EP3769862A1 - Method for producing a deep-drawable ready-made strip made of steel in a casting roller composite system - Google Patents

Abstract

The invention relates to a method for producing a finished strip (6) from steel in a composite casting and rolling plant (1). The object of the invention is to find a method by means of which a thin finished strip (6) with good deep-drawability can be produced directly on a cast-roll compound system without the finished strip (6) necessarily being pickled, cold-rolled and is annealed. This object is achieved by the method according to claim 1.

Description

Field of technology

The present invention relates to the technical field of metallurgy, specifically the production of a deep-drawable, hot-rolled finished steel strip in a composite casting and rolling plant.

Cast-roll compound systems are basically known to those skilled in the art, e.g. an Arvedi ESP system, an SMS CSP system or a Danieli QSP system. It is also known that thin or ultra-thin strips of the most varied steel grades can be produced in a particularly energy-efficient manner on compound casting and rolling systems.

State of the art

Since certain strips must have a certain deep drawability, which cannot be achieved by conventional hot rolling according to the state of the art, the microstructure of the finished strip necessary for deep drawability is achieved by hot rolling in a conventional hot rolling mill or in a casting-rolling compound plant, by pickling, subsequent cold rolling with a high degree of deformation, annealing and, if necessary, galvanizing.

Although strips with a thickness of <1 mm can be produced directly on a cast-roll compound system, the advantages of the cast-roller compound systems are partially forfeited due to the steps of hot rolling - pickling - cold rolling - annealing and, if necessary, galvanizing. Accordingly, there is a need to be able to produce thin strips with good deep-drawability directly on a casting-rolling compound system, without these necessarily having to carry out the further steps of pickling - Must go through cold rolling - annealing and, if necessary, galvanizing.

Summary of the invention

The object of the invention is to modify the known processes for the production of thin steel strips in such a way that a thin finished strip with good deep-drawability can be produced directly on a casting and rolling compound plant without the finished strip necessarily being pickled, cold-rolled and cold-rolled after hot rolling needs to be annealed.

This object is achieved by a method according to claim 1. Advantageous embodiments are the subject of the dependent claims.

• eine Stranggießanlage zum Stranggießen eines Strangs,
• eine Vorwalzstraße zum Vorwalzen des Strangs zu einem Vorband,
• eine Fertigwalzstraße mit mehreren Fertiggerüsten zum Fertigwalzen des Vorbands zu einem Fertigband, und
• zumindest eine Wickeleinrichtung zum Aufwickeln des Fertigbands,

aufweist, umfassend die Verfahrensschritte:

• Stranggießen von flüssigem Stahl zu dem Strang mit Brammen- oder Dünnbrammenquerschnitt in der Stranggießanlage, wobei der flüssige Stahl C < 0,01% (bevorzugt C < 0,004%), Mn < 0,2%, P < 0,01%, optional Ti+Nb ≥ 0,01%, der Rest Fe und etwaige Verunreinigungen (auch Begleitelemente genannt) enthält;
• Vorwalzen des ungeschnittenen Strangs zu dem Vorband in der Vorwalzstraße, wobei der letzte Walzstich in der Vorwalzstraße im austenitischen Bereich erfolgt und die Dicke des Strangs durch das Vorwalzen um zumindest 30%, bevorzugt zumindest 60%, besonders bevorzugt zumindest 80% reduziert wird;
• zumindest teilweise Phasenumwandlung des Austenits im Vorband zu Ferrit vor dem Fertigwalzen;
• Fertigwalzen des ungeschnittenen, zumindest teilweise phasenumgewandelten Vorbands in der Fertigwalzstraße durch mehrere Walzstiche zu dem Fertigband, wobei das Fertigband nach dem letzten Walzstich eine Dicke zwischen 0,5 und 4 mm, bevorzugt zwischen 0,6 und 2 mm aufweist;
• Walzspaltschmierung beim letzten Walzstich, bevorzugt bei mehreren der abschließenden Walzstiche, besonders bevorzugt bei sämtlichen Walzstichen, in der Fertigwalzstraße, wodurch die Reibung zwischen den Arbeitswalzen eines Fertiggerüsts und dem Walzgut reduziert wird, sodass Scherbänder im Fertigband, die zur Entwicklung einer unerwünschten GOSS-Textur führen, verhindert werden;
• Aufwickeln des Fertigbands in der Wickeleinrichtung, sodass der Ferrit im Fertigband zumindest teilweise eine {1 1 1} Textur ausbildet.

Specifically, the solution takes the form of a process for the production of a finished steel strip in a composite casting and rolling system, the composite casting and rolling system

• a continuous caster for the continuous casting of a strand,
• a pre-rolling train for pre-rolling the strand into a pre-strip,
• a finishing train with several finishing stands for finishing rolling the pre-strip into a finished strip, and
• at least one winding device for winding the finished strip,

comprising the process steps:

• Continuous casting of liquid steel to form the strand with a slab or thin slab cross-section in the continuous caster, the liquid steel being C <0.01% (preferably C <0.004%), Mn <0.2%, P <0.01%, optionally Ti + Nb ≥ 0.01%, the remainder contains Fe and any impurities (also called accompanying elements);
• Rough rolling of the uncut strand to the roughing strip in the roughing train, the last rolling pass in the roughing train taking place in the austenitic area and the thickness of the strand by the roughing rolling by at least 30%, preferably at least 60%, particularly preferably at least 80%, is reduced;
• at least partial phase transformation of the austenite in the sliver to ferrite before the finish rolling;
• Finish rolling the uncut, at least partially phase-converted preliminary strip in the finishing train through several rolling passes to form the finished strip, the finished tape having a thickness between 0.5 and 4 mm, preferably between 0.6 and 2 mm, after the last rolling pass;
• Roll gap lubrication for the last rolling pass, preferably for several of the subsequent rolling passes, particularly preferred for all rolling passes, in the finishing mill, which reduces the friction between the work rolls of a finishing stand and the rolling stock, so that shear bands in the finished strip that lead to the development of an undesirable GOSS texture , be prevented;
• Winding up the finished strip in the winding device so that the ferrite in the finished strip at least partially forms a {1 1 1} texture.

The composite casting and rolling plant for carrying out the method according to the invention comprises at least one continuous casting plant for continuously casting a strand, a roughing mill for roughing the strand to form a roughing strip, a finishing mill with several finishing stands for finishing the Pre-strip to a finished strip, and at least one winding device for winding up the finished strip. The roughing train comprises one or more roughing stands.

In the continuous casting plant, liquid steel is first continuously cast into a strand with a slab or thin slab cross-section, with the liquid steel C <0.01% (preferably C <0.004%), Mn <0.2%, P <0.01%, preferably Ti + Nb ≥ 0.01%, the remainder contains Fe and any impurities or other accompanying elements (Percentages in each case in% by weight). The endless strand is then rolled into a pre-strip in the roughing train, the last rolling pass in the roughing train taking place in the austenitic area and the thickness of the strand being reduced by at least 30%, preferably at least 60%, particularly preferably at least 80%, by the roughing . Following the roughing, there is at least a partial phase transformation of the austenite in the roughing strip to ferrite, so that the roughing strip enters the finishing rolling train fully or partially ferrite. In the finishing train, the endless strand of the at least partially phase-converted preliminary strip is hot-rolled to the finished strip by several rolling passes, the finished strip having a thickness between 0.5 and 4 mm, preferably between 0.6 and 2 mm, after the last rolling pass. In order to prevent the formation of shear bands in the finished strip, which lead to the development of the undesirable GOSS texture, nip lubrication is preferred for the last pass, preferably for several of the subsequent passes (e.g. for the last and penultimate pass), particularly preferred for all Roll passes, used in the finishing rolling train, with the roll gap in each case being lubricated, for example by a liquid lubricant such as an oil or mineral oil. After the finish rolling, the finished strip is wound up in the winding device, the ferrite in the finished strip at least partially forming a {1 1 1} texture. The so-called {1 1 1} texture of the ferrite is responsible for ensuring that the finished strip is easy to deep-draw. Basically, the more ferrite with the {1 1 1} texture there is in the finished strip, the better the deep-drawability. If the liquid steel contains Ti and / or Nb, the sum of these alloying elements Ti + Nb ≥ 0.01%, the finished strip achieves a further improved deep drawing ability, since a ferritically rolled, titanium and / or niobium alloyed finished strip has a higher proportion of ferrite with the {1 1 1} texture. In many cases, the addition of Ti and / or Nb can be dispensed with for subordinate requirements.

Continuous operation in the compound casting and rolling system ensures optimum process stability and, as a result, uniform strip geometry and mechanical properties.

To reduce frictional stresses in the roll gap, it is advantageous if the roll gap has a low ratio of compressed length and mean roll gap height. This is achieved in that the diameter of the work rolls in the last rolling pass, preferably in several of the final rolling passes, particularly preferably in all rolling passes, in the finishing rolling train is between 200 mm and 750 mm, preferably 200 mm to 500 mm.

To further reduce frictional stresses in the roll gap, it is advantageous if the coefficient of friction μ between a work roll and the rolling stock in the last rolling pass, preferably in several of the final rolling passes, particularly preferably in all rolling passes, in the finishing rolling train is μ ≤ 0.15. This can be achieved through roll gap lubrication and / or through particularly smooth surfaces of the work rolls.

Typically, the degree of deformation of the first pass in the finishing train is greater than the degree of deformation of the last pass, or all passes show a degressive course of deformation, i.e. the degree of deformation of an earlier pass is greater than the degree of deformation of a later pass.

For the formation of a high proportion of ferrite with a {1 1 1} texture, it is advantageous if the total degree of deformation of all rolling passes in the finishing train is ≥ 70%.

There are two possibilities with regard to the temperature control in the compound casting and rolling system. According to option 1, the temperature of the pre-strip at the exit from the pre-rolling train is ≥ 900 ° C, the temperature of the finished strip at Exit from the finishing train between 700 and 800 ° C, and the coiling temperature> 680 ° C. According to option 2, the temperature of the pre-strip at the exit from the roughing train is ≥ 900 ° C, the temperature of the finished strip at the exit from the finishing train is <750 ° C, and the winding temperature is <600 ° C.

When using option 2, it is advantageous to anneal the finished strip for recrystallization after winding. The advantage of option 1 is that recrystallization annealing is not required.

If the sliver is descaled before finish rolling, it is typically necessary to heat the sliver, preferably inductively.

After heating, the pre-strip is descaled and optionally additionally intensively cooled by a liquid coolant (see "Power Cooling" from Primetals Technologies).

For the formation of the desired {1 1 1} texture in the finished strip, it does not matter whether the pre-strip is descaled before or after cooling. Preferably, however, the descaling takes place before the intensive cooling.

Either the strand or the pre-strip is preferably covered with a powder that hinders scaling, so that the pre-strip enters the finishing rolling train fully or partially ferritically after active or passive cooling. In this embodiment, it is advantageous that descaling is omitted and therefore in most cases there is no need to heat the pre-strip. The powder can, for example, be a borate, in particular a salt of boric acid, particularly preferably a sodium salt of boric acid, very particularly preferably borax with or without crystal water, such as anhydrous borax (Na ₂ B ₄ O ₇ ), borax pentahydrate (Na ₂ B ₄ O ₇ · 5H ₂ O) or Borax decahydrate (Na ₂ B ₄ O ₇ · 10H ₂ O), or the powder contain at least one of these compounds.

With certain temperature controls, it may be necessary to cool the finished strip in the cooling section.

Brief description of the drawings

Fig 1

eine schematische Darstellung einer ersten Gieß-Walz-Verbundanlage zur Durchführung des erfindungsgemäßen Verfahrens,

Fig 2

eine schematische Darstellung einer zweiten Gieß-Walz-Verbundanlage zur Durchführung des erfindungsgemäßen Verfahrens,

Fig 3

ein Dickenprofil für drei Varianten des erfindungsgemäßen Verfahrens,

Fig 4

ein Temperaturprofil für drei Varianten des erfindungsgemäßen Verfahrens.

The above-described properties, features and advantages of this invention and the manner in which they are achieved will become clearer and more clearly understood in connection with the following description of several exemplary embodiments, which are explained in more detail in connection with the drawings. It shows:

Fig 1

a schematic representation of a first composite casting and rolling system for carrying out the method according to the invention,

Fig 2

a schematic representation of a second composite casting and rolling system for performing the method according to the invention,

Fig 3

a thickness profile for three variants of the method according to the invention,

Fig 4

a temperature profile for three variants of the method according to the invention.

Description of the embodiments

In the compound casting and rolling system 1 of the Fig 1 is in the continuous casting plant 2 liquid steel with the following chemical composition <i> Table 1: Chemical composition of the steel </i> element Weight% C. <0.004 Mn <0.2 P <0.01 Ti + Nb 0.03 Fe rest continuously cast into a strand 3 with a slab cross-section. The strand 3 leaves the continuous caster 2 with a thickness of 110 mm and a speed of 6 m / min. The strand 3 enters the three-stand roughing train 5 uncut and is there reduced to a roughing strip 4 with a thickness of 10 mm. The last rolling pass in stand R3 of roughing train 5 takes place in the austenitic temperature range at a final rolling temperature of 950 ° C. The temperature of the pre-strip 4 is then heated to 1050 ° C. by an induction furnace IH, and the temperature of the pre-strip is then cooled to 800 ° C. by descaling D and intensive cooling 7. The austenite present in the preliminary strip 4 is largely or almost completely converted into ferrite. The endless, partially phase-changed preliminary strip 4 then enters the five-stand finishing rolling train 8 and is there finish-rolled in 5 passes to form a finished strip 6 with a thickness of 1 mm. The last three rolling passes in the roll stands F3, F4 and F5 of the finishing train 8 are carried out using roll gap lubrication. A mineral oil is sprayed on between the work rolls of a finishing stand and the rolling stock, which reduces the coefficient of friction in the roll gap to a value µ <0.15. This prevents shear bands, which lead to the development of an undesirable GOSS texture, from forming in the finished band. The finished strip 6 leaves the finishing train 8 at a temperature of 720 ° C. and is wound into bundles in the winding device DC without being cooled by liquid in the subsequent cooling section. The Winding temperature is 690 ° C. Shortly before the bundle reaches its target weight, the endless finished band is cut by the scissors 10 and wound onto another (in Fig 1 winding device (not shown) continued, the ferrite in the finished strip 6 at least partially forming a {1 1 1} texture.

The Fig 2 shows a second variant of a composite casting and rolling installation 1 for carrying out the method according to the invention.

In the Figures 3 and 4 are three further variants, called V1 to V3, of operating methods for producing a finished strip 6 from steel on the compound casting-rolling system 1 of Fig 2 shown. The variants V1 and V2 are on the cast-roll compound system 1 according to Fig 1 carried out; the variant V3 on the casting-rolling compound system 1 according to Fig 2 .

According to variant V3, the pre-strip 4 heated in the induction furnace IH and descaled in the descaling device D is fed directly to the first stand F1 of the finishing train 8 without being further cooled by an intensive cooling 7. As a result, the compound casting and rolling system 1 are the Fig 2 and the operating method V3 is further simplified.

In the continuous caster 3, in variants V1, V2 and V3, liquid steel with the chem. Composition cast into a 90 mm thick thin slab strand 3. The thin slab strand 3 leaves the continuous caster 2 at a casting speed of 6 m / min and a temperature of 1100 ° C. Since the pre-rolling train 5 directly follows the continuous caster 2, the uncut thin slab strand also enters the first stand R1 of the pre-rolling train 5 at 1100 ° C and becomes a pre-strip 4 with a thickness of in the three stands R1 ... R3 of the pre-rolling train 5 12.4 mm rough rolled. The last pass in stand R3 of roughing train 5 takes place at 1000 ° C and thus in austenitic temperature range of the steel. The pre-rolling reduces the thickness of the strand by 86%.

In the case of variants V1 and V2, the pre-strip 4 is then heated to 1100 ° C. in the induction furnace IH and then descaled in the descaling device D. The temperature of the pre-strip 4 drops to 1000 ° C. in the process. The sliver is then intensively cooled in the intensive cooling system 7, the temperature of the sliver 4 falling to below 900 ° C.

In variant V3, the pre-strip 4 is neither heated in the induction furnace IH nor descaled in the descaling device D. It would just as well be possible to omit the induction furnace IH and the descaling device D. It should be clear that the surface quality of the finished strip 6 may not meet expectations due to the omission of the descaling. On the other hand, high energy efficiency is more important than high surface quality for some applications. As shown above, the scaling of the strand or the pre-strip can be reduced or prevented by a powder. In this case, the method according to the invention has a high energy efficiency and the finished strip has a high surface quality.

Due to the temperature control of the pre-strip 4 after the last pass R3 in the pre-rolling train 5 and before the first pass F1 in the finishing train 8, the austenite in the pre-strip 4 is at least partially converted into ferrite. Subsequently, the at least partially phase-converted sliver 4 enters uncut into the first stand F1 of the finishing train 8.

According to variant V1, the first rolling pass takes place in the first stand F1 of the finishing rolling train 8 at 875 ° C. The last rolling pass in the fifth stand F5 of the finishing train 8 takes place at a final rolling temperature of 735 ° C. The finished strip 6 with a thickness of 1.7 mm passes through the cooling section 9 without being cooled and is at a winding temperature of 690 ° C on the DC winding device wound up. It would also be possible to omit the cooling section 9, ie to arrange the winding devices DC immediately after the last stand F5 of the finishing rolling train 8. Since, however, mostly different products are produced on a composite casting and rolling system 1, a cooling section 9 is typically present.

In the case of variants V2 and V3, the first rolling pass takes place in the first stand F1 of the finishing train 8 at 840 ° C. The last rolling pass in the fifth stand F5 takes place at a final rolling temperature of 700 ° C. The finished strip 6 with a thickness of 1.7 mm is cooled further in the cooling section 9 and wound onto the winding device DC at a winding temperature of 550 ° C.

In all three variants, the thickness of the pre-strip is reduced by 86% by finish rolling.

The last three rolling passes in the rolling stands F3, F4 and F5 of the finishing train 8 are again carried out using roll gap lubrication.

The temperatures in the individual units of the composite casting and rolling system 1 according to variants V1 to V3 result from either Fig 4 or the following table: <i> Table 2: Temperature control </i> Temperature [° C] V1 V2 V3 CCM Out 1100 1100 1100 R1 1100 1100 1100 R2 1050 1050 1050 R3 1000 1000 1000 IH In 900 900 900 IH Out 1100 1100 880 D. 1000 1000 870 F1 875 840 840 F2 840 805 805 F3 805 770 770 F4 770 735 735 F5 735 700 700 DC 690 550 550

The reduction rates in the individual stands R1 ... R3 and F1 ... F5 and the thicknesses of the thin slab 2, the pre-strip 4 and the finished strip 6 according to the variants V1 to V3 result from either Fig 3 or the following table: <i> Table 3: Thicknesses and reduction rates </i> Thickness [mm] Reduction rates [%] V1 V2 V3 V1 V2 V3 CCM Out 90.0 90.0 90.0 R1 In 90.0 90.0 90.0 50 50 50 R1 Out 45.0 45.0 45.0 R2 In 45.0 45.0 45.0 50 50 50 R2 Out 22.5 22.5 22.5 R3 In 22.5 22.5 22.5 45 45 45 R3 Out 12.4 12.4 12.4 IH In 12.4 12.4 12.4 IH Out 12.4 12.4 12.4 D. 12.4 12.4 12.4 F1 In 12.4 12.4 12.4 45 45 45 F1 Out 6.8 6.8 6.8 F2 In 6.8 6.8 6.8 40 40 40 F2 Out 4.1 4.1 4.1 F3 In 4.1 4.1 4.1 35 35 35 F3 Out 2.7 2.7 2.7 F4 In 2.7 2.7 2.7 25th 25th 25th F4 Out 2.0 2.0 2.0 F5 In 2.0 2.0 2.0 15th 15th 15th F5 Out 1.7 1.7 1.7 DC 1.7 1.7 1.7

In order to ensure the endless operation of the composite casting and rolling installation 1, the finished strip 6 is cut directly in front of the winding devices and alternately wound up by at least two winding devices DC.

By using the method according to the invention in the composite casting and rolling installation 1, the wound finished strip 6 has good deep-drawability without the finished strip 6 having to be cold-rolled or annealed after hot rolling. Since the finished strip is wound at a relatively low temperature in the V2 and V3 variants, no recrystallization takes place in the coil itself. Therefore, the finished strip should subsequently be subjected to a recrystallization annealing. However, even if the finished strip 6 is still cold-rolled and annealed for higher requirements, the method according to the invention is extremely advantageous, since the cold-rolling can be carried out with lower reduction rates and the annealing time can be greatly shortened. The good deep-drawability results on the one hand from the chem. Composition of the liquid steel and the advantageous application of the method according to the invention.

Although the invention has been illustrated and described in more detail by the preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

List of reference symbols

1

Cast and roll compound system

2, CCM

Continuous caster

3

strand

4th

Opening act

5

Roughing mill

6th

Finished tape

7th

Intensive cooling

8th

Finishing mill

9

Cooling section

10

scissors

D.

Descaling device

DC

Winding device

F1 ... F5

First to fifth stands of the finishing mill

IH

Induction furnace

In

Receipt of an aggregate

Out

Output of an aggregate

R1 ... R3

First to third stands of the roughing mill

Claims (13)

A method for producing a finished strip (6) made of steel in a composite cast-and-roll system (1), the composite cast-and-roll system (1) having: - a continuous casting plant (2) for continuously casting a strand (3), - a pre-rolling train (5) for pre-rolling the strand (3) to form a pre-strip (4), - A finishing train (8) with several finishing stands for finishing rolling the pre-strip (4) to form the finished strip (6), and - At least one winding device (DC) for winding up the finished strip (6), comprehensive the process steps: - Continuous casting of liquid steel to form the strand (3) with slab or thin slab cross-section in the continuous caster (2), the liquid steel in weight% C <0.01%, Mn <0.2%, P <0.01% , optionally Ti + Nb ≥ 0.01%, the remainder containing Fe and any impurities; - Pre-rolling the uncut strand (3) to the pre-strip (4) in the pre-rolling train (5), with the last pass (R3) in the pre-rolling train (5) taking place in the austenitic area and the thickness of the strand (3) by the pre-rolling at least 30%, preferably at least 60%, particularly preferably at least 80% is reduced; - At least partial phase transformation of the austenite in the pre-strip (4) to ferrite before finish rolling; - Finishing rolling of the uncut, at least partially phase-converted preliminary strip (3) in the finishing rolling train (8) through several rolling passes to form the finished strip (6), the finished strip (6) having a thickness between 0.5 and 4 mm after the last rolling pass (F5) , preferably between 0.6 and 2 mm; - Roll gap lubrication for the last rolling pass (F5), preferably for several of the subsequent rolling passes (F3 ... F5), particularly preferred for all rolling passes (F1 ... F5), in the finishing train (8), whereby the friction between the work rolls of a finishing stand and the rolling stock is reduced; - Winding up of the finished tape (6) in the winding device (DC). Method according to claim 1, characterized in that the diameter of the work rolls in the last rolling pass, preferably in several of the final rolling passes, particularly preferably in all rolling passes, in the finishing rolling train is between 200mm and 750mm, preferably 200mm to 500mm. Method according to claim 1 or 2, characterized in that the coefficient of friction µ between a work roll and the rolling stock in the last rolling pass, preferably in several of the final rolling passes, particularly preferably in all rolling passes, in the finishing rolling train (8) is µ ≤ 0.15. Method according to one of Claims 1 to 3, characterized in that the degree of deformation of the first pass in the finishing rolling train (8) is greater than the degree of deformation of the last pass. Method according to one of Claims 1 to 4, characterized in that the total degree of deformation of all rolling passes in the finishing rolling train (8) is ≥ 70%. Method according to one of Claims 1 to 5, characterized in that the temperature of the pre-strip (4) when exiting the pre-rolling train (5) is ≥ 900 ° C, the temperature of the finished strip (6) when exiting the finishing-rolling train (8) is between 700 and 800 ° C, and the winding temperature is> 680 ° C. Method according to one of Claims 1 to 5, characterized in that the temperature of the pre-strip (4) when it emerges from the roughing train (5) is ≥ 900 ° C, the temperature of the finished strip (6) at the exit from the finishing train (8) <750 ° C, and the winding temperature is <600 ° C. Method according to Claim 7, characterized in that the finished strip (6) is annealed for recrystallization after being wound. Method according to one of Claims 1 to 8, characterized in that the preliminary strip (4) is heated, preferably inductively, before the finish rolling. Method according to Claim 9, characterized in that the pre-strip (4) is descaled after heating and before the finish rolling and optionally additionally cooled by a liquid coolant. Method according to one of claims 1 to 10, characterized in that either the strand (3) or the pre-strip (4) is covered with a covering powder which hinders scaling and the pre-strip (4) is fully or partially ferritic after active or passive cooling the finishing train (8) enters. Method according to claim 11, characterized in that the pre-strip (4) is descaled before or after cooling. Method according to one of Claims 1 to 12, characterized in that the finished strip (6) is cooled in the cooling section (9).

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