WO2021106260A1 - Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板 - Google Patents

Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板 Download PDF

Info

Publication number
WO2021106260A1
WO2021106260A1 PCT/JP2020/025968 JP2020025968W WO2021106260A1 WO 2021106260 A1 WO2021106260 A1 WO 2021106260A1 JP 2020025968 W JP2020025968 W JP 2020025968W WO 2021106260 A1 WO2021106260 A1 WO 2021106260A1
Authority
WO
WIPO (PCT)
Prior art keywords
region
hot
dip galvanized
steel sheet
phase
Prior art date
Application number
PCT/JP2020/025968
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
ゆきの 石川
浩雅 莊司
哲也 鳥羽
泰平 金藤
信之 下田
Original Assignee
日本製鉄株式会社
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
Priority claimed from JP2019216686A external-priority patent/JP7381865B2/ja
Priority claimed from JP2019216685A external-priority patent/JP7381864B2/ja
Application filed by 日本製鉄株式会社 filed Critical 日本製鉄株式会社
Priority to KR1020227016563A priority Critical patent/KR102658299B1/ko
Priority to CN202080080847.9A priority patent/CN114729437A/zh
Priority to TW109131294A priority patent/TWI815038B/zh
Publication of WO2021106260A1 publication Critical patent/WO2021106260A1/ja

Links

Images

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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C18/00—Alloys based on zinc
    • C22C18/04—Alloys based on zinc with aluminium 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
    • C23C2/14—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
    • 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

Definitions

  • the present invention relates to a Zn—Al—Mg-based hot-dip galvanized steel sheet.
  • the present application claims priority based on Japanese Patent Application No. 2019-216685 and Japanese Patent Application No. 2019-216686 filed in Japan on November 29, 2019, the contents of which are incorporated herein by reference.
  • Zn-Al-Mg-based hot-dip galvanized steel sheets which have higher corrosion resistance than hot-dip galvanized steel sheets, are widely used in various manufacturing industries such as building materials, home appliances, and automobile fields, and their usage has been increasing in recent years. ..
  • the hot-dip galvanized layer is subjected to processes such as printing and painting to produce characters, patterns, design images, etc. It may appear on the surface of the hot-dip galvanized layer.
  • the ink may reduce the corrosion resistance of the hot-dip plating layer.
  • the design or the like is revealed by grinding the hot-dip plating layer, the durability of the design or the like is excellent, but the thickness of the hot-dip galvanizing layer at the ground portion is significantly reduced, so that the corrosion resistance is inevitably lowered and the plating characteristics are lowered. Is a concern.
  • Patent Document 1 describes a Zn—Al—Mg-based hot-dip galvanized steel sheet having a satin-like appearance with fine texture and many smooth glossy portions, that is, a large number of white portions per unit area and gloss.
  • a Zn—Al—Mg-based hot-dip galvanized steel sheet having a good satin-like appearance in which the proportion of the area of the portion is large is described.
  • Patent Document 1 describes that an unfavorable satin finish is a state in which an amorphous white portion and a circular glossy portion are mixed to exhibit a surface appearance scattered on the surface. There is. Further, in Patent Document 2, in the thickness direction cross section of the plating layer, the portion where Al crystals are absent between the interface between the plating layer and the base iron and the plating surface layer is 10 of the width direction length of the cross section. A Zn—Al—Mg-based plated steel sheet having an improved plating appearance by occupying% to 50% is described.
  • the average roughness Ra of the center line of the surface of the plated steel sheet is 0.5 to 1.5 ⁇ m, and the size is 1.27 ⁇ m or more contained per PPI (1 inch (2.54 cm)).
  • Patent Document 4 describes a highly corrosion-resistant hot-dip galvanized steel sheet in which the glossiness of the plating layer is increased as a whole and the appearance uniformity is improved by refining the ternary eutectic structure of Al / MgZn 2 / Zn. Is described. However, a technique for improving the durability and not lowering the corrosion resistance when characters or the like appear on the surface of the plating layer has not been known conventionally.
  • Japanese Patent No. 5043234 Japanese Patent No. 5141899 Japanese Patent No. 360804 International Publication No. 2013/002358
  • the present invention has been made in view of the above circumstances, and provides a hot-dip galvanized steel sheet capable of displaying characters, designs, etc. on the surface of a plating layer, having excellent durability thereof, and also having excellent corrosion resistance. That is the issue.
  • the gist of the present invention is as follows. [1] A steel plate and a hot-dip galvanized layer formed on the surface of the steel plate are provided.
  • the hot-dip plating layer is In average composition, Al: 4% by mass or more and less than 25% by mass, Mg: 0% by mass or more and less than 10% by mass, and the balance contains Zn and impurities.
  • the metal structure includes [Al phase] and [ternary eutectic structure of Al / Zn / MgZn 2].
  • the hot-dip galvanized layer includes a first region and a second region. The first region and the second region satisfy either one of the following (a) or (b).
  • the first region is a region in which the average length of the [Al phase] on the surface of the hot-dip plating layer is 200 ⁇ m or more, and the second region is the [Al phase] on the surface of the hot-dip plating layer. ] Is a region where the average length is less than 200 ⁇ m.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer is the length of the boundary.
  • the region is more than 0.3 with respect to L, and in the second region, the [ ternary eutectic structure of Al / Zn / MgZn 2 ] is the same as that of the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer.
  • the opposite length Le is a region of 0.3 or less with respect to the boundary length L.
  • the first region or the second region has a shape obtained by any one of a straight line portion, a curved portion, a figure, a number, a symbol, a pattern or a character, or a combination of two or more of them.
  • the hot-dip galvanized layer further contains 0.0001 to 2% by mass of any one or more of Ni, Ti, Zr, and Sr in total in an average composition [1] to [1] to [ 5]
  • the hot-dip galvanized layer further has an average composition of any one of Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, and C.
  • the numerical range represented by using “-” means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
  • the Zn—Al—Mg-based hot-dip galvanized steel sheet of the present embodiment includes a steel sheet and a hot-dip galvanized layer formed on the surface of the steel sheet, and the hot-dip galvanized layer has an average composition of Al: 4% by mass or more and 25% by mass. Less than, Mg: 0% by mass or more and less than 10% by mass, the balance contains Zn and impurities, and the metal structure is [Al phase] and [Al / Zn / MgZn 2 ternary eutectic structure]. Including.
  • the hot-dip galvanized layer includes a first region and a second region, the first region and the second region satisfy either one of the following (a) or (b), and the first region or the second region It is arranged so as to have a predetermined shape.
  • the first region is a region in which the average length of the [Al phase] on the surface of the hot-dip plating layer is 200 ⁇ m or more
  • the second region is a region in which the average length of the [Al phase] on the surface of the hot-dip plating layer is 200 ⁇ m or more. It is a region of less than 200 ⁇ m.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer is 0 with respect to the boundary length L.
  • the region exceeds .3, and the second region is the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer, and the length of the boundary. It is a region of 0.3 or less with respect to L.
  • the first region or the second region is a straight portion, a curved portion, a figure, a number, a symbol, a pattern or a character, or any one of these. It is arranged so as to form a combination of two or more of them.
  • the first region or the second region is intentionally formed.
  • the [Al phase] is a phase that looks like an island with a clear boundary in the base material of [Al / Zn / MgZn 2 ternary eutectic structure], and this is, for example, the three of Al-Zn-Mg. It corresponds to the "Al" phase at high temperature in the original equilibrium diagram (an Al solid solution that dissolves Zn and contains a small amount of Mg), and is distinguished from Al in the ternary eutectic structure.
  • [Al phase] it is referred to as [Al phase].
  • the material of the steel sheet used as the base of the hot-dip plating layer is not particularly limited. Although details will be described later, as the steel sheet, general steel or the like can be used, and Al killed steel or some high alloy steel can also be used. Further, the shape of the steel plate is not particularly limited. By applying the hot-dip galvanizing method described later to the steel sheet, the hot-dip galvanizing layer according to the present embodiment is formed.
  • the hot-dip galvanized layer contains Al: 4% by mass or more and less than 25% by mass, Mg: 0% by mass or more and less than 10% by mass, and Zn and impurities as a balance in the average composition.
  • the hot-dip galvanized layer preferably contains 4 to 22% by mass of Al and 1 to 10% by mass of Mg in an average composition, and is composed of Zn and impurities as the balance.
  • the hot-dip galvanized layer may contain Si: 0.0001 to 2% by mass in average composition.
  • the hot-dip galvanized layer may contain 0.0001 to 2% by mass in total of any one or more of Ni, Ti, Zr, and Sr in an average composition.
  • the hot-dip galvanized layer has an average composition of any one or more of Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, and Hf, and is 0 in total. It may contain .0001 to 2% by mass.
  • Al 4% by mass or more and less than 25% by mass
  • the content of Al in the hot-dip galvanized layer is 4% by mass or more and less than 25% by mass, preferably 4.0% by mass or more and less than 25.0% by mass in the average composition.
  • Al is an element necessary for ensuring corrosion resistance. If the Al content in the hot-dip galvanized layer is less than 4% by mass, the effect of improving the corrosion resistance is insufficient, and the [Al phase] is not sufficiently formed, which is not preferable for ensuring the design. If it is 25% by mass or more, [Al phase] is excessively formed, which is not preferable for ensuring the design.
  • the Al content in the hot-dip galvanized layer may be 5 to 22% by mass, 5.0 to 22.0% by mass, or 5 to 18% by mass from the viewpoint of corrosion resistance. It may be 5.0 to 18.0% by mass, and may be 6 to 16% by mass. It may be 6.0 to 16.0% by mass.
  • Mg 0% by mass or more and less than 10% by mass
  • the content of Mg in the hot-dip galvanized layer may be 0% by mass or more and less than 10% by mass in the average composition, and may be 0% by mass or more and less than 10.0% by mass in the average composition. It is preferably 1% by mass or more and less than 10% by mass, and preferably 1% by mass or more and less than 10.0% by mass.
  • Mg may be added to improve corrosion resistance. When the Mg content in the hot-dip galvanized layer is 1% by mass or more, the effect of improving the corrosion resistance becomes more sufficient, which is preferable.
  • the Mg content in the hot-dip galvanized layer may be 1.5 to 6% by mass, 1.5 to 6.0% by mass, or 2 to 5%. It may be mass%, or may be 2.0 to 5.0 mass%.
  • the hot-dip galvanized layer may contain Si in the range of 0.0001 to 2% by mass, preferably 0.0001 to 2.000% by mass.
  • Si is an element effective for improving the adhesion of the hot-dip galvanized layer. Since the effect of improving the adhesion is exhibited by containing 0.0001% by mass or more of Si in the hot-dip plating layer, it is preferable to contain 0.0001% by mass or more of Si. On the other hand, even if the content exceeds 2% by mass, the effect of improving the plating adhesion is saturated. Therefore, even when the hot-dip galvanizing layer contains Si, the Si content is set to 2% by mass or less.
  • the Si content in the hot-dip plating layer may be 0.0010 to 1% by mass, 0.0010 to 1.000% by mass, or 0.0100 to 0.8% by mass. It may be 0.0100 to 0.800 mass%.
  • the hot-dip galvanized layer may contain one or more of Ni, Ti, Zr, and Sr in total in an average composition of 0.0001 to 2% by mass, preferably 0.0001 to 0.0001. It may contain 2.00% by mass.
  • the intermetallic compound containing these elements acts as a crystallizing nucleus of the [Al phase] to make the [Al / MgZn 2 / Zn ternary eutectic structure] finer and more uniform, and to improve the appearance of the hot-dip plating layer. Improves smoothness. If the content of these elements in the hot-dip galvanized layer is less than 0.0001% by mass, the effect of making the solidified structure finely uniform becomes insufficient, which is not preferable.
  • the content of these elements in the hot-dip galvanized layer exceeds 2% by mass, the effect of refining the [ternary eutectic structure of Al / MgZn 2 / Zn] is saturated, and the surface of the hot-dip galvanized layer is saturated. It is not preferable because the roughness becomes large and the appearance becomes poor.
  • the content of the above-mentioned elements is preferably 0.001 to 0.5% by mass, preferably 0.001 to 0.50% by mass, and 0. It is more preferably 0.001 to 0.05% by mass, and even more preferably 0.002 to 0.01% by mass.
  • one or more of Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, and Hf are contained in a total of 0. It may contain 0001 to 2% by mass, preferably 0.0001 to 2.00% by mass. When the hot-dip galvanized layer contains these elements, the corrosion resistance can be further improved.
  • REM refers to one or more rare earth elements having atomic numbers 57 to 71 in the periodic table.
  • the rest of the chemical composition of the hot-dip galvanized layer is zinc and impurities.
  • Impurities include those that are inevitably contained in zinc and other bullions, and those that are contained by melting steel in a plating bath.
  • Fe derived from the alloy layer generated at the interface between the plating layer and the steel when the plating is melted may be measured.
  • the average composition of the hot-dip galvanized layer can be measured by the following method. First, the surface coating film is removed with a coating film release agent that does not erode the plating (for example, Neo River SP-751 manufactured by Sansai Kako Co., Ltd.), and then a hot-dip plating layer is used with hydrochloric acid containing an inhibitor (for example, Hiviron manufactured by Sugimura Chemical Industrial Co., Ltd.). Can be determined by dissolving the solution and subjecting the obtained solution to inductively coupled plasma (ICP) emission spectroscopic analysis. The concentration of hydrochloric acid may be, for example, 10% by mass. Further, when the surface layer coating film is not provided, the work of removing the surface layer coating film can be omitted.
  • a coating film release agent that does not erode the plating
  • hydrochloric acid containing an inhibitor for example, Hiviron manufactured by Sugimura Chemical Industrial Co., Ltd.
  • the hot-dip galvanized layer according to the present embodiment contains [Al phase] and [ternary eutectic structure of Al / Zn / MgZn 2] as a metal structure.
  • the hot-dip galvanized layer according to the present embodiment has a form in which [Al phase] is included in the base material of [Al / Zn / MgZn 2 ternary eutectic structure].
  • [MgZn 2 phase] and [Zn phase] may be contained in the base material of [Al / Zn / MgZn 2 ternary eutectic structure].
  • Si when Si is added , [Mg 2 Si phase] may be contained in the base material of [Al / Zn / MgZn 2 ternary eutectic structure].
  • the [ternary eutectic structure of Al / Zn / MgZn 2 ] is a ternary eutectic structure of the Al phase, the Zn phase and the metal compound MgZn 2 phase, and is [Al / Zn / MgZn 2].
  • the Al phase forming the ternary eutectic structure] is, for example, the "Al" phase at high temperature in the ternary system equilibrium diagram of Al-Zn-Mg (Al solid solution that solid-dissolves Zn, and a small amount. Corresponds to (including Mg).
  • the Al ′′ phase at high temperature usually appears as a fine Al phase and a fine Zn phase at room temperature.
  • the Zn phase in [Al / Zn / MgZn 2 ternary eutectic structure] is small. It is a Zn solid solution in which Al is solid-dissolved and, in some cases, a smaller amount of Mg is solid-dissolved.
  • the MgZn two- phase in [Al / Zn / MgZn 2 ternary eutectic structure] is a Zn—Mg binary system.
  • Zn An intermetallic compound phase existing in the vicinity of about 84% by mass in the equilibrium state diagram.
  • phase diagram As far as the phase diagram is concerned, it is considered that other additive elements are not solid-solved in each phase, or even if they are solid-solved, the amount is extremely small. However, since the amount cannot be clearly distinguished by ordinary analysis, the ternary eutectic structure consisting of these three phases is referred to as [Al / Zn / MgZn 2 ternary eutectic structure] in the present specification.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer is the length Le, and the length of the boundary in the first region.
  • the region may be more than 0.3 with respect to the L, and may be 0.3 or less with respect to the boundary length L in the second region.
  • the [Al phase] is a phase that looks like an island with a clear boundary in the base solution of [Al / Zn / MgZn 2 ternary eutectic structure], and this is, for example, a ternary equilibrium of Al—Zn—Mg. It corresponds to the "Al" phase at high temperature in the phase diagram (an Al solid solution that dissolves Zn and contains a small amount of Mg). The amount of Zn and Mg that dissolves in the Al "phase at high temperature differs depending on the concentration of Al and Mg in the plating bath.
  • the Al" phase at high temperature is usually a fine Al phase at room temperature.
  • the island-like shape seen at room temperature is considered to be due to the shape of the Al ′′ phase at high temperature.
  • the phase diagram is concerned, it is considered that other additive elements are not solid-solved in this phase, or even if they are solid-solved, the amount is extremely small.
  • the phase derived from the Al ′′ phase at high temperature and morphologically derived from the shape of the Al ′′ phase is referred to as [Al phase] in the present specification.
  • the [Al phase] can be clearly distinguished from the Al phase forming [Al / Zn / MgZn 2 ternary eutectic structure] by microscopic observation.
  • the average length of the [Al phase] is set to 200 ⁇ m or more in the first region and the second region. Then, it may be less than 200 ⁇ m.
  • the [Zn phase] is a phase that looks like an island with a clear boundary in the substrate of [Al / Zn / MgZn 2 ternary eutectic structure], and actually dissolves a small amount of Al and a small amount of Mg in a solid solution. I have something to do. As far as the phase diagram is concerned, it is considered that other additive elements are not solid-solved in this phase, or even if they are solid-solved, the amount is extremely small.
  • the [Zn phase] can be clearly distinguished from the Zn phase forming [Al / Zn / MgZn 2 ternary eutectic structure] by microscopic observation.
  • the hot-dip galvanized layer according to the present embodiment may contain a [Zn phase] depending on the production conditions, but the effect on the corrosion resistance due to the [Zn phase] was hardly observed. Therefore, even if the hot-dip plating layer contains [Zn phase], there is no particular problem.
  • [MgZn 2- phase] is a phase that looks like an island with a clear boundary in the base material of [Al / Zn / MgZn 2 ternary eutectic structure], and is actually a solid solution of a small amount of Al. Sometimes. As far as the phase diagram is concerned, it is considered that other additive elements are not solid-solved in this phase, or even if they are solid-solved, the amount is extremely small.
  • the [MgZn 2 phase] and [Al / Zn / MgZn 2 ternary eutectic structure] is formed by being MgZn 2 phase, it can be clearly distinguished in microscopic observation.
  • the hot-dip galvanized layer according to the present embodiment may not contain [MgZn 2- phase] depending on the manufacturing conditions, but is contained in the hot-dip galvanized layer under most manufacturing conditions.
  • [Mg 2 Si phase] is a phase that looks like an island with a clear boundary in the solidified structure of the Si-added plating layer. As far as the phase diagram is concerned, it is considered that Zn, Al and other additive elements are not solid-solved in [Mg 2 Si phase], or even if they are solid-solved, they are in a very small amount. [Mg 2 Si phase] can be clearly distinguished from other phases in the hot-dip galvanized layer by microscopic observation.
  • the hot-dip galvanized layer of the present embodiment is formed by immersing the steel sheet in a plating bath and then pulling it up, and then solidifying the molten metal adhering to the surface of the steel sheet.
  • the [Al phase] is first formed, and then the [ternary eutectic structure of Al / Zn / MgZn 2] is formed as the temperature of the molten metal decreases.
  • Chemical components of the molten plating layer i.e., the chemical composition of the plating bath
  • may be, in the matrix of [Al / Zn / MgZn 2 ternary eutectic structure], [Mg 2 Si phase], [MgZn 2 phase] or [Zn phase] may be formed.
  • the hot-dip galvanized layer (surface of the hot-dip galvanized layer) according to the present embodiment has a first region and a second region. As will be described later, the first region and the second region can be distinguished with the naked eye, under a magnifying glass, or under a microscope.
  • the first region may represent a straight portion, a curved portion, or the like
  • the second region may represent a straight portion, a curved portion, or the like.
  • the first region can be arranged so as to have a predetermined shape
  • the other regions can be designated as the second region.
  • the second region represents a straight line portion, a curved portion, or the like
  • the second region can be arranged so as to have a predetermined shape
  • the other region can be the first region.
  • the boundary between the first region and the second region can be grasped with the naked eye, under a magnifying glass or under a microscope.
  • the first region When the first region is arranged so as to have a predetermined shape, the first region may be formed to a size that allows the existence of the first region to be discriminated with the naked eye, under a magnifying glass, or under a microscope.
  • the second region is a region other than the first region in the hot-dip plating layer (surface of the hot-dip plating layer), and may occupy most of the hot-dip plating layer.
  • the first region may be arranged in the second region.
  • the first region is a shape in which one of a straight line portion, a curved portion, a figure, a number, a symbol, a pattern and a character, or a combination of two or more of them is used in the second region.
  • the surface of the hot-dip galvanized layer is formed by any one of straight lines, curved lines, figures, numbers, symbols, patterns and letters, or a combination of two or more of them. Is revealed.
  • This shape is an artificially formed shape, not a naturally formed one.
  • the second region when the second region is arranged so as to have a predetermined shape, the second region is formed to a size that allows the existence of the second region to be discriminated with the naked eye, under a magnifying glass, or under a microscope. Good.
  • the first region is a region other than the second region in the hot-dip plating layer (the surface of the hot-dip plating layer), and may occupy most of the hot-dip plating layer.
  • the second region may be arranged in the first region.
  • the second region is a shape in which one of a straight line portion, a curved portion, a figure, a number, a symbol, a pattern and a character, or a combination of two or more of them is used in the first region.
  • the surface of the hot-dip galvanized layer is formed by any one of straight lines, curved lines, figures, numbers, symbols, patterns and letters, or a combination of two or more of them. Is revealed.
  • This shape is an artificially formed shape, not a naturally formed one.
  • the first region and the second region are not limited to the naked eye, and may be distinguishable under a magnifying glass or a microscope. Specifically, the shape of the straight portion or the like composed of the first region or the second region may be identifiable in a field of view of 50 times or less. If the field of view is 50 times or less, the predetermined shape composed of the first region or the second region can be identified by the difference in the surface state.
  • the first region or the second region can be identified preferably 20 times or less, more preferably 10 times or less, and more preferably 5 times or less.
  • the first region and the second region satisfy either (a) or (b) below.
  • the first region is a region in which the average length of the [Al phase] on the surface of the hot-dip plating layer is 200 ⁇ m or more
  • the second region is a region in which the average length of the [Al phase] on the surface of the hot-dip plating layer is 200 ⁇ m or more. It is a region of less than 200 ⁇ m.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer is 0 with respect to the boundary length L.
  • the region exceeds .3, and the second region is the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer, and the length of the boundary. It is a region of 0.3 or less with respect to L.
  • the case (a) and the case (b) will be described in order.
  • At least [Al phase] and [ ternary eutectic structure of Al / Zn / MgZn 2 ] are present in the hot-dip galvanized layer.
  • the hot-dip galvanized layer has a form in which [Al phase] is included in the base material of [Al / Zn / MgZn 2 ternary eutectic structure].
  • the [Al phase] is precipitated relatively early when the hot-dip plating layer is solidified, and the morphology of the [Al phase] at that time is dendritic.
  • the average length of the [Al phase] existing in the first region is 200 ⁇ m or more.
  • the average length of the [Al phase] is 200 ⁇ m or more, relatively large dendritic crystals of the [Al phase] are exposed on the surface of the hot-dip galvanized layer, and the surrounding [Al / Zn / MgZn 2 ternary elements] are exposed.
  • the [Al phase] which has a metallic luster, is longer than that of the [eutectic structure], and the unevenness becomes clear, so that it can be visually recognized linearly as a whole.
  • the average length of the [Al phase] existing in the second region is less than 200 ⁇ m.
  • the average length of the [Al phase] is less than 200 ⁇ m, relatively small dendritic crystals of the [Al phase] are exposed on the surface of the hot-dip galvanized layer, and the surrounding [Al / Zn / MgZn 2 ternary elements] are exposed. Since the [Al phase], which has a metallic luster, is shorter than that of the [eutectic structure] and the unevenness is unclear, it can be visually recognized as dots as a whole.
  • the second region is preferably a region in which the average length of the [Al phase] is 180 ⁇ m or less, and more preferably a region in which the average length of the [Al phase] is less than 150 ⁇ m.
  • the first region is formed by the formation of the [Al phase] at a relatively low number density at the initial stage of solidification of the hot-dip plating layer and the coarsening of the [Al phase] itself.
  • the second region is formed by forming the [Al phase] at a relatively high number density at the initial stage of solidification of the hot-dip plating layer, and the [Al phase] itself does not become coarse and remains fine. It is presumed to be.
  • the cooling rate of the molten metal may be controlled when the hot-dip plating layer is solidified. Specifically, when the [Al phase] is coarsened, the cooling rate during solidification should be slowed down, and when the [Al phase] is miniaturized, the cooling rate during solidification should be increased.
  • the cooling rate of the molten metal on the surface of the steel sheet is partially increased or decreased, so that straight parts, curved parts, figures, numbers, symbols, patterns and A shape obtained by combining any one of the characters or two or more of them can be intentionally or artificially expressed by a manufacturing method described later.
  • the average length of the [Al phase] is measured by the following method. First, on each of the first region and the second region of the surface of the hot-dip galvanized layer, regions of arbitrary three fields of view are photographed with a reflected electron image of a scanning electron microscope. The size of each region is a rectangular region of 500 ⁇ m ⁇ 360 ⁇ m. In the photograph taken, the dendritic Al phase is confirmed. As shown in FIG. 1, the dendritic Al phase generally has a shape having a main shaft portion and a secondary arm portion extending from the main shaft portion. For the Al phase in the photograph, the length A in the longitudinal direction is measured.
  • the lengths A of all Al phases are obtained in the three fields of view, and the average value thereof is taken as the average length of the Al phases in the first region or the second region.
  • the dendritic Al phase often grows radially from the solidified nucleus, but it is not always arranged in the same plane, and when observing from the surface, only a part thereof, for example, the tip of the secondary arm is observed. Or, only the spindle may be observed. Such Al phase is excluded from the measurement target. On the other hand, those that can be observed as if another phase overlaps between the main shaft and the secondary arm and are not connected are targeted.
  • the first region and the second region satisfy the above (b)
  • the first region has a low metallic luster on the surface thereof and is relatively white or gray as compared with the second region.
  • the second region is a region in which the metallic luster of the surface thereof is relatively higher than that of the first region. This makes the first and second regions distinguishable with the naked eye, under a magnifying glass or under a microscope.
  • At least [Al phase] and [ ternary eutectic structure of Al / Zn / MgZn 2 ] are present in the hot-dip galvanized layer.
  • the hot-dip galvanized layer has a form in which [Al phase] is included in the base material of [Al / Zn / MgZn 2 ternary eutectic structure].
  • the [Al phase] is precipitated relatively early when the hot-dip plating layer is solidified, and the morphology of the [Al phase] at that time is dendritic.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer is the boundary length. It is a region of more than 0.3, preferably more than 0.30 with respect to L.
  • [Al / Zn / MgZn 2 ternary eutectic structure] is relatively abundant on the steel sheet side in the thickness direction of the hot-dip galvanized layer in the first region, and [Al phase] and other phases or structures are present. Relatively less.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer is preferably 0.30 with respect to the boundary length L. It's super. That is, Le / L in the first region is preferably more than 0.30.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer is 0. It is a region of 3 or less, more preferably 0.30 or less.
  • [Al / Zn / MgZn 2 ternary eutectic structure] is relatively small on the steel sheet side in the thickness direction of the hot-dip galvanized layer in the second region, and [Al phase] and other phases or structures are present. It will be relatively large.
  • relatively few dendritic [Al phases] are present on the surface side of the hot-dip galvanized layer in the thickness direction. Therefore, it is presumed that the surface roughness Ra of the surface of the second region is relatively small, and that the second region exhibits a metallic luster relatively as compared with the first region.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer is preferably 0.30 with respect to the boundary length L.
  • the region is as follows, more preferably 0.15 or less, still more preferably 0.1 or less, and particularly preferably 0.10 or less. The larger the difference between Le / L in the first region and Le / L in the second region, the easier it is to distinguish between the first region and the second region, which is preferable.
  • the [Al phase] generated during solidification of the hot-dip galvanized layer is usually deposited in the entire thickness direction of the hot-dip galvanized layer.
  • the surface of the hot-dip galvanized layer is formed by intentionally or artificially controlling the length Le of the [Al / Zn / MgZn 2 ternary eutectic structure] facing the steel sheet at the boundary between the steel sheet and the hot-dip galvanized layer.
  • the first surface of the hot-dip galvanized layer is Regions and second regions can be formed.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the interface between the steel sheet and the hot-dip galvanized layer is 0 with respect to the interface length L.
  • the region may be more than .3.
  • the length Le at which the [ternary eutectic structure of Al / Zn / MgZn 2 ] faces the steel sheet at the interface between the steel sheet and the hot-dip galvanized layer is 0.
  • the area may be 3 or less.
  • the ratio of the length Le in which the [ternary eutectic structure of Al / Zn / MgZn 2] faces the steel sheet with respect to the length L of the boundary (interface) is as follows. It can be measured by such a method. First, the cross section of the Zn—Al—Mg-based hot-dip galvanized steel sheet in the plate thickness direction is exposed. There are five cross sections for each of the first region and the second region. Each cross section is photographed with a scanning electron microscope. In each cross section, a region having a length of 150 ⁇ m is arbitrarily selected from the boundary (interface) between the steel plate and the hot-dip galvanized layer.
  • This length is defined as the boundary length L (interface length L).
  • the [ternary eutectic structure of Al / Zn / MgZn 2 ] is confirmed in the range of the selected boundary (interface) length, and all [Al / Zn / at the boundary (interface) between the steel sheet and the hot-dip galvanized layer).
  • the total length Le of MgZn 2 ternary eutectic structure] is measured to determine Le / L.
  • Le / L was obtained from each of the five cross sections of the first region and the second region, and the average thereof was [Al / Zn] with respect to the length L of the boundary (interface) at the boundary (interface) between the steel sheet and the hot-dip galvanized layer.
  • / MgZn 2 ternary eutectic structure] is the ratio of the length Le facing the steel sheet.
  • the [Al phase] generated during solidification of the hot-dip galvanized layer is usually deposited in the entire thickness direction of the hot-dip galvanized layer.
  • a substance that becomes a solidified nucleus is arranged in advance on the surface of the steel sheet, in the region where the solidified nucleus is arranged, when the molten metal adhering to the surface of the steel sheet solidifies, the solidified nucleus on the surface of the steel sheet becomes a nucleus and a large number of Al phase] precipitates.
  • the generated [Al phase] segregates on the side relatively close to the steel sheet.
  • the [Al phase] is generated at a relatively high density, so that the [Al phase] itself does not become coarse and remains fine. Therefore, in the region where the solidified nuclei are arranged, the [Al phase] does not grow to the surface side of the hot-dip galvanized layer, and a large amount of the [Al phase] is deposited near the boundary (interface) between the steel sheet and the hot-dip galvanized layer.
  • the region where the solidified nuclei are present on the surface of the steel sheet is the second region of the hot-dip galvanized layer, and the region where the solidified nuclei are not present is the first region of the hot-dip galvanized layer. Further, since the second region is formed by the mechanism as described above, solidified nuclei may be present at the boundary (interface) between the steel plate and the hot-dip galvanized layer in the second region.
  • carbon C
  • nickel Ni
  • calcium Ca
  • boron B
  • phosphorus P
  • titanium One or more of the elements selected from the group consisting of Ti
  • manganese Mn
  • iron Fe
  • cobalt Co
  • zirconium Zr
  • molybdenum Mo
  • tungsten W
  • a steel sheet in the second region is used while digging a sample by sputtering using a glow discharge emission spectrophotometer (GDS). It can be confirmed by performing elemental analysis at the boundary between the and the hot-dip plating layer.
  • GDS glow discharge emission spectrophotometer
  • the shape of the surface of the steel sheet is one of straight parts, curved parts, figures, numbers, symbols and letters, or a combination of two or more of them.
  • the area excluding the shape obtained by combining one of straight lines, curved lines, figures, numbers, symbols and letters or two or more of these on the surface of the steel sheet.
  • I (200) / I (111) is preferably 0.8 or more, and more preferably 0.80 or more.
  • the ratio I (200) / I (111) is preferably 0.8 or more, more preferably 0.80 or more, regardless of the first region and the second region.
  • the second region is the opposite.
  • the metallic luster is further emphasized for the above reason, so that the first region and the second region can be distinguished more clearly.
  • the ratio I (200) / I (111) on the surface of the hot-dip galvanized layer can be controlled by adjusting the cooling rate after the plating layer is formed.
  • the Zn—Al—Mg-based hot-dip galvanized steel sheet according to the present embodiment may have a chemical conversion treatment film layer or a coating film layer on the surface of the hot-dip galvanized layer.
  • the type of the chemical conversion-treated film layer or the coating film layer is not particularly limited, and a known chemical conversion-treated film layer or coating film layer can be used.
  • a hot-rolled steel sheet is manufactured, and if necessary, hot-rolled sheet is annealed. After pickling, cold rolling is performed to obtain a cold rolled plate. After degreasing and washing the cold-rolled plate with water, it is annealed (annealed by cold-rolled plate), and the cold-rolled plate after annealing is immersed in a hot-dip galvanizing bath to form a hot-dip plating layer.
  • the hot-dip galvanizing method may be a continuous hot-dip galvanizing method in which a steel sheet is continuously passed through a hot-dip galvanizing bath. But it may be.
  • the hot-dip galvanizing bath preferably contains Al: 4% by mass or more and less than 25% by mass, Mg: 0% by mass or more and less than 10% by mass, and Zn and impurities as the balance. Further, the hot-dip galvanizing bath may contain Al: 4 to 22% by mass and Mg: 1 to 10% by mass, and the balance may contain Zn and impurities. Further, the hot-dip galvanizing bath may contain Si: 0.0001 to 2% by mass. Furthermore, the hot-dip galvanizing bath is any one or 2 of Ni, Ti, Zr, Sr, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, and Hf. A total of 0.001 to 2% by mass of seeds or more may be contained. The average composition of the hot-dip galvanized layer of the present embodiment is almost the same as the composition of the hot-dip galvanized bath.
  • the temperature of the hot-dip galvanizing bath varies depending on the composition, but is preferably in the range of 400 to 500 ° C., for example. This is because if the temperature of the hot-dip galvanizing bath is within this range, a desired hot-dip galvanizing layer can be formed. Further, the amount of adhesion of the hot-dip galvanized layer may be adjusted by means such as gas wiping with respect to the steel sheet pulled up from the hot-dip galvanized bath. The amount of adhesion of the hot-dip plating layer is preferably adjusted so that the total amount of adhesion on both sides of the steel sheet is in the range of 30 to 600 g / m 2.
  • the adhesion amount is less than 30 g / m 2 , the corrosion resistance of the hot-dip galvanized steel sheet is lowered, which is not preferable. If the amount of adhesion exceeds 600 g / m 2, the molten metal adhering to the steel sheet will hang down and the surface of the hot-dip plating layer cannot be smoothed, which is not preferable.
  • the entire steel sheet is cooled and the non-oxidizing gas with respect to the molten metal. Is locally sprayed by a gas nozzle.
  • a non-oxidizing gas such as nitrogen or argon.
  • the average cooling rate between the bath temperature and 345 ° C. is set to 10 ° C./sec for almost the entire hot-dip galvanized layer for the formation of the second region. Cool with the above. Further, for the formation of the first region, the average cooling rate between the bath temperature and 345 ° C. is cooled to a part of the hot-dip galvanized layer at a rate slower than that of the second region, which is less than 8 ° C./sec. ..
  • blast cooling or mist cooling is performed on almost the entire hot-dip galvanized layer for the formation of the second region while keeping the average cooling rate between the bath temperature and 345 ° C. at 15 ° C./sec or higher.
  • a part of the hot-dip galvanized layer is allowed to cool (leave) without cooling for the formation of the first region, or a relatively high temperature non-oxidizing gas is sprayed from the bath temperature to 345 ° C.
  • the average cooling rate during that period shall be 5 ° C./sec or less.
  • the temperature of the non-oxidizing gas in this case may be, for example, in the range of 100 to 300 ° C. However, the temperature of the non-oxidizing gas need not be limited as long as the above average cooling rate can be satisfied.
  • the average cooling rate between the bath temperature and 345 ° C. is set to 8 ° C. with respect to almost the entire hot-dip galvanized layer. Cool at / sec or less. Further, for the formation of the second region, the average cooling rate between the bath temperature and 345 ° C. is cooled to a part of the hot-dip galvanized layer at 10 ° C./sec or more, which is faster than the first region. ..
  • the entire hot-dip galvanized layer is allowed to cool so that the average cooling rate between the bath temperature and 345 ° C. is 5 ° C./sec or less, while the formation of the second region is performed. Therefore, by spraying a relatively low temperature non-oxidizing gas onto a part of the hot-dip galvanized layer, the average cooling rate between the bath temperature and 345 ° C. is set to 15 ° C./sec or more. Cooling of the first region may be performed in an atmosphere of 50 to 150 ° C. in order to reduce the cooling rate.
  • the temperature of the non-oxidizing gas when cooling the second region may be, for example, in the range of 10 to 30 ° C., or may be a mist gas containing water droplets.
  • the ambient temperature and the temperature of the non-oxidizing gas at the time of cooling the first region need not be limited.
  • a hot-rolled steel sheet is manufactured, and if necessary, hot-rolled sheet is annealed. After pickling, cold rolling is performed to obtain a cold rolled plate. After degreasing and washing the cold-rolled plate with water, it is annealed (annealed by cold-rolled plate), and the cold-rolled plate after annealing is immersed in a hot-dip galvanizing bath to form a hot-dip plating layer.
  • solidified nuclei are attached to the surface of the steel sheet, and any one of straight parts, curved parts, figures, numbers, symbols and letters, or any of these, is attached.
  • a pattern portion having a shape in which two or more of the above are combined is formed. Adhesion of solidified nuclei occurs either between cold rolling and cold-rolled sheet annealing, between cold-rolled sheet annealing and immersion in a hot-dip galvanizing bath, or just prior to the final annealing of cold-rolled sheet annealing. It is good to carry out.
  • the component that forms solidified nuclei (hereinafter, may be referred to as a solidified nuclei-forming component) is not particularly limited as long as it is a component that forms solidified nuclei in the process of solidifying the plating layer.
  • the solidification nucleating component include carbon (C), nickel (Ni), calcium (Ca), boron (B), phosphorus (P), titanium (Ti), manganese (Mn), iron (Fe), and cobalt. Any one or more of the elements selected from the group consisting of (Co), zirconium (Zr), molybdenum (Mo), and tungsten (W), or any one or more of the above-mentioned elements. Examples include compounds containing.
  • the above components may be used in combination of 1 or 2 or more.
  • a method of containing the solidified nucleation component in an alloy foil, resin, surfactant, ink, oil, etc. and adhering to the surface of the steel sheet can be mentioned.
  • These solidified nucleation components may be solids themselves, or may be dissolved or dispersed in water or an organic solvent. Alternatively, it may be contained in the ink as a pigment or a dye.
  • a method of adhering the solidified nuclei to the surface of the steel sheet for example, a method of transferring, applying, or spraying a material containing a solidified nucleation component to the surface of the steel sheet can be exemplified.
  • a foil transfer method using hot stamps and cold stamps for example, a printing method using various plates (gravure printing, flexographic printing, offset printing, silk printing, etc.), an inkjet method, a thermal transfer method using an ink ribbon, etc.
  • a general printing method can be used.
  • An example of a transfer method using an alloy foil is a method in which a heated silicon roll is pressed against the alloy foil to transfer it to the surface of the steel sheet while adhering the alloy foil containing the solidified nucleation component to the surface of the steel sheet.
  • a rubber roll or a rubber stamp is attached to the surface of a steel plate while adhering an ink or a surfactant containing a component that becomes a solidification nucleus to a rubber roll or a rubber stamp having a printing pattern formed on the peripheral surface.
  • a method of pressing to transfer the ink or the surfactant can be mentioned. With this method, the solidified nucleation-forming component can be efficiently adhered to the surface of the steel sheet that is continuously passed through.
  • the amount of coagulated nuclei attached is preferably in the range of, for example, 50 mg / m 2 or more and 5000 mg / m 2 or less. If the adhesion amount is less than 50 mg / m 2 , the first region may not be formed to the extent that it can be discerned with the naked eye, a magnifying glass, or a microscope, which is not preferable. On the other hand, when the adhesion amount exceeds 5000 mg / m 2 , the adhesion of the hot-dip plating layer may decrease, which is not preferable.
  • the hot-dip galvanizing method may be a continuous hot-dip galvanizing method in which a steel sheet is continuously passed through a hot-dip galvanizing bath. But it may be.
  • composition of the hot-dip galvanizing bath, the temperature of the hot-dip galvanizing bath, the adhering amount of the hot-dip plating layer, and the control method of the adhering amount may be the same as the manufacturing method when the first region and the second region satisfy the above (a).
  • the temperature at the time of wiping so that the hot-dip plating layer is still in a molten state after adjusting the adhesion amount. Further, after passing through wiping, rapid cooling is required to generate many Al-phase fine crystals during plating. On the other hand, in order to align the direction of solidification, it is necessary to maintain the solidified state for a certain period of time. Therefore, within 1 second after passing through the wiping, the temperature is cooled to a temperature lower than the temperature at which solidification starts (liquidus line temperature) and higher than the temperature at which the plating completely solidifies (solid phase line temperature). In order to sufficiently precipitate fine crystals, it is desirable to cool the fine crystals to a temperature 20 ° C. or higher lower than the liquidus temperature within 1 second.
  • the temperature is rapidly higher than the temperature at which MgZn 2 phase is precipitated in addition to Al existing on the solid phase line (referred to as MgZn 2 phase precipitation temperature line). It is more desirable to stop cooling. By cooling to a temperature of (MgZn 2- phase precipitation temperature +5) ° C. or higher, only fine crystals of Al are generated, and it becomes easy to align the crystal orientation of Al. After that, in order to grow crystals, it is cooled to 300 ° C. or lower by slow cooling at an average cooling rate of less than 10 ° C./sec.
  • the hot-dip galvanized steel sheet after the hot-dip plating layer is formed is subjected to the chemical conversion treatment.
  • the type of chemical conversion treatment is not particularly limited, and a known chemical conversion treatment can be used.
  • a coating film layer is formed on the surface of the hot-dip plating layer or the surface of the chemical conversion treatment layer, the hot-dip galvanized steel sheet after the hot-dip plating layer is formed or the chemical conversion treatment layer is formed is coated. Perform processing.
  • the type of coating treatment is not particularly limited, and a known coating treatment can be used.
  • the hot-dip galvanized layer includes a first region and a second region, and the first region and the second region are as follows (a). ) Or (b), the first region and the second region can be distinguished. Since the first region and the second region are not formed by printing or painting, the durability is high. Further, since the first region and the second region are not formed by printing or painting, there is no influence on the corrosion resistance of the hot-dip galvanized layer. Further, the first region and the second region are not formed by grinding or the like on the surface of the hot-dip plating layer. Therefore, the hot-dip galvanized steel sheet of the present embodiment has excellent corrosion resistance.
  • the present embodiment it is possible to provide a Zn—Al—Mg-based hot-dip galvanized steel sheet having high durability in the first region or the second region molded into a predetermined shape and having suitable plating characteristics such as corrosion resistance.
  • the first area or the second area can be intentionally or artificially shaped, and any one of straight lines, curved lines, dots, figures, numbers, symbols, patterns or letters, or any of these.
  • the first region or the second region can be arranged so as to form a shape in which two or more of the above are combined.
  • the Zn—Al—Mg-based hot-dip galvanized steel sheet of the present embodiment various designs, trademarks, and other identification marks can be displayed on the surface of the hot-dip galvanized layer without printing or painting. It is possible to improve the distinctiveness of the source and the design. Further, depending on the first region or the second region, information necessary for process control, inventory control, etc. and arbitrary information required by the consumer can be added to the Zn—Al—Mg-based hot-dip galvanized steel sheet. This can contribute to the improvement of the productivity of the Zn—Al—Mg-based hot-dip galvanized steel sheet.
  • Example 1 After degreasing and washing the steel sheet with water, reduction annealing, plating bath immersion, adhesion amount control, and cooling were performed to obtain the No. 1 shown in Tables 2A and 2B.
  • the hot-dip galvanized steel sheets 1-1 to 1-21 were manufactured.
  • nitrogen gas is locally sprayed onto the molten metal by a gas nozzle while cooling the entire steel sheet. It was. After that, it was cooled to completely solidify the molten metal.
  • the blowing range of nitrogen gas was controlled so as to form a grid pattern at intervals of 50 mm.
  • Table 1 shows the cooling conditions.
  • the average cooling rates shown in Table 1 are all average cooling rates between the bath temperature and 345 ° C.
  • Cooling conditions A to C were used to express a grid pattern in the second region, and cooling conditions D were used to express a grid pattern in the first region. Further, the cooling conditions E and F were the patterns of the comparative examples.
  • the entire steel sheet was slowly cooled in an atmosphere of 120 ° C., and nitrogen gas at 30 ° C. was sprayed as a non-oxidizing gas.
  • nitrogen gas at 20 ° C. was sprayed as a non-oxidizing gas while allowing the entire steel sheet to cool.
  • nitrogen gas containing mist was sprayed as a non-oxidizing gas while allowing the entire steel sheet to cool.
  • the entire steel sheet was cooled with a nitrogen gas containing mist, and nitrogen gas at 250 ° C. was sprayed as a non-oxidizing gas.
  • the entire steel sheet was allowed to cool in nitrogen gas at 30 ° C., and nitrogen gas at 30 ° C. was sprayed as a non-oxidizing gas.
  • the entire steel sheet was allowed to cool.
  • a Zn-Al-Mg-based hot-dip galvanized steel sheet was manufactured in the same manner as above. Then, a grid pattern at intervals of 50 mm was printed on the surface of the hot-dip plating layer by an inkjet method. This result is referred to as No. It is shown in Table 2A and Table 2B as 1-22.
  • a Zn-Al-Mg-based hot-dip galvanized steel sheet was manufactured in the same manner as above. Then, the surface of the hot-dip galvanized layer was ground to form a grid pattern at intervals of 50 mm. This result is referred to as No. It is shown in Table 2A and Table 2B as 1-23.
  • the average length of the Al phase in the first region and the second region was determined.
  • the boundary between the first region and the second region was identified by visually observing the surface of the hot-dip galvanized layer.
  • the nitrogen gas spraying range is assumed to be the first region or the second region.
  • the average length of the [Al phase] was measured by the following method. First, on the surface of the hot-dip galvanized layer, in each of the first region and the second region, regions of arbitrary three fields of view were photographed by a reflected electron image of a scanning electron microscope. The size of each region was a rectangular region of 500 ⁇ m ⁇ 360 ⁇ m. In the photograph taken, a dendritic [Al phase] was confirmed. As shown in FIG. 1, the dendritic [Al phase] has a shape having a main shaft portion and a primary arm portion extending from the main shaft portion. For the [Al phase] in the photograph, the length A in the longitudinal direction was measured.
  • the lengths A of all [Al phase] were determined in three fields of view, and the average value was taken as the average length of [Al phase] in the first region or the second region.
  • the dendritic [Al phase] often grows radially from the solidified nucleus, but it is not always arranged in the same plane, and when observing from the surface, only a part thereof, for example, the tip of the arm is observed. Or, only the spindle may be observed. Such [Al phase] was excluded from the measurement targets. On the other hand, the measurement target was one in which another phase overlapped between the spindle and the arm and could be observed as if they were not connected.
  • test plates with a grid pattern in the initial state immediately after production and those in the aged state exposed outdoors for 6 months were visually evaluated based on the following criteria. A to C were accepted in both the initial state and the time-lapse state.
  • the test plate was cut to a size of 150 ⁇ 70 mm, and a corrosion acceleration test CCT conforming to JASO-M609 was tested for 30 cycles, and then the rust generation state was investigated and evaluated based on the following criteria.
  • a to C were accepted.
  • C The appearance of the design is slightly impaired, but the grid pattern and other areas can be visually distinguished.
  • D The appearance quality of the grid pattern and the other areas is significantly deteriorated and cannot be visually distinguished.
  • FIG. 2 No. 1-1 to No.
  • FIG. 2 No.
  • the observation results of the first region of 1-4 with a scanning electron microscope are shown
  • FIG. 3 shows No.
  • the observation results by the scanning electron microscope in the second region of 1-4 are shown.
  • the [Al phase] in the first region shown in FIG. 2 has a larger average length of the [Al phase] than the [Al phase] in the second region shown in FIG. 3, and each exhibits a different appearance. It can be seen that the first region and the second region can be identified.
  • the pattern of 1-22 was thinned by outdoor exposure for 6 months, and the distinctiveness was deteriorated.
  • the plating layer of 1-23 contained [Al phase] and [ternary eutectic structure of Al / Zn / MgZn 2].
  • FIG. 4 shows the surface of a hot-dip galvanized steel sheet representing a character string (alphabet) by spraying nitrogen gas onto the Zn—Al—Mg-based hot-dip galvanized layer.
  • characters and marks can be intentionally displayed on the surface of a hot-dip galvanized steel sheet.
  • Example 2 The steel sheet after cold rolling was degreased and washed with water. Next, an ink containing a solidified nucleation component (fine particles of C or Ni) shown in Table 3 was attached to a rubber plate having a shape in which a grid pattern at intervals of 50 mm was transferred. By pressing this rubber plate against the steel sheet after washing with water, the ink adhered to the surface of the steel sheet. Then, the steel sheet was annealed by cold rolling. The steel sheet after cold-rolled sheet was immersed in a hot-dip galvanizing bath and then pulled up. Then, the amount of adhesion was adjusted by gas wiping, and further cooling was performed.
  • a solidified nucleation component fine particles of C or Ni
  • the cooling after controlling the amount of adhesion was carried out under cooling conditions in which the temperature of the hot-dip galvanized layer 1 second after passing through the gas wiping became the temperature shown in Table 4, and then allowed to cool.
  • the No. 1 shown in Tables 5A and 5B. 2-1 to No. A 2-20 Zn—Al—Mg-based hot-dip galvanized steel sheet was manufactured.
  • the temperature of the steel plate in Table 4 is lower than the temperature at which solidification starts (liquidus temperature) and higher than the temperature at which the plating completely solidifies (solid phase temperature), and preferably (MgZn 2 starts to precipitate).
  • the temperature was in the range of +5) ° C. or higher and lower than (liquidus line temperature -20) ° C.
  • a Zn—Al—Mg-based hot-dip galvanized steel sheet was produced in the same manner as above except that the steel sheet to which the solidified nuclei were not adhered was subjected to a hot-dip galvanizing treatment. This is No. 2-21 are shown in Tables 5A and 5B.
  • a Zn—Al—Mg-based hot-dip galvanized steel sheet was produced in the same manner as above except that the steel sheet to which the solidified nuclei were not adhered was subjected to a hot-dip galvanizing treatment.
  • a grid pattern at intervals of 50 mm was printed on the surface of the hot-dip galvanized layer of this steel sheet by an inkjet method. In this way, No. A 2-22 Zn—Al—Mg-based hot-dip galvanized steel sheet was manufactured.
  • a Zn—Al—Mg-based hot-dip galvanized steel sheet was produced in the same manner as above except that the steel sheet to which the solidified nuclei were not adhered was subjected to a hot-dip galvanizing treatment. Then, the surface of the hot-dip galvanized layer was ground to form a grid pattern at intervals of 50 mm. In this way, No. A 2-23 Zn—Al—Mg-based hot-dip galvanized steel sheet was manufactured.
  • the ratio of the length Le of the ternary eutectic structure facing the steel sheet to the boundary length L at the boundary between the steel sheet and the hot-dip galvanized layer in the first region and the second region was determined. ..
  • the boundary between the first region and the second region was identified by visually observing the surface of the hot-dip galvanized layer. In the case where the boundary is difficult to distinguish, the adhesion range of the solidified nucleus is assumed to be the second region.
  • the ratio of the length Le of the ternary eutectic structure to the length L of the boundary facing the steel sheet was measured by the following method.
  • the ratio I (200) / of the X-ray diffraction intensity I (200) of the (200) plane and the X-ray diffraction intensity I (111) of the (111) plane of the Al phase. I (111) was calculated.
  • the X-ray diffraction intensity I (200) on the (200) plane and the X-ray diffraction intensity I (111) on the (111) plane of the Al phase are obtained on the surface of the hot-dip galvanized layer. The measurement was performed, and the ratio I (200) / I (111) was determined.
  • the peak intensity of the (200) plane of the Al phase was defined as the intensity of the (200) plane diffraction peak of Al appearing at 44.74 ° in the 2 ⁇ range.
  • the peak intensity of the (111) plane of the Al phase was defined as the intensity of the (111) plane diffraction peak of Al appearing in the range of 38.47 in the 2 ⁇ range.
  • an X-ray diffractometer for measuring a minute region was used. The step was 0.02 °, the scanning speed was 5 ° / min, and a high-speed semiconductor two-dimensional detector was used as the detector.
  • the X-rays emitted from the X-ray light source were focused by the polycapillaries.
  • the X-ray irradiation range after condensing was a circle with a diameter of 1 mm.
  • test plates with a grid pattern in the initial state immediately after production and those in the aged state exposed outdoors for 6 months were visually evaluated based on the following criteria. A to C were accepted in both the initial state and the time-lapse state.
  • A The grid pattern can be visually recognized even from 8 m away.
  • B The grid pattern cannot be visually recognized from 8 m ahead, but the visibility is high from 4 m ahead.
  • C The grid pattern cannot be visually recognized from 4 m ahead, but the visibility is high from 1 m ahead.
  • D The grid pattern cannot be visually recognized from 1 m ahead.
  • the test plate was cut to a size of 150 ⁇ 70 mm, and a corrosion acceleration test CCT conforming to JASO-M609 was tested for 30 cycles, and then the rust generation state was investigated and evaluated based on the following criteria.
  • a to C were accepted.
  • C The appearance of the design is slightly impaired, but the grid pattern and other areas can be visually distinguished.
  • D The appearance quality of the grid pattern and the other areas is significantly deteriorated and cannot be visually distinguished.
  • No. 1 in which a grid pattern was printed by an inkjet method In 2-22, the pattern was thinned by outdoor exposure for 6 months, and the design was deteriorated. Moreover, since the solidified nucleus was not attached, the second region was not formed. Furthermore, No. 1 in which a grid pattern was formed by grinding. In 2-23, the thickness of the plating layer at the ground portion was reduced, and the corrosion resistance at the ground portion was reduced. Moreover, since the solidified nucleus was not attached, the second region was not formed.
  • the hot-dip galvanized layer of 2-23 contained [Al phase] and [ternary eutectic structure of Al / Zn / MgZn 2].
  • FIG. 7 shows the surface of a hot-dip galvanized steel sheet in which a character string (alphabet) is represented by a second region on a Zn—Al—Mg-based hot-dip galvanized layer.
  • characters and marks can be intentionally displayed on the surface of a hot-dip galvanized steel sheet.
  • various designs, trademarks, and other identification marks can be displayed on the surface of the Zn—Al—Mg-based hot-dip galvanized layer without printing or painting, and the origin of the steel sheet can be identified.
  • the design can be improved.
  • information necessary for process control, inventory control, etc. and arbitrary information required by the consumer can be added to the Zn—Al—Mg-based hot-dip galvanized steel sheet. This can contribute to the improvement of the productivity of the Zn—Al—Mg-based hot-dip galvanized steel sheet. Therefore, it has sufficient industrial applicability.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Thermal Sciences (AREA)
  • Coating With Molten Metal (AREA)
PCT/JP2020/025968 2019-11-29 2020-07-02 Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板 WO2021106260A1 (ja)

Priority Applications (3)

Application Number Priority Date Filing Date Title
KR1020227016563A KR102658299B1 (ko) 2019-11-29 2020-07-02 Zn-Al-Mg계 용융 도금 강판
CN202080080847.9A CN114729437A (zh) 2019-11-29 2020-07-02 Zn-Al-Mg系热浸镀钢板
TW109131294A TWI815038B (zh) 2019-11-29 2020-09-11 Zn-Al-Mg系熔融鍍敷鋼板

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2019-216685 2019-11-29
JP2019216686A JP7381865B2 (ja) 2019-11-29 2019-11-29 Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板
JP2019-216686 2019-11-29
JP2019216685A JP7381864B2 (ja) 2019-11-29 2019-11-29 Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板

Publications (1)

Publication Number Publication Date
WO2021106260A1 true WO2021106260A1 (ja) 2021-06-03

Family

ID=76130481

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2020/025968 WO2021106260A1 (ja) 2019-11-29 2020-07-02 Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板

Country Status (4)

Country Link
KR (1) KR102658299B1 (ko)
CN (1) CN114729437A (ko)
TW (1) TWI815038B (ko)
WO (1) WO2021106260A1 (ko)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117280070A (zh) * 2021-09-07 2023-12-22 日本制铁株式会社 热浸镀钢材

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001262305A (ja) * 2000-03-15 2001-09-26 Sumitomo Metal Ind Ltd 加工性に優れた溶融Ｚｎ−Ａｌ系合金めっき鋼板とその製造方法
JP2003268517A (ja) * 2002-03-08 2003-09-25 Nippon Steel Corp 表面平滑性に優れる溶融めっき鋼材
WO2004038060A1 (ja) * 2002-10-28 2004-05-06 Nippon Steel Corporation 表面平滑性と成形性に優れる高耐食性溶融めっき鋼材と溶融めっき鋼材の製造方法
WO2011001662A1 (ja) * 2009-06-30 2011-01-06 新日本製鐵株式会社 Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板とその製造方法
WO2013002358A1 (ja) * 2011-06-30 2013-01-03 新日鐵住金株式会社 外観均一性に優れた高耐食性溶融亜鉛めっき鋼板およびその製造方法
WO2016162982A1 (ja) * 2015-04-08 2016-10-13 新日鐵住金株式会社 Ｚｎ－Ａｌ－Ｍｇ系めっき鋼板、及びＺｎ－Ａｌ－Ｍｇ系めっき鋼板の製造方法
WO2019221193A1 (ja) * 2018-05-16 2019-11-21 日本製鉄株式会社 めっき鋼材

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5043234U (ko) 1973-08-17 1975-05-01
JPS5346720Y2 (ko) 1974-08-23 1978-11-08
JPS60804B2 (ja) 1975-07-22 1985-01-10 シャープ株式会社 電子時計
KR100491363B1 (ko) * 2003-07-26 2005-05-25 주식회사 그레인 금속 표면에 내부 조직구조 패턴의 발현 디자인 시각화방법 및 그 성형물
CN104630682A (zh) * 2015-01-23 2015-05-20 上海大学 激光热处理细化热浸镀镀层材料的方法
TWI654338B (zh) * 2017-12-28 2019-03-21 日商新日鐵住金股份有限公司 Fused Zn-based plated steel sheet with excellent corrosion resistance after painting

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001262305A (ja) * 2000-03-15 2001-09-26 Sumitomo Metal Ind Ltd 加工性に優れた溶融Ｚｎ−Ａｌ系合金めっき鋼板とその製造方法
JP2003268517A (ja) * 2002-03-08 2003-09-25 Nippon Steel Corp 表面平滑性に優れる溶融めっき鋼材
WO2004038060A1 (ja) * 2002-10-28 2004-05-06 Nippon Steel Corporation 表面平滑性と成形性に優れる高耐食性溶融めっき鋼材と溶融めっき鋼材の製造方法
WO2011001662A1 (ja) * 2009-06-30 2011-01-06 新日本製鐵株式会社 Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板とその製造方法
WO2013002358A1 (ja) * 2011-06-30 2013-01-03 新日鐵住金株式会社 外観均一性に優れた高耐食性溶融亜鉛めっき鋼板およびその製造方法
WO2016162982A1 (ja) * 2015-04-08 2016-10-13 新日鐵住金株式会社 Ｚｎ－Ａｌ－Ｍｇ系めっき鋼板、及びＺｎ－Ａｌ－Ｍｇ系めっき鋼板の製造方法
WO2019221193A1 (ja) * 2018-05-16 2019-11-21 日本製鉄株式会社 めっき鋼材

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117280070A (zh) * 2021-09-07 2023-12-22 日本制铁株式会社 热浸镀钢材
CN117280070B (zh) * 2021-09-07 2024-04-19 日本制铁株式会社 热浸镀钢材

Also Published As

Publication number Publication date
KR20220084142A (ko) 2022-06-21
CN114729437A (zh) 2022-07-08
TW202126834A (zh) 2021-07-16
KR102658299B1 (ko) 2024-04-18
TWI815038B (zh) 2023-09-11

Similar Documents

Publication Publication Date Title
JP6648871B1 (ja) Ｚｎ−Ａｌ−Ｍｇ系溶融めっき鋼板及びその製造方法
JP7381865B2 (ja) Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板
CN110268087B (zh) 镀覆钢材
CA2780445C (en) Hot-dipped steel and method of producing same
KR102384674B1 (ko) 내식성, 내골링성, 가공성 및 표면 품질이 우수한 도금 강판 및 이의 제조방법
CN113994018B (zh) 镀覆钢材
JP7445128B2 (ja) 加工性と耐食性に優れる溶融Ｚｎ－Ａｌ－Ｍｇ系めっき鋼材
JP7381864B2 (ja) Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板
JP7328543B2 (ja) 溶融めっき鋼板
JP7328542B2 (ja) 溶融めっき鋼板
WO2021106260A1 (ja) Ｚｎ－Ａｌ－Ｍｇ系溶融めっき鋼板
WO2021106259A1 (ja) 溶融めっき鋼板
JP7339531B2 (ja) 溶融めっき鋼板
JP7328541B2 (ja) 溶融めっき鋼板
JP7410448B1 (ja) 溶融めっき鋼板
KR101168730B1 (ko) Ｍｇ기 합금 도금 강재
JP2022124269A (ja) 溶融めっき鋼板
TW202405205A (zh) 熔融鍍敷鋼板

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20893775

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 20227016563

Country of ref document: KR

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 20893775

Country of ref document: EP

Kind code of ref document: A1