EP3730664A1 - Tôle d'acier plaquée d'alliage d'aluminium fondu ayant une excellente résistance à la corrosion et soudabilité et son procédé de fabrication - Google Patents

Tôle d'acier plaquée d'alliage d'aluminium fondu ayant une excellente résistance à la corrosion et soudabilité et son procédé de fabrication Download PDF

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EP3730664A1
EP3730664A1 EP18892672.9A EP18892672A EP3730664A1 EP 3730664 A1 EP3730664 A1 EP 3730664A1 EP 18892672 A EP18892672 A EP 18892672A EP 3730664 A1 EP3730664 A1 EP 3730664A1
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Prior art keywords
steel sheet
aluminum alloy
hot
plated steel
interface
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German (de)
English (en)
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EP3730664A4 (fr
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Suk-Kyu Lee
Il-Jeong Park
Myung-Soo Kim
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Posco Holdings Inc
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Posco Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/12—Aluminium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/10—Alloys based on aluminium with zinc as the next major constituent
    • 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
    • C23C2/29—Cooling or quenching
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36—Elongated material
    • C23C2/40—Plates; Strips
    • 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
    • C23C2/50—Controlling or regulating the coating processes
    • C23C2/52—Controlling or regulating the coating processes with means for measuring or sensing
    • C23C2/526—Controlling or regulating the coating processes with means for measuring or sensing for visually inspecting the surface quality of the substrate
    • 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
    • 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
    • C23C28/028—Including graded layers in composition or in physical properties, e.g. density, porosity, grain size
    • 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 present invention relates to a hot-dip aluminum alloy-plated steel sheet having excellent corrosion resistance and weldability.
  • a molten Al-Zn-base plated steel sheet has both sacrificial corrosion resistance of Zn and high corrosion resistance of Al and thus has excellent corrosion resistance as compared to other hot-dip galvanized steel sheets.
  • Patent Document 1 discloses a technology of improving corrosion resistance by alloy-plating formed of Al: 25 wt% to 75 wt%, Mg: 0.1 wt% to 10 wt%, Si: 1 wt% to 7.5 wt%, Cr: 0.05 wt% to 5 wt%, a remainder of Zn and inevitable impurities.
  • binding of a plating layer with a base steel sheet may not be sufficient depending on the plating bath, resulting in a possibility that a problem of poor plating adhesion, such as delamination of the plating layer, or the like, may arise.
  • Patent Document 1 Korean Patent Laid-Open Publication No. 10-2011-0088573
  • An aspect of the present invention is to provide a hot-dip aluminum alloy-plated steel sheet having excellent corrosion resistance and weldability.
  • Another aspect of the present invention is to provide a hot-dip aluminum alloy-plated steel sheet having excellent plating adhesion.
  • a hot-dip aluminum alloy-plated steel sheet having excellent corrosion resistance and weldability includes a hot-dip aluminum alloy plating film on a base steel sheet, and the plating film comprises an interface alloy layer present at an interface with the steel sheet and a plating upper layer present on the interface alloy layer, wherein a phase having an atomic ratio of Fe and Al of between 1:2.8 to 1:3.3 occupies at least 70% by area of phases present within 1 ⁇ m in an interface alloy layer direction from a boundary between the interface alloy layer and the base steel sheet.
  • a hot-dip aluminum alloy-plated steel sheet having excellent corrosion resistance and weldability includes a hot-dip aluminum alloy plating film on a base steel sheet, and the plating film comprises an interface alloy layer present at an interface with the steel sheet and a plating upper layer present on the interface alloy layer, wherein a phase having an atomic ratio of Fe and Al of between 1:2.2 to 1:2.7 occupies 10% or less by area of the interface alloy layer.
  • a hot-dip aluminum alloy-plated steel sheet having excellent corrosion resistance and weldability includes a hot-dip aluminum alloy plating film on a base steel sheet, wherein the interface alloy layer has a single-layer structure, and an atomic ratio of Fe and Al is between 1:2.8 to 1:3.3 when a composition of the interface alloy layer is analyzed in the central portion of a thickness direction.
  • a method for manufacturing a hot-dip aluminum alloy-plated steel sheet includes preparing a base steel sheet; dipping the prepared base steel sheet in a molten aluminum alloy-plating bath to plate; and cooling, wherein a temperature of the plating bath is a melting point thereof +30°C or less, and the cooling is performed such that a surface temperature of the base steel sheet released from the plating bath drops below the melting point of the plating bath in 5 seconds.
  • a hot-dip aluminum alloy-plated steel sheet according to an embodiment of the present invention has an advantage of excellent weldability and corrosion resistance.
  • a hot-dip aluminum alloy-plated steel sheet having excellent weldability and corrosion resistance as an aspect of the present invention will be first described in detail.
  • a hot-dip aluminum alloy-plated steel sheet includes a base steel sheet and a hot-dip aluminum alloy-plating film (hereinafter, referred as a "plating film").
  • the plating film may be formed on one surface or both surfaces of the base steel sheet.
  • the plating film is formed of an interface alloy layer present at an interface with the steel sheet and a plating upper layer present on the interface alloy layer.
  • a Fe 2 Al 5 phase with a high Fe content is formed in a position close to a base steel sheet of an interface alloy layer.
  • a FeAl 3 phase or a phase having a similar chemical composition ratio is formed in a position close to a base steel sheet of an interface alloy layer.
  • FIG. 1 illustrates an interface alloy layer of a conventional aluminum alloy-plated steel sheet, and is a photographic image of a cross-section of an interface alloy layer of Comparative Example 1 observed by a scanning electron microscope (SEM).
  • FIG. 2 is a photographic image of an interface alloy layer of an aluminum alloy-plated steel sheet of Inventive Example 2, observed by SEM.
  • An interface alloy layer of a conventional aluminum alloy-plated steel sheet illustrated in FIG. 1 is shown to be formed of multilayers.
  • a lower portion of the interface alloy layer is formed of Fe 2 Al 5 , an Fe-Al-base hard alloy phase.
  • Such a Fe-Al-base hard alloy phase may cause delamination of a plating layer or liquid metal embrittlement (LME) during spot welding.
  • LME liquid metal embrittlement
  • an interface alloy layer has a single layer structure.
  • Such a single-layer interface alloy layer is mainly formed of FeAl 3 . Accordingly, a Fe-Al-base hard alloy phase, such as Fe 2 Al 5 , does not substantially exist in a position close to a base steel sheet of the interface alloy layer. Further, occurrence of LME can be effectively prevented during spot welding.
  • the expression that a FeAl 3 phase is formed at a position close to the base steel sheet in the interface alloy layer in a first embodiment of the present invention means that a FeAl 3 phase occupies at least 70% by area of phases present within 1 ⁇ m in a direction toward the interface alloy layer from a boundary between the interface alloy layer and the base steel sheet.
  • the interface alloy layer may have a single layer structure and may have a structure of two layers or more; however, a FeAl 3 phase is formed in a position close to the base steel sheet.
  • a content of Al may be higher in all formed layers as compared to that in the FeAl 3 phase.
  • FeAl 3 phase is not limited to a phase in which Fe and Al are necessarily combined at a ratio of 1:3, but refers to a phase in which an atomic ratio of Fe and Al (Fe content in weight/atomic weight of Fe:Al content in weight/atomic weight of Al) is 1:2.8 to 1:3.3. Further, the expression is to define a ratio between Fe and Al, and it should be noted that the expression does not exclude the fact that additional components derived from a plating bath, a base steel sheet, or the like, are included therein.
  • Unlimited examples of the components, which can be additionally included in the FeAl 3 phase are silicon (Si), manganese (Mn), or the like.
  • a percentage of Fe 2 Al 5 contained in the interface alloy layer is limited to 10% or less, preferably 5% or less by area.
  • Fe 2 Al 5 phase refers to a phase having an atomic ratio of Fe and Al of 1:2.2 to 1:2.7.
  • the interface alloy layer may have a single layer structure and may have a structure of two layers or more; however, a FeAl 3 phase is formed in a position close to the base steel sheet.
  • a content of Al may be higher in all formed layers as compared to that in the FeAl 3 phase (that is, Al is included in all formed layers such that an atomic ratio of Fe and Al is greater than 1:2.8).
  • the interface alloy layer may substantially be formed of a single layer.
  • Al content may correspond to the content in a FeAl 3 content.
  • the composition of the central portion in the thickness direction may be obtained by selecting 5 random points in the central portion in the thickness direction and component-analyzing the same with EDS followed by calculating an average value thereof.
  • the expression that an interface alloy layer has a single layer structure may mean that distinction of layers is not observed in the interface alloy layer when a hot-dip aluminum alloy-plated steel sheet is cut in a thickness direction to observe a cross-section thereof using a field emission scanning electron microscope (FE-SEM) at 3,000 ⁇ magnification.
  • FE-SEM field emission scanning electron microscope
  • the plating film may include, by weight%, Al: 50% to 90%, Zn: 2% to 35%, Si: 3% to 15% and Fe: 0.1% to 5%.
  • the plating film of the present invention may be analyzed by dissolving a plated upper layer and the interface alloy layer with hydrochloric acid and analyzing thus-obtained solution using an inductively coupled plasma (ICP) method.
  • ICP inductively coupled plasma
  • the analysis method is not necessarily limited thereto.
  • Al is added to form a high melting point alloy phase together with iron.
  • an added amount of Al is too small, a high melting point alloy phase is poorly formed, and welding liquid metal embrittlement may occur.
  • an Al content may be 50 wt% or more, 55 wt% or more or 60 wt% or more.
  • an excessive Al content may deteriorate cross-sectional corrosion resistance.
  • the Al content may be 90 wt% or less, 80 wt% or less, or 75 wt% or less.
  • Zn is added for sacrificed protection against corrosion in cross-section.
  • a Zn content be 2 wt% or more; the Zn content may be 10 wt% or more, or 20 wt% or more.
  • an excessive content thereof may cause LME during welding.
  • the Zn content may be 35 wt% or less, 30 wt% or less or 25 wt% or less.
  • Si is added to lower a melting point of a plating bath and improve plating adhesion.
  • an added amount of Si is too small, an Al-Fe alloy phase is excessively formed, thereby deteriorating plating adhesion.
  • an Si content may be 3 wt% or more, 5 wt% or more or 6 wt% or more.
  • an excessive amount thereof may increase a melting point of the plating bath and extremely prevent formation of an Al-Fe alloy phase.
  • an Si content may be 15 wt% or less, 12 wt% or less or 10 wt% or less.
  • Fe reacts with Al to prevent LME by forming a Fe-Al intermetallic compound having a high melting point.
  • an Fe content may be 0.1 wt% or more, 1 wt% or more or 3 wt% or more.
  • an excessive content thereof may cause excessive formation of the Al-Fe alloy phases, thereby deteriorating plating adhesion.
  • an Si content may be 5 wt% or less, 4.5% or less or 4 wt% or less.
  • the remaining part is inevitable impurities.
  • undesired impurities may be inevitably introduced from a raw material or surrounding environment and thus cannot be excluded.
  • the impurities are well known to one of ordinary skill in the art and thus are not particularly mentioned in the present invention.
  • the plating film may further contain Mg: 0.5 wt% to 5 wt%.
  • Mg is added to improve corrosion resistance of surfaces and cross-sections. To sufficiently obtain such an effect, 0.5 wt% or more, 1 wt% or more or 2 wt% or more of Mg may be added. However, an excessive content thereof may lead to LME during welding. In this regard, a Mn content may be 5 wt% or less, 4 wt% or less or 3 wt% or less.
  • an Fe content in the interface alloy layer is preferably 45 wt% or less.
  • spot analysis using energy dispersive spectroscopy may be employed.
  • the spot analysis involves selecting 5 random points in a central portion in a thickness direction of the interface alloy layer and component-analyzing the same with EDS followed by calculating an average value thereof.
  • a value of the Fe content in the interface alloy layer exceeding 45 wt% indicates that an Fe-Al-base hard alloy phase is present in the interface alloy layer.
  • such an Fe-Al-base hard alloy phase is problematic in that spot weldability and plating adhesion during processing is deteriorated. In this regard, it is preferable that such a region does not exist.
  • an average Si content in the interface alloy layer may be twice an average Si content in the plating upper layer or more, preferably three times or more, more preferably seven times or more, the most preferably ten times or more.
  • alloy phases may be excessively formed.
  • a specific method for measuring an average Si content in the plating upper layer and the interface alloy layer is not particularly limited, but may, for example, involve dissolving the plating upper layer in chromic acid and measuring by wet analysis (ICP), while an average Si content in the interface alloy layer may be measured by dissolving the interface alloy layer in hydrochloric acid followed by wet analysis (ICP).
  • the Si content in the plating upper layer be 0.7 wt% to 1 wt%, and that in the interface alloy layer be 7 wt% to 12 wt%.
  • the interface alloy layer may have an average thickness of 7 ⁇ m or less (excluding 0 ⁇ m), preferably 5 ⁇ m or less (excluding 0 ⁇ m).
  • the thickness exceeds 7 ⁇ m, plating adhesion may be deteriorated during processing.
  • a lower limit of the average thickness of the interface alloy layer there is no limitation on a lower limit of the average thickness of the interface alloy layer; however, when the thickness is too small, LME resistance may not be prevented during welding. In consideration thereof, the lower limit may be determined to 1 ⁇ m.
  • the hot-dip aluminum alloy-plated steel sheet of the present invention may be manufactured by various methods, and the manufacturing methods are not particularly limited. However, as a preferable example, the following method may be employed.
  • a base steel sheet is prepared.
  • a type of the base steel sheet is not particularly limited as long as it is acknowledged as being applied to the technical field to which the present invention pertains.
  • plating bath a hot-dip aluminum alloy-plating bath
  • a composition of the plating bath may be, for example, Al: 50% to 90%, Zn: 2% to 35%, Si: 3% to 15% and Fe: 0.1 ⁇ 5% by weight%.
  • a temperature of the plating bath may affect not only characteristics of the base steel sheet but also a structure of the interface alloy layer. More specifically, when the plating bath temperature is higher than 30°C above a melting point of the plating bath, a structure of residual austenite and martensite is decomposed, thereby deteriorating properties of the base steel sheet. Further, formation of Fe 2 Al 5 formed by alloying with molten aluminum on a surface of the base steel sheet introduced into the plating bath is facilitated, which may result in multilayer interface alloy layer. Accordingly, the temperature of the plating bath may be a melting point thereof +30°C or below, a melting point thereof +25°C or below, or a melting point thereof +20°C.
  • an adhesion amount may be controlled by wiping using nitrogen gas during plating.
  • the plating layer is cooled after the plating is performed. Such cooling also has a great impact on a structure of the interface alloy layer. It is preferable that the cooling is performed such that a temperature of the steel sheet surface released from the plating bath drops below the melting point of the plating bath within 5 sec, 4 sec or 3 sec. When the plating layer is not solidified within a short period of time, a multilayer interface alloy layer may be obtained, or an Fe-Al alloy phase continues to grow, thereby deteriorating plating adhesion.
  • a cooling speed at a temperature equivalent to or below the melting point of the plating bath is not particularly limited, but may be, for example, 5°C/sec to 20°C/sec until the plating upper layer is completely cooled.
  • the speed is less than 5°C/sec, the plating layer may be adsorbed on a top roll, or the like, whereas the speed exceeding 20°C/sec may result in generation of a wave pattern on the surface thereof.
  • a giga-level steel material (a steel material having strength of 1 GPa or more; the steel material used herein has strength of 1.18 GPa) for vehicles, having a thickness of 1.4 mm and including C: 0.15%, Si: 1.5%, Mn: 2.5%, Cr: 0.4%, a remainder of Fe and inevitable impurities was prepared as a base steel sheet, and immersed and ultrasonic-cleaned to remove foreign substances, such as rolling oil, from a surface.
  • a heat treatment was performed in a 750°C reduction environment to secure mechanical characteristics of the steel sheet in a general molten plating field, followed by dipping the same in a plating bath having the composition and temperature shown in Table 1 below to manufacture a hot-dip aluminum alloy-plated steel sheet.
  • Each hot-dip aluminum alloy-plated steel sheet was measured in terms of properties thereof, and corrosion resistance, weldability and plating adhesion were evaluated. Results are shown in Table 3 below.
  • the corrosion resistance evaluation was measured by charging the hot-dip aluminum alloy-plated steel sheet in a salt spray tester, and 5% salt water (35°C, pH 6.8) was sprayed at 2 mL/80 cm 2 per hour. After 1200 hours from charging, corrosion products were removed, and a maximum depth of a hole formed on the base steel sheet was measured. As a result of the measurement, 300 ⁇ m or less was evaluated as “excellent”, 300 ⁇ m to 600 ⁇ m was evaluated as "normal” while 600 ⁇ m was evaluated as “poor.”
  • a sealer type D for vehicle structures was maintained at 175°C for 25 minutes and cured to perform a 90° bending test.
  • a size of a sample was 30 mm ⁇ 75 mm, and a surface area of sealer application was 10 mm ⁇ 40 mm while a thickness was 10 mm. It was evaluated as "excellent" when shear adhesive strength was 24.5 MPa or more and "poor” in the case of shear adhesive strength less than 24.5 MPa.
  • Interface alloy layer Plating upper layer Remark Entire interface alloy layer Within 1 ⁇ m from boundary with steel sheet Struc ture Thick ness ( ⁇ m) Fe content (wt%) Si content (wt%) Fe 2 Al 5 percentage (area %) FeAl 3 percentage (area%) Si content (wt%) 1 *SL 4 32 11 1 99 1 ***IE 1 2 **ML 5 48 11 20 80 1 ****CE1 3 ML 2 40 25 12 88 2 CE 2 4 SL 4 38 9 2 98 0.7 IE 2 5 ML 5 46 9 17 83 0.7 CE 3 6 SL 3 36 12 9 91 1 IE 3 7 ML 8 55 4 30 70 0.1 CE 4 8 ML 7 48 7 15 85 0.8 CE 5 9 SL 5 40 7 3 97 0.8 IE 4 10 ML 7 50 7 13 87 0.8 CE 6 11 SL 3 30 10 1 99 1 IE 5 12 ML 2 45 9 14 86 1 CE 7 13 SL 4 31 9 2 98 0.7 IE 6 14 ML 5 45 8 22 78 0.7 CE 8 *SL
  • FIGS. 1 and 2 are respective photographic images of cross-sections of plating films of Comparative Example 1 and Inventive Example 2, observed by SEM. As illustrated therein, Comparative Example 1 has a multilayer structure while Inventive Example 2 has a single layer structure.
  • FIG. 3 is a photographic image of a cross-section of Inventive Example 4 after welding, observed by SEM
  • FIG. 4 is a photographic image of a cross-section of Comparative Example 7 after welding, observed by SEM. Based on FIGS. 3 and 4 , Inventive Example 4 satisfying the requirements suggested in the present disclosure shows improved weldability while LME is exhibited in Comparative Example 7.

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EP18892672.9A 2017-12-22 2018-12-17 Tôle d'acier plaquée d'alliage d'aluminium fondu ayant une excellente résistance à la corrosion et soudabilité et son procédé de fabrication Pending EP3730664A4 (fr)

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KR1020170177677A KR102043519B1 (ko) 2017-12-22 2017-12-22 내식성 및 용접성이 우수한 용융 알루미늄 합금 도금강판 및 그 제조방법
PCT/KR2018/015998 WO2019124901A1 (fr) 2017-12-22 2018-12-17 Tôle d'acier plaquée d'alliage d'aluminium fondu ayant une excellente résistance à la corrosion et soudabilité et son procédé de fabrication

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WO2024128613A1 (fr) * 2022-12-16 2024-06-20 주식회사 포스코 Tôle d'acier plaquée et son procédé de fabrication

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KR100324893B1 (ko) * 1996-12-13 2002-08-21 닛신 세이코 가부시키가이샤 내식성및표면외관이양호한융용아연-알루미늄-마그네슘도금강판및그제조법
JP4136286B2 (ja) * 1999-08-09 2008-08-20 新日本製鐵株式会社 耐食性に優れたＺｎ−Ａｌ−Ｍｇ−Ｓｉ合金めっき鋼材およびその製造方法
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JP4584179B2 (ja) * 2006-04-13 2010-11-17 Ｊｆｅ鋼板株式会社 耐食性および加工性に優れた溶融Ｚｎ−Ａｌ合金めっき鋼板の製造方法
JP5476676B2 (ja) * 2008-04-22 2014-04-23 新日鐵住金株式会社 ホットプレス部材及びその製造方法
KR101008042B1 (ko) * 2009-01-09 2011-01-13 주식회사 포스코 내식성이 우수한 알루미늄 도금강판, 이를 이용한 열간 프레스 성형 제품 및 그 제조방법
EP2388353B1 (fr) 2009-01-16 2014-11-12 Nippon Steel & Sumitomo Metal Corporation MATÉRIAU ACIER ENDUIT D' ALLIAGE Zn-Al-Mg-Si-Cr PAR IMMERSION A CHAUD AYANT UNE EXCELLENTE RÉSISTANCE À LA CORROSION
JP5430022B2 (ja) * 2011-12-12 2014-02-26 Ｊｆｅスチール株式会社 Ａｌ系めっき鋼材及びその製造方法
KR20140066020A (ko) * 2012-11-22 2014-05-30 현대제철 주식회사 희생 방식성이 우수한 용융 Ａｌ-Ｍｇ-Ｓｉ계 합금 도금강판 및 그 제조 방법
EP3124642B1 (fr) * 2014-03-28 2018-12-19 Nippon Steel & Sumitomo Metal Corporation Tôle d'acier revetue avec des quasi-cristaux
KR101569509B1 (ko) * 2014-12-24 2015-11-17 주식회사 포스코 프레스성형시 내파우더링성이 우수한 hpf 성형부재 및 이의 제조방법
RU2710813C1 (ru) * 2016-05-10 2020-01-14 Ниппон Стил Корпорейшн Горячештампованная сталь

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KR102043519B1 (ko) 2019-11-12
WO2019124901A1 (fr) 2019-06-27
EP3730664A4 (fr) 2020-12-02
KR20190076129A (ko) 2019-07-02
CN111511955B (zh) 2023-04-14

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