DE2522727A1 - METHOD FOR MANUFACTURING GRAIN ORIENTED SILICON STEEL SHEET - Google Patents

Description

PATENT LAWYERS A. GRUNECKiIR

DiPL.-INQ.

H. KINKELDEY ^

2522727 ~ w. Stockmair

DR.-1NQ. AeE (CALTCCH)

K. SCHUMANN

. DR. RER. NAT. · DIPl PHVS.

P. H. JAKOB

DIPL.-ΙΝΘ.

G. BEZOLD

DR. RER. NAT. · DIPU-CHEM.

MUNICH

E. K. WEIL

DR. RSR. OEC. INTO THE.

LINDAU

MUNICH? 2

MAXIMILIANSTRASSE 43

May 22, 1975

USS ENGIITEEES AND CONSULTANTS, INC.
Grant Street, Pittsburgh,
Pennsylvania / USA

Process for producing grain-oriented silicon steel sheet

Process for producing grain-oriented silicon steel sheets, which for transformers and other electromagnetic Devices used must be carefully guided or controlled to the maximum extent an easily magnetizable preferred orientation in the finished product and therefore optimal anisotropic one to achieve magnetic properties. Technically executed processes focus on the production of a steel

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TELEPHONE ((MU) SS 58 βθ TELEX OO -703SO TBlEROAMME

252272?

with a very carefully adjusted or monitored chemical composition, with in steel typically 2.5 to 3.5 % silicon, 0.07 to 0.12% manganese, about 0.025% sulfur, less than 0.03% carbon and it contains less than 0.015 % phosphorus. Slabs made from such steel are hot rolled to a finished hot strip dimension of about 2.032 mm. The hot rolled steel is then cleaned and cold rolled to final dimensions using one of several working methods. Cold rolling is usually carried out with the aid of two cold rolling processes with intermediate annealing to a final dimension between 0.254 and 0.381 mm. The cold rolled sheet is then subjected to a decarburization anneal to induce primary recrystallization and decarburization, followed by a carefully monitored high temperature final box anneal to induce secondary recrystallization in the preferred orientation.

The creation of a well-developed, oriented peing structure depends not only on careful monitoring of the related process parameters, but also from careful monitoring of the chemical composition of the steel material. So it is For example, it is well known in the art that a fine, dispersed, deposited phase, such as manganese sulfide, during the final orientation annealing must be available in order to be used as To serve grain growth inhibitor and consequently «ine oriented Promote secondary recrystallization. Without such a precipitation or separation phase, the final annealing would take place considerable grain growth of the larger primary grains with little or no secondary recrystallization to create an oriented peing structure. And €; rer-

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On the other hand, such a deposition phase is of no use unless it is during or after the hot rolling of the slab occurs to sheet metal, since previous heat treatments, rough rolling, etc. lead to such deposits inside the grains of the hot rolled sheet are quite large and not well dispersed. To avoid this problem In the technical version, a relatively high preheating is used for the hot rolling of the slabs, which that is, temperatures of about 1371 ° C are used to dissolve the particles of the deposition phase, which then be deposited again during or after hot rolling.

Although the above-mentioned high temperature hot rolling is effective in loosening those contained in steel Sulfides, so they are hereinafter referred to as grain growth inhibitors can be eliminated, this mode of operation is costly, time consuming and arduous, in particular in view of the destructive influence of such high temperatures on the refractory lining and the supporting structure of the "heating furnace for the slabs. In addition, it is to be regarded as disadvantageous in the known mode of operation that an excessive Oxidation of the slab surfaces takes place during such heating. In the development of procedures which not that high; Requiring reheat temperatures for the slabs is considerable research has been invested. Various such methods have been proposed or patented. These procedures provide. usually relies on the use of other deposits or combinations thereof as grain growth inhibitors. None however, this method has proven to be technically feasible.

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U.S. Patent 3,671,337 was recently taught that lower slab reheating temperatures can then be used when the amount of manganese sulfide in the steel is reduced, provided an aluminum nitride phase is sufficient to enhance the manganese sulfide as a grain growth inhibitor. Although Exceptionally good results can be obtained with the help of this procedure, it is more precise because of the need Monitoring and because of the fact that the yield of high quality products is quite low. In addition, the high aluminum content seems to be noticeable during the pouring process, which is a nuisance is due to the reoxidation of the same in the absence of extraordinary precautions during decanting.

The present invention is based on the development of a new and improved method for producing grain-oriented Silicon steel sheet, which allows the use of lower slab reheating temperatures prior to hot rolling without adversely affecting the yield of high quality products. The application lower slab reheating temperatures lead to many benefits, including a reduction in heat input to the reheating furnace, to reduce slab deterioration during reheating, to Reduction of the so-called sweating or the extent and speed of oxidation, to reduce of the resulting output losses to reduce slag accumulations in the furnace, to reduce damage on the furnace lining and on the furnace support frame, whereby the Extending furnace life, increasing furnace throughput, increasing productivity

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to increase the service life of the ingot and hot rolling stands and to reduce the duration of the heat treatment for sulfur removal during box annealing, whereby the productivity of existing box annealing facilities is increased.

It is an object of the present invention to provide a new and improved method for producing grain oriented Silicon steel sheet to create which lower the application Slab reheating temperatures allowed, so much so to partake of the advantages mentioned above. Another object of the invention is to provide a method for producing of grain-oriented silicon steel sheet, in which a low manganese and / or sulfur content in Combination with low, permanent oxide contents made use of is to avoid the use of lower slab reheating temperatures without adversely affecting the magnetic properties of the product.

Another object of the invention is to provide a method for producing grain oriented silicon steel sheet create in which of an effective deoxidation step in connection with protective measures to prevent co-oxidation Use is made in this way to lower the amounts of manganese sulphide excretions of their effectiveness as grain growth inhibitors and thus the use of lower slab reheating temperatures before hot rolling. Yet another object of the present invention is to provide a method for producing grain-oriented silicon steel sheet, in which with the aid of effective deoxidation processes the effectiveness of the precipitated manganese sulfide for inhibition undesired grain growth is promoted in order to

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This is a way of reducing the amount of these deposits in the steel.

The invention relates to a process for producing grain-oriented silicon steel sheet with excellent magnetic properties, in which the contents of manganese and sulfur are set in a decisive manner so that the product of the manganese content (% by weight) multiplied by the sulfur content ( % By weight) is between 0.0007 and 0.0012. Aluminum is added to the deoxidized steel immediately before it is poured to prevent the formation of insoluble _? to reduce oxidic precipitations in the cast steel to a minimum, whereby the amount of added aluminum is limited so that significant aluminum contents remaining in solution in the dissolved steel are avoided. The slab obtained from the above-mentioned steel can then be preheated to a temperature of 1166 to 130 ° C. before hot rolling without any loss in the quality of the magnetic properties.

In the accompanying drawing, the solubility product of manganese sulfide is shown as a puncture of the temperature.

In the manufacture of grain-oriented silicon steel sheet it has already been noted that the development of a well-oriented IF insert depends on the final anneal from the presence of a fine dispersed precipitation phase within the primary grain. If these deposits are present in sufficient quantities, they are used during the final annealing as Grain growth inhibitors, causing them a secondary recrystallization more than a non-specific grain growth of the primary grains through grain boundary migration. Albeit different different substances are provided for these deposits

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like VN, (TiC, MnS, are "primarily used in large-scale operations As a result, in the art, it has been necessary to produce a silicon steel with 0.07 to 0.11% manganese and 0.02 to 0.04 % sulfur, with these amounts of manganese and sulfur generally sufficient manganese sulfide can be formed to to have the necessary grain growth inhibitor deposition available, generally between 0.055 and 0.11% manganese sulfide In order to function effectively as a grain growth inhibitor, it is known that the manganese sulfide or other such deposition phase must be finely divided in the steel, in which the small particles serve as a barrier to grain boundary migration and thus grain growth during the primary crisis to prevent crystallization and to promote grain growth of the fi10 | <001> grains only during the secondary recrystallization. Extensive hot deformation of the solidified steel results in these deposits growing considerably and becoming so concentrated intergranularly that the deposits are no longer effective as grain growth inhibitors in the desired manner. Accordingly, it is also important that the deposited phase is one that can be dissolved in solid solution and that it is so dissolved during the reheating of the slab so that a re-precipitation of this phase in the form of finely divided particles during or after the final hot rolling process, ie the rolling of the slab into hot strip with finished dimensions, occurs. It can be seen that in the prior art operation described above, a

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Excess manganese is present in the steel produced in a known manner which exceeds that manganese content which is required for a stoichiometric reaction with sulfur for the purpose of forming manganese sulfide. For example , as mentioned above, 0.02% sulfur would almost completely react with about 0.035% manganese, leaving a significant amount of unreacted manganese. This excess manganese is useful in preventing the steel from becoming hot. However, since this excess manganese is in solution in the solidified steel, it reduces the ease with which deposited manganese sulfide can be dissolved when the slabs are reheated. The difficulty of dissolving the precipitated manganese sulfide is proportional to the amount of excess, unreacted manganese that is already in solution.

Since the process of dissolving manganese sulfide is temperature-dependent This process can be described with the help of the following well-known reaction equation:

Never ⁺ EU

According to this equation, excreted MnS goes during the Dissolving process in manganese and dissolved sulfur dissolved individually in the solid steel. In accordance with the agreements to consider the energetic relationships in such reactions, the tendency to such dissolution reactions can be expressed as follows;

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If the activity of the excreted MnS is assumed to be constant, so the difficulty of solving MnS is proportional to the product of the percentage of Manganese multiplied by the percentage of sulfur which Product is referred to as the solubility product. This means that the necessary for a complete solution The higher the temperature. The greater the solubility ■ product is. As a result, an excess manganese content that is above that for a stoichiometric compound of manganese and sulfur, the solubility product is increased and consequently also the one for the complete dissolution increases the required temperature. With regard to more detailed explanations regarding the solubility product, reference is made to the article Metallurgical Thermochemistry, 0. Kubachewsky and E. Evans, John Wiley and Sons, Hew York (1956), pages 32-72.

It follows from the foregoing that if the amount of manganese sulfide in the steel is reduced, a lower slab reheating temperature can be used to completely dissolve these manganese sulfides. For example, a steel slab produced according to the state of the art, which is to be processed into a grain-oriented silicon steel sheet, typically contains about 0.08 % manganese and 0.025 % sulfur, resulting in a solubility product of about 0.002, calculated from the manganese content, multiplied by the sulfur content gives. To achieve the whole of this sulfide is substantially a solid solution, the slab to a temperature higher than 1316 ⁰ C, preferably 1371-1399 ° C must be heated advertising

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- ίο -

the. In the case of "minimum gel levels of manganese and sulfur" taken from the prior art, the solubility product is 0.0014, which requires a minimum temperature for reheating the slab of about 1288 ° C. As already mentioned, such high reheating temperatures have numerous disadvantages on the other hand, if the solubility product formed by the multiplication of the percentage of manganese and the percentage of sulfur is less than 0.0012 in steel, then a temperature of 1254- or less is sufficient to dissolve substantially all of the sulfide. Although such "low reheating temperatures" would indeed be extremely beneficial to the slab, such a low level of manganese sulphide cannot normally serve as an effective grain growth inhibitor if the steel has been manufactured according to conventional procedures.

According to the invention it has been found that the effectiveness of manganese sulfide as a grain growth inhibitor which is necessary to promote the orientation during the final annealing, adversely by the presence of insoluble, öxydisehen, i _m steel dispersed From distinctions such as Al ₂ O ,, SiO _2, MnO, Fe , SiO, etc., is affected.

Although the causes for this unfavorable influence are not yet completely clear, it is assumed that the causes are to be found in the very low solubility of the oxides in solid steel, the low solubility in particular occurs at the low reheating temperatures for the slab according to the invention. Additionally or instead is also the tendency of sulfur to adhere to such To deposit oxides in the form of 0χ · sulfides as the cause of the consider unfavorable influence. At the

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called oxy-sulfides are the solubility limits and the kinetic conditions less effective towards the ' Development of the preferred target orientation. because these grain oriented steels necessarily have high Silicon content, they are always in the. in a calm state, which has the consequence that such oxidation products always present to a certain extent, but according to the invention it was found that the most disturbing Oxidation products are those reoxidation products to be considered which - as will be explained below - during the pouring off have been formed.

The above-mentioned phenomenon is partly reflected in the previously mentioned US Pat. No. 3,671,337, from which it can be seen that silicon-containing inclusions are troublesome and that consequently lower manganese sulfide contents as effective grain growth inhibitors can serve if the steel is deoxidized with aluminum in amounts which are sufficient to one To avoid silicon consumption and at the same time more than 0.005% acid-soluble aluminum to form aluminum nitride to be present in the steel. The aluminum nitride is believed to complement the low manganese sulfide content, so that manganese sulfide and aluminum nitride coexist and a sufficient amount of deposition phase form, which for .Earing an optimal η grain orientation is required.

The procedure nadi der. Invention is similar to that., can be used as low levels of manganese sulfide and aluminum is added to the molten steel. Is aluminum nitride however, it is not required in the method according to the invention In contrast, in the procedure according to the

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Invention 'rather uses such procedural measures, those only to prevent insoluble reoxidation products are intended so that lower amounts of manganese sulfide serve as effective grain growth inhibitors without that additional precipitates, such as aluminum nitride, are required, with the consequence that the use of lower reheating temperatures for the slab are allowed.

According to the preferred embodiment of the invention, a Si steel charge in any refining vessel, such as a hearth furnace, a bottom-blowing oxygen converter (Q-BOP melting vessel) or in a basic oxygen melting vessel, becomes a steel with 2.5 to 3 * 5% silicon in a known manner refurbished 'about 0.03% carbon' and less than 0.015% phosphorus. It should be underlined that all data in percent relate to% by weight, unless otherwise stated. The contents of manganese and / or sulfur must, however, be kept lower than in the working methods known in the prior art, in order to achieve lower amounts of manganese sulfide in the steel before the slab is reheated. The prior art typically produces steels with 0.08 to 0.1% manganese and about 0.025% sulfur. In the cooled steel this leads to about 0.068 % manganese sulfide and a solubility product of 0.002 to 0.0025. In the process according to the invention, however, it is important that the solubility product, calculated from the percentage of manganese multiplied by the percentage of sulfur, is no longer than 0.0012, with a solubility product between 0.0007 and 0.001 being preferred. For this purpose, it is necessary to reduce the amount of either one or both reaction partners ¹ in steelmaking.

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For example, a manganese content of 0.05% and / or a sulfur content of 0.02% sufficient to result in a solubility product to get from about 0.001. The following table, which with regard to the stand The usual way of setting up the reactants during steel production is of interest in the art other optional modes of operation according to the invention.

% By weight of hangan in the permissible sulfur

Molten pool content (% by weight)

0.08 0.009 to 0.013

0.07 0.011 to 0.015

0.06 0.012 to 0.018

0.05 0.015 to 0.022

0.04 0.019 to 0.023

Reduced manganese contents can be achieved in such a process by selecting a low-manganese scrap and hot use before steelmaking, by extending the duration of the oxygen blowing in or by increasing the effectiveness or the efficiency of the manganese oxidation during steel production and / or by reducing the amount of manganese used during deoxidation of the steel bath will.

Reduced amounts of sulfur can be used in such a process through a comparable selection of the metal insert and steel production processes and / or through the use of different For desulphurisation of the molten steel before or during the casting process, the usual working methods are

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aims to be.

Although all the sulfur content ranges listed in the table above in connection with the listed manganese contents are suitable for carrying out the method according to the invention, an additional advantage can be achieved by minimizing the sulfur content and an associated certain excess of manganese. This facilitates desulfurization during the final annealing, which means that less sulfur has to be removed during the final annealing, with the result that the magnetic properties of the steel are optimally developed. For example, with a view to more economical final annealing, it is an additional advantage to produce a steel with a manganese content of about 0.07 or 0.08% and sulfur contents of about 0.011 to 0.015 % or or 0.009 to 0.013%. Such determinations of the relative manganese and sulfur contents within the content ranges compiled in the table above lead to a manganese content that is greater than required for stoichiometric considerations and consequently a highly complete consumption or degradation of the available sulfur is ensured by the formation of manganese sulfide.

After the The desired chemical composition of the hot metal is achieved has been, the steel is cut off and poured. In contrast to the working methods customary in the prior art the pouring process used in the method according to the invention must be one that causes the formation of insoluble Reoxidation products excludes or at least one Minimum restricted. To explain this point of view, let underlined that when casting conventional silicon steels the narrow casting stream has a fairly extensive surface

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"Pure molten steel section with low oxygen content possesses., which is exposed to the oxygen-containing atmosphere. This has the consequence that a considerable Reoxidation of the steel components takes place, causing the troublesome insoluble oxides are formed, as discussed above. That is, these insoluble oxides are concentrated in the ingot and the effectiveness of the manganese sulfide deposits as grain growth inhibitors adversely affect. To ensure that the small amount of Manganese sulfide is more effective in subsequent heat treatments Grain growth inhibitor is effective, the amount of insoluble seoxidation products formed during decanting must accordingly be kept to a minimum. To this end, it is obvious that when the steel passes through a oxygen-poor atmosphere is poured off, the intended results of the invention can be obtained. As a matter of fact one embodiment of the invention provides a casting of the Stahls through such an atmosphere with low oxygen content or through an inert atmosphere in order to act on them Way to minimize the insoluble reoxidation products. Apparently Pouring silicon steel through an inert atmosphere is an expensive operation that is not is applicable to the large-scale operation with high production figures.

Another novel feature of the present invention is the use of aluminum alone to prevent the To see the formation of disruptive reoxidation products, this being done without the need for an inert atmosphere. Accordingly, the preferred embodiment of the invention allows for "late" and "excessive" aluminum addition the molten steel before casting. In order to explain

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it should be underlined that in the deoxidation processes customary in the prior art, aluminum or other deoxidizing agents can be added to the tapping pan while the furnace is being tilted or immediately afterwards. With the The term "late" as used above means that the addition of aluminum for as long as reasonably possible is delayed and takes place immediately before tapping. The term "excessive" used above means that the amount of aluminum added is above the amount of aluminum normally required to quench the steel it is assumed that no further deoxidizing agents are added. At the invention According to the method, however, the steel is already due to its high silicon content and previous aluminum and manganese additives been calmed down. Thus, the late and excessive addition of aluminum has nothing to do with deoxidation or sedation of steel to do. Rather, the late and excessive aluminum addition mentioned above serves the purpose of keeping the beam of the molten steel during casting before any significant conversion between contained in the steel To protect silicon, manganese, sulfur and iron with oxygen from the atmosphere surrounding the tapping jet The late addition of aluminum serves to minimize aluminum oxidation reactions within the steel to have a sufficient amount of unreacted soluble aluminum to ensure during pouring. During the pouring process, a preferred oxidation of the im takes place Steel contained aluminum opposed to oxidation of the other oxidizable components. The products of this implementation tend to collect in the form of large viscous masses, which willingly on top of the poured-off cnra Block and therefore not within the Gußbl ^ '- Ic: dispersed, what with the normal reoxidation proaukiori

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takes place, which are formed during the pouring process.

This late and excessive addition of aluminum according to the invention is ideally driven so far that all of the aluminum added in this way is oxidized during casting and that no appreciable soluble aluminum remains in the steel block. As a result, such an excessive amount is required Aluminum addition at least about 0.068 kg of aluminum, which is to be added per ton of steel. As the soluble aluminum readily oxidized during pouring, it is difficult to set a maximum amount for such aluminum addition to name. So up to 0.235 kg of aluminum per ton of steel are without an appreciable increase in the soluble aluminum remaining in the steel has been added. That means that then if no significant amounts of aluminum or amounts of aluminum up to 0.235 kg per ton of steel immediately before casting are added, final soluble aluminum contents in the ingot of about 0.003% can be obtained. As within the scope of the invention accordingly, an addition of aluminum in the area is preferred of 0.068 to 0.235 kg per ton of steel is suggested / It should be underlined, however, that larger amounts of aluminum are also possible can be added, although this would affect the economics of the process.

After the steel has been effectively deoxidized and poured in the manner previously described, the ingot produced becomes further processed in the conventional way. This further processing includes soaking the block at about 1316 ° C and rolling it out in the heat to one Slab.

Before the slab is heated to the finished size

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is rolled, it is of course necessary to reheat the slab and, in accordance with the procedures of the art, the slab must be heated to a temperature sufficient to dissolve substantially all of the manganese sulfides in solid solution. However, since the MnS-solubility is inventively produced slabs only in the area 0.0007 to 0.0012, a slab heating temperature of 1166 to 1310 ° C and preferably of less than 1254- ⁰ C (on a solubility product of less than 0.001) sufficient. This is of course to be seen as the main advantage of the method according to the invention. The relationship between the required equilibrium solution temperature and the solubility product is shown in FIG. It has been found, however, that the minimum reheating temperatures that can be used in practice, as indicated above, are slightly above those minimum equilibrium temperatures for each solubility product shown.

The protection against reoxidation proposed according to the invention allows manganese sulfide concentrations that are considerably lower than those that have hitherto been used were deemed necessary to prevent disorderly grain growth. This protection against reoxidation also allows the manganese to sulfur ratio to be reduced to about 1.70 versus a ratio of about 3.0, which was previously deemed necessary to prevent hot cracking of silicon steel.

After the slab in the manner described in the appropriate

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To the extent that it has been reheated, it is rolled in the heat onto hot strip with finished dimensions, for which purpose conventional working methods are used in the prior art. These usually see a rolling au sheet having a thickness 1.27 to 2.54 mm in front of, before the temperature to between 95 and 7S8 ^ - is lowered ^0C. Then, the sheet is cooled by spraying water at a temperature between ⁰ C and 566 4-54- before the hot rolled sheet is coiled.

After the hot strip has been suitably pickled and cleaned, it is rolled down in the cold to the finished size, which is usually about 0.279 dim, with intermediate normalization annealing being possible if necessary. To achieve such a degree of reduction, two separate cold rolling processes with an intermediate softening annealing are required. To optimize the orientation in the finished product, it is necessary that the second cold rolling is carried out with a degree of reduction of 44 to 56 % and preferably of 50 to 52% in order to achieve a desired penultimate preferred orientation. If a finished dimension of 0.279 mm is desired for the end product, it is accordingly necessary that the steel is rolled down to a thickness of between 0.559 and 0.584 mm in the first cold rolling process, so that the second cold rolling to 0.279 hu &'with a degree of reduction of 50 to 52 ¥> takes place.

After cold rolling, the steel is made using conventional working methods subjected to a final treatment. This final treatment usually includes a decarburization annealing, which also causes primary recrystallization, and a Kastcu anneal at high temperature to produce the secondary? -

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crystallization, during which a structure with almost complete (110) [00i] orientation is developed.

It has already been mentioned above that the hot strip can be normalized before cold rolling. Such normalization processes are of course not customary in the working methods customary in the prior art. Albeit normalizing is not of primary importance in the method according to the invention, such a normalization process can be used with advantage within the scope of the invention, to optimize the magnetic properties of the finished product. Ideally, there is such a normalization from a continuous normalization anneal for a period of one minute at a temperature of at least 982 ° C before cold rolling takes place. For those who look to the first Intermediate annealing following cold rolling, a somewhat lower annealing temperature is preferred. That is, according to the invention, an intermediate annealing temperature of preferably 871 to 899 ° C is used when normalization is performed, whereas conventional procedures do not apply normalization an intermediate annealing temperature of 927 to is used.

example

A batch was melted in the basic oxygen converter or crucible, which in the form of solidified ingots had the following composition:

Carbon 0.031%

Manganese 0.055%

Phosphorus 0.006 %

Sulfur 0.020%

Silicon 2.97%

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Aluminum 0.002 % (total)

Nitrogen 0.005%.

Immediately prior to casting this steel, about 0.0078 % aluminum or about 0.0707 kg per ton of finished steel was added. Surprisingly, the final aluminum content of the solidified steels (0.002 %) was no greater than that of conventionally produced silicon steels (0.002 to 0.004%). Ingots made from such steels were soaked at about 1316 ⁰ C and rolled to 165.1 mm thick slabs. Various slabs were reheated at temperatures between 1177 and 1310 C and rolled into 2.032 mm thick sheet. The hot rolled sheets were subsequently processed into 0.279 mm thick sheet, as set forth above, wherein a first two-minute calcination at 871 ⁰ C, a rolling degree of 50 to 52% and a second five-minute decarburization annealing at 802 ⁰ C and a 7.5 hour long Kastenglühung was made at 1177 C. Then, the ^B leche accordance with ASTM Standard A 343-60 T tested. The ASTM standard mentioned relates to standards relating to magnetic properties, published by the American Standards Institute ASTM, - Philadelphia, Pennsylvania, Race Street No. 1916: In the case of sheets manufactured from slabs reheated between 1238 and 1243 ° C, the core losses determined in the experiment at 17 kilogauss were in the range of 0.686 to 0.746 watts per 0.453 kg at 60 Hertz, whereby the total of the values achieved made the sheets suitable for the production of oriented electrical steel sheets according to US material M-4. The core losses of these sheets determined at 15 kilogauss were between 0.462 and 0.525 watts per 0.453 kg at 60 Hertz. The permeabilities were 17 kilogauss

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in the range between 10 761 and 12 500 and the permeabilities 15 kilogauss ranged from 28,304 to 30,000. The permeability at an exciting field strength of 10 Oersted was determined to be around 1860 for all metal sheets.

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Claims (21)

Claims 1. Process for producing grain-oriented Si steel sheet, "in which a Si-containing slab produces this The slab is rolled in the heat to the finished size of the hot strip, the hot strip is subjected to double cold rolling with intermediate annealing subjected the cold-rolled sheet to a decarburization annealing subjected to primary recrystallization in order to achieve a final • Box annealing is subjected to secondary recrystallization to a grain-oriented fine structure, characterized in that only those amounts of manganese and sulfur are provided in the steel that result in a solubility product, calculated as the percentage of manganese multiplied by the percentage of sulfur, between 0 .0007 and 0.0012 lead to the fact that the steel is poured under conditions which reduce the oxidation of steel components in the cast beam surface to insoluble oxides distributed throughout the steel to a minimum, so that the slab before it is rolled out in the heat to the finished size of the hot strip a temperature lying between 1166 and 1310 ⁰ C is heated and that the sheet metal is rolled out during the second cold rolling with a degree of rolling of 44 to 56%. 2. The method according to claim 1, characterized in that that the steel is poured off by an inert atmosphere. 509849/0760 3. The method according to claim 1, characterized in that that the steel is cast immediately after adding at least 0.068 kg of aluminum per ton of steel, however, no greater amount of aluminum is added to the steel than that which is about 0.006% soluble Aluminum in the solidified steel leads. 4. A method for producing grain-oriented Si steel sheet, in which a steel containing Si is produced, this steel is poured into a mold for the purpose of producing a steel block, the cast block is rolled into a slab in the heat, the slab in the heat to the finished size of hot strip rolled out, the hot strip is subjected to double cold rolling with intermediate annealing, the cold rolled sheet is subjected to a decarburization annealing to achieve primary recrystallization and the steel sheet is finally subjected to box annealing to achieve a secondary recrystallization to a grain-oriented fine structure, characterized in that only such amounts of manganese are provided in steel, which lead to a solubility product between 0.0007 and 0.0012 formed from the percentage of manganese multiplied by the percentage of sulfur, that an excess amount of aluminum is added at a late point in time before casting m steel is added that the steel is ^{heated to a temperature of 1166 to 1310 0} C in the heat to hot strip finished size and that the sheet is rolled out during the second cold rolling with a degree of rolling of 44 to 56%. 5. The method according to claim 4, characterized in that that the aluminum meets the steel immediately before 509843/0760 pour is added. 6. The method according to claim 4, characterized in that that the excess amount of aluminum is such. Amount of aluminum that is larger than that normally to completely deoxidize a given amount of steel "amount required. 7- method according to claim 4, characterized in that that at least about 0.068 kg of aluminum per ton of steel are added to the steel. 8. The method according to claim 4, characterized in that that 0.068 to 0.235 kg of aluminum was added per ton of steel will. 9. The method according to claim 4, characterized in that that manganese and sulfur are only provided in the steel in such amounts that one out of the percentage Proportion of manganese, multiplied by the percentage of sulfur formed solubility product of 0.0007 lead to 0.0010. - 10. The method according to claim 4, characterized in that about 0.08% manganese and about 0.009 to 0.013 % sulfur are provided in the steel. 11. The method according to claim 4, characterized in that that about 0.07% manganese and about 0.011 to 0.015% sulfur are provided in the steel. 12. The method according to claim 4, characterized in that that the steel slab before it is rolled out in the Υί ?. 509849/0760 is heated to a temperature of 1233 "to 131O ^{0 C to a finished size of hot strip.} 13. The method according to claim 91, characterized in that the steel slab is ^{heated to a temperature of 12-18 to 125 2} I- ⁰ C in the heat to finished hot strip dimensions before it is rolled out. 14. The method according to claim 4-, characterized in that the steel is deformed during the second Kaltwalzumg with a rolling degree of 50 to 52%. 15 · The method of claim 4, characterized in that the rolled-in of the heat to the hot strip final size steel is normalized before cold rolling for about 1 minute at a temperature of at least 982 ⁰ G, and in that the intermediate annealing at a temperature of 871 to 899 ⁰ C is carried out. 16. A method for producing grain-oriented Si steel sheet, in which a Si-containing steel is produced, this steel is poured into a mold in order to obtain a steel ingot, the ingot is rolled in the heat into a slab, the slab in the heat to the finished size of hot strip rolled out, the rolled sheet is subjected to double cold rolling with ZwJS3henglühung ', the cold rolled sheet is subjected to a decarburization annealing for the purpose of primary recrystallization and the steel sheet is finally subjected to a box annealing for the purpose of producing a secondary recrystallization to a grain-oriented fine structure. 07 to 0.08 % e * ngan and sufficient sulfur in the steel are provided to. a. nit ο en multiply from the percentage of manganese 509849/0760 percentage of sulfur formed solubility product between 0.0007 and 0.0.01 to achieve that immediately before the casting of the steel at least 0.068 kg of aluminum per ton of steel, but no greater amount of aluminum than that which is about 0.006% soluble Aluminum in the solidified steel ■ is added, that the slab gate is ^{heated to its rolling in the heat to the finished size of hot strip to a temperature lying between 1166 and 131O 0} C and that the sheet metal during the second cold rolling with a degree of rolling of 44 to 56 % is rolled out. 17. The method according to claim 16, characterized in that the steel has a manganese content of about 0.07 to 0.08% and a sufficient sulfur content to achieve a solubility product of 0.0007 to 0.001 that the slab is in the Heat is heated to the finished size at a temperature of 1238 to 1254 ⁰ C and that the steel is subjected to a 50 to 52% reduction in cross section during the second cold rolling. 18. The method according to claim 17, characterized in that the steel is ^{normalized for about 1 minute at a temperature of at least 982 0} C before cold rolling and that the first cold rolling. subsequent intermediate annealing will lead. annealing at a temperature of 871 to 899 ° C 19 · A method for producing grain-oriented Si steel sheet, characterized in that a batch of molten steel with 2.5 to 3.5% silicon, 0.04 to 0.08 % manganese and a sulfur content sufficient to achieve one of the percentages Manganese content multi- 509849/0760 multiplied by the percentage of sulfur formed Solubility product of 0.0007 "to 0.0012 is that at least about 0.068 kg of aluminum per ton of steel are added to the steel, but no greater Amount of aluminum is added as such that leads to about 0.006% soluble aluminum in the solidified steel, that the molten steel is poured immediately after the aluminum addition in molds to at least one To produce ingot that the ingot is rolled out in the heat to form a slab and the slab to a temperature of Heated from 1166 to 1310 C and rolled to the finished size of hot strip is, and that the hot strip with the finished size is twice Is subjected to cold rolling with intermediate annealing, the second cold rolling with a rolling degree of 44 to 56% to a finished dimension of 0.254 to 0.381 mm thickness, whereupon the cold-rolled sheet in a decarburizing The atmosphere is annealed for the purpose of decarburization of the steel and to achieve a primary recrystallization and a final one Box annealing is subjected to secondary recrystallization to a preferred orientation for the purpose of achieving secondary recrystallization. 20. The method according to claim 19 ■> characterized in that the molten steel contains about 0.07 "to 0.08% manganese and a sufficient amount of sulfur to achieve a solubility product of 0.0007 to 0.001 that the steel slab before it is rolled out is heated to a temperature of 1238 to 1254 ⁰ C to the finished size of hot strip and that the steel is subjected to a 50 to 52% reduction in cross section during the second cold rolling. 21. The method according to claim 20, characterized in that g e "k e η η ζ e i c h- net that the steel before cold rolling about 1 minute I ^:. · ^ 509849/0760 "normalized at a temperature of at least 982 ° C and that the one following the first cold rolling Intermediate annealing at a temperature of 871 "to 899 C is performed. 509849/0760 Blank page