KR20220084142A - Zn-Al-Mg hot-dip galvanized steel sheet - Google Patents

Abstract

The Zn-Al-Mg-based hot-dip plated steel sheet has, as a metal structure, a hot-dip plated layer comprising [Al phase] and [a ternary eutectic structure of Al/Zn/MgZn ₂ ], and the hot-dip plated layer is ) or (b), the first region and the second region are included, and the first region or the second region is arranged to have a predetermined shape. (a) The first region is a region in which the average length of [Al phase] on the surface of the hot-dip plated layer is 200 µm or more, and the second region has an average length of [Al phase] on the surface of the hot-dip layer that is less than 200 µm is the area (b) the first region is a region in which the length Le in which [the ternary eutectic structure of Al/Zn/MgZn ₂ ] faces the steel plate at the interface between the steel sheet and the hot-dip plated layer is greater than 0.3 with respect to the length L of the interface, The second region is a region in which the length Le in which [the ternary eutectic structure of Al/Zn/MgZn ₂ ] faces the steel plate at the interface between the steel sheet and the hot-dip plated layer is 0.3 or less with respect to the length L of the interface.

Description

Zn-Al-Mg hot-dip galvanized steel sheet

The present invention relates to a Zn-Al-Mg-based hot-dip plated steel sheet.

This application claims priority on November 29, 2019 based on Japanese Patent Application No. 2019-216685 and Japanese Patent Application No. 2019-216686 for which it applied in Japan, The content is used here.

Zn-Al-Mg-based hot-dip galvanized steel sheet, which has higher corrosion resistance than hot-dip galvanized steel sheet, is widely used in various manufacturing industries such as building materials, home appliances, and automobile fields, and its usage is increasing in recent years.

However, for the purpose of displaying characters, patterns, designs, etc. on the surface of the hot-dip plated layer of a hot-dip plated steel sheet, by performing a process such as printing or painting on the hot-dip plated layer, characters, patterns, designs, etc., of the hot-dip plated layer It may appear on the surface.

However, when a process such as printing or painting is performed on the hot-dip plated layer, there is a problem in that the cost and time for performing characters, design, and the like increase. In addition, when characters or designs are displayed on the surface of the plating layer by printing or painting, not only the metallic luster appearance that has been highly supported by consumers is lost, but also the deterioration of the coating film itself over time and the deterioration of the adhesion of the coating film over time. From a viewpoint, durability is inferior, and there exists a possibility that a character, a design, etc. may lose|disappear with time. Moreover, when a character, a design, etc. are shown on the surface of a plating layer by stamping ink, although cost and time are comparatively suppressed, there exists a possibility that the corrosion resistance of a hot-dip plating layer may fall with ink. In addition, in the case of showing design by grinding the hot-dip plated layer, the durability of the design, etc. is excellent, but since the thickness of the hot-dip plated layer at the grinding point is significantly reduced, the corrosion resistance is inevitably reduced, and there is concern about the deterioration of the plating properties. .

As disclosed in the following patent documents, various technologies have been developed for a Zn-Al-Mg-based hot-dip plated steel sheet, but a technique for improving durability when characters or designs are displayed on the surface of the plating layer is not known.

Related to Zn-Al-Mg-based hot-dip galvanized steel sheet, there is a prior art for the purpose of making more beautiful the appearance of plating in a pear-shaped (pear-shell shape) seen in a Zn-Al-Mg-based hot-dip galvanized steel sheet.

For example, Patent Document 1 discloses a Zn-Al-Mg-based hot-dip plated steel sheet having a smooth and smooth appearance with many shiny parts, that is, a large number of white parts per unit area, and the ratio of the area of the shiny part A Zn-Al-Mg-based hot-dip plated steel sheet having a large and good egg-shaped appearance is disclosed. Moreover, in Patent Document 1, it is described that the undesirable state of the eggplant is a state in which an irregular white part and a circular glossy part are mixed to reveal the surface appearance dotted on the surface.

Further, in Patent Document 2, in the cross section in the thickness direction of the plating layer, a portion in which Al crystals are not present between the interface between the plating layer and the base iron and the plating surface layer occupies 10% to 50% of the length in the width direction of the cross section, A Zn-Al-Mg-based plated steel sheet with improved plating appearance is disclosed.

Further, in Patent Document 3, the average roughness Ra of the center line of the surface of the plated steel sheet is 0.5 to 1.5 μm, the PPI (number of peaks having a size of 1.27 μm or more contained per inch (2.54 cm)) is 150 to 300, and Pc (1 A hot-dip galvanized steel sheet excellent in formability is disclosed, in which the number of peaks of a size of 0.5 μm or more included per cm) is Pc≧PPI/2.54+10.

In addition, Patent Document 4 describes a highly corrosion-resistant hot-dip galvanized steel sheet with improved overall appearance uniformity and increased gloss of the plating layer as a whole by refining the ternary eutectic structure of Al/MgZn ₂ /Zn.

However, when a character etc. are shown on the surface of a plating layer, the technique of improving the durability and preventing corrosion resistance from being reduced conventionally has not been known.

Japanese Patent Publication No. 5043234 Japanese Patent No. 5141899 Publication Japanese Patent No. 3600804 Publication International Publication No. 2013/002358

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hot-dip plated steel sheet that can display characters, designs, etc. on the surface of a plating layer, is excellent in their durability, and is also excellent in corrosion resistance.

The gist of the present invention is as follows.

[1] A steel sheet and a hot-dip plated layer formed on the surface of the steel sheet,

The hot-dip plated layer,

As an average composition, Al: 4 mass % or more and less than 25 mass %, Mg: 0 mass % or more and less than 10 mass % are contained, balance contains Zn and an impurity,

The metal structure includes [Al phase] and [a ternary eutectic structure of Al/Zn/MgZn ₂ ];

The hot-dip plated layer includes a first region and a second region,

The first region and the second region satisfy either of the following (a) or (b),

A Zn-Al-Mg-based hot-dip galvanized steel sheet, wherein the first region or the second region is arranged to have a predetermined shape.

(a) The first region is a region in which the average length of the [Al phase] on the surface of the hot-dip plated layer is 200 µm or more, and the second region is the [Al phase] on the surface of the hot-dip plated layer. ] is a region with an average length of less than 200 µm.

(b) in the first region, at the boundary between the steel sheet and the hot-dip plated layer, the length Le in which the [Al/Zn/MgZn ₂ ternary eutectic structure] faces the steel sheet is the length L of the boundary is a region greater than 0.3, and, in the second region, at the boundary between the steel sheet and the hot-dip plated layer, the length Le at which the [Al/Zn/MgZn ₂ ternary eutectic structure] faces the steel sheet is the length of the boundary It is an area|region which is 0.3 or less with respect to L.

[2] In the case where the first region and the second region are the above (b), the X-ray diffraction intensity I (200) of the (200) plane of the [Al phase] on the surface of the hot-dip plated layer The Zn-Al-Mg-based hot-dip galvanized steel sheet according to [1], wherein the ratio I(200)/I(111) of the X-ray diffraction intensity I(111) of the (111) plane is 0.8 or more.

[3] The first region or the second region is arranged so as to have a shape obtained by combining any one of a straight line portion, a curved portion, a figure, a number, a symbol, a pattern, or a letter, or a combination of two or more types thereof; [1] ] or the Zn-Al-Mg-based hot-dip galvanized steel sheet according to [2].

[4] The Zn-Al-Mg-based hot-dip plated steel sheet according to any one of [1] to [3], wherein the first region or the second region is intentionally formed.

[5] The Zn-Al-Mg-based hot-dip plated steel sheet according to any one of [1] to [4], wherein the hot-dip plated layer further contains Si: 0.0001 to 2 mass% as an average composition.

[6] Any one of [1] to [5], wherein the hot-dip plated layer further contains 0.0001 to 2 mass % of Ni, Ti, Zr, and Sr in an average composition of 0.0001 to 2 mass% in total The Zn-Al-Mg-based hot-dip galvanized steel sheet according to claim 1 .

[7] The hot-dip plated layer has an average composition, and any one or two of Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, C The Zn-Al-Mg-based hot-dip plated steel sheet according to any one of [1] to [6], comprising 0.0001 to 2 mass% of the above in total.

[8] The Zn-Al-Mg-based hot-dip plated steel sheet according to any one of [1] to [7], wherein the adhesion amount of the hot-dip plated layer is 30 to 600 g/m 2 in total on both sides of the steel sheet.

ADVANTAGE OF THE INVENTION According to this invention, when a character, a design, etc. are shown on the surface of a hot-dip plated layer, they are excellent in durability and also excellent in corrosion resistance can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the measuring method of the size of Al phase of a Zn-Al-Mg type hot-dip plated steel sheet which is an example of this embodiment.
2 shows No. It is a photograph which shows the observation result by the scanning electron microscope of the 1st area|region of 1-4.
3 shows No. It is a photograph which shows the observation result by the scanning electron microscope of the 2nd area|region of 1-4.
4 is a photograph showing an example of the Zn-Al-Mg-based hot-dip plated steel sheet of Example 1.
5 shows No. It is a cross-sectional photograph by a scanning electron microscope in the 1st area|region of 2-1.
6 shows No. It is a cross-sectional photograph by a scanning electron microscope in the 2nd area|region of 2-1.
7 is a photograph showing an example of the surface of the hot-dip plated layer of the Zn-Al-Mg-based hot-dip plated steel sheet of Example 2, and is a photograph showing a state in which a predetermined pattern is expressed by the second region.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

In addition, in this specification, the numerical range expressed using "to" means the range which includes the numerical value described before and after "to" as a lower limit and an upper limit.

The Zn-Al-Mg-based hot-dip plated steel sheet of this embodiment includes a steel sheet and a hot-dip plated layer formed on the surface of the steel sheet, and the hot-dip plated layer has an average composition of Al: 4% by mass or more and less than 25% by mass, Mg: It contains 0 mass % or more and less than 10 mass %, balance contains Zn and an impurity, and contains [Al phase] and [a ternary eutectic structure of Al/Zn/MgZn ₂ ] as a metal structure. The hot-dip plated layer includes a first region and a second region, the first region and the second region satisfy either of the following (a) or (b), and the first region or the second region is a predetermined arranged to be in shape.

(a) The first region is a region in which the average length of [Al phase] on the surface of the hot-dip plated layer is 200 µm or more, and in the second region, the average length of the [Al phase] on the surface of the hot-dip layer is 200 It is a region smaller than μm.

(b) the first region is a region in which the length Le in which [the ternary eutectic structure of Al/Zn/MgZn ₂ ] faces the steel plate at the boundary between the steel sheet and the hot-dip plated layer is greater than 0.3 with respect to the length L of the boundary, The second region is a region in which the length Le in 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 plated layer is 0.3 or less with respect to the length L of the boundary.

In the Zn-Al-Mg-based hot-dip galvanized steel sheet of the present embodiment, preferably, the first region or the second region is any one or two of a straight line portion, a curved portion, a figure, a number, a symbol, a pattern, or a letter. It is arrange|positioned so that it may become the shape which combined more than a species. The first region or the second region is intentionally formed.

Here, [Al phase] is a phase seen as an island phase as a clear boundary in the substrate of [a ternary eutectic structure of Al/Zn/MgZn ₂ ], which is, for example, a ternary equilibrium of Al-Zn-Mg Corresponds to the "Al"phase" at high temperature in the phase diagram (a solid solution of Al that dissolves Zn and contains a small amount of Mg), and is distinguished from Al in the ternary eutectic structure. Hereinafter, in this embodiment, It is denoted as [Al phase].

<Steel plate>

The material in particular of the steel plate used as a base material of a hot-dip plated layer is not restrict|limited. Although detailed later, as a steel plate, general steel etc. can be used and it is also possible to use Al killed steel and some high alloy steel. Also, the shape of the steel sheet is not particularly limited. The hot-dip plating layer according to the present embodiment is formed by applying the hot-dip plating method described later to the steel sheet.

<Hot dip plating layer>

(chemical composition)

Next, the chemical component of a hot-dip plated layer is demonstrated.

A hot-dip plated layer contains Al: 4 mass % or more and less than 25 mass %, Mg: 0 mass % or more and less than 10 mass % by an average composition, and Zn and an impurity are included as balance. The hot-dip plated layer preferably contains Al: 4 to 22 mass% and Mg: 1 to 10 mass% in an average composition, and the balance consists of Zn and impurities.

A hot-dip layer may contain Si:0.0001-2 mass % by an average composition. A hot-dip plated layer may contain 0.0001-2 mass % of Ni, Ti, Zr, and Sr any 1 type, or 2 or more types in total by an average composition. The hot-dip plated layer has an average composition of Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, or Hf in total of any one or two or more of 0.0001 to 2 You may contain mass %.

[Al: 4% by mass or more and less than 25% by mass]

Content of Al in a hot-dip layer is 4 mass % or more and less than 25 mass % in average composition, Preferably they are 4.0 mass % or more and less than 25.0 mass %. Al is an element necessary in order to ensure corrosion resistance. When the content of Al in the hot-dip plated layer is less than 4% by mass, the effect of improving the corrosion resistance is insufficient, and the [Al phase] is not sufficiently formed, so it is not preferable for securing designability, and when it is 25% by mass or more, Since [Al phase] is formed excessively, it is unpreferable for ensuring designability. Content of Al in a hot-dip layer may be 5-22 mass % from a corrosion-resistant viewpoint, 5.0-22.0 mass % may be sufficient, 5-18 mass % may be sufficient, 5.0-18.0 mass % may be sufficient, and 6-16 mass % may be sufficient. It may be mass %. 6.0 to 16.0 mass % may be sufficient.

[Mg: 0 mass% or more and less than 10 mass%]

Content of Mg in a hot-dipping layer may be 0 mass % or more and less than 10 mass % by an average composition, and 0 mass % or more and less than 10.0 mass % may be sufficient as an average composition. Preferably they are 1 mass % or more and less than 10 mass %, Preferably, 1 mass % or more and less than 10.0 mass % may be sufficient. Mg may be added in order to improve corrosion resistance. Since the effect of improving corrosion resistance becomes more sufficient when content of Mg in a hot-dip plated layer becomes 1 mass % or more, it is preferable. Moreover, when Mg is 10 mass % or more, since Mg compound crystallizes, it is unpreferable for ensuring designability, and dross generation in a plating bath becomes remarkable, and it is preferable because it becomes difficult to manufacture a hot-dip galvanized steel sheet stably. don't From a viewpoint of the balance of corrosion resistance and suppression of dross generation, content of Mg in a hot-dip layer is good also as 1.5-6 mass %, it is good also as 1.5-6.0 mass %, it is good also as 2-5 mass %, 2.0 It is good also as thru|or 5.0 mass %.

A hot-dip plated layer may contain Si in 0.0001-2 mass %, Preferably it is good also as 0.0001-2.000 mass %. Si is an element effective in improving the adhesiveness of a hot-dip plating layer.

Since the effect of improving adhesiveness is expressed by containing 0.0001 mass % or more of Si in a hot-dipping layer, it is preferable to contain 0.0001 mass % or more of Si.

On the other hand, since the effect of improving plating adhesiveness is saturated even if it contains exceeding 2 mass %, even when making a hot-dip layer contain Si, content of Si shall be 2 mass % or less.

From the viewpoint of plating adhesion, the content of Si in the hot-dip plated layer may be 0.0010 to 1 mass%, may be 0.0010 to 1.000 mass%, may be 0.0100 to 0.8 mass%, or may be 0.0100 to 0.800 mass%. .

In a hot-dipping layer, 0.0001-2 mass % of any 1 type, or 2 or more types of Ni, Ti, Zr, and Sr in total may be contained in an average composition, Preferably you may contain 0.0001-2.00 mass %. Intermetallic compounds containing these elements act as crystallization nuclei of [Al phase], make [Al/MgZn ₂ /Zn ternary eutectic structure] more fine and uniform, and improve the appearance and smoothness of the hot-dip plated layer make it If the content of these elements in the hot-dip plated layer is less than 0.0001 mass %, the effect of making the solidified structure fine and uniform becomes insufficient, which is not preferable. Moreover, when the content of these elements in the hot-dip plated layer exceeds 2% by mass, the effect of refining [the ternary eutectic structure of Al/MgZn ₂ /Zn] is saturated, and the surface roughness of the hot-dip plated layer becomes large and the appearance This is undesirable because it deteriorates.

In particular, when adding the above-mentioned element for the purpose of improving the appearance of the hot-dip plated layer, the content of the above-mentioned element is preferably 0.001 to 0.5 mass%, preferably 0.001 to 0.50 mass%, more preferably 0.001 to 0.05 mass%. and more preferably 0.002 to 0.01 mass %.

In the hot-dip plated layer, as an average composition, one or more of Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, and Hf is 0.0001 to 2 mass% in total may contain, Preferably 0.0001-2.00 mass % may be contained. When the hot-dip plated layer contains these elements, corrosion resistance can be further improved.

In addition, REM refers to 1 type, or 2 or more types of rare-earth elements with atomic numbers 57-71 in the periodic table.

The remainder of the chemical component of the hot-dip plated layer is zinc and impurities. Impurities include those that are unavoidably contained in metal other than zinc, and those contained by dissolving steel in a plating bath. Moreover, when dissolving plating, Fe derived from the alloy layer produced|generated at the interface of a plating layer and steel may be measured.

In addition, the average composition of a hot-dip plated layer can be measured by the following method. First, after removing the surface coating film with a coating film release agent that does not corrode the plating (eg, Neoriba SP-751 manufactured by Sansai Chemical Co., Ltd.), an inhibitor (eg, Hivilon manufactured by Sugimura Chemical Co., Ltd.) is added It can be obtained by dissolving the hot-dip plated layer with hydrochloric acid and subjecting the resulting solution to inductively coupled plasma (ICP) emission spectroscopy. The concentration of hydrochloric acid may be, for example, 10% by mass. In addition, when it does not have a surface layer coating film, the removal operation|work of a surface layer coating film can be abbreviate|omitted.

(metallic tissue)

Next, the metal structure of a hot-dip plated layer is demonstrated. The hot-dip plated layer according to the present embodiment includes [Al phase] and [a ternary eutectic structure of Al/Zn/MgZn ₂ ] as metal structures.

Specifically, the hot-dip plated layer according to the present embodiment has a form in which [Al phase] is included in the material of [a ternary eutectic structure of Al/Zn/MgZn ₂ ].

Further, [MgZn ₂ phase] and [Zn phase] may be contained in the material of [the ternary eutectic structure of Al/Zn/MgZn ₂ ].

In addition, when Si is added, [Mg ₂ Si phase] may be contained in the material of [ternary eutectic structure of Al/Zn/MgZn ₂ ].

[Al/Zn/MgZn ₂ ternary eutectic structure]

Here, [ternary eutectic structure of Al/Zn/MgZn ₂ ] is a ternary eutectic structure of Al phase, Zn phase, and intermetallic compound MgZn ₂ phase, and [ternary eutectic structure of Al/Zn/MgZn ₂ ] is The formed Al phase corresponds to, for example, the "Al" phase at high temperature in the ternary equilibrium diagram of Al-Zn-Mg (it is an Al solid solution in which Zn is dissolved, and contains a small amount of Mg).

At room temperature, the Al" phase at this high temperature is usually divided into a fine Al phase and a fine Zn phase. The Zn phase in [Al/Zn/MgZn ₂ ternary eutectic structure] uses a small amount of Al as a solid solution, and in some cases, is a Zn solid solution in which a small amount of Mg is further dissolved in. The MgZn ₂ phase in [Al/Zn/MgZn ₂ ternary eutectic structure] is present in the vicinity of Zn: about 84% by mass in the binary system equilibrium diagram of Zn-Mg. It is an intermetallic compound phase.

As far as the phase diagram is concerned, other additive elements are not dissolved in each phase, or are considered to be in very small amounts even in solid solution. However, since the amount cannot be clearly distinguished in ordinary analysis, the ternary eutectic structure composed of these three phases is expressed as [the ternary eutectic structure of Al/Zn/MgZn ₂ ] in the present specification.

In the present embodiment, as will be described later, at the boundary between the steel sheet and the hot-dip plated layer, the length Le in which [the ternary eutectic structure of Al/Zn/MgZn ₂ ] faces the steel sheet is, and in the first region, the length L of the boundary It is set as the area|region used as more than 0.3, and it is good also as the area|region used as 0.3 or less with respect to the length L of the boundary in a 2nd area|region.

[Al phase]

[Al phase] is a phase seen as an island phase as a clear boundary in the substrate of [a ternary eutectic structure of Al/Zn/MgZn ₂ ], and this is, for example, a high temperature in the ternary equilibrium diagram of Al-Zn-Mg It corresponds to the "Al"phase" (a solid solution of Al in which Zn is dissolved and contains a small amount of Mg). The Al" phase at this high temperature depends on the Al or Mg concentration of the plating bath, the amount of Zn dissolved or The amount of Mg is different. The Al" phase at this high temperature is normally separated into a fine Al phase and a fine Zn phase at normal temperature, but the shape of the island phase seen at room temperature is thought to be due to the shape of the Al" phase at high temperature.

As far as the phase diagram is concerned, other added elements are not dissolved in this phase, or are considered to be in very small amounts even if dissolved. However, since it cannot be clearly distinguished in a normal analysis, the phase derived from the Al" phase at this high temperature and geometrically derived from the shape of the Al" phase is referred to as [Al phase] in this specification.

The [Al phase] can be clearly distinguished from the Al phase forming [the ternary eutectic structure of Al/Zn/MgZn ₂ ] in microscopic observation.

In the present embodiment, as will be described later, when the first region and the second region satisfy the above (a), the average length of the [Al phase] is 200 µm or more in the first region, and the second region It is good also as less than 200 micrometers.

[Zn phase]

[Zn phase] is a phase that appears to be an island phase as a clear boundary among the substrates of [a ternary eutectic structure of Al/Zn/MgZn ₂ ], and in reality, a small amount of Al or a small amount of Mg is dissolved therein in some cases. As far as the phase diagram is concerned, no other additive element is dissolved in this phase, or it is considered to be in a very small amount even if dissolved.

The [Zn phase] can be clearly distinguished from the Zn phase forming [the ternary eutectic structure of Al/Zn/MgZn ₂ ] in microscopic observation. Although the [Zn phase] may be contained in the hot-dip plated layer according to the present embodiment depending on the manufacturing conditions, the influence on the corrosion resistance resulting from the [Zn phase] was hardly seen. Therefore, even if the [Zn phase] is contained in the hot-dip plated layer, there is no problem in particular.

[MgZn ₂ phase]

[MgZn ₂ phase] is a phase that appears as an island phase as a clear boundary among the substrates of [a ternary eutectic structure of Al/Zn/MgZn ₂ ], and in fact, a small amount of Al may be dissolved therein. As far as the phase diagram is concerned, no other additive element is dissolved in this phase, or it is considered to be in a very small amount even if dissolved.

The MgZn ₂ phase forming [MgZn ₂ phase] and [the ternary eutectic structure of Al/Zn/MgZn ₂ ] can be clearly distinguished in microscopic observation. Although [MgZn ₂ phase] may not be contained in the hot-dip layer according to the present embodiment depending on the manufacturing conditions, it is contained in the hot-dip layer under most manufacturing conditions.

[Mg ₂ Si phase]

[Mg ₂ Si phase] is a phase seen as an island shape as a clear boundary in the solidified structure of the plating layer to which Si is added. As far as the phase diagram is concerned, Zn, Al, and other additive elements are not dissolved in [Mg ₂ Si phase] or are considered to be in very small amounts even if they are in solid solution. [Mg ₂ Si phase] can be clearly distinguished from other phases in the microscopic observation in the hot-dip plated layer.

The hot-dip plated layer of this embodiment is pulled up after a steel plate is immersed in a plating bath, and is formed by solidifying the molten metal adhering to the steel plate surface after that. At this time, at first, [Al phase] is formed, and thereafter, [a ternary eutectic structure of Al/Zn/MgZn ₂ ] is formed along with a decrease in the temperature of the molten metal.

Depending on the chemical composition of the hot-dip plated layer (that is, the chemical composition of the plating bath), [Mg ₂ Si phase], [ _{MgZn 2 phase} ] or [Zn phase] may be formed.

(1st area and 2nd area)

Next, the 1st area|region and the 2nd area|region of a hot-dip plated layer are demonstrated. A 1st area|region and a 2nd area|region exist in the hot-dip plated layer (the surface of a hot-dip plated layer) which concerns on this embodiment. As will be described later, the first region and the second region can be identified with the naked eye, under a magnifying glass, or under a microscope.

A 1st area|region may represent a linear part, a curved part, etc., and a 2nd area|region may represent a straight line part, a curved part, etc. When the first area represents a straight line portion, a curved portion, or the like, the first area may be arranged to have a predetermined shape, and the other areas may be referred to as a second area. In addition, when the second region represents a linear portion, a curved portion, or the like, the second region may be arranged to have a predetermined shape, and regions other than that may be referred to as a 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.

When the first region is arranged to have a predetermined shape, the first region may be formed to a size sufficient to discriminate the existence of the first region with the naked eye, under a magnifying glass, or under a microscope. The 2nd area|region in this case becomes an area|region which occupies parts other than the 1st area|region in a hot-dip plating layer (the surface of a hot-dip plating layer), and may occupy most of the hot-dip plating layer. Moreover, the 1st area|region may be arrange|positioned in the 2nd area|region. Specifically, the first region may be arranged so as to have a shape in which any 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 types thereof in the second region. . By adjusting the shape of the first region, any one of a straight line portion, a curved portion, a figure, a number, a symbol, a pattern, and a letter or a shape combining two or more of these is displayed on the surface of the hot-dip plated layer. This shape is an artificially formed shape and is not naturally formed.

On the other hand, when the second region is arranged to have a predetermined shape, the second region may be formed to a size sufficient to discriminate the existence of the second region with the naked eye, under a magnifying glass, or under a microscope. The 1st area|region in this case becomes a area|region which occupies parts other than a 2nd area|region in a hot-dip plated layer (the surface of a hot-dip plated layer), and may occupy most of the hot-dip plated layer. Moreover, the 2nd area|region may be arrange|positioned in the 1st area|region. Specifically, the second region may be arranged to have a shape in which any 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 types thereof in the first area. . By adjusting the shape of the second region, any one of a straight line portion, a curved portion, a figure, a number, a symbol, a pattern, and a letter or a shape combining two or more of these is displayed on the surface of the hot-dip plated layer. This shape is an artificially formed shape and is not naturally formed.

A 1st area|region and a 2nd area|region are not limited visually, You may distinguish under a magnifying glass or a microscope. Specifically, the shape, such as a straight line portion, constituted of the first region or the second region may be discernable in a field of view of 50 times or less. If the field of view is 50 times or less, a predetermined shape composed of the first region or the second region can be identified according to a difference in the surface state thereof.

The first region or the second region is preferably identifiable at 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 of the following (a) or (b).

(a) The first region is a region in which the average length of [Al phase] on the surface of the hot-dip plated layer is 200 µm or more, and in the second region, the average length of the [Al phase] on the surface of the hot-dip layer is 200 It is a region smaller than μm.

(b) the first region is a region in which the length Le in which [the ternary eutectic structure of Al/Zn/MgZn ₂ ] faces the steel plate at the boundary between the steel sheet and the hot-dip plated layer is greater than 0.3 with respect to the length L of the boundary, The second region is a region in which the length Le in 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 plated layer is 0.3 or less with respect to the length L of the boundary.

Hereinafter, the case of (a) and the case of (b) will be sequentially described.

(When the first area and the second area satisfy the above (a))

In the first region in the case of satisfying the above (a), metallic luster resulting from the Al phase having a long average length is observed. Therefore, compared to the second region, the gloss can be recognized as a linear shape. In one of the second regions, the metallic luster is recognized as a dot shape compared to the first region due to the Al phase having a short average length. For this reason, a 1st area|region and a 2nd area|region become distinguishable under the naked eye, a magnifying glass, or a microscope.

In the hot-dip plated layer, at least [Al phase] and [a ternary eutectic structure of Al/Zn/MgZn ₂ ] exist. The hot-dip plated layer has a form in which [Al phase] is included in the substrate of [a ternary eutectic structure of Al/Zn/MgZn ₂ ]. And [Al phase] is precipitated relatively early at the time of solidification of a hot-dip plated layer, and the form of [Al phase] at that time becomes a resinous phase.

When the above (a) is satisfied, the average length of the [Al phase] present in the first region is 200 µm or more.

When the average length of the [Al phase] is 200 µm or more, the relatively large resin crystal of the [Al phase] is exposed on the surface of the hot-dip plated layer, and the surrounding [Al/Zn/MgZn ₂ ternary eutectic structure], etc. In comparison, the metallic luster [Al phase] is long and irregularities are clear, so that it can be visually recognized in a linear shape as a whole.

On the other hand, the average length of the [Al phase] present in the second region is less than 200 µm. When the average length of [Al phase] is less than 200 µm, relatively small resin crystals of [Al phase] are exposed on the surface of the hot-dip plated layer, and the surrounding [Al/Zn/MgZn ₂ ternary eutectic structure], etc. In comparison, the metallic luster [Al phase] is short and irregularities become indistinct. The second region is preferably a region in which the average length of the [Al phase] is 180 µm or less, and more preferably a region in which the average length of the [Al phase] is less than 150 µm. The larger the difference between the average length of the [Al phase] in the first region and the average length of the [Al phase] in the second region, the easier it is to distinguish the first region and the second region, which is preferable. .

It is presumed that the first region is formed when the [Al phase] is generated with a relatively low number density and the [Al phase] itself is coarsened in the initial stage at the time of solidification of the hot-dip plated layer. In addition, it is estimated that the 2nd area|region is formed when [Al phase] is produced|generated with a comparatively high number density at the time of solidification of a hot-dip plated layer, and [Al phase] itself remains in a fine state without coarsening.

In order to control the size of the [Al phase], the cooling rate of the molten metal may be controlled at the time of solidification of the hot-dip plated layer. Specifically, when coarsening [Al phase], the cooling rate at the time of solidification is slowed, and when making [Al phase] fine, what is necessary is just to speed up the cooling rate at the time of solidification. When the steel sheet is immersed in the hot-dip plating bath and then pulled up, by partially increasing or slowing the cooling rate of the molten metal on the surface of the steel sheet, any one of a straight line portion, a curved portion, a figure, a number, a symbol, a shape, and a letter A shape or a shape obtained by combining two or more of these types can be intentionally or artificially expressed by a manufacturing method described later.

The average length of [Al phase] is measured by the following method. First, in each of a 1st area|region and a 2nd area|region among the surface of a hot-dipping layer, the area|region of 3 arbitrary fields is image|photographed with the reflection electron image of a scanning electron microscope. The size of each region is a rectangular region of 500 mu m x 360 mu m. In the photographed photograph, the Al phase of the resinous phase is confirmed. The dendritic Al phase has a shape having a main shaft and a secondary arm extending from the main shaft, as shown in FIG. 1 . With respect to the Al phase in the photograph, the length A in the longitudinal direction is measured. The length A of all Al phases is calculated|required in 3 views, and let the average value be the average length of the Al phase in a 1st area|region or a 2nd area|region. In addition, although the dendritic Al phase grows radially from the solidification nucleus in many cases, it is not limited to being arranged on the same plane, and when observed from the surface, only a part thereof, for example, only the tip of the secondary arm is observed, Alternatively, only the main shaft portion may be observed. Such an Al phase is excluded from the object of measurement. On the other hand, the object that can be observed so that the other phase is covered and not connected between the main shaft and the secondary arm.

(When the first region and the second region satisfy (b) above)

In the case of satisfying the above (b), the first region has a low metallic luster on its surface, and is a region in which white or gray is relatively exposed compared to the second region. One of the second regions is a region in which the metallic luster of the surface is relatively higher than that of the first region. For this reason, a 1st area|region and a 2nd area|region become distinguishable under the naked eye, a magnifying glass, or a microscope.

In the hot-dip plated layer, at least [Al phase] and [a ternary eutectic structure of Al/Zn/MgZn ₂ ] exist. The hot-dip plated layer has a form in which [Al phase] is included in the substrate of [a ternary eutectic structure of Al/Zn/MgZn ₂ ]. In addition, [Al phase] is precipitated relatively early at the time of solidification of a hot-dip plated layer, and the form of [Al phase] at that time becomes a resinous phase.

When the above (b) is satisfied, in the first region, [the ternary eutectic structure of Al/Zn/MgZn ₂ ] at the boundary between the steel sheet and the hot-dip plated layer has a length Le opposite to the steel sheet, with respect to the length L of the boundary A region greater than 0.3, preferably greater than 0.30. Accordingly, on the steel sheet side in the thickness direction of the hot-dip plated layer in the first region, [a ternary eutectic structure of Al/Zn/MgZn ₂ ] is relatively large, and [Al phase] and other phases or structures are relatively small. lose Thereby, on the surface side of the thickness direction of a hot-dip plated layer, the resinous [Al phase] comes to exist comparatively many. For this reason, it is estimated that the surface of the 1st area|region becomes comparatively large in surface roughness Ra, and the light which injects into the 1st area|region is diffusely reflected, and white or gray is revealed relatively compared with the 2nd area|region.

In the first region, at the boundary between the steel sheet and the hot-dip plated layer, the length Le in which [the ternary eutectic structure of Al/Zn/MgZn ₂ ] faces the steel sheet is preferably greater than 0.30 with respect to the boundary length L. That is, Le/L in the first region is preferably greater than 0.30.

On the other hand, in the second region, at the boundary between the steel sheet and the hot-dip plated layer, the length Le in which [the ternary eutectic structure of Al/Zn/MgZn ₂ ] faces the steel sheet is 0.3 or less with respect to the length L of the boundary, more preferably 0.30 or less. Accordingly, on the steel sheet side in the thickness direction of the hot-dip plated layer in the second region, [the ternary eutectic structure of Al/Zn/MgZn ₂ ] is relatively small, and the [Al phase] and other phases or structures are relatively large. lose Thereby, on the surface side of the thickness direction of a hot-dip plated layer, the resinous [Al phase] comes to exist comparatively little. For this reason, the surface of the 2nd area|region becomes comparatively small in surface roughness Ra, and it is estimated that the 2nd area|region exhibits metallic luster relatively compared with the 1st area|region.

In the second region, at the boundary between the steel sheet and the hot-dip plated layer, the length Le in which [the ternary eutectic structure of Al/Zn/MgZn ₂ ] faces the steel sheet is preferably 0.30 or less with respect to the boundary length L, more Preferably it is 0.15 or less area|region, More preferably, it is 0.1 or less area|region, Especially preferably, it is 0.10 or less. As the difference between Le/L in the first region and Le/L in the second region increases, the first region and the second region can be relatively easily distinguished, which is preferable.

The [Al phase] generated at the time of solidification of the hot-dip plated layer is usually precipitated in the entire thickness direction of the hot-dip plated layer. However, at the boundary between the steel sheet and the hot-dip plated layer, the [Al/Zn/MgZn ₂ ternary eutectic structure] intentionally or artificially controls the length Le opposing the steel sheet, so that the [Al phase] on the surface of the hot-dip plated layer is It is possible to control the abundance ratio. And since [Al phase] has a resin crystal form, when the abundance ratio of [Al phase] in the surface of the hot-dip plated layer increases, the surface roughness of the hot-dip layer becomes large, and on the other hand, in the surface of the hot-dip layer, When the abundance ratio of [Al phase] of [Al phase] becomes small, the surface roughness of a hot-dip plating layer becomes small. In this way, at the boundary between the steel sheet and the hot-dip plated layer, [the ternary eutectic structure of Al/Zn/MgZn ₂ ] controls the length Le opposing the steel sheet, thereby forming the first region and the second region on the surface of the hot-dip plated layer. can be formed

When an interfacial alloy layer containing Fe and Zn is formed at the boundary between the steel sheet and the hot-dip plated layer, the length Le at which [the ternary eutectic structure of Al/Zn/MgZn ₂ ] faces the steel sheet through the interfacial alloy layer What is necessary is just to make it into the said range. However, since the interfacial alloy layer is very thin compared to the thickness of the hot-dip plated layer, as described below, when measuring the length Le with a microscope, it depends on the magnification at the time of measurement, but the interfacial alloy layer cannot be confirmed. , the interface between the steel sheet and the hot-dip plated layer can be confirmed in some cases.

In this case, the first region is a region in which the length Le opposing the steel plate in [the ternary eutectic structure of Al/Zn/MgZn ₂ ] at the interface between the steel sheet and the hot-dip plated layer is greater than 0.3 with respect to the length L of the interface. do. In the second region, the length Le in 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 plated layer is 0.3 or less with respect to the length L of the interface.

At the boundary (interface) between the steel sheet and the hot-dip plated layer, the ratio of the length Le in which the [Al/Zn/MgZn ₂ ternary eutectic structure] faces the steel sheet to the length L of the boundary (interface) is determined by the following method can be measured with First, the cross section in the plate thickness direction of the Zn-Al-Mg-based hot-dip galvanized steel sheet is exposed. The cross section is set to 5 places each with respect to a 1st area|region and a 2nd area|region. Each section is photographed with a scanning electron microscope. In each cross section, a 150 µm-long region is arbitrarily selected among the boundaries (interfaces) between the steel sheet and the hot-dip plated layer. Let this length be the boundary length L (interface length L). Then, in the range of the selected boundary (interface) length, [the ternary eutectic structure of Al/Zn/MgZn ₂ ] was confirmed, and all [Al/Zn/MgZn ₂ The length Le of the sum of ternary process structure] is measured, and Le/L is calculated|required. Find Le/L in each of the five cross sections of the first region and the second region, and the average is [Al/ ternary eutectic structure of Zn/MgZn ₂ ] is the ratio of the length Le opposing the steel sheet.

The [Al phase] generated at the time of solidification of the hot-dip plated layer is usually precipitated in the entire thickness direction of the hot-dip plated layer. However, if a material that becomes solidification nuclei is placed on the surface of the steel sheet in advance, in the region where the solidification nuclei are arranged, when the molten metal adhering to the surface of the steel sheet solidifies, the solidification nuclei on the surface of the steel sheet are used as nuclei to form a large number of [Al phases]. ] is precipitated. The generated [Al phase] is segregated on the side relatively close to the steel sheet.

In addition, in the region where the solidification nuclei are arranged, the [Al phase] is generated at a relatively high density, so the [Al phase] itself does not coarsen and becomes a fine state. For this reason, in the region where the solidification nuclei are arranged, the [Al phase] does not grow to the surface side of the hot-dip plated layer, and a large amount of [Al phase] is precipitated near the boundary (interface) between the steel sheet and the hot-dip plated layer. As a result, in the [Al/Zn/MgZn ₂ ternary eutectic structure] in the region where the solidification nuclei are arranged, the amount of precipitation decreases, and [Al/Zn/MgZn ₂ 3 of 3 original eutectic structure], the ratio of the length Le opposing the steel sheet becomes small.

In the case of said (b), the area|region where solidification nuclei exist in the steel plate surface becomes a 2nd area|region of a hot-dip plated layer, and the area|region where solidification nuclei do not exist becomes a 1st area|region of a hot-dip plated layer. Further, since the second region is formed by the mechanism described above, solidification nuclei may exist at the boundary (interface) between the steel sheet and the hot-dip plated layer in the second region. More specifically, carbon (C), nickel (Ni), calcium (Ca), boron (B), phosphorus (P), titanium (Ti), Any one or two or more elements selected from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), zirconium (Zr), molybdenum (Mo), and tungsten (W), or among the elements described above A compound containing any 1 type or 2 or more types may exist.

In order to confirm the presence of the above-mentioned element or compound at the boundary (interface) between the steel sheet and the hot-dip plated layer, a glow discharge emission spectroscopy apparatus (GDS) is used to dig into the sample by sputtering while melting with the steel sheet in the second region. It can confirm by performing elemental analysis in the boundary of a plating layer.

As described above, before the steel sheet is immersed in the hot-dip plating bath, solidification nuclei are arranged on the surface of the steel sheet in a shape in which any one of a straight line portion, a curved portion, a figure, a number, a symbol, and a letter or a combination of two or more thereof Thereby, the 2nd area|region which has these shapes can be formed in a hot-dip plated layer.

In addition, before immersing the steel sheet in the hot-dip plating bath, on the surface of the steel sheet, the solidification nucleus By disposing , the first region having these shapes can be formed in the hot-dip plated layer.

Further, in the case of (b), the ratio of the X-ray diffraction intensity I(200) of the (200) plane of the Al phase to the X-ray diffraction intensity I(111) of the (111) plane on the surface of the hot-dip plated layer It is preferable that I(200)/I(111) is 0.8 or more, and 0.80 or more is more preferable. Regardless of the 1st area|region and 2nd area|region, ratio I(200)/I(111) may just be 0.8 or more, More preferably, 0.80 or more is good.

As the ratio I(200)/I(111) increases, among the [Al phases], the number of [Al phases] in which the (200) plane is parallel to the surface of the hot-dip plated layer increases, and the (111) plane becomes the surface of the hot-dip plated layer and [Al phase] becoming parallel decreases. Thereby, when seen from the surface of a hot-dip plated layer, there are many resin crystals seen in a cross shape, and a resin crystal seen in a hexagon shape decreases. In the process of solidification of the hot-dip plated layer from the molten state, when the resin crystal grows in a cross shape from the crystal nucleus when the [Al phase] precipitated as a primary crystal is viewed from the plating surface side, the angle between the branch and the branch is widened, and the plated surface It is easy to generate a flow path of the melt in a direction perpendicular to the , so that the [Al phase] on the plating surface is easily covered by the [Al/Zn/MgZn ₂ ternary eutectic structure] that finally solidifies. Thereby, when ratio I(200)/I(111) becomes high, the surface will appear metallic luster. Thereby, the whole external appearance of a hot-dip plated layer can be improved. Further, in the first region, a large amount of [Al/Zn/MgZn ₂ ternary eutectic structure] exists near the boundary (interface) in the plate thickness direction, and therefore a large amount of [Al phase] exists near the surface. There is this. On the other hand, the second region is the opposite. In a location where a large amount of [Al phase] is present on the surface, since the metallic luster is further emphasized for the above reason, the first region and the second region can be distinguished more clearly.

Ratio I(200)/I(111) in the surface of a hot-dip plating layer is controllable by adjusting the cooling rate after plating layer formation.

<Conversion treatment film layer and coating film layer>

The Zn-Al-Mg-based hot-dip plated steel sheet according to the present embodiment may have a chemical conversion coating layer or a coating layer on the surface of the hot-dip plated layer. Here, the kind of a chemical conversion treatment film layer or a coating film layer is not specifically limited, A well-known chemical conversion treatment film layer and a coating film layer can be used.

[Manufacturing method of Zn-Al-Mg-based hot-dip galvanized steel sheet]

Hereinafter, the manufacturing method of the Zn-Al-Mg type hot-dip plated steel sheet of this embodiment is demonstrated. In the following description, the case where the first region and the second region satisfy the above (a) or (b) will be sequentially described.

(Manufacturing method when the 1st area|region and the 2nd area|region satisfy|fill the said (a))

In the manufacturing method in the case where a 1st area|region and a 2nd area|region satisfy|fill the said (a), first, a hot-rolled steel sheet is manufactured, and hot-rolled sheet annealing is performed as needed. After pickling, cold rolling is performed and it is set as a cold rolled sheet. After degreasing and washing a cold-rolled sheet with water, annealing (cold-rolled sheet annealing) is carried out, the cold-rolled sheet after annealing is immersed in a hot-dip plating bath, and a hot-dip plating layer is formed. The hot-dip plating may be a continuous hot-dip plating method in which a steel sheet is continuously passed through a hot-dip plating bath, or a steel material obtained by processing the steel sheet into a predetermined shape or the steel sheet itself is immersed in a hot-dip plating bath and then pulled up.

It is preferable that a hot-dipping bath contains Al: 4 mass % or more and less than 25 mass %, Mg: 0 mass % or more and less than 10 mass %, and contains Zn and an impurity as balance. The hot-dip plating bath may contain Al: 4 to 22 mass% and Mg: 1 to 10 mass%, and the balance may contain Zn and impurities. Moreover, a hot-dip plating bath may contain Si:0.0001-2 mass %. In addition, the hot-dip plating bath is any one or two or more of Ni, Ti, Zr, Sr, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf. You may further contain 0.001-2 mass % in total. In addition, the average composition of the hot-dip plating layer of this embodiment is substantially the same as the composition of a hot-dip plating bath.

Although the temperature of a hot-dip plating bath changes with a composition, the range of 400-500 degreeC is preferable, for example. It is because a desired hot-dip plating layer can be formed as the temperature of a hot-dip plating bath is this range.

In addition, what is necessary is just to adjust the adhesion amount of a hot-dip plating layer by means, such as gas wiping, with respect to the steel plate pulled up from a hot-dip plating bath. It is preferable to adjust the adhesion amount of a hot-dip plated layer so that the total adhesion amount on both surfaces of a steel plate may become the range of 30-600 g/m<2>. When the adhesion amount is less than 30 g/m 2 , it is not preferable because the corrosion resistance of the hot-dip plated steel sheet is lowered. When the adhesion amount is more than 600 g/m 2 , drooping of the molten metal adhering to the steel sheet occurs and the surface of the hot-dip plated layer cannot be smoothed, so it is not preferable.

In order to form the first region and the second region satisfying the above (a), after adjusting the deposition amount of the hot-dip plated layer, while cooling the entire steel sheet, a non-oxidizing gas is locally applied to the molten metal by means of a gas nozzle. spray with As the non-oxidizing gas, a non-oxidizing gas such as nitrogen or argon may be used.

In order to make the first region into a predetermined shape, for the formation of the second region, the average cooling rate from the bath temperature to 345°C is cooled at 10°C/sec or more for substantially the entirety of the hot-dip plated layer. In addition, for the formation of the first region, the average cooling rate from the bath temperature to 345°C for a part of the hot-dip plated layer is cooled at a rate slower than that of the second region of less than 8°C/sec.

More preferably, for the formation of the second region, blow cooling or mist cooling is performed for almost the entirety of the hot-dip plated layer so that the average cooling rate from the bath temperature to 345°C is 15°C/sec or more, the first region is formed For this purpose, the average cooling rate from the bath temperature to 345°C is set to 5°C/sec or less by standing to cool (standing) without cooling a part of the hot-dip plated layer, or by spraying a relatively high-temperature non-oxidizing gas. The temperature of the non-oxidizing gas in this case may be, for example, in the range of 100 to 300°C. However, as long as the said average cooling rate can be satisfied, the temperature of a non-oxidizing gas does not need to be limited.

In addition, in order to make the second area|region into a predetermined|prescribed shape, for formation of the 1st area|region, the average cooling rate from a bath temperature to 345 degreeC is cooled at 8 degreeC/sec or less with respect to almost the whole hot-dip plated layer. In addition, for the formation of the second region, a portion of the hot-dip plated layer is cooled at an average cooling rate from the bath temperature to 345° C. at a rate of 10° C./sec or more, which is faster than that of the first region.

More preferably, for the formation of the first region, almost the entirety of the hot-dip plated layer is left to cool, and the average cooling rate from the bath temperature to 345° C. is 5° C./sec or less, while a part of the hot-dip plated layer is partially cooled for the formation of the second region. By injecting a relatively low-temperature non-oxidizing gas to the water, the average cooling rate from the bath temperature to 345°C is set to 15°C/sec or more. In order to reduce a cooling rate, you may perform cooling of a 1st area|region in 50-150 degreeC atmosphere. In addition, the temperature of the non-oxidizing gas at the time of cooling a 2nd area|region is good also as the range of 10-30 degreeC, for example, and good also as mist gas containing water droplets. However, as long as the said average cooling rate can be satisfied, it is not necessary to limit the atmospheric temperature at the time of cooling of a 1st area|region, and the temperature of a non-oxidizing gas.

(Manufacturing method when the 1st area|region and the 2nd area|region satisfy|fill (b) above)

In the manufacturing method in the case where the first region and the second region satisfy the above (b), solidification nuclei are arranged in a predetermined pattern on the steel sheet, then the steel sheet is immersed in a hot-dip plating bath, pulled up, and then cooled By solidifying the hot-dip plated layer, a Zn-Al-Mg-based hot-dip plated steel sheet is manufactured.

First, a hot-rolled steel sheet is manufactured, and hot-rolled sheet annealing is performed as needed. After pickling, cold rolling is performed and it is set as a cold rolled sheet. After the cold-rolled sheet is degreased and washed with water, it is annealed (cold-rolled sheet annealing), and the cold-rolled sheet after annealing is immersed in a hot-dip plating bath to form a hot-dip plated layer.

Here, during the period from cold rolling to immersion in the hot-dip plating bath, solidification nuclei are attached to the surface of the steel sheet, and any one or two or more of a straight line portion, a curved portion, a figure, a number, a symbol, and a letter. A pattern portion having a shape combining the The solidification nuclei may be attached at any stage between cold rolling and annealing of the cold-rolled sheet, between annealing of the cold-rolled sheet and immersion in a hot-dip bath, or immediately before the final annealing of the annealing of the cold-rolled sheet.

The component that forms solidification nuclei (hereinafter, sometimes referred to as 'solidification nucleation component') is not particularly limited as long as it is a component that forms solidification nuclei in the process of solidification of the plating layer. As the solidification nucleation component, for example, carbon (C), nickel (Ni), calcium (Ca), boron (B), phosphorus (P), titanium (Ti), manganese (Mn), iron (Fe), cobalt (Co), zirconium (Zr), molybdenum (Mo), any one or two or more of the elements selected from the group consisting of tungsten (W), or a compound containing any one or two or more of the above elements and the like. You may use the said component in combination of 1 or 2 or more. Examples of the method for attaching the solidification nuclei to the surface of the steel sheet include a method in which, in addition to the solidification nucleation component itself, a solidification nucleation component is contained in alloy foil, resin, surfactant, ink, oil, etc. to adhere to the surface of the steel sheet. These solidification nucleation components may be solid itself, and may be melt|dissolved or disperse|distributed in water or an organic solvent. Alternatively, the ink may be contained as a pigment or dye.

As a method for attaching the solidification nuclei to the surface of the steel sheet, for example, a method such as transferring, applying, or spraying a material containing a solidification nucleation component to the surface of the steel sheet can be exemplified. For example, a foil transfer method using hot stamping or cold stamping, etc., 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., Common printing methods can be used.

As an example of the transfer method using the alloy foil, there is a method in which an alloy foil containing a solidification nucleation component is adhered to the surface of a steel sheet, and a heated silicon roll is pressed against the alloy foil to transfer to the surface of the steel sheet.

As an example of a printing method using a plate, the rubber roll or rubber stamp is pressed against the surface of a steel plate while attaching an ink or surfactant containing a component that serves as a solidification nucleus to a rubber roll or rubber stamp having a printed pattern formed on its peripheral surface. Thus, a method of transferring ink or surfactant is exemplified. With this method, the solidification nucleation component can be efficiently adhered to the surface of the steel sheet with respect to the steel sheet that is continuously passed through.

The adhesion amount of coagulation nuclei is, for example, preferably in the range of 50 mg/m 2 or more and 5000 mg/m 2 or less. When the adhesion amount is less than 50 mg/m 2 , it is not preferable because there is a possibility that the first region is not formed to a degree that can be discerned with the naked eye, under a magnifying glass or under a microscope. On the other hand, since there exists a possibility that the adhesiveness of a hot-dip plated layer may fall when an adhesion amount is more than 5000 mg/m<2>, it is unpreferable.

Next, the steel sheet in which the pattern part which consists of solidification nuclei was formed is immersed in a hot-dip plating bath. The hot-dip plating may be a continuous hot-dip plating method in which a steel sheet is continuously passed through a hot-dip plating bath, or a steel material obtained by processing the steel sheet into a predetermined shape or the steel sheet itself is immersed in a hot-dip plating bath and then pulled up.

The composition of the hot-dip plating bath, the temperature of the hot-dip plating bath, the deposition amount of the hot-dip layer, and the control method of the deposition amount may be the same as the manufacturing method in the case where the first region and the second region satisfy the above (a).

In the manufacturing method in the case where the first region and the second region satisfy the above (b), it is necessary to adjust the temperature at the time of wiping as if in a molten state after adjusting the adhesion amount of the hot-dip plated layer. In addition, after the wiping pass, rapid cooling is required in order to generate many fine crystals of Al phase during plating. On the other hand, in order to adjust the direction of coagulation, the coagulation state must be maintained for a certain period of time. Therefore, within 1 second after passing the wiping, it is cooled to a temperature lower than the temperature at which solidification starts (liquidus temperature) and higher than the temperature at which plating is completely solidified (solidus temperature). In order to sufficiently precipitate fine crystals, it is preferable to cool the liquidus to a temperature 20° C. or more lower than the liquidus temperature within 1 second.

In addition, since it is also required that Al preferentially precipitate, it is more preferable to add to Al existing above the solidus line and stop the rapid cooling at a temperature higher than the temperature at which the MgZn _{2 phase is precipitated (referred to as the MgZn 2 phase} precipitation temperature line). . By cooling to a temperature of (MgZn ₂ phase precipitation temperature +5)°C or higher, only fine crystals of Al are produced, and the crystal orientation of Al is easily matched. After that, in order to grow crystals, it is cooled to 300°C or less by slow cooling at an average cooling rate of less than 10°C/sec.

When forming a chemical conversion treatment layer on the surface of a hot-dip plated layer after formation of a hot-dip plated layer, chemical conversion treatment is performed with respect to the hot-dip plated steel sheet after forming a hot-dip plated layer. The kind of chemical conversion treatment is not specifically limited, A well-known chemical conversion treatment can be used.

In addition, when forming a coating film layer on the surface of a hot-dip plated layer or the surface of a chemical conversion treatment layer, a coating process is performed with respect to the hot-dip plated steel sheet after forming a hot-dip plated layer or after forming a chemical conversion treatment layer. The kind of painting process is not specifically limited, Well-known painting process can be used.

As described above, in the Zn-Al-Mg-based hot-dip plated steel sheet of the present embodiment, the first region and the second region are included in the hot-dip plated layer, and the first region and the second region are the following (a) or (b) ), it is possible to identify the first region and the second region. Since the 1st area|region and the 2nd area|region are not formed by printing or painting, 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 plated layer. In addition, the 1st area|region and the 2nd area|region are not formed by grinding etc. the surface of a hot-dip plated layer. Therefore, the hot-dip plated steel sheet of the present embodiment is excellent in corrosion resistance.

Further, according to the present embodiment, it is possible to provide a Zn-Al-Mg-based hot-dip plated steel sheet having high durability in the first region or the second region formed into a predetermined shape and having suitable plating characteristics such as corrosion resistance. In particular, the first region or the second region can be intentionally or artificially shaped, and any one or two or more of these can be combined The first region or the second region may be arranged to form a single shape.

In addition, in the Zn-Al-Mg-based hot-dip plated steel sheet of this embodiment, various designs, trademarks, and other identification marks can be displayed on the surface of the hot-dip plated layer without printing or painting, so that the identification of the source of the steel sheet and Design, etc. can be improved. In addition, information necessary for process control, inventory control, etc. or arbitrary information requested by a consumer can also be provided to a Zn-Al-Mg type hot-dip plated steel sheet by the 1st area|region or 2nd area|region. Thereby, it can also contribute to the improvement of the productivity of a Zn-Al-Mg type hot-dip plated steel sheet.

Example

Next, an embodiment of the present invention will be described.

(Example 1)

After the steel sheet was degreased and washed with water, by performing reduction annealing, plating bath immersion, deposition amount control, and cooling, the No. Hot-dip plated steel sheets of 1-1 to 1-21 were prepared. After controlling the deposition amount, after the steel sheet was pulled up from the plating bath, the deposition amount was adjusted by gas wiping, and then, while the entire steel sheet was cooled, nitrogen gas was locally sprayed with a gas nozzle to the molten metal. Then, it cooled and completely solidified the molten metal. The injection range of nitrogen gas was controlled so that it might become a grid|lattice pattern with intervals of 50 mm. Table 1 shows the cooling conditions. The average cooling rates shown in Table 1 are all average cooling rates from the bath temperature to 345°C.

The lattice pattern was expressed in the second region under the cooling conditions A to C, and the lattice pattern was expressed in the first region under the cooling condition D. In addition, cooling conditions E and F were made into the pattern of a comparative example.

As for the cooling conditions A, 30 degreeC nitrogen gas was injected as a non-oxidizing gas, while cooling the whole steel plate in 120 degreeC atmosphere.

The cooling condition B sprayed 20 degreeC nitrogen gas as a non-oxidizing gas, standing to cool the whole steel plate.

The cooling condition C sprayed the nitrogen gas containing mist as a non-oxidizing gas, standing to cool the whole steel plate.

The cooling condition D sprayed 250 degreeC nitrogen gas as a non-oxidizing gas, cooling the whole steel plate with the nitrogen gas containing mist.

In addition, cooling condition E sprayed 30 degreeC nitrogen gas as a non-oxidizing gas, standing to cool the whole steel plate in 30 degreeC nitrogen gas. The cooling condition F allowed the whole steel plate to cool.

[Table 1]

[Table 2A]

[Table 2B]

Further, a Zn-Al-Mg-based hot-dip plated steel sheet was manufactured in the same manner as above. Thereafter, a grid pattern at intervals of 50 mm was printed on the surface of the hot-dip plated layer by an inkjet method. This result is No. 1-22 as shown in Tables 2A and 2B.

Further, a Zn-Al-Mg-based hot-dip plated steel sheet was manufactured in the same manner as above. Thereafter, the surface of the hot-dip plated layer was ground to form a grid pattern at intervals of 50 mm. This result is No. 1-23 as shown in Tables 2A and 2B.

About the obtained hot-dip plated steel sheet, the average length of the Al phase in a 1st area|region and a 2nd area|region was calculated|required. First, the boundary of a 1st area|region and a 2nd area|region was specified by visually observing the surface of a hot-dip plating layer. In an example in which it is difficult to determine the boundary, the nitrogen gas injection range is the first region or the second region.

The average length of [Al phase] was measured by the following method. First, in each of a 1st area|region and a 2nd area|region among the surface of a hot-dip plated layer, the area|region of 3 arbitrary fields was image|photographed with the reflection electron image of a scanning electron microscope. The size of each region was a rectangular region of 500 µm × 360 µm. In the photographed photograph, the dendritic [Al phase] was confirmed. The dendritic [Al phase] had a shape having a main shaft and a primary arm extending from the main shaft, as shown in FIG. 1 . With respect to the [Al phase] in the photograph, the length A in the longitudinal direction was measured. The length A of all the [Al phases] was calculated|required in 3 views, and the average value was made into the average length of the [Al phase] in a 1st area|region or a 2nd area|region. In addition, although the dendritic [Al phase] grows radially from the solidification nucleus in many cases, it is not limited to arranging in the same plane, and when observed from the surface, only a part of it, for example, a cancer tip, or , or only the main shaft part may be observed. Such [Al phase] was excluded from the measurement target. On the other hand, what could be observed so that the other phase was covered and not connected between the main shaft and the arm was set as the measurement object.

[identity]

Visual evaluation was performed on the basis of the following criteria for the test plates subjected to the grid pattern, those in an initial state immediately after production and those in an aging state exposed outdoors for 6 months. Both the initial state and the aging state made A to C a pass.

A: The grid pattern can be visually recognized even from 5m in front.

B: A grid pattern cannot be visually recognized from 5 m in front, but visibility from 3 m in front is high.

C: A grid pattern cannot be visually recognized from 3 m in front, but visibility from 1 m in front is high.

D: A grid pattern cannot be visually recognized from 1 m in front.

[Corrosion resistance]

The test plate was cut to 150 x 70 mm, and after 30 cycles of corrosion acceleration test CCT based on JASO-M609 was tested, the rust generation|occurrence|production situation was investigated, and it evaluated based on the following criterion. A to C were made pass.

A: There is no rust, and the lattice pattern and the other areas maintain a beautiful design appearance.

B: There is no rust generation, but a very slight change in the appearance of the design is seen in the grid pattern and other areas.

C: Although the appearance of the design is slightly damaged, the grid pattern and the area other than that are visually distinguishable.

D: The lattice pattern and the appearance quality of the regions other than that were remarkably deteriorated and could not be visually distinguished.

As shown in Table 2A and Table 2B, No. 1-1 to No. The Zn-Al-Mg-based hot-dip galvanized steel sheets of Examples 1-19 of the present invention were excellent in both identification and corrosion resistance. 2, No. The observation result by the scanning electron microscope of the 1st area|region of 1-4 is shown, and in FIG. 3, No. The observation result by the scanning electron microscope in the 2nd area|region of 1-4 is shown. In the [Al phase] in the first region shown in Fig. 2, the average length of the [Al phase] is larger than that of the [Al phase] in the second region shown in Fig. 3, and each has a different appearance. It can be seen that the first area and the second area are identifiable.

No. 1-20 and No. In 1-21, the lattice pattern was not confirmed because the cooling conditions were not appropriate.

In addition, No. 5, which printed a grid pattern by the inkjet method. In 1-22, the pattern became thin by the outdoor exposure for 6 months, and the discrimination property fell.

Moreover, No. which formed a grid|lattice pattern by grinding. In 1-23, the plating layer thickness of the ground location fell, and the corrosion resistance in the ground location fell.

Also, No. 1-1 to No. The plating layer of 1-23 contained [Al phase] and [a ternary eutectic structure of Al/Zn/MgZn ₂ ].

Fig. 4 shows the surface of the hot-dip plated steel sheet showing character strings (alphabet) by spraying nitrogen gas to the Zn-Al-Mg-based hot-dip plated layer.

According to the present invention, characters or marks can be intentionally expressed on the surface of the hot-dip galvanized steel sheet.

(Example 2)

The steel sheet after cold rolling was degreased and washed with water. Then, an ink containing a solidification nucleation component (fine particles of C or Ni) shown in Table 3 was adhered to a rubber plate having a shape on which a grid-like pattern at intervals of 50 mm was transferred. By pressing this rubber plate against the steel plate after washing with water, the ink was made to adhere to the surface of the steel plate. Then, cold-rolled sheet annealing was performed with respect to the steel sheet. The steel sheet after cold-rolled sheet annealing was immersed in a hot-dip plating bath, and then it was pulled up. Then, the adhesion amount was adjusted by gas wiping, and further cooling was performed. The cooling after adhesion amount control was cooled on the cooling conditions used as the temperature of the hot-dip plated layer 1 second after passing through gas wiping to the temperature shown in Table 4, and it stood to cool after that. In this way, the Nos. shown in Tables 5A and 5B. 2-1 to No. A Zn-Al-Mg-based hot-dip plated steel sheet of 2-20 was prepared. All of the steel sheet temperatures in Table 4 are below the temperature at which solidification starts (liquidus temperature), and above the temperature at which plating is completely solidified (solidus temperature), preferably (temperature at which MgZn ₂ precipitation starts +5) It was in the range of not less than °C and less than (liquidus temperature -20) °C.

A Zn-Al-Mg-based hot-dip galvanized steel sheet was manufactured in the same manner as above except that the steel sheet to which no solidification nuclei were attached was subjected to plating by a hot-dip plating bath. This is No. As 2-21, it is shown in Table 5A and Table 5B.

A Zn-Al-Mg-based hot-dip galvanized steel sheet was manufactured in the same manner as above except that the steel sheet to which no solidification nuclei were attached was subjected to plating by a hot-dip plating bath. A grid pattern at intervals of 50 mm was printed on the surface of the hot-dip plated layer of this steel sheet by an inkjet method. In this way, No. A Zn-Al-Mg-based hot-dip plated steel sheet of 2-22 was prepared.

A Zn-Al-Mg-based hot-dip galvanized steel sheet was manufactured in the same manner as above except that the steel sheet to which no solidification nuclei were attached was subjected to plating by a hot-dip plating bath. Thereafter, the surface of the hot-dip plated layer was ground to form a grid pattern at intervals of 50 mm. In this way, No. A Zn-Al-Mg-based hot-dip plated steel sheet of 2-23 was prepared.

With respect to the obtained hot-dip plated steel sheet, in the first region and in the second region, at the boundary between the steel sheet and the hot-dip plated layer, the ratio of the length Le at which the ternary eutectic structure faces the steel sheet to the length L of the boundary was determined. First, the boundary of a 1st area|region and a 2nd area|region was specified by visually observing the surface of a hot-dip plating layer. In an example in which it is difficult to discriminate the boundary, the adhesion range of the coagulation nucleus is assumed to be the second region.

The ratio of the length Le in which the ternary eutectic structure to the length L of the boundary faces the steel sheet at the boundary between the steel sheet and the hot-dip plated layer was measured by the following method. First, the cross section in the plate thickness direction of the Zn-Al-Mg-based hot-dip galvanized steel sheet was exposed. The cross section was made into 5 places each with respect to the 1st area|region and 2nd area|region. Each cross section was photographed with a scanning electron microscope. In each cross section, a 150-micrometer-long area|region was arbitrarily selected from the boundary of a steel plate and a hot-dip plated layer. This length was made into the boundary length L. Then, in the range of the selected boundary length, [ternary eutectic structure of Al/Zn/MgZn ₂ ] was confirmed, and all [ternary eutectic structure of Al/Zn/MgZn ₂ ] at the boundary between the steel sheet and the hot-dip plated layer was The length Le of the sum is measured, and Le/L is calculated|required. In each of the cross sections of the first region and the second region, Le/L is obtained, and the average is calculated as [Al/Zn/MgZn ₂ 3 of the boundary length L at the boundary between the steel sheet and the hot-dip plated layer. original process structure] was set as the ratio of the length Le opposing the steel plate.

In addition, in an arbitrary position on the surface of the hot-dip plated layer, the ratio I(200)/I of the X-ray diffraction intensity I(200) of the (200) plane of the Al phase and the X-ray diffraction intensity I(111) of the (111) plane (111) was found. The X-ray diffraction intensity I (200) of the (200) plane of the Al phase and the X-ray diffraction intensity I (111) of the (111) plane were measured by the X-ray diffraction method using CuKα1 ray on the surface of the hot-dip plated layer, , the ratio I(200)/I(111) was obtained. The peak intensity of the (200) plane of the Al phase was taken as the intensity of the (200) plane diffraction peak of Al indicated at 44.74° in the 2θ range. The peak intensity of the (111) plane of the Al phase was taken as the intensity of the (111) plane diffraction peak of Al, which appeared in the range of 38.47 in the 2θ range. For the X-ray diffraction measurement, an X-ray diffraction apparatus for micro-region measurement 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. X-rays emitted from the X-ray light source were condensed by a poly capillary tube. The irradiation range of the X-rays after condensing was made into a circle with a diameter of 1 mm.

[identity]

Visual evaluation was performed on the basis of the following criteria for the test plates subjected to the grid pattern, those in an initial state immediately after production and those in an aging state exposed outdoors for 6 months. Both the initial state and the aging state made A to C a pass.

A: The grid pattern can be visually recognized even from 8m in front.

B: A grid pattern cannot be visually recognized from 8 m in front, but visibility from 4 m in front is high.

C: A grid pattern cannot be visually recognized from 4 m in front, but visibility from 1 m in front is high.

D: A grid pattern cannot be visually recognized from 1 m in front.

[Corrosion resistance]

The test plate was cut to 150 x 70 mm, and after 30 cycles of corrosion acceleration test CCT based on JASO-M609 was tested, the rust generation|occurrence|production situation was investigated, and it evaluated based on the following criterion. A to C were made pass.

A: There is no rust, and the lattice pattern and the other areas maintain a beautiful design appearance.

B: There is no rust generation, but a very slight change in the appearance of the design is seen in the grid pattern and other areas.

C: Although the appearance of the design is slightly damaged, the grid pattern and the area other than that are visually distinguishable.

D: The appearance quality of the lattice pattern and the other regions is remarkably deteriorated and cannot be visually distinguished.

[Table 3]

[Table 4]

[Table 5A]

[Table 5B]

As shown in Table 5A and Table 5B, No. 2-1 to No. The Zn-Al-Mg-based hot-dip galvanized steel sheets of the Inventive Example No. 2-20 were excellent in both identification and corrosion resistance. 5, No. The cross-sectional observation result by the scanning electron microscope of the 1st area|region of 2-1 is shown, and in FIG. 6, No. The cross-sectional observation result by the scanning electron microscope of the 2nd area|region of 2-1 is shown. Since the first area and the second area have different appearances, it can be seen that they can be identified.

No. In 2-21, since no solidification nuclei were attached, the second region was not formed and a lattice-like pattern was not formed.

In addition, No. 5, which printed a grid pattern by the inkjet method. In 2-22, the pattern became thin by the outdoor exposure for 6 months, and designability fell. In addition, since no coagulation nuclei were attached, the second region was not formed.

Moreover, No. which formed a grid|lattice pattern by grinding. In 2-23, the plating layer thickness of the ground location fell, and the corrosion resistance in the ground location fell. In addition, since no coagulation nuclei were attached, the second region was not formed.

Also, No. 2-1 to No. The hot-dip plated layer of 2-23 contained [Al phase] and [a ternary eutectic structure of Al/Zn/MgZn ₂ ].

Fig. 7 shows the surface of the hot-dip plated steel sheet in which character strings (alphabetic characters) are represented by the second region in the Zn-Al-Mg-based hot-dip plated layer.

According to the present invention, characters or marks can be intentionally expressed on the surface of the hot-dip galvanized steel sheet.

According to the present invention, various designs, trademarks, and other identification marks can be displayed on the surface of the Zn-Al-Mg-based hot-dip plated layer without printing or painting, so that the identification or design of the source of the steel sheet can be improved. have. In addition, information necessary for process control, inventory control, etc. or arbitrary information requested by a consumer can also be provided to a Zn-Al-Mg type hot-dip plated steel sheet by the 1st area|region or 2nd area|region. Thereby, it can also contribute to the improvement of the productivity of a Zn-Al-Mg type hot-dip plated steel sheet. Therefore, it is fully equipped with industrial applicability.

Claims (8)

A steel plate and a hot-dip plated layer formed on the surface of the steel plate,
The hot-dip plated layer,
As an average composition, Al: 4 mass % or more and less than 25 mass %, Mg: 0 mass % or more and less than 10 mass % are contained, balance contains Zn and an impurity,
The metal structure includes [Al phase] and [a ternary eutectic structure of Al/Zn/MgZn ₂ ];
The hot-dip plated layer includes a first region and a second region,
The first region and the second region satisfy either of the following (a) or (b),
A Zn-Al-Mg-based hot-dip galvanized steel sheet, wherein the first region or the second region is arranged to have a predetermined shape.
(a) The first region is a region in which the average length of the [Al phase] on the surface of the hot-dip plated layer is 200 µm or more, and the second region is the [Al phase] on the surface of the hot-dip plated layer. ] is a region with an average length of less than 200 µm.
(b) in the first region, at the boundary between the steel sheet and the hot-dip plated layer, the length Le in which the [Al/Zn/MgZn ₂ ternary eutectic structure] faces the steel sheet is the length L of the boundary is a region greater than 0.3, and, in the second region, at the boundary between the steel sheet and the hot-dip plated layer, the length Le at which the [Al/Zn/MgZn ₂ ternary eutectic structure] faces the steel sheet is the length of the boundary It is an area|region which is 0.3 or less with respect to L. According to claim 1,
In the case where the first region and the second region are (b), the X-ray diffraction intensities I(200) and (111) of the (200) plane of the [Al phase] on the surface of the hot-dip plated layer ), the ratio I(200)/I(111) of the X-ray diffraction intensity I(111) of the plane is 0.8 or more, Zn-Al-Mg-based hot-dip galvanized steel sheet. 3. The method of claim 1 or 2,
Zn-Al-, wherein the first region or the second region is arranged to have a shape obtained by combining any one of a straight line portion, a curved portion, a figure, a number, a symbol, a pattern, or a letter, or a combination of two or more thereof. Mg-based hot-dip galvanized steel sheet. 4. The method according to any one of claims 1 to 3,
Wherein the first region or the second region is intentionally formed, a Zn-Al-Mg-based hot-dip galvanized steel sheet. 5. The method according to any one of claims 1 to 4,
The said hot-dip plated layer further contains Si:0.0001-2 mass % as an average composition, The Zn-Al-Mg type hot-dip plated steel sheet. 6. The method according to any one of claims 1 to 5,
A Zn-Al-Mg-based hot-dip plated steel sheet, wherein the hot-dip plated layer further contains, in an average composition, any one or two or more of Ni, Ti, Zr, and Sr in a total of 0.0001 to 2% by mass. 7. The method according to any one of claims 1 to 6,
The hot-dip plated layer further comprises, as an average composition, any one or two or more of Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, C, A Zn-Al-Mg-based hot-dip plated steel sheet containing 0.0001 to 2% by mass in total. 8. The method according to any one of claims 1 to 7,
A Zn-Al-Mg-based hot-dip plated steel sheet, wherein the amount of the hot-dip plated layer is 30 to 600 g/m 2 in total on both sides of the steel sheet.

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