DE102022129242A1 - Process for producing a non-grain-oriented electrical steel strip - Google Patents

Abstract

The invention relates to a method for producing a non-grain-oriented electrical steel strip. The following method steps are provided:(A) producing a hot-rolled non-grain-oriented electrical steel strip;(B) cold rolling of the electrical steel strip provided in step (A);(C) final annealing and cooling of the cold steel strip obtained in step (B).For the final annealing, a strip tension acting on the strip during the final annealing is set depending on a predetermined magnetic property of the grain-oriented electrical steel strip obtained.

Description

The invention relates to a method for producing a non-grain-oriented electrical steel strip.

Non-grain-oriented electrical steel is required in many electrical engineering applications and is well known in practice.

Non-grain-oriented electrical steel, often referred to as "NO electrical steel" or "NGO Electrical Steel" (NGO = Non Grain Oriented), is used, for example, as a base material for the manufacture of components of a rotating electrical machine. In such an application, the non-grain-oriented metallic electrical steel is used to influence the course of electromagnetic fields. Typical applications for such steels are rotors and stators in electric motors and electric generators.

Many electric motors require operation at high speeds per unit of time, for example motors that are being developed for applications in the context of so-called electromobility and are therefore becoming increasingly important. The operation of an electric motor at high speeds is accompanied by high frequencies of the required alternating electromagnetic field, which is ultimately the basis for driving the motor. Materials are therefore increasingly required that are designed for use in alternating electromagnetic fields with comparatively high frequencies.

When developing electric motors for operation with high-frequency alternating fields, the material developer is faced with the challenge of contributing to increasing the efficiency of the electric motor.

Against this background, non-grain-oriented metallic flat products, in particular non-grain-oriented electrical steel, are required which combine comparatively low core losses at comparatively high frequencies with a comparatively high magnetic polarization and induction as well as comparatively high permeability, in particular in the relevant ranges of the magnetic field strength, namely at comparatively low magnetic field strength.

Good combinations of these properties are achieved in proven electrical strips and sheets by a high weight proportion of silicon and/or aluminum in the starting alloy of the electrical strip or sheet. However, high proportions of these elements are usually accompanied by the disadvantageous effect that corresponding previously known NO electrical strips or NO electrical sheets with the properties mentioned have a comparatively high degree of brittleness due to their high silicon and/or aluminum content, with the associated disadvantages in processability, for example in cold rolling. For example, strip tears can occur more frequently during cold rolling of corresponding NO electrical strip. The acceptable degree of brittleness is in turn linked to the grain thickness in the electrical strip or sheet, so that an optimization of the material properties over opposing physical effects is necessary.

Against the background of the above explanations, the object of the invention is to provide alternatives to known electrical strips or sheets which, with regard to their magnetic properties on the one hand and their mechanical properties on the other hand, meet the requirements to a constant or higher degree, but also enable a design in small thicknesses.

The invention is solved by a method for producing a non-grain-oriented electrical steel strip having the features of claim 1.

1. (A) Herstellen eines warmgewalzten, optional warmbandgeglühten, nicht kornorientierten Elektrobands;
2. (B) Kaltwalzen des in Schritt (A) bereitgestellten Elektrobands auf eine Dicke zwischen 0,150 mm und 0,400 mm, bevorzugt zwischen 0,200 mm und 0,330 mm;
3. (C) Schlussglühen und Abkühlen des in Schritt (B) erhaltenen Kaltbands, um das nicht kornorientierte Elektroband zu erhalten.

The procedure comprises at least the following steps:

1. (A) producing a hot-rolled, optionally hot-strip annealed, non-grain-oriented electrical steel strip;
2. (B) cold rolling the electrical steel strip provided in step (A) to a thickness between 0.150 mm and 0.400 mm, preferably between 0.200 mm and 0.330 mm;
3. (C) final annealing and cooling of the cold rolled strip obtained in step (B) to obtain the non-grain oriented electrical steel strip.

According to the invention, the final annealing is carried out in a continuous furnace. During the final annealing, a strip tension acting on the strip is adjusted depending on a predetermined magnetic property which the resulting grain-oriented electrical steel strip should have.

The provision of the non-grain-oriented electrical steel strip of higher thickness, as mentioned in step (A), will not be explained in more detail here, as it is a process well known to those skilled in the art. For example, the non-grain-oriented electrical steel strip of higher thickness can be produced using a conventional production route via a continuous casting plant or via thin slab production. In both routes, a steel melt with a suitable specification, for example of the type mentioned at the beginning, is melted into a starting material and cast into a starting material, which in conventional production can be a slab or a thin slab.

The raw material produced in this way can then be heated to a raw material temperature of, for example, between 1100 and 1300 degrees Celsius. If necessary, the raw material is reheated or kept at the respective target temperature using the casting heat.

The pre-material heated in this way can then be hot-rolled into a hot strip with a thickness of, for example, between 1 mm and 3 mm, preferably between 1.5 mm and 2.5 mm.

Hot rolling begins, for example, in a manner known per se, at a hot rolling initial temperature in the finishing stage of 900 to 1150 degrees Celsius and ends, for example, with a hot rolling final temperature of 700 to 920 degrees Celsius, in particular 780 to 850 degrees Celsius.

The hot strip obtained can then be cooled to a coiling temperature and coiled into a coil. The coiling temperature is ideally chosen so that problems are avoided during the subsequent cold rolling. In practice, the coiling temperature is, for example, at most 700 degrees Celsius, preferably 550 to 700 degrees Celsius.

The hot-rolled electrical strip or sheet from step (A) can be transferred directly, i.e. immediately afterwards, to step (B) of the process according to the invention. In a preferred embodiment of the process according to the invention, however, after step (A) and before step (B) in a step (A') hot strip annealing is carried out at a temperature of 700 to 800 degrees Celsius, preferably at a temperature of 720 to 1000 degrees Celsius, depending on the process used, for example batch annealing or continuous annealing.

During experiments for the present work, it was surprisingly shown that the magnetic properties of electrical steel strips, largely independent of their exact composition, not only showed a qualitative dependence on the strip tension during the final annealing, but rather a systematic and continuous change in the magnetic properties of the strip tension could be observed. It is proposed to use this knowledge to

Experiments have shown that particularly good results in terms of magnetic properties are obtained when the specific infeed belt tension is at most 3 N/mm ² , preferably at most 2 N/mm ² , particularly preferably at most 1.7 N/mm ² , and/or the specific outfeed belt tension is at most 3 N/mm ² , preferably at most 2 N/mm ² , particularly preferably at most 1.7 N/mm ² . Alternatively or additionally, the sum of the infeed belt tension and the outfeed belt tension can be considered, in which case the sum of the specific infeed belt tension and the specific outfeed belt tension should be at most 6 N/mm ² , preferably at most 4 N/mm ² , particularly preferably at most 3.4 N/mm ² . Preferably, all three conditions are met simultaneously.

The specific strip tension is the result of the quotient of the strip tension, which is a force with the unit N, and the cross-section of the strip. When transporting steel strip, the strip tension is a quantity known to the expert, and its measurement and monitoring is a common professional measure when operating strip lines. The measurement can be carried out, for example, using a commercially available force sensor, also known as a strain gauge, with a measuring amplifier.

Particularly preferably, the electrical steel strip is transported with an infeed roller stand positioned in front of the continuous furnace as viewed in the direction of strip transport with the infeed belt train and with an outfeed roller stand positioned after the continuous furnace as viewed in the direction of strip transport with the outfeed belt train.

The preferred magnetic property is a predetermined maximum loss, i.e. maximum remagnetization loss, at a specified frequency and a specified polarization. Alternatively, the predetermined magnetic property can be a predetermined polarization at a specified control level. Both values have the advantage that they are values that are usually considered for sections of electrical steel strip and can therefore be determined without any special effort.

The magnetization losses can be calculated, for example, in terms of EN 60404-2:2009-01 : Magnetic materials - Part 2: Method for determining the magnetic properties of electrical steel strip and sheet using an Epstein frame". The formula symbol P(1.0T;50Hz), for example, symbolizes core losses in watts per kilogram, in short: W/kg, in an alternating electromagnetic field with a core frequency of 50 Hz and a magnetic flux density of 1.0 T in the material. The same applies analogously to other numerical values given in brackets; for example, P(1.0T;400Hz) or P(1.0T;2000Hz) or another suitable value can be considered. Since P is a thickness-dependent parameter, it applies to the measured sample as it is, whereby the thickness of the sample can be between 0.200 mm and 0.300 mm, for example.

Alternatively, the magnetic polarization can be considered at a given field strength and frequency, also referred to collectively as the modulation: The formula symbol J100;50Hz denotes, for example, a magnetic polarization at a magnetic field strength of 100 A/m in an alternating electromagnetic field with 50 Hz. Methods for determining polarization and field strength are known to the person skilled in the art, for example by means of an Epstein frame for determining the polarization, in particular according to EN 60404-2:2009-01 : Magnetic materials - Part 2: Method for determining the magnetic properties of electrical steel strip and sheet using an Epstein frame. The polarization applies in particular to the measured sample as it is presented according to the invention, the thickness of the sample advantageously being between 0.200 mm and 0.300 mm.

1. (i) Durchführen der Schritte (A) bis (C), wobei der Schritt (C) jeweils mit einem niedrigen Bandzug, einem hohen Bandzug und einem zwischen dem niedrigen Bandzug und dem hohen Bandzug liegenden mittleren Bandzug durchgeführt wird zum jeweiligen Erhalten einer entsprechenden Bandprobe.

According to an advantageous embodiment, adjusting the strip tension acting on the strip as a function of a predetermined magnetic property of the grain-oriented electrical strip obtained comprises the following steps:

1. (i) performing steps (A) to (C), wherein step (C) is performed with a low tape tension, a high tape tension and an intermediate tape tension between the low tape tension and the high tape tension to obtain a corresponding tape sample, respectively.

For example, adjusting the belt tension acting on the belt is to be understood as adjusting the sum of the specific infeed belt tension and the specific outfeed belt tension, and a high belt tension is between 10 and 20 N/mm ² , and a small belt tension is between 1 and 8 N/mm ² , and the medium belt tension is a value that lies between the high belt tension and the small belt tension. It is not excluded that more than three values of the belt tension are considered.

For example, adjusting the belt tension acting on the belt is to be understood as adjusting the specific infeed belt tension, and a high belt tension is between 4 and 8 N/mm ² , and a small belt tension is between 1 and 3 N/mm ² , and the medium belt tension is a value that lies between the high belt tension and the small belt tension. It is not excluded that more than three values of the belt tension are considered.

• (ii) Ermitteln der magnetischen Eigenschaft für die in Schritt (i) erhaltenen Bandproben. Die magnetische Eigenschaft kann beispielsweise ein Ummagnetisierungsverlust der eingangs genannten Art oder eine magnetische Polarisation der eingangs genannten Art sein.
• (iii) Anhand der Wertepaare Magnetische Eigenschaft - Bandzug: Auswählen des Bandzugs für das Einstellen des am Band wirkenden Bandzugs.

For example, adjusting the belt tension acting on the belt is to be understood as adjusting specific outfeed belt tension, and a high belt tension is between 4 and 8 N/mm ² , and a small belt tension is between 1 and 3 N/mm ² , and the medium belt tension is a value that lies between the high belt tension and the small belt tension. It is not excluded that more than three values of the belt tension are considered.

• (ii) Determining the magnetic property for the strip samples obtained in step (i). The magnetic property can be, for example, a magnetic loss of the type mentioned above or a magnetic polarization of the type mentioned above.
• (iii) Using the value pairs Magnetic Property - Belt Tension: Select the Belt Tension for adjusting the belt tension acting on the belt.

The idea behind this procedure is that for a given type of electrical steel strip, a calibration of the strip tension is carried out against the expected magnetic properties. This means that, due to the systematic, one-off the sequence of steps (i), (ii), (iii) a relationship is known between the expected magnetic property and the strip tension. Based on the inventors' surprising discovery that the relationship between magnetic property and strip tension shows a continuous change, i.e. either a continuous increase or a continuous decrease, a clear value of a strip tension can be assigned starting from a given magnetic property. This can then be set for the final annealing of the strip, which in turn means that it is not necessary to over-fulfill the desired magnetic property. In other words: the strip tension can be optimally set in such a way that on the one hand a sufficiently good magnetic value is obtained, but on the other hand the strip tension is not lower than it should be. Potential disadvantages associated with low strip tensions, such as more unsteady strip guidance and possible disadvantages in the surface quality of the strip, can thus be avoided without having to compromise on the magnetic quality.

The selection of step (iii) can be carried out, for example, on the basis of a relationship between the magnetic property and the specific strip tension obtained by means of linear regression fitting. This consideration does not follow a closed scientific theory, but rather the obvious observation that in the relevant strip tension ranges the magnetic quantities considered show an approximately linear relationship to one another.

The selection of the strip tension acting on the strip can be carried out, for example, by selecting the highest strip tension with which the specified magnetic property is achieved, less a safety tolerance of, for example, 0.1% or 1% or 5% or 10% of the nominal value (for example in the case of magnetic loss) of the magnetic property or plus a safety tolerance of, for example, 0.1% or 1% or 5% or 10% of the nominal value (for example in the case of magnetic polarization) of the magnetic property.

The adjustment of the belt tension acting on the belt is preferably carried out, as already mentioned above as an example, by adjusting the sum of the specific infeed belt tension and the specific outfeed belt tension.

• (C1) Zunächst wird mit einer Aufheizrate von mindestens 40 K/s auf eine Temperatur zwischen 850 Grad Celsius und 950 Grad Celsius, bevorzugt zwischen 880 Grad Celsius und 920 Grad Celsius, aufgeheizt wird, und hiernach
• (C2) mit einer Aufheizrate von 5 bis 150 K/s auf eine Hochglühtemperatur zwischen 960 Grad Celsius und 1100 Grad Celsius, bevorzugt zwischen 1000 Grad Celsius und 1060 Grad Celsius, aufgeheizt wird.

Preferably, the final annealing carried out in step (C) is carried out with the following parameters:

• (C1) First, the material is heated at a heating rate of at least 40 K/s to a temperature between 850 degrees Celsius and 950 degrees Celsius, preferably between 880 degrees Celsius and 920 degrees Celsius, and then
• (C2) is heated at a heating rate of 5 to 150 K/s to a high annealing temperature between 960 degrees Celsius and 1100 degrees Celsius, preferably between 1000 degrees Celsius and 1060 degrees Celsius.

Particularly preferably, the process is adjusted such that the annealing temperature is maintained for a period of 10 to 90 seconds.

After the final annealing, the cold strip is cooled down to room temperature, whereby the cooling of the cold strip preferably takes place down to room temperature at a maximum cooling rate of 25 K/s, i.e. a cooling rate of 25 K/s is not exceeded during the entire cooling process. The controlled cooling serves in particular to prevent the formation of undesirable residual stresses in the electrical steel strip, which have adverse properties on the magnetic behavior of the strip.

• - zu mindestens 70 Vol.-Prozent aus H2 besteht, und/oder
• - bei einem Taupunkt von Tp < 0 Grad Celsius durchgeführt wird.

The annealing of step (C) preferably takes place in an annealing atmosphere which

• - consists of at least 70 vol. percent H2, and/or
• - is carried out at a dew point of Tp < 0 degrees Celsius.

Preferably, both conditions are met cumulatively.

• C: 0,0005 bis zu 0,0030;
• Si: 2,8 bis 3,4;
• Al: 0,6 bis 1,6;
• Mn: bis zu 0,6;
• P: bis zu 0,040;
• S: bis zu 0,0030;
• N: bis zu 0,0020;
• Ti: 0,0010 bis zu 0,0040;
• Nb+V+Zr+Sb+Sn+Cu+Cr+Ni+Mo: bis zu 0,1;
• Rest Fe und unvermeidbare Verunreinigungen;

bevorzugt mit einem Gehalt der Summe von C, S, N und Ti von maximal 0,0100 Gew.-%. Bei Befolgung dieser Legierungsvorschrift wird ein Elektroband der eingangs genannten Weise erhalten, einhergehend mit der entsprechend vorteilhaften Eigenschaftskombination aus magnetischen und mechanischen Eigenschaften.Even if the procedure described can be carried out for any NO material according to previous observations, it is preferred, due to the particularly good properties that can be achieved, if in step (A) electrical steel is produced from a material with the alloy specification mentioned below, where the details are given in weight percent, in short: wt.%:

• C: 0.0005 up to 0.0030;
• Si: 2.8 to 3.4;
• Al: 0.6 to 1.6;
• Mn: up to 0.6;
• P: up to 0.040;
• S: up to 0.0030;
• N: up to 0.0020;
• Ti: 0.0010 up to 0.0040;
• Nb+V+Zr+Sb+Sn+Cu+Cr+Ni+Mo: up to 0.1;
• Rest Fe and unavoidable impurities;

preferably with a content of the sum of C, S, N and Ti of a maximum of 0.0100 wt.%. By following this alloying specification, an electrical steel strip is obtained as described above, along with the correspondingly advantageous combination of magnetic and mechanical properties.

The cold rolling in step (B) is preferably carried out to a thickness of the cold strip between 0.230 mm and 0.265 mm, preferably to a thickness between 0.235 mm and 0.255 mm.

Examples

Various examples were carried out.

example 1

• Zusammensetzung, jeweils in Gew.-Prozent, Rest Fe und unvermeidbare Verunreinigungen:
  • Kohlenstoff 0,0021
  • Silizium 3,27
  • Mangan 0,13
  • Phosphor 0,011
  • Schwefel 0,0005
  • Aluminium 0,755
  • Chrom 0,028
  • Kupfer 0,009
  • Niob 0,001
  • Molybdän 0,001
  • Stickstoff 0,0016
  • Titan 0,0028
  • Vanadium 0,001
  • Nickel 0,015
  • Bor 0,0003
  • Zinn 0,002
  • Magnesium 0,0024
  • Arsen 0,003
  • Kalzium 0,0004

Hot-rolled electrical steel strip with the following composition was cold-rolled to a final thickness of 0.30 mm and then finally annealed:

• Composition, each in weight percent, balance Fe and unavoidable impurities:
  • Carbon 0.0021
  • Silicon 3.27
  • Manganese 0.13
  • Phosphorus 0.011
  • Sulphur 0.0005
  • Aluminum 0.755
  • Chromium 0.028
  • Copper 0.009
  • Niobium 0.001
  • Molybdenum 0.001
  • Nitrogen 0.0016
  • Titanium 0.0028
  • Vanadium 0.001
  • Nickel 0.015
  • Boron 0.0003
  • Tin 0.002
  • Magnesium 0.0024
  • Arsenic 0.003
  • Calcium 0.0004

The final annealing was carried out in the continuous furnace with the following parameters: Final thickness mm Furnace annealing temperature °C Hydrogen content in atmosphere % Glow time in the high glow range s 0.30 960-1000 60-80 40

These steps are carried out with a number of strip pulls for the infeed strip pull and separately for the outfeed strip pull. The magnetic properties for the strip samples obtained are determined. The magnetic losses P were determined using an Epstein frame in accordance with DIN EN 60404-2:2019-05: "Magnetic materials - Part 2: Method for determining the magnetic properties of electrical strip and sheet using an Epstein frame". Electrical sheets were cut into longitudinal and transverse strips and measured as a mixed sample in the Epstein frame.

The relationship between specific belt tensions, both for inlet and outlet, can be seen in Table 1 below: Table 1 Belt tension 50Hz 400Hz ​ Anisotropic . sample Glow temp . enema spec . Outlet spec . P1, 0 P1, 5 J100 J200 J5000 P1,0 P1,0 P1.5 A1.0 - - °C kN N/mm2 kN N/mm2 W/kg W/kg T T T W/kg relative W/kg % 1 960 1.40 4.5 1.65 5.3 1.00 2.23 0.927 1,253 1,664 14.80 107% 35.23 15.8% 2 960 0.82 2.6 0.98 3, 1 0.94 2, 14 1,019 1,278 1,661 14.36 104% 34.75 13.2% 3 980 0.46 1.5 0.55 1, 8 0.88 2.04 1,084 1,298 1,662 13.91 100% 34.24 11.9% 4 1000 0.48 1.5 0.54 1.7 0.85 2.02 1,095 1,297 1,659 13.86 100% 34.38 12.5% 5 1030 0.47 1.5 0.52 1.7 0.82 1.97 1, 112 1,297 1,659 13.89 100% 34, 64 13.0%

Table 1 shows that there is a continuous relationship between the magnetic properties and the inlet and/or outlet belt tensions.

In a case where losses P1.0;50 Hz = 1.00 W/kg can be tolerated, these are decisive as a given magnetic property for setting the strip tension acting on the strip, and comparatively large specific strip tensions can be set during the final annealing, for example with 4.5 MPa infeed strip tension and 5.3 MPa outfeed strip tension. In the event that a certain value P1.0;50 Hz between 0.80 and 1.0 W/kg is tolerated, the relationship P1.0;50 Hz infeed strip tension and the relationship P1.0;50 Hz outfeed strip tension can each be subjected to a linear regression, for example, and the relationship can be used to set the strip tension acting on the strip during the final annealing. Alternatively, the table obtained can be used as a reference for later repetitions, whereby the newly acquired knowledge of a reproducible relationship between strip tension and magnetic properties is used to adjust the strip tension based on the desired magnetic properties, whereby the strip tension is preferably maximized for given desired magnetic properties.

Example 2:

• Zusammensetzung, jeweils in Gew.-Prozent, Rest Fe und unvermeidbare Verunreinigungen:
  • Kohlenstoff 0,0024
  • Silizium 3,27
  • Mangan 0,16
  • Phosphor 0,01
  • Schwefel 0,0007
  • Aluminium 1,016
  • Chrom 0,028
  • Kupfer 0,01
  • Niob 0,001
  • Molybdän 0,001
  • Stickstoff 0,0013
  • Titan 0,002
  • Vanadium 0,001
  • Nickel 0,015
  • Bor 0,0003
  • Zinn 0,003
  • Magnesium 0,0022
  • Arsen 0,003
  • Kalzium 0,0006

Analogous tests were carried out with different steel composition and other furnace parameters:

• Composition, each in weight percent, balance Fe and unavoidable impurities:
  • Carbon 0.0024
  • Silicon 3.27
  • Manganese 0.16
  • Phosphorus 0.01
  • Sulphur 0.0007
  • Aluminum 1.016
  • Chromium 0.028
  • Copper 0.01
  • Niobium 0.001
  • Molybdenum 0.001
  • Nitrogen 0.0013
  • Titanium 0.002
  • Vanadium 0.001
  • Nickel 0.015
  • Boron 0.0003
  • Tin 0.003
  • Magnesium 0.0022
  • Arsenic 0.003
  • Calcium 0.0006

The final annealing was carried out in the continuous furnace with the following parameters: Final thickness mm Furnace annealing temperature °C Hydrogen content in atmosphere % Glow time in the high glow range s 0.250 1030 60-80 23

A similar picture emerged, namely a continuous relationship between strip tension and magnetic properties, as shown in Table 2. Based on this table, a targeted The selection and adjustment of magnetic properties is the result of the previously unknown realization that there is a continuous relationship between the technically relevant magnetic properties and the properties used in the final annealing. Table 2 Belt tension inlet spec Belt tension outlet spec thickness P1.5/50 P1.0/400 A10/400 J100 J200 kN MPa kN MPa mm W/kg W/kg T T 0.494 2.23 0.566 2.55 0.241 2.13 12.45 13.9% 1,020 1,253 0.43 1.93 0.453 2, 03 0.242 2.14 12,50 13.7% 1,022 1,256 0.638 2.87 0, 697 3, 13 0.242 2.15 12.55 13.7% 1,010 1,251 0.577 2, 60 0.646 2.91 0.242 2.16 12.52 13.8% 1,006 1,251 0.772 3.46 0, 921 4, 12 0.243 2.16 12, 67 14.0% 0.989 1,244 0.858 3, 85 1, 030 4, 62 0.242 2.17 12.74 14.0% 0.970 1,232 1, 057 4.75 1,319 5, 93 0.242 2.21 12.87 14.7% 0.936 1,220 1,199 5.40 1,370 6, 17 0.241 2.26 13.01 14.3% 0, 921 1,214 1,257 5.67 1,442 6, 51 0.241 2.29 13.24 13.3% 0.898 1,204

QUOTES INCLUDED IN THE DESCRIPTION

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Cited non-patent literature

• EN 60404-2:2009-01 [0023, 0024]

Claims (15)

Method for producing a non-grain-oriented electrical strip, comprising at least the following method steps: (A) producing a hot-rolled, optionally hot-strip annealed, non-grain-oriented electrical strip; (B) cold rolling the electrical strip provided in step (A) to a thickness between 0.150 mm and 0.400 mm, preferably between 0.200 mm and 0.330 mm; (C) final annealing and cooling the cold strip obtained in step (B) to obtain the non-grain-oriented electrical strip, wherein the final annealing is carried out in a continuous furnace, wherein for the final annealing a strip tension acting on the strip during the final annealing is set as a function of a predetermined magnetic property of the grain-oriented electrical strip obtained. Method according to one of the preceding claims, characterized in that the specific infeed belt tension is at most 3 N/mm ² , preferably at most 2 N/mm ² , particularly preferably at most 1.7 N/mm ² , and/or the specific outfeed belt tension is at most 3 N/mm ² , preferably at most 2 N/mm ² , particularly preferably at most 1.7 N/mm ² , and/or the sum of the specific infeed belt tension and the specific outfeed belt tension is at most 6 N/mm ² , preferably at most 4 N/mm ² , particularly preferably at most 3.4 N/mm ² . Method according to one of the preceding claims, characterized in that the predetermined magnetic property is a predetermined maximum loss at a fixed frequency and a fixed polarization, or the predetermined magnetic property is a predetermined minimum polarization at a fixed control. Method according to one of the preceding claims, characterized in that the adjustment of the strip tension acting on the strip as a function of a predetermined magnetic property of the grain-oriented electrical strip obtained comprises the following steps: (i) carrying out steps (A) to (C), wherein step (C) is carried out in each case with a low strip tension, a high strip tension and an average strip tension lying between the low strip tension and the high strip tension in order to obtain a corresponding strip sample; (ii) determining the magnetic property for the strip samples obtained in step (i); (iii) using the value pairs magnetic property - strip tension: selecting the strip tension for adjusting the strip tension acting on the strip. Procedure according to Claim 4 , characterized in that the selection of step (iii) is carried out on the basis of a relationship between the magnetic property and the strip tension obtained by means of linear regression fitting. Method according to one of the preceding claims, characterized in that the adjustment of the infeed belt tension acting on the belt and/or the adjustment of the outfeed belt tension acting on the belt is carried out by selecting the respective highest belt tension with which the predetermined magnetic property is achieved. Method according to one of the preceding claims, characterized in that the adjustment of the belt tension acting on the belt takes place as an adjustment of the sum of specific infeed belt tension and specific outfeed belt tension or as an adjustment of specific infeed belt tension or as an adjustment of specific outfeed belt tension. Method according to one of the preceding claims, characterized in that the electrical steel produced in step (A) has a thickness between 1 mm and 3 mm, preferably between 1.5 mm and 2.5 mm. Method according to one of the preceding claims, characterized in that the final annealing (C1) is heated at a heating rate of at least 40 K/s to a temperature between 850 degrees Celsius and 950 degrees Celsius, preferably between 880 degrees Celsius and 920 degrees Celsius, and thereafter (C2) is heated at a heating rate of at most 5 to 150 K/s to a high annealing temperature between 960 degrees Celsius and 1100 degrees Celsius, preferably between 1000 degrees Celsius and 1060 degrees Celsius. Method according to one of the preceding claims, characterized in that the annealing temperature is maintained for a period of 10 to 90 seconds. Method according to one of the preceding claims, characterized in that the annealing is carried out - in an annealing atmosphere with at least 70 vol. percent H2, and/or - at a dew point of Tp < 0 degrees Celsius. Method according to one of the preceding claims, characterized in that the cooling of the cold strip to room temperature takes place at a maximum cooling rate of 25 K/s. Method according to one of the preceding claims, characterized in that the cold rolling in step (B) is carried out to a thickness between 0.230 mm and 0.265 mm, preferably between 0.235 mm and 0.255 mm. Method according to one of the preceding claims, characterized in that the electrical steel provided in step (A) consists of: the following components, each in percent by weight, in short: % by weight: C: 0.0005 up to 0.0030; Si: 2.8 to 3.4; Al: 0.6 to 1.6; Mn: up to 0.6; P: up to 0.040; S: up to 0.0030; N: up to 0.0020; Ti: 0.0010 up to 0.0040; Nb+V+Zr+Sb+Sn+Cu+Cr+Ni+Mo: up to 0.1; remainder Fe and unavoidable impurities; preferably with a content of the sum of C, S, N and Ti of a maximum of 0.0100 wt.%. Process according to one of the preceding claims, characterized in that the content of the sum of C, S, N and Ti is a maximum of 0.0100 wt.%.