EP0946777B1 - METHOD OF HEAT-TREATING THIN SHEET COATED WITH ZnAl BY HOT DIP GALVANIZATION - Google Patents

METHOD OF HEAT-TREATING THIN SHEET COATED WITH ZnAl BY HOT DIP GALVANIZATION Download PDF

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Publication number
EP0946777B1
EP0946777B1 EP97942907A EP97942907A EP0946777B1 EP 0946777 B1 EP0946777 B1 EP 0946777B1 EP 97942907 A EP97942907 A EP 97942907A EP 97942907 A EP97942907 A EP 97942907A EP 0946777 B1 EP0946777 B1 EP 0946777B1
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EP
European Patent Office
Prior art keywords
thin sheet
coating
hot dip
znal
heat
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EP97942907A
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German (de)
French (fr)
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EP0946777A1 (en
Inventor
Hans-Joachim Heiler
Wilhelm Warnecke
Wilhelm DÜRR
Günther HÖBELHEINRICH
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ThyssenKrupp Steel Europe AG
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ThyssenKrupp Stahl AG
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    • 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
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • 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
    • C23C2/26—After-treatment
    • C23C2/261—After-treatment in a gas atmosphere, e.g. inert or reducing atmosphere
    • 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
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • C23C2/29—Cooling or quenching
    • 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
    • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36—Elongated material
    • C23C2/40—Plates; Strips

Definitions

  • the invention relates to a method for heat treatment of with an aluminum containing zinc alloy hot dip coated sheet.
  • Hot dip coating of thin sheet with zinc and / or aluminum or their alloys in continuous continuous processes are usually carried out such that the tape is melted by a bath of Coating material is passed. In doing so the surfaces of the tape with the coating material wetted. After leaving the coated tape the melt bath becomes excess melted Blow off coating material from the belt surface. The molten coating material cools and stiffens. The still warm coated tape can then then either cooled to room temperature or undergo further treatment. For example, hot-dip galvanized strip becomes one Subject to aging treatment. This is the tape annealed in the range around 350 ° C for about 3 min Improve deep-drawability (Stahl und Eisen 102 (1982) No. 24, page 1236).
  • WO-A-89/09844 describes a method for Heat treatment of a hot-dip coated steel sheet known in which a subsequent painting is provided is.
  • the coating according to this prior art In addition to zinc, the alloy used can contain 0.3 to 3.5% by weight. Aluminum included.
  • Process performed heat treatment is such composite coating of the steel sheet Temperatures above the melting point of the coating warmed up. Temperatures between 420 and 560 ° C for a coating of 0.5% Al, 0.005% Pb, 0.01% Si and the balance is zinc. By doing this the smoothness of the surface of the coating is improved.
  • Enamel or lacquer layer is also a warming of the coated tape to a temperature above 300 ° C to below the temperature of alloy formation for less than 5 minutes have been proposed (EP 0 710 732 A1). This is supposed to be micropores in the lacquer or enamel layer be avoided.
  • the ZnAl melt used according to the invention is concerned it is a ZnAl alloy, which in addition to zinc as Main component still 3.5 - 15% Al as well as traces of contains rare earths. In addition, there can still be traces of magnesium, manganese, copper or silicon his.
  • composition of the ZnAl melt is conditional Solidification behavior, which on the coating surface too "Grain boundary dents" This formation of the grain boundaries leads to a Impairment of the surface appearance. This will the application of the material for applications with high Surface quality requirements limited. Such areas of application arise in household appliances and in the automobile body after the forming and joining be provided with a sophisticated paint job.
  • the object of the present invention is now based on the surface formation of the ZnAl coating so to improve that after cold forming in connection with a paint or other coating process (Chromating, phosphating, protective lacquer sealing) a high quality surface is available.
  • this object is achieved by a method for heat treatment with a 3.5 to 15 mass% Zinc-based alloy containing aluminum hot-dip coated thin sheet solved, the immediately after solidification in the hot-dip bath its surface applied coating on a 20th up to 100 ° C above the liquidus temperature of the Coating material lying temperature 2 to 10 s warmed for a long time and then cooled to room temperature becomes.
  • Heat treated coating will also be a noticeable Improvement of the surface appearance as a result of Reduction in the grain boundary depth found at ZnAl coatings without using the invention Reheating is clearly pronounced.
  • the otherwise flower structure is macroscopically blurred and is not after enamelling or painting more recognizable.
  • the inventive method is therefore the application for Thin sheets proposed with a coating from a Zinc-based alloy containing 4.5 to 5.5% Al are coated.
  • a preferred heating takes place according to the invention electroinductive way. This way Temperature and duration of heating very fine regulate.
  • Another object of the invention is formability with an aluminum-based zinc-based alloy to improve hot dip coated sheet metal so that the formation of cracks during the forming process is avoided.
  • hot-dip coated thin sheets tend for cracking. So far, this problem has not been possible be solved satisfactorily.
  • hot-dip coated thin sheets are suitable especially for purposes with high demands on the Surface quality. This is especially true for home appliances and automotive body parts the case after forming and joining with a demanding Painting, chromating, phosphating, Protective lacquer sealing, enamelling or the like Surface coating.
  • the ribbon is first subjected to a cleaning process. This happens either in a direct burning furnace Heating of the belt surface and non-oxidizing Driving style. At the end of this treatment, the Belt temperature around 650 ° C.
  • one chemical pretreatment of the tape e.g. B. alkaline Cleaning.
  • the belt then passes through an oven area, in which it recrystallizes at temperatures of around 750 ° C to improve the cold formability.
  • this is also used as a reduction furnace designated furnace area due to the furnace atmosphere, the e.g. B. contains about 65% hydrogen, the rest nitrogen existing iron oxides on the strip surface are reduced. So is a good wetting through the molten metal prepared.
  • the band temperature Before immersing the tape in Metal smelting is the band temperature in one area lowered from 500 to 580 ° C.
  • the band is held under a so-called trunk Exclusion of air led into the hot-dip coating bath.
  • the proboscis is used to warm the band inside Radiators. This will be in the trunk Temperatures of around 800 ° C reached.
  • the zinc melt containing 5% by mass of Al is 430 ° C. on average.
  • a nozzle pressure of about 0.3 bar is set. Air or nitrogen can be used as the blow-off medium. When blowing off, the previously molten coating material solidifies.

Abstract

A thin sheet is coated by hot dip galvanization with a zinc based alloy comprising 3.5% to 15% by weight of aluminum. Immediately after solidification of the coating, the thin sheet is heated for 2 to 10 seconds to a temperature 20 to 100° C. above the melting point of the coating. The thin sheet is then cooled to room temperature.

Description

Die Erfindung betrifft ein Verfahren zum Wärmebehandeln von mit einer Aluminium enthaltenden Zinklegierung schmelztauchbeschichtetem Feinblech.The invention relates to a method for heat treatment of with an aluminum containing zinc alloy hot dip coated sheet.

Das Schmelztauchbeschichten von Feinblech mit Zink und/oder Aluminium bzw. mit deren Legierungen im kontinuierlichen Durchlaufverfahren erfolgt üblicherweise derart, daß das Band durch ein Bad des geschmolzenen Beschichtungsmaterials hindurchgeführt wird. Dabei werden die Oberflächen des Bandes mit dem Beschichtungsmaterial benetzt. Nach dem Verlassen des beschichteten Bandes aus dem Schmelztauchbad wird überschüssiges geschmolzenes Beschichtungsmaterial von der Bandoberfläche abgeblasen. Dabei kühlt das geschmolzene Beschichtungsmaterial ab und erstarrt. Das noch warme beschichtete Band kann dann anschließend entweder auf Raumtemperatur abgekühlt oder einer weiteren Behandlung unterworfen werden. Beispielsweise wird feuerverzinktes Band einer Überalterungsbehandlung unterworfen. Dazu wird das Band im Bereich um 350 °C etwa 3 min lang geglüht, um seine Tiefziehbarkeit zu verbessern (Stahl und Eisen 102 (1982) Nr. 24, Seite 1236). Hot dip coating of thin sheet with zinc and / or aluminum or their alloys in continuous continuous processes are usually carried out such that the tape is melted by a bath of Coating material is passed. In doing so the surfaces of the tape with the coating material wetted. After leaving the coated tape the melt bath becomes excess melted Blow off coating material from the belt surface. The molten coating material cools and stiffens. The still warm coated tape can then then either cooled to room temperature or undergo further treatment. For example, hot-dip galvanized strip becomes one Subject to aging treatment. This is the tape annealed in the range around 350 ° C for about 3 min Improve deep-drawability (Stahl und Eisen 102 (1982) No. 24, page 1236).

Aus der WO-A-89/09844 ist ein Verfahren zur Wärmebehandlung eines heißtauchüberzogenen Stahlblechs bekannt, bei dem eine anschließende Lackierung vorgesehen ist. Die gemäß diesem Stand der Technik zur Beschichtung verwendete Legierung kann neben Zink 0,3 bis 3,5 Gew.-% Aluminium enthalten. Im Zuge der gemäß dem bekannten Verfahren durchgeführten Wärmebehandlung wird die derart zusammengesetzte Beschichtung des Stahlblechs auf Temperaturen oberhalb des Schmelzpunktes der Beschichtung erwärmt. Dabei werden Temperaturen zwischen 420 und 560 °C für einen Überzug aus 0,5 % Al, 0,005 % Pb, 0,01 % Si und als Rest Zink erreicht. Durch diese Vorgehensweise wird die Glätte der Oberfläche des Überzuges verbessert. WO-A-89/09844 describes a method for Heat treatment of a hot-dip coated steel sheet known in which a subsequent painting is provided is. The coating according to this prior art In addition to zinc, the alloy used can contain 0.3 to 3.5% by weight. Aluminum included. In the course of the known Process performed heat treatment is such composite coating of the steel sheet Temperatures above the melting point of the coating warmed up. Temperatures between 420 and 560 ° C for a coating of 0.5% Al, 0.005% Pb, 0.01% Si and the balance is zinc. By doing this the smoothness of the surface of the coating is improved.

Zur Verbesserung der Oberflächenqualität einer auf verzinktes oder aluminiertes Feinblech aufgebrachten Email- oder Lackschicht ist auch schon eine Erwärmung des beschichteten Bandes auf eine Temperatur über 300 °C bis unterhalb der Temperatur der Legierungsbildung für weniger als 5 min vorgeschlagen worden (EP 0 710 732 A1). Dadurch sollen Mikroporen in der Lack- oder Emailschicht vermieden werden.To improve the surface quality of a galvanized or aluminized sheet Enamel or lacquer layer is also a warming of the coated tape to a temperature above 300 ° C to below the temperature of alloy formation for less than 5 minutes have been proposed (EP 0 710 732 A1). This is supposed to be micropores in the lacquer or enamel layer be avoided.

Bei der erfindungsgemäß verwendeten ZnAl-Schmelze handelt es sich um eine ZnAl-Legierung, die neben Zink als Hauptbestandteil noch 3,5 - 15 % Al sowie Spuren von seltenen Erden enthält. Darüber hinaus können noch Spuren von Magnesium, Mangan, Kupfer oder Silizium enthalten sein.The ZnAl melt used according to the invention is concerned it is a ZnAl alloy, which in addition to zinc as Main component still 3.5 - 15% Al as well as traces of contains rare earths. In addition, there can still be traces of magnesium, manganese, copper or silicon his.

Die Zusammensetzung der ZnAl-Schmelze bedingt ein Erstarrungsverhalten, das an der Überzugsfläche zu "eingefallenen" Korngrenzen ("grain boundary dents") führt Diese Ausbildung der Korngrenzen führt zu einer Beeinträchtigung des Oberflächenaussehens. Dadurch wird die Anwendung des Werkstoffes für Einsatzzwecke mit hohen Ansprüchen an die Oberflächenqualität eingeschränkt. Solche Einsatzgebiete ergeben sich bei Hausgeräten und in der Automobilkarosserie, die nach dem Umformen und Fügen mit einer anspruchsvollen Lackierung versehen werden.The composition of the ZnAl melt is conditional Solidification behavior, which on the coating surface too "Grain boundary dents" This formation of the grain boundaries leads to a Impairment of the surface appearance. This will the application of the material for applications with high Surface quality requirements limited. Such areas of application arise in household appliances and in the automobile body after the forming and joining be provided with a sophisticated paint job.

Der vorliegenden Erfindung liegt nun die Aufgabe zugrunde, die Oberflächenausbildung des ZnAl-Überzuges so zu verbessern, daß nach der Kaltumformung in Verbindung mit einer Lackierung oder anderen Beschichtungsverfahren (Chromatierung, Phosphatierung, Schutzlackversiegelung) eine qualitativ hochwertige Oberfläche vorliegt. The object of the present invention is now based on the surface formation of the ZnAl coating so to improve that after cold forming in connection with a paint or other coating process (Chromating, phosphating, protective lacquer sealing) a high quality surface is available.

Diese Aufgabe wird erfindungsgemäß durch ein Verfahren zur Wärmebehandlung von mit einer 3,5 bis 15 Masse-% Aluminium enthaltenden Zinkbasislegierung schmelztauchbeschichtetem Feinblech gelöst, das unmittelbar nach dem Erstarren der im Schmelztauchbad auf seine Oberflächen aufgebrachten Beschichtung auf eine 20 bis 100 °C über der Liquidustemperatur des Beschichtungsmaterials liegende Temperatur 2 bis 10 s lang erwärmt und danach auf Raumtemperatur abgekühlt wird.According to the invention, this object is achieved by a method for heat treatment with a 3.5 to 15 mass% Zinc-based alloy containing aluminum hot-dip coated thin sheet solved, the immediately after solidification in the hot-dip bath its surface applied coating on a 20th up to 100 ° C above the liquidus temperature of the Coating material lying temperature 2 to 10 s warmed for a long time and then cooled to room temperature becomes.

Am fertigen Feinblech mit dem erfindungsgemäß wärmebehandelten Überzug wird außerdem eine merkliche Verbesserung des Oberflächenaussehens infolge einer Verringerung der Korngrenzentiefe festgestellt, die bei ZnAl-Überzügen ohne Anwendung des erfindungsgemäßen Nacherwärmens deutlich ausgeprägt ist. Die sonst auftretende Blumenstruktur wird makroskopisch verwischt und ist nach einer Emaillierung oder Lackierung nicht mehr erkennbar.On the finished sheet with the invention Heat treated coating will also be a noticeable Improvement of the surface appearance as a result of Reduction in the grain boundary depth found at ZnAl coatings without using the invention Reheating is clearly pronounced. The otherwise flower structure is macroscopically blurred and is not after enamelling or painting more recognizable.

Mit dieser makroskopisch erkennbaren Veränderung geht auch eine mikroskopische Veränderung im Gefüge des ZnAl-Überzuges einher. Im Ausgangszustand besteht der typische Zn + 5 % Al-Überzug aus dem γ-Mischkristall und einem Eutektikum aus η- + β-Phase.With this macroscopically recognizable change goes also a microscopic change in the structure of the ZnAl coating hand in hand. In the initial state there is the typical one Zn + 5% Al coating from the γ mixed crystal and one Eutectic from η- + β phase.

Nach der erfindungsgemäßen Glühbehandlung tritt eine signifikante Änderung ein. Die ursprünglich groben η - Mischkristalle liegen nun fein verteilt und sehr zahlreich vor. Die an der ZnAl-Oberfläche vorliegenden Körner bilden sich durch die Wärmebehandlung neu und in signifikant kleinerer Korngröße aus. After the annealing treatment according to the invention, one occurs significant change. The originally rough ones η - mixed crystals are now finely distributed and very numerous before. The ones present on the ZnAl surface Grains form new and in through the heat treatment significantly smaller grain size.

Gemäß einer bevorzugten Ausgestaltung des erfindungsgemäßen Verfahrens wird daher die Anwendung für Feinbleche vorgeschlagen, die mit einem Überzug aus einer 4,5 bis 5,5 % Al enthaltenden Zinkbasislegierung beschichtet sind.According to a preferred embodiment of the The inventive method is therefore the application for Thin sheets proposed with a coating from a Zinc-based alloy containing 4.5 to 5.5% Al are coated.

Eine bevorzugte Erwärmung erfolgt erfindungsgemäß auf elektroinduktivem Weg. Auf diese Weise lassen sich Temperatur und Zeitdauer der Erwärmung sehr fein regulieren.A preferred heating takes place according to the invention electroinductive way. This way Temperature and duration of heating very fine regulate.

Eine weitere Aufgabe der Erfindung ist, die Umformbarkeit von mit einer aluminiumhaltigen Zinkbasislegierung schmelztauchbeschichtetem Feinblech so zu verbessern, daß die Bildung von Rissen beim Umformvorgang vermieden wird. Bekanntlich neigen schmelztauchbeschichtete Feinbleche zur Rißbildung. Dieses Problem konnte bislang nicht zufriedenstellend gelöst werden.Another object of the invention is formability with an aluminum-based zinc-based alloy to improve hot dip coated sheet metal so that the formation of cracks during the forming process is avoided. As is well known, hot-dip coated thin sheets tend for cracking. So far, this problem has not been possible be solved satisfactorily.

Durch die erfindungsgemäße Wärmebehandlung wird das geschilderte Problem gelöst. Derart nachträglich wärmebehandelte schmelztauchbeschichtete Feinbleche zeigten nach einer Umformung erheblich weniger und nur kleinere Risse.Through the heat treatment according to the invention problem described. So afterwards heat-treated hot-dip coated sheet metal showed significantly less and only after reshaping minor cracks.

Die nach den erfindungsgemäßen Verfahren wärmebehandelten schmelztauchbeschichteten Feinbleche eignen sich vor allem für Einsatzzwecke mit hohen Ansprüchen an die Oberflächenqualität. Dies ist insbesondere bei Hausgeräten und Automobilkarosserieteilen der Fall, die nach dem Umformen und Fügen mit einer anspruchsvollen Lackierung, Chromatierung, Phosphatierung, Schutzlackversiegelung, Emaillierung oder dergleichen Oberflächenbeschichtung versehen werden. Those heat-treated by the methods of the invention hot-dip coated thin sheets are suitable especially for purposes with high demands on the Surface quality. This is especially true for home appliances and automotive body parts the case after forming and joining with a demanding Painting, chromating, phosphating, Protective lacquer sealing, enamelling or the like Surface coating.

Beispielexample

Ein Band aus kaltgewalztem Feinblech aus einem vakuumentkohltem (ULC) Stahl der Abmessung 0,8 x 1.000 mm durchläuft mit einer Geschwindigkeit von 80 bis 100 m/min eine Feuerverzinkungsanlage, nachdem es am einlaufseitigen Abwickler an den Vorlaufring geschweißt und in die Verzinkungsanlage eingeführt wurde. Das Band wird zunächst einem Reinigungsprozeß unterzogen. Dies geschieht entweder in einem Abbrennofen mit direkter Beheizung der Bandoberfläche und nicht oxidierender Fahrweise. Am Ende dieser Behandlung beträgt die Bandtemperatur rund 650 °C. Alternativ kann auch eine chemische Vorbehandlung des Bandes, z. B. alkalische Reinigung, vorgenommen werden.A strip of cold rolled sheet from one vacuum decarburized (ULC) steel measuring 0.8 x 1,000 mm runs at a speed of 80 to 100 m / min a hot dip galvanizing line after it was on inlet-side unwinder welded to the feed ring and was introduced into the galvanizing plant. The ribbon is first subjected to a cleaning process. This happens either in a direct burning furnace Heating of the belt surface and non-oxidizing Driving style. At the end of this treatment, the Belt temperature around 650 ° C. Alternatively, one chemical pretreatment of the tape, e.g. B. alkaline Cleaning.

Anschließend durchläuft das Band einen Ofenbereich, in dem es bei Temperaturen von rund 750 °C rekristallisiert wird, um die Kaltumformbarkeit zu verbessern. Gleichzeitig werden in diesem auch als Reduktionsofen bezeichneten Ofenbereich aufgrund der Ofenatmosphäre, die z. B. rund 65 % Wasserstoff, Rest Stickstoff enthält, an der Bandoberfläche vorhandene Eisenoxide reduziert. So wird eine gute Benetzung durch die Metallschmelze vorbereitet. Vor dem Eintauchen des Bandes in Metallschmelze wird die Bandtemperatur in einen Bereich von 500 bis 580 °C abgesenkt.The belt then passes through an oven area, in which it recrystallizes at temperatures of around 750 ° C to improve the cold formability. At the same time, this is also used as a reduction furnace designated furnace area due to the furnace atmosphere, the e.g. B. contains about 65% hydrogen, the rest nitrogen existing iron oxides on the strip surface are reduced. So is a good wetting through the molten metal prepared. Before immersing the tape in Metal smelting is the band temperature in one area lowered from 500 to 580 ° C.

Das Band wird durch einen sogenannten Rüssel unter Luftabschluß in das Schmelztauchbeschichtungsbad geführt. Der Rüssel ist zur Erwärmung des Bandes innen mit Heizkörpern versehen. Dadurch werden im Rüssel Temperaturen von rund 800 °C erreicht. The band is held under a so-called trunk Exclusion of air led into the hot-dip coating bath. The proboscis is used to warm the band inside Radiators. This will be in the trunk Temperatures of around 800 ° C reached.

Die Temperatur der rd. 5 Masse-% Al enthaltenden Zinkschmelze beträgt im Mittel 430 °C. Zur Einstellung des Auflagengewichtes von z. B. 140 g/m2 und zum Abstreifen der überflüssigen Metallschmelze wird ein Düsendruck von rund 0,3 bar eingestellt. Als Abblasmedium kann Luft oder Stickstoff verwendet werden. Bei dem Abblasen erstarrt das zuvor schmelzflüssige Beschichtungsmaterial.The temperature of the approx. The zinc melt containing 5% by mass of Al is 430 ° C. on average. To adjust the weight of the z. B. 140 g / m 2 and for stripping the superfluous metal melt, a nozzle pressure of about 0.3 bar is set. Air or nitrogen can be used as the blow-off medium. When blowing off, the previously molten coating material solidifies.

Im noch warmen Zustand wird das schmelztauchbeschichtete Band der erfindungsgemäßen Wärmebehandlung im Durchlauf unterworfen. Dazu folgt eine kurzzeitige Erwärmung in der Größenordnung von 2 bis 10 s auf Temperaturen, die im Bereich von über 20 °C bis 100 °C oberhalb der LiquidusTemperatur des Beschichtungsmaterials liegt. Die Dauer der Erwärmung wird dabei so geregelt, daß es allenfalls partiell zum Wiederaufschmelzen des Beschichtungsmaterials auf dem Feinblech kommt. Die Glühung kann unter atmosphärischen Bedingungen erfolgen.It is hot-dip coated while still warm Belt of the heat treatment according to the invention in one pass subject. This is followed by a brief warming in the Order of magnitude of 2 to 10 s at temperatures in the Range from over 20 ° C to 100 ° C above the liquidus temperature of the coating material. The duration the warming is regulated so that it is at most partially for remelting the coating material comes on the thin sheet. The glow can under atmospheric conditions.

Abschließend erfolgt die übliche Dressierbehandlung, naß oder trocken, mit Dressiergraden von 0,3 bis 1,5 %.Finally, the usual skin treatment is carried out, wet or dry, with skin pass levels from 0.3 to 1.5%.

Fig. 1 und 2 zeigen Schliffbilder in der Vergrößerung 500 : 1.1 and 2 show micrographs in enlarged form 500: 1.

Die Rissbildung im Biegeschulterbereich des tiefgezogenen Napfes aus Material, welches nicht der erfindungsgemäßen Nacherwärmung unterworfen wurde, zeigt in Fig. 1 einen durch Pfeil gekennzeichneten großen tiefreichenden Riß. Demgegenüber sind am Schliffbild in Fig. 2 einer tiefgezogenen Napfprobe aus einem erfindungsgemäß nacherwärmten Material nach einer Tiefziehverformung nur kleinere unbedeutende Rißchen zu erkennen.The crack formation in the bending shoulder area of the deep-drawn Cups made of material that is not the invention Subsequent heating has been shown in Fig. 1 large deep crack marked by arrow. In contrast, the micrograph in Fig. 2 is one deep-drawn bowl sample from an inventive reheated material after deep drawing only recognizable minor insignificant cracks.

Claims (3)

  1. A process for the heat treatment of thin sheet metal coated by hot dip galvanisation with a zinc base alloy containing 3.5 to 15% by weight Al which, immediately after the solidification of the coating applied to its surfaces in the hot dip bath, is heated for 2 to 10 sec to a temperature 20 to 100°C above the liquidus temperature of the coating material and then cooled to room temperature.
  2. A process according to claim 1, wherein a thin sheet is heated which is coated with an alloy consisting of 4.5 to 5.5% by weight Al, residue Zn.
  3. A process according to claims 1 or 2, wherein the thin sheet is heated electro-inductively.
EP97942907A 1996-11-09 1997-09-03 METHOD OF HEAT-TREATING THIN SHEET COATED WITH ZnAl BY HOT DIP GALVANIZATION Expired - Lifetime EP0946777B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19646362 1996-11-09
DE19646362A DE19646362C2 (en) 1996-11-09 1996-11-09 Process for the heat treatment of ZnAl hot-dip coated thin sheet
PCT/EP1997/004787 WO1998021378A1 (en) 1996-11-09 1997-09-03 METHOD OF HEAT-TREATING THIN SHEET COATED WITH ZnAl BY HOT DIP GALVANIZATION

Publications (2)

Publication Number Publication Date
EP0946777A1 EP0946777A1 (en) 1999-10-06
EP0946777B1 true EP0946777B1 (en) 2001-07-11

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EP97942907A Expired - Lifetime EP0946777B1 (en) 1996-11-09 1997-09-03 METHOD OF HEAT-TREATING THIN SHEET COATED WITH ZnAl BY HOT DIP GALVANIZATION

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US (1) US6231695B1 (en)
EP (1) EP0946777B1 (en)
JP (1) JP2001504161A (en)
KR (1) KR20000053154A (en)
AT (1) ATE203062T1 (en)
AU (1) AU728356B2 (en)
CA (1) CA2270897A1 (en)
DE (2) DE19646362C2 (en)
ES (1) ES2161475T3 (en)
PL (1) PL184212B1 (en)
WO (1) WO1998021378A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NZ573913A (en) * 2006-05-24 2012-03-30 Bluescope Steel Ltd Treating al/zn-based alloy coated products
DE102012100509B4 (en) * 2012-01-23 2015-10-08 Thyssenkrupp Rasselstein Gmbh Process for refining a metallic coating on a steel strip
DE102013101847B3 (en) 2013-02-25 2014-03-27 Thyssenkrupp Rasselstein Gmbh Method for producing a corrosion-resistant steel sheet

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE225000C (en)
AT225000B (en) * 1960-11-09 1962-12-27 Armco Steel Corp Process for producing an essentially single-phase alloyed coating of zinc with a small amount of aluminum on a steel body or steel strip
JPS608289B2 (en) * 1978-10-16 1985-03-01 日新製鋼株式会社 Method for manufacturing hot-dip galvanized steel sheets with excellent workability
US4171392A (en) * 1978-11-08 1979-10-16 Inland Steel Company Process of producing one-side alloyed galvanized steel strip
AT365243B (en) * 1979-09-26 1981-12-28 Voest Alpine Ag METHOD FOR HOT-GALNIFYING IRON OR STEEL ITEMS
US4390377A (en) * 1981-01-12 1983-06-28 Hogg James W Novel continuous, high speed method of galvanizing and annealing a continuously travelling low carbon ferrous wire
JPS59104462A (en) * 1982-12-06 1984-06-16 Nisshin Steel Co Ltd Single surface molten metal plating method
JPS59145770A (en) * 1983-02-09 1984-08-21 Nisshin Steel Co Ltd One-side metal hot dipping method
JP2755387B2 (en) * 1988-04-12 1998-05-20 大洋製鋼株式会社 Manufacturing method of hot-dip zinc-alloy-plated steel sheet for pre-coated steel sheet and pre-coated steel sheet
US5015341A (en) * 1988-08-05 1991-05-14 Armco Steel Company, L.P. Induction galvannealed electroplated steel strip
FR2726578B1 (en) 1994-11-04 1996-11-29 Lorraine Laminage PROCESS FOR THE TEMPER COATING OF A STEEL SHEET WITH A METAL LAYER BASED ON ALUMINUM OR ZINC

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Publication number Publication date
ES2161475T3 (en) 2001-12-01
PL333106A1 (en) 1999-11-08
JP2001504161A (en) 2001-03-27
EP0946777A1 (en) 1999-10-06
ATE203062T1 (en) 2001-07-15
DE19646362C2 (en) 2000-07-06
CA2270897A1 (en) 1998-05-22
WO1998021378A1 (en) 1998-05-22
KR20000053154A (en) 2000-08-25
AU728356B2 (en) 2001-01-04
PL184212B1 (en) 2002-09-30
DE59704040D1 (en) 2001-08-16
DE19646362A1 (en) 1998-05-14
US6231695B1 (en) 2001-05-15
AU4457497A (en) 1998-06-03

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