EP0775757A1 - Process and apparatus for hot dipping age resistant steel sheet - Google Patents

Process and apparatus for hot dipping age resistant steel sheet Download PDF

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Publication number
EP0775757A1
EP0775757A1 EP96116218A EP96116218A EP0775757A1 EP 0775757 A1 EP0775757 A1 EP 0775757A1 EP 96116218 A EP96116218 A EP 96116218A EP 96116218 A EP96116218 A EP 96116218A EP 0775757 A1 EP0775757 A1 EP 0775757A1
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EP
European Patent Office
Prior art keywords
strip
hot
temperature
degrees celsius
cold
Prior art date
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Granted
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EP96116218A
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German (de)
French (fr)
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EP0775757B1 (en
Inventor
Walter Dr. Zimnik
Klaus Dr. Freier
Heino Dr. Buddenberg
Otto Schanderl
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Salzgitter AG
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Preussag Stahl 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C21D9/48—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals deep-drawing sheets
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/003—Apparatus
    • C23C2/0038—Apparatus characterised by the pre-treatment chambers located immediately upstream of the bath or occurring locally before the dipping process
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
    • C23C2/0224—Two or more thermal pretreatments
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/024—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by cleaning or etching
    • 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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0426—Hot rolling

Definitions

  • the invention relates to a method and a system for hot dip coating of steel strip.
  • the invention also relates to a hot dip coating obtainable by the method, that is to say in particular galvanized steel strip.
  • This steel strip should be resistant to aging, have good cold formability or deep-drawing capability, and should therefore be particularly suitable for producing body panels.
  • the steel strip should also have a quasi-isotropic deformation behavior (small delta r value) and a high yield strength.
  • DE-OS 15 21 376 it is known to heat the strips to 450 to 500 degrees before introduction into the zinc bath after the strip has previously been annealed in a reducing atmosphere at a temperature of 720 to 950 degrees.
  • the annealing treatment at temperatures of more than 500 degrees Celsius before the strip is introduced into the zinc bath is also provided as a basic measure in the further known prior art.
  • the strip is annealed at temperatures between 650 and 750 degrees.
  • the strip is heated to 750 to 800 degrees Celsius under non-oxidizing conditions before it is introduced into the zinc bath.
  • the strip is heated to 650 to 950 degrees Celsius before it is immersed in the zinc bath after cooling.
  • hot-dip coated strips can only be produced in a continuous process.
  • the usual aging treatment in which the strip must be kept below 450 degrees Celsius for at least 60 seconds, must be carried out by cooling in three cooling phases, each with a defined cooling rate.
  • the aim of this is to reduce the yield strength of the steels treated according to the invention and to increase the elongation at break.
  • An improvement in the aging resistance is said to have been achieved on samples that were tested after a four-week aging period in order to take into account the usual storage times between production and processing.
  • This beneficial effect is brought about by a decrease in the harmful, dissolved carbon content achieved with the cooling according to the invention.
  • the recommended cooling with defined cooling rates is preceded by an annealing treatment of 750 to 800 degrees Celsius. It also shows that it is not an aging-resistant sheet with a high yield strength.
  • the object of the invention was therefore to provide a hot-dip coated steel strip which is resistant to aging.
  • Another task is the production of a hot-dip galvanized sheet or strip, which combines a high yield strength or high strength with good cold formability or deep-drawing ability and has a quasi-isotropic drawing behavior.
  • the cold strip is then essentially only heated to the molten bath temperature before it is immersed in the molten bath.
  • the temperature of the strip surface is increased to no more than 500 degrees Celsius when galvanized.
  • the tape dips into the weld pool immediately after this heating.
  • the advantage of this is that, for example, both for the soft unalloyed grades and for the higher-strength micro-alloyed grades, the coated thin sheet has the same chemical composition and the same technological properties regardless of the type of coating (e.g. electrolytic or hot-dip galvanizing).
  • the technological properties of the coated steel strip depend not only on the chemical composition of the steel, but also on the heat treatment that the coated steel sheet has undergone.
  • hot-dip galvanized steel strip according to the invention is resistant to aging without additional measures, such as defined cooling phases.
  • the coating treatment can no longer be matched to the continuous annealing. With galvanizing, this is therefore no longer dependent on the recrystallization treatment in the continuous annealing. Therefore the belt speed can no longer be matched to the steel grade. The performance of the galvanizing system is therefore only determined by the design of the galvanizing part.
  • the hot-dip coated steel strip according to the invention is first explained in more detail with regard to the production of cold strip using the following exemplary embodiments for producing a cold strip with extremely low anisotropy (delta r ⁇ 0.2).
  • cold rolling degrees of up to 15% or 20% and up to 85% are preferably set. At values between 0.01% and 0.02%, lower degrees of cold rolling are preferred. A high level of tensile strength and yield strength could be assigned to the preferred cold rolling grades.
  • Table 2 shows the grain size achieved according to the invention in ASTM units; The achievable grain refinement compared to steels without titanium addition according to the prior art is considerable and extends up to ASTM 11. In contrast the comparative melts had a larger grain and increased anisotropy.
  • variable coiling temperature Th For a steel C (variants C3 to C5) tests were carried out with variable coiling temperature Th and annealing throughput Pg (Table 3). While fluctuations in the throughput of the bell annealer from 1.1 to 1.9 t / h did not adversely affect the grain size or the level anisotropy Delta r, an increase in the reel temperatures to 710 degrees Celsius with roughly the same roll temperatures resulted in a coarsening and an increase the plane anisotropy. The reel temperatures should therefore be between 520 and 710, preferably between 450 and 680 degrees Celsius. Table 1 Melt analysis (values in percent by weight) stole C.
  • the cold strip produced in this way is heated to essentially only the melt bath temperature after chemical cleaning in an oven under protective gas, preferably an induction oven.
  • Other coating methods, such as flame spraying, can also be used. According to the invention, it is important to heat the strip only to the extent necessary for the coating. With heating on Melt bath temperature "is therefore to be understood as heating to the temperature necessary for the coating.
  • the surface temperature of the strip with this heating is not more than 420 to 500 degrees Celsius.
  • the strip heated in this way is introduced directly, ie essentially without cooling, into the bath for the hot-dip coating.
  • the hot-dip coated tape After it has been cooled to about room temperature, the hot-dip coated tape is treated, stretch-oriented and chemically passivated or chemically pretreated and dried for a subsequent coating.
  • the coating can in particular consist of a multi-layer structure, for example of sealing, pre-priming and a multi-layer pre-coating. It is of crucial importance that the hot-dip coated steel strip according to the invention has no aging due to the heating to only the melt bath temperature of the cold strip used, even after painting.
  • the coating system according to the invention has a heating furnace 14 arranged directly in front of the hot-dip bath 4. In the oven, the ribbon is heated to substantially melt bath temperature. In a galvanizing plant, the surface temperature of the strip in the furnace is a maximum of 500 degrees Celsius. A temperature of 420 to 500 degrees Celsius is preferably set. As a result, the previously customary cooling and the previously customary aging are eliminated. An embodiment of the coating system is explained with reference to the embodiment shown schematically in the attached figure.
  • the strip reaches the heating furnace 14 via a strip store 2 (looper) via degreasing and drying 3.
  • the heating furnace 14 is preferably an induction furnace which is arranged immediately before the strip is introduced into the melting bath 4.
  • the band is heated from about room temperature (a), for example at a heating rate of 150 to 300 degrees Celsius / second under protective gas, to the desired temperature (b) and then leaves the molten bath 4 at approximately the molten bath temperature (c).
  • the strip cools down to predetermined temperatures (d, e), then passes into a skin pass mill 5, a stretching straightener 6 and a chemical treatment 7 with a dryer 8 10, 12 take place.
  • the finished coated tape is wound on a reel 13.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Coating With Molten Metal (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

Producing cold-rolled steel strip comprises heating the steel strip before an immersion-coating in a protective gas, to a temperature below the recrystallisation temperature to not more than 420-500 degrees C, in which the steel strip comprises (%): 0.02-0.06 C, 0.01-0.40 Si, 0.10-0.80 Mn, 0.005-0.08 P, 0.0005-0.02 S, 0.002-0.009 N, 0.015-0.08 Al, 0.01-0.04 Ti, maximum 0.15 Cu, V or Ni. Also claimed is an apparatus for carrying cut melt immersion coating comprising a furnace (14) arranged before the melt immersion bath (4), in which the temperature of the steel strip is adjusted to a value below the recrystallisation temperature to the temperature of the bath. Further claimed is the steel strip produced, consisting of the above components.

Description

Die Erfindung betrifft ein Verfahren und eine Anlage zur Schmelztauchbeschichtung von Stahlband. Die Erfindung betrifft außerdem ein mit dem Verfahren erhältliches, schmelztauchbeschichtes, also insbesondere verzinktes Stahlband. Dieses Stahlband soll alterungsbeständig sein, eine gute Kaltumformbarkeit beziehungsweise Tiefziehfähigkeit aufweisen, also insbesondere geeignet sein, um damit Karosseriebleche herzustellen. Das Stahlband soll außerdem ein quasi isotropes Verformungsverhalten (kleiner Delta r Wert) und eine hohe Streckgrenze aufweisen.The invention relates to a method and a system for hot dip coating of steel strip. The invention also relates to a hot dip coating obtainable by the method, that is to say in particular galvanized steel strip. This steel strip should be resistant to aging, have good cold formability or deep-drawing capability, and should therefore be particularly suitable for producing body panels. The steel strip should also have a quasi-isotropic deformation behavior (small delta r value) and a high yield strength.

Nach DE-OS 15 21 376 ist bekannt, die Bänder vor der Einführung in das Zinkbad auf 450 bis 500 Grad zu erwärmen, nachdem vorher in reduzierender Atmosphäre das Band bei einer Temperatur von 720 bis 950 Grad geglüht worden ist.According to DE-OS 15 21 376 it is known to heat the strips to 450 to 500 degrees before introduction into the zinc bath after the strip has previously been annealed in a reducing atmosphere at a temperature of 720 to 950 degrees.

Es war nach der gleichen Schritt ferner bekannt, weichgeglühte Bänder einzusetzen, bei denen keine Glühbehandlung erfolgt. Stattdessen werden die Bänder auf bis zu 230 Grad Celsius erwärmt und mit dieser Oberflächentemperatur durch das auf 450 Grad Celsius erhitzte Zinkbad gezogen. Dieses Verfahren hat jedoch den Nachteil, daß das Zinkbad durch eine unwirtschaftliche Induktionsheizung von außen beheizt werden muß und hierbei Schwierigkeiten auftreten. Es wurde deshalb vorgeschlagen, die Bänder weiterhin weichzuglühen, zu reinigen und in reduzierender Atmosphäre auf eine Temperatur zwischen 500 und 720 Grad Celsius zu erwärmen, bevor das Band mit etwa 480 Grad Celsius in das Zinkbad eingeführt wird. Hierdurch sollte eine Streckgrenze von nur 20 kg/mm2 erreicht werden.After the same step, it was also known to use soft-annealed strips in which no annealing treatment takes place. Instead, the strips are heated up to 230 degrees Celsius and pulled at this surface temperature through the zinc bath heated to 450 degrees Celsius. However, this method has the disadvantage that the zinc bath has to be heated from the outside by an uneconomical induction heating system and difficulties arise. It has therefore been proposed to continue soft annealing, cleaning and heating the strips to a temperature between 500 and 720 degrees Celsius in a reducing atmosphere before the strip is introduced into the zinc bath at around 480 degrees Celsius. This should achieve a yield strength of only 20 kg / mm 2 .

Die Glühbehandlung bei Temperaturen von mehr als 500 Grad Celsius vor der Einführung des Bandes in das Zinkbad ist auch im weiter bekannten Stand der Technik als grundsätzliche Maßnahme vorgesehen.The annealing treatment at temperatures of more than 500 degrees Celsius before the strip is introduced into the zinc bath is also provided as a basic measure in the further known prior art.

So wird zum Beispiel in DE-OS 16 21 340 das Band bei Temperaturen zwischen 650 und 750 Grad geglüht.For example, in DE-OS 16 21 340 the strip is annealed at temperatures between 650 and 750 degrees.

Nach DE-OS 23 40 413 wird das Band unter nichtoxidierenden Bedingungen auf 750 bis 800 Grad Celsius erhitzt, bevor es in das Zinkbad eingeführt wird.According to DE-OS 23 40 413, the strip is heated to 750 to 800 degrees Celsius under non-oxidizing conditions before it is introduced into the zinc bath.

Nach DE 27 11 041 wird das Band auf 650 bis 950 Grad Celsius erwärmt, bevor es nach Abkühlung in das Zinkbad eintaucht.According to DE 27 11 041, the strip is heated to 650 to 950 degrees Celsius before it is immersed in the zinc bath after cooling.

Nach DE 40 38 186 C1 können im Schmelztauchverfahren oberflächenveredelte Bänder nur in einem Durchlaufverfahren hergestellt werden. Dabei muß nach einem Glühprozeß die sonst übliche Überalterungsbehandlung, bei der das Band für wenigstens 60 Sekunden unterhalb 450 Grad Celsius gehalten werden muß, durch eine Abkühlung in drei Kühlphasen mit jeweils definierter Abkühlgeschwindigkeit erfolgen. Hierdurch soll erreicht werden, daß die Streckgrenze der erfindungsgemäß behandelten Stähle verringert und die Bruchdehnung erhöht wird. Wie sich an Proben, die nach einer Auslagerung von vier Wochen geprüft wurden, um übliche Lagerzeiten zwischen der Fertigung und der Verarbeitung zu berücksichtigen ergab, soll eine Verbesserung der Alterungsbeständigkeit erreicht worden sein. Diese günstige Wirkung wird durch eine mit der erfindungsgemäßen Abkühlung erzielten Abnahme des schädlichen, gelösten Kohlenstoffgehaltes hervorgerufen. Auch in diesem Fall geht der empfohlenen Abkühlung mit definierten Abkühlungsgeschwindigkeiten eine Glühbehandlung von 750 bis 800 Grad Celsius voraus. Es zeigt sich außerdem, daß es sich nicht um ein alterungsbeständiges Blech mit hoher Streckgrenze handelt.According to DE 40 38 186 C1, hot-dip coated strips can only be produced in a continuous process. After an annealing process, the usual aging treatment, in which the strip must be kept below 450 degrees Celsius for at least 60 seconds, must be carried out by cooling in three cooling phases, each with a defined cooling rate. The aim of this is to reduce the yield strength of the steels treated according to the invention and to increase the elongation at break. An improvement in the aging resistance is said to have been achieved on samples that were tested after a four-week aging period in order to take into account the usual storage times between production and processing. This beneficial effect is brought about by a decrease in the harmful, dissolved carbon content achieved with the cooling according to the invention. In this case too, the recommended cooling with defined cooling rates is preceded by an annealing treatment of 750 to 800 degrees Celsius. It also shows that it is not an aging-resistant sheet with a high yield strength.

Aufgabe der Erfindung war es daher, ein schmelztauchbeschichtetes Stahlband bereitzustellen, das alterungsbeständig ist. Eine weitere Aufgabe ist die Herstellung eines feuerverzinkten Bleches oder Bandes, das eine hohe Streckgrenze beziehungsweise eine hohe Festigkeit mit einer guten Kaltumformbarkeit beziehungsweise Tiefziehfähigkeit vereint und ein quasi isotropes Ziehverhalten aufweist.The object of the invention was therefore to provide a hot-dip coated steel strip which is resistant to aging. Another task is the production of a hot-dip galvanized sheet or strip, which combines a high yield strength or high strength with good cold formability or deep-drawing ability and has a quasi-isotropic drawing behavior.

Ein diese Aufgabe lösendes, schmelztauchbeschichtetes Kaltband ist erhältlich, indem das Kaltband, welches z. B. folgende Analyse aufweist:

  • 0,02 bis 0,06 % Kohlenstoff, vorzugsweise 0,03 bis 0,48 % Kohlenstoff,
  • 0,01 bis 0,40 % Silizium, bevorzugt bis 0,06 % Silizium,
  • 0,10 bis 0,80 % Mangan,
  • 0,005 bis 0,08 % Phosphor,
  • 0,0005 bis 0,02 % Schwefel,
  • 0,002 bis 0,009 % Stickstoff,
  • 0,015 bis 0,08 % Aluminium,
  • 0,01 bis 0,04 % Titan,
  • max. 0,15 % von einem oder mehreren Elemente Kupfer, Vanadium, Nickel,
  • Rest Eisen und unvermeidbare Verunreinigungen,
rekristallisierend im Haubenofen geglüht wird.A hot-dip coated cold strip that solves this problem is available by the cold strip, which, for. B. has the following analysis:
  • 0.02 to 0.06% carbon, preferably 0.03 to 0.48% carbon,
  • 0.01 to 0.40% silicon, preferably up to 0.06% silicon,
  • 0.10 to 0.80% manganese,
  • 0.005 to 0.08% phosphorus,
  • 0.0005 to 0.02% sulfur,
  • 0.002 to 0.009% nitrogen,
  • 0.015 to 0.08% aluminum,
  • 0.01 to 0.04% titanium,
  • Max. 0.15% of one or more elements copper, vanadium, nickel,
  • Rest of iron and unavoidable impurities,
is recrystallizing annealed in the hood furnace.

Das Kaltband wird dann vor dem Eintauchen in das Schmelzbad im wesentlichen nur noch auf Schmelzbadtemperatur erwärmt. Dabei wird insbesondere die Tempertur der Bandoberfläche bei einer Verzinkung auf nicht mehr als 500 Grad Celsius erhöht. Das Band taucht unmittelbar nach dieser Erwärmung in das Schmelzbad ein. Der Vorteil hierbei ist, daß zum Beispiel sowohl bei den weichen unlegierten Güten als auch bei den höherfesten mikrolegierten Güten das beschichtete Feinblech unabhängig von der Beschichtungsart (zum Beispiel elektrolytische Verzinkung oder Feuerverzinkung) die gleiche chemische Zusammensetzung und die gleichen technologischen Eigenschaften aufweisen. Die technologischen Eigenschaften des beschichteten Stahlbandes sind nicht nur von der chemischen Zusammensetzung des Stahles abhängig, sondern auch von der Wärmebehandlung, die das beschichtete Stahlblech durchlaufen hat. Für die Bandverzinkung hat die Technik sich grundsätzlich in die Richtung bewegt, mit der Bandverzinkung eine Durchlaufglühe zu kombinieren. Dabei wird das Band auf die oben beschriebenen hohen Temperaturen aufgeheizt. Um mit diesem Verfahren die gleichen technologischen Eigenschaften zu erzeugen, wie sie zum Beispiel bei haubengeglühtem Material (zum Beispiel ST14) in Verbindung mit einer elektrolytischen Beschichtung erreicht werden, muß für die Feuerverzinkung ein höherwertiges Material (zum Beispiel IF-Stahl) eingesetzt werden. Die jetzt vorgeschlagene, von der bisher üblichen Durchlaufglühe in Verbindung mit einer Schmelztauchbeschichtung abweichende Verfahrensführung führt zu dem wesentlichen Vorteil, daß die Verarbeitung des beschichteten Bleches nicht mehr an die Beschichtungsart angepaßt werden muß. So sind die gleichen technologischen Eigenschaften bei gleicher chemischer Analyse, unabhängig von der Beschichtungsart erreichbar.The cold strip is then essentially only heated to the molten bath temperature before it is immersed in the molten bath. In particular, the temperature of the strip surface is increased to no more than 500 degrees Celsius when galvanized. The tape dips into the weld pool immediately after this heating. The advantage of this is that, for example, both for the soft unalloyed grades and for the higher-strength micro-alloyed grades, the coated thin sheet has the same chemical composition and the same technological properties regardless of the type of coating (e.g. electrolytic or hot-dip galvanizing). The technological properties of the coated steel strip depend not only on the chemical composition of the steel, but also on the heat treatment that the coated steel sheet has undergone. For strip galvanizing, technology has basically moved in the direction of combining continuous annealing with strip galvanizing. The strip is heated to the high temperatures described above. In order to produce the same technological properties with this process as can be achieved, for example, with annealed material (e.g. ST14) in connection with an electrolytic coating, a higher quality material (e.g. IF steel) must be used for hot-dip galvanizing. The The proposed procedure, which differs from the previously usual continuous annealing in connection with a hot-dip coating, leads to the essential advantage that the processing of the coated sheet no longer has to be adapted to the type of coating. This means that the same technological properties can be achieved with the same chemical analysis, regardless of the type of coating.

Darüber hinaus ist das erfindungsgemäße feuerverzinkte Stahlband ohne zusätzliche Maßnahmen - wie zum Beispiel definierte Abkühlphasen - alterungsbeständig.In addition, the hot-dip galvanized steel strip according to the invention is resistant to aging without additional measures, such as defined cooling phases.

Schließlich ist, da die bisher grundsätzlich verwendete Durchlaufglühe zur Rekristallisation nicht mehr notwendig ist, die Beschichtungsbehandlung nicht mehr auf die Durchlaufglühe abzustimmen. Bei einer Verzinkung ist diese also nicht mehr abhängig von der Rekristallisationsbehandlung in der Durchlaufglühe. Daher ist auch die Bandgeschwindigkeit nicht mehr auf die Stahlsorte abzustimmen. Die Leistung der Verzinkungsanlage ist demzufolge nur noch bestimmt durch die Auslegung des Verzinkungsteils.Finally, since the continuous annealing previously used for recrystallization is no longer necessary, the coating treatment can no longer be matched to the continuous annealing. With galvanizing, this is therefore no longer dependent on the recrystallization treatment in the continuous annealing. Therefore the belt speed can no longer be matched to the steel grade. The performance of the galvanizing system is therefore only determined by the design of the galvanizing part.

Das erfindungsgemäße schmelztauchbeschichtete Stahlband wird zunächst hinsichtlich der Kaltbandherstellung anhand der folgenden Ausführungsbeispiele zur Herstellung eines Kaltbandes mit äußerst geringer Anisotropie (Delta r < 0,2) näher erläutert.The hot-dip coated steel strip according to the invention is first explained in more detail with regard to the production of cold strip using the following exemplary embodiments for producing a cold strip with extremely low anisotropy (delta r <0.2).

Aus den Schmelzen A - D sowie dem Vergleichsschmelzen E - F (Tabelle 1) werden Brammen von 210 mm Dicke im Strang vergossen. Nach Erwärmung im Stoßofen auf 1250 Grad Celsius wurde die Bramme zu Warmband von 3 mm Dicke ausgewalzt, gehaspelt und auf Raumtemperatur abgekühlt. Die Walzendtemperaturen und Haspeltemperturen zeigt Tabelle 2. Nach dem Beizen wurden Bänder durch Kaltwalzen in unterschiedlichen Stufen von 10 % bis zu 80 % auf Feinblechdicke reduziert und erneut gehaspelt. Das Bund wurde im Haubenglühofen auf 700 Grad Celsius erwärmt, mit einem Durchsatz von 1,1 t/h bis 1,9 t/h rekristallisierend geglüht und anschließend im Ofen auf 120 Grad Celsius abgekühlt.From the melts A - D and the comparative melts E - F (Table 1) slabs 210 mm thick are cast in the strand. After heating in the pusher furnace to 1250 degrees Celsius, the slab was rolled out into 3 mm thick hot strip, coiled and cooled to room temperature. The final roll temperatures and reel temperatures are shown in Table 2. After pickling, strips were reduced by cold rolling in various stages from 10% to 80% to thin sheet thickness and reeled. The coil was heated in the bell annealing furnace to 700 degrees Celsius, annealed with a throughput of 1.1 t / h to 1.9 t / h and then cooled in the furnace to 120 degrees Celsius.

Die Kaltwalzung in Abhängigkeit vom Titangehalt erfolgt bei:

  • 0,01 % Titan mit 20-60 %, bevorzugt 30 - 50 % Kaltwalzgrad;
  • 0,02 % Titan mit 10-15 % oder 40 - 85 %, bevorzugt 50 - 80 % Kaltwalzgrad;
  • 0,03 % Titan mit 10 - 20 % oder 50 - 85%, bevorzugt 60 - 80 % Kaltwalzgrad;
  • 0,04 % Titan mit 15 - 25 % oder 55 - 80%, bevorzugt 20 % oder 60 - 70 % Kaltwalzgrad.
Cold rolling depending on the titanium content takes place at:
  • 0.01% titanium with 20-60%, preferably 30-50% cold rolling degree;
  • 0.02% titanium with 10-15% or 40-85%, preferably 50-80% cold rolling degree;
  • 0.03% titanium with 10-20% or 50-85%, preferably 60-80% degree of cold rolling;
  • 0.04% titanium with 15-25% or 55-80%, preferably 20% or 60-70% degree of cold rolling.

Für Zwischenwerte des Legierungselementes Titan, beispielsweise 0,025 % Ti, werden bevorzugt Kaltwalzgrade bis 15 % oder 20 % und bis 85 % eingestellt. Bei Werten zwischen 0,01 % und 0,02 % werden bevorzugt niedrigere Kaltwalzgrade eingestellt. Den bevorzugten Kaltwalzgraden konnte ein hohes Zugfestigkeits- und Streckgrenzenniveau zugeordnet werden.For intermediate values of the alloying element titanium, for example 0.025% Ti, cold rolling degrees of up to 15% or 20% and up to 85% are preferably set. At values between 0.01% and 0.02%, lower degrees of cold rolling are preferred. A high level of tensile strength and yield strength could be assigned to the preferred cold rolling grades.

Beispiel: Stahl BExample: Steel B

  • a) Kaltwalzgrad 10 bis 15 % =
    Streckgrenzenniveau Rp 0,2 = 400 bis 350 N/mm2
    Zugfestigkeitsniveau Rm = 450 bis 400 N/mm2     a) Cold rolling degree 10 to 15%
    Yield strength level R p 0.2 = 400 to 350 N / mm 2
    Tensile strength level R m = 450 to 400 N / mm 2
  • b) Kaltwalzgrad 30 % =
    Rp 0,2 = 180 N/mm2 und Rm = 320 N/mm2     b) Degree of cold rolling 30%
    R p 0.2 = 180 N / mm 2 and R m = 320 N / mm 2
  • c) Kaltwalzgrad 50 bis 80 % =
    Rp 0,2 = 250 bis 280 N/mm2 und Rm = 360 bis 370 N/mm2     c) Cold rolling degree 50 to 80%
    R p 0.2 = 250 to 280 N / mm 2 and R m = 360 to 370 N / mm 2

Diese Erkenntnis ermöglicht eine bauteil- oder funktionsangepaßte Wahl der Festigkeit für ein und dasselbe Bauteil durch Änderung der Parameter Titangehalt und Kaltwalzgrad.This knowledge enables component or function-specific selection of the strength for one and the same component by changing the parameters titanium content and degree of cold rolling.

Tabelle 2 zeigt die erfindungsgemäß erzielte Korngröße in ASTM-Einheiten; die erzielbare Kornverfeinerung gegenüber Stählen ohne Titanzusatz nach dem Stand der Technik ist erheblich und reicht bis ASTM 11. Demgegenüber wiesen die Vergleichsschmelzen ein größeres Korn und eine erhöhte Anisotropie auf.Table 2 shows the grain size achieved according to the invention in ASTM units; The achievable grain refinement compared to steels without titanium addition according to the prior art is considerable and extends up to ASTM 11. In contrast the comparative melts had a larger grain and increased anisotropy.

Für einen Stahl C (Varianten C3 bis C5) wurden Versuche mit variabler Haspeltemperatur Th und Glühdurchsatz Pg durchgeführt (Tabelle 3). Während Schwankungen in der Durchsatzmenge des Haubenglühofens von 1,1 bis 1,9 t/h sowohl die Korngröße als auch die ebene Anisotropie Delta r nicht negativ beeinflußten, hatte eine Erhöhung der Haspeltemperaturen auf 710 Grad Celsius bei annähernd gleichen Walzendtemperaturen eine Kornvergröberung und eine Erhöhung der ebenen Anisotropie zur Folge. Die Haspeltemperaturen sollten demzufolge zwischen 520 und 710, bevorzugt zwischen 450 und 680 Grad Celsius liegen. Tabelle 1 Schmelzanalyse (Werte in Gewichtsprozenten) Stahl C Si Mn P S Al N Ti Bemerkung A 0,046 0,02 0,17 0,009 0,011 0,022 0,0025 0,01 B 0,044 0,025 0,25 0,013 0,005 0,054 0,0032 0,02 C 0,048 0,03 0,24 0,014 0,006 0,051 0,0034 0,03 D 0,03 0,03 0,20 0,012 0,005 0,078 0,0050 0,04 E 0,04 0,02 0,25 0,020 0,015 0,061 0,0033 ---- Vergleich F 0,04 0,03 0,25 0,008 0,007 0,065 0,0047 ---- Vergleich Tabelle 2 Stahl Tw °C Th °C KASTM min/max A 860 490 10/7 B 870 500 11/9 C1 870 500 11/9 C2 880 450 11/9 D 890 430 11/9 E 900 710 9/4 F 890 500 9/6 Tabelle 3 Stahl Tw °C Th °C Pg t/h KASTM Δ r min/max C3 880 520 1,1 9 - 10 -0,07 / +0,06 C4 915 540 1,9 9 - 10 -0,04 / +0,08 C5 870 710 1,9 8 - 9 +0,09 / +0,17 For a steel C (variants C3 to C5) tests were carried out with variable coiling temperature Th and annealing throughput Pg (Table 3). While fluctuations in the throughput of the bell annealer from 1.1 to 1.9 t / h did not adversely affect the grain size or the level anisotropy Delta r, an increase in the reel temperatures to 710 degrees Celsius with roughly the same roll temperatures resulted in a coarsening and an increase the plane anisotropy. The reel temperatures should therefore be between 520 and 710, preferably between 450 and 680 degrees Celsius. Table 1 Melt analysis (values in percent by weight) stole C. Si Mn P S Al N Ti comment A 0.046 0.02 0.17 0.009 0.011 0.022 0.0025 0.01 B 0.044 0.025 0.25 0.013 0.005 0.054 0.0032 0.02 C. 0.048 0.03 0.24 0.014 0.006 0.051 0.0034 0.03 D 0.03 0.03 0.20 0.012 0.005 0.078 0.0050 0.04 E 0.04 0.02 0.25 0.020 0.015 0.061 0.0033 ---- comparison F 0.04 0.03 0.25 0.008 0.007 0.065 0.0047 ---- comparison stole Tw ° C Th ° C K ASTM min / max A 860 490 10/7 B 870 500 11/9 C1 870 500 11/9 C2 880 450 11/9 D 890 430 11/9 E 900 710 9/4 F 890 500 9/6 stole Tw ° C Th ° C Pg t / h K ASTM Δ r min / max C3 880 520 1.1 9-10 -0.07 / +0.06 C4 915 540 1.9 9-10 -0.04 / +0.08 C5 870 710 1.9 8 - 9 +0.09 / +0.17

In Tabelle 2 und 3 bedeuten:

Tw
Walzendtemperatur
Th
Haspeltemperatur
K
Korngröße nach ASTM
Pg
Glühdurchsatz
Δr
ebene Anisotropie
In tables 2 and 3:
Tw
End of roll temperature
Th
Reel temperature
K
Grain size according to ASTM
Pg
Annealing throughput
Δr
flat anisotropy

Das derart hergestellte Kaltband wird nach einer chemischen Reinigung in einem Ofen unter Schutzgas, bevorzugt einem Induktionsofen, auf im wesentlichen nur die Schmelzbadtemperatur erwärmt. Die Bezeichnung

Figure imgb0001
Schmelzbad" ist hier nur im Sinne eines Beispiels verwendet. Es können auch andere Beschichtungsverfahren, wie z. B. Flammsprühen, verwendet werden. Erfindungsgemäß kommt es darauf an, das Band nur soweit zu erwärmen, wie es für die Beschichtung notwendig ist. Unter Erwärmung auf
Figure imgb0002
Schmelzbadtemperatur" ist also eine Erwärmung auf die für die Beschichtung notwendige Temperatur zu verstehen.The cold strip produced in this way is heated to essentially only the melt bath temperature after chemical cleaning in an oven under protective gas, preferably an induction oven. The label
Figure imgb0001
Melting bath "is used here only for the purposes of one example. Other coating methods, such as flame spraying, can also be used. According to the invention, it is important to heat the strip only to the extent necessary for the coating. With heating on
Figure imgb0002
Melt bath temperature "is therefore to be understood as heating to the temperature necessary for the coating.

Bei einer Verzinkung beträgt die Oberflächentemperatur des Bandes bei dieser Erwärmung nicht mehr als 420 bis 500 Grad Celsius. Das derart erwärmte Band wird unmittelbar, also im wesentlichen ohne Abkühlung, in das Bad für die Schmelztauchbeschichtung eingeführt.With galvanizing, the surface temperature of the strip with this heating is not more than 420 to 500 degrees Celsius. The strip heated in this way is introduced directly, ie essentially without cooling, into the bath for the hot-dip coating.

Das schmelztauchbeschichtete Band wird nach einer Abkühlung auf etwa Raumtemperatur dressiert, streckgerichtet und chemisch passiviert beziehungsweise für eine nachfolgende Beschichtung chemisch vorbehandelt und getrocknet. Die Beschichtung kann insbesondere aus einem Mehrschichtaufbau, zum Beispiel aus Versiegelung, Vorgrundierung und einer mehrschichtigen Vorlackierung, bestehen. Hierbei ist von entscheidender Bedeutung, daß das erfindungsgemäße schmelztauchbeschichtete Stahlband durch die Erwärmung auf nur Schmelzbadtemperatur des eingesetzten Kaltbandes, auch nach der Lackierung, keine Alterung aufweist.After it has been cooled to about room temperature, the hot-dip coated tape is treated, stretch-oriented and chemically passivated or chemically pretreated and dried for a subsequent coating. The coating can in particular consist of a multi-layer structure, for example of sealing, pre-priming and a multi-layer pre-coating. It is of crucial importance that the hot-dip coated steel strip according to the invention has no aging due to the heating to only the melt bath temperature of the cold strip used, even after painting.

Die erfindungsgemäße Beschichtungsanlage weist einen unmittelbar vor dem Schmelztauchbad 4 angeordneten Erwärmungsofen 14 auf. In dem Ofen wird das Band auf im wesentlichen Schmelzbadtemperatur erwärmt. Bei einer Verzinkungsanlage beträgt die Oberflächentemperatur des Bandes im Ofen maximal 500 Grad Celsius. Bevorzugt wird eine Temperatur von 420 bis 500 Grad Celsius eingestellt. Hierdurch entfällt die bisher übliche Kühlung sowie die bisher übliche Überalterung. Ein Ausführungsbeispiel der Beschichtungsanlage wird anhand des in der beigefügten Abbildung schematisch dargestellten Ausführungsbeispieles erläutert.The coating system according to the invention has a heating furnace 14 arranged directly in front of the hot-dip bath 4. In the oven, the ribbon is heated to substantially melt bath temperature. In a galvanizing plant, the surface temperature of the strip in the furnace is a maximum of 500 degrees Celsius. A temperature of 420 to 500 degrees Celsius is preferably set. As a result, the previously customary cooling and the previously customary aging are eliminated. An embodiment of the coating system is explained with reference to the embodiment shown schematically in the attached figure.

Von dem Haspel 1 gelangt das Band über einen Bandspeicher 2 (Looper) über eine Entfettung mit Trocknung 3 in den Erwärmungsofen 14. Der Erwärmungsofen 14 ist bevorzugt ein Induktionsofen, der unmittelbar vor der Einführung des Bandes in das Schmelzbad 4 angeordnet ist. In dem Ofen wird von etwa Raumtemperatur (a) das Band zum Beispiel mit einer Aufheizgeschwindigkeit von 150 bis 300 Grad Celsius/Sekunde unter Schutzgas auf die gewünschte Temperatur (b) erwärmt und verläßt dann das Schmelzbad 4 mit etwa der Schmelzbadtemperatur (c). In einem weiteren Bandspeicher mit einer Kühleinheit kühlt das Band auf vorgegebene Temperaturen (d, e) ab, gelangt dann in ein Dressiergerüst 5, einen Streckrichter 6 und eine chemische Behandlung 7 mit Trockner 8. Daran anschließend können mehrere Beschichtungsschritte 9, 11 mit jeweiliger Trocknung 10, 12 erfolgen. Das fertig beschichtete Band wird auf einem Haspel 13 aufgewickelt.From the reel 1, the strip reaches the heating furnace 14 via a strip store 2 (looper) via degreasing and drying 3. The heating furnace 14 is preferably an induction furnace which is arranged immediately before the strip is introduced into the melting bath 4. In the furnace, the band is heated from about room temperature (a), for example at a heating rate of 150 to 300 degrees Celsius / second under protective gas, to the desired temperature (b) and then leaves the molten bath 4 at approximately the molten bath temperature (c). In a further strip store with a cooling unit, the strip cools down to predetermined temperatures (d, e), then passes into a skin pass mill 5, a stretching straightener 6 and a chemical treatment 7 with a dryer 8 10, 12 take place. The finished coated tape is wound on a reel 13.

Claims (7)

Verfahren zur Herstellung von schmelztauchbeschichtetem kaltgewalztem Stahlband, dadurch gekennzeichnet, daß
vor einer Tauchbeschichtung das Stahlband unter Schutzgas auf eine Temperatur unterhalb der Rekristallisationstemperatur auf nicht mehr als 420 bis 500 Grad Celsius erwärmt wird, wobei das Stahlband die folgende Zusammensetzung in Gewichtsprozenten aufweist: 0,02 bis 0,06 % Kohlenstoff, 0,01 bis 0,40 % Silizium, 0,10 bis 0,80 % Mangan, 0,005 bis 0,08 % Phosphor, 0,0005 bis 0,02 % Schwefel, 0,002 bis 0,009 % Stickstoff, 0,015 bis 0,08 % Aluminium, 0,01 bis 0,04 % Titan, max. 0,15 % von einem oder mehreren Elemente Kupfer, Vanadium, Nickel, Rest Eisen und unvermeidbare Verunreinigungen. Process for the production of hot-dip coated cold-rolled steel strip, characterized in that
Before an immersion coating, the steel strip is heated under protective gas to a temperature below the recrystallization temperature of not more than 420 to 500 degrees Celsius, the steel strip having the following composition in percent by weight: 0.02 to 0.06% carbon, 0.01 to 0.40% silicon, 0.10 to 0.80% manganese, 0.005 to 0.08% phosphorus, 0.0005 to 0.02% sulfur, 0.002 to 0.009% nitrogen, 0.015 to 0.08% aluminum, 0.01 to 0.04% titanium, Max. 0.15% of one or more elements copper, vanadium, nickel, Balance iron and unavoidable impurities. Schmelztauchbeschichtungsanlage, dadurch gekennzeichnet, daß unmittelbar vor dem Schmelztauchbad ein Erwärmungsofen angeordnet ist, in dem die Temperatur des Stahlbandes auf einen Wert unterhalb der Rekristallisationstemperatur, im wesentlichen auf nur die Temperatur des Schmelzbades eingestellt ist.Hot-dip coating installation, characterized in that a heating furnace is arranged directly in front of the hot-dip bath, in which the temperature of the steel strip is set to a value below the recrystallization temperature, essentially only to the temperature of the hot-melt bath. Beschichtungsanlage nach Anspruch 2, dadurch gekennzeichnet, daß die Temperatur im Erwärmungsofen bei einer Verzinkung maximal 500 Grad Celsius, insbesondere 420 bis 500 Grad Celsius beträgt.Coating plant according to claim 2, characterized in that the temperature in the heating furnace during galvanizing is a maximum of 500 degrees Celsius, in particular 420 to 500 degrees Celsius. Schmelztauchbeschichtetes Stahlband, erhältlich durch Haubenglühung des Kaltbandes und Erwärmung des Bandes vor der Tauchbeschichtung auf eine Temperatur, welche die Schmelzbadtemperatur nicht wesentlich überschreitet, insbesondere nicht größer als 500 Grad Celsius ist.Hot-dip coated steel strip, obtainable by annealing the cold strip and heating the strip before the dip coating to a temperature which does not substantially exceed the melting bath temperature, in particular not greater than 500 degrees Celsius. Schmelztauchbeschichtetes , kaltgewalztes Blech oder Band aus Stahl mit folgender Zusammensetzung in Gewichtsprozenten: 0,02 bis 0,06 % Kohlenstoff, vorzugsweise 0,03 bis 0,048 % Kohlenstoff, 0,01 bis 0,40 % Silizium, 0,10 bis 0,80 % Mangan, 0,005 bis 0,08 % Phosphor, 0,005 bis 0,02 % Schwefel, 0,002 bis 0,009 % Stickstoff 0,015 bis 0,08 % Aluminium, 0,01 bis 0,04 % Titan, max. 0,15 % von einem oder mehreren Elemente Kupfer, Vanadium, Nickel, Rest Eisen und unvermeidbare Verunreinigungen, erhältlich durch eine Erwärmung des rekristallisierend geglühten Bandes auf nicht mehr als 420 bis 500 Grad Celsius.Hot-dip coated, cold-rolled steel sheet or strip with the following composition in percent by weight: 0.02 to 0.06% carbon, preferably 0.03 to 0.048% carbon, 0.01 to 0.40% silicon, 0.10 to 0.80% manganese, 0.005 to 0.08% phosphorus, 0.005 to 0.02% sulfur, 0.002 to 0.009% nitrogen 0.015 to 0.08% aluminum, 0.01 to 0.04% titanium, Max. 0.15% of one or more elements copper, vanadium, nickel, Rest of iron and unavoidable impurities, obtainable by heating the recrystallized annealed strip to no more than 420 to 500 degrees Celsius. Schmelztauchbeschichtetes , kaltgewalztes Blech oder Band aus Stahl mit folgender Zusammensetzung in Gewichtsprozenten: 0,02 bis 0,06 % Kohlenstoff, vorzugsweise 0,03 bis 0,048 % Kohlenstoff, 0,01 bis 0,40 % Silizium, 0,10 bis 0,80 % Mangan, 0,005 bis 0,08 % Phosphor, 0,005 bis 0,02 % Schwefel, max. 0,009 % Stickstoff 0,015 bis 0,08 % Aluminium, 0,01 bis 0,04 % Titan, max. 0,15 % von einem oder mehreren Elemente Kupfer, Vanadium, Nickel, Rest Eisen und unvermeidbare Verunreinigungen, erhältlich durch Haspeln des Warmbandes bei weniger als 700 Grad Celsius und anschließendes Kaltwalzen und Glühen, wobei die Kaltwalzung in Abhängigkeit vom Titangehalt erfolgt und durch eine Erwärmung des Bandes auf nicht mehr als 420 bis 500 Grad Celsius.Hot-dip coated, cold-rolled steel sheet or strip with the following composition in percent by weight: 0.02 to 0.06% carbon, preferably 0.03 to 0.048% carbon, 0.01 to 0.40% silicon, 0.10 to 0.80% manganese, 0.005 to 0.08% phosphorus, 0.005 to 0.02% sulfur, Max. 0.009% nitrogen 0.015 to 0.08% aluminum, 0.01 to 0.04% titanium, Max. 0.15% of one or more elements copper, vanadium, nickel, Rest of iron and unavoidable impurities, obtainable by coiling the hot strip at less than 700 degrees Celsius and then cold rolling and annealing, the cold rolling taking place depending on the titanium content and by heating the strip to no more than 420 to 500 degrees Celsius. Verwendung eines schmelztauchbeschichteten kaltgewalzten Bleches oder Bandes aus Stahl nach den Ansprüchen 1 bis 6 für das Tiefziehen von Automobilteilen.Use of a hot-dip coated cold-rolled steel sheet or strip according to claims 1 to 6 for the deep drawing of automotive parts.
EP96116218A 1995-11-24 1996-10-10 Process and apparatus for hot dipping age resistant steel sheet Expired - Lifetime EP0775757B1 (en)

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