DE1920968A1 - Process for the heat treatment of magnetic sheets for high magnetic induction - Google Patents

Description

Dr. F. Zumsiein - Dr. E. Assmann

Dr. R. Kocnlarborgör
Dipl. P; W ₅ . P ₁ . H.ijvfc _except

2 / H Munich 2, Bräuhausstrafje 4 / ill

Yawata Iron & Steel Co., Ltd., Lokyo / Japan

Process for the heat treatment of magnetic sheets for high magnetic induction

The invention "relates to a method for producing simply oriented Magnetic sheets made of steel with an easy to magnetize lying in the rolling direction of the sheet <100> axis.

Single-oriented steel sheets as soft magnetic material! - en are used in most cases for the iron cores of trans, formators and other electrical devices used ·. The imag- "· ' The genetic properties of these steel sheets must be favorable, i.e. they must be excitable, and the iron or core. : losses should be low. . · .- '· ■ _ *.

In connection with the invention the in the iron core durcii, the magnetic field strength H ^ ₀ (in Oersted) generated magnetic. Induction B ^ ₀ (in Gauss) as the value for the excitation characteristics and the W 15/50 iron losses (in watts / kg) at 50 Hertz and an alternating current induction of 15,000 Gauss as the value for the iron losses, i.e. the energy losses in /. Iron core determines for the pail that this iron core with the; mentioned alternating current induction is applied. _ ■ i '

In recent times it is becoming more and more important to size electrical Devices, such as! Transformers, are shrinking more and more,

what the *. ^j

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ORIGINAL INSPECTED ;, _: .

Requirement for a reduction in the core weight results. In order to be able to reduce the iron weight of electrical appliances, sheet steel must generally be used which can be subjected to high magnetic induction or in which the heat resistance is high. For this purpose, a steel sheet with favorable magnetizing properties is required, ie a sheet. whose magnetization characteristic is characterized by a high B value (magnetic induction with a field strength of Oersted) and, in particular, by a high saturation value B. It should be noted that the use of a steel sheet with high magnetic induction generally leads to higher iron losses. In comparison with a material with a low B _Q value, however, a steel sheet with a high B _O value results in far lower iron losses in the region of high magnetic induction, and the iron losses rise more slowly with increasing magnetic induction.

In summary it can be stated that the arithmetical magnetic flux density, which is absolutely necessary with increasing power of electrical devices, can only then be increased can when magnetic sheets come on the market that allow a very high magnetic induction.

The aim of the invention is therefore to develop magnetic sheets which meet the requirements mentioned above. By means of the inventive method, it is possible to produce magnetic sheets, the conventional single-oriented Siliciumstahl-, sheets with respect to their B. _Q -value in the rolling direction are markedly superior to, that steel sheets, the magnetic induction of at least 18 500 gauss up to 20 100 gauss From this it can be clearly seen that the magnetic induction that can be applied to the steel sheets according to the invention is significantly greater than all previously known maximum values, that is to say, for example, _Q =

18 690 Gauss according to US Pat. No. 2,867,557 and B ₁₀ "

19,100 to 18,000 Gauss according to U.S. Patent 3,287-183.

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The invention further discloses a new fact to be described below with regard to the production of simply oriented magnetic sheets which, in order to improve the value B, have a low or no Si content. B is a physical property which is determined by the chemical composition of a steel alloy and which cannot be influenced by the treatment conditions. In particular, the Si content has a great influence on the B value. For example, if the Si content is 0%, an induction of 21,600 Gauss can be achieved, while this value is about 21,300 Gauss for 1% Si, about 20,800 Gauss for 2% Si and about 20,800 Gauss for 3% Si 20 300 Gaussian drops. That is, the lower the Si content, the higher the B value. In conventional Si steel sheets, however, the decrease in resistance and the deterioration in iron loss values are due to their low Si content. Apart from that, it has not been possible to date to manufacture steel sheets with crystals of the so-called] n ° j <100> orientation on an industrial scale. It was therefore not at all possible to produce simply-oriented steel sheets whose high B value could have been exploited. The invention made it possible, even with a low Si content, to produce ideal, single-oriented magnetic sheets for high magnetic inductions, ie with a high B _Q value and, moreover, with a high B value, in which over a wide Si— Range of, for example, 0 to 4% secondary recrystallization grains of the very well selected IIIOv <(100> orientation).

US Pat. No. 2,113,537 discloses a method for producing an oriented silicon steel sheet, in which the silicon steel material containing 3.5% Si, 0.1% Mn and 0.1% Al is subjected to the following production process, ie the silicon steel hot rolled and then annealed at 1000 ⁰ C for 1 hour and subsequently quenched, after which a cold rolling is carried out in several stages, bringing the steel sheet to the final dimensions and is finally hot rolled at 45O ° C.

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US Pat. No. 3,151,005 also shows a method to improve iron losses by tempering a hot rolled one Silicon steel sheet with at least 0.01% carbon content at 795 to 960 C, thereby causing a solid solution of the C content, whereupon the steel sheet quenched from this temperature to less than 54O ° C.

In the treatment method according to the invention, referring to a manufacturing method for single-oriented silicon steel sheets for high magnetic inductions, in which a normal steel or silicon steel refers to C and Al as un-.

- stay, ......

Permissible elements / is produced by known steel production, melting and casting processes which are used as normal industrial techniques, the steel thus obtained is hot-rolled and then subjected to a tempering and cold-rolling process once or several times in order to bring the sheet metal to its final dimensions, whereupon the product obtained is decarburized and then subjected to a final tempering process in order to produce the secondary recrystallization grains with -s10J- <.100 / "- orientation in the steel material. The invention is particularly characterized in that the final cold rolling process in one of the Si -Content-dependent reduction ratio of 65 to 95% is carried out, and that an intermediate annealing, preferably an annealing immediately before the final cold rolling, takes place in such a temperature range that the ^ f conversion occurs at least / part of the steel material, ie in one Range from 750 to 1200 ^D C, followed by a quenching out of this A temperature range takes place in which the conversion of -Y-'ZU oo has been completed to a temperature below this range, ie, depending on the Si content, to a temperature below the range from 750 to 95O ° C., so that AlN- is more preferred Size in which steel sheet is deposited ". As a result, after the final tempering or annealing, values of the magnetic induction B _Q in the rolling direction that were previously never attainable can be generated, ie values that range from at least 18,500 to a maximum value of 20,100 Gauss «

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It was previously disclosed in U.S. Patent 3,287,183 that a single-oriented silicon steel sheet for high magnetic inductions from a silicon steel bar with 2.5 to 4% Si content can be obtained using C and Al as the starting material contains. By the present invention, however, the disclosed method has been successfully completed to the extent that Products with significantly improved properties were created, and that at the same time as the production of simple-oriented ones Silicon steel sheets for high magnetic induction made from sheet steel with little or no silicon content with previously unknown properties.

The object of the invention is a method for producing a single-oriented silicon steel sheet for high magnetic fields Inductions. A steel sheet with little or no silicon content should be used. It's supposed to be one for making simply-oriented silicon steel sheets given the most suitable chemical composition v / ground to high to achieve magnetic inductions, whereby - as mentioned - no or only a low silicon content should be provided.

The invention is explained in more detail below with reference to the drawings, for example.

Fig. 1 shows the excitation properties of the invention Products compared to commercially available products.

Fig. 2 illustrates the iron losses of products according to the invention compared to commercially available products of a comparable type.

Fig. 3 illustrates the relationship between the values of C and acid-soluble Al in products of the invention and the excitation properties.

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Fig. 4 illustrates the relationships with respect to the cooling rate after annealing according to the invention and the excitation properties.

The details of the invention will now be explained in more detail below. ·

The ordinary steel or silicon steel used as the raw material is used, is made according to a known steel production process, for example in the Siemens-Martin furnace, in the electric furnace or converter, manufactured or by a known melting process, for example in the high-frequency electric furnace or in a vacuum melting furnace, melted and cast into a slab using any casting method, which then solidifies. A plate-shaped casting blank can also be produced, which has recently been widely used continuous casting process is produced. Usually is poured in an atmospheric environment, but can can also be worked under vacuum or an inert gas atmosphere.

Although - as described above - the starting material for the process according to the invention can be produced by any steelmaking, melting and casting process, however, the composition of the material must meet the following conditions regardless of those for production of the same manufacturing, melting and casting processes used:

Content of C less than 0.085% Si 0 to 4%
Al 0.010 to 0.065%.

Al is understood to mean acid-soluble aluminum, but that is hereinafter referred to as Al for the sake of simplicity will. The rest is iron and unavoidable impurities .. 'It is necessary that the C-content in the · above-mentioned'

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material is present in an amount sufficient to achieve a -conversion at least in accordance with the Si content in a part of the steel. It has been found in tests that 0.025% C must be present in a slab with an Si content of at least 3%, while approximately 0.005% C can be present with an Si content of 0%. With regard to the added elements, the following explanations should apply. In general, a selected or preferred direction arises in the production of a single-oriented magnetic sheet, since secondary recrystallization occurs during the final annealing treatment in the {11 ° j <100> direction. However, the precipitates generated by small amounts of additional elements, such as nitride, sulfide or oxide, play an important role. It is believed that this only finely disperses and deposits the precipitates, so that normal grain growth can be inhibited and secondary recrystallization can be accelerated. However, it has been found within the scope of the invention that the deposit has a further effect besides the one mentioned above. Part of it, which is deposited in a specific directional relationship with the matrix, also results in the crystal grains growing only selectively in a "specific direction-p - thereby precisely regulating the direction of the secondary recrystallized grains. This results in a product , which has an excellent B _O value. AlN, which produces a satisfactory effect by adding Al at the time of the final annealing treatment according to the invention, gives the properties mentioned the deposits formed by the addition of other elements show no such ability, but only appear to have an inhibiting effect on the growth of the crystal grain structure. However, this growth-inhibiting effect of ordinary deposits is also an important factor for causing the secondary recrystallization. Therefore, the presence Deposits n constituent elements are permissible as long as they support the formation of AlN

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do not hinder. For example, as from the manufacture of single-oriented silicon steel sheets. knows, S, Se and similar be present in a proportion of -w.eni.ger 'than a maximum of 0.1%. Furthermore, as far as known. Te is less than 0.20 % . However, in the case of the present invention, special care must be taken with such additional elements, since they tend to form deposits such as carbide. Taking into account the N contained in steel, Zr and Ti, which have a stronger affinity for N than Al, should be added . It should be noted that, as described later, a certain amount of AlW can be deposited after annealing. B, Ta, Nb, V, Cr, Mn, W and Mo have a weaker affinity than Al and can therefore be added in suitable amounts known in the production of singly-oriented silicon sheets. The maximum permissible amounts of these deposit-forming elements be at V, Mn and Mo 1%, wherein W and 0.5% at B, Zr, Ti, Mb, Ta and GrO ₁ I% .. However, there is a total of only about Examples. Additions of these deposit-forming elements with the aim of accelerating the secondary recrystallization in a range that does not hinder the formation of AlN, the basis of the invention, are within the scope of the invention.

The following explains the reasons why the block together
settlement. of the raw casting / according to the invention is prescribed «A silicon steel slab with a content of 1.8% Si and with variable contents of C and Al was hot-rolled to a steel sheet about 2 mm thick. The sheet metal was first annealed in an Np atmosphere at 1050 ^° C. for 2 minutes and then sprayed with finely atomized water droplets. Then, the steel sheet was cooled to room temperature in about 50 seconds, whereupon it was cold-rolled into a steel sheet of 0.35 mm in thickness. The thus cold-rolled steel sheet was decarburized at 800 ° C and then box annealed for 15 hours at 1050 ⁰ C. Fig. 3 shows the relationship between the magnetic induction B _Q

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of the product thus obtained and the content of C and Al in the slab. The figure shows that the product desired according to the invention is subjected to a magnetic induction B of more than 18,500 Gauss in the rolling direction
could if the C and Al contents corresponded to the following values:

C content 0.015 to 0.085%

Al content 0.010 to 0.065%.

Furthermore, it was found from the tests in which the Si content was changed from about 0 to 1 and 3 % that the Al content necessary for obtaining the product for a magnetic induction B _ of more than 18,500 Gauss for all different
Si content can be the same, while the C content should be less than 0.085% or in the range from 0.025 to 0.085%. This corresponds to the C content required for the ^ transformation in at least part of the steel sheet during annealing and before the final cold rolling, as will be explained in more detail below.

The Si content is chosen to be less than 4%. Because the invention aims to improve the B-iq and B characteristics the lower limit is not defined in more detail.

The process for forming the desired AlN, which forms the basis of the invention, will now be described. Already in US patent specification 3__ 287 183 is. .explains. that ^N .das_Ab = __. separate ^{from A1N with} such a deposit size
'What is required is that secondary recrystallization grains
be formed in the steel prior to final cold rolling. One of the operating conditions for the process according to the invention should therefore be the annealing immediately preceding the final cold rolling in a temperature range of
950 to 1200 ⁰ C can be carried out for 30 seconds to 30 minutes when the Si content is in the range from 2.5 to
3.5%. In this case, the C content in the steel before this annealing should be in the range of 0.020 to 0.080%. To that

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The object of the invention / the production of a single-oriented silicon steel sheet with a low Si content, some changes in the operating conditions depending on the various contents are desirable. For example, with an Si content of 1 to 2.5 %, the annealing should be carried out in a temperature range of 850 to 1200 ° C., while with an Si content of less than 1% a temperature range of 750 to 1200 ° C. should be selected. However, the above-mentioned annealing conditions are also essentially required in connection with the invention, although, as mentioned, the temperature range varies depending on the Si content. For each Si content, the annealing time can be in the range from 30 seconds to 30 minutes. In each case, the annealing time and the temperature range are predetermined so that, depending on the Si content, a Tf transformation can take place in at least part of the steel sheet. Once the annealing prior to the final cold rolling has been completed under the operating conditions mentioned above, the steel is cooled to a desired temperature and then subjected to an obligatory quenching by suitable artificial means.

Figure 4 illustrates the relationship between the magnetic induction B _{0 of} a product and the cooling rate for the case that the product is made from a silicon steel slab with 2.2% Si content, 0.045% C content and 0.025% Al content in the following stages The steel slab is pre-rolled and hot-rolled to form a hot-rolled steel sheet of 2.3 mm thickness, then the hot-rolled steel sheet is heated in a nitrogen atmosphere for 2 minutes at a temperature shown in FIG.

the annealed sheet steel /

annealed temperature illustrated and then determined Cooling rate gradually cooled to 850 ° C. ' The steel sheet is then cooled to temperatures below 85O ° C. with various cooling speeds, such as is shown by / different cooling curves in Figure 4. The following parameters could be determined from this picture, whereby,

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if the tempering temperature 800 or 700 ⁰ C was carried out cooling from this temperature along the corresponding cooling curves. It was found that the higher the annealing temperature, the better the value B ^, although there was a maximum for B and that the B _Q value was also the better, the greater the cooling rate in the temperature range below 850 ° C . If the annealing temperature is above 85O ⁰ C ₁ , the cooling from this temperature to 850 C can take place at any desired cooling rate. If the annealing temperature is over 1200 ° C., secondary recrystallization does not occur in the final annealing, while on the other hand, if the annealing temperature is lower than 800 or 700 ° C., the quenching treatment does not affect the * B ^ q value. A lower absolute value for-B.- then results, which is below 18,500 Gauss. In both of these cases, the product desired in the present invention cannot be obtained. From tests with test pieces with different silicon content could be with respect to the AlN deposition durch.Glühen before the final cold rolling draw the following conclusions:

The C content should be adjusted so that it is below 0.080%, so that in at least a part of the steel sheet, taking into account the Si content, a ^ -conversion when performing the annealing treatment before the final cold rolling can be done. It results in the following compilation:

for 0 to 1% Si less than 0.80% -C (a cast steel block or

a raw slab with less than 0.085% C),

for 1 to 2.5 % Si 0.010% to 0.080% C (a steel slab

from 0.015% to 0.0-85 % C),

for "2.5 to 4, ο% Si 0.020% to 0.080% C (a steel slab

from 0.025% to 0.085 % C). .

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The carbon content in the cast steel block or in the steel slab is 0.005 % higher than before the annealing before the final cold rolling, since the decarburized amount must be taken into account in the usual hot rolling. In essence, the C content in the steel sheet is important when performing the annealing treatment before the final cold rolling.

In the event that the final thickness of the sheet is reduced by a one-off Cold rolling process is produced, the C content of the steel sheet at the time of performing annealing treatment can be easily made can be set to be in the above specified range when the annealing treatment after hot rolling is carried out. However, the cold rolling is done in a multistage If the operation is carried out as mentioned below, then it must be taken into account that a decarburization has taken place in the meantime can occur because several intermediate annealing treatments are carried out. In this case too, the C content of the Steel sheet at the time of carrying out the annealing treatment before the final cold rolling can be regulated so that it is in the above-mentioned prescribed range.

The annealing temperature in the range between 750 ° C to 1200 ° C, in which a ^ -conversion with respect to the Si content occurs. The following can be put together for this purpose;

750 to 1200 ⁰ C for less than 1% Si. ·

850 to 1200 ° C for 1 % to 2.5% Si
960 to 1200 ⁰ C for 2.5 % to 4.0% Si.

The annealing treatment time in this temperature range is 30 seconds to 30 "minutes.

If this annealing treatment exceeds 30 minutes, wah occurs At the end of the annealing, the crystal grains grow, and the secondary recrystallization grains are formed at the final Annealing treatment becomes imperfect. Therefore is to

long glow not favorable.

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Furthermore, since this annealing treatment is generally carried out continuously, it is an annealing state beyond 30 minutes industrially disadvantageous. On the other hand, with an annealing treatment of less than 30 seconds, according to the invention desired effect cannot be achieved.

Once the above annealing treatment of the steel strip or sheet has been completed, it is subjected to cooling, which, however, is carried out at any cooling rate in a temperature range in which the ψ formed during this annealing treatment is converted into cO, i.e. in a range of ' 75O ⁰ C to 1200 850 to 1200 ° C or 95O ° C to 1200 ° C, entsprechend'dem Si content.

Thereupon, the steel sheet in which the oo-conversion has been performed by this cooling, from the temperature range of from 75O ° C to 1200 ⁰ C, 85O ° C to 1200 ° C or 95O ° C to 1200 ⁰ C in accordance with the Si content Quenched to a temperature below 400 ⁰ C by using appropriate artificial facilities. The cooling time ranges from 2 seconds to 200 seconds, and it is desirable to cool in a shorter time when the Si content is high. In general, the higher the di, e cooling rate, the better the B value, regardless of the Si content. Tests have shown, however, that if the cooling rate is less than 2 seconds, the generation of secondary recrystallization grains by the final annealing is complete, but the B "Q value is deteriorated. Furthermore, different cooling curves are conceivable with regard to the cooling from the temperature range from 750 to 950 C down to 400 C, but in all these cases the effect according to the invention can be achieved if the cooling rate at any given moment is greater than the following average cooling rate. . . . -. "

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750 ° C to 400 ° C / 2OO s (below 1% Si ") ^

85O ° C to 4OO ° C / 2OO s (1% to 2.5% Si) 95O ° C to 400 ° C / 200 s (2.5% to 3.5% Si).

According to the invention, there is no particular limitation with regard to the cooling from 400 ° C. to a temperature below this. It goes without saying that it is within the scope of the present invention to use the cooling rate according to the invention. - -

However, even if the cooling rate is changed below 400 ° C, substantially no influence thereof on the B- _O value of the product is noticed. In the practical industrial process, however, it is a matter of course that a steel sheet is always cooled to near room temperature because of descaling and cold rolling of the steel sheet after the annealing treatment. Therefore, when forced cooling is carried out using any of the above-mentioned means, it is usual that the steel sheet is cooled from the temperature range of 750 to 950 C - corresponding to the Si content, to almost room temperature along a continuous curve. Since quenching from the initial temperature of the quenching process, such as from 750 to 95O ° C down to 400 ° C, has particularly sweeping effects with regard to promoting the deposition of the desired AlN and consequently an improvement in the B value of the product, according to the invention the temperature limits are, as mentioned above.

An unavoidable condition is that at least an amount of 0.0005% AlN (N as AlN) is deposited in the steel sheet should be after the annealing treatment and cooling are accomplished.

The annealing treatment atmosphere is created with the deposition of AlN, those for secondary recrystallization, as already described, is necessary, related. Usually contains the raw steel slab that is placed in a Siemens-Martin furnace

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receives more than 0.0040% N as it is, which is for the deposition of 0.0005% AlN (N as AlN) is sufficient. So as long as that no significant denitrification occurs, the annealing treatment can satraosphere be a reducing or neutral atmosphere, for example of H, Ar, a gaseous mixture consist of it or of air. In the case where, however the raw slab is produced by vacuum melting or the like, the M content is so small that it is necessary to add nitrogen to the annealing treatment. The procedure for adding nitrogen is not prescribed, but it is in the case of the present invention, it is recommended to carry out the annealing treatment in a neutral or reducing gas, which contains at least 10% by volume of N ".

For a separation in which secondary 'recrystallization grains can grow selectively, which have the very regular, but not perfect orientation due to the final annealing treatment, it was found according to the invention that only AlN is present as a deposit, as already mentioned at the beginning. The difficulty with the present invention resides precisely in causing the AlN to be deposited in an appropriate size in the steel sheet before it is subjected to the final, heavy cold rolling. Further, if the AlN is deposited and the grain size and distribution is controlled, the composition of the steel sheet (C, Si and Al) has a close mutual relationship with the temperature and time of the annealing treatment and the cooling rate by the medium for the conversion of j ' to &>.

According to the invention, the cold rolling is carried out one or more times, and the cold rolling step can be carried out with one reduction from 65 to 95% with respect to the Si content, so that the reduction can be higher, the higher the Si content. By combining the annealing for the AlN deposition before the final strong cold rolling and final strong cold rolling, it is possible to achieve a product of which

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B ₁₀ value is more than 18,500 Gauss.

Intermediate annealing, which is carried out between the stages of the multi-stage cold rolling process, can be carried out at a temperature and for a time sufficient to form the cold rolling structure as the primary recrystallization structure, which is not prescribed above annealing for AlN deposition as Zwischeng air treatment to be used. According to the invention is determined by de strength of hot-rolled sheet and the above-described reduction of the final cold rolling the number of cold rolling steps. from the industrial face .- however point out is the hot rolled sheet is usually 1 , 5 to 7 mm thick.

The steel sheet with the sheet thickness of the product after the final Cold rolling then undergoes a decarburization annealing treatment subject. This annealing treatment is intended to create the cold rolling structure bring into a primary recrystallized structure and at the same time remove C, which in the case of the development of secondary recrystallized grains in the illOt < 100) · direction is disadvantageous in the final annealing treatment. Any known Procedures are used.

The final annealing treatment should be at such a temperature and at such a time that the secondary recrystallization grains are in the j100 ^ lOO ^ direction can develop well. Is preferred when the secondary Recrystallization grains in a temperature range in which no '/' conversion with respect to the Si content is produced will, and develop at a temperature as high as industrial is possible because generating ^ "conversion does the secondary recrystallization grains once obtained in the

J 110 | <100> direction changes again. That it is a different direction to have. If the Si content is less than 1%, the annealing should be at 95O ° C. or usually at a lower temperature Temperature. However, the higher the Si

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- 17 content, the higher the temperature can be.

If the Si content is more than 2 %, a temperature higher than 100 ° C. is possible. On the other hand, no secondary recrystallization occurs below 800 ° C. If the temperature is not high, a product with an excellent core loss value cannot be obtained. Therefore, when the Si content is low, the B - characteristic is excellent, but the core loss is inferior to that when the Si content is high. An annealing treatment of more than 1 hour is sufficient for the generation of secondary recrystallization grains, but it is more than 5 hours to obtain a product with a low core loss value with a high Si content. Regardless of whether the atmosphere is neutral, reducing or so weakly oxidizing that the steel sheet is not noticeably oxidized, a product with a B value of more than 18,500 Gauss can be achieved, which is the aim of the invention. However, in order to achieve a low core loss value with a high Si content, it is preferred to carry out the annealing treatment in H_. However, the description of such a time and atmosphere is not part of the essence of the present invention.

The present invention is illustrated by the following examples further explained.

example 1

An Al killed steel ingot containing 0.050% C and 0.041% Al is rough rolled and hot rolled to obtain a hot rolled steel sheet 2.2 mm thick. After the steel sheet in N _? was annealed at 1000 ⁰ C for 2 minutes, is

ο has it cooled in warm water that has a temperature of 100 C /. The Abkühlgoschwindigkeit is about 10 seconds for the temperature drop of 1000 ⁰ C to 75O ° C and about 25 seconds d £ n drop of 75O ° C to 100 ⁰ C. The AlN content after the annealing treatment betragh 0.004 5% (N? as AlN). After descaling, the sheet is cold rolled at a reduction of 77.3%, whereby

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a sheet thickness of 0.50 mm is achieved. The cold-rolled sheet 'is then at 750 ° C for 5 hours according to the open-roll system decarburized and then finally in H at 870 C for 20 hours long annealed.

The product has the following excitation properties:

B ₁₀ = 19 950 Gauss W _{15 / 5O} = 3.60 W / kg.

Example 2

A raw cast ingot or slab made of silicon steel containing 0.32% C, 1.05% Si and 0.036% Al is hot-rolled, so that a hot-rolled steel sheet 2.2 mm thick is obtained. The C content in the hot-rolled steel sheet is 0.030 %. A 2-minute annealing of the steel sheet in N_ at 1050 ⁰ C, it is cooled by spraying weak N "gas on the two surfaces of the steel sheet. The cooling rate is 13 seconds for a drop in temperature from 1050 ° C to 85O ° C and about 70 seconds for the drop of 85O ° C to 400 ⁰ C. The AlN content after this cooling treatment is 0.0062% (N as AlN). After descaling, the steel sheet is cold-rolled at a reduction of 84.1%, so that a cold-rolled steel sheet of 0.35 ram thickness is obtained. A 3-minute decarburizing the "cold-rolled sheet in wet H ₂ at 800 ⁰ C it is finally annealed for 10 hours in _H2 at 95O ° C.

The magnetic properties in the direction of rolling of the product are, as shown in Fig. 1 B,

B ₁₀ = 19 700 Gauss ^W 15 / 5O ^{= 1} » ^{85 W / k} 9 ·

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Example 3

A silicon steel sheet containing 0.043% C, 2.10% Si and Contains 0.036% Al, is rough-rolled and v / arm-rolled, so that a hot-rolled steel sheet of 3 mm thickness is obtained. Of the C content of the hot rolled sheet is 0.041%, which indicates that only a slight decarburization was effected. First

the hot-rolled steel sheet is cold-rolled at a reduction of 30% so that a sheet thickness of 2.1 mm is obtained. Then, it is glühbehahdelt in N at 1100 ⁰ C for 2 minutes and then cooled · by inflating an air-steam beam to the sheet. The cooling rate is about 18 seconds for a temperature drop für.1100 ⁰ C to 85O ° C and about 2 7 seconds for a drop from 850 C to 400 C. The AlN content after this annealing treatment is 0.0055% (N as AlN) . Thereafter, the steel sheet is cold-rolled at a reduction of 83.3% , so that a cold-rolled steel sheet 0.35 mm thick is obtained. After the cold-rolled steel sheet has been decarburized for 3 minutes in wet H_ at 800 ° C., it is annealed at 1200 ° C. for 20 hours. The magnetic properties in the rolling direction of the product are as shown in Fig. C:

B ₁₀ = 19 570 Gauss

W _15/5 "1.15 W / kg.

Example 4 - ■

A raw slab made of silicon steel containing 0.045% C, 2.05% Si and 0.020% Al is rough-rolled and hot-rolled so that a hot-rolled steel sheet of 2.3 mm thick is obtained. The C content of the hot-rolled steel sheet is 0.041%. To annealing the hot-rolled steel sheet for 2 minutes in N at 1050 ° C it is made by gently inflating

p cooled down on the steel sheet. The cooling rate is essentially the same as in Example 2, and the AlN content after this annealing treatment is 0.0032% (N as AlN). Then the steel sheet is at a reduction of 84.8 %

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■ cold-rolled, so that you get a cold-rolled sheet of 0.35 mm Maintains strength. The cold-rolled steel sheet is then decarburized in a wet H. at 800 ° C. for 3 minutes and then finally annealed at 1200 ° C for 20 hours. The magnetic properties are in the rolling direction of the product

B ₁₀ = 18,800 Gauss

The B value of this example is lower than that of example 3, which is believed to be the lower amount of Al of this example is attributable.

Example 5

A raw slab made of silicon steel containing 0.043 % C, 2.96 % Si, 0.029% Al, 0.10% Mn and 0.029 % S is rough-rolled and hot-rolled so that a hot-rolled steel sheet 2.8 mm thick is obtained. The C content after hot rolling is 0.040%. After the hot-rolled steel strip _{has been annealed continuously in N 2} at 1150 ° C for 2 minutes, it is subjected to slow cooling down to 95O ° C in the cooling zone of a furnace, followed by quenching by spraying with high pressure water. The cooling rate is about 20 seconds for the temperature drop of 1150 C * to 95O ° C and about 9 seconds for the drop of 95O ° C to 20 ⁰ C. The AlN content after this annealing treatment is 0.0040% (N as AlN) . After descaling, the steel sheet is cold-rolled with a reduction of 87.5% so that the sheet thickness has the final dimension of 0.35 mm. After the cold rolled steel sheet

^l 2

Was for 3 minutes continuously decarburized in wet H at 85O ° C, it is finally annealed for 15 hours in H at 1200 ⁰ C. The excitation properties in the rolling direction of the product are as shown in Fig. 1D:

B ₁₀ = 19 810 Gauss ^W 15 / 5O ⁼ 0.90 W / kg,

10 9 8 17/0673

_ ₂₁ _ 19 * 0968

what an excellent orientation and an outstanding Represents core loss value. Fig. 2 shows the core loss characteristics of this example, compared with those of a known commercial product shown in Fig. 2E.

Example 6

A raw slab of silicon steel containing 0.050% C, 3.15 % Si, 0.035% S and 0.021% Al and manufactured in a Siemens-Martin furnace is rough-rolled and hot-rolled so that a hot-rolled steel sheet of 3.0 mm thickness. After the hot-rolled steel sheet was kept at 1,050 ° C. for 1. minute in a continuous annealing furnace with N "atmosphere, it is subjected to forced cooling by using an Np gas inflator installed at the furnace opening. After descaling, the steel is cold-rolled with a reduction of 51%, so that a cold-rolled sheet with an intermediate dimension of 1.4–7 mm is obtained. The cold-rolled steel sheet is then annealed at 800 ° C. for 1 minute to effect primary recrystallization, and then subjected to strong final cold-rolling at a reduction of 84.5% , so that a cold-rolled sheet with a final dimension of 0.228 mm is obtained is then continuously decarburized and finally annealed at 1200 ° C for 20 hours. The magnetic properties in the rolling direction are: -.

B ₁₀ = 19,300 Gauss

= 0.72 W / kg.

10 9 8 17/0673

Claims (2)

Claims 1. A process for the production of simply oriented magnetic sheets made of steel, which have an excellent orientation in Walsrich and a high magnetic induction, by rough rolling and hot rolling a raw steel slab containing Si, C and Al, by quenching the steel sheet so that an AlN Deposition in an amount of at least 0.0005 % (N as AlN) is caused by more than one cold rolling of the steel sheet, including then with a reduction of 65 to 95% according to the Si content to be carried out cold rolling to the sheet thickness to the final dimension to bring, durch.ein decarburization annealing of the steel sheet and a final annealing at a temperature of more than 800 ⁰ C, characterized in that the raw "slab of steel 0 to 4%. Si, less than 0.085% C and 0.010 to 0.065 contains% acid-soluble Al, with the annealing treatment for the deposition of AlN in the temperature range of from 75O ° C to 1200 ⁰ C for 30 seconds to 30 minutes durchg is carried out, so that an ff conversion can take place at least on part of the steel sheet, and then the annealed steel sheet from the temperature range between 750 and 950 C according to the C and Si content to 400 ⁰ C in the time from 2 to 200 seconds is quenched. · 2. The method according to claim 1, characterized in that the steel sheet of an intermediate size, which contains 2.5 to 4.0% Si, 0.020 to 0.080 % C, 0.010 to 0.065% acid-soluble Al, the remainder Fe, 30 seconds to 30 minutes is .glühbehandelt at 950-1200 ⁰ C and then quenched from 95O ° C to 400 ⁰ C in .One time of 2 to 200 seconds. 109817/06 7 3 Blank page