US20120279868A1 - Manufacturing galvannealed sheets by heat-treating electrolytically finished sheets - Google Patents

Manufacturing galvannealed sheets by heat-treating electrolytically finished sheets Download PDF

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Publication number
US20120279868A1
US20120279868A1 US13/505,253 US201013505253A US2012279868A1 US 20120279868 A1 US20120279868 A1 US 20120279868A1 US 201013505253 A US201013505253 A US 201013505253A US 2012279868 A1 US2012279868 A1 US 2012279868A1
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Prior art keywords
steel strip
zinc
strip
layer
sheets
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US13/505,253
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Johann Gerdenitsch
Josef Faderl
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Voestalpine Stahl GmbH
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Voestalpine Stahl GmbH
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Assigned to VOESTALPINE STAHL GMBH reassignment VOESTALPINE STAHL GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FADERL, JOSEF, GERDENITSCH, JOHANN
Publication of US20120279868A1 publication Critical patent/US20120279868A1/en
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated
    • C25D5/36—Pretreatment of metallic surfaces to be electroplated of iron or steel
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
    • C21D1/70—Temporary coatings or embedding materials applied before or during heat treatment while heating or quenching
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
    • C21D1/72—Temporary coatings or embedding materials applied before or during heat treatment during chemical change of surfaces
    • 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
    • C21D8/0478—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 involving a particular surface treatment
    • 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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/663—Bell-type furnaces
    • 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
    • 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
    • C23C28/021—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material including at least one metal alloy layer
    • 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
    • C23C28/023—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only
    • C23C28/025—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only with at least one zinc-based layer
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/48—After-treatment of electroplated surfaces
    • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/06—Wires; Strips; Foils
    • C25D7/0614—Strips or foils
    • 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
    • C21D2221/00—Treating localised areas of an article
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/22—Electroplating: Baths therefor from solutions of zinc

Definitions

  • the invention relates to a method for manufacturing coated steel sheets.
  • barrier protection coatings and cathodically acting protection coatings.
  • Barrier protection coatings are in particular protective coatings that are composed of aluminum, tin, or chromium; to produce them, for example an aluminum alloy is deposited onto a steel strip by means of a so-called hot-dip coating process.
  • the most widely used cathodically acting corrosion protection layer is a zinc coating; in particular, its action is based on the fact that when the zinc layer on the steel is damaged all the way down to the steel substrate, the zinc, as the chemically less noble metal, is corroded first, thus protecting the steel substrate.
  • Zinc coatings include pure zinc coatings, zinc coatings with a low aluminum content, zinc coatings with an aluminum content of about 5% (Galfan), and zinc aluminum coatings with approximately half zinc and half aluminum.
  • These coatings are likewise applied using the hot dipping method in which a preheated steel strip is conveyed through a bath of zinc or zinc alloy.
  • galvannealed layers represent a special case in which first, a hot-dip galvanization is used to deposit a zinc layer or zinc alloy layer onto a steel substrate and then an annealing step is carried out so that a diffusion reaction occurs between the zinc on the one hand and the iron of the steel substrate on the other so that a zinc/iron alloy layer forms.
  • a hot-dip galvanization is used to deposit a zinc layer or zinc alloy layer onto a steel substrate and then an annealing step is carried out so that a diffusion reaction occurs between the zinc on the one hand and the iron of the steel substrate on the other so that a zinc/iron alloy layer forms.
  • Such a layer is referred to as the galvannealed layer.
  • Such a galvannealed layer is produced at annealing temperatures of 480° C. to 600° C. in continuous annealing furnaces through which the strip passes after the galvanization.
  • DE 10 2007 031 91 96 A1 relates to a method for producing flexibly rolled strip stock with a cathodic corrosion protection layer; in this method, flexibly rolled material, i.e. steel strip with different steel strip thicknesses over its length, is among other things electrolytically galvanized and then annealed, with the annealing treatment being performed at ⁇ 420° C.
  • DE 10 2007 013 739 has disclosed a method for flexibly rolling coated steel strips; these steel strips can also be electrolytically galvanized and continuously annealed.
  • DE 10 2004 023 886 B4 has disclosed a method and an apparatus for finishing flexibly rolled strip stock in which flexibly rolled strip stock with a periodically varying material thickness is conveyed continuously through a processing line composed of an annealing section, a quenching unit, a preheating unit, and a zinc pot, and is thus heat treated and hot-dip galvanized; the inlet temperature of the flexibly rolled strip into the zinc pot is regulated to a constant value by varying the heat energy in the preheating unit as a function of the strip thickness and the zinc depositing thickness is regulated to a constant value by varying the distance of outlet nozzles from the flexibly rolled strip as a function of the strip thickness.
  • DE 10 2004 023 886 B4 has disclosed a method and an apparatus for finishing flexibly rolled strip stock in which the cold-rolled strip is to have a property profile that is matched to its thickness progression, where a first annealing treatment is carried out at a temperature between 500° C. and 600° C., after which the cold-rolled strip is rolled to a predefined thickness progression so that in the rolling direction, the flexible cold-rolled strip has at least one region of greater thickness and one region of lesser thickness; this is then followed by a second annealing treatment in which the temperature is higher than in the first annealing treatment.
  • galvannealed layer onto strips that have been flexibly rolled in this way.
  • the application of the galvannealed layer is usually carried out by means of a hot-dip galvanization followed by a continuous inline heat treatment. But this method cannot be used for providing a galvannealed coating to steel grades that are impossible or very expensive to manufacture by means of a hot-dip galvanization. These include isotropic steels, higher strength steels with strengths >1,000 MPa, and the aforementioned flexibly rolled strips.
  • the different sheet thicknesses result in both irregular mechanical properties and differing zinc/iron growth rates since in inline processes, the thick regions naturally heat up differently than the thin regions, necessarily resulting in correspondingly different diffusion speeds between zinc and iron.
  • the object of the invention is to create a method for manufacturing flexibly rolled or isotropic or higher strength galvannealing-coated steel strips.
  • a method for manufacturing a steel strip with a cathodic corrosion protection coating includes hot rolling the steel strip and subsequently cold rolling the steel strip; subjecting the steel strip to an electrolytic galvanization; and, after the electrolytic galvanization, heat treating the steel strip in a bell-type annealing furnace at temperatures of 250° C. to 350° C. for a period of 4 to 48 hours to produce a zinc/iron layer.
  • the method may also include flexibly cold rolling the steel strip in such a way that the steel strip has periodically different thicknesses and/or widths over its length and/or a steel strip with isotropic or higher-strength properties is used.
  • the flexibly rolled strip before the electrolytic galvanization, may be subjected to a recrystallization annealing at 550° C. to 650° C. in the bell-type annealing furnace or in a continuous annealing furnace.
  • a layer thickness of the electrolytically deposited zinc coating may be between 2 ⁇ m and 10 ⁇ m.
  • the method may also include annealing the steel strip in order to convert the zinc layer into a zinc/iron layer in such a way that the zinc/iron layer contains a maximum of 30% iron.
  • the problems arising due to different temperatures in the flexibly rolled strip are circumvented in that the strip is not hot-dip galvanized but instead electrolytically galvanized, thus avoiding different build-up heights of the zinc and iron phases due to temperature differences in the strip during the hot-dip galvanization.
  • the same approach can be used to avoid problems when hot-dip galvanizing isotropic or higher strength steels.
  • the galvannealed coating is produced not continuously in an inline fashion, but instead, the galvannealed layer formation takes place under protective gas in a bell-type annealing furnace.
  • the temperature of the annealing is reduced; according to the invention, temperatures of about 300° C. are maintained for holding times of approximately 20 hours.
  • the slow heating in the bell-type annealing furnace results in a uniform heating of the strip so that the zinc iron-reaction also occurs very uniformly in strip regions with different thicknesses.
  • a strip is flexibly cold rolled, is subjected to a recrystallization annealing in a bell-type annealing furnace at approximately 650° C. for 24 hours, following which the strip is then temper rolled and electrolytically galvanized and then undergoes a galvannealing step in the bell-type annealing furnace.
  • the invention therefore has the advantage that a steel strip with periodically varying sheet thickness (flexibly rolled strip (tailor rolled blank)) can be provided with a high-quality cathodic corrosion protection, which has good weldability; advantageously, both isotropic and higher strength steels as well as other steel grades can likewise be provided with a galvannealed layer.
  • steel sheets that are galvannealed according to the invention can be produced with very thin galvannealed coatings, which is made possible on the one hand by the electrolytic galvanization and on the other hand, by the gentle cooling.
  • isotropic steels and higher strength steels that can only be hot-dip galvanized with difficulty can be provided with a galvanized coating if the electrolytic galvanization is followed by the above-described bell-type annealing furnace step according to the invention.

Abstract

The invention relates to a method for manufacturing a steel strip with a cathodic corrosion protection coating, in which the steel strip is hot rolled and then cold rolled; the steel strip is subjected to an electrolytic galvanization and after the electrolytic galvanization, the steel strip is heat treated in a bell-type annealing furnace at temperatures of 250° C. to 350° C. for a period of 4 to 48 hours and this produces a zinc/iron layer.

Description

    FIELD OF THE INVENTION
  • The invention relates to a method for manufacturing coated steel sheets.
    • BACKGROUND OF THE INVENTION
  • It is known to produce steel sheets with a coating composed of a metal to protect the steel from corrosion.
  • These are basically divided into so-called barrier protection coatings and cathodically acting protection coatings.
  • Barrier protection coatings are in particular protective coatings that are composed of aluminum, tin, or chromium; to produce them, for example an aluminum alloy is deposited onto a steel strip by means of a so-called hot-dip coating process.
  • The most widely used cathodically acting corrosion protection layer is a zinc coating; in particular, its action is based on the fact that when the zinc layer on the steel is damaged all the way down to the steel substrate, the zinc, as the chemically less noble metal, is corroded first, thus protecting the steel substrate.
  • Zinc coatings include pure zinc coatings, zinc coatings with a low aluminum content, zinc coatings with an aluminum content of about 5% (Galfan), and zinc aluminum coatings with approximately half zinc and half aluminum.
  • These coatings are likewise applied using the hot dipping method in which a preheated steel strip is conveyed through a bath of zinc or zinc alloy.
  • So-called galvannealed layers represent a special case in which first, a hot-dip galvanization is used to deposit a zinc layer or zinc alloy layer onto a steel substrate and then an annealing step is carried out so that a diffusion reaction occurs between the zinc on the one hand and the iron of the steel substrate on the other so that a zinc/iron alloy layer forms. Such a layer is referred to as the galvannealed layer.
  • Such a galvannealed layer is produced at annealing temperatures of 480° C. to 600° C. in continuous annealing furnaces through which the strip passes after the galvanization.
  • DE 10 2007 031 91 96 A1 relates to a method for producing flexibly rolled strip stock with a cathodic corrosion protection layer; in this method, flexibly rolled material, i.e. steel strip with different steel strip thicknesses over its length, is among other things electrolytically galvanized and then annealed, with the annealing treatment being performed at <420° C.
  • DE 10 2007 013 739 has disclosed a method for flexibly rolling coated steel strips; these steel strips can also be electrolytically galvanized and continuously annealed.
  • DE 10 2004 023 886 B4 has disclosed a method and an apparatus for finishing flexibly rolled strip stock in which flexibly rolled strip stock with a periodically varying material thickness is conveyed continuously through a processing line composed of an annealing section, a quenching unit, a preheating unit, and a zinc pot, and is thus heat treated and hot-dip galvanized; the inlet temperature of the flexibly rolled strip into the zinc pot is regulated to a constant value by varying the heat energy in the preheating unit as a function of the strip thickness and the zinc depositing thickness is regulated to a constant value by varying the distance of outlet nozzles from the flexibly rolled strip as a function of the strip thickness.
  • DE 10 2004 023 886 B4 has disclosed a method and an apparatus for finishing flexibly rolled strip stock in which the cold-rolled strip is to have a property profile that is matched to its thickness progression, where a first annealing treatment is carried out at a temperature between 500° C. and 600° C., after which the cold-rolled strip is rolled to a predefined thickness progression so that in the rolling direction, the flexible cold-rolled strip has at least one region of greater thickness and one region of lesser thickness; this is then followed by a second annealing treatment in which the temperature is higher than in the first annealing treatment.
  • It is, however, problematic to apply a so-called galvannealed layer onto strips that have been flexibly rolled in this way. The application of the galvannealed layer is usually carried out by means of a hot-dip galvanization followed by a continuous inline heat treatment. But this method cannot be used for providing a galvannealed coating to steel grades that are impossible or very expensive to manufacture by means of a hot-dip galvanization. These include isotropic steels, higher strength steels with strengths >1,000 MPa, and the aforementioned flexibly rolled strips. Specifically with flexibly rolled strips in a hot-dip galvanizing system, the different sheet thicknesses result in both irregular mechanical properties and differing zinc/iron growth rates since in inline processes, the thick regions naturally heat up differently than the thin regions, necessarily resulting in correspondingly different diffusion speeds between zinc and iron.
  • There are other reasons, however, why manufacturing a flexibly rolled strip with a galvannealed coating in a hot-dip galvanizing system seems hardly feasible. Even with an induction galvannealing system, the required accuracy of the output control (variation of the coil power by a factor of up to two and more within a few centimeters of positioning accuracy) would be difficult to achieve.
  • The object of the invention is to create a method for manufacturing flexibly rolled or isotropic or higher strength galvannealing-coated steel strips.
    • SUMMARY OF THE INVENTION
  • According to the invention, a method for manufacturing a steel strip with a cathodic corrosion protection coating includes hot rolling the steel strip and subsequently cold rolling the steel strip; subjecting the steel strip to an electrolytic galvanization; and, after the electrolytic galvanization, heat treating the steel strip in a bell-type annealing furnace at temperatures of 250° C. to 350° C. for a period of 4 to 48 hours to produce a zinc/iron layer.
  • The method may also include flexibly cold rolling the steel strip in such a way that the steel strip has periodically different thicknesses and/or widths over its length and/or a steel strip with isotropic or higher-strength properties is used.
  • In certain embodiments, before the electrolytic galvanization, the flexibly rolled strip may be subjected to a recrystallization annealing at 550° C. to 650° C. in the bell-type annealing furnace or in a continuous annealing furnace.
  • A layer thickness of the electrolytically deposited zinc coating may be between 2 μm and 10 μm.
  • The method may also include annealing the steel strip in order to convert the zinc layer into a zinc/iron layer in such a way that the zinc/iron layer contains a maximum of 30% iron.
    • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • According to the invention, the problems arising due to different temperatures in the flexibly rolled strip are circumvented in that the strip is not hot-dip galvanized but instead electrolytically galvanized, thus avoiding different build-up heights of the zinc and iron phases due to temperature differences in the strip during the hot-dip galvanization. The same approach can be used to avoid problems when hot-dip galvanizing isotropic or higher strength steels.
  • Also according to the invention, the galvannealed coating is produced not continuously in an inline fashion, but instead, the galvannealed layer formation takes place under protective gas in a bell-type annealing furnace. Also according to the invention, the temperature of the annealing is reduced; according to the invention, temperatures of about 300° C. are maintained for holding times of approximately 20 hours.
  • The slow heating in the bell-type annealing furnace results in a uniform heating of the strip so that the zinc iron-reaction also occurs very uniformly in strip regions with different thicknesses.
  • According to the invention, a strip is flexibly cold rolled, is subjected to a recrystallization annealing in a bell-type annealing furnace at approximately 650° C. for 24 hours, following which the strip is then temper rolled and electrolytically galvanized and then undergoes a galvannealing step in the bell-type annealing furnace.
  • The invention therefore has the advantage that a steel strip with periodically varying sheet thickness (flexibly rolled strip (tailor rolled blank)) can be provided with a high-quality cathodic corrosion protection, which has good weldability; advantageously, both isotropic and higher strength steels as well as other steel grades can likewise be provided with a galvannealed layer.
  • It is also advantageous that steel sheets that are galvannealed according to the invention can be produced with very thin galvannealed coatings, which is made possible on the one hand by the electrolytic galvanization and on the other hand, by the gentle cooling.
  • According to the invention, isotropic steels and higher strength steels that can only be hot-dip galvanized with difficulty can be provided with a galvanized coating if the electrolytic galvanization is followed by the above-described bell-type annealing furnace step according to the invention.

Claims (5)

1. A method for manufacturing a steel strip with a cathodic corrosion protection coating, comprising:
hot rolling the steel strip and subsequently cold rolling the steel strip;
subjecting the steel strip to an electrolytic galvanization; and
after the electrolytic galvanization, heat treating the steel strip in a bell-type annealing furnace at temperatures of 250° C. to 350° C. for a period of 4 to 48 hours to produce a zinc/iron layer.
2. The method as recited in claim 1, comprising flexibly cold rolling the steel strip in such a way that the steel strip has periodically different thicknesses and/or widths over its length and/or a steel strip with isotropic or higher-strength properties is used.
3. The method as recited in claim 1, wherein before the electrolytic galvanization, the flexibly rolled strip is subjected to a recrystallization annealing at 550° C. to 650° C. in the bell-type annealing furnace or in a continuous annealing furnace.
4. The method as recited in claim 1, wherein a layer thickness of the electrolytically deposited zinc coating is between 2 μm and 10 μm.
5. The method as recited in claim 4, comprising annealing the steel strip in order to convert the zinc layer into a zinc/iron layer in such a way that the zinc/iron layer contains a maximum of 30% iron.
US13/505,253 2009-11-03 2010-09-13 Manufacturing galvannealed sheets by heat-treating electrolytically finished sheets Abandoned US20120279868A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102009051673.5-45 2009-11-03
DE102009051673A DE102009051673B3 (en) 2009-11-03 2009-11-03 Production of galvannealed sheets by heat treatment of electrolytically finished sheets
PCT/EP2010/063351 WO2011054571A1 (en) 2009-11-03 2010-09-13 Manufacturing galvannealed sheets by heat-treating electrolytically finished sheets

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US20120279868A1 true US20120279868A1 (en) 2012-11-08

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US (1) US20120279868A1 (en)
EP (1) EP2496721B8 (en)
JP (1) JP2013510233A (en)
KR (1) KR20130004234A (en)
CN (1) CN102712961A (en)
DE (1) DE102009051673B3 (en)
WO (1) WO2011054571A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140134450A1 (en) * 2012-11-14 2014-05-15 Muhr Und Bender Kg Method for Manufacturing a Product from a Flexibly Rolled Strip Material
WO2015007723A1 (en) 2013-07-16 2015-01-22 Rautaruukki Oyj Method of manufacturing a galvannealed steel strip product for hot press forming, method of manufacturing a hot-pressed steel component, and galvannealed steel strip product
WO2019215131A1 (en) * 2018-05-08 2019-11-14 Tata Steel Ijmuiden B.V. Variably rolled steel strip, sheet or blank and production method therefor
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US10710132B2 (en) 2015-09-30 2020-07-14 Thyssenkrupp Steel Europe Ag Manufacture of semi-finished products and structural components with locally different material thicknesses
WO2020221628A1 (en) * 2019-04-30 2020-11-05 Tata Steel Ijmuiden B.V. Process for producing batch annealed tailor rolled strip

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012085247A2 (en) * 2010-12-24 2012-06-28 Voestalpine Stahl Gmbh Method for producing hardened structural elements
DE102013010025A1 (en) * 2013-06-17 2014-12-18 Muhr Und Bender Kg Method for producing a product from flexibly rolled strip material
DE102015112889A1 (en) * 2015-08-05 2017-02-09 Salzgitter Flachstahl Gmbh High-strength manganese-containing steel, use of the steel for flexibly rolled flat steel products and production methods together with flat steel product for this purpose
DE102016102723B3 (en) 2016-02-16 2017-06-01 Salzgitter Flachstahl Gmbh Tempering roller, method for applying a flat product hereby and flat product thereof
CN109487307A (en) * 2018-12-28 2019-03-19 凡登（常州）新型金属材料技术有限公司 A kind of zinc-coated wire and preparation method thereof
CN111719131A (en) * 2019-03-22 2020-09-29 宝山钢铁股份有限公司 Production process of variable-thickness steel plate with coating
EP3872231A1 (en) * 2020-02-28 2021-09-01 voestalpine Stahl GmbH Method for conditioning the surface of a metal strip coated with a zinc alloy corrosion protection layer

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0432538A (en) * 1990-05-28 1992-02-04 Nippon Steel Corp High r-value electrogalvanized clad steel sheet excellent in burring resistance and electrogalvanizing adhesion and its manufacture
JP2000096148A (en) * 1998-09-25 2000-04-04 Nkk Corp Production of galvanized steel sheet excellent in surface appearance
US6159622A (en) * 1996-02-22 2000-12-12 Sumitomo Metal Industries, Ltd. Galvannealed steel sheet and manufacturing method thereof
US6524408B1 (en) * 1998-08-09 2003-02-25 Thyssen Krupp Stahl Ag Method for producing load-optimized steel strips
JP2004225068A (en) * 2003-01-20 2004-08-12 Jfe Steel Kk Bell type annealing furnace
US20060179638A1 (en) * 2002-12-17 2006-08-17 Bernhard Engl Method for producing a steel product
WO2007082786A1 (en) * 2006-01-11 2007-07-26 Thyssenkrupp Steel Ag Galvanized rolling-hardened cold-rolled flat product and process for producing it

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS609895A (en) * 1983-06-27 1985-01-18 Sumitomo Metal Ind Ltd Manufacture of alloyed galvanized steel sheet
JPS62240791A (en) * 1986-04-14 1987-10-21 Nippon Kokan Kk <Nkk> Treatment for alloying steel strip electrically-galvanized on one side
JPH0621348B2 (en) * 1986-07-22 1994-03-23 日新製鋼株式会社 Alloyed zinc plated steel sheet and its manufacturing method
JP2950199B2 (en) * 1995-06-12 1999-09-20 株式会社神戸製鋼所 Electrogalvanized steel sheet and electrogalvanized steel sheet having excellent wood grain resistance, and methods for producing them
DE10041280C2 (en) * 2000-08-22 2003-03-06 Muhr & Bender Kg Method and device for flexible rolling of a metal strip
DE10055338C1 (en) * 2000-11-08 2002-03-07 Thyssenkrupp Stahl Ag Production of cold strip comprises hot rolling pre-material produced from steel, cold rolling hot strip to form cold strip, annealing at temperature which is lower than recrystallization temperature, cold deforming, and further annealing
DE10102932C1 (en) * 2001-01-23 2002-08-22 Salzgitter Ag Process for producing a cold-rolled steel strip or sheet and strip or sheet which can be produced by the process
EP2177641B1 (en) * 2003-07-29 2013-04-24 voestalpine Stahl GmbH Steel plate having a galvanized corrosion protection layer
DE102004023886B4 (en) * 2004-05-12 2007-04-12 Muhr Und Bender Kg Method and device for finishing flexibly rolled strip material
EP1624093A1 (en) * 2004-08-04 2006-02-08 Aluminal Oberflächentechnik GmbH & Co. KG Coating of substrates of light metals or light metal alloys
DE102005045780A1 (en) * 2005-09-23 2007-04-12 Thyssenkrupp Steel Ag Method for producing a corrosion-protected flat steel product
CN100473738C (en) * 2006-05-25 2009-04-01 宝山钢铁股份有限公司 Solution strengthening isotropical steel and preparation method thereof
DE102006039307B3 (en) * 2006-08-22 2008-02-21 Thyssenkrupp Steel Ag Process for coating a 6-30 wt.% Mn-containing hot or cold rolled steel strip with a metallic protective layer
DE102007013739B3 (en) * 2007-03-22 2008-09-04 Voestalpine Stahl Gmbh Flexible rolling process to manufacture sheet metal component after hot or cold dipping and further mechanical and/or chemical treatment
DE102007019196A1 (en) * 2007-04-20 2008-10-23 Muhr Und Bender Kg Rolling process to make a flexible ribbon with a cathode anti-corrosion coating on hot dipped or electro-galvanized steel
EP2045360B1 (en) * 2007-10-02 2011-11-30 ThyssenKrupp Steel Europe AG Method for manufacturing a steel part by hot forming and steel part manufactured by hot forming

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0432538A (en) * 1990-05-28 1992-02-04 Nippon Steel Corp High r-value electrogalvanized clad steel sheet excellent in burring resistance and electrogalvanizing adhesion and its manufacture
US6159622A (en) * 1996-02-22 2000-12-12 Sumitomo Metal Industries, Ltd. Galvannealed steel sheet and manufacturing method thereof
US6524408B1 (en) * 1998-08-09 2003-02-25 Thyssen Krupp Stahl Ag Method for producing load-optimized steel strips
JP2000096148A (en) * 1998-09-25 2000-04-04 Nkk Corp Production of galvanized steel sheet excellent in surface appearance
US20060179638A1 (en) * 2002-12-17 2006-08-17 Bernhard Engl Method for producing a steel product
JP2004225068A (en) * 2003-01-20 2004-08-12 Jfe Steel Kk Bell type annealing furnace
WO2007082786A1 (en) * 2006-01-11 2007-07-26 Thyssenkrupp Steel Ag Galvanized rolling-hardened cold-rolled flat product and process for producing it
US20100159276A1 (en) * 2006-01-11 2010-06-24 Thyssenkrupp Steel Ag Galvanized rolling-hardened cold-rolled flat product and process for producing it

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Kollarova et al., "Phase Development in Post-Dip Annealed Zinc Coatings on Steel Sheets", Metal (15-17 May 2001), Ostrava, Czech Republic, pp. 1-6. *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140134450A1 (en) * 2012-11-14 2014-05-15 Muhr Und Bender Kg Method for Manufacturing a Product from a Flexibly Rolled Strip Material
JP2014132110A (en) * 2012-11-14 2014-07-17 Muhr & Bender Kg Method for manufacturing a product consisting of a flexibly rolled strip material
JP2018083986A (en) * 2012-11-14 2018-05-31 ムール ウント ベンダー コマンディートゲゼルシャフトＭｕｈｒ ｕｎｄ Ｂｅｎｄｅｒ ＫＧ Process for producing product made from strip material which has undergone flexible rolling
WO2015007723A1 (en) 2013-07-16 2015-01-22 Rautaruukki Oyj Method of manufacturing a galvannealed steel strip product for hot press forming, method of manufacturing a hot-pressed steel component, and galvannealed steel strip product
US10526680B2 (en) 2014-01-17 2020-01-07 Aperam Method for manufacturing a strip having a variable thickness and associated strip
US10710132B2 (en) 2015-09-30 2020-07-14 Thyssenkrupp Steel Europe Ag Manufacture of semi-finished products and structural components with locally different material thicknesses
WO2019215131A1 (en) * 2018-05-08 2019-11-14 Tata Steel Ijmuiden B.V. Variably rolled steel strip, sheet or blank and production method therefor
WO2020221628A1 (en) * 2019-04-30 2020-11-05 Tata Steel Ijmuiden B.V. Process for producing batch annealed tailor rolled strip

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