EP4314374A1 - Tôle d'acier galvanisée par immersion à chaud - Google Patents

Tôle d'acier galvanisée par immersion à chaud

Info

Publication number
EP4314374A1
EP4314374A1 EP22717072.7A EP22717072A EP4314374A1 EP 4314374 A1 EP4314374 A1 EP 4314374A1 EP 22717072 A EP22717072 A EP 22717072A EP 4314374 A1 EP4314374 A1 EP 4314374A1
Authority
EP
European Patent Office
Prior art keywords
coating
steel sheet
magnesium
zinc
oxide layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22717072.7A
Other languages
German (de)
English (en)
Inventor
Burak William Cetinkaya
Fabian JUNGE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ThyssenKrupp Steel Europe AG
Original Assignee
ThyssenKrupp Steel Europe AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by ThyssenKrupp Steel Europe AG filed Critical ThyssenKrupp Steel Europe AG
Publication of EP4314374A1 publication Critical patent/EP4314374A1/fr
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—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
    • 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
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/34—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
    • C23C22/12—Orthophosphates containing zinc 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
    • 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
    • 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
    • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process

Definitions

  • the invention relates to a hot-dip coated steel sheet with a Zn-Mg-Al coating.
  • these eutectic phases also have (secondary) zinc grains and possibly aluminum phases (aluminum grains).
  • These secondary zinc granules are not to be confused with the primarily precipitated zinc granules, as their volume is several orders of magnitude smaller than that of the primary zinc granules. While the primary zinc grains can sometimes have a diameter of more than 30 ⁇ m, the diameter of the secondary zinc grains in the eutectic phases is usually up to 3 ⁇ m.
  • these secondary phases are precipitated during solidification of the eutectic. The eutectic is the last phase to separate out of the melt.
  • Hypo- or hyper-eutectic phase is eutectic that forms surrounded by either the alpha or beta component of the binary phase diagram (to the left or right of the melt eutectic composition).
  • the layered structure of a Zn-Mg-Al coating shows an enrichment of eutectic phases surrounding the zinc grains, which does not cover the entire surface but is distributed over the entire surface.
  • the eutectic and the eutectic phases are magnesium-rich phases. The enrichment of eutectic phases distributed over the entire surface can average up to 30%.
  • adding magnesium to the melt improves corrosion resistance and reduces tool wear during forming.
  • the improved corrosion behavior is attributed to the microstructure of the eutectic phases in the coating.
  • Essentially dense eutectic structures consisting of zinc, zinc-magnesium-(MgZn2- and/or Mg2Znll-) and optionally aluminum phases, so that layered double hydroxides, consisting of aluminum and magnesium hydroxides, are formed, which slow down the further corrosion process. Accordingly, an increase in the area ratio of the dense eutectic phases on the coating provides an improvement in corrosion resistance.
  • the more efficient forming behavior of the Zn-Mg-Al coating is not yet fully understood according to the prior art, 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 (MgZn2 and/or Mg2Znll) phases in the eutectic are significantly harder and therefore more resistant to wear.
  • a chemical treatment and modification of the surface of the coating is also necessary to ensure successful paint bonding to the coated steel sheets.
  • a great deal of effort is expended as part of a phosphating process, so that phosphate crystals can grow all over the surface of a coating, which is usually hot-dip coated, and in this way sufficient adhesion and a homogeneous appearance of the paint can be achieved.
  • the surface of the hot-dip coated steel sheet is “pickled” by the phosphoric acid present in the phosphating solution in order to at least partially remove/dissolve the non-reactive oxide layer that inevitably formed during the hot-dip coating process on the surface of the coating.
  • Successful conversion chemistry can only be formed after this reaction barrier (oxide layer) is/is detached, see for example DE 10 2019 204 224 A1 and EP 2 474 649 A1.
  • the object of the invention is to specify a hot-dip coated steel sheet which has improved forming behavior.
  • the hot-dip coated steel sheet comprises a Zn-Mg-Al coating which contains aluminum between 0.1 and 8.0% by weight, magnesium between 0.1 and 8.0% by weight and the remainder zinc and unavoidable impurities.
  • the coating contains zinc grains and other phases of magnesium and/or aluminum as well as eutectic structures having at least intermetallic zinc-magnesium phases, with a native oxide layer being formed on the coating.
  • the coating below the oxide layer has a surface area of at least 35%, in which an average nanohardness of at least 4 GPa prevails.
  • the coating according to the invention can show improved forming behavior compared to the coatings known from the prior art.
  • the coating surfaces are subject to mechanical stress, there is less wear and tear on the forming tool.
  • the reduction in wear can be explained by a lower coefficient of friction compared to the prior art, which in turn is closely linked to the hardness of the phases on the surface, so it can be assumed that the harder the phases in the coating or are on the surface, the lower the coefficient of friction and the better the forming properties.
  • the intermetallic zinc-magnesium (MgZn2 and/or Mg2Znll) phases are many times harder than the soft zinc grains or additional ones Magnesium and/or aluminum phases, so that the eutectic structure on the surface or near the surface (starting from the surface without an oxide layer or, if present, starting below the oxide layer) up to a maximum depth of 70 nm below the surface is decisive for the hardness properties of the coating contributes. Due to the comprehensive characterization of the intermetallic zinc-magnesium phases according to the invention, the existence of hard phases and thus a low coefficient of friction can be ensured essentially comprehensively, so that the coating according to the invention has even better forming behavior compared to the conventional Zn-Mg-Al coating points.
  • An average nanohardness of at least 4 GPa on the free surface (without a native oxide layer) or below the native oxide layer of the coating has a surface area of at least 40%, preferably at least 45%, preferably at least 50%, more preferably at least 55%, particularly preferably at least 60%.
  • the area proportion of at least 35% on the free surface (without native oxide layer) or below the native oxide layer of the coating can in particular have an average nanohardness of at least 4.5 GPa, preferably at least 5 GPa, preferably at least 5.5 GPa.
  • the native oxide layer forms during the hot-dip coating process.
  • the free surface of the coating means the surface without a native oxide layer or after it has been detached/removed.
  • a nanoindenter is used, for example the “Hysitron TI Premier” device from Bruker. Details on the device can be obtained from Bruker or, for example, can be accessed via the link: https://www.bruker.com/en/products-and-solutions/test-and-measurement/nanomechanical-test-svstems/hysitron- ti-premier-nanoindenter.html.
  • a certain Measuring tip for example a Berkovich tip (consisting of diamond), pressed at different depths into a sample to be examined and based on the measured force, preferably using the evaluation method according to Oliver&Pharr (method available under the link: https://www.sciencedirect.com/ topics/enqineerinq/oliver-pharr-method), a hardness can be determined.
  • CMX Continuous Measurement of X, X eg hardness, loss or storage modulus).
  • the strain rate the speed at which the deformation takes place as a result of the indentation, can be 0.11 s_1, for example.
  • two series of measurements are necessary for the simulation of the investigations: the following parameters are taken into account in the first series of measurements:
  • phase structure in the Zn-Mg-Al coating can be influenced, in particular as a function of the cooling parameters during the solidification of the molten coating. This can result in the surface and near the surface within a depth of up to 70 nm and also deeper in the solidified coating no longer predominantly large soft zinc grains but the eutectic structures in the form of hard intermetallic zinc-magnesium-(MgZn2- and/ or Mg2Znll) phases can form more.
  • magnesium contents of up to 4.0% by weight in the coating can lead to an increase in the hard intermetallic phases in the coating at an increased cooling rate of approx. 20 K/s and more to solidify the molten coating on the steel sheet.
  • magnesium contents between 4.0 and 8.0% by weight in addition to a higher magnesium content, an increase in the intermetallic phases in the coating can also occur in connection with a standard cooling process, but to ensure this, even with high Magnesium contents to take into account higher cooling rates. For example, with coating thicknesses of 7 ⁇ m and higher, larger primary zinc grains initially separate from the melt, form islands and are “washed around” or “flooded” by the remaining liquid eutectic, so that more eutectic structures form on the surface.
  • the improved or positive corrosion behavior of the coating according to the invention is due to two phenomena: 1.) the magnesium in the intermetallic zinc-magnesium phases sacrifices itself due to its baser properties compared to zinc, 2.) due to the increased surface area of the intermetallic zinc -Magnesium phases form a corrosion barrier that slows down the progressing corrosion.
  • Sheet steel is to be understood as meaning a flat steel product in strip form or sheet/plate form. It has a longitudinal extension (length), a transverse extension (width) and a height extension (thickness).
  • the steel sheet can be a hot strip (hot-rolled steel strip) or cold-rolled strip (cold-rolled steel strip), or it can be made from a hot strip or from a cold strip.
  • the thickness of the steel sheet is, for example, 0.5 to 4.0 mm, in particular 0.6 to 3.0 mm, preferably 0.7 to 2.5 mm.
  • Elements such as bismuth, zirconium, nickel, chromium, lead, titanium, manganese, silicon, calcium, tin, lanthanum, cerium and iron can be present as impurities in the coating in individual or cumulative amounts of up to 0.4% by weight.
  • the coating has a surface area of at least 35% at a depth of 20 nm below the oxide layer, in which an average nanohardness of at least 3 GPa, in particular at least 3.5 GPa, preferably at least 4 GPa, preferably of at least 4.2 GPa prevails.
  • the average nanohardness of at least 3 GPa, in particular at least 3.5 GPa, preferably at least 4 GPa, preferably at least 4.2 GPa at a depth of 20 nm below the surface of the coating can with a surface area in particular of at least 40% , preferably at least 45%, preferably at least 50%, more preferably at least 55%. If there is no native oxide layer or if it has been removed, the depth is determined from the (free) surface of the coating.
  • the coating has a surface area of at least 35% at a depth of 40 nm below the oxide layer, in which an average nanohardness of at least 2.5 GPa, in particular at least 3 GPa, preferably at least 3.2 GPa, preferably of at least 3.4 GPa.
  • the average nanohardness of at least 2.5 GPa, in particular at least 3 GPa, preferably at least 3.2 GPa, preferably at least 3.4 GPa at a depth of 40 nm below the surface of the coating can with a surface area in particular of at least 40%, preferably at least 45%, preferably at least 50%, more preferably at least 55%. If there is no native oxide layer or if it has been removed, the depth is determined from the (free) surface of the coating.
  • the coating has a surface area of at least 35% at a depth of 70 nm below the oxide layer, in which an average nanohardness of at least 2 GPa, in particular at least 2.2 GPa, preferably at least 2.4 GPa, preferably of at least 2.6 GPa.
  • the average nanohardness of at least 2 GPa, in particular at least 2.2 GPa, preferably at least 2.4 GPa, preferably at least 2.6 GPa at a depth of 70 nm below the surface of the coating can with a surface area in particular of at least 40%, preferably at least 45%, preferably at least 50%, more preferably at least 55%.
  • the coating contains additional elements such as aluminum with a content of between 0.1 and 8.0% by weight and magnesium with a content of between 0.1 and 8.0% by weight. If improved corrosion protection is provided, the coating also has magnesium with a content of at least 0.3% by weight. In particular, the coating contains aluminum and magnesium, each with at least 0.5% by weight, in order to be able to provide an improved cathodic protection effect.
  • Aluminum and magnesium in the coating are preferably limited to a maximum of 3.5% by weight each. Most preferably magnesium is present in the coating between 1.0 and 2.5% by weight.
  • the coating has a thickness between 2 and 20 gm, in particular between 4 and 15 gm, preferably between 5 and 12 gm.
  • the hot-dip coated steel sheet can be skin-passed.
  • a surface structure is embossed into the coating, which can be, for example, a deterministic surface structure.
  • a deterministic surface structure is to be understood in particular as meaning regularly recurring surface structures which have a defined shape and/or design 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, the introduction of a stochastic surface structure is also conceivable.
  • the high density or high area percentage of the hard intermetallic zinc-magnesium phases favors the corrosion behavior and, after surface modification of the coating, for example as part of a treatment with an inorganic acid, can have a surface morphology that achieves a number of advantages.
  • the treatment with an inorganic acid can not only completely free the surface of the coating from the native oxide layer, but also cause the coating below the oxide layer to be removed to a depth of at least 5 nm and more.
  • the inorganic acid used can be 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 , H 3 PO 3 , HF, or a mixture of 2 or more of these acids as an aqueous solution.
  • An aqueous solution of an inorganic acid with a pH between 0.01 and 2 can be used.
  • the coating can be wetted with the aqueous solution of an inorganic acid for between 0.5 and 600 s and/or at a temperature of 10 to 90°C.
  • the exposed hard intermetallic zinc-magnesium phases on the surface of the coating have a developed interfacial ratio Sdr of at least 5.5%, in particular at least 6%, preferably at least 7%, based on a scanning area of 5 ⁇ 5 ⁇ m 2 on.
  • the exposed zinc grains on the surface on the other hand, only have a developed interfacial ratio Sdr of 5% and less.
  • Sdr developed interface ratio
  • AFM can also be used to determine the mean roughness of the exposed hard zinc-magnesium intermetallic phase on the surface of the coating, which is at least 7.5 nm.
  • the mean roughness of the hard intermetallic zinc-magnesium phases can be at least 7.9 nm, preferably at least 8.4 nm.
  • the hot-dip coated steel sheet is phosphated.
  • Phosphating is common practice.
  • an area-wide homogeneous phosphate layer is formed, with the zinc phosphate crystals having a size of up to 3 ⁇ m, which differ from one another by up to 20% on average, and in particular are oriented in the same way.
  • FIG. 1 Hardness mappings generated by means of a nanoindenter at a depth of 20 nm, 40 nm and 70 nm within a standard Zn-Mg-Al coating
  • FIG. 2 hardness mappings generated by means of nanoindenters at a depth of 20 nm, 40 nm and 70 nm within a Zn-Mg-Al coating according to an embodiment according to the invention
  • FIG. 3 An SEM image of the surface before and after treatment with an inorganic acid of a standard Zn-Mg-Al coating, left images, and an SEM image of the surface before and after treatment with an inorganic acid of a Zn-Mg-Al coating according to an embodiment of the invention, right-hand photographs.
  • the samples were taken out of the molten pool and fed to a stripping device, which acted on both sides of the liquid melt on the samples and stripped off excess melt, with a gas flow being set in the stripping device so that after the coating had solidified, a thickness of 7 pm set.
  • the wiping was carried out in an inert atmosphere containing 5% H 2 , the balance N 2 and unavoidable components, and N 2 was used as the gas for wiping.
  • the part of the samples (1) that had gone through the first melt was conventionally cooled by the inert atmosphere and due to the acting gas flow at a cooling rate of about 7 °C/s.
  • the other part of the samples (2), which had passed through the first melt was actively cooled at a cooling rate of > 20 °C/s.
  • some of the samples (3) coming from the second melt were conventionally cooled and the other part of the samples (4) were cooled at a cooling rate of >20° C./s.
  • the different samples (1) to (4) were identified using the Bruker “Hysitron TI Premier” nanoindenter. The study was carried out as described above. As a result, a spatially and depth-resolved representation (nanoindentation), so-called plate mapping, was made at a depth of 20 nm, 40 nm and 70 nm below the native oxide layer on an examined area of 65 x 65 pm 2 of the local nanohardness, see Figure 1 for a representation in the mean of the measured samples (1) and FIG. 2 for a representation in the mean of the measured samples (2). The results of samples (3) and (4) were of the order of magnitude of the results of samples (2). Using the nanoindenter and the evaluation method according to Oliver&Pharr, the average nanohardness and the corresponding surface area can generally be determined over an area of 65 x 65 ⁇ m 2 depending on location and depth.
  • the average nanohardness of at least 3 GPa at a depth of 20 nm below the native oxide layer of the coating is represented with a surface area of at least 35%.
  • the coating has a surface area of at least 35% at a depth of 40 nm below the native oxide layer of the coating, in which an average nanohardness of at least 2.5 GPa prevails.
  • the coating has a surface area of at least 35% at a depth of 70 nm below the oxide layer of the coating, in which an average nanohardness of at least 2 GPa prevails.
  • an average nanohardness of at least 2 GPa prevails.
  • Samples (1) to (4) were further examined by treating their surfaces with an inorganic acid under laboratory conditions.
  • the samples were degreased with an alkaline cleaning agent and then immersed in a solution with 12 ml/l sulfuric acid at a temperature of 20 °C for 5 s. Afterward rinsed with water and isopropanol. All tests were carried out under normal air atmosphere.
  • the magnesium in the intermetallic zinc-magnesium phases dissolves preferentially in an acidic environment, so that such an acidic treatment of the coating according to the invention leaves behind a surface that is comparatively richer in aluminum.
  • the aluminum on the surface of the coating also has the advantage that it can be better dissolved by alkaline process media such as cleaners or adhesives, and the surface of the coating can thus be better activated by such process media.
  • the acid treated eutectic at the surface of the coating has an average roughness of at least 7.5 nm as measured by AFM.
  • the average roughness of the acid-treated eutectic on the surface of the conventional coating is less than 4.9 nm.

Landscapes

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

Abstract

L'invention concerne une tôle d'acier galvanisée par immersion à chaud ayant un revêtement de Zn-Mg-Al comprenant entre 0,1 et 8,0 % en poids d'aluminium, entre 0,1 et 8,0 % en poids de magnésium, et le reste étant du zinc et des impuretés inévitables, le revêtement contenant des grains de zinc et d'autres phases de magnésium et/ou d'aluminium ainsi que des structures eutectiques comprenant au moins des phases intermétalliques de zinc-magnésium, une couche d'oxyde natif étant formée sur le revêtement. Selon l'invention, le revêtement sous la couche d'oxyde natif présente un rapport surfacique d'au moins 35 % dans lequel il existe une nanodureté moyenne d'au moins 4 GPa.
EP22717072.7A 2021-03-29 2022-03-18 Tôle d'acier galvanisée par immersion à chaud Pending EP4314374A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102021107873.3A DE102021107873A1 (de) 2021-03-29 2021-03-29 Schmelztauchbeschichtetes Stahlblech
PCT/EP2022/057164 WO2022207365A1 (fr) 2021-03-29 2022-03-18 Tôle d'acier galvanisée par immersion à chaud

Publications (1)

Publication Number Publication Date
EP4314374A1 true EP4314374A1 (fr) 2024-02-07

Family

ID=81326700

Family Applications (1)

Application Number Title Priority Date Filing Date
EP22717072.7A Pending EP4314374A1 (fr) 2021-03-29 2022-03-18 Tôle d'acier galvanisée par immersion à chaud

Country Status (5)

Country Link
US (1) US20240229210A9 (fr)
EP (1) EP4314374A1 (fr)
CN (1) CN117136251A (fr)
DE (1) DE102021107873A1 (fr)
WO (1) WO2022207365A1 (fr)

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006051543A (ja) 2004-07-15 2006-02-23 Nippon Steel Corp 冷延、熱延鋼板もしくはＡｌ系、Ｚｎ系めっき鋼板を使用した高強度自動車部材の熱間プレス方法および熱間プレス部品
EP2474649A1 (fr) 2011-01-05 2012-07-11 Voestalpine Stahl GmbH Procédé de traitement de surface d'un substrat ayant un revêtement de protection
KR101767788B1 (ko) 2015-12-24 2017-08-14 주식회사 포스코 내마찰성 및 내백청성이 우수한 도금 강재 및 그 제조방법
WO2017203310A1 (fr) 2016-05-24 2017-11-30 Arcelormittal Procédé de fabrication d'une tôle d'acier twip à microstructure austénitique
KR102031466B1 (ko) 2017-12-26 2019-10-11 주식회사 포스코 표면품질 및 내식성이 우수한 아연합금도금강재 및 그 제조방법
DE102019204224A1 (de) 2019-03-27 2020-10-01 Thyssenkrupp Steel Europe Ag Verfahren zur Neukonditionierung von feuerverzinkten Oberflächen
CN110983224B (zh) 2019-12-16 2021-07-23 首钢集团有限公司 一种热镀锌铝镁镀层钢及其制备方法

Also Published As

Publication number Publication date
DE102021107873A1 (de) 2022-09-29
CN117136251A (zh) 2023-11-28
US20240133012A1 (en) 2024-04-25
US20240229210A9 (en) 2024-07-11
WO2022207365A1 (fr) 2022-10-06

Similar Documents

Publication Publication Date Title
EP1888798B1 (fr) Alliage d'aluminium pour paliers lisses
EP2588646B1 (fr) Procédé de phosphatation sélective d'une construction métallique composite
DE112008002388B4 (de) Mit einer Magnesium-Titan-Mischkristalllegierung beschichtetes Substrat und Verfahren zur Herstellung eines solchen Substrats
EP1987172A2 (fr) Substrat anticorrosif et son procede de fabrication
DE102019214136A1 (de) Stahlblech mit einer deterministischen Oberflächenstruktur
DE102020200321A1 (de) Verfahren zur Herstellung eines oberflächenveredelten und oberflächenkonditionierten Stahlblechs
DE102019214133A1 (de) Stahlblech mit einer deterministischen Oberflächenstruktur
EP4076777A1 (fr) Feuille de métal présentant une structure de surface déterministe et procédé de production d'un composant de métal en feuille formé et revêtu
DE3242625A1 (de) Verfahren zur herstellung von feuerverzinkten stahlblechen
DE69520350T2 (de) Galvanisiertes stahlblech und verfahren zur herstellung
EP3408431A1 (fr) Bande d'alliage en aluminium pour liaison adhésive
AT514229B1 (de) Verfahren zur Oberflächenbehandlung eines metallischen Substrats
DE68908443T2 (de) Korrosionsbeständige Legierungen auf Aluminiumbasis.
DE2632439A1 (de) Verfahren zur herstellung eines mit aluminium oder einer aluminiumlegierung beschichteten stahlbleches
DE102011009244A1 (de) Opferanodenbeschichtungen für Magnesiumlegierungen
DE102020107653A1 (de) Verfahren zum Erzeugen einer Phosphatierschicht und mit einer Phosphatierschicht versehenes Stahlflachprodukt
EP4314374A1 (fr) Tôle d'acier galvanisée par immersion à chaud
DE69903940T2 (de) Oberflächenbehandeltes stahlblech und verfahren zu seiner herstellung
WO2023088783A1 (fr) Procédé de production d'une tôle d'acier revêtue par immersion à chaud et tôle d'acier revêtue par immersion à chaud
DE102017214527A1 (de) Verfahren zur Beschichtung von warmumzuformenden Stahlflachprodukten
DE102020208991A1 (de) Verfahren zur Herstellung eines schmelztauchbeschichteten Stahlblechs und schmelztauchbeschichtetes Stahlblech
WO2021144164A1 (fr) Procédé de production d'une feuille d'acier traitée en surface et conditionnée en surface
DE102020214293B4 (de) Stahlflachprodukt mit verbesserter Zinkbeschichtung
EP2571653A1 (fr) Procédé de fabrication d'une tôle composite métallique multicouche en utilisant une suspension de particules; tôle composite correspondante
EP4093896A1 (fr) Composant en acier comprenant une couche anti-corrosion contenant du manganèse

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: UNKNOWN

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20230825

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)