EP0013331A1 - Method for making profiles and the use of a fine grained steel for profiles - Google Patents

Method for making profiles and the use of a fine grained steel for profiles Download PDF

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Publication number
EP0013331A1
EP0013331A1 EP79104823A EP79104823A EP0013331A1 EP 0013331 A1 EP0013331 A1 EP 0013331A1 EP 79104823 A EP79104823 A EP 79104823A EP 79104823 A EP79104823 A EP 79104823A EP 0013331 A1 EP0013331 A1 EP 0013331A1
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Prior art keywords
temperature
profiles
profile
steel strip
sheet
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EP79104823A
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German (de)
French (fr)
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EP0013331B1 (en
Inventor
Heinz Gross
Friedhelm Retzlaff
Friedrich Reith
Karl Heinz Schlusnus
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Hoesch Werke AG
Hoesch AG
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Hoesch Werke AG
Hoesch AG
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/02—Hardening by precipitation
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2261/00—Machining or cutting being involved
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling

Definitions

  • the invention relates to a method according to the preamble of claim 1.
  • the aim is the use of profiles with high strength characteristics as supplied for use as structural parts when high B auteilfesttechniken are to be achieved at low weights, for example for vehicle parts, hydraulic cylinder, steel high parts or when high loads are inevitably in the structural limitation of the dimensions as eg for oil field pipes for drilling technology.
  • the pipes In practice, these conditions have limited the yield strength of the profiles to about 5oo N / mm2 and the tensile strength to about 65o N / mm2 when manufacturing, for example, welded pipes. Accordingly, the pipes must be formed from strips or sheets of soft grades with a yield strength of up to 5oo N / mm2, welded and, if the demands on the yield strength are higher, liquid-hardened and tempered, ie tempered.
  • the invention has for its object to provide a method of the type mentioned, by means of which the disadvantages of the known methods avoided and in a relatively simple and therefore cost-effective manner while avoiding expensive remuneration a manufacture of high-strength profiles, in particular closed tube profiles with a yield strength of more than 5 0 o N / mm2, a tensile strength of more than 6 00 N / mm and high toughness, including the required mechanical welding.
  • a precipitation-hardenable fine-grain steel is preferably understood to mean a steel which has a composition of Remainder has iron and usual impurities and - which in the finished state has an ASTM grain size of finer 6.
  • the überalternde artificial aging of the precipitation hardenable fine-grain steel is done in which no grain refinement during cooling, preferably made of the above the A 1 temperature at 85o to 75 0 ° C to a collar gehaspelten steel strip.
  • a corresponding microstructure is achieved according to the invention in sheet metal by furnace cooling, by means of which radiation and convection are prevented, from the rolling heat. Both with the rolled steel strip As with steel sheet, it is essential that the slowed down cooling is carried out up to a temperature of 400 ° C., while the subsequent cooling down to room temperature is carried out in any way.
  • An open profile produced cold in this way is preferably welded to a closed tubular profile before further treatment according to the invention.
  • the open or closed profiles produced according to the invention are subsequently subjected to a solution annealing above the A C3 temperature with subsequent cooling in order to bring about precipitation hardening, which is also referred to as particle hardening and fine grain hardening.
  • the type of cooling should be used to achieve the formation of finely divided carbides, nitrides and carbonitrides with simultaneous fine grain formation.
  • the temperature of the solution heat treatment is advantageously selected to be the temperature at which the stretch reduction of the starting pipe is started, ie the piercing temperature. A separate solution annealing is then no longer required in these reduced-stretch pipes, since the cooling following the solution annealing takes place during the reduction in stretch or immediately afterwards.
  • Balance iron and unavoidable impurities after hot rolling the band preferably W armbreitband without intermediate cooling after the last W alzstich at a temperature of about 750 ° C into a coil (coil) is coiled and cooled in still air to 400 ° C.
  • the natural heat storage capacity of the Federal is used for the armauslagern überalternde W, in which the precipitation and coagulation of the carbides, nitrides and carbonitrides largely proceed to completion while avoiding a grain refinement. Further cooling to room temperature is done in any way.
  • the hot broadband has a yield strength of 455 N / mm 2 and a tensile strength of 65o N / mm 2 after it has completely cooled to room temperature or has aged.
  • the hot wide strip is then cut into strips, if necessary trimmed and subsequently cold-formed, in the present example in a continuous process formed into a slotted tube, which is welded to a tube with a diameter of 159 mm by means of a high-frequency welding device.
  • This tube is heated to a temperature of about 1 0 3 0 ° C and with this temperature as the piercing temperature in a stretch reduction process to the ge desired diameter of 6 0 , 3 mm rolled.
  • the finished tube is cooled on a cooling bed in still air to room temperature.
  • the coarse carbides, nitrides and carbonitrides are dissolved in the steel while the tube is being heated or held to the rolling temperature and are finely distributed during cooling or after the rolling with simultaneous formation of fine grains.
  • the finished tube has after this treatment, a yield strength of 648 N / mm 2 and a Z ug strength of 845 N / mm to 2.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Forging (AREA)

Abstract

Verfahren zum Herstellen von Profilen mit einer Streckgrenze von >= 500 N/mm², einer Zugfestigkeit von >= 600 N/mm² und hoher Zähigkeit aus warmgewalztem Stahlband oder -blech mit folgenden Verfahrensschritten; a) das aus einem ausscheidungshärtbaren Feinkornstahl bestehende Stahlband oder -blech wird aus der Walzhitze nach dem letzten Walzstich von einer Endwalztemperatur oberhalb der A1-Temperatur auf eine Temperatur von etwa 400°C überalternd warmausgelagert und anschießend auf Raumtemperatur abgekühlt; b) das Stahlband oder -blech wird zu einem offenen Profil kaltverarbeitet; c) das Profil wird einer Lösungsglühung zur Auflösung der groben Ausscheidungen unterworfen und anschließend zur Bildung feinverteilter Ausscheidungen (Karbide, Nitride, Karbonitride) abgekühlt. Das Verfahren ermöglicht in einfacher und kostengünstiger Weise ohne aufwendige Vergütung die Herstellung hochfester Profile, insbesondere Rohrprofile, die maschinell schweißar sind.Process for producing profiles with a yield strength of> = 500 N / mm², a tensile strength of> = 600 N / mm² and high toughness from hot-rolled steel strip or sheet with the following process steps; a) the steel strip or sheet consisting of a precipitation-hardenable fine-grained steel is aged from the rolling heat after the last rolling pass from a final rolling temperature above the A1 temperature to a temperature of about 400 ° C. and then cooled to room temperature; b) the steel strip or sheet is cold worked into an open profile; c) the profile is subjected to solution annealing to dissolve the coarse precipitates and then cooled to form finely divided precipitates (carbides, nitrides, carbonitrides). The method enables the production of high-strength profiles, in particular tubular profiles, which can be welded by machine, in a simple and cost-effective manner without complex remuneration.

Description

Die Erfindung betrifft ein Verfahren gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a method according to the preamble of claim 1.

Angestrebt wird der Einsatz von Profilen mit hohen Festigkeitskennwerten im Lieferzustand zur Verwendung als Konstruktionsteile dann, wenn hohe Bauteilfestigkeiten bei kleinen Gewichten erzielt werden sollen, z.B. für Fahrzeugteile, Hydraulikzylinder, Stahlhochbauteile oder, wenn bei der konstruktiven Begrenzung der Abmessungen hohe Belastungen zwangsläufig sind, wie z.B. bei Ölfeldrohren für die Bohrtechnik.The aim is the use of profiles with high strength characteristics as supplied for use as structural parts when high B auteilfestigkeiten are to be achieved at low weights, for example for vehicle parts, hydraulic cylinder, steel high parts or when high loads are inevitably in the structural limitation of the dimensions as eg for oil field pipes for drilling technology.

In bekannter Weise werden bei der Warmherstellung von z.B. nahtlosen Rohren naturharte Stähle mit höheren Kohlenstoffgehalten bis zu o,5o% C und/oder anderen festigkeitssteigernden Legierungszusätzen eingesetzt. Bei der Herstellung von aus Bändern oder Blechen geformten und ggfs. zum Rohrprofil verschweißten Profilen stößt der Einsatz derartiger Stähle bei der Kaltverarbeitung, Zerteilen, Besäumen, Einformen zum Profil wegen des hohen Formänderungswiderstandes und bei der maschinellen Schweißung, insbesondere wegen mangelnder Hochfrequenz-Schweißbarkeit auf bisher nicht zu überwindende Schwierigkeiten.In a known manner, naturally hard steels with higher carbon contents up to 0.50% C and / or other strength-increasing alloy additives are used in the hot production of, for example, seamless tubes. In the manufacture of profiles formed from strips or sheets and, if necessary, welded to the tubular profile, the use of such steels in cold processing, cutting, trimming, shaping to form the profile has hitherto been encountered because of the high resistance to deformation and with mechanical welding, in particular because of a lack of high-frequency weldability difficulties that cannot be overcome.

Die Beeinträchtigung der maschinellen Hochfrequenz-Schweißbarkeit könnte zwar sowohl durch den Einsatz der nach dem Warmwalzen flüssigkeitsvergüteten Stähle (z.B. STE 70, Merkblatt 365, "Feinkornbaustähle für geschweißte Konstruktionen" Teil C, Beratungsstelle für Stahlverwendung, Düsseldorf, 1. Auflage 1972) als auch durch den Einsatz von gegenüber den normalgeglühten Feinkornbaustählen (Merkblatt 365, Teil B) mit erhöhten Streckgrenzen hergestellten Feinkornstählen vermieden werden. Es besteht jedoch auch hier das Problem, daß der Werkstoff zwar die für den Lieferzustand geforderte hohe Festigkeit hat, aber aufgrund des hohen Formänderungswiderstandes für die Kaltverarbeitung zu Profilen nicht geeignet ist. In der Praxis haben diese Gegebenheiten bei der Herstellung von z.B. geschweißten Rohren zu einer Begrenzung der Streckgrenze der Profile auf etwa 5oo N/mm2 und der Zugfestigkeit auf etwa 65o N/mm2 geführt. Die Rohre müssen demgemäß aus Bändern oder Blechen weicher Güten mit einer Streckgrenze bis 5oo N/mm2 geformt, geschweißt und bei höheren Anforderungen an die Streckgrenze flüssigkeitsgehärtet und angelassen, d.h. vergütet werden.The impairment of mechanical high-frequency weldability could indeed be caused by the use of steels that have been liquid-tempered after hot rolling (e.g. STE 7 0 , leaflet 365, "Fine-grained structural steels for welded constructions" part C, advice center for steel use, Düsseldorf, 1st edition 1972) as well can be avoided by using fine-grain steels produced with higher yield strengths than normal-annealed fine-grain structural steels (leaflet 365, part B). However, there is also the problem here that the material has the high strength required for the delivery state, but is not suitable for cold processing into profiles due to the high resistance to deformation. In practice, these conditions have limited the yield strength of the profiles to about 5oo N / mm2 and the tensile strength to about 65o N / mm2 when manufacturing, for example, welded pipes. Accordingly, the pipes must be formed from strips or sheets of soft grades with a yield strength of up to 5oo N / mm2, welded and, if the demands on the yield strength are higher, liquid-hardened and tempered, ie tempered.

Die Erhöhung von Zugfestigkeit und Streckgrenze durch eine Flüssigkeitshärtung und ein Anlassen (Vergüten) ist jedoch kostenaufwendig und nachteilig, weil die zuvor erzeugten höheren Festigkeitswerte wieder verloren gehen, wenn nachfolgend eine austenitisierende Wärmebehandlung, beispielsweise ein Normalisieren, Warmumformen etc. vorgenommen werden muß.However, the increase in tensile strength and yield strength through liquid hardening and tempering (tempering) is costly and disadvantageous because the higher strength values previously generated are lost again when an austenitizing heat treatment, for example normalizing, hot forming, etc. has to be carried out subsequently.

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren der eingangs genannten Art anzugeben, mittels dessen die Nachteile der bekannten Verfahren vermieden und auf verhältnismäßig einfache und daher auch kostengünstige Weise unter Vermeidung einer aufwendigen Vergütung eine Herstellung hochfester Profile, insbesondere geschlossener Rohrprofile mit einer Streckgrenze von mehr als 50o N/mm2, einer Zugfestigkeit von mehr als 600 N/mm und hoher Zähigkeit einschließlich des erforderlichen maschinellen Schweißens ermöglicht wird.The invention has for its object to provide a method of the type mentioned, by means of which the disadvantages of the known methods avoided and in a relatively simple and therefore cost-effective manner while avoiding expensive remuneration a manufacture of high-strength profiles, in particular closed tube profiles with a yield strength of more than 5 0 o N / mm2, a tensile strength of more than 6 00 N / mm and high toughness, including the required mechanical welding.

Diese Aufgabe wird nach der Erfindung durch die Kombination der folgenden Verfahrensschritte gelöst:

  • a) das aus einem ausscheidungshärtbaren Feinkornstahl bestehende Stahlband oder -blech wird aus der Walzhitze nach dem letzten Walzstich von einer Endwalztemperatur oberhalb der A1-Temperatur auf eine Temperatur von etwa 400° C überalternd warmausgelagert und anschließend auf Raumtemperatur abgekühlt;
  • b) das Stahlband oder -blech wird zu einem offenen Profil kaltverarbeitet;
  • c) das Profil wird einer Lösungsglühung zur Auflösung der groben Ausscheidungen unterworfen und anschließend zur Bildung feinverteilter Ausscheidungen (Karbide, Nitride, Karbonitride) abgekühlt.
This object is achieved according to the invention by combining the following process steps:
  • a) the steel strip or sheet consisting of a precipitation-hardenable fine-grained steel is aging-aged from the rolling heat after the last rolling pass from a final rolling temperature above the A 1 temperature to a temperature of about 400 ° C. and then cooled to room temperature;
  • b) the steel strip or sheet is cold worked into an open profile;
  • c) the profile is subjected to solution annealing to dissolve the coarse precipitates and then cooled to form finely divided precipitates (carbides, nitrides, carbonitrides).

Unter einem ausscheidungshärtbaren Feinkornstahl wird dabei bevorzugter Weise ein Stahl verstanden, der eine Zusammensetzung von

Figure imgb0001
Rest Eisen und übliche Verunreinigungen hat und-der im fertigen Zustand eine ASTM-Korngröße von feiner 6 aufweist. Mit Vorteil wird bei dem erfindungsgemäßen Verfahren die überalternde Warmauslagerung des ausscheidungshärtbaren Feinkornstahles, bei der keine Kornverfeinerung erfolgt, während des Abkühlens des oberhalb der A1-Temperatur, vorzugsweise bei 85o bis 750° C zu einem Bund gehaspelten Stahlbandes durchgeführt.A precipitation-hardenable fine-grain steel is preferably understood to mean a steel which has a composition of
Figure imgb0001
 Remainder has iron and usual impurities and - which in the finished state has an ASTM grain size of finer 6. Advantageously, in the inventive method, the überalternde artificial aging of the precipitation hardenable fine-grain steel, is done in which no grain refinement during cooling, preferably made of the above the A 1 temperature at 85o to 75 0 ° C to a collar gehaspelten steel strip.

Durch diese verhältnismäßig hohen Haspeltemperaturen mit nachfolgender Abkühlung allein durch die natürliche Wärmeabstrahlung des Bundes wird eine verlangsamte Abkühlungsgeschwindigkeit erreicht, durch die feinverteilte Ausscheidungen vermieden und koagulierte Ausscheidungen erreicht werden. Eine entsprechende Gefügeausbildung wird nach der Erfindung bei Blechen durch eine Ofenabkühlung, durch die Abstrahlung und Konvektion verhindert werden, aus der Walzhitze erreicht. Sowohl beim gehappelten Stahlband als auch beim Stahlblech ist es wesentlich, daß die verlangsamte Abkühlung bis zu einer Temperatur von 400°C geführt wird, während die nachfolgende Abkühlung auf Raumtemperatur in beliebiger Weise durchgeführt wird.Due to these relatively high reel temperatures with subsequent cooling solely by the natural heat radiation of the federal government, a slower cooling rate is achieved, through which finely divided excretions are avoided and coagulated excretions are achieved. A corresponding microstructure is achieved according to the invention in sheet metal by furnace cooling, by means of which radiation and convection are prevented, from the rolling heat. Both with the rolled steel strip As with steel sheet, it is essential that the slowed down cooling is carried out up to a temperature of 400 ° C., while the subsequent cooling down to room temperature is carried out in any way.

Aufgrund des durch die Warmauslagerung erzielten niedrigen Formänderungswiderstandes des Stahlbandes bzw. -bleches kann dieses ohne Schwierigkeiten zu einem zunächst offenen Profil kaltverarbeitet, d.h. zerteilt, besäumt, eingeformt, kalibriert und gerichtet werden. Ein auf diese Weise kalt hergestelltes offenes Profil wird nach der Erfindung bevorzugter Weise vor der weiteren Behandlung zu einem geschlossenen Rohrprofil verschweißt.Due to the low deformation resistance of the steel strip or sheet, which is achieved by hot aging, it can easily be cold-worked into an initially open profile, i.e. cut, trimmed, molded, calibrated and straightened. An open profile produced cold in this way is preferably welded to a closed tubular profile before further treatment according to the invention.

Die nach der Erfindung hergestellten offenen bzw. geschlossenen Profile werden nachfolgend, um eine Ausscheidungshärtung, die auch als Teilchenhärtung und Feinkornhärtung bezeichnet wird, herbeizuführen, zur Auflösung der groben Ausscheidungen einer Lösungsglühung oberhalb der AC3- Temperatur mit nachfolgender Abkühlung unterworfen. In jedem Fall soll durch die Art der Abkühlung die Bildung feinverteilter Karbide, Nitride und Karbonitride bei gleichzeitiger Feinkornbildung erreicht werden. Wird die Erfindung im Rahmen der Herstellung streckreduzierter Rohre angewendet, sowwird in vorteilhafter Weise die Temperatur der Lösungsglühung gleich der Temperatur gewählt, mit der das Streckreduzieren des Ausgangsrohres begonnen wird, d.h. der Anstichtemperatur. Eine gesonderte Lösungsglühung ist dann bei diesen streckreduzierten Rohren nicht mehr erforderlich, da die dem Lösungsglühen folgende Abkühlung während des Streckreduzierens bzw. im unmittelbaren Anschluß daran erfolgt.The open or closed profiles produced according to the invention are subsequently subjected to a solution annealing above the A C3 temperature with subsequent cooling in order to bring about precipitation hardening, which is also referred to as particle hardening and fine grain hardening. In any case, the type of cooling should be used to achieve the formation of finely divided carbides, nitrides and carbonitrides with simultaneous fine grain formation. If the invention is used in the production of reduced-stretch pipes, the temperature of the solution heat treatment is advantageously selected to be the temperature at which the stretch reduction of the starting pipe is started, ie the piercing temperature. A separate solution annealing is then no longer required in these reduced-stretch pipes, since the cooling following the solution annealing takes place during the reduction in stretch or immediately afterwards.

Eine gegebenenfalls erforderliche Nachausscheidung von Nitriden, Karbiden bzw. Karbonitriden und dementsprechend eine Verbesserung der angestrebten Eigenschaften der Fertigprodukte wird durch ein Anlassen bei einer Temperatur von 5oo bis 600° C erzielt. Mit Vorteil kann dieses Anlassen auch in der Weise durchgeführt werden, daß die dem Lösungsglühen folgende Abkühlung unterbrochen und im Bereich von 5oo bis 600° C mit verminderter Abkühlungsgeschwindigkeit fortgeführt wird.If needed, Nachausscheidung of nitrides, carbides or carbonitrides and, accordingly, an improvement in the desired properties of the finished products is achieved by tempering at a temperature of 00 ° C 5oo to 6. This tempering can advantageously also be carried out in such a way that the cooling following the solution annealing is interrupted and continued in the range from 5oo to 600 ° C. with a reduced cooling rate.

Die Vorteile des Verfahrens nach der Erfindung sind im wesentlichen zunächst darin zu sehen, daß auf kostengünstige Weise und zwar unter Vermeidung einer aufwendigen Flüssigkeitsvergütung hochfeste Profile, insbesondere geschlossene Rohrprofile, einschließlich des erforderlichen maschinellen Schweißens herstellbar sind. Insbesondere wird durch dieses Verfahren und den zum Einsatz gelangenden ausscheidungshärtbaren Feinkornstahl die mangelnde maschinelle Schweißbarkeit bisher eingesetzter Stähle beseitigt und gleichzeitig eine ausreichende Kaltverarbeitungsfähigkeit während des Herstellungsverfahrens erreicht.The advantages of the method according to the invention are essentially to be seen firstly in the fact that high-strength profiles, in particular closed tube profiles, including the required mechanical welding, can be produced in a cost-effective manner, while avoiding expensive liquid remuneration. In particular, this process and the precipitation-hardenable fine-grained steel used eliminate the lack of mechanical weldability of previously used steels and at the same time achieve sufficient cold workability during the production process.

Im folgenden ist das Verfahren nach der Erfindung anhand eines bevorzugten Ausführungsbeispieles näher erläutert.The method according to the invention is explained in more detail below on the basis of a preferred exemplary embodiment.

Ein Stahl mit einer chemischen Zusammensetzung von

Figure imgb0002
Figure imgb0003
 A steel with a chemical composition of
Figure imgb0002
Figure imgb0003

Rest Eisen und unvermeidliche Verunreinigungen wird nach dem Warmwalzen zum Band, vorzugsweise Warmbreitband ohne Zwischenkühlung nach dem letzten Walzstich bei einer Temperatur von etwa 750° C zu einem Bund (Coil) gehaspelt und an ruhender Luft bis 400°C abgekühlt.Balance iron and unavoidable impurities after hot rolling the band, preferably W armbreitband without intermediate cooling after the last W alzstich at a temperature of about 750 ° C into a coil (coil) is coiled and cooled in still air to 400 ° C.

Bei dieser Abkühlung des Bundes von der Haspeltemperatur auf 400° C wird die natürliche Wärmespeicherfähigkeit des Bundes für das überalternde Warmauslagern genutzt, bei dem die Ausscheidung und Koagulation der Karbide, Nitride und Karbonitride unter Vermeidung einer Kornverfeinerung weitgehend vollständig ablaufen. Die weitere Abkühlung auf Raumtemperatur erfolgt auf beliebige Weise. Das Warmbreitband weist nach der vollständigen Abkühlung auf Raumtemperatur bzw. dem Uberaltern eine Streckgrenze von 455 N/mm2 und eine Zugfestigkeit von 65o N/mm2 auf .In this cooling of the Federal of the coiling temperature to 400 ° C, the natural heat storage capacity of the Federal is used for the armauslagern überalternde W, in which the precipitation and coagulation of the carbides, nitrides and carbonitrides largely proceed to completion while avoiding a grain refinement. Further cooling to room temperature is done in any way. The hot broadband has a yield strength of 455 N / mm 2 and a tensile strength of 65o N / mm 2 after it has completely cooled to room temperature or has aged.

Das Warmbreitband wird darauf in Streifenzerteilt, soweit erforderlich besäumt und nachfolgend kalt umgeformt, im vorliegenden Beispiel im Durchlaufverfahren zu einem Schlitzrohr eingeformt, das mittels einer Hochfrequenz-Schweißeinrichtung zu einem Rohr mit einem Durchmesser von 159 mm verschweißt wird.The hot wide strip is then cut into strips, if necessary trimmed and subsequently cold-formed, in the present example in a continuous process formed into a slotted tube, which is welded to a tube with a diameter of 159 mm by means of a high-frequency welding device.

Dieses Rohr wird auf eine Temperatur von etwa 1030° C erwärmt und mit dieser Temperatur.als Anstichtemperatur in einem Streckreduzierverfahren auf den gewünschten Durchmesser von 60,3 mm gewalzt. Das fertige Rohr wird auf einem Kühlbett an ruhender Luft auf Raumtemperatur abgekühlt.This tube is heated to a temperature of about 1 0 3 0 ° C and with this temperature as the piercing temperature in a stretch reduction process to the ge desired diameter of 6 0 , 3 mm rolled. The finished tube is cooled on a cooling bed in still air to room temperature.

Während des Aufheizens bzw. Haltens des Rohres auf Walztemperatur werden die groben Karbide, Nitride und Karbonitride im Stahl gelöst und während der Abkühlung bzw. nach dem Walzen fein verteilt bei gleichzeitiger Feinkornbildung ausgeschieden.The coarse carbides, nitrides and carbonitrides are dissolved in the steel while the tube is being heated or held to the rolling temperature and are finely distributed during cooling or after the rolling with simultaneous formation of fine grains.

Das fertige Rohr weist nach dieser Behandlung eine Streckgrenze von 648 N/mm2 und eine Zug- festigkeit von 845 N/mm2 auf.The finished tube has after this treatment, a yield strength of 648 N / mm 2 and a Z ug strength of 845 N / mm to 2.

Claims (9)

1. Verfahren zum Herstellen von Profilen mit einer Streckgrenze von ≥ 500 N/mm2, einer Zugfestigkeit von ≥ 600 N/mm2 und hoher Zähigkeit aus warmgewalztem Stahlband oder -blech, gekennzeichnet durch die Kombination der folgenden Verfahrensschritte: a) das aus einem ausscheidungshärtbaren Feinkornstahl bestehende Stahlband oder -blech wird aus der Walzhitze nach dem letzten Walzstich von einer Endwalztemperatur oberhalb der A1-Temperatur auf eine Temperatur von etwa 400°C überalternd warmausgelagert und anschließend auf Raumtemperatur abgekühlt; b) das Stahlband oder blech wird zu einem offenen Profil kaltverarbeitet; c) das Profil wird einer Lösungsglühung zur Auflösung der groben Ausscheidungen unterworfen und anschließend zur Bildung feinverteilter Ausscheidungen (Karbide, Nitride, Karbonitride) abgekühlt. 1. A process for producing profiles with a yield strength of ≥ 500 N / mm 2 , a tensile strength of ≥ 600 N / mm 2 and high toughness from hot-rolled steel strip or sheet, characterized by the combination of the following process steps: a) the steel strip or sheet consisting of a precipitation-hardenable fine-grained steel is aging-aged from the rolling heat after the last rolling pass from a final rolling temperature above the A 1 temperature to a temperature of about 400 ° C. and then cooled to room temperature; b) the steel strip or sheet is cold worked into an open profile; c) the profile is subjected to solution annealing to dissolve the coarse precipitates and then cooled to form finely divided precipitates (carbides, nitrides, carbonitrides). 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das zu einem Bund gehaspelte Stahlband während des Abkühlens überalternd warmausgelagert wird.2. The method according to claim 1, characterized in that the steel strip reeled into a bundle is aged over aging while cooling. 3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Stahlblech durch eine Ofenabkühlung aus der Walzhitze überalternd warmausgelagert wird.3. The method according to claim 1, characterized in that the steel sheet is aged over aging by furnace cooling from the rolling heat. 4. Verfahren nach einem oder mehreren der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß das offene Profil zu einem geschlossenen Rohrprofil verschweißt wird.4. The method according to one or more of claims 1 to 3, characterized in that the open profile is welded to a closed tubular profile. 5. Verfahren nach einem oder mehreren der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß das Profil oberhalb der AC3-Temperatur lösungsgeglüht wird.5. The method according to one or more of claims 1 to 4, characterized in that the profile is solution-annealed above the A C3 temperature. 6. Verfahren nach einem oder mehreren der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß das geschlossene Rohrprofil mit einer der Lösungsglühtemperatur entsprechenden Anstichtemperatur streckreduziert wird.6. The method according to one or more of claims 1 to 5, characterized in that the closed tube profile is reduced in stretch with a solution temperature corresponding to the solution annealing temperature. 7. Verfahren nach den Ansprüchen 1 bis 6, dadurch gekennzeichnet, daß die Profile bei einer Temperatur von 5oo bis 600° C angelassen werden.7. The method according to claims 1 to 6, characterized in that the profiles are tempered at a temperature of 5oo to 6 00 ° C. 8. Verfahren nach den Ansprüchen 1 bis 7, dadurch gekennzeichnet, daß die dem Lösungsglühen folgende Abkühlung unterbrochen und im Bereich von 5oo bis 600°C mit verminderter Abkühlungsgeschwindigkeit fortgeführt wird.8. The method according to claims 1 to 7, characterized in that the cooling following the solution annealing is interrupted and continued in the range of 5oo to 600 ° C with a reduced cooling rate. 9. Die Verwendung eines ausscheidungshärtbaren Feinkornstahles als Werkstoff zur Herstellung von maschinell geschweißten, insbesondere hochfrequenzgeschweißten hochfesten Profilen, insbesondere Rohren, die ohne Vergütung eine Streckgrenze von ≥ 5oo N/mm2, einer Zugfestigkeit von ≥ 600 N/mm2 und hoher Kerbschlagzähigkeit aufweisen.9. The use of a precipitation-F einkornstahles as a material for producing welded by machine, especially high-frequency welded high-strength profiles, particularly tubes, which without compensation has a yield point of ≥ 5oo N / mm 2, a tensile strength of ≥ 6 00 N / mm 2 and high impact strength exhibit.
EP79104823A 1979-01-02 1979-12-01 Method for making profiles and the use of a fine grained steel for profiles Expired EP0013331B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2900022A DE2900022C3 (en) 1979-01-02 1979-01-02 Process for producing profiles
DE2900022 1979-01-02

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EP0013331A1 true EP0013331A1 (en) 1980-07-23
EP0013331B1 EP0013331B1 (en) 1982-09-15

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US (2) US4414042A (en)
EP (1) EP0013331B1 (en)
JP (1) JPS5591941A (en)
CA (1) CA1125150A (en)
DE (1) DE2900022C3 (en)
ES (1) ES487392A1 (en)
GR (1) GR66519B (en)
MX (1) MX152698A (en)
NO (1) NO151295C (en)
RO (1) RO80871A (en)
SU (1) SU1087078A3 (en)

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EP1437422A4 (en) * 2001-06-14 2006-08-23 Jfe Steel Corp Steel pipe having high formability and method for production thereof
US20080026241A1 (en) * 2006-07-25 2008-01-31 Algoma Tubes, Inc. Steel tubing with enhanced slot-ability characteristics for warm temperature service in casing liner applications and method of manufacturing the same
HUP1300743A2 (en) * 2013-12-19 2015-06-29 Dunaujvarosi Foeiskola Technical layout and method for hot rolling of mp and trip steel based on controled heat dissipation
CN112410513A (en) * 2020-10-14 2021-02-26 无锡市翰沃机械有限公司 Manufacturing method of high-altitude vehicle connecting shaft

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Also Published As

Publication number Publication date
EP0013331B1 (en) 1982-09-15
SU1087078A3 (en) 1984-04-15
DE2900022A1 (en) 1980-07-03
US4732623A (en) 1988-03-22
GR66519B (en) 1981-03-24
NO151295C (en) 1985-03-13
NO794340L (en) 1980-07-03
JPS5591941A (en) 1980-07-11
MX152698A (en) 1985-10-15
DE2900022C3 (en) 1981-12-03
DE2900022B2 (en) 1981-02-26
US4414042A (en) 1983-11-08
NO151295B (en) 1984-12-03
CA1125150A (en) 1982-06-08
RO80871A (en) 1983-02-01
ES487392A1 (en) 1980-09-16

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