EP4538416A1 - Plattiertes stahlblech für heisspressformen mit hervorragender plattierungsqualität, stahlblech und herstellungsverfahren dafür - Google Patents

Plattiertes stahlblech für heisspressformen mit hervorragender plattierungsqualität, stahlblech und herstellungsverfahren dafür Download PDF

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Publication number
EP4538416A1
EP4538416A1 EP23820142.0A EP23820142A EP4538416A1 EP 4538416 A1 EP4538416 A1 EP 4538416A1 EP 23820142 A EP23820142 A EP 23820142A EP 4538416 A1 EP4538416 A1 EP 4538416A1
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EP
European Patent Office
Prior art keywords
steel sheet
plating
concentration
less
point
Prior art date
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Pending
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EP23820142.0A
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English (en)
French (fr)
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EP4538416A4 (de
Inventor
Sang-Heon Kim
Jin-Ho Jung
Won-Hwi LEE
Seong-Choon KWON
Ki-Cheol KANG
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Posco Holdings Inc
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Posco Co Ltd
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Application filed by Posco Co Ltd filed Critical Posco Co Ltd
Publication of EP4538416A1 publication Critical patent/EP4538416A1/de
Publication of EP4538416A4 publication Critical patent/EP4538416A4/de
Pending legal-status Critical Current

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    • 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
    • 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
    • C25D3/20—Electroplating: Baths therefor from solutions of iron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
    • C23C2/0222—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating in a reactive atmosphere, e.g. oxidising 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
    • C23C2/04—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
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    • 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
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    • 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
    • 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
    • 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
    • C23C28/023—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
    • 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
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
    • C23C28/3225—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only with at least one zinc-based 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
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D21/00—Processes for servicing or operating cells for electrolytic coating
    • C25D21/02—Heating or cooling
    • 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
    • C25D9/00—Electrolytic coating other than with metals
    • C25D9/04—Electrolytic coating other than with metals with inorganic materials
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    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D9/00—Electrolytic coating other than with metals
    • C25D9/04—Electrolytic coating other than with metals with inorganic materials
    • C25D9/06—Electrolytic coating other than with metals with inorganic materials by anodic processes

Definitions

  • the present disclosure relates to a plated steel sheet for hot press forming having excellent plating quality, a steel sheet for plating, and a manufacturing method therefor.
  • Hot press forming is a processing method for obtaining high-strength parts by forming and cooling a steel sheet at high temperatures substantially simultaneously.
  • the steel sheet used for hot press forming should have excellent hardenability so that martensite may be easily formed when cooled at high temperature.
  • various alloying elements are added to steel for hot press forming compared to general steel, and in particular, many elements with a high oxidation tendency compared to Fe, such as Mn, Si, Al, Cr, and B, are added.
  • various types of plating are applied to a surface of the steel sheet. Thereamong, methods of plating the surface of the steel sheet by hot-dip plating, such as hot-dip galvanizing or hot-dip aluminum plating, are widely used.
  • plating quality is determined by a surface condition of an annealed steel sheet immediately before plating, and plating properties may deteriorate due to the formation of surface oxides during annealing caused by elements such as Mn, Si, Al, Cr, and B added to secure physical properties of the steel sheet. That is, during the annealing process, the elements may diffuse to surfaces thereof and react with a trace amount of oxygen or water vapor present in an annealing furnace to form single or complex oxides of the elements on the surface of the steel sheet, thereby reducing reactivity of the surface.
  • elements such as Mn, Si, Al, Cr, and B added to secure physical properties of the steel sheet. That is, during the annealing process, the elements may diffuse to surfaces thereof and react with a trace amount of oxygen or water vapor present in an annealing furnace to form single or complex oxides of the elements on the surface of the steel sheet, thereby reducing reactivity of the surface.
  • the surface of the annealed steel sheet with the reduced reactivity interferes with wettability of a hot-dip plating bath, causing non-plating in which a plating metal is not attached locally or entirely to the surface of the plated steel sheet.
  • these oxides significantly deteriorate the plating quality of plated steel sheets, such as peeling of a plating layer due to the insufficient formation of an alloying inhibition layer (Fe 2 Al 5 ) required to secure adhesion of the plating layer during a hot-dip plating process.
  • Patent Document 1 discloses a technology providing a hot-dip galvanized steel sheet or a galvannealed steel sheet having excellent plating quality, by controlling an air-fuel ratio of air and fuel to 0.08 to 0.95, during the annealing process, oxidizing the steel sheet in a direct flame furnace in an oxidizing atmosphere to form an iron oxide including Si, Mn or Al alone or complex oxides to a certain depth inside the steel sheet, and then reducing and annealing the iron oxide in a reducing atmosphere and then performing hot-dip galvanizing.
  • Si is concentrated directly below the iron oxide during the reduction process, thereby forming a band-shaped Si oxide, so that peeling occurs in a surface layer portion including a plating layer, that is, peeling occurs at an interface between the reduced iron and a base steel sheet therebelow, causing a problem in that it is difficult to secure adhesion of the plating layer.
  • An object of the present disclosure is not limited to the above description.
  • the object of the present disclosure will be understood from the entirety of the contents of the present specification, and a person skilled in the art to which the present disclosure pertains will understand an additional object of the present disclosure without difficulty.
  • a steel sheet for hot press forming including, by weight%: 0.1 to 4% of Mn, 0.001 to 2% of Si, 0.02 to 0.6% of C, 0.001 to 1% of Al, 0.05% or less of P, 0.02% or less of S, 1% or less of Cr, 0.01% or less of B, with a balance of Fe and inevitable impurities, wherein each of a GDS profile of an Mn element and a GDS profile of an Si element, observed from a surface thereof in a depth direction, sequentially includes a maximum point and a minimum point, a difference between a value obtained by dividing a Mn concentration at the maximum point in the GDS profile of the Mn element by a Mn concentration of a base material, and a value obtained by dividing a Mn concentration at the minimum point in the GDS profile of the Mn element by the Mn concentration of the base material (a difference of converted concentration of Mn) may be 10% or
  • a point at a depth of 5 ⁇ m is considered to be a point at which the minimum point appears.
  • a hot-dip plated steel sheet for hot press forming may include the steel sheet for plating described above and a hot-dip plated layer formed on the steel sheet for plating.
  • a method for manufacturing a steel sheet for hot press forming including: preparing a base steel sheet including, by weight%: 0.1 to 4% of Mn, 0.001 to 2% of Si, 0.02 to 0.6% of C, 0.001 to 1% of Al, 0.05% or less of P, 0.02% or less of S, 1% or less of Cr, 0.01% or less of B, with a balance of Fe and inevitable impurities, performing electroplating on the base steel sheet to form an Fe plating layer including 5 to 50 wt% of oxygen; and annealing the base steel sheet on which the Fe plating layer is formed by maintaining at a temperature range of 600 to 950°C for 5 to 120 minutes in an annealing furnace with 1 to 70% H 2 -remaining N 2 gas atmosphere, controlled at a dew point lower than -20°C.
  • a method for manufacturing a hot-dip plated steel sheet for hot press forming including: preparing a base steel sheet including, by weight%: 0.1 to 4% of Mn, 0.001 to 2% of Si, 0.02 to 0.6% of C, 0.001 to 1% of Al, 0.05% or less of P, 0.02% or less of S, 1% or less of Cr, 0.01% or less of B, with a balance of Fe and inevitable impurities, performing electroplating on the base steel sheet to form an Fe plating layer including 5 to 50 wt% of oxygen; obtaining a steel sheet for plating by annealing the base steel on which the Fe plating layer is formed by maintaining at a temperature range of 600 to 950°C for 5 to 120 seconds in an annealing furnace with 1 to 70% H 2 -remaining N 2 gas atmosphere, controlled at a dew point temperature of lower than -20°C; and dipping the steel sheet for plating in a hot-dip plating bath
  • a hot-dip plated steel sheet in which a phenomenon in which non-plating occurs during hot-dip plating is significantly improved and plating adhesion is improved by forming a pre-plating layer and controlling concentration profiles of Mn and Si elements therein, may be provided.
  • FIG. 1 is a schematic diagram of a GDS profile of Mn and Si elements measured after removing a plating layer of a hot-dip plated steel sheet manufactured of a cold-rolled steel sheet electroplated with Fe.
  • FIG. 2 is a schematic diagram of a process in which a base steel sheet having an Fe plating layer containing oxygen formed thereon is annealed.
  • an Fe electroplating amount is a plating amount measured as a total amount of Fe included in a plating layer per unit area, and oxygen and inevitable impurities in the plating layer were not included in the plating amount.
  • a concentration and concentration profile referred to in the present disclosure mean a concentration and concentration profile measured using GDS, i.e., a glow discharge optical emission spectrometer.
  • an oxidation-reduction method As a method of forming an oxide layer containing a large amount of oxygen to suppress the diffusion of alloying elements such as Mn, Si, and the like to the surface, an oxidation-reduction method, the method in which an oxide layer is oxidized during a temperature increase and then reduced again by maintaining the oxide layer in a reducing atmosphere, or a method in which an iron oxide is coated on a surface of a base steel sheet and heat treated, may be used.
  • the iron oxide firmly formed on the surface of the base steel sheet is a mixture of FeO, Fe 3 O 4 , and Fe 2 O 3 , which are difficult to reduce, and while the surface is reduced to metallic steel during the annealing process in a reducing atmosphere, an interface between the iron oxide layer and the base steel sheet has a slow reduction rate, making it difficult to completely reduce, and Mn and Si oxides accumulate at the interface to form a continuous oxide layer. Therefore, although wettability with molten zinc may be improved, the oxide layer may easily crumble, causing a problem in which the plating layer is peeled off.
  • a thin oxide film is formed on the surface of the base steel sheet, and if a surface of a cold-rolled steel sheet is not completely homogeneous before annealing, or if there is a local deviation in oxygen partial pressure, temperature, or the like, the wettability is uneven during hot-dip galvanizing, causing non-plating, or if the thickness of the oxide film is uneven during an alloying heat treatment process after galvanizing, causing a difference in a degree of alloying, there is a tendency for linear defects that can be easily identified with the naked eye to occur.
  • the present inventors have attempted to manufacture a hot-dip plated steel sheet having an attractive surface and no plating peeling problem by controlling the presence of Mn and Si, which are oxidizing elements, on the surface of the steel sheet for plating as follows.
  • the steel sheet according to an embodiment of the present disclosure may have the following characteristics in terms of the GDS concentration profile of Mn and Si.
  • a steel sheet for plating of the present disclosure will be described in detail with reference to the GDS profile of FIG. 1 .
  • FIG. 1 is a graph schematically illustrating a typical GDS profile of an alloy element that may appear from a surface portion after a galvanized layer is removed from a hot-dip plated steel sheet including the steel sheet of the present disclosure.
  • a vertical axis represents a concentration of alloying elements such as Mn, Si, and the like
  • a horizontal axis represents a depth.
  • the steel sheet of the present disclosure may have a very low concentration of Mn on the surface, and may have a concentration gradient in the form of maximum and minimum points appearing sequentially from the surface in a depth direction.
  • sequentially having the maximum and minimum points does not necessarily mean that the maximum point appears first in the depth direction from the surface (interface), and in some cases, means that the minimum point may appear first, but the maximum point and the minimum point should appear sequentially thereafter.
  • the minimum point may not appear, and in this case, the internal concentration in the 5 ⁇ m depth region may be a concentration of the minimum point.
  • the concentration of alloying elements on the surface may have a lower value than the concentration at the maximum point, but in some cases, a minimum point with a low concentration of alloying elements may appear between the surface and the maximum point.
  • the surface layer portion corresponds to an Fe plating layer with a low concentration of alloying elements since the alloying elements are not greatly diffused from a base steel sheet
  • the maximum point corresponds to a region in which internal oxides of the alloying elements formed near an interface between the Fe plating layer and base steel sheet are concentrated
  • the minimum point appearing on a side of the base steel sheet in the Fe plating layer corresponds to a region in which alloying elements diffuse to the Fe plating layer not including the alloying elements and are diluted, or a region in which alloying elements diffuse to the maximum point at which internal oxidation occurs and are depleted.
  • the maximum point may be formed at a depth of 0.05 to 1.0 ⁇ m from a surface of the steel sheet. If the maximum point appears in a region deeper than the region described above, it may not be determined to be a maximum point due to the effect of the present disclosure.
  • the minimum point can be formed at a location within 5 ⁇ m of depth of the surface of the steel sheet. As described above, if the minimum point is not formed at the point within 5 ⁇ m of depth, the 5 ⁇ m of depth may be determined to be a point at which the minimum point is formed. Since the concentration at the depth of 5 ⁇ m is substantially the same as the concentration of a base material, it can be considered to be a point at which the concentration no longer decreases.
  • the converted concentration value at the maximum point of Mn and Si - the converted concentration value at the minimum point Mn and Si may respectively be 10% or more.
  • the difference of converted concentration values may be set to 200% or less for both Mn and Si. In another embodiment of the present disclosure, the difference of converted concentration of Mn and Si may be 15% or more or 20% or more.
  • an acid solution was removed within 10 seconds when bubble generation due to a reaction between the plating layer and the acid solution is stopped, and the base steel sheet was washed using pure water and dried. If it is a steel sheet for plating that has not yet been hot-dip plated, it may be analyzed without removing the plating layer.
  • the GDS concentration profile measures concentrations of all elements contained in the steel sheet at intervals of 1 to 5 nm in a thickness direction of the steel sheet. Irregular noise may be included in the measured GDS profile, an average concentration profile was obtained by applying a Gaussian filter with a cutoff value of 100 nm to the measured concentration profile to obtain the maximum and minimum points of the Mn and Si concentrations, and the concentration values and depths at the maximum and minimum points of the concentrations were respectively obtained from the noise-removed profile.
  • the maximum and minimum points mentioned in the present disclosure were calculated as maximum and minimum points only when the difference between the maximum point and the minimum point in the depth direction was 10 nm or more.
  • the steel sheet for plating targeted in the present disclosure may include a base steel sheet and an Fe plating layer formed on the base steel sheet.
  • the composition of the base steel sheet is not particularly limited.
  • the steel sheet is a steel sheet having a composition which easily forms oxides on the surface, containing 0.1 to 4 wt% of Mn and 0.001 to 2 wt% of Si
  • plating properties may be advantageously improved by the present disclosure.
  • An upper limit of a concentration of Mn of the base steel sheet is not particularly limited, but considering the composition commonly used, the upper limit may be limited to 4 wt%.
  • a lower limit of the concentration of Mn is not particularly limited, if a composition contains less than 0.1 wt% of Mn, the surface quality of a hot-dip plated steel sheet is attractive, even if a Fe plating layer is not formed, so there is no need to perform Fe electroplating thereon.
  • Mn and Si are elements affecting the plating property, the concentrations of Mn and Si may be limited as described above, but in the present disclosure, the remaining elements of the base steel sheet are not particularly limited.
  • the base steel sheet may include, by weight%: 0.1 to 4% of Mn, 0.001 to 2% of S, 0.02 to 0.6% of C, 0.001 to 1% of Al, 0.05% or less of P, 0.02% or less of S, 1% or less of Cr, 0.01% or less of B, with a balance of Fe and inevitable impurities.
  • P, S are impurities, which are advantageous when not added, and Cr and B are optional elements and do not need to be added, so lower limits thereof are not set.
  • a hot-dip plated steel sheet including the steel sheet for plating may be provided, and the hot-dip plated steel sheet may include a steel sheet for plating and a hot-dip plated layer formed on a surface of the steel sheet for plating.
  • any commercially available hot-dip plated steel sheet can be used, and there are no specific restrictions on the type thereof.
  • the steel sheet for plating may be manufactured by a process including: preparing a base steel sheet; performing electroplating on the base steel sheet to form an Fe plating layer including 5 to 50 wt% of oxygen; and annealing the base steel sheet on which the Fe plating layer is formed.
  • the electroplated cold-rolled steel sheet was annealed in an atmosphere of N 2 -5% H 2 , a dew point of -40°C, and a temperature of 800°C for 53 seconds, and then cooled.
  • This phenomenon is because an Fe plating layer with a high oxygen content was formed before annealing. That is, when the iron electroplating layer contains 5 to 50 wt% of oxygen, and when annealed in an annealing furnace in a reducing atmosphere, oxygen in the iron electroplating layer oxidizes alloying elements such as Mn, Si, and the like, diffusing from the base steel sheet to the surface and is accumulated at the interface between the iron electroplating layer and the base steel sheet. Therefore, as illustrated in the graph of FIG. 1 , when the concentration is measured with GDS, a maximum point with high concentrations of Mn, Si, and the like, is confirmed at a depth corresponding to the thickness of the iron electroplating layer from the surface.
  • an alloying element having a slow diffusion rate such as Mn, or the like, cannot diffuse quickly from the base steel sheet even when the concentration thereof is diluted by the iron electroplating layer or the dissolved Mn is depleted due to internal oxidation, so a minimum point may exist after the maximum point obtained by the measured GDS concentration.
  • Si rapidly diffuses from the inside during the annealing process, and internal oxidation is continuously performed at the interface between the iron electroplating layer and the base steel sheet, oxides are accumulated, a minimum point may not be confirmed in the GDS concentration analysis. Therefore, the fact that the minimum point does not appear in the GDS concentration profile means that the alloying elements such as Mn, Si, and the like, were oxidized by the iron electroplating layer and effectively suppressed from the diffusion to the surface.
  • the uniformly formed iron electroplating layer may suppress the formation of surface oxides and reduce the concentration of alloying elements such as Mn, Si, and the like, dissolved on the surface of the steel sheet, thereby promoting an alloying reaction with the galvanized layer, thereby obtaining a uniformly hot-dip alloy-plated steel sheet without surface defects.
  • an iron electroplating layer containing 5 to 50 wt% of oxygen is formed on the base steel sheet to have an iron adhesion amount of 0.5 to 3.0g/m 2 , the temperature is increased to 600 to 950°C so that the mechanical properties of the steel sheet may be secured, and then cooled to perform hot-dip plating.
  • the Fe plating layer may be formed through a continuous plating process, and the Fe plating amount herein may be 0.5 to 3.0 g/m 2 based on the Fe adhesion amount. If the Fe plating amount is less than 0.5 g/m 2 , a diffusion suppression effect of alloying elements by the Fe plating layer may be insufficient in a common continuous annealing process.
  • the Fe plating amount may be 1.0 to 2.0 g/m 2 .
  • the Fe plating amount of 0.5 to 3.0 g/m 2 of the present disclosure may correspond to a thickness of 0.05 to 0.4 ⁇ m after annealing.
  • the Fe plating layer having the above-described high oxygen concentration may have maximum and minimum points in the GDS concentration profile of Mn and Si elements formed inside the steel sheet for plating by controlling the temperature, dew point temperature, and atmosphere in a subsequent annealing process, and is configured so that the converted concentration at the maximum point and the converted concentration at the minimum point may satisfy a numerical range limited in an embodiment of the present disclosure.
  • the concentration of oxygen in the Fe plating layer may be 5 to 50 wt%, and in another embodiment, the concentration of oxygen in the Fe plating layer may be 10 to 40 wt%. In order to obtain the surface oxide suppression effect, the amount of oxygen in the Fe plating layer should be sufficient.
  • the surface oxide suppression effect may be obtained by increasing the Fe plating amount, but in order to obtain such an effect, plating should be performed in excess of 3.0 g/m 2 , which may cause various problems as described above.
  • the content of oxygen in the Fe plating layer is controlled to be 5 wt% or more.
  • the surface oxide suppression effect during annealing can be further increased as the concentration of oxygen in the Fe plating layer increases, but since it is difficult to obtain a plating layer in excess of 50 wt% using a common electroplating method, an upper limit thereof may be limited to 50 wt%. In another embodiment of the present disclosure, the concentration of oxygen in the Fe plating layer may be limited to 10 to 40%.
  • an annealing temperature may be 600°C to 950°C based on a temperature of the steel sheet in a soaking section. If the annealing temperature is too low, since a structure of the cold-rolled steel sheet is not properly be recovered or not recrystallized, so it is difficult to secure mechanical properties such as strength, elongation, and the like, of the steel sheet, and if the annealing temperature is higher than 950°C, alloying elements in the steel rapidly diffuse to the surface, resulting in poor quality of hot-dip plating, and the operation is performed unnecessarily at high temperatures, which may be uneconomical.
  • a dew point temperature inside the annealing furnace is not necessarily limited thereto, but may be lower than -20°C.
  • the dew point temperature is maintained below -20°C, since a separate humidifying device is not required to increase the dew point, which may be economical.
  • an Fe plating layer having a high oxygen concentration is formed, even if internal oxidation by the atmosphere is not necessarily induced, it is possible to sufficiently prevent alloying elements such as Mn, Si, and the like from diffusing to the surface.
  • a lower limit of the dew point temperature is not specifically set.
  • the dew point herein may be -70 to - 30°C.
  • a concentration of hydrogen in the atmosphere gas during annealing may be set to 1% or more by volume%.
  • the hydrogen concentration is less than 1%, a trace amount of oxygen inevitably included in H 2 and N 2 gases cannot be effectively oxidized and removed, which increases the oxygen partial pressure and can cause surface oxidation of the base steel sheet.
  • the hydrogen concentration exceeds 70%, there may be a risk of explosion in the event of gas leakage and the cost of high-hydrogen work increases, so the hydrogen concentration may be set to 70% or less. Except for the impurity gases which are inevitably included other than the hydrogen (H 2 ), it may be substantially nitrogen (N 2 ).
  • a holding time after reaching a target temperature during annealing may be limited to 5 to 120 seconds.
  • the holding time is required to be maintained at the target temperature during annealing for 5 seconds or longer.
  • the holding time during annealing at high temperatures becomes excessively long, the diffusion of alloying interfering elements through the Fe plating layer increases, which increases the amount of surface oxides generated, and as a result, the quality of hot-dip plating deteriorates, so the holding time may be limited to 120 seconds or less.
  • FIG. 2 schematically illustrates a phenomenon which occurs inside a steel sheet as a temperature of the steel sheet increases according to the conditions of the present disclosure.
  • FIG. 2 (a) illustrates a schematic cross-sectional diagram of a base steel sheet on which an Fe plating layer containing a large amount of oxygen is formed.
  • the base steel sheet includes alloying elements such as Mn, Si, and the like, and the Fe plating layer includes 5 to 50 wt% of oxygen and impurities which are inevitably incorporated during plating, and the remainder is comprised of Fe.
  • FIG. 2 (b) illustrates a state in which a cold-rolled steel sheet, electroplated with Fe, is heated to about 300 to 500°C in a nitrogen atmosphere containing 1 to 70% H 2 .
  • a surface of the Fe plating layer containing a large amount of oxygen is gradually reduced and the oxygen is removed, and internal oxides of elements such as Mn, Si, and the like, diffused from the base steel sheet begin to be generated at an interface between the Fe plating layer and the base steel sheet, and as the temperature increases the oxides at grain boundaries grow coarsely.
  • FIG. 2 (c) illustrates a schematic cross-sectional view of a base steel sheet when the temperature is increased from 500 to 700°C in the same reducing atmosphere.
  • the Fe plating layer is almost completely reduced, thereby forming ferrite with lower Mn and Si concentrations compared to that of the base steel sheet, and as oxygen in the Fe plating layer is gradually depleted, Mn and Si begin to penetrate the Fe plating layer and slowly diffuse to the surface of the Fe plating layer.
  • FIG. 2 (d) illustrates a cross-sectional schematic diagram of a steel sheet that has been annealed at a temperature within a range of 600 to 950°C. Except for internal oxides of elements such as Mn, Si, and the like, in the iron electroplating layer, oxygen dissolved in metallic steel is completely removed, and the generated internal oxides generated are generally spherical or short plate-shaped. In addition, due to grain growth, the iron electroplating layer may form single grains with the base steel sheet.
  • the form of the internal oxides is not necessarily generated in the form of particles, and depending on elongation of the cold-rolled steel sheet, the composition of steel, the atmosphere in the annealing furnace, and the content of oxygen contained in the iron electroplating layer, the grains of the base steel sheet and the iron electroplating layer may appear to be distinct, or short linear oxides may be formed along the interface between the iron electroplating layer and the base steel sheet or grain boundaries within the base steel sheet.
  • the annealed steel sheet may be cooled. Since the cooling conditions in the cooling operation after the annealing operation do not significantly affect the surface quality of a final product, that is, the plating quality, there is no need to specifically limit the cooling conditions in the present disclosure. However, in order to prevent oxidation of iron elements during the cooling process, an atmosphere which is at least reducing for iron may be applied.
  • a hot-dip plated layer may be formed by hot-dip plating the steel sheet for plating obtained by the above-described process.
  • the hot-dip plating method in the present disclosure is not particularly limited.
  • the type of plating of the present disclosure is not particularly limited as long as it is a plating method used for a steel sheet for hot press forming, and some non-limiting examples thereof may include hot-dip galvanizing, hot-dip aluminum plating, or the like. It should be noted that it is not necessary to use pure zinc or aluminum in hot-dip galvanizing or hot-dip aluminum plating and alloy plating including magnesium, aluminum, zine, or alloying elements included in other plating layers may also be sufficiently used.
  • any base steel sheet having the alloy composition described above may be applied without limitation as the base steel sheet of the steel sheet for plating or hot-dip plated steel sheet according to the present disclosure, the method of manufacturing the base steel sheet may not be specifically limited.
  • an Fe plating layer can be formed on a surface of a base steel through an electroplating method, and an oxygen concentration of the formed Fe plating layer may be controlled by appropriately controlling the conditions of the electroplating solution and the plating conditions.
  • an electroplating solution in order to form an Fe plating layer, an electroplating solution may be used, the electroplating solution including: iron ions including ferrous ions and ferric ions; a complexing agent; and inevitable impurities, wherein a concentration of the ferric ions of the iron ions is 5 to 60% by weight.
  • the electroplating solution includes ferrous ions and ferric ions.
  • the electroplating solution includes only ferrous ions.
  • the electroplating solution may further include the ferric ions.
  • the concentration of the ferric ions is preferably 5 to 60 wt%, and is more preferably 5 to 40 wt% of the total sum of ferrous and ferric ions.
  • the concentration is less than 5%, a rate at which ferric iron is reduced to ferrous iron at a cathode is less than a rate at which ferrous iron is oxidized to ferric iron at an anode, so the concentration of ferric iron rises rapidly, and pH drops rapidly and plating efficiency continues to deteriorate.
  • the concentration of ferric ions exceeds 60%, a reaction amount in which ferric iron is reduced to ferrous iron at the cathode is greatly increased, compared to a reaction amount in which ferrous iron is reduced and precipitated as metallic steel, so the plating efficiency decreases significantly and the plating quality deteriorates.
  • the concentration of ferric ions among the iron ions is 5 to 60 wt%.
  • the concentration of iron ions is preferably 1 to 80 g per 1 L of the electroplating solution, and is more preferably 10 to 50 g per 1 L.
  • concentration of iron ions is less than 1g/L, there is a problem that the plating efficiency and plating quality deteriorate rapidly.
  • concentration of iron ions exceeds 80g/L, solubility may be exceeded and precipitation may occur, and loss of a raw material due to loss of the solution in the continuous plating process increases, which may be uneconomical.
  • the electroplating solution of the present disclosure includes a complexing agent, and in order to maintain high plating efficiency without generating sludge while containing a large amount of ferric iron, it is preferable to use an amino acid or an amino acid polymer as a complexing agent.
  • amino acid refers to an organic molecule in which a carboxyl group (-COOH) and an amine group (-NH 2 ) are combined
  • amino acid polymer refers to an organic molecule formed by polymerizing two or more amino acids, and an amino acid polymer has properties of complexing agents, similar to that of an amino acid. Therefore, in the following description, an amino acid and an amino acid polymer are collectively referred to as an amino acid.
  • an amino acid When an amino acid is dissolved in neutral water, since amine combines with hydrogen ions to acquire a positive charge, and a carboxyl group dissociates the hydrogen ion to acquire a negative charge, the amino acid molecule maintains a neutral charge. Meanwhile, when the solution becomes acidic, since the carboxyl group recombines with the hydrogen ions, making the charge neutral, and amine has a positive charge, the amino acid molecule forms a cation. In other words, an amino acid forms a neutral charge or cation in a slightly acidic aqueous solution.
  • the amino acid When an amino acid is added to an acidic electrolyte containing iron ions, the amino acid is complexed with ferrous and ferric ions, and the iron ions complexed with the amino acid maintain a cationic state even in the complexed state. Therefore, it exhibits electrically opposite properties to the common complexing agent having a plurality of carboxyl groups, having a negative charge in a weakly acidic aqueous solution.
  • an amino acid forms fewer bonds with iron ions and has a weaker bonding force, but the bonding force with ferric ions which generates sludge is sufficiently strong, so precipitation due to ferric ions may be prevented.
  • the ferric ions may maintain cations even when the ferric ions are complexed, the ferric ions can be easily transferred to a cathode and reduced to ferrous ions to participate in a plating reaction, while the movement thereof to an anode is suppressed, so a production rate of the ferric ions is slowed down, so that the concentration of ferric ions is maintained at a constant level even when continuous plating is performed for a long period time, the plating efficiency is maintained constant, and there is no need to replace an electrolyte.
  • an amino acid as a complexing agent, sludge may be prevented, and not only ferrous ions but also ferric ions may be used as a plating material, and when ferrous ions and ferric ions are mixed and used, the change in pH of the solution may be slowed down, and the accumulation of ferric ions may be easily prevented, so that the electroplating efficiency and plating quality may be maintained to be constant in a continuous electroplating process.
  • the complexing agent is preferably added in an amount so that a molar concentration ratio between the iron ion and the complexing agent is 1:0.05 to 2.0, and more preferably 1:0.5 to 1.0.
  • a molar concentration ratio is less than 0.05, the ferric ions excessively contained, cannot be suppressed from combining with hydroxide ions or oxygen to form sludge, and even when ferric ions are not included, the plating efficiency is greatly reduced, and furthermore, burning is induced, resulting in poor plating quality.
  • the complexing agent is preferably at least one selected from amino acids or amino acid polymers.
  • the complexing agent may be at least one selected from alanine, glycine, serine, threonine, arginine, glutamine, glutamic acid, and glycylglycine.
  • an Fe plating layer having high plating efficiency and high oxygen concentration may be obtained.
  • the electroplating efficiency decreases, which is not suitable for a continuous plating process. If the pH of the Fe electroplating solution exceeds 5.0, the plating efficiency increases, but sludge in which iron hydroxide precipitates is generated during continuous electroplating, causing problems such as pipe clogging and contamination of rolls and equipment.
  • the current density is less than 3A/dm 2 , a plating overvoltage of the cathode decreases and the Fe electroplating efficiency decreases, so it is not suitable for a continuous plating process. If the current density exceeds 120A/dm 2 , burning occurs on the plating surface, causing the electroplating layer to become uneven and the Fe plating layer to easily fall off.
  • an anionic complexing agent such as acetic acid, lactic acid, citric acid, or EDTA
  • the iron ions combined with OH - ions in the complexing agent have an average negative charge, and when a cathode is applied for electroplating, repulsion electrically occurs, which suppresses the incorporation into the Fe plating layer.
  • amino acids are electrically neutral at pH 2.0 to 5.0, and have cations in strong acids below pH 2.0. Even if 1 to 2 OH - s are combined to the iron ion combined with the amino acid, the amino acids have cations, so electrical attraction with the cathode performing electroplating occurs, causing a large amount of oxygen to be incorporated therein.
  • an amino acid is used as a complexing agent so that a molar concentration ratio between iron ions and amino acids is 1: 0.05 to 1:2.0, and Fe electroplating is performed while maintaining pH at 2.0 to 5.0, an Fe plating layer containing 5 to 50 wt% oxygen can be obtained while having high plating efficiency and suppressing sludge generation.
  • the Fe electroplating amount is less than 0.5g/m 2 , since oxygen contained in the Fe plating layer is quickly reduced and removed, Mn and Si diffuse from the base steel sheet so that the formation of surface oxides may not be effectively suppressed, so that there is a problem in that the quality of hot-dip plating deteriorates.
  • the Fe plating amount is an iron concentration contained in the plating layer, and when the Fe plating layer is completely reduced during annealing, it has a thickness of about 0.05 to 0.4 ⁇ m.

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CN118932270B (zh) * 2024-05-27 2026-02-10 华菱安赛乐米塔尔汽车板有限公司 镀铝硅钢及制备方法、预涂镀钢、热成型构件的生产工艺

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