EP1506320A1

EP1506320A1 - Non-grain oriented electrical steel strip or electrical steel sheet and method for producing the same

Info

Publication number: EP1506320A1
Application number: EP03752745A
Authority: EP
Inventors: Brigitte Hammer; Karl Ernst Friedrich; Olaf Fischer; Jürgen Schneider; Carl-Dieter Wuppermann
Original assignee: ThyssenKrupp Stahl AG; ThyssenKrupp Steel AG
Current assignee: ThyssenKrupp Steel Europe AG
Priority date: 2002-05-15
Filing date: 2003-05-15
Publication date: 2005-02-16
Also published as: US20050247373A1; US7501028B2; DE10221793C1; CN100363509C; AU2003232780A1; KR20050019715A; AU2003232780B2; WO2003097884A1; KR101059577B1; JP2005525469A; CN1678762A

Abstract

The invention relates to non-grain oriented electrical steel sheets that can be produced as finally annealed or as not finally annealed sheets in such a manner that they have improved magnetic polarization values and reduced magnetic losses as compared to values so far obtained. For this purpose, when a steel having a suitable composition is cooled off, it is subjected to a temperature range, starting from an initial temperature of not more than 1300 DEG C and with the substantially complete exception of a purely austenitic microstructure ( gamma phase). In said temperature range, the steel has a austenite/ferrite two-phase mixed structure ( alpha and gamma mixed phases) so that the electrical steel sheet, after hot rolling, pickling, cold rolling and annealing of the hot-rolled strip obtained after hot rolling has a magnetic polarization J2500 >/= 1.74 T measured in the longitudinal orientation of the strip or sheet at a magnetic field strength of 2500 A/m and a value P1.5 (50) of the magnetic losses of < 4.5 W/kg measured in the longitudinal orientation of the strip at J = 1.5 T and at a frequency f = 50 Hz.

Description

NON-CORRELATED ELECTROBAND OR SHEET AND METHOD

FOR HIS PRODUCTION

The invention relates to a non-grain-oriented electrical sheet or strip and a method for producing such products.

The term “non-grain-oriented electrical sheet” here means electrical sheets falling under DIN EN 10106 (“final annealed electrical sheet”) and DIN EN 10165 (“non-final annealed electrical sheet”). In addition, more anisotropic grades are included as long as they are not considered grain-oriented electrical sheets. In this respect, the terms "electrical sheet" and "electrical steel" are used synonymously.

"J2500" or "J5000" in the following denote the magnetic polarization at a magnetic field strength of 2500 A / m or 5000 A / m. “P 1.5” is understood to mean the loss of remagnetization with a polarization of 1.5 T and a frequency of 50 Hz.

The processing industry demands that non-grain-oriented electrical sheets be made available whose magnetic polarization values are higher than conventional sheets. This applies in particular to the area of applications in which the electrical machines are electrically excited. By increasing the magnetic polarization, the

SI / cs 020172 Magnetization requirement reduced. This is accompanied by a decrease in copper losses, which in a large number of electrical machines have a significant share in the losses incurred in the operation of electrical machines.

The economic value of non-grain-oriented electrical sheets with increased permeability is considerable. Electrical machines with electrical excitation, especially industrial drives with powers that range from 1 kW to 100 kW and beyond, are the main area of application for non-grain-oriented electrical steel.

The demand for more permeable non-grain-oriented electrical sheet types not only affects non-grain-oriented electrical sheets with high losses (Pl, 5> 5 - 6 W / kg), but also sheets with medium (3.5 W / kg <Pl, 5 <5.5 W / kg ) and low losses (Pl, 5 <3.5). For this reason, efforts are being made to improve the entire spectrum of weakly, medium and highly silicated electrotechnical steels with regard to their magnetic polarization values. The electrical steel grades with Si contents of up to 2.5 mass% Si are of particular importance with regard to their market potential.

Specifically electrical sheet types that have a high value of the magnetic polarization J ₂ soo or J5000 and at the same time low values of the magnetic reversal losses Pι, ₅ at 50 Hz, advantageously <4 W / kg, are from Intersee, since with them both a reduction of the magnetic excitation current in In the case of electrically excited machines and a reduction in iron loss compared to conventional types of electrical steel with Pι, ₅ > 4 W / kg at 50 Hz can be done.

SI / cs 02017 ₂ O The magnetization losses can be reduced by increasing the Si content. This results in significantly reduced losses if the sum% Si + 2% A1 formed from the Si content and twice the Al content in steels used for the production of electrical sheets of the type in question is more than 1.4% ,

Various ways are known of how such high contents of Si and Al-containing electrical sheets can be achieved high J ₂ soo or J5000. It has been proposed in EP 0 651 061 AI to achieve high degrees of deformation during cold rolling for this purpose, this cold rolling can be carried out in two stages with intermediate annealing. It is also known that higher-permeability types of electrical sheet can be produced by intermediate annealing of the hot strip (EP 0 469 980 B1, DE 40 05 807 C2). According to the method known from EP 0 431 502 A2, a non-grain-oriented electrical sheet is finally produced by using <0.025% C, <0.1% Mn, 0.1 to 4.4% Si and 0.1 to 4.4% Steel material (AI in mass%) is first hot-rolled to a thickness of not less than 3.5 mm. The hot strip obtained in this way is then cold-rolled without recrystallizing intermediate annealing with a degree of deformation of at least 86% and subjected to an annealing treatment. The band produced according to the known method has a particularly high magnetic polarization of more than 1.7 T with a field strength J ₂ soo of 2500 A / m and low magnetic reversal losses.

In practice, however, it turns out that it is not possible with the known measures, with the for

SI / cs 020172WO a large-scale production of the necessary safety to produce electrical sheets with a total content of more than 1.4% by mass of Si and Al non-grain-oriented electrical strips or sheets which, measured in the longitudinal direction of the strip, have a magnetic polarization J ₂₅₀₀ of> 1.7 T. (The values determined for J ₂ soo in the transverse direction of the belt and the mixed values of J ₂₅₀₀ are always smaller than the values of J ₂ soo measured in the belt direction.)

Improvements with regard to higher values of J ₂₅ oo can be achieved when using highly silicified alloys of very high purity, especially with a very low Si and Ti content and at the same time a very low C content. However, this route requires additional expenditure in steel production compared to the FeSi steels commonly used in practice.

The object of the invention now is to make starting quality of the above-mentioned prior art non-grain oriented electrical steels, as final annealed as well as can be produced without additional production effort so as _not final annealed varieties that they improved a comparison with the previously achievable values have magnetic polarization and reduced magnetic reversal losses.

This object is achieved according to the invention by a non-grain-oriented electrical steel sheet or sheet with a nominal thickness of <0.75 mm, made from a steel which, in addition to iron, contains the usual unavoidable levels of impurities (for example S, Ti) and optionally available levels of Mo, Sb, Sn , Zn, W and / or V, (in mass%) C: <0.005%, Mn: <1.0%, P: <0.8%, AI: <1%

^' SI / cs 020172WO as well as Si with the stipulation 1.4% <% Si + 2% A1 <2.5% (with% Si = Si content and% A1 = Al content), the steel thus assembled starting from a initial temperature of at most 1300 ° C with essentially complete exclusion of a purely austenitic structure (γ-phase) passes through a temperature range in which it has an austenite / ferrite two-phase structure (α-, γ-mixing phases), so that the electrical sheet after hot rolling , Pickling, cold rolling and annealing the hot strip obtained after hot rolling, a magnetic polarization J2500 ≥ 1.74 T measured in the longitudinal direction of the strip or sheet at a magnetic field strength of 2500 A / m and one in the longitudinal direction of the strip at J = 1.5 T and a frequency f = 50 Hz measured value Pι, s (50) of the magnetic losses of <4.5 W / kg.

The above-mentioned object is also achieved by a method for producing a non-grain-oriented electrical steel strip or sheet obtained according to one of the preceding claims, in which the following steps are carried out:

- Casting a steel which, in addition to iron, the usual unavoidable levels of impurities (e.g. S, Ti) and optional levels of Mo, Sb, Sn, Zn, W and / or V, (in mass%) C: <0.005 %, Mn: ≤ 1.0%, P: <0.8%, AI: <1% and Si with the requirement 1.4% <% Si + 2% A1 <2.5% (with% Si = Si Content and% A1 = Al content) contains, to a preliminary product, such as a slab, a thin slab or a cast strip,

SI / cs 020172WO - Processing of the preliminary product into a hot strip in a hot rolling process at hot rolling temperatures that are set starting from <1300 ° C so that a temperature range is passed through in which the processed steel is essentially completely excluding a purely austenitic structure (γ phase) Austenite / ferrite two-phase mixed structure (α, γ mixed phases) and a ferrite area,

- So that the electrical steel or sheet after a surface treatment comprising pickling, a cold rolling and an annealing of the hot strip obtained after the hot rolling process a in the longitudinal direction of the strip or sheet with a magnetic field strength of

2500 A / m measured magnetic polarization J ₂₅ > 1.74 T and a value Pι, s (50) of the magnetic losses of <4.5 measured in the longitudinal direction of the band at J = 1.5 T and a frequency f = 50 Hz W / kg.

Surprisingly, it has been shown that the selection of a suitably composed steel alloy and the special temperature control during the hot processing of the preliminary product cast from this steel alloy can produce an electrical sheet that has significantly improved values of the magnetic losses and the magnetic permeability compared to the prior art. In this way, in the case of electrical sheets obtained according to the invention, a magnetic polarization J ₂ soo measured in the longitudinal direction of at least 1.74 T, in particular even at least 1.76 T, can be ensured. Magnetic losses P ι, ₅ of less than 4.5 W / kg, especially 4 W / kg, can also be guaranteed.

SI / cs 020172 O The prerequisite for this is that the steel used in accordance with the invention is composed in such a way that it does not have a purely austenitic structure at any time when it cools down from 1300 ° C. Instead, the composition should be selected so that a temperature range is necessary during cooling, within which the steel structure consists of a mixture of γ and α phases. It is regarded as a tolerable deviation from this regulation in the sense of the invention if pure austenite structure occurs over a maximum temperature range of 50 ° C. This means that in the event that a pure austenite structure is formed, a two-phase mixed structure must be present again after a temperature decrease of another 50 ° C at the latest.

It could be demonstrated that, if the deviation exceeds the temperature tolerance range by 50 ° C., the increase in the quality of electrical sheets achieved by the invention cannot be achieved. Therefore, during the production of the electrical steel strip according to the invention, the temperatures are preferably carried out in such a way that the critical temperature range is avoided. For this purpose, for example, the rewarming temperature of the slab in the conventional hot strip manufacturing process or the temperature of the thin slab during casting rolling or thin strip casting before hot rolling can be selected so that it lies above the two-phase area. The hot rolling end temperature is> 800 ° C.

If hot strip processing includes coiling, the coiling temperature at which the hot strip is rolled up after the hot rolling process should be <650 ° C.

SI / cs 020172WO If slabs or thin slabs of greater thickness are processed in the production of electrical sheets according to the invention, the hot rolling process usually comprises a final rolling (finished hot rolling) which takes place in a hot rolling mill comprising a plurality of roll stands. In order to produce particularly high-quality electrical sheets, the overall degree of deformation achieved in the course of the final rolling should be> 75%. Electrical sheets _{that have} magnetic polarization J ₂ soo values of more than 1.74 T with particularly low losses Pχ _{, 5} of significantly less than 4 W / kg can be produced by the degree of deformation achieved in the course of the final rolling in the two-phase mixing area is at least 35%.

It is also possible to produce electrical sheets with good properties according to the invention if the hot-rolled preliminary product before it enters the hot rolling mill has cooled down by passing through the two-phase region to such an extent that the final rolling during hot rolling takes place essentially with a ferritic structure of the processed steel.

Preferably, if the final rolling during hot rolling is carried out with steel in the ferritic state, at least one of the last forming passes is hot-rolled with lubrication. Hot rolling with lubrication results in less shear deformation on the one hand, so that the rolled strip as a result obtains a more homogeneous structure across the cross section. On the other hand, the lubrication reduces the rolling forces so that a greater decrease in thickness is possible over the respective roll pass. It can therefore be advantageous if all the forming passes in the ferrite area are carried out with roll lubrication.

SI / cs 020172WO Improved surface properties of electrical sheets according to the invention can be achieved in that the hot strip is descaled mechanically in the course of its surface treatment before pickling.

The final annealing of the electrical steel that has been cold-rolled from the hot strip can generally be carried out in a continuous process or in a hood furnace (final-annealed electrical steel). Alternatively, the annealed strip can be reshaped after the annealing carried out in a continuous or bell-type furnace with a degree of deformation <12% and then subjected to a reference annealing at temperatures above 700 ° C, so that a non-final annealed electrical steel strip is then obtained.

The invention is explained in more detail below on the basis of exemplary embodiments.

The attached diagram shows the phase diagram of a binary FeSi alloy. Analog diagrams apply to technical alloys, whereby the respective "temperatures" change compared to those in the binary alloy shown.

In the diagram, the areas in which a purely ferritic (α), a purely austenitic (γ) or a two-phase mixed structure (γ + oc) formed from ferrite and austenite are present, depending on the respective temperature and that of the respective Si Content and twice the Al content of the respective steel formed sum "% Si + 2% A1". In addition, the range within which the alloys selected according to the invention lie is delimited by the lines L _σ , L ₀ running parallel to the axis of the temperatures.

SI / cs 020172 O It can be seen that the line L ₀ marking the lower limit of the sum "% Si + 2% A1" of the Si and Al contents of alloys processed according to the invention over a temperature range T _s corresponds to the smaller amounts of the sum "% Si + 2 % A1 "extends the austenite phase region γ in which pure austenite is formed. The temperature difference, which lies between the upper intersection T _s0 and the lower intersection T _{su of} the line L ₀ with the austenite _phase region γ, is less than 50 ° C. The section A _τ cut off from the austenite phase region γ from the line L _D in the direction of the line L ₀ thus represents the tolerance range enclosed by the two-phase mixing region (γ + α), within which the embodiment of the invention forms pure Austenite may come.

The line L ₀ marking the upper limit of the sum "% Si + 2% A1" of the Si and Al contents of alloys processed according to the invention, however, just touches the limit of the two-phase mixing range (γ + α) within which two-phase mixing structure occurs. Thus, each alloy according to the invention, which has a value of its sum "% Si + 2% A1" lying between the lines L ₀ and L ₀ , passes through the two-phase mixing range (γ + α) when it is cooled from an initial temperature below 1300 ° C. ,

To demonstrate the effect of the invention, two steels S1 and S2 were melted, the compositions of which are given in Table 1 (data in% by mass, remainder iron and unavoidable impurities).

Sl / cs 020172 O

Table 1

The alloy of the steel S1 is chosen so that the structure of the steel S1 does not consist of pure austenite γ at any time when it cools down from 1300 ° C. In the case of steel S2, on the other hand, in the course of its cooling from the previously two-phase mixed structure γ + α for a temperature range T _{s of} less than 50 ° C, a briefly purely austentic structure is formed, which immediately changes again into two-phase mixed structure γ + α when the temperature decreases further.

Steels S1 and S2 were each cast into slabs, which were then reheated to a temperature below 1300 ° C. but above the limit temperature marking the transition to the two-phase mixing region (γ + α). At this reheating temperature, the slabs each had a purely ferritic structure.

The slabs were then pre-rolled and, in the course of four different tests 1 to 4, with a hot-rolling start temperature, ran into a hot-rolling mill comprising seven rolling stands, in which they were each rolled into a hot strip.

In test 1, the hot rolling starting temperature of four slabs Bl.l, B2.1, B3.1, B4.1 cast from steel S1 was so high when it entered the hot rolling mill that the steel had a two-phase mixed structure formed from austenite and ferrite. Are in the hot rolling season

SI / cs 020172 O accordingly, the slabs Bl.l to Bl.4 were first rolled in the two-phase mixing area. - The degree of deformation achieved during rolling in the two-phase mixing area was 40% and the degree of forming in the ferrite area was 66%.

Rolling in the two-phase mixing area was followed by rolling with a ferritic structure of the processed steel. In the course of this rolling in the ferrite area, a degree of forming of 66% was achieved. The hot-rolled strips, which were hot-rolled from the slabs Bl.l to Bl.4, left the hot rolling mill with a hot rolling end temperature ET and were coiled at a coiling temperature HT.

Table 2 shows the slabs Bl.l to B4.1 and the hot strips produced from them

Final hot rolling temperature ET in ° C, the reel temperature HT in ° C and the reel holding time tH in min as well as the magnetic properties Pι ₅ in W / kg, J ₂ 500 and J ₅ 00 ₀ each given in T. In addition, Table 2 for the slabs Bl.l to B4.1 shows the degrees of deformation Ug γ / α achieved in rolling in the mixed area and the degrees of deformation Ug α achieved in rolling in the ferrite area.

Table 2, experiment 1

In test 2, the hot rolling starting temperature was so low that the five slabs Bl .2 to B5.2 cast from steel S1 again had a purely ferritic structure

SI / cs 020172WO had after their structure had previously passed through the two-phase mixing range (γ + α) in the course of its cooling. As a result, hot rolling in the hot rolling mill has been carried out exclusively in ferrite. A total degree of forming Ug α of 80% was achieved. The belt surface was lubricated during the second and third stitch.

Table 3 shows the final hot rolling temperature ET in ° C, the reel temperature HT in ° C and the reel holding time tH in min as well as the magnetic properties P ₁ for the slabs B1.2 to B5.2 and the hot strips produced from them ₅ in W / kg, J ₂₅₀ o and J5000 in T.

Table 3, experiment 2

As in test 1, the hot rolling starting temperature in test 3 was so high that the slabs Bl.3, B2.3, B3.3, B4.3 cast from steel S2 had a two-phase mixed structure formed from austenite and ferrite when they entered the hot rolling mill. In the hot rolling mill, the slabs B1.3 to B .3 were therefore first rolled in the two-phase mixing area. The degree of deformation Ug γ / α achieved during this rolling was 70%. Rolling in the two-phase mixing area was followed by rolling with a ferritic structure of the processed steel. In the course of this ferrite rolling, a degree of deformation Ug α of 33% was achieved.

SI / cs 020172WO Table 4 shows the slabs Bl .3 to B4.3 and the hot strips produced from them

Hot rolling end temperature ET in ° C, the reel temperature HT in ° C and the reel holding time tH in min as well as the magnetic properties P _{1 | 5} in W / kg, J2500 and J5000 in T respectively.

Table 4, experiment 3

In trial 4, too, the hot rolling starting temperature was chosen such that the three slabs B1.4, B2.4, B3.4 cast from steel S2 had a two-phase mixed structure formed from austenite and ferrite when they entered the hot rolling mill. In the hot rolling mill, the slabs B1.4 to B3.4 were therefore also rolled in the two-phase mixing area. In contrast to experiment 3, however, a relatively low degree of deformation Ug γ / α of 40% was observed.

Rolling in the two-phase mixing area was followed by rolling with a ferritic structure of the processed steel. A degree of forming Ug α of 66% was achieved in the course of this ferrite rolling. The second and third stitch were made with lubrication of the belt surface. The finished hot-rolled hot strips left the hot rolling mill with a hot rolling end temperature ET and were coiled at a coiling temperature HT.

Table 5 shows the slabs B1.4 to B3.4 and the hot strips produced from them

SI / cs 020172 O Hot rolling end temperature ET in ° C, the reel temperature HT in ° C and the reel holding time tH in min as well as the magnetic properties P _1/5 in W / kg, J ₂ 5 ₀ o and J ₅₀ oo in T.

Table 5, experiment 4

For comparison, Table 6 shows the magnetic properties P ₁ -5 in W / kg and J ₂ 500 and J5000 in T for two conventionally produced electrical sheets offered by the applicant under the trade names M 800-50 A and 530-50 AP specified, whose alloy with a Si content of 1.3 wt .-% is such that it has a pronounced austenite range in the course of its production. The M 800-50 A electrical sheet has undergone standard production, while the 530-50 AP electrical sheet has been subjected to hot strip annealing in addition to the standard production steps.

Table 6, comparative example

For comparison, the magnetic properties P _lf5 in W / kg as well as J ₂ 5oo and J5000 for an electrical sheet Vl, which was produced by the method described in DE 199 30 519 _A1, are also given in Table 7 for comparison. The peculiarity of this procedure is that the

Sl / cs 020172WO Hot rolling is carried out at least partially in the two-phase mixing area and an overall shape change ε _h of at least 35% is achieved.

In addition, Table 7 shows the magnetic properties P, ₅ in W / kg and J ₂₅₀ o and J5000 for an electrical sheet V.2, which was produced by the process described in DE 199 30 518 AI. The special feature of this process is that during hot rolling at least the first forming pass is rolled in the austenite area and then one or more forming passes are carried out in the ferrite area with an overall shape change Sh of at least 45%.

Table 7, comparative example

It can be seen that neither the conventionally produced electrical sheet grades M 800-50 A or 540-50 AP nor the comparative sheets VI.1 and VI .2 have the magnetic values which the products according to the invention have and which can be achieved in a targeted manner using the procedure according to the invention, even then cannot be achieved if measures are taken during hot rolling that go beyond the conventional manufacturing method.

SI / cs 020172WO

Claims

PA T E N TAN S P RÜ C H E

Non-grain-oriented electrical steel or sheet with nominal thicknesses <0.75 mm, made from a steel which, in addition to iron, contains the usual unavoidable levels of impurities and optional levels of Mo, Sb, Sn, Zn, W and / or V, (in mass -%) C: <0.005%, Mn: <1.0%, P: <0.8%, AI: <1% as well

Si with the stipulation 1.4% <% Si + 2% A1 <2.5% (with% Si = Si content and% A1 = Al content), with the steel thus assembled starting from a maximum of one cooling 1300 ° C starting temperature with essentially complete exclusion of a purely austenitic structure (γ phase) passes through a temperature range in which it contains an austenite / ferrite

Two-phase mixed structure (α-, γ-mixing phases), so that after hot rolling, pickling, cold rolling and annealing of the hot strip obtained after hot rolling, the electrical sheet has a magnetic polarization J measured in the longitudinal direction of the strip or sheet at a magnetic field strength of 2500 A / m ₂ soo ≥ 1.74 T and a value Pι, s (50) of the magnetic losses of <4.5 W / kg measured in the longitudinal direction of the band at J = 1.5 T and a frequency f = 50 Hz.

SI / cs 020172

2. Non-grain oriented electrical steel or sheet according to claim 1, d a d u r c h g e k e n n z e i c h n e t, d a s s the temperature range in which an exclusively austenitic structure (γ phase) occurs in the steel during hot rolling is limited to a temperature range of less than 50 ° C.

3. Non-grain oriented electrical steel sheet or sheet according to one of the preceding claims, characterized in that its measured in the longitudinal direction magnetic polarization J ₂₅ oo ≥ 1.76 T.

4. A method for producing a non-grain-oriented electrical steel strip or sheet obtained according to one of the preceding claims, comprising the following steps:

- Casting a steel which, in addition to iron, unavoidable impurities and optionally present levels of Mo, Sb, Sn, Zn, W and / or V, (in mass%) C: <0.005%, Mn: <1.0%, P: <0.8%, AI: <1% and Si with the requirement 1.4% <% Si + 2% A1 <2.5% (with% Si = Si content and% A1 = Al content) contains, to a preliminary product, such as a slab, a thin slab or a cast strip,

- Processing the preliminary product into a hot strip in a hot rolling process at hot rolling temperatures that are set starting from <1300 ° C so that

SI / cs 020172 O a temperature range is passed through, with essentially complete exclusion of a purely austenitic structure (γ phase), in which the processed steel has an austenite / ferrite two-phase mixed structure (α, γ mixed phases),

- so that after a surface treatment comprising pickling, cold rolling and annealing of the hot strip obtained after the hot rolling process, the electrical steel sheet or sheet has a magnetic polarization J ₂₅₀₀ ≥ 1 measured in the longitudinal direction of the strip or sheet at a magnetic field strength of 2500 A / m, 74 T and a value Pι, s (50) of the magnetic losses of <4.5 W / kg measured in the longitudinal direction of the band at J = 1.5 T and a frequency f = 50 Hz.

5. The method according to claim 4, characterized in that the range of the temperature range within which the processed steel has a purely austenitic structure (γ phase) is less than 50 ° C, and that the temperatures during the hot rolling process bypassing this temperature range be performed.

6. The method of claim 4 or 5, d a d u r c h g e k e n n z e i c h n e t, that the temperature of the preliminary product before the start of the hot rolling process reaches 1150 ° C.

The method of claim 6, d a d u r c h g e k e n n z e i c h n e t, d a s s die bei

ΞI / cs 020172WO Hot rolling process reached final rolling temperature> 800 ° C.

8. The method according to any one of claims 4 to 7, d a d u r c h g e k e n n z e i c h n e t, that the reel temperature at which the hot strip is wound up after the hot rolling process is <650 ° C.

9. The method according to any one of claims 4 to 8, d a d u r c h g e k e n n z e i c h n e t that the hot rolling process comprises a final rolling taking place in a hot rolling stack comprising a plurality of roll stands.

10. The method of claim 11, d a d u r c h g e k e n n z e i c h n e t, that the overall forming degree achieved in the course of the final rolling is> 75%.

11. The method according to claim 10, d a d u r c h g e k e n n z e i c h n e t, that the degree of deformation achieved in the course of the final rolling in the two-phase mixing region is <45%.

12. The method according to claim 10, d a d u r c h g e k e n n z e i c h n e t that the degree of deformation achieved in the course of the final rolling in the two-phase mixing region is at least 35%.

13. The method of claim 9, d a d u r c h g e k e n n z e i c h n e t, that a s s the final rolling

SI / cs 020172 O only at temperatures at which the steel processed has a ferrite structure.

14. The method according to claim 9 and one of claims 12 or 13, d a d u r c h g e k e n n z e i c h n e t, d a s s the hot rolling passes carried out with a ferritic structure of the processed steel with lubrication.

15. The method according to any one of claims 4 to 14, d a d u r c h g e k e n n z e i c h n e t, that the hot strip is mechanically descaled in the course of its surface treatment before pickling.

16. The method according to any one of claims 4 to 15, d a d u r c h g e k e n n z e i c h n e t that the cold strip obtained after cold rolling is subjected to annealing in a continuous furnace.

17. The method according to claim 16, wherein the annealing takes place in a non-decarburizing atmosphere.

18. The method according to any one of claims 4 to 15, d a d u r c h g e k e n n e e c h n e t that the cold strip obtained after cold rolling is subjected to annealing in a bell annealer

SI / cs 020172WO

9. The method according to any one of claims 16 or 18, d a d u r c h g e k e n n z e i c h n e t, that post-deformed the annealed strip with a degree of deformation <12% and then subjected to a reference annealing at temperatures above 700 ° C, so that a final annealed electric fire is obtained.

SI / cs 020172WO