EP4296399A1 - Procédé de fabrication d'une tôle d'acier revêtue par immersion à chaud et tôle d'acier revêtue par immersion à chaud - Google Patents

Procédé de fabrication d'une tôle d'acier revêtue par immersion à chaud et tôle d'acier revêtue par immersion à chaud Download PDF

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Publication number
EP4296399A1
EP4296399A1 EP23180236.4A EP23180236A EP4296399A1 EP 4296399 A1 EP4296399 A1 EP 4296399A1 EP 23180236 A EP23180236 A EP 23180236A EP 4296399 A1 EP4296399 A1 EP 4296399A1
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EP
European Patent Office
Prior art keywords
steel sheet
hot
coating
stripping
dip coated
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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.)
Pending
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EP23180236.4A
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German (de)
English (en)
Inventor
Jennifer Schulz
Fabian JUNGE
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ThyssenKrupp Steel Europe AG
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ThyssenKrupp Steel Europe AG
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Publication of EP4296399A1 publication Critical patent/EP4296399A1/fr
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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
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • 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
    • C23C2/14—Removing excess of molten coatings; Controlling or regulating the coating thickness
    • C23C2/16—Removing excess of molten coatings; Controlling or regulating the coating thickness using fluids under pressure, e.g. air knives
    • C23C2/18—Removing excess of molten coatings from elongated material
    • C23C2/20—Strips; Plates
    • 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
    • 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
    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
    • C23C22/08—Orthophosphates
    • C23C22/18—Orthophosphates containing manganese cations
    • C23C22/182—Orthophosphates containing manganese cations containing also zinc cations
    • C23C22/184—Orthophosphates containing manganese cations containing also zinc cations containing also nickel cations
    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/78—Pretreatment of the material to be coated
    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/78—Pretreatment of the material to be coated
    • C23C22/80—Pretreatment of the material to be coated with solutions containing titanium or zirconium compounds
    • 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • C23G1/081—Iron or steel solutions containing H2SO4
    • 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/10—Other heavy metals
    • 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
    • C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
    • C23C2222/20—Use of solutions containing silanes

Definitions

  • the invention relates to a method for producing a hot-dip coated steel sheet, the method comprising the following steps: providing a steel sheet; Hot-dip coating the steel sheet with a zinc-based coating, the steel sheet passing through a melt pool comprising aluminum between 0.5 and 4.0% by weight, magnesium between 0.5 and 4.0% by weight and the balance zinc and unavoidable impurities ; Removing the steel sheet coated with liquid melt from the melt bath and stripping off a part of the steel sheet still coated with liquid melt with a gaseous stripping medium in a stripping environment, the liquid melt remaining on the steel sheet completely solidifying after stripping and forming the coating on the steel sheet. Furthermore, the invention also relates to a hot-dip coated steel sheet. Such a Zn-Mg-Al coating is also referred to as a ZM coating.
  • These eutectic phases are made of the eutectic and pure metals, ie these eutectic phases have, in addition to the eutectic, secondary zinc grains and possibly aluminum phases (aluminum grains). These secondary zinc grains should not be confused with the primary zinc grains since they have a volume that is several orders of magnitude smaller than the primary zinc grains. While the primary zinc grains can have a diameter of up to 30 ⁇ m and even more, the diameter of the secondary zinc grains in the eutectic phases is up to 2 ⁇ m. Furthermore, these secondary phases are precipitated before or after the eutectic.
  • the eutectic phases described above are referred to as hypo- or hyper-eutectic phases, depending on whether they are precipitated before or after the eutectic.
  • the layer structure of a Zn-Mg-Al coating has an enrichment of eutectic phases that is not widespread but is distributed over the entire surface, which is above the zinc grains (and possibly also in the Zinc grains) are arranged.
  • the eutectic and the eutectic phases are essentially magnesium-rich phases, optionally aluminum-rich phases, in particular in the form of mixed crystals.
  • the enrichment of eutectic phases distributed over the entire area can be on average up to 100%, in particular up to 90%, for example up to 80%.
  • the addition of magnesium to the melt results in an improvement in corrosion resistance as well as reduced tool wear during forming.
  • the zinc-rich and the intermetallic MgZn2 phases are deposited from the melt in lamellar form, i.e. in alternating layers.
  • the aluminum-rich phase is also integrated into the lamellar layer structure.
  • the zinc phases contained in the eutectic are also referred to as secondary zinc grains.
  • the improved corrosion behavior is attributed to the microstructure of the eutectic phases in the coating.
  • dense eutectic structures consisting of zinc, zinc-magnesium (MgZn 2 ) and optionally aluminum phases are crucial so that the magnesium-rich phases that initially arise form an equally dense barrier layer and thus slow down the further corrosion process.
  • An increase in the surface area of the dense eutectic phases on the coating accordingly ensures an improvement in corrosion resistance.
  • the more efficient forming behavior of the Zn-Mg-Al coating is not yet fully understood, but it is assumed that it is based on the changed hardness properties of the phases that form on the coating surface.
  • the intermetallic zinc-magnesium (MgZn 2 ) phases in the eutectic are significantly harder and therefore more resistant to wear.
  • the aging of the Zn-Al-Mg coatings when stored in air or in an oxygen-containing atmosphere can result in a change in the chemical composition of the layers near the surface, and thus also lead to the formation and growth of oxides and oxide layers in and on the metallic coating.
  • the formation and growth of these oxides and oxide layers is associated with the penetration of oxygen into the eutectic phases of the protective layer and leads to additional deterioration in further processing.
  • elementary metal atoms from the eutectic and the eutectic phases are oxidized to form oxides and/or hydroxides or similar compounds (metal oxides).
  • phase rich in zinc and/or aluminum are hardly oxidized.
  • the metal oxides are in layers close to the surface, i.e. in the upper layers of the Coating arranged, in particular at a depth of approximately 0.01 and 0.1 ⁇ m. This layer is also known as the oxide layer.
  • the object of the invention is to provide a method for producing a hot-dip coated steel sheet, with which the proportion of eutectic phases in the layer of the coating near the surface can be increased, and to provide a corresponding hot-dip coated steel sheet.
  • the inventors have surprisingly discovered that if the previously known solidification mechanism is not given enough time and therefore the primary zinc crystals cannot grow quickly enough, no significant shift of the magnesium- and aluminum-rich phases as well as the eutectic phases can take place.
  • a correspondingly higher surface area share of eutectic phases can form in the layer near the surface and/or on the surface of the coating and thus also above the primary zinc grains within the coating (i.e. below the oxide layer on the surface of the coating) if the stripping medium is with a Temperature below 15 °C is supplied for stripping and / or a temperature below 15 °C is set in the stripping environment.
  • the higher surface area proportion of eutectic phases is present in comparison to a control that was produced analogously, but a stripping medium with a temperature above 15 ° C is supplied for stripping and / or there is a temperature above 15 ° C in the stripping environment.
  • the coating after the coating has solidified, there is a surface area of eutectic phases in the layer near the surface and/or on the surface of the coating and thus also above the primary zinc grains within the coating (i.e. below the oxide layer on the surface of the coating) of at least 65%, in particular at least 70%, 75% or 80%, preferably at least 85% or 90%, preferably at least 95%, 96%, 97%, 98%, 99% or more, up to 100%.
  • the method according to the invention reduces the thickness of the deposited lamellae, i.e. the phases in the lamellar layer structure of the eutectic, so that nanostructures are formed from zinc phases, preferably from the secondary zinc grains that are part of the eutectic and the other phases of the Eutectic, in particular the different mixed crystals form on the surface.
  • the secondary zinc grains which are formed close to the surface in the eutectic in the process according to the invention, have an average diameter of a maximum of 1 ⁇ m, preferably a maximum of 800 nm, 700 nm or 600 nm, particularly preferably a maximum of 500 nm, 400 nm or 300 nm, in particular a maximum of 250 nm and at least 1 nm, preferably at least 10 nm, 20 nm or 30 nm, particularly preferably at least 50 nm, 60 nm or 75 nm, in particular at most 100 nm.
  • a maximum of 1 ⁇ m preferably a maximum of 800 nm, 700 nm or 600 nm, particularly preferably a maximum of 500 nm, 400 nm or 300 nm, in particular a maximum of 250 nm and at least 1 nm, preferably at least 10 nm, 20 nm or 30 nm, particularly preferably at least 50 nm, 60 nm or
  • a layer close to the surface in the coating means a depth from the surface (including the oxide layer) up to at least 0.020 ⁇ m and in particular up to a maximum of 0.20 ⁇ m.
  • the temperature of the stripping medium and/or in the stripping atmosphere can in particular be below 10 °C, preferably below 5 °C, preferably below 0 °C.
  • the temperature can be limited to -50 °C, in particular to -40 °C, preferably to -30 °C.
  • the melt that is still in the liquid state applied to the steel sheet is stripped off, in that after leaving the melt pool, the steel sheet coated with liquid melt passes through a stripping device is passed through, which has means, for example nozzles, in particular slot nozzles, which act on both sides of the steel sheet with a gaseous stripping medium for stripping off the liquid melt.
  • a stripping environment In the area of impact or action of the gaseous stripping medium, a stripping environment is formed, which extends upwards and downwards in the direction of movement of the steel sheet and, depending on the intensity of the stripping (volume, speed, pressure, etc.), thus (passively) around the impact area of the gaseous stripping medium extends to the steel sheet coated with a molten coating.
  • this passive stripping environment can be described as a cuboid volume element.
  • the stripping can also take place in a so-called enclosure, so that the stripping environment can essentially be (actively) predetermined by the enclosure.
  • the stripping environment can therefore be passive or active, with the active version being adjustable in a more targeted manner, for example.
  • Suitable gaseous stripping mediums are (all) gases that are conventionally used in the stripping process, such as nitrogen, air, nitrogen-air mixture, etc., and can be cooled down to the desired temperature without changing their aggregate state and/or have a detrimental effect on the stripping process.
  • the gas can be treated accordingly, for example in a heat exchanger or through and/or in another device or process, before stripping and/or adjusting the temperature in the stripping environment, which occurs during use an enclosure would virtually correspond to flooding the enclosure.
  • the gas can be provided at the appropriate temperature or it can be cooled down to the desired temperature using suitable and common devices and methods.
  • Air, especially warm air, with any humidity is, for example, via an evaporator, e.g. B. a pipeline package with aluminum fins, guided and cooled, as a result of which the water vapor contained in the air condenses into water.
  • the thus cooled or cold air ( ⁇ 15 ° C) can be used according to the invention.
  • the purpose of stripping is to return excess melt on the steel sheet to the melt pool and to set a predetermined thickness of the coating (in the solid state). After setting the specified thickness and thus after stripping, the melt that is still in the liquid state on the steel sheet is then converted into a solidified state by (further) cooling.
  • Stripping devices and methods for stripping liquid melt on hot-dip coated steel sheets as well as supplying the gaseous stripping media for stripping and thus setting predetermined thicknesses of the coatings are state of the art.
  • the use of an enclosure surrounding the stripping device is also state of the art.
  • the contents of aluminum and magnesium can in particular be a maximum of 3.5% by weight, each preferably a maximum of 3.0% by weight, each preferably a maximum of 2.7% by weight and particularly preferably in each case be limited to a maximum of 2.5% by weight.
  • the aluminum with a content greater than 4.0% by weight in the coating can lead to a deterioration in desired processing properties, such as thermal joining.
  • a magnesium content greater than 4.0% by weight in the coating and therefore also in the melt does not lead to improved corrosion protection and can lead to increased slag formation in the coating process.
  • an increased use of aluminum and especially magnesium would significantly lower the solidus temperature of the eutectic, which could have a detrimental effect on the process control in the hot-dip coating system after stripping.
  • Elements such as bismuth, zirconium, nickel, chromium, lead, titanium, manganese, silicon, calcium, tin, lanthanum, cerium and iron can be present as impurities in the melt pool or in the coating in individual or cumulative amounts of up to 0.4% by weight be.
  • Sheet steel (substrate) is a flat steel product in strip form or sheet/plate form. It has a longitudinal extent (length), a transverse extent (width) and a height extent (thickness).
  • the steel sheet can be a hot strip (hot-rolled steel strip) or cold strip (cold-rolled steel strip), or can be made from a hot strip or a cold strip.
  • the flat steel product is preferably a cold strip.
  • the zinc-based coating has a thickness between 2 and 60 ⁇ m, in particular between 4 and 58 ⁇ m, preferably between 5 and 55 ⁇ m.
  • the thickness of the ZM coating can therefore be between at least 4 ⁇ m, preferably at least 5 ⁇ m and a maximum of 58 ⁇ m, preferably between 5 and a maximum of 55 ⁇ m, independently of each other on each side. This corresponds to the specified thickness, which can be specifically adjusted when stripping off the still liquid melt before solidification.
  • the hot-dip coated steel sheet is tempered.
  • a surface structure is impressed into the hot-dip coated steel sheet, which can be, for example, a deterministic surface structure.
  • Deterministic surface structure means, in particular, regularly recurring surface structures that have a defined shape and/or configuration or dimensioning. In particular, this also includes surface structures with a (quasi-) stochastic appearance, which are composed of stochastic form elements with a recurring structure. Alternatively, introducing a stochastic surface structure is also conceivable.
  • the hot-dip coated steel sheet can be straightened and/or stretch-straightened.
  • the hot-dip coated steel sheet is straightened and/or stretch-straightened after tempering.
  • the hot-dip coated steel sheet can be wetted with an aqueous cleaning solution.
  • An acidic or alkaline solution can be used as an aqueous cleaning solution.
  • the surface of the hot-dip coated steel sheet can be for a time of 1 to 60 s, in particular between 2 and 50 s, preferably between 3 and 40 s, preferably between 3 and 30 s, and at a temperature of 15 to 80 ° C, in particular from 20 to 80 ° C, preferably from 30 to 80 ° C, preferably from 40 to 80 ° C with an aqueous cleaning solution.
  • the wetting can be ended with an aqueous cleaning solution by rinsing with water and/or an aqueous solution.
  • the hot-dip coated steel sheet can be conditioned with an aqueous solution of an inorganic acid.
  • the aqueous solution of an inorganic acid has a pH value of less than 7, in particular less than 6, preferably less than 5, preferably less than 4.
  • the pH value can be at least 0.5, in particular at least 1.0, preferably at least 1.5.
  • An inorganic acid is selected from the group containing or consisting of: H 2 SO 4 , HCl, HNO 3 , H 3 PO 4 , H 2 SO 3 , HNO 2 , HF, or a mixture of 2 or more of these acids as an aqueous solution used.
  • the determination of the pH value is known.
  • the conditioning of the surface of the hot-dip coated steel sheet is to be designed three-dimensionally in the sense of the present invention. Either defined areas of the surface or the surface are completely wetted with an aqueous solution of an inorganic acid. Although two-dimensional areas are wetted, the wetting acts in layers of the coating close to the surface, i.e. in depth and thus in the third dimension.
  • the surface of the hot-dip coated steel sheet can be wetted with the aqueous solution of an inorganic acid for a time of 0.1 to 5 s and at a temperature of 10 ° C to 90 ° C.
  • the coating is preferably applied for a time of at least 0.1 s, in particular at least 0.2 s, preferably at least 0.3 s, 0.4 s, preferably at least 0.5 s, and a maximum of 5 s, in particular a maximum of 4 s wetted with an aqueous solution of an inorganic acid for a maximum of 3 s, 2 s, 1.8 s, preferably a maximum of 1.5 s, 1.2 s, 1.0 s.
  • the coating is wetted with an aqueous solution of an inorganic acid at a temperature of 10 °C to 90 °C, in particular 20 °C to 70 °C, preferably 20 °C to 50 °C, preferably 20 °C to 40 °C , particularly preferably 20 ° C to 30 ° C.
  • the wetting can be stopped by rinsing with water and/or an aqueous solution.
  • the wetting with an aqueous solution of an inorganic acid is interrupted by rinsing with water and/or an alcohol, for example selected from the group containing or consisting of methanol, ethanol, propanol, isopropanol, ethanol, in particular isopropanol, or an aqueous solution.
  • rinsing takes place in 2 steps, in a first step with water; in a second sub-step with an alcohol or an aqueous solution of an alcohol as stated above.
  • rinsing is carried out with water and an alcohol in one step, preferably as a mixture of water with one of the alcohols specified above.
  • the rinsing is preferably carried out continuously, and in particular a process selected from the group or consisting of spraying, spraying, dipping and application (coil coating process) can be used.
  • drying is preferably carried out by rinsing, with the “rinsed” coating preferably being dried by increasing the temperature (up to a maximum of 100 ° C) or by using a fan.
  • an aqueous activation solution can contain or consist of: at least one compound from the group oxalic acid, nickel phosphate, manganese phosphate, calcium phosphate, iron phosphate, aluminum phosphate, cobalt (II, III) phosphate, copper, copper sulfate, copper nitrate, copper chloride, copper carbonate, copper oxide, Silver, cobalt, nickel, Jernstedt salt, lead acetate, tin (tertra)chloride, arsenic oxide, zirconium chloride, zirconium sulfate, zirconium, iron, lithium, Zn 3 (PO 4 ) 2 , Zn 2 Fe(PO 4 ) 2 , Zn 2 Ni(PO 4 ) 2 , Zn 2 Mn(PO 4 ) 2 , Zn 2 Ca(PO 4 ) 2 .
  • the surface of the hot-dip coated steel sheet can be treated for a time of 1 to 60 s, in particular between 2 and 50 s, preferably between 3 and 40 s, preferably between 3 and 30 s, and at a temperature of 15 to 80 ° C, in particular from 20 to 80 ° C, preferably from 30 to 80 ° C, preferably from 40 to 80 ° C, with an aqueous activation solution.
  • activation can be dispensed with, whereby a step in the overall process can be saved and thus, according to a preferred embodiment, the surface of the hot-dip coated steel sheet is not wetted with an aqueous activation solution.
  • the hot-dip coated steel sheet can be wetted with an aqueous silane-based solution.
  • the aqueous silane-based solution may contain or consist of one or two or more compounds selected from the group (3,4-epoxyalkyl)trialkoxysilane, (3,4-epoxycycloalkyl)alkyltrialkoxysilane, 3-acryloxyalkyltrialkoxysilane, 3-glycidoxyalkyltrialkoxysilane, 3 -Methacryloxyalkyltrialkoxysilane, 3-(tri-alkoxysilyl)alkylsuccinic silane, 4-amino-dialkylalkyltrialkoxysilane, 4-amino-dialkylalkylalkyl-dialkoxysilane, aminoalkylaminoalkyltrialkoxysilane, aminoalkylaminoalkylalkyldialkoxysilane, amino-alkyltrialkoxysilane, amino
  • the surface of the hot-dip coated steel sheet can be for a time of 1 to 200 s, in particular between 2 and 150 s, preferably between 3 and 100 s, preferably between 3 and 40 s, and at a temperature of 15 to 40 ° C, in particular 20 up to 35 ° C, preferably from 25 to 30 ° C, with an aqueous solution based on silane.
  • the invention relates to a hot-dip coated steel sheet with a zinc-based coating which has aluminum between 0.5 and 4.0% by weight, magnesium between 0.5 and 4.0% by weight and the balance zinc and unavoidable impurities , wherein the coating contains zinc grains, magnesium-rich and/or aluminum-rich phases and eutectic phases, and a magnesium- and/or aluminum- and/or zinc-rich oxide layer is formed on the coating.
  • the eutectic phases are in the layer near the surface and/or on the surface of the coating and thus also above the primary zinc grains within the coating (i.e.
  • the secondary zinc grains which are arranged close to the surface in the eutectic, have an average diameter of a maximum of 1 ⁇ m, preferably a maximum of 800 nm, 700 nm or 600 nm, particularly preferably a maximum of 500 nm, 400 nm or 300 nm, in particular a maximum of 250 nm and at least 1 nm , preferably at least 10 nm, 20 nm or 30 nm, particularly preferably at least 50 nm, 60 nm or 75 nm, in particular at most 100 nm.
  • a nanostructure is arranged on the surface of the ZM coating, ie the ZM coating has a fissured surface, which is covered by the oxide layer and which the Nanostructure is essentially retained, since the oxide layer essentially follows the course of the nanostructure. Due to the high oxygen affinity of the magnesium in the ZM coating, a magnesium-rich oxide layer inevitably forms on the ZM coating, which can also contain aluminum-rich oxides. The oxide layer formed on the ZM coating can be between 5 and 50 nm or more. Due to solidification, the other phases of the eutectic, in particular the mixed crystal phases of the eutectic, are lower than the zinc phases, i.e. the secondary zinc grains. The nanostructure thus serves as an optimal starting point for anchoring at least one layer applied to the oxide layer.
  • nanoscale pretreatments will continue to increase and displace the previously common phosphating process in the post-treatment of hot-dip coated coatings.
  • Corresponding nanoscale pretreatments usually contain zirconium and/or organic silicon compounds and can be applied via spraying, dipping or coil coating processes.
  • the target layer thicknesses are between 5 to approx. 100 nm and are therefore smaller than zinc phosphate crystals in the range between 0.5 to 10 ⁇ m.
  • the temperature of the stripping medium and/or in the stripping atmosphere can in particular be below 10 °C, preferably below 5 °C, preferably below 0 °C.
  • the temperature can be limited to -50 °C, in particular to -40 °C, preferably to -30 °C.
  • the nanostructure can also be influenced by alloying aluminum in the melt or in the coating, whereby the maximum content must be limited to 4.0% by weight.
  • the at least one layer has an Si content of at least 1.0 mg/m2, in particular at least 2.5 mg/m2, preferably at least 5.0 mg/m2, preferably at least 7.5 mg/m2 and a maximum of 100.0 mg/m2 or 75.0 mg/m2, in particular a maximum of 50.0 mg/m2 or 40.0 mg/m2, preferably a maximum of 30.0 mg/m2 or 20.0 mg/m2 , preferably a maximum of 15.0 mg/m2 or 12.5 mg/m2.
  • XRF X-ray fluorescence analysis
  • GDOES Glow Discharge Optical Emission Spectroscopy
  • this contains or consists of at least one layer of organic silicon compounds, preferably one or more compounds selected from the group comprising or consisting of: silanes, silanols, siloxanes, alkoxysilanes, derivatives of silanes, siloxanes and/or alkoxysilanes as well as polymers and derivatives thereof.
  • Preferred derivatives are one or more compounds selected from the group comprising or consisting of: silanes, siloxanes, alkoxysilanes with functional groups such as -OR with R as H or alkyl, preferably C1 to C7, vinyl, phenyl, benzyl; -NR2 with R as H or alkyl, preferably C1 to C7, vinyl, phenyl, benzyl; Condensation products of hydrolyzed alkoxysilanes with elimination of water, i.e.
  • Alkoxysilanes have the general formula (RO)4-Si, R as alkyl, preferably C1 to C7.
  • the at least one layer has a Zr content of at least 1.0 mg/m2, in particular at least 2.5 mg/m2, preferably at least 5.0 mg/m2, preferably at least 7.5 mg/m2 and a maximum of 100.0 mg/m2 or 75.0 mg/m2, in particular a maximum of 50.0 mg/m2 or 40.0 mg/m2, preferably a maximum of 30.0 mg/m2 or 20.0 mg/m2, preferably a maximum of 15.0 mg/m2 or 12.5 mg/m2.
  • XRF X-ray fluorescence analysis
  • GDOES Glow Discharge Optical Emission Spectroscopy
  • this contains or consists of at least one layer of organic zirconium compounds, one or more compounds selected from the group ZrO2 and zirconate.
  • One embodiment relates to a hot-dip coated steel sheet, as described above, where the steel sheet is tempered.
  • One embodiment relates to a hot-dip coated steel sheet, as described above, with a temporary corrosion protection containing or consisting of a corrosion protection oil being applied to one layer.
  • Figure 3a is a schematic (not true to scale) reproduction of the facts as in Figure 1 and Figure 2 shown.
  • the oxide layer (3) is shown with the nanostructure (4) arranged underneath.
  • Figure 3b is a schematic (not to scale) enlargement of the area marked with the dash-dot line Figure 3a .
  • the nanostructure (4) can be seen with the fissured surface of the ZM coating, which is formed from the different height during the solidification of the secondary zinc grains (Zn-sec) and the further phases of the eutectic (E').
  • the nanostructure is covered by the oxide layer (3), the shape or the course of the surface of the nanostructure (4) being essentially maintained, since the oxide layer (3) essentially follows the course of the nanostructure (4).
  • the layer (5) of the nanoscale pretreatments containing zirconium and/or organic silicon compounds is shown.
  • hot-dipping processes used on an industrial scale can be simulated on a laboratory scale.
  • grade DC04 with a thickness of 0.7 mm was used as steel sheet, with 18 tests with different parameters, as shown in Table 1, being carried out.
  • Zn-Al-Mg coatings with different aluminum [in wt.%] and magnesium contents [in wt.%] were examined.
  • the stripping was carried out in an air atmosphere and a nitrogen-air mixture with a volume ratio of 30:70 was used as the gaseous stripping gas for stripping at different temperatures T [in °C].
  • the thickness of the coating in the solidified state was set at 12 ⁇ m.
  • the corresponding (new) surfaces of samples 1 to 18 with a new surface chemistry were subjected to a wetting test.
  • a static contact angle measurement was carried out.
  • the surface energy was measured using the contact angles of three different test liquids.
  • the results (average of 3 contact angle measurements per test liquid) were determined to be an average of 65° for samples 1 to 9 and an average of 75° for samples 10 to 18.
  • the area where the steel sheet emerges from the melt pool up to the stripping device can also be provided with an enclosure and flooded with a gas, as described above, in a stripping environment with a temperature below 15 ° C can.
EP23180236.4A 2022-06-23 2023-06-20 Procédé de fabrication d'une tôle d'acier revêtue par immersion à chaud et tôle d'acier revêtue par immersion à chaud Pending EP4296399A1 (fr)

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Citations (7)

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Publication number Priority date Publication date Assignee Title
US4552788A (en) * 1982-12-24 1985-11-12 Sumitomo Electric Industries, Ltd. Hot dipping method for forming a metal or alloy coating around an elongated body
EP2474649A1 (fr) 2011-01-05 2012-07-11 Voestalpine Stahl GmbH Procédé de traitement de surface d'un substrat ayant un revêtement de protection
US9481935B2 (en) * 2010-10-27 2016-11-01 Chemetall Gmbh Aqueous composition for pretreating a metal surface before applying another coating or for treating said surface
WO2019057635A1 (fr) * 2017-09-19 2019-03-28 Thyssenkrupp Steel Europe Ag Bande d'acier revêtue par immersion dans une masse fondue, présentant un aspect de surface amélioré et procédé pour sa fabrication
CN110983224A (zh) 2019-12-16 2020-04-10 首钢集团有限公司 一种热镀锌铝镁镀层钢及其制备方法
DE102019204224A1 (de) 2019-03-27 2020-10-01 Thyssenkrupp Steel Europe Ag Verfahren zur Neukonditionierung von feuerverzinkten Oberflächen
DE102020208991A1 (de) 2020-07-17 2022-01-20 Thyssenkrupp Steel Europe Ag Verfahren zur Herstellung eines schmelztauchbeschichteten Stahlblechs und schmelztauchbeschichtetes Stahlblech

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Publication number Priority date Publication date Assignee Title
US4552788A (en) * 1982-12-24 1985-11-12 Sumitomo Electric Industries, Ltd. Hot dipping method for forming a metal or alloy coating around an elongated body
US9481935B2 (en) * 2010-10-27 2016-11-01 Chemetall Gmbh Aqueous composition for pretreating a metal surface before applying another coating or for treating said surface
EP2474649A1 (fr) 2011-01-05 2012-07-11 Voestalpine Stahl GmbH Procédé de traitement de surface d'un substrat ayant un revêtement de protection
WO2019057635A1 (fr) * 2017-09-19 2019-03-28 Thyssenkrupp Steel Europe Ag Bande d'acier revêtue par immersion dans une masse fondue, présentant un aspect de surface amélioré et procédé pour sa fabrication
DE102019204224A1 (de) 2019-03-27 2020-10-01 Thyssenkrupp Steel Europe Ag Verfahren zur Neukonditionierung von feuerverzinkten Oberflächen
CN110983224A (zh) 2019-12-16 2020-04-10 首钢集团有限公司 一种热镀锌铝镁镀层钢及其制备方法
DE102020208991A1 (de) 2020-07-17 2022-01-20 Thyssenkrupp Steel Europe Ag Verfahren zur Herstellung eines schmelztauchbeschichteten Stahlblechs und schmelztauchbeschichtetes Stahlblech

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Title
LOSTAK THOMAS ET AL: "Organosilane modified Zr-based conversion layer on Zn-Al alloy coated steel sheets", SURFACE AND COATINGS TECHNOLOGY, ELSEVIER, NL, vol. 305, 15 August 2016 (2016-08-15), pages 223 - 230, XP029724314, ISSN: 0257-8972, DOI: 10.1016/J.SURFCOAT.2016.08.030 *

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