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EP0946777A1 - 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

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Publication number
EP0946777A1
EP0946777A1 EP97942907A EP97942907A EP0946777A1 EP 0946777 A1 EP0946777 A1 EP 0946777A1 EP 97942907 A EP97942907 A EP 97942907A EP 97942907 A EP97942907 A EP 97942907A EP 0946777 A1 EP0946777 A1 EP 0946777A1
Authority
EP
European Patent Office
Prior art keywords
thin sheet
znal
heat
hot
coated
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP97942907A
Other languages
German (de)
French (fr)
Other versions
EP0946777B1 (en
Inventor
Hans-Joachim Heiler
Wilhelm Warnecke
Wilhelm DÜRR
Günther HÖBELHEINRICH
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ThyssenKrupp Steel Europe AG
Original Assignee
Thyssen Stahl AG
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Filing date
Publication date
Application filed by Thyssen Stahl AG filed Critical Thyssen Stahl AG
Publication of EP0946777A1 publication Critical patent/EP0946777A1/en
Application granted granted Critical
Publication of EP0946777B1 publication Critical patent/EP0946777B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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 the heat treatment of thin sheet coated with an aluminum-containing zinc alloy.
  • the hot dip coating of thin sheet with zinc and / or aluminum or with their alloys in a continuous continuous process is usually carried out in such a way that the strip is passed through a bath of the molten coating material.
  • the surfaces of the tape are wetted with the coating material.
  • excess molten coating material is blown off the surface of the strip.
  • the molten coating material cools down and solidifies.
  • the coated tape which is still warm, can then either be cooled to room temperature or subjected to a further treatment.
  • hot-dip galvanized strip is subjected to an aging treatment.
  • the strip is annealed in the range around 350 ° C.
  • the ZnAl melt used according to the invention is a ZnAl alloy which, in addition to zinc as the main constituent, also contains 3.5-15% Al and traces of rare earths. Traces of magnesium, manganese, copper or silicon may also be present.
  • composition of the ZnAl melt causes a solidification behavior, which leads to "grain boundary dents" on the coating surface. This formation of the grain boundaries leads to an impairment of the surface appearance. This limits the use of the material for applications with high demands on the surface quality. Such areas of application arise in household appliances and in the automobile body, which are provided with a sophisticated paint after forming and joining.
  • the present invention is based on the object of improving the surface formation of the ZnAl coating in such a way that a high-quality surface is present after the cold forming in conjunction with a coating or other coating processes (chromating, phosphating, protective lacquer sealing).
  • the invention seeks to remedy this and provides that the sheet immediately after the solidification of the coating applied to its surfaces in the hot-dip bath is heated to a temperature 20 to 100 ° C. above the liquidus temperature of the coating material for 2 to 10 s and then cooled to room temperature becomes.
  • a noticeable improvement in the surface appearance as a result of a reduction in the grain boundary depth is found on the finished sheet with the heat-treated coating according to the invention, which is clearly pronounced in ZnAl coatings without using the reheating according to the invention.
  • the otherwise occurring flower structure is macroscopically blurred and is no longer recognizable even after enamelling or painting.
  • This macroscopically recognizable change is accompanied by a microscopic change in the structure of the ZnAl coating.
  • the typical Zn + 5% Al coating consists of the V "mixed crystal and a eutectic of ⁇ - + ß phase.
  • the originally coarse ⁇ mixed crystal areas are now finely distributed and very numerous.
  • the grains present on the ZnAl surface are newly formed by the heat treatment and in a significantly smaller grain size.
  • the use for thin sheets is therefore proposed which are coated with a coating of a zinc-based alloy containing 4.5 to 5.5% Al.
  • a preferred heating takes place according to the invention by an electroinductive way. In this way, the temperature and duration of the heating can be regulated very finely.
  • a further object of the invention is to improve the formability of thin sheet hot-dip coated with an aluminum-containing zinc-based alloy in such a way that the formation of cracks during the forming process is avoided.
  • hot-dip coated sheet metal tends to crack. So far, this problem has not been solved satisfactorily.
  • the hot-dip coated thin sheets heat-treated by the processes according to the invention are particularly suitable for applications with high demands on the surface quality. This is particularly the case with household appliances and automobile body parts, which after forming and joining are provided with a sophisticated coating, chromating, phosphating, protective lacquer sealing, enamelling or similar surface coating. example
  • a strip of cold-rolled thin sheet made of a vacuum decarburized (ULC) steel measuring 0.8 x 1,000 mm passes through a hot-dip galvanizing line at a speed of 80 to 100 m / min after it has been welded to the feed ring on the inlet side unwinder and inserted into the galvanizing line.
  • the belt is first subjected to a cleaning process. This is done either in an incinerator with direct heating of the belt surface and a non-oxidizing mode of operation. At the end of this treatment, the belt temperature is around 650 ° C.
  • a chemical pretreatment of the belt e.g. B. alkaline cleaning.
  • the strip then passes through a furnace area in which it is recrystallized at temperatures of around 750 ° C in order to improve the cold formability.
  • this furnace area also referred to as a reduction furnace, due to the furnace atmosphere, which, for. B. contains about 65% hydrogen, the rest nitrogen, reduces iron oxides present on the strip surface. Good wetting is prepared by the molten metal.
  • the strip temperature is reduced to a range from 500 to 580 ° C.
  • the tape is fed through a so-called proboscis into the hot-dip coating bath with the exclusion of air.
  • the proboscis is equipped with radiators on the inside to heat the band.
  • temperatures of around 800 ° C are reached in the trunk.
  • the zinc melt containing 5% by mass of AI 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.
  • the hot-dip coated strip is subjected to the heat treatment according to the invention in one pass. This is followed by brief heating in the order of 2 to 10 s to temperatures which are in the range from above 20 ° C. to 100 ° C. above the liquidus temperature of the coating material. The duration of the heating is regulated in such a way that the coating material at most partially melts on the thin sheet. Annealing can take place under atmospheric conditions.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Thermal Sciences (AREA)
  • Coating With Molten Metal (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Abstract

The invention concerns a method of heat-treating thin sheet which has been coated with zinc and/or aluminium by hot dip galvanization. The invention is characterized in that, immediately after the coating applied to its surfaces in the hot dip bath has hardened, the thin sheet is heated for between 2 and 10 seconds to a temperature which is between 20 and 100 DEG C above the liquidus temperature of the coating material and is then cooled to ambient temperature.

Description

Verfahren zum Wärmebehandeln von ZnAl- schmelztauchbeschichtetem FeinblechProcess for the heat treatment of ZnAl hot-dip coated thin sheet
Die Erfindung betrifft ein Verfahren zum Wärmebehandeln von mit einer Aluminium enthaltenden Zinklegierung schmelztauchbeschichtetem Feinblech.The invention relates to a method for the heat treatment of thin sheet coated with an aluminum-containing zinc alloy.
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) . 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 AI) . Dadurch sollen Mikroporen in der Lack- oder Emailschicht vermieden werden.The hot dip coating of thin sheet with zinc and / or aluminum or with their alloys in a continuous continuous process is usually carried out in such a way that the strip is passed through a bath of the molten coating material. The surfaces of the tape are wetted with the coating material. After leaving the coated strip from the hot-dip bath, excess molten coating material is blown off the surface of the strip. The molten coating material cools down and solidifies. The coated tape, which is still warm, can then either be cooled to room temperature or subjected to a further treatment. For example, hot-dip galvanized strip is subjected to an aging treatment. For this purpose, the strip is annealed in the range around 350 ° C. for about 3 minutes in order to improve its deep-drawability (Stahl und Eisen 102 (1982) No. 24, page 1236). In order to improve the surface quality of an enamel or varnish layer applied to galvanized or aluminized thin sheet, heating of the coated strip to a temperature above 300 ° C. to below the temperature of the alloy formation for less than 5 minutes has also been proposed (EP 0 710 732 AI) . This is intended to avoid micropores in the lacquer or enamel layer.
Bei der erfindungsgemäß verwendeten ZnAl-Schmelze handelt es sich um eine ZnAl-Legierung, die neben Zink als Hauptbestandteil noch 3,5 - 15 % AI 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 a ZnAl alloy which, in addition to zinc as the main constituent, also contains 3.5-15% Al and traces of rare earths. Traces of magnesium, manganese, copper or silicon may also be present.
Die Zusammensetzung der ZnAl-Schmelze bedingt ein Erstarrungsverhalten, das an der Überzugsflache 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 causes a solidification behavior, which leads to "grain boundary dents" on the coating surface. This formation of the grain boundaries leads to an impairment of the surface appearance. This limits the use of the material for applications with high demands on the surface quality. Such areas of application arise in household appliances and in the automobile body, which are provided with a sophisticated paint after forming and joining.
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. Die Erfindung will hier Abhilfe schaffen und sieht vor, daß das Feinblech 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 für 2 bis 10 s erwärmt und danach auf Raumtemperatur abgekühlt wird.The present invention is based on the object of improving the surface formation of the ZnAl coating in such a way that a high-quality surface is present after the cold forming in conjunction with a coating or other coating processes (chromating, phosphating, protective lacquer sealing). The invention seeks to remedy this and provides that the sheet immediately after the solidification of the coating applied to its surfaces in the hot-dip bath is heated to a temperature 20 to 100 ° C. above the liquidus temperature of the coating material for 2 to 10 s and then cooled to room temperature becomes.
Am fertigen Feinblech mit dem erfindungsgemäß wärmebehandelten Überzug wird eine merkliche Verbesserung des Oberflächenaussehens infolge einer Verringerung der Korngrenzentiefe estgestellt, die bei ZnAl-Überzügen ohne Anwendung des erfindungsgemäßen Nacherwärmens deutlich ausgeprägt ist. Die sonst auftretende Blumenstruktur wird makroskopisch verwischt und ist auch nach einer Emaillierung oder Lackierung nicht mehr erkennbar.A noticeable improvement in the surface appearance as a result of a reduction in the grain boundary depth is found on the finished sheet with the heat-treated coating according to the invention, which is clearly pronounced in ZnAl coatings without using the reheating according to the invention. The otherwise occurring flower structure is macroscopically blurred and is no longer recognizable even after enamelling or painting.
Mit dieser makroskopisch erkennbaren Veränderung geht eine mikroskopische Veränderung im Gefüge des ZnAl- Überzuges einher. Im Ausgangszustand besteht der typische Zn + 5 % AI-Überzug aus dem V" -Mischkristall und einem Eutektikum aus η - + ß-Phase.This macroscopically recognizable change is accompanied by a microscopic change in the structure of the ZnAl coating. In the initial state, the typical Zn + 5% Al coating consists of the V "mixed crystal and a eutectic of η - + ß phase.
Nach der erfindungsgemäßen Glühbehandlung tritt eine signifikante Änderung ein. Die ursprünglich groben η - Mischkristallbereiche 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. 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 % AI enthaltenden Zinkbasislegierung beschichtet sind.A significant change occurs after the annealing treatment according to the invention. The originally coarse η mixed crystal areas are now finely distributed and very numerous. The grains present on the ZnAl surface are newly formed by the heat treatment and in a significantly smaller grain size. According to a preferred embodiment of the method according to the invention, the use for thin sheets is therefore proposed which are coated with a coating of a zinc-based alloy containing 4.5 to 5.5% Al.
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 by an electroinductive way. In this way, the temperature and duration of the heating can be regulated very finely.
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.A further object of the invention is to improve the formability of thin sheet hot-dip coated with an aluminum-containing zinc-based alloy in such a way that the formation of cracks during the forming process is avoided. As is well known, hot-dip coated sheet metal tends to crack. So far, this problem has not been 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.The described problem is solved by the heat treatment according to the invention. Subsequent heat-treated hot-dip coated thin sheets showed significantly less and only smaller cracks after forming.
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. BeispielThe hot-dip coated thin sheets heat-treated by the processes according to the invention are particularly suitable for applications with high demands on the surface quality. This is particularly the case with household appliances and automobile body parts, which after forming and joining are provided with a sophisticated coating, chromating, phosphating, protective lacquer sealing, enamelling or similar surface coating. example
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 thin sheet made of a vacuum decarburized (ULC) steel measuring 0.8 x 1,000 mm passes through a hot-dip galvanizing line at a speed of 80 to 100 m / min after it has been welded to the feed ring on the inlet side unwinder and inserted into the galvanizing line. The belt is first subjected to a cleaning process. This is done either in an incinerator with direct heating of the belt surface and a non-oxidizing mode of operation. At the end of this treatment, the belt temperature is around 650 ° C. Alternatively, a chemical pretreatment of the belt, 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 strip then passes through a furnace area in which it is recrystallized at temperatures of around 750 ° C in order to improve the cold formability. At the same time in this furnace area, also referred to as a reduction furnace, due to the furnace atmosphere, which, for. B. contains about 65% hydrogen, the rest nitrogen, reduces iron oxides present on the strip surface. Good wetting is prepared by the molten metal. Before the strip is immersed in molten metal, the strip temperature is reduced to a range 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. Die Temperatur der rd. 5 Masse-% AI 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 tape is fed through a so-called proboscis into the hot-dip coating bath with the exclusion of air. The proboscis is equipped with radiators on the inside to heat the band. As a result, temperatures of around 800 ° C are reached in the trunk. The temperature of the approx. The zinc melt containing 5% by mass of AI is 430 ° C. on average. To adjust the weight of the z. B. 140 g / m 2 and to strip off 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 Liquidus- Temperatur 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.While still warm, the hot-dip coated strip is subjected to the heat treatment according to the invention in one pass. This is followed by brief heating in the order of 2 to 10 s to temperatures which are in the range from above 20 ° C. to 100 ° C. above the liquidus temperature of the coating material. The duration of the heating is regulated in such a way that the coating material at most partially melts on the thin sheet. Annealing can take place under atmospheric conditions.
Abschließend erfolgt die übliche Dressierbehandlung, naß oder trocken, mit Dressiergraden von 0,3 bis 1,5 %.Finally, the usual skin pass treatment is carried out, wet or dry, with skin pass degrees of 0.3 to 1.5%.
Fig. 1 und 2 zeigen Schliffbilder in der Vergrößerung 500 : 1.1 and 2 show micrographs in the magnification 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 formation of cracks in the bending shoulder area of the deep-drawn cup made of material which was not subjected to the reheating according to the invention shows in Fig. 1 a large deep crack indicated by an arrow. In contrast, the micrograph in FIG. 2 of a deep-drawn cup sample made from a material reheated according to the invention after deep-drawing deformation shows only minor insignificant cracks.

Claims

P a t e n t a n s p r ü c h e: Patent claims:
1.) Verfahren zum Wärmebehandeln von mit einer aluminiumhaltigen Zinkbasislegierung schmelztauch- beschichtetem Feinblech, d a d u r c h g e k e n n z e i c h n e t, daß das Feinblech 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.1.) Process for the heat treatment of thin sheet coated with an aluminum-containing zinc-base alloy, characterized in that the thin sheet immediately after the solidification of the coating applied to its surfaces in the hot-dip bath to a temperature 2 to 10 ° C above the liquidus temperature of the coating material heated for s and then cooled to room temperature.
2.) Verfahren nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, daß ein2.) Method according to claim 1, d a d u r c h g e k e n n z e i c h n e t that a
Feinblech, beschichtet mit einer Legierung ausThin sheet coated with an alloy of
5 Masse-% AI, Rest Zn, für 2 bis 10 s auf 400 bis 480 °C erwärmt wird.5 mass% AI, rest Zn, is heated to 400 to 480 ° C for 2 to 10 s.
3. ) Verfahren nach den Ansprüchen 1 und 2 , d a d u r c h g e k e n n z e i c h n e t, daß das Feinblech auf elektroinduktivem Weg erwärmt wird.3.) Process according to claims 1 and 2, d a d u r c h g e k e n n z e i c h n e t that the thin sheet is heated in an electro-inductive way.
4.) Verfahren nach einem der Ansprüche 1 bis 3, d a d u r c h g e k e n n z e i c h n e t, daß das Feinblech vor der Wärmebehandlung mit einer 3,5 - 15 % AI als Hauptbestandteil der Zinkbasislegierung schmelztauchbeschichtet wird. 4.) Method according to one of claims 1 to 3, d a d u r c h g e k e n n e e c h e n that the thin sheet is hot-dip coated with a 3.5 - 15% Al as the main component of the zinc-based alloy before the heat treatment.
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
DE19646362A DE19646362C2 (en) 1996-11-09 1996-11-09 Process for the heat treatment of ZnAl hot-dip coated thin sheet
DE19646362 1996-11-09
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 true EP0946777A1 (en) 1999-10-06
EP0946777B1 EP0946777B1 (en) 2001-07-11

Family

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Family Applications (1)

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

Country Status (11)

Country Link
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)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2652936C (en) * 2006-05-24 2014-09-30 Bluescope Steel Limited 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

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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

Non-Patent Citations (1)

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Title
See references of WO9821378A1 *

Also Published As

Publication number Publication date
PL184212B1 (en) 2002-09-30
AU4457497A (en) 1998-06-03
EP0946777B1 (en) 2001-07-11
AU728356B2 (en) 2001-01-04
DE19646362A1 (en) 1998-05-14
ES2161475T3 (en) 2001-12-01
WO1998021378A1 (en) 1998-05-22
CA2270897A1 (en) 1998-05-22
PL333106A1 (en) 1999-11-08
JP2001504161A (en) 2001-03-27
DE19646362C2 (en) 2000-07-06
ATE203062T1 (en) 2001-07-15
DE59704040D1 (en) 2001-08-16
US6231695B1 (en) 2001-05-15
KR20000053154A (en) 2000-08-25

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