FI59618C - FREQUENCY REFRIGERATION OF CRYSTALLINE CONDITIONERS EL-STAOLSKIVOR MED HOEG MAGNETIC INDUCTION - Google Patents

Description

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Patent- OCh refisterstyrelsen '' Anaekan utla | d och utl. * Krlft * n publlcand 29 · 05.81 (32) (33) (31) PjT ^ ttty privilege —Bsgird prloritat (71) Kawasaki Steel Corporation, no. 1-28, 1-Chome, Kitahonmachi-Dori,

Fukiai-ku, Kobe City, Japan-Japan (JP) (72) Takuichi Imanaka, Chiba City, Takahiro Kan, Chiba City,

Yoshio Obata, Chiba City, Toru Sato, Chiba City, Japan-Japan (jP) (7 ^ +) Leitzinger Oy (5 ^) Method for the production of crystal oriented electrical steel sheets with high magnetic induction - Förfarande för framställhing av kristallorienterade el-stälskivor med hög magnetic induction

The invention relates to a method for producing electrical steel sheets 2 having an (110) / 001 / orientation and a Bg value of more than 1.85 VJb / m.

It is known in the art to produce crystal oriented electrical steel sheets with improved magnetic properties and lower iron losses compared to normal silicon steels. For example, U.S. Patent No. 3,556,873 discloses a process for preparing a selenium-second silicon steel having a (110) / 001 / orientation prevailing and utilizing the ability of manganese selenide to provide the required crystal orientation under certain conditions. Since the mere addition of selenium does not necessarily lead to the required crystal orientation, the known process uses very sulfur-poor silicon steel as a starting material, in which the concentrations of carbon, manganese and selenium must be carefully dimensioned relative to each other. In particular, in view of the required manganese selenide formation, the manganese content must be carefully dimensioned relative to the selenium content to ensure that the addition of selenium does indeed provide the required crystal orientation. As a result, the known process uses a starting material containing 0.02 to 0.07% carbon, 2 to 4% silicon, at least 0.045% manganese, less than 0.008% sulfur and 0.01 to 0 * 1% selenium. This starting material is first hot rolled, then normalized and cold rolled to intermediate dimensioning, followed by further normalization and cold rolling to final dimensioning. After the final cold rolling, the material is subjected to carbon removal annealing and final purification and texturing annealing, using temperatures up to 1117 ° C.

This known method is disadvantageous in that the BR value of the crystal-oriented electrical steel sheet produced by it can in no case exceed 1.85 Wb / m, and temperatures of more than 1000 ° C are required for final annealing, resulting in high energy consumption and a high need for refractory annealing furnace linings. A further disadvantage of the known method can be seen in the fact that the starting material must contain manganese as an essential component. Thus, the known method is limited to the treatment of manganese-containing electrical steels.

DT application 1 920 968 discloses a method for treating magnetic disks with high magnetic induction based on the separation of aluminum nitride into crystal growth inhibitors. For this reason, the starting material of this known process must contain aluminum and nitrogen in suitable proportions. In this known method, such a starting material is hot-rolled and then finalized by repeated cold rolling and intermediate annealing, whereby before final cold rolling at a reduction rate of 65 to 95%, intermediate annealing is carried out at a γ-change temperature from which the material suddenly. cooled to a temperature below 750 to 950 ° C so that the separation of the aluminum nitride takes place in the required amount and form. Finally, final annealing to more than 800 ° C takes place to effect secondary recrystallization in the rolling direction. To the extent that the separation of aluminum nitride (A1N), which forms the basis of the known method, is not prevented, the starting material may also contain small amounts of sulfur, selenium, etc. However, said application discloses that it is AIN separations capable of selective crystal growth by rolling.

This known method is disadvantageous in that it does not. be able to produce steel plates with a Bg value greater than. 1.8 VJb / m, in addition to the disadvantage that numerous heat treatment steps have to be performed to achieve the required A1N separation.

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The object of the invention is therefore to provide a method by which it is possible in a technically simple manner to produce crystal-oriented electric plates with a Bg value of more than 1.85 Wb / m.

To achieve this object, the process according to the invention is characterized in that the starting material is silicon steel with less than 0.06% carbon, less than 4% silicon, 0.005 to 0.2% antimony, 0.008 to 0.1% selenium and / or sulfur. , hot-rolled, annealed, and possibly repeated cold-rolled and intermediate-annealed, rolled to a final thickness at a reduction rate of 40 to 85% in the final cold-rolling, and that the cold-rolled sheet is subjected to 8 ° C C.

Most preferably, the starting material contains 0.02 to 0.2% manganese, it is further preferred that the starting material contains less than 0.5% chromium, niobium, vanadium, tungsten, boron, titanium, zirconium or tantalum.

Preferably, the starting material contains tellurium, in which case selenium and / or sulfur are partially replaced by tellurium.

In this case, it has further proved advantageous that the amount of antimony in the starting material is 0.012 to 0.045% and that the final cold rolling is carried out with a degree of reduction of 50 to 77%.

The technical progress achieved by the invention is primarily seen in that the method according to the invention makes it possible to produce crystal-oriented steels with previously unattainable advantageous magnetic properties, i.e. a Bg value over, in a technically simple and economically advantageous manner.

1.85 Wb / m 2.

Said Bg value is to be understood as magnetic induction with a magnetic field strength of 800 A / m.

Generally, in the manufacture of crystal oriented electrical steel sheets, the hot rolled starting materials contain a suitable amount of inhibitors that inhibit normal crystal growth during annealing, and the starting materials are cold rolled to a final sheet thickness, with the required amount of intermediate annealing performed at 4,59618. The sheets thus treated are then subjected to carbon removal and secondary recrystallization annealing at a high temperature of 1100 to 1200 ° C to selectively effect crystal growth having a (110) / 001 / orientation. The growth of crystals which do not correspond to said trend is inhibited by small separations of manganese sulfide, manganese selenide or aluminum nitride or the like separated at the crystal boundaries.

In order to carry out the process according to the invention, it is necessary that antimony and at least one of the substances selenium and tellurium be present in the silicon steel used as starting material.

The use of antimony to control selective crystal growth in primary crystallization is already known from Japanese Patent Publication 8214/64, in which case the starting material should contain 0.005 to 0.1% antimony.

The invention is based on the guiding principle that the inhibitory effect of antimony on the crystal growth of primary crystals whose orientation differs significantly from that of (110) / 001 / is considerably enhanced by the use of selenium or sulfur. After repeated cold rolling, when the starting material is at the desired final sheet thickness, the treated sheet is subjected to primary recrystallization annealing, which also results in carbon removal. The associated final annealing serves to grow secondary recrystallized crystallizations with the (110) / 001 / orientation.

The invention will now be described in more detail with reference to the accompanying drawings, in which Figures 1A and 1B are diagrams illustrating the relationships between sulfur and selenium concentrations and magnetic induction.

Figure 2 is a graph illustrating the relationship between antimony concentration and Bg as determined by the S and Se portions 11a.

Fig. 3 is a diagram illustrating the dependence of the Bg value on the secondary crystallization temperature with sample A treated according to the invention and with sample B treated so far.

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Fig. 4 is a graph illustrating the ratio of Bg to iron loss at a given antimony content in a finished product, and Fig. 5 is a graph illustrating the effect of rolling times on Bg using selenium- and antimony-containing starting material according to the invention and exclusively selenium-containing starting material.

Figures 1A and 1B show typical dependences between sulfur and selenium contents and magnetic induction Bg for products made as follows: 3 mm thick hot-rolled sheets melted in an electric furnace and containing about 3% silicon and about 0.03% antimony , annealed for 5 minutes at 900 ° C. Thereafter, these sheets were cold-rolled with a thickness reduction of 60 to 85% while performing a 5-minute intermediate annealing at 950 ° C. In the last cold rolling, the thickness of the sheets was reduced by 40 to 80%, reaching a final thickness of 0.30 to 0.35 mm. The plates were decarburized in a humid hydrogen atmosphere at 820 ° C and secondary re-annealing annealing was performed at 850 ° C and oven annealing at 1200 ° C. With a selenium content of 0.012 to 0.045% and a sulfur content of 0.012 to 0.045%, such a high B0 value of 2.90 Wb / m was achieved.

The diagram in Figure 2 illustrates the magnetic induction of the obtained product, which was treated as follows: In an electric furnace, a molten steel ingot containing about 3% Si, 0 to 0.20% Sb, 0.02 to 0.04% Se, 0.001 to 0.008% or 0, 02 to 0.05% S, in the same steps as shown in Figure 1. It can be seen from Figure 2 that when at least one of the substances Se and S is contained in a silicon steel ingot containing 0.005 to 0.20% Sb, the Bg values are better than in those cases with 0.005 to 0.20% Sb alone, 0.02 to 0.05% S alone or 0.02 to 0.04% Se alone. When the Sb content is less than 0.005%, even if Se and / or S are added, then 2

Bg values do not exceed 1.85 Wb / m, and also if Sb exceeds 0.2%, then the Bg value decreases and the magnetic properties deteriorate. When the amount of Sb is more than 0,005% but less than 0,2%, the value of BD can be

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can be improved. In particular, when Sb is in the range of 0.01 to 0.1%, then the Bg value is not significantly affected by the Sb content and Sb in the range of 0.02 to 0.04%, the highest Bg value can be achieved.

On the other hand, as shown in Fig. 1A, when the sum of the amounts of Se and S is 5961 8 less than 0.008%, the desired value of Bg cannot be obtained. A large increase in the amounts of Se and S hardly or not due to the value of Bg, but hot brittleness can occur in hot rolling and iron loss. Thus, the excessive addition of substances Se or S is not recommended in view of industrial production. Thus, the sum of the amounts of the upper bound substances Se and S has been determined to be 0.10%.

C is limited to less than 0.06%. This limitation has been determined because of the need for the economics of carbon removal, since the C content must be reduced to less than about 0.005% in the carbon removal step in order to develop the desired secondary crystals. The amount is limited to less than 4% to ensure good cold workability.

As explained above, it is essential in the present invention that Sb and at least one of the substances Se and S be contained in silicon steel, but it is clear that well-known substances which are added to ordinary silicon steels are present. For example, it is recommended to use 0.02 to 0.2% Mn. In addition, it is permissible to replace Se or S Te, which is a well-known inhibitor of primary crystal growth, in addition to which Te can be added. Furthermore, the inhibitors Cr, Nb, V, W, B, Ti, Zr and Ta can be added in an amount of less than 0.5%. Low aluminum concentrations, e.g. less than 0.02%, used to prevent oxidation are not harmful. However, Ai, the residual amount in the finished product is usually less than 0.005%.

The silicon steel ingot of the present invention is usually produced by a well-known steelmaking process, and the silicon-steel ingot thus produced is hot-rolled by a well-known method, and the hot-rolled sheet thus obtained is subjected to one release stage and at least one cold-rolling step step to develop secondary recrystallization cores with an (110) / 001 / orientation.

The ways to perform these sequential steps are explained in detail below.

An LD converter, an electric furnace, a furnace and other known steelmaking processes can be used to melt the raw material of the present invention, and a vacuum treatment or vacuum melting process can be used together. In addition, the means for making the ingot, i.e. the ingot, can be provided by ordinary mold casting and continuous casting.

In the present invention, it is essential to use a raw material containing Se or S as an addition to the amount of Sb, but the addition of Se or S to the substance has already been proposed and this addition can be arranged by any known process. For example, substances may be added to the molten steel in the manufacture of the ingot and further arranged to be provided by adding an appropriate amount of Se or S to the emission separator for use in the final discharge.

The obtained steel ingots or strips made by continuous casting can be hot rolled by a well-known method. In general, the strips and sheets are hot rolled and developed in continuous hot strip rolling machines, generally after heating, preferably to a temperature of 1200 to 1350 ° C. The thickness of the hot rolled plate depends on the next cold rolling step, but is generally about 2-5 mm.

The hot-rolled sheet is then cold-rolled and cold-rolled according to the present invention is performed at least once, but in order to obtain a high value of the product Bg of the present invention, it is necessary to pay full attention to the final cold-rolled amount.

Figure 5 is a graph illustrating the relationship of the Bg value to the final cold rolling rate when the molten steel contains about 3% Si, about 0.06% Mn, 0.03% C, and 0.003% S is added (a) 0.018% Se and 0.030% Sb and (b) 0.015% with It to produce ingots each treated in the same manner as described in connection with Figures 1 and 2. It can be seen from this figure that according to the present invention, a high Bg value in the material can be achieved in the range of 40 to 85% with the amount of final cold rolling. In particular, a cold rolling rate of 50 to 77% gives a B 2 value of more than 1.90 Wb / m. On the other hand, when the final cold rolling rate exceeds 85%, the primary recrystallized cores with a trend very different from the (110) / 001 / trend are also developed, and the preferred secondary recrystallized cores are not developed satisfactorily. As a result, the value of Bg has rapidly deteriorated. Moreover, when said amount is less than 40%, a large increase can be obtained with the secondary recrystallized cores, but their (100) axes become scattered, with respect to the rolling direction, and a Bg value higher than 1.85 Wb / m cannot be achieved.

Cold rolling is usually carried out twice and intermediate annealing between 850 to 1100 ° C is carried out between two cold rolling mills. In the case of the first rolling, the reduction rate is about 60 to 85%. However, it is possible that the hot-rolled sheets are reduced to the final size in one cold-rolling step, whereby the BQ value is more than 2 ° 1.85 Wb / m, and this can be achieved. In the case where the hot-rolled sheet is annealed at a temperature of 850 to 1100 ° C to make the hot-rolled structure homogeneous, a favorable result can be obtained. These annealing is usually performed in a continuous furnace, but may also be arranged by other means, such as box annealing and the like.

The steel sheet having the desired sheet thickness after final cold rolling is subjected to carbon removal annealing. This annealing tends to change the cold-rolled structure to the primary recrystallized structure and at the same time remove C, which is detrimental to the growth of secondary recrystallized cores in the (110) / 001 / final discharge trend. For example, said annealing is performed in a wet hydrogen temperature at 750 to 850 ° C for 5-15 minutes and some other known process can be used.

The final emission is performed in order to increase the secondary recrystallized cores with the (110) / 001 / orientation and to reduce residual impurities which are unpleasant for the iron loss value. In normal practice, the temperature is raised directly without delay to a temperature higher than 1000 ° C by box annealing and this temperature is maintained until the purposes are achieved. However, in accordance with the present invention, secondary recrystallization annealing and purification annealing are provided in different temperature ranges. Namely, the secondary recrystallization annealing temperature is desirably as low as possible if secondary recrystallization cores can be developed, and by such means the value of Bg is raised much higher than by maintaining a high temperature in ordinary steps. The value of Bg is also high enough if the secondary recrystallization annealing is complete and complete, but in order to calculate the iron loss of the product, it is desirable to then increase the purification annealing at a high temperature, keeping the temperature not in the γ range. This temperature for cleaning annealing depends on the Si content. This final annealing is performed by box annealing using an annealing separator such as magnesium oxide.

Figure 3 depicts the result obtained for raw material A (plate thickness: 3.0 mm) 5961 8 containing 3.3% Si, 0.02% Sb, 0.015% Se and for ordinary raw material B (plate thickness: 2.0 mm) containing 3.3% Si, no increase in Sb and 0.015% Se. Both feedstocks A and B are subjected to primary cold rolling with a reduction of 70%, intermediate annealing at 950 ° C for 5 minutes and then secondary cold rolling with a reduction of 67% for A and 50% B to give a final dimension of 0.30 mm and then descaling in wet hydrogen at 820 ° C. The cold-rolled sheet is then subjected to a secondary recrystallization annealing at 840 to 960 ° C for 80 hours and then a final annealing at 1180 ° C for 5 hours.

As can be seen in Figure 3, when the temperature for secondary recirculation is lower, the magnetic property of Bg is greatly improved. In addition, the silicon content including Sb and Se is particularly noticeable in the improvement of the Bg value.

Figure 3 illustrates that the secondary recurrence. the annealing temperature, higher than 930 ° C, does not completely improve the Bft value and it is difficult to reach a Bg value higher than 1.85 Wb / m. On the other hand, secondary recrystallization also occurs by annealing at a temperature lower than 800 ° C, but this takes a longer time and is not economically good. Thus, in accordance with the present invention, the secondary recrystallization temperature is preferably 800 to 920 ° C. According to another principle of the invention, there is complete development of the secondary recrystallization core at a lower temperature and for this purpose a temperature of 800 to 920 ° C is maintained for 10 to 120 hours or the temperature is gradually raised in this temperature range, for example by 0.5 to 10 ° C / h.

As is already known, Se and S contained in a steel plate, after having acted to increase the secondary recrystallization core in the (110) / 001 / final discharge direction, are removed or reduced as much as possible, as these substances are annoying in terms of iron loss. The removal of Se and S can be achieved by providing annealing in I 2 for a long time, and especially when Si is higher than 2.0%, by annealing at a temperature higher than 1000 ° C, S and Se are removed. On the other hand, Sb has its own activity, inhibiting the growth of primary recycled nuclei, and, as shown in Fig. 4, even if Sb remains in the steel plate, it does not contribute to the deterioration of the iron loss value. This is very characteristic and not. not necessary in particular, to remove Sb on final annealing.

10 5961 8

The following examples are presented for the purpose of illustrating the present invention and are not intended to limit it. The term as used herein means weight.

Example 1

Silicon ingot containing 0.020% C, 2.90% Si, 0.06% Mn, 0.030% Sb and 0.020% It was pre-rolled and then heated to 1250 ° C for 1 hour, followed by a continuous hot rolling step to a thickness of 3 mm, primary cold rolling with a reduction of 75% and then annealing at 900 ° C for 5 minutes and finally cold rolling with a reduction of 60% to a thickness of 0.3 mm. The plate was then decarbonated in wet hydrogen at 820 ° C for 5 minutes and finally annealed. In the final annealing, the temperature was maintained at 870 ° C for 20 hours to fully develop secondary recrystallized cores, and then the temperature was raised to 1200 ° C and maintained at this temperature for 5 hours. The magnetic properties of the resulting product were as follows: B8: 1.91 wb / m2 W17 / 50: w / k *

Example 2

Silicon ingot containing 0.03% C, 2.95% Si, 0.056% Mn, 0.022% Sb, 0.009% S and 0.015% It was pre-rolled and then heated to 1320 ° C for 1 hour, followed by a continuous hot rolling step to a thickness of 2 mm and then once cooled and continuously annealed under N 2 for 5 minutes at 900 ° C. Primary cold rolling was then performed at a reduction of 50% to obtain a plate having a thickness of 0.30 mm. Descaling was then performed at 820 ° C for 5 minutes and further ordinary box annealing was performed at 1180 ° C for 5 hours. The result was a silicon steel plate having the following properties.

Bg: 1.88 wb / m ^ W17 / 50: 1'il * ”/ k *

Example 3

Silicon steel casting containing 0.025% C, 3.25% Si, 0.019% Sb, 0.020% Se and a residual amount of S (0.004%) were hot rolled to a thickness of 3 mm and passed at 97061 C for 5 minutes, then primary cold rolling was performed with a reduction amount. 75% and secondary villages rolling at a reduction rate of 64% (0.3 mm thickness) and between the two cold rolls, intermediate annealing was performed at 900 ° C. Decarbonation annealing and final discharge were then performed. In this case, a temperature of 860 ° C was maintained for 50 hours to completely grow the secondary recrystallized cores, and then 1180 ° C was maintained for 5 hours. The characteristics of the resulting product thus obtained were as follows.

Bfl: 1.91 wb / m2 W17 / S0: ^ 11 w / k?

Example 4

A continuous cast plate having a composition of 0.015% C, 2.90% Si, 0.08% Sb, 0.03% Se and a residual amount of S (0.003%) and 0.05% Mn was hot-rolled to a thickness of 3 mm. The resulting plate was subjected to primary cold rolling with a reduction of 60%, intermediate annealing at 950 ° C and then secondary cold rolling with a reduction of 75% (0.3 mm thickness). This was followed by degassing annealing and a final annealing at 1200 ° C for 5 hours. The characteristics of the product thus obtained were as follows.

Bg: 1.86 wb / m2 ^ 27/50 'w / kg

Example 5

After obtaining a silicon steel hot-rolled plate (3 mm thick) containing 0.040% C, 2.90% Si, 0.015% Sb, 0.02% Se and 0.03% S, primary cold rolling was performed with a reduction of 78%, intermediate annealing at 950 ° C and then secondary cold rolling at a reduction of 50% to obtain a sheet having a thickness of 0.30 mm. After decarburization annealing, the plate was gradually heated from 800 ° C to 900 ° C for 30 hours at 3 ° C / h, and the temperature was maintained at 1180 ° C for 5 hours. As a result, a silicon-steel sheet having the following properties was obtained during the final annealing.

Bg: 1.93 wb / m2 '' 17/50: 1.22 w / kp: 5961 8

Example 6

A steel ingot containing 0.025% C, 0.8% Si, 0.020% Se and 0.030% Sb was pre-rolled and hot rolled to give a plate with a thickness of 2.0 mm. After annealing at 1000 ° C for 5 minutes, cold rolling was performed at a reduction of 60% to obtain a plate having a thickness of 0.8 mm. Further, after decarbonation annealing, a final annealing in an H 2 atmosphere at 900 ° C was performed for 2 * 4 hours. The result was a product having the following characteristics:

Bg: 1.98 wb / m2

Example 7

Silicon ingot containing 0.03% C, 3.25% Si, 0.05% Mn, 0.030% Sb and 0.02% It was prepared in an LD converter, pre-rolled and heated at 1320 ° C for 60 minutes. After hot rolling to a thickness of 3 mm, the plate was annealed at 900 ° C for 5 minutes. Primary and secondary cold rolling with a reduction of 71% and 65%, respectively, and intermediate annealing at 920 ° C for 5 minutes reduced the plate thickness to 0.30 mm, and then the plate was decarbonated in wet hydrogen at 820 ° C for 5 minutes. 850 ° C was maintained for 80 hours to completely grow the secondary recrystallized cores. Finally, the plate was annealed at 1180 ° C for 5 hours. The magnetic properties of the resulting product were as follows.

Bg: 1.92 wb / m2 W ': 1.07 w / kR

Claims (8)

13 5961 8 A process for the production of electrical steel sheets with a (110) / 001 / - 2 orientation and a Bg value of more than 1.85 WB / m, characterized in that the starting material is silicon steel with less than 0.06% carbon, less than 4 % silicon, 0,005 to 0,2% antimony, 0,008 to 0,1% selenium and / or sulfur, hot-rolled, annealed and, if necessary, by repeated cold-rolling and intermediate-annealing, at a reduction of 40 to 85% in final-cold-rolling to final thickness, and that the cold-rolled sheet is subjected to decarburization annealing and annealing for 10 to 120 hours for secondary recrystallization at temperatures of 800 to 920 ° C. Process according to Claim 1, characterized in that the starting material contains 0.02 to 0.2% of manganese. Process according to Claim 1, characterized in that the starting material contains less than 0.5% of chromium, niobium, vanadium, tungsten, boron, titanium, zirconium or tantalum. Process according to Claim 1, characterized in that the starting material contains tellurium. Process according to Claim 1, characterized in that the selenium and / or sulfur are partially replaced by tellurium. Process according to Claim 1, characterized in that the amount of antimony is 0.012 to 0.045%. Process according to Claim 1, characterized in that the final cold rolling is carried out with a reduction of 50 to 77%. Process according to one of the preceding claims 1 to 7, characterized in that the secondary crystallized steel sheets are annealed to remove sulfur and selenium impurities above 1000 ° C in a hydrogen atmosphere.