediate annealing before the final cold rolling in the initial stage of the heating process to induce recrystallization at a lower temperature and to sharpen the Goss orientation. It was newly discovered that by accelerating the recrystallization, the recrystallization texture can be improved, and a product with excellent magnetic properties, which is the object of the present invention, can finally be obtained.

Here, in this invention, intermediate annealing! The reason why the temperature range for applying 1#A was limited to 500° C. or higher and lower than the magnetic transformation point at the initial stage of recrystallization is as follows.

In other words, if the recrystallization behavior during the temperature increase during continuous annealing is observed using a transparent microscope or an optical microscope, recrystallization nucleation is induced when the plate temperature reaches around 550°C.
Recrystallization begins at around 650°C and then completes at around 750°C. Applying a magnetic field in a temperature range below 500°C has no effect on recrystallization at all; on the other hand, the magnetic transformation point of the 9i 2.5% to 4.0% lock, which is the subject of this invention, is the moisture content at which recrystallization is completed. Since lB54 has no effect on the steel plate at temperatures close to 730-750° C. and above the magnetic transformation point, the alternating current r7A field was applied at temperatures above 500”C and below the magnetic transformation point.

It is most desirable to apply the AC magnetic field over the entire temperature range from 500'C to the magnetic transformation point, but it is not necessarily necessary to apply the magnetic field over the entire temperature range (for example, from 550'C to the temperature range mentioned above). A magnetic field may be applied in a range up to 700°C, or in a range from 500″C to 650°C, and even in that case, a corresponding effect can be obtained.However, among the above temperature ranges,
It is desirable to apply a magnetic field at least in the range of 550 to 650°C.

In addition, Kikyuichi et al. carried out the following in order to investigate why applying an alternating GTL'A field during the heating process of intermediate annealing before final cold rolling is effective in improving and stabilizing magnetic properties. We conducted an experiment.

The materials used in the experiment were 9i 2.8-3.1% and S
i 3.3-3.5% The Si content of the second group, and the corresponding C amount is in the range corresponding to γ layer formation j in the equilibrium state of 1150 ° C. 10-30%, and roughly Mn
O,06%, 3 e O,025%, Smu 0,02
5%, and finished through normal steelmaking, continuous casting, and hot rolling processes with a thickness of 3. It is a hot-rolled sheet of Omm. After annealing such a hot-rolled plate at 950°C for 1 minute, it was pickled and cold-rolled for the first time to give an intermediate plate thickness of 0.75m5, and then rolled at 950°C for 2 minutes.
After intermediate annealing for 1 minute, final cold rolling was performed at a reduction rate of 60% to give a final plate thickness of 0.30 mm. Next, decarburization annealing was performed for 5 minutes in wet hydrogen at 800°C, and after applying MgO as an annealing separation material, the secondary recrystallized structure was sufficiently maintained at 860°C for 30 hours during the temperature raising process as final annealing. Treatment for development and further heating at 1200℃ for 10
This was combined with a purification treatment to remove impurities in the steel over a period of time, and a unidirectional silicon steel sheet product was finally obtained. During this process, the initial stage of recrystallization during the temperature increase process of intermediate annealing
V! in the temperature range of 00℃ or higher and lower than the magnetic transformation point! AC IB was applied parallel to the rolling direction of the copper plate by varying the strength of the i-field from 0 to 1000 oe or more. The relationship between the strength of the alternating magnetic field and the final strength of the product, ≦1 - that is, the B10 value and the iron loss W17/50, is shown in Figure 2.

As shown in FIG. 2, 9i 2.8-3.
1% details and black circles indicate Si 3.2-3.596
As a result of conducting experiments using a large number of test samples, it was found that even with the Si-containing sample of the same name, the strength of the play field was 100 apl or more, and the strength of the material 11 was even higher. 2ζ
It was found that when the magnetic field is 100 oc or less, 1) 1) the alternating current magnetic field has almost no effect on improving the magnetic properties of the product; Therefore, in this sense, the strength of the alternating magnetic field is
! Methods for generating a continuous alternating current magnetic field at 0 Ooe include the solenoid method, electromagnet method, etc., and it is best to select the most suitable method in terms of installation costs and carrying costs. Also, the intermediate annealing process J3 and 8 (the direction of the alternating current magnetic field applied to the opposite direction) may be parallel to the rolling direction of the steel plate.

The plate that has undergone intermediate annealing as described above is subjected to final cold rolling at a reduction rate of 40 to 80%, and is finished to a target final plate thickness of 0.15 to 0.501181. The reason why the final cold rolling reduction is limited to 40 to 80% is as follows. That is, in this invention, 0 after intermediate annealing
By adjusting the circles, the crystal structure is made uniform and the (110)[001] orientation is encouraged to accumulate in the primary recrystallized structure, but this effect is not effective at a final cold rolling reduction of less than 40% or more than 80%. However, it can only be achieved in the final cold rolling reduction range of 40 to 80%.

Next, the final cold-rolled sheet was heated to 750 to 8 in a wet hydrogen atmosphere.
Decarburization annealing is performed in a temperature range of 50℃, and the CD is 0.003.
% or less. Then, after applying an annealing separator such as MgO, final annealing is performed. This final annealing is performed for the purpose of sufficiently growing and developing secondary recrystallization in the (110)[001] orientation, and at the same time purifying and removing impurity elements such as s, se, and N added as inhibitors to the steel sheet. This final annealing is usually performed by box annealing.
It is carried out by raising the temperature to a high temperature of 000℃ or higher, but according to the method of Japanese Patent Publication No. 13469/1983 proposed by the present applicant, it is heated for about 101I in the temperature range of 820 to 920℃ where secondary recrystallization occurs. After the secondary recrystallized grains are sufficiently grown by maintaining the above conditions, it is desirable to adopt a method of subsequently performing purification annealing for the purpose of removing impurities at a high temperature of 1000° C. or higher.

By going through the above-mentioned steps, it is finally possible to stably obtain a unidirectional silicon steel sheet product with excellent magnetic properties, which is the object of the present invention.

Examples of this invention will be described below.

Example 1 CO,043% for 9i 3.05%; and Si
3.25%, against CO,045%; and 9i
It consists of three levels of composition: 3.45% and CO, 048%, all of which act as inhibitors! ,ln O,07
%, 3 e O, 025%, and S b O, 028%, two continuous cast slabs each with a thickness of 20011111 were produced by water melting, heated to 1380°C for 1 hour, hot rolled to a thickness of 2.511 II, and formed into coils. I rolled it up. Next, these hot-rolled coils were held at 980°C for 30 seconds, and then cold-rolled for the first time to 0.
．． 75rm thickness, and then during intermediate annealing at 950°C for 2 minutes, the initial recrystallization temperature during the temperature rise was 500~7oo.
It was processed in a humidity range of 0.015°C with an alternating current magnetic field adjusted to two levels of 0.01500 oe, and then further cold rolled to a final thickness of 0.30 mm with a final cold rolling reduction of 60%. Then 80C
After decarburization annealing in wet hydrogen of 1) J! ] After applying an annealing separator mainly composed of 0, as final annealing,
A 4-temperature process of holding at 860° C. for 30 hours, followed by a 10-hour treatment at 1200° C., was carried out, and then an insulating coating was applied to produce a unidirectional silicon steel sheet product.

Table 1 shows the results of measuring the magnetic properties of each product obtained.

As is clear from Table 1, j8
It is clear that the obtained products have superior magnetic properties compared to the products of comparative examples.

Example 2 Si 3.096: versus T GO, 040%;
Oyo' CFSi 3.20% vs. GO, 043%;
It consists of three levels of composition: Oyo U Si 3.4096 2 and Si cO-047%, all of which have U as an inhibitor.
200 containing n O,068% and S O,023%
Two continuous cast slabs each having a thickness of 1III and 11 were produced by aqueous melting, heated to 1360°C for 1 hour, hot rolled to a thickness of -2.5III and wound into a coil. These hot-rolled coils were then pickled and cold-rolled to a thickness of 0.75 mm, followed by intermediate annealing at 900°C for 5 minutes at a temperature range of 500 to 70°C at the initial stage of recrystallization during heating. The alternating current magnetic field was adjusted to two levels, 0 and 500 oe, and then the final cold rolling was further performed to a thickness of 0.30n+a+, and the final cold rolling reduction was 6.
It was set to 0%. Next, after decarburizing annealing in wet hydrogen at 80°C, an annealing separator mainly composed of MQO was applied, and a final annealing was performed in which the temperature was immediately raised to 1170°C in a box annealing and held for 15 hours. A product of unidirectional silicon steel plate was obtained. Table 2 shows the results of examining the magnetic properties of these products.

As shown in Table 2, it is clear that the product obtained by the method of the present invention in Example 2 also has superior magnetic properties compared to the product of the comparative example.

As described above, according to the method of the present invention, by applying an alternating current magnetic field of 1QQoe or more in the initial stage of recrystallization during intermediate annealing before final cold rolling, unidirectional 11 silicon having superior magnetic properties than conventional ones can be produced. The phase plate can be obtained reliably and stably, and the process is the same as the conventional one except for the addition of AC @, so the rise in the concentration is small, and it is a unidirectional silicon that is efficient and efficient. The feed board can be lifted by 1'.

[Brief explanation of the drawing]

Figure 1 shows a comparison of the recrystallization rate during the heating process during intermediate annealing before the final cold rolling and the X-ray density of the (110) and (222) planes between the conventional method and the method of the present invention. Figure 2 shows that an alternating current magnetic field is applied at the initial stage of recrystallization in the temperature raising process of the intermediate annealing process, and the strength of the magnetic field in the 1 and 2 fields increases the magnetic flux of the product and the iron loss. 50 (this is a 0 relationship diagram).

Claims (1)

[Claims] GO, 025~0.10% (weight 196, Q downward L; ), Si2.5~4.0%, MnO, 02~
A step of hot rolling a silicon steel slab containing 0.15% and one or both of s and se in a total content of 0.008 to o, oao%, and a hot rolled sheet thereof. Intermediate annealing within the temperature range of 750-1100℃ for 2
The cold rolled sheet is then subjected to decarburization annealing and a final process. A method for producing a unidirectional silicon steel sheet comprising the step of annealing, the temperature being within a temperature range of 500° C. or higher and below the magnetic transformation point at the initial stage of recrystallization of the steel sheet in the intermediate annealing step before the final cold rolling. A method for producing a unidirectional silicon steel sheet, characterized in that an alternating current magnetic field of 100 Oe or more is applied parallel to the rolling direction of the steel sheet.