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EP0563786A1 - Method of casting high-alloy steels on bow-type continuous casting plant - Google Patents

Method of casting high-alloy steels on bow-type continuous casting plant Download PDF

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Publication number
EP0563786A1
EP0563786A1 EP93104905A EP93104905A EP0563786A1 EP 0563786 A1 EP0563786 A1 EP 0563786A1 EP 93104905 A EP93104905 A EP 93104905A EP 93104905 A EP93104905 A EP 93104905A EP 0563786 A1 EP0563786 A1 EP 0563786A1
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EP
European Patent Office
Prior art keywords
strand
straightening
steel
casting
bending device
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
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EP93104905A
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German (de)
French (fr)
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EP0563786B1 (en
Inventor
Hans-Georg Dr.-Ing. Rosenstock
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IBVT INGENIEURBUERO FUER VERFAHRENSTECHNIK GMBH
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Ibvt Ingenieurbuero fur Verfahrenstechnik GmbH
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16Controlling or regulating processes or operations
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12Accessories for subsequent treating or working cast stock in situ
    • B22D11/124Accessories for subsequent treating or working cast stock in situ for cooling
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12Accessories for subsequent treating or working cast stock in situ
    • B22D11/128Accessories for subsequent treating or working cast stock in situ for removing
    • B22D11/1287Rolls; Lubricating, cooling or heating rolls while in use
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16Controlling or regulating processes or operations
    • B22D11/20Controlling or regulating processes or operations for removing cast stock

Definitions

  • the invention relates to a method for casting high-alloy steels on circular arc continuous casting plants, the steel melt being passed through a water-cooled mold, from which a surface solidified steel strand emerges, which is cooled under the action of coolants for further solidification, deflected in a circular manner via support rollers and then over a multi-point bending device is bent back from the circular arc into the horizontal.
  • Highly alloyed steels such as austenitic or ferritic chromium-nickel, nickel-chromium or 13% chromium steels, to which molybdenum, vanadium, tungsten, silicon or aluminum are added as a further alloy component, depending on use and stress, and which are and acid-resistant, used as heat-resistant or scaling-resistant steels and tool steels, solidify without transformation:
  • carbides and other phases separate during solidification, which differ considerably in their composition from the basic matrix metallurgically in the structure of the steel alloy and are unfavorable affect toughness and resilience. Stresses that occur during solidification, cooling and hot working, especially during the straightening of these steels, easily lead to tears between the interfaces of the crystals.
  • the invention is therefore based on the object of specifying a method which permits the fault-free production of high-alloy steels on such continuous casting plants, which takes into account the use of all steel brands and lot sizes occurring in the stainless steel sector are flexible, care being taken in the course of the process that the steel matrix can absorb the stresses that occur and surface cracks can be avoided.
  • the strand temperatures are determined over the strand cross-section in the area of the multi-point bending device and, taking into account the high-temperature material properties determined from hot-tensile tests in the form of stress-strain curves, the guide force for the minimum deformation is calculated in order to to bend the steel strand in the multi-point bending device from the circular arc to the horizontal.
  • gentle straightening operations which are matched to the respective steel brand, the format to be cast and the casting speed or strand cooling, are carried out when bending the arcuate steel strand produced on circular arc casting machines in the area of a multi-point bending device in order to better control the dreaded surface crack formation in the strands .
  • the invention proposes to calculate the straightening force for the straight bending of the bent steel strand, with the stipulation to limit the stresses that occur in such a way that the steel matrix can absorb them without separations.
  • the high-temperature material properties obtained in this way are assigned to the strand temperatures which, according to the invention, are determined in the area of the reference point via the strand cross-section, for example by measuring the strand surface temperature and calculating the temperature profile from the strand cross-section.
  • the straightening force required to bend the steel strand from the circular arc to the horizontal using a multi-point bending device is calculated from these specifications, taking into account the casting conditions and the strand formats.
  • the figure shows a block diagram from which it can be seen in what way the high-temperature properties of a steel can be used to determine the required straightening force and straightening work which can be influenced via the straightening temperatures and thus regulated by the casting conditions and the strand cooling.
  • An advantageous development of the invention provides a target-actual value comparison of the straightening force, with the aid of which the casting speed and / or the strand cooling is controlled, as is also shown in the figure. If the required straightening force rises above the calculated limit value for the required deformation effort, the straightening temperature can be increased accordingly by increasing the casting speed and / or adapting the strand cooling and thus the required straightening force will be lower and adapted to the limit value derived from the material properties.
  • the casting speed must be reduced and / or the strand cooling must be adjusted accordingly. This lowers the target temperature and does not exceed the minimum deformation required to achieve a straight strand.
  • the method is not limited to straightening cast steel strands that have already completely solidified in the bending device.
  • the method according to the invention can also be applied without restriction to the straightening of partially solidified strands which have a solidified edge zone and a still liquid core area.
  • the strength of the solidified edge zone in the area of the straightening point is determined using the described method and used to calculate the required straightening force or straightening work.
  • Straightening partially solidified steel strands requires less straightening deformation than completely solidified strands, so that the deformation can be carried out more gently overall. This also has an advantageous effect when straightening high-temperature steels on the system parts of the multi-point bending device which are exposed to lower loads.
  • EP-OS 0 315 043 for measuring the rolling force on rolling mill rolls is advantageous, which can be easily accepted and which compares the actually existing force carries out with the maximum permissible force, which is a claim of the described inventive method.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)

Abstract

The invention relates to a method of casting high-alloy steels on bow-type continuous casting plant, the molten steel being passed through a water-cooled mould from which a superficially solidified steel strand emerges and is cooled for further solidification by subjecting it to coolants, it is deflected in an arc over supporting rollers and is then bent back again out of the arc into the horizontal by a multi-point bending device. The invention envisages calculating the straightening force for the straightening of the arcuate steel strand from the high-temperature properties of the steel determined in hot tensile tests and the temperature profiles of the steel strand calculated from surface temperatures. A setpoint/actual value comparison of the calculated and the actually measured straightening force is used to regulate the casting conditions and cooling in such a way that the steel strand is treated in the gentlest manner possible in the straightening process, allowing surface cracks to be largely eliminated.

Description

Die Erfindung betrifft ein Verfahren zum Gießen von höchstlegierten Stählen auf Kreisbogen-Stranggießanlagen, wobei die Stahlschmelze durch eine wassergekühlte Kokille geführt wird, aus der ein oberflächig erstarrter Stahlstrang austritt, der unter Beaufschlagung von Kühlmitteln zur weiteren Erstarrung gekühlt, über Stützrollen kreisförmig umgelenkt und anschließend über eine Mehrpunktbiegeeinrichtung vom Kreisbogen wieder in die Horizontale zurückgebogen wird.The invention relates to a method for casting high-alloy steels on circular arc continuous casting plants, the steel melt being passed through a water-cooled mold, from which a surface solidified steel strand emerges, which is cooled under the action of coolants for further solidification, deflected in a circular manner via support rollers and then over a multi-point bending device is bent back from the circular arc into the horizontal.

Höchstlegierte Stähle, wie die austenitischen oder ferritischen Chrom-Nickel-, Nickel-Chrom- oder 13%igen Chromstähle, denen je nach Einsatz und Beanspruchung noch Molybdän, Vanadin, Wolfram, Silizium oder Aluminium als weitere Legierungskomponente zugesetzt sind, und die als rost- und säurebeständige, als hochwarmfeste oder zunderbeständige Stähle und Werkzeugstähle Verwendung finden, erstarren umwandlungsfrei: Je nach der chemischen Zusammensetzung scheiden sich während der Erstarrung Karbide und andere Phasen aus, die sich metallurgisch im Gefüge der Stahllegierung in ihrer Zusammensetzung von der Grundmatrix erheblich unterscheiden und sich ungünstig auf Zähigkeit und Formänderungsvermögen auswirken. Spannungen, die während des Erstarrens, Erkaltens und Warmumformens, insbesondere während des Richtens dieser Stähle auftreten, führen leicht zu Aufreißungen zwischen den Grenzflächen der Kristalle.Highly alloyed steels, such as austenitic or ferritic chromium-nickel, nickel-chromium or 13% chromium steels, to which molybdenum, vanadium, tungsten, silicon or aluminum are added as a further alloy component, depending on use and stress, and which are and acid-resistant, used as heat-resistant or scaling-resistant steels and tool steels, solidify without transformation: Depending on the chemical composition, carbides and other phases separate during solidification, which differ considerably in their composition from the basic matrix metallurgically in the structure of the steel alloy and are unfavorable affect toughness and resilience. Stresses that occur during solidification, cooling and hot working, especially during the straightening of these steels, easily lead to tears between the interfaces of the crystals.

Deshalb gelten diese Stähle als sehr anfällig gegen Oberflächenrisse, und sie lassen sich trotz erheblicher Anstrengungen und Erfolge zur Begrenzung der Spannungspitzen bei der Kühlung und dem Richten in Kreisbogenanlagen nur unter großen Schwierigkeiten abgießen. Diese Stähle werden deshalb bei Erzeugung über Strangguß vornehmlich auf Senkrecht- oder Horizontal-Stranggießanlagen abgegossen. Beide Anlagentypen arbeiten nach Verfahren, die hinsichtlich der Erstarrung des Stahles ohne Rißbildung an der Strangoberfläche optimiert sind, und die ohne das bei Kreisbogenanlagen erforderliche Richten der Stränge auskommen. Allerdings verfügen diese Anlagen nur über ein begrenztes Kapazitätsangebot in t/h.For this reason, these steels are considered to be very susceptible to surface cracks, and despite considerable efforts and successes in limiting the stress peaks during cooling and straightening in circular arc systems, they can only be cast with great difficulty. These steels are therefore mainly poured onto vertical or horizontal continuous casting machines when they are produced using continuous casting. Both types of plant work according to methods that are optimized with regard to the solidification of the steel without crack formation on the strand surface and that do not require the straightening of the strands required in circular arc systems. However, these plants only have a limited capacity in t / h.

Senkrecht-Stranggießanlagen für größere Abmessungen und Leistungen würden dagegen unwirtschaftlich hohe Investitionen erfordern und hätten wegen der für diesen Stahlmarkenbereich geringen Erzeugungsmengen in t/Monat keine ausreichende Auslastung. Deshalb werden höchstlegierte Stähle heute noch aus Losgrößenüberlegungen in vielen Fällen als Schmiedeblöcke oder Walzblöcke abgegossen. Die Erzeugung der Blöcke und ihre Bearbeitung für ihren Einsatz in die nächste Fertigungsstufe und das Verformen sind aufwendig und belasten die Fertigerzeugnisse mit sehr hohen Herstellkosten.Vertical continuous casting plants for larger dimensions and capacities, on the other hand, would require uneconomically high investments and would not have sufficient capacity utilization due to the low production volumes in t / month for this steel brand sector. For this reason, high-alloy steels are still cast in many cases as forging blocks or rolling blocks based on batch size considerations. The production of the blocks and their processing for their use in the next production stage and the shaping are complex and burden the finished products with very high manufacturing costs.

Der Erfindung liegt deshalb die Aufgabe zugrunde, ein Verfahren anzugeben, das die fehlerfreie Erzeugung von höchstlegierten Stählen auf solchen Stranggießanlagen erlaubt, die hinsichtlich des Einsatzes aller im Edelstahlbereich vorkommenden Stahlmarken und Losgrößen flexibel sind, wobei im Verfahrensablauf dafür Sorge getragen wird, daß die Stahlmatrix die auftretenden Spannungen aufnehmen kann und Oberflächenrisse vermieden werden können.The invention is therefore based on the object of specifying a method which permits the fault-free production of high-alloy steels on such continuous casting plants, which takes into account the use of all steel brands and lot sizes occurring in the stainless steel sector are flexible, care being taken in the course of the process that the steel matrix can absorb the stresses that occur and surface cracks can be avoided.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß im Bereich der Mehrpunktbiegeeinrichtung die Strangtemperaturen über den Strangquerschnitt ermittelt werden und unter Berücksichtigung der aus Heißzugsversuchen in Form von Spannungs-Dehnungs-Kurven ermittelten Hochtemperatur-Werkstoffeigenschaften die Richtkraft für die Mindestverformung berechnet wird, die erforderlich ist, um den Stahlstrang in der Mehrpunktbiegeeinrichtung vom Kreisbogen in die Horizontale zurückzubiegen.This object is achieved in that the strand temperatures are determined over the strand cross-section in the area of the multi-point bending device and, taking into account the high-temperature material properties determined from hot-tensile tests in the form of stress-strain curves, the guide force for the minimum deformation is calculated in order to to bend the steel strand in the multi-point bending device from the circular arc to the horizontal.

Eine vorteilhafte Weiterentwicklung der Erfindung ist dadurch gegeben, daß ein Soll-Ist-Wertevergleich der Richtkraft durchgeführt wird und bei Über- oder Unterschreiten des rechnerisch ermittelten Grenzwertes der Richtkraft die Strangtemperatur in der Mehrpunktbiegeeinrichtung durch Erhöhen oder Zurücknehmen der Sekundärkühlung im Rahmen ihrer Steuerungsparameter und weiter durch Erhöhen oder Zurücknehmen der Gießgeschwindigkeit als Steuerungsparameter für die Strangtemperatur gesteigert oder abgesenkt wird.An advantageous further development of the invention is given in that a target-actual value comparison of the straightening force is carried out and if the calculated limit value of the straightening force is exceeded or undershot, the strand temperature in the multi-point bending device by increasing or decreasing the secondary cooling as part of its control parameters and further Increasing or reducing the casting speed as a control parameter for the strand temperature is increased or decreased.

Die mit der Erfindung erzielten Vorteile bestehen insbesondere darin, daß eine moderne Technologie zur Verfügung gestellt wird, die die Erzeugung von rißempfindlichen, höchstlegierten Stählen fehlerfrei und kostengünstig auf den für die Erzeugung von Edelstählen bewährten Kreisbogen-Stranggießanlagen gestattet.The advantages achieved by the invention consist in particular in the fact that a modern technology is made available which enables the production of crack-sensitive, high-alloy steels to be carried out error-free and inexpensively for the production of Proven circular arc continuous casting machines are permitted.

Im folgenden wird die Erfindung näher beschrieben und anhand einer Zeichnung erläutert.The invention is described in more detail below and explained with reference to a drawing.

Das Bestreben, Energie-, Betriebs- und Investitionskosten zu sparen sowie die Qualität der Produkte zu steigern, führte in der Stahlindustrie zur Umstellung von Block- auf Strangguß. Trotz verfeinerter Prozeßsteuerung beim Stranggießen wird bei einer Reihe von Stählen, insbesondere bei den höchstlegierten Stählen, eine fehlerfreie Erzeugung noch nicht sicher beherrscht. Weitere Parameter wichtiger Einflußgrößen müssen zur Optimierung der Fertigung herangezogen werden.In the steel industry, efforts to save energy, operating and investment costs and to improve the quality of the products led to the switch from ingot casting to continuous casting. Despite refined process control in continuous casting, error-free production is not yet reliably mastered in a number of steels, especially the highest-alloy steels. Other parameters of important influencing variables must be used to optimize production.

Erfindungsgemäß ist es vorgesehen, schonende, auf die jeweilige Stahlmarke, das zu gießende Format und die Gießgeschwindigkeit bzw. Strangkühlung abgestimmte Richtoperationen beim Geradebiegen des auf Kreisbogen-Stranggießanlagen erzeugten bogenförmigen Stahlstranges im Bereich einer Mehrpunktbiegeeinrichtung durchzuführen, um die gefürchtete Oberflächenrißbildung in den Strängen besser zu beherrschen. Die Erfindung schlägt vor, die Richtkraft für das Geradebiegen des gebogenen Stahlstranges zu berechnen unter der Vorgabe, die dabei auftretenden Spannungen so zu begrenzen, daß die Stahlmatrix sie ohne Trennungen aufnehmen kann. Einen Beitrag dazu liefern die bekannten Heißzugversuche zur Ermittlung der Hochtemperaturfestigkeits- und - zähigkeitseigenschaften der Stähle, die als Spannungs-Dehnungs-Kurven aufgenommen werden, und deren Kenntnis Hinweise auf den Kraft- und Arbeitsbedarf von Umformeinrichtungen sowie auf die maximal zulässigen Verformungen ohne Werkstoffschädigungen gibt.According to the invention, gentle straightening operations, which are matched to the respective steel brand, the format to be cast and the casting speed or strand cooling, are carried out when bending the arcuate steel strand produced on circular arc casting machines in the area of a multi-point bending device in order to better control the dreaded surface crack formation in the strands . The invention proposes to calculate the straightening force for the straight bending of the bent steel strand, with the stipulation to limit the stresses that occur in such a way that the steel matrix can absorb them without separations. The well-known hot tensile tests to determine the high-temperature strength and toughness properties of the steels, which are recorded as stress-strain curves, and their knowledge provide a contribution to this Forming devices as well as the maximum permissible deformations without material damage.

Die derart gewonnenen Hochtemperatur-Werkstoffeigenschaften werden den Strangtemperaturen zugeordnet, die gemäß der Erfindung im Bereich des Richtpunktes über den Strangquerschnitt ermittelt werden, beispielsweise dadurch, daß die Strangoberflächentemperatur gemessen und daraus das Temperaturprofil über den Strangquerschnitt berechnet wird. Aus diesen Vorgaben wird unter Berücksichtigung der Gießbedingungen und der Strangformate die Richtkraft errechnet, die benötigt wird, um den Stahlstrang vom Kreisbogen über eine Mehrpunktbiegeeinrichtung in die Horizontale zurückzubiegen. In der Figur ist ein Blockdiagramm dargestellt, aus dem entnommen werden kann, in welcher Weise die Hochtemperatureigenschaften eines Stahles zur Ermittlung der über die Richttemperaturen beeinflußbaren und damit durch die Gießbedingungen und die Strangkühlung regelbare, erforderliche Richtkraft und Richtarbeit herangezogen werden können.The high-temperature material properties obtained in this way are assigned to the strand temperatures which, according to the invention, are determined in the area of the reference point via the strand cross-section, for example by measuring the strand surface temperature and calculating the temperature profile from the strand cross-section. The straightening force required to bend the steel strand from the circular arc to the horizontal using a multi-point bending device is calculated from these specifications, taking into account the casting conditions and the strand formats. The figure shows a block diagram from which it can be seen in what way the high-temperature properties of a steel can be used to determine the required straightening force and straightening work which can be influenced via the straightening temperatures and thus regulated by the casting conditions and the strand cooling.

Eine vorteilhafte Weiterbildung der Erfindung sieht einen Soll-Ist-Wertevergleich der Richtkraft vor, mit dessen Hilfe eine Steuerung der Gießgeschwindigkeit und/oder der Strangkühlung vorgenommen wird, wie ebenfalls in der Figur gezeigt wird. Steigt die benötigte Richtkraft über den berechneten Grenzwert für den benötigten Verformungsaufwand hinaus an, kann durch die Erhöhung der Gießgeschwindigkeit und/oder die Anpassung der Strangkühlung die Richttemperatur entsprechend gesteigert werden und damit die benötigte Richtkraft niedriger ausfallen und dem aus den Werkstoffeigenschaften hergeleiteten Grenzwert angepaßt werden.An advantageous development of the invention provides a target-actual value comparison of the straightening force, with the aid of which the casting speed and / or the strand cooling is controlled, as is also shown in the figure. If the required straightening force rises above the calculated limit value for the required deformation effort, the straightening temperature can be increased accordingly by increasing the casting speed and / or adapting the strand cooling and thus the required straightening force will be lower and adapted to the limit value derived from the material properties.

Wird dagegen die benötigte Richtkraft im Soll-Ist-Wertevergleich unterschritten, muß die Gießgeschwindigkeit zurückgenommen und/oder die Strangkühlung entsprechend angepaßt werden. Damit wird die Richttemperatur abgesenkt und die für das Erzielen eines geraden Stranges erforderliche Mindestverformung nicht überschritten.If, on the other hand, the required directional force is undershot in the target / actual value comparison, the casting speed must be reduced and / or the strand cooling must be adjusted accordingly. This lowers the target temperature and does not exceed the minimum deformation required to achieve a straight strand.

Es liegt im Sinne der Erfindung, daß das Verfahren nicht allein auf das Richten von gegossenen Stahlsträngen beschränkt bleibt, die in der Biegeeinrichtung bereits vollständig erstarrt sind. Das erfindungsgemäße Verfahren läßt sich ohne jegliche Einschränkung auch auf das Richten von teilerstarrten Strängen anwenden, die eine erstarrte Randzone und einen noch flüssigen Kernbereich aufweisen. In diesem Fall wird die Festigkeit der erstarrten Randzone im Bereich des Richtpunktes nach dem beschriebenen Verfahren ermittelt und für die Errechnung der erforderlichen Richtkraft bzw. Richtarbeit herangezogen. Das Richten von teilerstarrten Stahlsträngen erfordert eine geringere Richtverformung als vollständig erstarrte Stränge, so daß die Verformung insgesamt schonender erfolgen kann. Dies wirkt sich auch vorteilhaft beim Richten von hochwarmfesten Stählen auf die Anlagenteile der Mehrpunktbiegeeinrichtung aus, die geringeren Beanspruchungen ausgesetzt sind.It is within the meaning of the invention that the method is not limited to straightening cast steel strands that have already completely solidified in the bending device. The method according to the invention can also be applied without restriction to the straightening of partially solidified strands which have a solidified edge zone and a still liquid core area. In this case, the strength of the solidified edge zone in the area of the straightening point is determined using the described method and used to calculate the required straightening force or straightening work. Straightening partially solidified steel strands requires less straightening deformation than completely solidified strands, so that the deformation can be carried out more gently overall. This also has an advantageous effect when straightening high-temperature steels on the system parts of the multi-point bending device which are exposed to lower loads.

Die Auslegung und Steuerung der Stranggießanlage muß diesen Anforderungen Rechnung tragen. Es müssen deshalb in Abhängigkeit von der Stahlmarke und dem zu gießenden Format unterschiedliche Gießgeschwindigkeiten und Regelungsmöglichkeiten der Strangkühlung eingestellt werden können, und es ist dafür Sorge zu tragen, daß Erstarrungsverhalten, entstehende Spannungszustände und die Wärmeabfuhr aufeinander abgestimmt und geregelt werden können. Mit dieser Regelung werden die Stahlstränge auf die denkbar schonendste Weise beim Richten behandelt, so daß Oberflächenrisse weitgehend ausgeschlossen werden können.The design and control of the continuous caster must take these requirements into account. Depending on the steel brand and the format to be cast, different casting speeds and control options for strand cooling must therefore be set, and care must be taken to ensure that solidification behavior, resulting stress conditions and heat dissipation can be coordinated and regulated with one another. With this regulation, the Steel strands treated in the most gentle way possible during straightening, so that surface cracks can be largely excluded.

Zur Ermittlung der Richtkraft, die im Bereich der Mehrpunktbiegeeinrichtung auf den Stahlstrang übertragen wird, bietet sich vorteilhaft das in der EP-OS 0 315 043 beschriebene Verfahren zur Walzkraftmessung an Walzwerkswalzen an, das ohne weiteres übernommen werden kann und das einen Vergleich der tatsächlich vorliegenden Kraft mit der maximal zulässigen Kraft durchführt, der ein Anspruch des beschriebenen, erfindungsgemäßen Verfahrens ist.To determine the straightening force which is transferred to the steel strand in the area of the multi-point bending device, the method described in EP-OS 0 315 043 for measuring the rolling force on rolling mill rolls is advantageous, which can be easily accepted and which compares the actually existing force carries out with the maximum permissible force, which is a claim of the described inventive method.

Claims (2)

Verfahren zum Gießen von höchstlegierten Stählen auf Kreisbogen-Stranggießanlagen, wobei die Stahlschmelze durch eine wassergekühlte Kokille geführt wird, aus der ein oberflächig erstarrter Stahlstrang austritt, der unter Beaufschlagung von Kühlmitteln zur weiteren Erstarrung gekühlt, über Stützrollen kreisförmig umgelenkt und anschließend über eine Mehrpunktbiegeeinrichtung vom Kreisbogen wieder in die Horizontale zurückgebogen wird, dadurch gekennzeichnet, daß im Bereich der Mehrpunktbiegeeinrichtung die Strangtemperaturen über den Strangquerschnitt ermittelt werden und unter Berücksichtigung der aus Heißzugversuchen in Form von Spannungs-Dehnungs-Kurven ermittelten Hochtemperatur-Werkstoffeigenschaften die Richtkraft für die Mindestverformung berechnet wird, die erforderlich ist, um den Stahlstrang in der Mehrpunktbiegeeinrichtung vom Kreisbogen in die Horizontale zurückzubiegen.Process for casting high-alloy steels on circular arc continuous casting plants, in which the molten steel is passed through a water-cooled mold, from which a surface-solidified steel strand emerges, which is cooled by further cooling under the action of coolants, deflected in a circular manner by support rollers and then by a multi-point bending device from the circular arc is bent back into the horizontal, characterized in that the strand temperatures are determined over the strand cross-section in the area of the multi-point bending device and taking into account the high-temperature material properties determined from hot tensile tests in the form of stress-strain curves, the guide force for the minimum deformation is calculated, which is required is to bend the steel strand in the multi-point bending device from the circular arc to the horizontal. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß ein Soll-Ist-Wertevergleich der Richtkraft durchgeführt wird und bei Über- oder Unterschreiten des rechnerisch ermittelten Grenzwertes der Richtkraft die Strangtemperatur in der Mehrpunktbiegeeinrichtung durch Erhöhen oder Zurücknehmen der Sekundärkühlung im Rahmen ihrer Steuerungsparameter und weiter durch Erhöhen oder Zurücknehmen der Gießgeschwindigkeit als Steuerungsparameter für die Strangtemperatur gesteigert oder abgesenkt wird.A method according to claim 1, characterized in that a target-actual value comparison of the straightening force is carried out and if the calculated limit value of the straightening force is exceeded or undershot, the strand temperature in the multi-point bending device by increasing or decreasing the secondary cooling as part of its control parameters and further by increasing it or reducing the casting speed as a control parameter for the strand temperature is increased or decreased.
EP93104905A 1992-03-31 1993-03-25 Method of casting high-alloy steels on bow-type continuous casting plant Expired - Lifetime EP0563786B1 (en)

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JP (1) JP2635906B2 (en)
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EP0650790B2 (en) * 1993-10-29 2013-10-16 DANIELI & C. OFFICINE MECCANICHE S.p.A. Method for thermal surface treatment in a continuous casting machine
US6789602B2 (en) 2002-02-11 2004-09-14 Commonwealth Industries, Inc. Process for producing aluminum sheet product having controlled recrystallization
ITMI20021512A1 (en) * 2002-07-10 2004-01-12 Danieli Off Mecc METHOD FOR THE ADJUSTMENT OF THE TEMPERATURE OF THE TAPE IN A CONTINUOUS CASTING METAL TAPE SYSTEM AND RELATED ACTUATING DEVICE

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EP0563786B1 (en) 1998-11-11
ATE173188T1 (en) 1998-11-15
KR930019305A (en) 1993-10-18
DK0563786T3 (en) 1999-07-26
JPH06126410A (en) 1994-05-10
US5454417A (en) 1995-10-03
KR960008876B1 (en) 1996-07-05
DE4210495C1 (en) 1993-04-15
JP2635906B2 (en) 1997-07-30
ES2123583T3 (en) 1999-01-16

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