Hot-dip galvanized steel

Abstract

In this hot-dip galvanized steel material, a plating layer has a chemical composition containing more than 10.0% but less than 45.0% Al, 4.0-15.0% Mg, 0.01-2.0% Si, and 0.03-1.50% Sr, with the remainder being Zn and impurities. The plating layer contains a Zn-Sr-based compound and a Zn-Sr-Si-based compound. In an element distribution profile when GDS analysis is performed from the surface of the plating layer toward a steel material, an expression (1) is satisfied where t is the thickness of the plating layer, Sr(surf) is the average value of qualitative analysis values of Sr from the surface of the plating layer to 0.05t, Sr(centre) is a qualitative analysis value in the range from 0.05t to 0.66t, and Sr(deep) is a qualitative analysis value in the range from 0.66t to t. (1): Sr(surf) < Sr(deep) < Sr(centre)

Description

[Technical Field]

[0001] The present invention relates to a hot-dip galvanized steel material. This application claims priority based on Japanese Patent Application No. 2023-067060, filed on April 17, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] When steel materials are used for a long period of time, it is preferable to apply some kind of rust prevention treatment to the steel material to make it resistant to corrosion. Hot-dip galvanizing is an inexpensive method of rust prevention for steel materials and is used in various fields where rust prevention of steel materials is required, such as civil engineering, construction, and automotive.

[0003] The corrosion protection measures by the plating layer are roughly determined by the inherent corrosion resistance of the plating layer and the thickness of the plating layer. For example, Patent Document 1 describes the production of plated steel sheets by a so-called continuous hot-dip plating method in which a steel sheet is continuously immersed in a hot-dip plating bath. The plated steel sheet is then processed into the shape of the part, thereby producing the part.

[0004] In recent years, various elements other than Al and Mg have been added to Zn alloy plating baths in order to impart properties other than corrosion resistance to the plating layer.

[0005] For example, Patent Documents 1 and 2 describe Zn-Al-Mg-based plating layers used as highly corrosion-resistant plating. These Zn-Al-Mg-based plating layers improve their design and corrosion resistance through structural control, and further disclose techniques for improving corrosion resistance by adding elements to the plating layer or actively forming corrosion products. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2018 / 139619 [Patent Document 2] International Publication No. 2019 / 230894 Summary of the Invention [Problem to be solved by the invention]

[0007] In the Zn-Al-Mg-based coating layer disclosed in Patent Document 1, elements such as Si and Sn added to the coating layer tend to bond with Mg, Al, or Zn in the Zn alloy to form intermetallic compounds with high melting points. Furthermore, Si, Sn, and the like also bond with steel components of the steel sheet passing through the coating bath to form intermetallic compounds with Fe and other elements, which then become fine particles (fine dross) that float and settle in the coating bath. These micro-sized intermetallic compounds adhere to the steel sheet during hot-dip coating, causing uncoated areas (areas where the coating layer is not formed on the steel sheet) and unevenness in the coating layer surface, resulting in poor appearance.

[0008] Furthermore, in the conventional Zn-Al-Mg-based plating layers described in Patent Documents 1 and 2, the method of adding elements to the final plating layer and the morphology of the intermetallic compounds in the plating layer have not been fully investigated, resulting in problems such as peeling of the plating layer (powdering phenomenon) caused by the intermetallic compounds and reduced workability.

[0009] An object of one embodiment of the present invention is to provide a hot-dip plated steel material that is capable of achieving both excellent workability and corrosion resistance. [Means for solving the problem]

[0010] In order to solve the above problems, each aspect of the present invention employs the following configuration. [1] A hot-dip galvanized steel material according to one aspect of the present invention is a hot-dip galvanized steel material having a steel material and a plating layer disposed on a surface of the steel material, The plating layer is composed of, in mass %, Al: over 10.0% and less than 45.0% Mg: 4.0% or more, 15.0% or less, Si: 0% or more, 2.0% or less, Sr: 0.03% or more, 1.50% or less and further comprising Sn: 0% or more, 0.7% or less, Bi: 0% or more, 0.3% or less, In: 0% or more, 0.3% or less, Ca: 0% or more, 0.6% or less, Y: 0% or more, 0.3% or less, La: 0% or more, 0.3% or less, Ce: 0% or more, 0.3% or less, Li: 0% or more, 0.3% or less, Ni: 0% or more, 1.0% or less, Cu: 0% or more, 1.0% or less, Ag: 0% or more, 0.25% or less, Sb: 0% or more, 0.25% or less, Pb: 0% or more, 0.25% or less, B: 0% or more, 0.5% or less, P: 0% or more, 0.5% or less, Ti: 0% or more, 0.25% or less, Co: 0% or more, 0.25% or less, V: 0% or more, 0.25% or less, Nb: 0% or more, 0.25% or less, Mn: 0% or more, 0.25% or less, Zr: 0% or more, 0.25% or less, W: 0% or more, 0.25% or less, Fe: 0% or more, 5.0% or less, It has a chemical composition containing the balance Zn and impurities, the plating layer contains a Zn—Sr-based compound and a Zn—Sr—Si-based compound, In an element distribution profile obtained by qualitatively analyzing the surface of the plating layer toward the steel material by glow discharge optical emission spectrometry, when the thickness of the plating layer is t, the average value of the qualitative analysis value of Sr from the surface of the plating layer to 0.05t is Sr(surf), the qualitative analysis value in the range from 0.05t to 0.66t starting from the surface of the plating layer is Sr(centre), and the qualitative analysis value in the range from 0.66t to t starting from the surface of the plating layer is Sr(deep), the following formula (1) is satisfied: Sr(surf) <Sr(deep)<Sr(centre) …(1) [2] The hot-dip coated steel material according to the above [1], wherein the chemical composition of the coating layer contains Sr: 0.10% or more and 1.50% or less, and in the X-ray diffraction pattern of the surface of the coating layer measured using Cu-Kα radiation under conditions of an X-ray output of 50 kV and 300 mA, the diffraction intensity of Zn-Sr compounds is I(SrZn 13 ), the following formula (2) may be satisfied. {I(14.48)+I(32.74°)} / 2×I(12.50°)}>2.0 …(2) In formula (2), I(n°) is the X-ray diffraction intensity at a diffraction angle of n°, and n is the diffraction angle (2θ) shown in formula (2). [3] In the hot-dip galvanized steel material described in [1] or [2] above, the chemical composition of the coating layer contains Si: 0.05% or more and 0.5% or less, and the coating layer may contain Zn-Sr-Si compounds and Zn-Al-Sr-Si compounds in an area ratio of 5% to 30% in a cross section along the thickness direction. [Effects of the Invention]

[0011] According to one embodiment of the present invention, it is possible to provide a hot-dip plated steel material that is capable of achieving both excellent workability and corrosion resistance. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 is a graph showing an example of an element distribution profile, showing the results of a GDS analysis performed on a coating layer of a hot-dip coated steel material according to an embodiment of the present invention. [Figure 2] 2 shows an example of an X-ray diffraction pattern of a plating layer according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a hot-dip plated steel material according to one embodiment of the present invention will be described. In this specification, the "%" designation for the content of each element in the chemical composition of the plating layer means "mass %" unless otherwise specified. Furthermore, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. When the numerical values ​​before and after "to" are followed by "greater than" or "less than," the numerical range does not include these numerical values ​​as the lower or upper limit.

[0014] In this specification, "corrosion resistance" refers to the corrosion resistance of the plating layer itself. Zn-based plating layers have a sacrificial corrosion protection effect on steel materials. Therefore, in the corrosion process of plated steel sheets, the plating layer corrodes and turns into white rust before the steel material corrodes, and the white-rusted plating layer disappears, after which the steel material corrodes and red rust appears. Furthermore, the term "sacrificial corrosion protection" as used herein refers to the property of inhibiting corrosion of steel at exposed portions of the steel (for example, the cut end surface of a plated steel or a portion where the steel is exposed due to cracking of the hot-dip plating layer during processing).

[0015] First, we investigated the relationship between the intermetallic compounds formed in the Zn-Al-Mg-based coating layer and the workability of the coated steel material. The results of this investigation are explained below.

[0016] Generally, when a plating layer contains intermetallic compounds with covalent bonds, they become hard particles, increasing the hardness of the entire plating layer. In addition, since intermetallic compounds also have excellent insulating properties, their inclusion in the plating layer leads to high corrosion resistance.

[0017] On the other hand, if the plating layer contains an excessive amount of intermetallic compounds, the entire plating layer becomes hard, which makes the plating layer more susceptible to damage when the plated steel material is subjected to forming processing, and may result in peeling of the plating layer, such as powdering. Therefore, it is not practically preferable to include a large amount of intermetallic compounds in the plating layer. Therefore, there has been a demand for a plating layer that has a desired level of hardness and high corrosion resistance, and also has good workability and does not peel off.

[0018] One technique for improving the hardness and corrosion resistance of a coating layer is to incorporate calcium into the coating. When a large amount of calcium is incorporated into the coating layer, it forms intermetallic compounds with Zn, Al, and other elements in the coating layer. The melting point of this calcium-containing intermetallic compound is very high during the solidification process of Zn-Al-Mg hot-dip coating. Therefore, calcium in the coating layer becomes large calcium-containing intermetallic compounds in the early stages after the steel is removed from the coating bath, and these compounds grow within the coating layer.

[0019] In a typical hot-dip plating process, the surface of the coating layer is significantly cooled by the outside air, so solidification of the coating layer begins from the surface. In a Ca-containing bath, a similar mechanism occurs, where precipitation of Ca-containing intermetallic compounds begins in areas with low free energy, such as the surface or interface of the coating layer. As a result, Ca-containing intermetallic compounds tend to accumulate, particularly on the surface of the coating layer, and can grow coarsely, forming a series of layers of Ca-containing intermetallic compounds.

[0020] In the case of a plating layer in which Ca-containing intermetallic compounds are connected in layers, the Ca-containing intermetallic compounds may undergo brittle fracture during forming, causing the plating layer to peel off from the surface, a phenomenon known as "powdering." Therefore, it has been difficult to improve the hardness, workability, and corrosion resistance of a plating layer containing a high concentration of Ca.

[0021] Therefore, the inventors investigated elements that produce the same effect as Ca and found that Sr is effective. Specifically, it was found that Sr forms covalent bonds with Zn, Al, Si, etc. to form Sr-based intermetallic compounds that have excellent corrosion resistance and hardness.

[0022] [Hot-dip galvanized steel] The hot-dip plated steel material according to this embodiment will be described in detail below. The hot-dip plated steel material of this embodiment has a steel material and a plating layer disposed on the surface of the steel material. The average chemical composition of the plating layer is, in mass%, Al: over 10.0% and less than 45.0% Mg: 4.0% or more, 15.0% or less, Si: 0% or more, 2.0% or less, Sr: 0.03% or more, 1.50% or less and further comprising Sn: 0% or more, 0.7% or less, Bi: 0% or more, 0.3% or less, In: 0% or more, 0.3% or less, Ca: 0% or more, 0.6% or less, Y: 0% or more, 0.3% or less, La: 0% or more, 0.3% or less, Ce: 0% or more, 0.3% or less, Li: 0% or more, 0.3% or less, Ni: 0% or more, 1.0% or less, Cu: 0% or more, 1.0% or less, Ag: 0% or more, 0.25% or less, Sb: 0% or more, 0.25% or less, Pb: 0% or more, 0.25% or less, B: 0% or more, 0.5% or less, P: 0% or more, 0.5% or less, Ti: 0% or more, 0.25% or less, Co: 0% or more, 0.25% or less, V: 0% or more, 0.25% or less, Nb: 0% or more, 0.25% or less, Mn: 0% or more, 0.25% or less, Zr: 0% or more, 0.25% or less, W: 0% or more, 0.25% or less, Fe: 0% or more, 5.0% or less, The balance includes Zn and impurities.

[0023] The coating layer of the hot-dip coated steel material of this embodiment contains Zn-Sr compounds and Zn-Sr-Si compounds. Furthermore, in an element distribution profile obtained by qualitatively analyzing the coating layer from its surface toward the steel material by glow discharge optical emission spectrometry, when the thickness of the coating layer is t, the average value of the qualitative analysis values ​​of Sr from the surface to 0.05t is Sr(surf), the qualitative analysis value from 0.05t to 0.66t starting from the surface of the coating layer is Sr(centre), and the qualitative analysis value from 0.66t to t starting from the surface of the coating layer is Sr(deep), the following formula (1) is satisfied:

[0024] Sr(surf) <Sr(deep)<Sr(centre) …(1)

[0025] (Steel) First, the steel material (original sheet) to be plated will be described. The steel material is, for example, mainly a steel plate, but its size is not particularly limited. The steel plate may be any steel plate that can be used in a normal hot-dip galvanizing process. Specifically, this applies to steel plates that can be used in processes such as continuous hot-dip galvanizing lines (CGLs) where the steel plate is immersed in molten metal and solidified. The size of the steel plate may be, for example, 10 mm or less in thickness and 2000 mm or less in width, but the size of the steel plate is not limited to these.

[0026] The quality of the steel material is not particularly limited, and examples of applicable steel materials include general steel, pre-plated steel thinly plated with various metals, Al-killed steel, ultra-low carbon steel, high carbon steel, various high-tensile steels, some high alloy steels (steels containing elements that strengthen corrosion resistance such as Ni and Cr), steel for bolts, and steel wire rods for bridge cables. More specifically, the steel material includes, for example, hot-rolled steel sheets as defined in JIS G 3131 (2018), cold-rolled steel sheets as defined in JIS G 3141 (2017), general structural rolled steel materials corresponding to so-called SS materials, so-called general steels as defined in hot-rolled steel sheets as defined in JIS G 3193 (2019), pre-plated steels thinly plated with various metals as defined in JIS H 8641 (2021), JIS G 3302 (2019), 3303 (2017), 3313 (2017), 3314 (2019), 3315 (2017), 3317 (2019), and 3321 (2019), rolled steel materials for building structures as defined in JIS G 3136 (2012), and JIS G Applicable steels include Al-killed steels, ultra-low carbon steels, and high carbon steels described in JIS G 3126 (2015), as well as various high-tensile steels and some high alloy steels (steels containing elements that strengthen corrosion resistance, such as Ni and Cr) described in JIS G 3113 (2018), 3134 (2018), and 3135 (2018).

[0027] In addition, the manufacturing process of steel materials includes general processes such as iron and steel making processes using blast furnaces or electric furnaces, hot rolling processes, pickling processes, cold rolling processes, and heat treatment processes.

[0028] (plating layer) Next, the plating layer provided on the steel material will be described. The plating layer according to this embodiment includes a Zn-Al-Mg alloy layer. The inclusion of alloying elements such as Al and Mg in the Zn phase improves corrosion resistance. Therefore, in the case of a plating layer containing such a Zn phase, even a thin film (e.g., about half the thickness of a normal Zn plating layer) can exhibit corrosion resistance equivalent to that of a normal Zn plating layer. Similarly, even when the plating layer according to this embodiment is thin, it can maintain corrosion resistance equivalent to or greater than that of a conventional Zn plating layer.

[0029] The Zn-Al-Mg alloy layer is made of a Zn-Al-Mg alloy, which means a ternary alloy containing Zn, Al, and Mg.

[0030] The plating layer may also include an Al-Fe-based interfacial alloy layer (however, the thickness is less than 5 μm). The Al-Fe-based interfacial alloy layer is an interfacial alloy layer between the steel material and the Zn-Al-Mg-based alloy layer and is in contact with the surface of the steel material. That is, the plating layer of this embodiment may have a single-layer structure composed of a Zn-Al-Mg-based alloy layer, or a laminated structure composed of a Zn-Al-Mg-based alloy layer and an Al-Fe-based interfacial alloy layer disposed between the Zn-Al-Mg-based alloy layer and the steel material. In the case of a single-layer structure, the plating layer on the steel material is composed of a single layer composed of a Zn-Al-Mg-based alloy. That is, the plating layer of this embodiment does not include a multi-layer structure, such as a laminated structure of an Al plating layer and a Zn plating layer. Furthermore, when the plating layer of this embodiment has a laminated structure, the Zn-Al-Mg-based alloy layer may be a layer that constitutes the surface of the plating layer.

[0031] Although the Al-Fe-based interfacial alloy layer does not significantly affect corrosion resistance, it does affect the adhesion of the coating layer and workability (presence or absence of cracks) during processing of hot-dip galvanized steel. In particular, the Al-Fe-based interfacial alloy layer may affect powdering resistance, which indicates the degree of peeling of the coating layer during processing. Generally, a thinner Al-Fe-based interfacial alloy layer reduces the number of crack initiation points in the coating layer during processing, thereby improving powdering resistance. Therefore, for hot-dip galvanized steel that may be subjected to high processing when used as a component, it is preferable that the thickness of the Al-Fe-based interfacial alloy layer be as thin as possible. Specifically, the thickness of the intermetallic compound constituting the Al-Fe-based interfacial alloy layer is less than 5 μm. This thickness is preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less. It may even be 0.3 μm or less. This suppresses cracking during processing and further improves powdering resistance. Furthermore, the ratio of the thickness of the Al-Fe interfacial alloy layer to the thickness of the plating layer is less than 10% on average, and more preferably less than 5%.

[0032] An Al-Fe-based interfacial alloy layer is formed on the surface of a steel material, specifically, between the steel material and a Zn-Al-Mg-based alloy layer. The Al-Fe-based interfacial alloy layer is a layer whose structure is dominated by the Al5Fe2 phase. The Al-Fe-based interfacial alloy layer is formed by atomic diffusion between the base steel (steel sheet) and the coating bath. When a continuous hot-dip coating method is used as a manufacturing method, an Al-Fe-based interfacial alloy layer is likely to be formed in a coating layer containing Al. In this embodiment, since the coating bath contains a certain concentration of Al or more, the Al5Fe2 phase is formed in the Al-Fe-based interfacial alloy layer in large amounts. However, because atomic diffusion takes time, the Fe concentration in the Al-Fe-based interfacial alloy layer is not uniform, and the Fe concentration may be higher in the portion closer to the base steel. Therefore, the Al-Fe-based interfacial alloy layer may partially contain small amounts of AlFe phase, Al3Fe phase, Al5Fe2 phase, etc. Furthermore, since the coating bath also contains a certain concentration of Zn, the Al-Fe-based interfacial alloy layer may also contain a small amount of Zn. Furthermore, the Al-Fe-based interface alloy layer may contain a small amount of Si, which tends to accumulate at the interface.

[0033] In this embodiment, Si is contained in the plating layer. A portion of the Si is incorporated into the Al-Fe-based interfacial alloy layer to form an Al-Fe-Si intermetallic compound phase. The identified intermetallic compound phase is the AlFeSi phase. Isomers of the AlFeSi phase include the α phase, β phase, q1 phase, and q2 phase. Therefore, these AlFeSi phases may be detected in the Al-Fe-based interfacial alloy layer. An Al-Fe-based interfacial alloy layer containing these AlFeSi phases is also referred to as an Al-Fe-Si alloy layer.

[0034] Next, the average chemical composition of the plating layer will be described. When the plating layer has a single-layer structure of a Zn-Al-Mg alloy layer, the average chemical composition of the entire plating layer is the average chemical composition of the Zn-Al-Mg alloy layer. When the plating layer has a multilayer structure consisting of an Al-Fe interfacial alloy layer and a Zn-Al-Mg alloy layer, the average chemical composition is the combined average chemical composition of the Al-Fe interfacial alloy layer and the Zn-Al-Mg alloy layer.

[0035] In the plating layer of this embodiment, the thickness of the Al-Fe-based interfacial alloy layer is preferably 10% or less of the total thickness of the plating layer. When the thickness of the Al-Fe-based interfacial alloy layer is sufficiently small relative to the total thickness of the plating layer, the Fe concentration of the plating layer is often within 5%. Therefore, the average chemical composition of the plating layer is generally similar to the components of the Zn-Al-Mg-based alloy layer. Furthermore, traces of the original plating material are unlikely to remain as chemical components of the plating layer. Therefore, the average chemical composition of the plating layer is nearly identical to the components of the plating bath used in its production.

[0036] Al: Over 10.0% and less than 45.0% Al is an element that mainly constitutes the coating layer. If the Al content is 10.0% or less, a sufficient amount of Zn-Al phase may not be secured. Therefore, the Al content is more than 10.0%. On the other hand, if the Al content is 45.0% or more, the Al-Zn (α) phase becomes the main component in the coating layer, and the Al-Zn (β) phase does not form. Therefore, the upper limit of the Al content is less than 45.0%. The lower limit of the Al content is preferably 15.0% or more. Furthermore, the upper limit of the Al content is preferably 30.0% or less, more preferably 25.0% or less.

[0037] Mg: 4.0% or more, 15.0% or less Like Zn, Mg is an element that mainly constitutes the coating layer. In the coated steel sheet according to this embodiment, Mg is an important element for improving sacrificial corrosion protection. If the Mg content in the coating layer is less than 4.0%, the effect of improving sacrificial corrosion protection is not as clear as when no Mg is contained. Therefore, the Mg content is set to 4.0% or more. On the other hand, if excessive Mg is added to a Zn-Al-Mg-based coating bath, a rapid oxidation reaction occurs at the surface of the coating bath, making stable coating impossible. Therefore, to ensure stable coating and good manufacturability, the Mg content in the coating layer is set to 15% or less.

[0038] Si: 0% or more, 2.0% or less Si suppresses the Al-Fe reaction, thereby suppressing the formation of an Al-Fe-based interfacial alloy layer. Furthermore, Si is incorporated into a portion of the Al-Fe-based interfacial alloy layer to form an Al-Fe-Si compound. Note that Si may not be included in this embodiment. However, if Si is not included, the Al-Fe reaction becomes active, the thickness of the Al-Fe alloy layer increases, and powdering may occur during processing, potentially impairing corrosion resistance. On the other hand, if the Si content is 0.01% or more, the growth rate of the interfacial alloy layer decreases. However, if the Si content exceeds 2.0%, Si bonds with Mg to form a large amount of an intermetallic compound having the composition MgSi, which significantly increases the viscosity of the coating bath, reducing the amount of molten metal adhering to the steel material when it is removed from the coating bath and resulting in an extremely thin coating layer. Furthermore, the coating appearance is significantly impaired. For these reasons, the upper limit of the Si content is set to 2.0%. The preferred range is 0.05 to 0.50%, more preferably 0.10 to 0.40%, and even more preferably 0.20 to 0.30%. If the Si content is 1.50% or less, almost no Mg2Si is formed.

[0039] Sr: 0.03% or more, 1.50% Sr is an element that produces the same effects as Ca. Sr forms covalent bonds with Zn, Al, Si, etc. to form intermetallic compounds that have excellent corrosion resistance and hardness. If the Sr content is less than 0.03%, the amount of intermetallic compounds formed is insufficient, and the effects of improving corrosion resistance and hardness are not fully achieved. On the other hand, if the Sr content exceeds 1.50%, excessive Sr-based intermetallic compounds are formed in the coating layer, making the entire coating layer hard. As a result, when the coated steel is used as a material for forming, the coating layer is easily damaged, and peeling of the coating layer, such as powdering, may occur. Therefore, the Sr content is set to 0.03% or more and 1.50% or less.

[0040] Sn: 0% or more, 0.7% or less Bi: 0% or more, 0.3% or less In: 0% or more, 0.3% or less Total amount of Sn, Bi and InΣX: 0% or more, 0.7% or less The elements Sn, Bi, and In are elements that promote softening of the plating layer when contained in the plating layer. Sn, Bi, and In are optional elements, so their respective contents are set to 0% or more. The inclusion of Sn tends to form Mg9Sn5 in the plating layer. Bi also forms Mg3Bi2, and In also forms Mg3In. These elements are softer than the MgZn2 phase and have good workability, and their inclusion in the plating layer clearly improves workability. Furthermore, these elements exhibit very base electrochemical properties, providing a high level of sacrificial corrosion protection. By incorporating at least one of Sn, Bi, and In within the above ranges, improved corrosion resistance in the processed area can be achieved.

[0041] Ca: 0% or more, 0.6% or less Y: 0% or more, 0.3% or less La: 0% or more, 0.3% or less Ce: 0% or more, 0.3% or less Li: 0% or more, 0.3% or less Ni: 0% or more, 1.0% or less Cu: 0% or more, 1.0% or less Ag: 0% or more, 0.25% or less Sb: 0% or more, 0.25% or less Pb: 0% or more, 0.25% or less B: 0% or more, 0.5% or less P: 0% or more, 0.5% or less Ti: 0% or more, 0.25% or less Co: 0% or more, 0.25% or less V: 0% or more, 0.25% or less Nb: 0% or more, 0.25% or less Mn: 0% or more, 0.25% or less Zr: 0% or more, 0.25% or less W: 0% or more, 0.25% or less Ca, Y, La, Ce, Sr, Li, Ni, Cr, Mo, Sb, Pb, B, P, Ti, Co, V, Nb, Mn, Zr, and W all form intermetallic compounds with Si, Zn, Al, etc. However, if the content of these elements is within the above range, they will not affect the initial corrosion of the plating layer. On the other hand, if these elements are contained in excess, a potential difference will occur in the plating layer, which may result in the occurrence of a lot of initial white rust. Therefore, if these elements are contained, it is best to keep them within the above range.

[0042] Fe: 0% or more, 5.0% or less The hot-dip plated steel material of this embodiment is produced by a continuous hot-dip plating method, and therefore, Fe may diffuse from the base material to be plated into the plated layer during production. As described above, in this embodiment, the Al concentration of the plated layer is high, and an Al-Fe-based interfacial alloy layer may be formed, but its thickness is thin. As a result, the plated layer may contain up to 5.0% Fe, but as long as the Fe concentration is limited to 5.0% or less, there is no effect on the frequency of cracks in the plated layer, etc. Therefore, the Fe content is set to 0 to 5.0%. The Fe content may be greater than 0%.

[0043] Remainder: Zn and impurities The balance preferably contains Zn. Since the hot-dip plated steel material of this embodiment is a highly versatile Zn-based plated steel material, the element that constitutes the main phase of the plated layer is Zn.

[0044] Impurities are components contained in raw materials or components mixed in during the manufacturing process, but not intentionally added. For example, trace amounts of components other than Fe may be mixed into the plating layer as impurities due to atomic diffusion between the steel (base steel) and the plating bath. Furthermore, since metals with 3N purity are typically used to manufacture plating alloys, the total impurity concentration may be approximately 0.03% or less.

[0045] To identify the average chemical composition of the plating layer, the plating layer is stripped and dissolved using an acid containing an inhibitor that suppresses corrosion of the base steel (steel material) to obtain an acid solution. The resulting acid solution is then measured using ICP atomic emission spectroscopy or ICP-MS to obtain the chemical composition. There are no particular restrictions on the type of acid, as long as it can dissolve the plating layer. By measuring the area and weight before and after stripping, the plating adhesion amount (g / m 2 ) can also be obtained at the same time.

[0046] Next, the intermetallic compounds contained in the plating layer will be described. The plating layer according to this embodiment is a Zn-Al-Mg alloy plating, and therefore contains a Zn phase, an Al phase, and an MgZn2 phase. The plating layer according to this embodiment also contains an Sr-containing intermetallic compound. Furthermore, the plating layer according to this embodiment may contain other intermetallic compounds.

[0047] MgZn2 phase The MgZn2 phase is intentionally included in the plating layer to improve its corrosion resistance. By including a certain amount of the MgZn2 phase in the plating layer, corrosion resistance in a water-soaked environment can be further improved.

[0048] Zn phase (Al-Zn phase, Zn-Al phase) The Zn phase exists primarily as a ternary eutectic structure (Zn / Al / MgZn2 ternary eutectic structure). Furthermore, when the coating layer contains a large amount of Al, the Zn phase may dissolve within the Al phase, as Al and Zn mix together in the solid state to form an Al-Zn phase. Alternatively, Al may dissolve within the Zn phase to form a Zn-Al phase (with an Al concentration of up to about 20%). A phase composed of Zn and Al is highly workable.

[0049] Al phase The Al phase exists in the coating layer in the form of clumps of primary Al crystals. The Al phase dissolves various elements, particularly Zn, within the phase during the solidification process of the coating layer. Because the coating layer of this embodiment has a high Al content, the Al phase becomes supersaturated with elements such as Zn during the solidification process. During the solidification process, the Al phase forms a dendrite structure that spreads in a tree-like manner within the coating layer, forming the skeleton of the coating layer. Because the Al phase is soft and highly workable, it hinders the growth of cracks that occur and plays a role in reducing fatal defects in the coating layer.

[0050] Sr-containing intermetallic compounds The plating layer according to this embodiment contains Sr-containing intermetallic compounds, such as Zn-Sr compounds, Zn-Sr-Si compounds, and Zn-Al-Sr-Si compounds, which are formed in the plating layer due to the inclusion of Sr in the plating layer.

[0051] Intermetallic compounds formed in plating layers generally have the effect of increasing corrosion resistance and hardness due to the complex bonding of individual atoms. However, excessive content can lead to a loss of plastic deformability. In particular, when metal compounds are formed in continuous layers on the plating surface and interface, they can aggregate and peel during bending, and during corrosion, differences in corrosion rate can cause surface and / or interfacial peeling. Therefore, it is necessary to reduce the accumulation of intermetallic compounds near the surface and interface.

[0052] Here, Ca is known as an element effective in improving the corrosion resistance and hardness of the coating layer, but as mentioned above, Ca-containing intermetallic compounds are compounds that tend to form layers, and are particularly prone to accumulating at interfaces. This is because when an excessive amount of Ca is contained in a Zn-Al-Mg coating layer, an intermetallic compound based on CaZn4 is easily formed. In contrast, Sr has almost the same effect as Ca, but in Zn-Sr compounds, SrZn 13 It is an intermetallic compound based on Ca, and tends to accumulate less at interfaces compared to Ca-containing intermetallic compounds. Furthermore, the more the intermetallic compounds are concentrated in the center of the coating layer, the better the workability becomes, so that powdering does not occur even under severe processing conditions. In particular, by adding an Sr-containing intermetallic compound so as to satisfy the following formulas, the hardness of the coating layer is further increased, improving scratch resistance and improving corrosion resistance on flat surfaces, ensuring a hard coated steel material with good workability and corrosion resistance.

[0053] In this way, by including an Sr-containing intermetallic compound in the center of the plating layer, the powdering phenomenon can be more efficiently avoided, and both workability and corrosion resistance can be improved.

[0054] In order to further enjoy the above-mentioned effects, it is preferable that the Zn-Sr-Si compound and the Zn-Al-Sr-Si compound are contained in an area ratio of 5 to 30%. Excessive Si in the coating layer forms Mg2Si. However, Mg2Si has strong sacrificial protection properties, making it undesirable for improving corrosion resistance on flat surfaces. On the other hand, Zn-Sr-Si and Zn-Al-Sr-Si compounds exhibit a slightly less noble potential than Zn, do not exhibit excessive sacrificial protection, and corrode slowly relative to Zn. In other words, Zn-Sr-Si and Zn-Al-Sr-Si compounds, which have complex metal element bonds, exhibit a low corrosion rate while exhibiting an appropriate potential. The inclusion of Si in solid solution further strengthens the bond, significantly improving corrosion resistance. Specifically, appropriately controlling the area fraction of Zn-Sr-Si and Zn-Al-Sr-Si compounds significantly improves corrosion resistance. The higher the area fraction of Zn-Sr-Si and Zn-Al-Sr-Si compounds, the better. However, because of the upper limit of the amount of Sr that can be contained in the plating layer, the total area fraction of Zn-Sr-Si compounds and Zn-Al-Sr-Si compounds is substantially 30% or less.

[0055] These intermetallic compounds can be measured using an electron probe microanalyzer (EPMA). Specifically, first, an EPMA analysis is performed on a cross section of the plating layer along the thickness direction at a magnification of 1000x, and all structures in which Zn, Sr, and Si are detected in the same location are identified. Then, using the commercially available image editing software "Photoshop (registered trademark)," each of the identified structures is surrounded, the number of pixels (px) within the surrounded area is calculated, and the px numbers for each structure are summed to determine the total px number of intermetallic compounds within the field of view. The resulting total px number is then converted to an area to calculate the area distribution of the intermetallic compounds. In this embodiment, the same operation as above is performed on 20 fields of view. That is, 20 different fields of view are randomly selected on the cross section of the plating layer, and the area ratio of intermetallic compounds in each field of view is determined using the above method. The average of these values ​​is taken as the area ratio of the metal compounds in the plating layer.

[0056] Next, a method for confirming the presence of Sr-containing intermetallic compounds in the plating layer according to this embodiment will be described.

[0057] The method for analyzing the components in the depth direction inside the plating layer is preferably glow discharge optical emission spectroscopy (GDS) using a glow discharge optical emission spectrometer. In this embodiment, a LECO Japan 850A glow discharge optical emission spectrometer is used, but the measurement device is not limited to this. Furthermore, when analyzing the depth direction, it is preferable to perform the analysis while performing Ar sputtering, and the analysis conditions are argon pressure: 0.27 MPa, output power: 30 W, output voltage: 1000 V, and discharge area: within a circular area with a diameter of 4 mm. Elemental analysis using GDS is carried out from the surface of the coating layer in the depth direction until the Fe concentration reaches 100% (reaching the base steel). Therefore, the analysis range of depth direction analysis using GDS is from the coating surface to the Zn-Al-Mg coating layer, the Al-Fe alloy layer, and part of the steel material. After GDS analysis, the sputter depth of the cross section is measured using a Surfcom130A manufactured by Tokyo Seimitsu Co., Ltd. Elemental analysis using GDS provides an elemental distribution profile in the depth direction of the coating layer. The elemental distribution profile shows the distribution of the content of each element in the depth direction, assuming the total amount of detected elements to be 100%.

[0058] In the present embodiment, in an element distribution profile obtained by qualitative analysis by GDS from the surface of the coating layer toward the steel material, when the thickness of the coating layer is defined as t, the average value of the qualitative analysis value of Sr from the surface of the coating layer to 0.05t is defined as Sr(surf), the qualitative analysis value in the range of 0.05t to 0.66t starting from the surface of the coating layer is defined as Sr(centre), and the qualitative analysis value in the range of more than 0.66t and t starting from the surface of the coating layer is defined as Sr(deep), the following formula (1) is satisfied.

[0059] Sr(surf) <Sr(deep)<Sr(centre) …(1)

[0060] By accumulating Sr-based intermetallic compounds in the center of the coating layer so as to satisfy the above (1), workability can be improved and powdering can be avoided even under severe processing conditions. In other words, satisfying formula (1) increases the hardness of the coating layer, improving scratch resistance and improving flat surface corrosion resistance, ensuring a hard coated steel material with good workability and corrosion resistance.

[0061] In this embodiment, in an element distribution profile obtained by qualitatively analyzing the coating layer from the surface toward the steel material by the GDS method, the depth position at which an Fe intensity equivalent to 5% of the maximum Fe intensity is detected is defined as the "interface," and the region up to this interface is defined as the "coating layer."

[0062] FIG. 1 shows an example of the results of depth profile analysis by GDS of the coating layer according to this embodiment. The graph shown in FIG. 1 is an element distribution profile. The boundary between the coating layer and the steel material is determined to be the position where Fe exceeds 5% of its maximum strength, and the region deeper than that position is determined to be the base iron (steel material). For example, in the case of the analysis results shown in FIG. 1, the maximum strength of Fe is 1.5 cps, so the position of 5% of that strength, that is, the position where the strength of Fe is 0.075 cps, is determined to be the boundary between the coating layer and the steel material.

[0063] In order to achieve an appropriate distribution of the Sr-containing intermetallic compounds in the plating layer, it is effective to appropriately control the manufacturing conditions. A suitable manufacturing method will be described later.

[0064] Next, the indexes of Sr-containing intermetallic compounds determined by X-ray diffraction will be explained.

[0065] The plating layer of this embodiment uses Cu-Kα rays, and in the X-ray diffraction pattern of the plating layer surface measured under conditions of an X-ray output of 50 kV and 300 mA, the diffraction intensity of the Zn-Sr based compounds is I(SrZn 13 ), the following formula (2) is satisfied.

[0066] {I(14.48°)+I(32.74°)} / 2×I(12.50°)}>2.0 …(2) In the formula (2), I(n°) is the X-ray diffraction intensity at a diffraction angle of n°, and n is the diffraction angle (2θ) shown in the formula (2).

[0067] FIG. 2 shows an example of an X-ray diffraction pattern of the plating layer according to this embodiment. As shown in FIG. 2, peaks of Zn-Sr-based compounds consisting of Sr-containing intermetallic compounds appear around 14.48° and 32.74°. When the background intensity is I (12.50°), satisfying the above formula (2) results in the formation of intermetallic compounds with excellent corrosion resistance and hardness in the plating layer. As a result, high hardness and corrosion resistance can be achieved while maintaining the plastic deformability of the plating surface and interface.

[0068] [Method of manufacturing hot-dip plated steel] Next, a method for producing the hot-dip plated steel material according to this embodiment will be described. A simple method for forming the above-described coating layer would be to add Sr directly to a Zn-Al-Mg coating bath and then coat the coating. However, this method raises concerns that Sr-based intermetallic compounds may form on the surface or in the vicinity thereof, rather than in the center of the coating layer. Therefore, as an example of a suitable method for producing the hot-dip coated steel material of this embodiment, a method in which Sr is supplied to the coating layer from a pre-coating layer provided on the base sheet for coating will be described below. In this specification, this method of forming a predetermined pre-coating layer on the base sheet for coating and then sequentially coating the base sheet with Zn-Al-Mg hot-dip coating is referred to as a "two-stage coating method."

[0069] First, an Al-Sr pre-plating layer is formed on a base sheet for plating, such as a cold-rolled or hot-rolled steel sheet. The pre-plating method may be hot-dip plating, electroplating, displacement plating, vapor deposition, etc. Furthermore, these pre-plating layers may be heated and alloyed.

[0070] When pre-plating onto the base sheet is performed by hot dip plating, there are no particular restrictions, and the method can be performed by adding Sr to the conditions for forming normal aluminum plating, such as an Al-0.3% Sr bath or an Al-5% Sr bath.

[0071] Next, the base sheet to be plated is heated to 450 to 600°C, preferably to a temperature similar to the temperature of the plating bath described below. This heating may also serve as annealing of the base sheet (hereinafter, this heating may be referred to as pre-annealing). Heating the steel sheet before immersion in the plating bath described below can reduce temperature fluctuations in the plating bath.

[0072] The heated base sheet on which the pre-coating layer has been formed is immersed in a coating bath and then removed. The temperature of the coating bath is preferably 450°C to 600°C. If the coating bath temperature is too low, the reaction between the pre-coating layer and the hot-dip coating bath does not proceed, and Sr cannot be sufficiently supplied to the coating bath. Furthermore, if the coating bath temperature is too low, the coating adhesion of the resulting coated steel material will be poor. Therefore, the bath temperature is preferably 450°C or higher. More preferably, it is 470°C or higher, even more preferably 500°C or higher, and even more preferably 550°C or higher. On the other hand, if the coating bath temperature is too high, Zn will evaporate significantly in the coating bath, making stable operation difficult in practice. Therefore, the bath temperature is preferably 600°C or lower, and more preferably, it is 580°C or lower. Furthermore, in this embodiment, it is preferable to control the temperature when the original sheet is pulled up. That is, by performing appropriate temperature control and cooling control after immersion, Sr is contained in the plating layer, and the desired Sr-based intermetallic compounds can be formed.

[0073] Sr-based intermetallic compounds are an element that easily dissolves in solid solution, because the plating layer contains Mg.

[0074] Furthermore, in order to sufficiently form Zn-Sr-Si compounds and Zn-Al-Sr-Si compounds, it is preferable to set the average cooling rate in the temperature range of 450 to 350°C to 10°C / sec or less. If the average cooling rate in the temperature range of 450 to 350°C exceeds 10°C / sec, Sr and Si may be dispersed uniformly in the thickness direction of the plating layer, and the desired plating layer may not be obtained.

[0075] The cooling conditions in the temperature range below 350°C are not particularly limited, as they do not affect the formation of intermetallic compounds.

[0076] In this way, by appropriately controlling the cooling rate after the plated base sheet is removed from the bath, it is possible to suppress the formation of Sr-based intermetallic compounds on the surface and interface of the plated layer and to adequately disperse the Sr-based intermetallic compounds near the center of the plated layer, thereby achieving high plating hardness, workability, and corrosion resistance while maintaining the plastic deformability of the plated surface and interface.

[0077] Furthermore, when a steel sheet with an Al-Sr pre-plated layer is used as the plating substrate, the traces of the Al-Sr pre-plated layer disappear immediately upon immersion in a Zn-Al-Mg plating bath at about 550°C because the plating bath and the Al-Sr intermetallic compound have a moderate reactivity, and the immersed plating bath and the Al-Sr intermetallic compound can easily blend together, resulting in the formation of the desired plating layer of this embodiment.

[0078] Next, a method for evaluating the performance of hot-dip galvanized steel materials will be described.

[0079] (bending workability) The bending workability of the plated steel material of this embodiment can be evaluated by measuring the amount of powdering (amount of peeling) when the material is bent back after being bent to V-bend 0R to 5R at 60 degrees.

[0080] Specifically, after forming the material using a 2R-60-degree V-shaped die press, it is further bent back into a flat plate using a flat die. After V-shaping, a 24mm wide cellophane tape is pressed against the valley and then pulled away, and a 90mm long section of the cellophane tape is visually inspected. The evaluation criteria are as follows:

[0081] <Evaluation criteria> A: No peeling occurred. B: Peeling occurred partially at points (less than 5% of the processed area). C: There are linear peeled areas (less than 5 to 10% of the processed area). D: There are linear peeled areas (less than 10 to 20% of the processed area). E: Peeling area is almost completely peeled off (more than 20% of the processed area).

[0082] (corrosion resistance) A 2.3 mm thick flat test piece is prepared and the JASO corrosion weight loss is measured after 120 cycles. The evaluation criteria are as follows:

[0083] <Evaluation criteria> E: Corrosion loss: 25g / m 2 If it is more than or equal to: D: Corrosion loss: 20g / m 2 If it is more than or equal to: C: Corrosion loss is 15g / m 2 If it is more than or equal to: B: Corrosion loss is 10g / m 2 If it is more than or equal to: A: Corrosion loss: 5g / m 2 If it is more than or equal to: S: Corrosion loss: 5g / m 2 If it is less than.

[0084] (Hardness) The hardness measured by the Vickers test is used as an index for evaluating the scratch resistance of the plating layer. Specifically, the Vickers hardness of the plating layer surface is measured under a load of 10 gf. The Vickers hardness is the average hardness of 10 points on the plating layer.

[0085] After the plating layer is formed, various chemical conversion treatments and painting treatments may be carried out.

[0086] In the hot-dip plated steel material of this embodiment, a coating may be formed on the plating layer. One or more coatings may be formed. Examples of the type of coating directly on the plating layer include a chromate coating, a phosphate coating, and a chromate-free coating. These coatings can be formed by known methods such as chromate treatment, phosphate treatment, and chromate-free treatment.

[0087] Chromate treatments include electrolytic chromate treatments that form a chromate film by electrolysis, reactive chromate treatments that form a film by utilizing a reaction with the material and then wash away excess treatment solution, and paint-on chromate treatments that apply a treatment solution to the substrate and dry it without rinsing with water to form a film. Any of these treatments may be used.

[0088] Examples of electrolytic chromate treatments include those using chromic acid, silica sol, resin (phosphoric acid, acrylic resin, vinyl ester resin, vinyl acetate acrylic emulsion, carboxylated styrene butadiene latex, diisopropanolamine-modified epoxy resin, etc.), and hard silica.

[0089] Examples of the phosphate treatment include zinc phosphate treatment, zinc calcium phosphate treatment, and manganese phosphate treatment.

[0090] Chromate-free treatments are particularly suitable because they do not place a burden on the environment. Chromate-free treatments include electrolytic chromate-free treatments that form a chromate-free film by electrolysis, reactive chromate-free treatments that form a film by utilizing a reaction with the material and then wash away excess treatment liquid, and paint-on chromate-free treatments that apply a treatment liquid to the substrate and dry it without rinsing with water to form a film. Any of these treatments may be used.

[0091] Furthermore, one or more organic resin coatings may be provided on the coating directly on the plating layer. The organic resin is not limited to a specific type, and examples include polyester resin, polyurethane resin, epoxy resin, acrylic resin, polyolefin resin, and modified versions of these resins. Here, the term "modified version" refers to a resin in which a reactive functional group contained in the structure of these resins is reacted with another compound (such as a monomer or a crosslinking agent) containing a functional group capable of reacting with the functional group.

[0092] Such organic resins may be a mixture of one or more organic resins (unmodified), or a mixture of one or more organic resins obtained by modifying at least one other organic resin in the presence of at least one organic resin. The organic resin film may also contain any coloring pigment or anti-rust pigment. Aqueous solutions prepared by dissolving or dispersing in water may also be used. [Example]

[0093] Next, examples of the present invention will be described, but the conditions in the examples are merely examples adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these examples. Various conditions can be adopted in the present invention as long as they do not deviate from the gist of the present invention and the object of the present invention is achieved.

[0094] First, a cold-rolled steel sheet (SPCC) measuring 100 mm x 200 mm and 0.8 mm thick was prepared as the base sheet for plating. An Al-Sr pre-plating layer as shown in Tables 1A and 1B was formed on the surface of this cold-rolled steel sheet using the Al-Sr-based plating bath shown below. Note that the "two-stage" in the "Manufacturing Method" column in Tables 1A and 1B indicates that the two-stage plating method described above was used. 。

[0095] Al-Sr plating bath: Sr: 0.3 to 10 mass%, bath temperature: 650°C.

[0096] After forming an Al-Sr pre-plating layer on the original sheet for plating, the original sheet for plating was pre-annealed by heating at 550°C for 0.5 to 3.0 minutes.

[0097] The obtained plated substrate was subjected to hot-dip plating using a hot-dip plating simulator. First, alloys having the plating bath components shown in Tables 1A and 1B were prepared by vacuum melting, and plating baths were prepared in a completely oxygen-free, nitrogen-substituted atmosphere (O2 concentration less than 5 ppm). Next, a point on the original plate (the backside of the center of the evaluation surface) was spot-welded to a K-type thermocouple to determine the temperature history until the plating solidified. The plated steel sheet was heated to the specified temperature in a H2 (25%)-N2 atmosphere. The plating bath temperature was set to 550°C, and the plated substrate was immersed at a speed of 600 mm / s, held in the bath for 3 seconds, and then lifted at a speed of 600 mm / s. Immediately after lifting, the plating thickness was adjusted to 40 μm using N2 wiping gas, and then the workpiece was cooled at the average cooling rate shown in Table 1 by blowing N2 gas at a controlled flow rate in an oxygen-free, nitrogen-substituted atmosphere. Through the above steps, a plated steel sheet was obtained.

[0098] Next, evaluation samples were cut from each type of plated steel sheet. Samples for GDS analysis and SEM observation were cut out at 30 mm square locations on the opposite side of the thermocouple. Corrosion samples, measuring 100 x 50 mm, were taken from the center of the plated steel sheet.

[0099] The cut samples were evaluated by bending tests, Vickers hardness measurements, and SST corrosion tests. The Fe content of the plating layer is not listed in the table, but it was in the range of 0 to 5% in all cases. The evaluation results, the composition of the plating layer, the GDS analysis results, the X-ray diffraction (XRD) results, the area ratios of the Zn-Sr-Si compounds and the Zn-Al-Sr-Si compounds, etc. are shown in Tables 2A and 2B. Note that underlines in each table indicate that the results are outside the scope of the present invention, that the preferred manufacturing conditions are not met, or that the characteristic values ​​are unfavorable. Comparative example No. 30 In No. 1, the temperature of the plating bath was low, so the reaction between the Al-Sr pre-plating layer and the plating bath did not proceed sufficiently. As a result, the Al-Sr pre-plating layer remained between the base sheet and the plating layer, and suitable hot-dip plated steel could not be obtained. 30 The plating adhesion of the plated steel material in (2) deteriorated, so the GDS analysis results, X-ray diffraction (XRD) and other performance characteristics could not be properly evaluated (indicated as "-" in the table).

[0100] [Table 1A]

[0101] [Table 1B]

[0102] [Table 2A]

[0103] [Table 2B] [Industrial Applicability]

[0104] According to the above-described aspects of the present invention, a hot-dip plated steel material having excellent coating hardness, corrosion resistance, and workability can be obtained. Therefore, the obtained hot-dip plated steel material can be suitably applied to the fields of automobiles, building materials, etc., and therefore has high industrial applicability.

Claims

1. Steel and A plating layer disposed on a surface of the steel material; A hot-dip galvanized steel material having the following properties: The plating layer comprises, in mass %, Al: more than 10.0% and less than 45.0%; Mg: 4.0% or more, 15.0% or less, Si: 0.05% or more, 2.0% or less, Sr: 0.03% or more, 1.50% or less and further comprising Sn: 0% or more, 0.7% or less, Bi: 0% or more, 0.3% or less, In: 0% or more, 0.3% or less, Ca: 0% or more, 0.6% or less, Y: 0% or more, 0.3% or less, La: 0% or more, 0.3% or less, Ce: 0% or more, 0.3% or less, Li: 0% or more, 0.3% or less, Ni: 0% or more, 1.0% or less, Cu: 0% or more, 1.0% or less, Ag: 0% or more, 0.25% or less, Sb: 0% or more, 0.25% or less, Pb: 0% or more, 0.25% or less, B: 0% or more, 0.5% or less, P: 0% or more, 0.5% or less, Ti: 0% or more, 0.25% or less, Co: 0% or more, 0.25% or less, V: 0% or more, 0.25% or less, Nb: 0% or more, 0.25% or less, Mn: 0% or more, 0.25% or less, Zr: 0% or more, 0.25% or less, W: 0% or more, 0.25% or less, Fe: 0% or more, 5.0% or less, The balance has a chemical composition including Zn and impurities, the plating layer contains a Zn—Sr-based compound, a Zn—Sr—Si-based compound, and a Zn—Al—Sr—Si-based compound; The plating layer contains the Zn-Sr-Si compound and the Zn-Al-Sr-Si compound in a total area ratio of 5% to 30% in a cross section along a thickness direction of the plating layer, In an element distribution profile obtained by performing a qualitative analysis by glow discharge optical emission spectrometry from the surface of the plating layer toward the steel material, when the thickness of the plating layer is t, the average value of the qualitative analysis value of Sr from the surface of the plating layer to 0.05t is Sr(surf), the qualitative analysis value in the range from 0.05t to 0.66t starting from the surface of the plating layer is Sr(centre), and the qualitative analysis value in the range from 0.66t to t starting from the surface of the plating layer is Sr(deep), the following formula (1) is satisfied: Hot-dip galvanized steel. Sr(surf)<Sr(deep)<Sr(centre)…(1)

2. In the chemical composition of the plating layer, Sr: 0.10% or more, 1.50% or less and The X-ray diffraction pattern of the surface of the plating layer was measured using Cu-Kα rays under conditions of an X-ray output of 50 kV and 300 mA. The diffraction intensity of the Zn-Sr compound was determined as I (SrZn １３ 2. The hot-dip plated steel material according to claim 1 , which satisfies the following formula (2): {I(14.48°)+I(32.74°)} / 2×I(12.50°)}>2.0...(2) In equation (2), I(n°) is the X-ray diffraction intensity at a diffraction angle of n°, where n is the diffraction angle (2θ) shown in equation (2).

3. In the chemical composition of the plating layer, Si: 0.05% or more, 0.5% or less The hot-dip plated steel material according to claim 1 or 2.

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