DE102009032358A1 - Method for continuous or discontinuous production of hot rolled strips from steel, comprises subjecting a cast strip as pre-band to a heat treatment process and subsequently rolling up or stacking as hot-rolled strip - Google Patents

Abstract

The method comprises subjecting a cast strip as pre-band to a heat treatment process and subsequently rolling up or stacking as hot-rolled strip. The pre-band received after the casting process is exposed to a low protective gas atmosphere in connection with a first process for homogenizing the structure, through holding a temperature at 900-1000[deg] C, reducing the temperature to 200[deg] C or through increasing the temperature to 250[deg] C. The pre-band is subjected after the first homogenization process to a further heat treatment through holding the temperature at 880-940[deg] C. The method comprises subjecting a cast strip as pre-band to a heat treatment process and subsequently rolling up or stacking as hot-rolled strip. The pre-band received after the casting process is exposed to a low protective gas atmosphere in connection with a first process for homogenizing the structure, through holding a temperature at 900-1000[deg] C, reducing the temperature to 200[deg] C or through increasing the temperature to 250[deg] C. The pre-band is subjected after the first homogenization process to a further heat treatment through holding the temperature at 880-940[deg] C, through reducing the temperature to 50[deg] C or through increasing the temperature to 50[deg] C. The pre-band is subjected to a hot rolling process and subjected to a thickness reduction of smaller than 49%. The pre-band is subjected to a second process for homogenization and/or for recrystallization of the structure through holding the temperature at 700-900[deg] C, through reducing the temperature to 100[deg] C or through increasing the temperature to 50[deg] C. The casting process is decoupled by rolling process. The carrier speed of the pre-band is influenced by a mass flow control unit. The pre-band is subjected before hot rolling to a second heat treatment through holding the temperature at 880-940 [deg] C, through reducing the temperature to 50[deg] C or through increasing the temperature to 50[deg] C. The pre-band is hot-rolled after the second heat treatment. The pre-band is subjected after the hot-rolling to a second homogenization process for recrystallization of the pre-band in the edge area, through holding the temperature of 700-900[deg] C, through reducing the temperature to 100[deg] C or through increasing the temperature to 50[deg] C. The pre-band after the second homogenization process is passed to a separation device synchronized with the transport speed of the pre-band and is subsequently wrapped or stacked as hot-band. An independent claim is included for a production plant for continuous or discontinuous production of hot rolled strips from steel.

Description

The The invention relates to a process for continuous and discontinuous Producing hot-rolled strips of cast metal, in particular steel, having the features of the preamble of claim 1.

Further The invention relates to a production plant for implementation the method according to the features of the preamble of claim 9th

With a known method for horizontal strip casting is It is possible to melt different types of steel close to the final dimensions of less than 20 mm strip thickness. It can in particular lightweight steels with a high proportion of C, Mn, Al and Si are advantageously made.

So is from the document EP 1 047 510 B1 a production method for producing hot rolled thin flat products known. Thereafter, in a horizontal strip casting plant, molten steel is poured close to the final dimensions in a range of 5 mm to 18 mm strip thickness and cooled under the protective gas atmosphere before it reaches the single-storey roughing line.

The Pre-rolled hot strip is subordinated in one of the suburban road Device optionally controlled cooled, heated or maintained at temperature and the edges of the hot strip are reheated.

Of the single-storey Vorstraße follow a mehrgerüstige Prefabricated street, an exit roller table with a device for cooling the hot strip and upstream and downstream Winding machines for winding the hot strip.

The Roll temperature in front of the multi-stand finishing mill can through the arranged behind the roughing device for cooling, heating or maintaining the temperature of the hot strip either in austenite or ferrite or in the transition region be selectively adjusted from austenite to ferrite.

From the document WO 2006/066551 A1 Furthermore, a method for producing hot strips of lightweight steel is known, which is particularly well cold deep drawable and having as main elements Fe, Mn, Si and Al. The pre-band produced by tape casting first passes through a device under protective gas for homogenization in connection with optionally holding the temperature, cooling or heating. Thereafter, the pre-strip is subjected to at least one pass hot rolling process with a Gesamtumformungsgrad of at least 50%. After the last stitch, the hot strip is cooled and rewound.

In Dependence of the ratio of pouring Rolling speed is the hot rolling process inline or decoupled.

The Homogenization zone is about a temperature compensation the area of the hot strip and a voltage drop inside effect of the hot strip, regardless of whether the temperature level held, raised or lowered.

The Question whether the rolling process inline or decoupled from the casting process It should be done essentially from the different speeds when casting and rolling made dependent, where also the recrystallization behavior of the material of importance is.

at the casting process is a direct connection of the material in the liquid phase in the field of melt application and the continuing process steps of the frozen Material given over the casting belt.

The Casting belt is transported via a transport line for further processing fed. The further process steps can be: straightening, rolling, cutting and winding (reeling, coiling). Through these and other components of a casting machine can there are train and mass flow fluctuations in the casting belt. These disturbances put themselves in the direction of the liquid It can lead to casting defects and to the negative influence on the casting belt, such as Example thickness variations, overflows, edge constrictions and belt or stall.

It Object of the invention, a method for producing hot strip on a strip casting line and a strip casting line further develop with a winding device or stacking device in such a way that the process steps following the casting process no negative influences on the casting belt to be produced in terms of its quality and material properties have and that the casting tape after the casting process in predetermined size units, which are transportable or storable, such. B. stacked sheets or Bundles (coils), is divisible.

The The object is achieved by the features the independent claims 1 and 8 solved.

Accordingly, according to the characterizing features of claim 1, the Vorband produced by tape casting for homogenization of the microstructure undergoes a under inert gas At mosphäre standing first homogenization zone in conjunction with an optional holding the temperature of the pre-strip, reducing the temperature or increasing the temperature, driver, looper, driver error. Subsequently, the pre-band passes through a temperature adjusting device to selectively maintain the temperature of the pre-strip, to reduce the temperature of the pre-strip or to increase the temperature of the pre-strip. In the further course, the preliminary strip is subjected to a reduction in thickness of less than 49% in an at least one pass hot rolling process. Subsequently, the pre-strip passes through a second homogenization zone before it is separated as a hot strip from the incoming pre-strip.

In the first homogenization zone, an argon / CO ₂ nitrogen mixture is used as the inertizing gas. In the first homogenization zone, maintaining the temperature in the range of 900-1000 ° C, reducing the temperature by 200 ° C, and raising the temperature by 250 ° C.

In order to the material can be bent into a coil, it must be suitable Microstructures possess that deformation when occurring Allow tensile and compressive stress.

These Microstructural properties can be defined by the at least one Rolling with one pass up to a degree of deformation of 49% to reach.

By This forming process is initiated recrystallization of the material. In the subsequent second homogenization zone experiences the now obtained hot strip at least in the edge regions followed recrystallization, at a maintained temperature of Hot strip, at a comparatively reduced temperature or at a comparatively higher temperature.

In the second homogenization zone downstream of the first rolling stand The material can recrystallize and it can thus tensile and compressive stresses take up. This procedure of recrystallization is suitable especially in lightweight steels, the u. a. a very can have a large solidification interval, that is, a more or less large "temperature window" from the beginning the solidification from the melt until complete solidification form and dependent on zero strength and zero toughness temperatures have.

After this the precursor has passed through the second homogenization zone the hot strip of a separator with the rolling or conveyor belt speed synchronized working speed supplied with predetermined length cut in the opening band and in one Winding machine wound into a coil.

Of the Process for cutting the hot strip can also already directly after the hot strip has left the second homogenization zone take place, in which case the cut to length hot strip over suitable transport facilities are guided in a stacking system and is stacked there in the form of plates.

In Embodiment of the method according to the invention the casting process is decoupled from the rolling process.

In order to has the advantage that on the one hand, the casting speed depending on the course of the solidification process of Melt can be selected and that on the other hand, the hot rolling process at a defined hot-rolled strip temperature until reaching a given degree of deformation can be done.

In further embodiment of the method according to the invention becomes after the first process for the homogenization of the microstructure the transport speed of the pre-strip by means of a mass flow control unit affected. This will prevent interference the subsequent processes within the manufacturing process negatively influence the casting process and the casting belt, and, for example, to thickness variations, to overflows, to edge constrictions and to belt or stall can come.

To the features of claim 9 is the production plant for carrying out the inventive Method of a known casting machine, the a first homogenization zone under a protective gas atmosphere for influencing the microstructure of the cast pre-strip is subordinate, in which the temperature of the Vorbandes optional held, reduced or increased.

Of the first homogenization zone is a first temperature adjustment device for optionally maintaining the temperature of the pre-strip, reducing it downstream of the temperature or for increasing the temperature.

As seen in the transport direction of the pre-strip, the first temperature adjusting device, with a mass flow control device between a first and second pre-belt conveyor element, is followed by a second temperature adjusting device in which the casting belt is brought to a suitable rolling temperature, optionally by maintaining the temperature of the casting belt. by reducing the temperature or by raising the temperature.

Of the second temperature adjusting device is a first rolling stand downstream, in which with at least one stitch the opening band with the suitable temperature of a reduction in thickness of less than 49% is subjected. In a downstream of the first rolling mill second homogenization zone, the pre-band is now called hot strip at a temperature of 700-900 ° C a Rekristallisa tion, subjected in particular in the edge regions of the hot strip, so that the material tensile or compressive forces as well as plastic Deformations that occur during winding or stacking, without impairment can take the microstructure.

After all the second homogenization zone is followed by a separator, the one with the transport speed of the hot strip conveyor synchronized working speed is operated. In the separator the equipment is continuously tapered and hot rolled Hot rolled strip wound after cutting or stacked as plates. In a further embodiment of the invention Production plant is the first temperature adjusting device one formed from a dancer roller or a loop lifter Downstream of mass flow control unit. The mass flow control unit is, seen in the transport direction of the Vorbandes, between a first pre-belt conveyor element and a second pre-belt conveyor element classified.

Of Another is in an embodiment of the invention in front of the rolling stand a second temperature adjusting device arranged in the Vorband is brought to a suitable rolling temperature, so that the Vorband an at least one stitch having hot rolling process can be subjected, so that the Vorband then as a hot strip a Forming degree of less than 49% of the total conversion has.

After all is the separator in an embodiment of the invention, a winding or stacking device downstream, in which the hot strip to a Bund (coil) wound or stored as individual plates.

Further Features and advantages of the invention will become apparent from the following Description of the embodiment shown in the drawing. In the drawing shows:

1 schematically the production plant for carrying out the method according to the invention for near-net-shape strip casting with winding or stacking device.

The only 1 shows a schematic representation of a production plant according to the invention for carrying out the method according to the invention. The production plant has a casting machine for carrying out the casting process or casting process 1 in the form of a horizontal strip caster, comprising a conveyor in the form of a circulating conveyor belt 2 with two pulleys 3 . 3 ' includes. The casting machine 1 is still with a side seal 4 provided that prevents discontinued melt 5 right and left of the conveyor 2 can flow down. The melt 5 is done by means of a pan 6 to the casting machine 1 transported and flows through a in the bottom of the pan 6 trained opening 7 in a feed vessel 8th , This feed vessel 8th is designed as an overflow vessel.

Not shown in detail are the means for intensive cooling of the underside of the upper run of the conveyor 2 as well as the complete enclosure of the casting machine 1 with appropriate inert gas atmosphere.

After abandonment of the melt 5 on the circulating conveyor belt of the conveyor 2 It comes as a result of the intense cooling to solidification and formation of a casting or pre-strip 9 At the end of the conveyor 2 largely solidified.

For temperature compensation and stress relief closes to the casting machine 1 a first homogenization zone 10 at. This includes a thermally insulated enclosure 11 and a roller table. This first homogenization zone may optionally be used to control the temperature of the casting or pre-strip 9 to keep cooling, or alternatively to heat something up. In particular, it is provided that in this first homogenization zone 10 the casting or pre-band 9 under a blanket gas atmosphere of an argon-CO ₂ nitrogen mixture as the inertizing gas, a first process for homogenizing the texture, optionally by maintaining a temperature at about 900-1000 ° C, reducing the temperature by about 200 ° C, or alternatively raising the temperature is exposed to about 250 ° C.

Subsequently, the casting or pre-strip passes through 9 a first temperature adjusting device 12 and then by means of a first pre-band conveyor element 14 and a second pre-band conveyor element 14 ' by a between the first pre-band conveyor element 14 and the second pre-belt conveyor element 14 ' arranged, formed of dancer roller or looper mass flow control unit 13 a second temperature adjusting device 15 fed. In this second temperature adjustment device 15 will the casting or opening act 9 brought to rolling temperature, before then in a subsequent first rolling stand 16 is subjected to at least one pass a hot rolling process until the casting or pre-strip 9 has a degree of deformation of less than 49% of the total conversion. In this second temperature adjustment device 15 becomes the casting or pre-band 9 optionally maintained at a temperature of about 880-940 ° C, reduced to a temperature of about 50 ° C, or alternatively the temperature increased by about 50 ° C. After passing through the first rolling stand 16 becomes the casting or pre-band 9 then a second homogenization zone 17 supplied in which the casting or pre-strip 9 a second process for homogenization, in particular recrystallization of the microstructure is subjected. This happens because, optionally, the temperature of the casting or pre-strip 9 in the second homogenization zone 17 is kept at a temperature of about 700-900 ° C, the temperature is reduced by about 100 ° C or the temperature is raised by about 50 ° C. Following to the second homogenization zone 17 happens the casting or pre-band 9 then a synchronized with the transport or belt speed separator 18 in the form of a pair of scissors and then as finished rolled and from the casting or pre-band 9 separated hot strip of a winding device 19 or a stacker 20 fed.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1047510 B1 [0004]
• WO 2006/066551 A1 [0008]

Claims (14)

Process for the continuous or discontinuous production of hot-rolled strips of cast metal, in particular steel, according to which the cast strip is subjected as a preliminary strip at least a heat treatment process and subsequently wound or stacked as a hot strip, characterized in that the received after the casting process Vorband an atmosphere under protective gas in connection with a first process for homogenizing the microstructure, by selectively maintaining a temperature at about 900-1000 ° C, by reducing the temperature by about 200 ° C or by raising the temperature by about 250 ° C, the pre-band is exposed after the first homogenization process is subjected to at least one further heat treatment by selectively maintaining the temperature at 880-940 ° C, by reducing the temperature by about 50 ° C or by raising the temperature by about 50 ° C, the precursor is subsequently subjected to at least one of to have a stitch A hot rolling process is performed, wherein the pre-strip is subjected to a reduction in thickness of less than 49%, that the pre-strip then a second process for homogenization or recrystallization of the microstructure, by optionally maintaining the temperature at about 700-900 ° C, by reducing the temperature is subjected to about 100 ° C or by raising the temperature by about 50 ° C, and that the pre-strip is subsequently passed through a separating device synchronized with the transport or belt speed and separated from the pre-strip as rolled hot strip. Method according to claim 1, characterized in that that the casting process is decoupled from the rolling process. Method according to one of the preceding claims, characterized in that the transport speed of the pre-strip is influenced by a mass flow control unit. Process according to claims 1 to 3, characterized characterized in that the pre-strip before hot rolling a second Heat treatment by optionally holding the temperature at about 880-940 ° C, by reducing the temperature by about 50 ° C or by raising the temperature is subjected to about 50 ° C. Process according to claims 1 to 4, characterized characterized in that the pre-band after the second heat treatment is rolled hot. Process according to claims 1 to 5, characterized characterized in that the pre-strip after hot rolling a second Homogenization process, in particular for the recrystallization of Vorbandes in the edge areas, by optionally holding the temperature at about 700-900 ° C, by reducing the temperature by about 100 ° C or by raising the temperature about 50 ° C, is exposed. Process according to claims 1 to 6, characterized characterized in that the pre-band after the second homogenization process as a hot strip one with the transport speed of the Vorbandes synchronized separator happens and the pre-band as a hot strip subsequently wound or stacked. Production plant for carrying out the method according to one or more of claims 1 to 7, with at least one casting machine ( 1 ) for producing a casting or preliminary strip ( 9 ) of predetermined thickness, with at least one conveyor ( 2 ) for transporting the casting belt, with at least one homogenization zone ( 10 ), in which the temperature is maintained, reduced or increased in order to influence the microstructure of the casting or pre-strip, with at least one further temperature zone in which the temperature is maintained, reduced or increased, with at least one first roll stand ( 16 ) to achieve a partial transformation of the pre-strip ( 9 ), with at least one separating device ( 18 ) and with at least one winding or stacking device ( 19 ; 20 ), characterized in that the casting machine ( 1 ) a first homogenization zone under a protective gas atmosphere ( 10 ), in which the temperature is optionally kept, reduced or increased, that the first homogenization zone ( 10 ) a temperature adjusting device ( 15 ) for selectively holding the temperature, for reducing the temperature or for increasing the temperature downstream of the temperature adjusting device ( 15 ) a first rolling stand ( 16 ) is subordinated, in which is subjected to at least one stitch the Vorband a reduction in thickness of less than 49% that the rolling stand ( 16 ) a second homogenization zone ( 17 ), in which the temperature is optionally kept, reduced or increased in order to obtain a recrystallization of the hot strip at least in the edge regions, and that the second homogenization zone ( 17 ) a separating device ( 18 ) whose working speed is at the speed of the conveyor ( 2 ) is synchronized, and in which the pre-rolled Vorband ( 9 ) is separated as hot strip from the opening strip. Production plant according to claim 8, characterized that the casting process is decoupled from the rolling process. Production plant according to claim 8 or 9, characterized in that the first homogenization zone ( 10 ) a mass flow control unit formed from dancer roll or looper 13 ) is subordinate. Production plant according to one of claims 8-10, characterized in that a mass flow control unit ( 13 ), in the transport direction of the Vorbandes ( 9 ), between a first crop conveyor element ( 14 ) and a second pre-band conveying element ( 14 ) is arranged. Production plant according to one of claims 8-11, characterized in that in the transport direction of the strip of the first homogenization zone ( 10 ) a first temperature adjustment device ( 12 ) and a mass flow control unit ( 13 ), wherein the mass flow control unit of the second temperature control device ( 15 ) is connected upstream. Production plant according to claim 12, characterized in that between the first temperature adjusting device ( 12 ) and the mass flow control unit ( 13 ) and / or between the mass flow control unit ( 13 ) and the second temperature adjustment device ( 15 ) a conveying element ( 14 . 14 ' ) is arranged. Production plant according to one of claims 8-13, characterized in that the separating device ( 18 ) a winding device ( 19 ) or a stacking device ( 20 ) is subordinate.