Plated Steel

Abstract

This plated steel product comprises a steel product and a plating layer disposed on a surface of the steel product, The plating layer has a predetermined chemical composition, and the diffraction intensity obtained from an X-ray diffraction measurement of the plating layer satisfies a predetermined relational expression.

Description

[Technical field]

[0001] The present invention relates to a plated steel material. This application claims priority based on Japanese Patent Application No. 2023-064064, filed on April 11, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] Steel materials having a Zn-plated layer containing Al and Mg formed on the surface (Zn-Al-Mg-plated steel materials) have excellent corrosion resistance, and therefore are widely used as materials for structural members such as building materials that require corrosion resistance.

[0003] For example, Patent Document 1 describes a plated steel sheet comprising a steel sheet and a plating layer formed on the surface of the steel sheet, the plating layer containing, in average composition, 0-90 mass% Al, 0-10 mass% Mg, with the remainder containing Zn and impurities, the plating layer having a patterned portion and a non-patterned portion arranged to have a predetermined shape, the patterned portion and the non-patterned portion each including one or two of a first region and a second region, the absolute value of the difference between the area ratio of the first region in the patterned portion and the area ratio of the first region in the non-patterned portion being 30% or more, the first region being a region having an orientation ratio of 3.5 or more, and the second region being a region having an orientation ratio of less than 3.5.

[0004] Patent Document 2 describes a Zn-Al-Mg plated steel sheet which includes a steel sheet and a plating layer containing 4 mass% or more and 22 mass% or less of Al, 1 mass% or more and 5 mass% or less of Mg, with the balance containing Zn and unavoidable impurities, and in a cross section of the plating layer parallel to the surface of the plating layer, a diffraction intensity ratio I(200) / I(111), which is 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 of the Al phase, is 0.8 or more.

[0005] Incidentally, plated steel products are placed in a variety of environments, and in areas where volcanic gas is generated or industrial areas, SOx gas in the atmosphere dissolves in rainwater and turns into acid rain, which can affect the corrosion resistance of plated steel products. However, in the prior art, little consideration has been given to improving corrosion resistance in acidic environments.

[0006] Patent Document 1 discloses the diffraction peak intensity I 0002 and (10-11) plane diffraction peak intensity I 10-11 When the area where the intensity ratio is 3.5 or more is defined as the first area, and the area where the intensity ratio is less than 3.5 is defined as the second area, it is said that by making the difference between the area ratio of the first area in the patterned portion and the area ratio of the first area in the non-patterned portion 30% or more, it is possible to intentionally make characters, designs, etc. appear on the surface of the plating layer, but the corrosion resistance in acidic environments has not been examined.

[0007] In Patent Document 2, the orientation of the Al phase in the plating layer is controlled to give the plating layer a fine-grained, smooth, pear-skin appearance with many shiny parts, but corrosion resistance in an acidic environment is not considered. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2021-85086 [Patent Document 2] International Publication No. 2011 / 001662 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plated steel material that is excellent in sacrificial corrosion resistance and corrosion resistance in acidic environments. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention employs the following configuration. [1] Steel; A plating layer on the steel material; The chemical composition of the plating layer is, in mass%, Al: 6.0-30.0%, Mg: 3.0-15.0%, Fe: 0.01-15.00%, Si: 0-2.0%, Ca: 0-2.00% Sb:0~0.50%, Pb:0~0.50%, Cu:0~1.00%, Sn:0~1.00%, Ti:0~1.00%, Cr:0~1.00%, Nb:0~1.00%, Z r:0~1.00%, Ni:0~1.000%, Mn:0~1.00%, Mo:0~1.00%, Ag:0~1.00%, Li:0~1.00%, La:0~1.000%, C Contains one or more elements selected from the group consisting of e: 0-1.000%, B: 0-0.500%, Y: 0-0.50%, P: 0-0.50%, Sr: 0-0.50%, Co: 0-0.500%, Bi: 0-0.500%, In: 0-0.50%, V: 0-0.500%, and W: 0-0.50%, and the total content of these elements is 0-5.0%, The balance is composed of Zn and impurities. A plated steel material, wherein the diffraction intensity obtained from an X-ray diffraction measurement of the plating layer satisfies the following formula (1): 0.5≦I(002) Zn / {I(100) Zn +I(101) Zn}≦25.0 …(1) However, I(002) in formula (1) Zn is the diffraction intensity of (002) of the η-Zn phase, and I(100) Zn is the diffraction intensity of (100) of the η-Zn phase, and I(101) Zn is the diffraction intensity of (101) of the η-Zn phase. [2] The plated steel material according to [1], wherein the Al and Mg content of the plated layer is Al: 10.0 to 25.0%, and Mg: 4.5 to 15.0%, respectively. [3] The plated steel material according to [1] or [2], wherein the Al and Mg content of the plated layer is Al: 15.0 to 22.0%, and Mg: 5.5 to 15.0%, respectively. [4] The plated steel material according to any one of [1] to [3], wherein the diffraction intensity obtained from an X-ray diffraction measurement of the plated layer satisfies the following formula (2): 1.5≦I(002) Zn / {I(100) Zn +I(101) Zn}≦25.0 …(2) [5] The plated steel material according to any one of [1] to [4], wherein the area ratio of the [α / MgZn2 eutectic structure] contained in the surface structure when the plated layer is viewed in a plane is 5 to 70%. [6] The plated steel material according to any one of [1] to [5], wherein the area ratio of the [α / MgZn2 eutectic structure] contained in the surface structure when the plated layer is viewed in a plane is 10 to 70%. [7] The Sn content of the plating layer is, by mass%, Sn: 0.05 to 0.50%, The plated steel material according to any one of [1] to [6], wherein an Mg2Sn phase is detected by X-ray diffraction measurement of the plated layer. [8] The plated steel material according to any one of [1] to [7], containing one or both of La and Ce in a total amount of 0.005 to 0.500%. Effect of the Invention

[0011] According to the present invention, a plated steel material having excellent corrosion resistance in an acidic environment can be provided. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional schematic diagram of a plated steel material according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] For the corrosion resistance of plated steel in acidic environments, it is necessary to form a plating layer on the surface of the steel that has excellent corrosion resistance against acidic environments such as acid rain. To improve the corrosion resistance of the plating layer in acidic environments, it is required that the elements that make up the plating layer are not easily eluted even in acidic environments.

[0014] Therefore, the present inventors have conducted extensive research to improve the acidic environment corrosion resistance of the Zn plating layer containing Al and Mg. The η-Zn phase contained in the plating layer has a hexagonal crystal structure, which includes various crystal orientation planes. The corrosion resistance of these crystal orientation planes is not uniform across all orientation planes. For example, the (002) plane of the η-Zn phase is a dense crystal orientation plane with a relatively high Zn atomic density, so Zn itself is relatively difficult to dissolve, and the corrosion resistance of Zn itself is considered to be relatively high. On the other hand, the (100) plane of the η-Zn phase is a crystal orientation plane with a lower Zn atomic density than the (002) plane, so Zn itself is relatively easy to dissolve, and although the corrosion resistance of Zn itself is low, the base steel is protected from corrosion by the corrosion products generated by the corrosion of Zn, so the sacrificial corrosion protection against the base steel is considered to be high. Therefore, it was thought that the acidic environment corrosion resistance of the Zn plating layer containing Al and Mg could be improved by orienting the (002) plane of the η-Zn phase parallel to the surface of the plating layer.

[0015] Therefore, the present inventors have attempted to orient the (002) plane of the η-Zn phase contained in the coating layer parallel to the surface of the coating layer. When a Zn coating layer containing Al and Mg solidifies from a molten state, the α phase first crystallizes, followed by the MgZn2 phase and the η-Zn phase, and then a ternary eutectic structure containing the α phase, the MgZn2 phase, and the η-Zn phase is formed. The ternary eutectic temperature, which is a guide for the start of formation of the ternary eutectic structure, can be roughly predicted based on the chemical composition of the coating layer. It has been found that when a eutectic reaction is caused to occur at a temperature lower than the predicted ternary eutectic temperature, the (002) plane of the η-Zn phase in the ternary eutectic structure is oriented parallel to the surface of the coating layer. Specifically, it has been found that by adjusting the immersion temperature when the steel material is immersed in the coating bath and the cooling conditions after the steel material is pulled out of the coating bath, a eutectic reaction is caused to occur at a temperature lower than the predicted ternary eutectic temperature, and the (002) plane of the η-Zn phase can be oriented parallel to the surface of the coating layer.

[0016] Hereinafter, a plated steel material according to an embodiment of the present invention will be described. The plated steel material according to this embodiment includes a steel material and a plated layer disposed on the surface of the steel material, and the chemical composition of the plated layer contains, in mass%, Al: 6.0-30.0%, Mg: 3.0-15.0%, Fe: 0.01-15.00%, Si: 0-2.0%, Ca: 0-2.00%, Sb: 0-0.50%, Pb: 0-0.50%, Cu: 0-1.00%, Sn: 0-1.00%, Ti: 0-1.00%, Cr: 0-1.00%, Nb: 0-1.00%, Zr: 0-1.00%, Ni: 0-1.000%, Mn: 0-1.00%, Mo: 0-1.00%, Ag: 0-1. The plated steel material contains one or more elements selected from the group consisting of Eu: 0.00%, Li: 0-1.00%, La: 0-1.000%, Ce: 0-1.000%, B: 0-0.500%, Y: 0-0.50%, P: 0-0.50%, Sr: 0-0.50%, Co: 0-0.500%, Bi: 0-0.500%, In: 0-0.50%, V: 0-0.500%, and W: 0-0.50%, with the total content of these elements being 0-5.0%, and the balance being Zn and impurities, and the diffraction intensity obtained from the X-ray diffraction measurement of the plated layer satisfies the following formula (1). The surface of the steel material referred to here means the interface between the plated layer and the steel material.

[0017] 0.5≦I(002) Zn / {I(100) Zn +I(101) Zn}≦25.0 …(1)

[0018] However, I(002) in formula (1) Zn is the diffraction intensity of (002) of the η-Zn phase, and I(100) Zn is the diffraction intensity of (100) of the η-Zn phase, and I(101) Zn is the diffraction intensity of (101) of the η-Zn phase.

[0019] In the following description, the "%" of the content of each element in the chemical composition means "mass %". The content of an element in the chemical composition may be expressed as element concentration (e.g., Zn concentration, Mg concentration, etc.). "Corrosion resistance in acidic environments" refers to the property of a plating layer (specifically, a Zn-Al-Mg alloy layer) being resistant to corrosion in an acidic environment. "Plane corrosion resistance" refers to the property of the plating layer (specifically, a Zn-Al-Mg alloy layer) itself being resistant to corrosion. "Sacrificial corrosion resistance" refers to the property of suppressing corrosion of the steel material at exposed parts (e.g., cut end faces of a plated steel material, cracked parts of the plating layer during processing, and parts where the steel material is exposed due to peeling of the plating layer). "Plating layer" refers to a plating film produced by so-called hot-dip plating processing.

[0020] As shown in Fig. 1, the plated steel material 1 according to this embodiment has a steel material 11. There is no particular limitation on the shape of the steel material 11, and an example of the steel material 11 is a steel plate. The steel material 11 may also be a formed base steel material such as a steel pipe, a civil engineering and construction material (a fence, a corrugated pipe, a drainage ditch cover, a sand-flying prevention plate, a bolt, a wire mesh, a guard rail, a water cut-off wall, etc.), a home appliance part (a housing for an outdoor unit of an air conditioner, etc.), or an automobile part (a chassis part, etc.). The forming process is, for example, various plastic processing techniques such as pressing, roll forming, and bending.

[0021] There is no particular limitation on the material of the steel material 11. The steel material 11 can be various steel materials such as general steel, Al-killed steel, extra-low carbon steel, high carbon steel, various high tensile steels, some high alloy steels (steels containing strengthening elements such as Ni, Cr, etc.). The steel material 11 may be a hot-rolled steel sheet, a hot-rolled steel strip, a cold-rolled steel sheet, a cold-rolled steel strip, etc. described in JIS G 3302:2010. There is also no particular limitation on the manufacturing method of the steel sheet (hot rolling method, pickling method, cold rolling method, etc.) and the specific manufacturing conditions thereof.

[0022] Furthermore, the steel material 11 serving as the original sheet for plating may be a pre-plated steel material in which the surface of the steel material 11 is pre-plated. An example of the pre-plated steel material is Ni pre-plated steel material having Ni plating on the steel material 11. The pre-plated steel material is obtained, for example, by electrolytic treatment or displacement plating. The electrolytic treatment is performed by immersing the base steel material in a sulfate bath or chloride bath containing metal ions of various pre-plating components and performing electrolytic treatment. The displacement plating is performed by immersing the base steel material in an aqueous solution containing metal ions of various pre-plating components and having a pH adjusted with sulfuric acid, thereby displacing and precipitating the metal.

[0023] The plated steel material 1 according to this embodiment has a plated layer 12 on a steel material 11. The plated layer 12 of the plated steel material 1 according to this embodiment is mainly composed of a Zn-Al-Mg alloy layer due to the chemical composition described later. The plated layer 12 of the plated steel material 1 according to this embodiment may also include an Fe-Al-based interfacial alloy layer between the steel material 11 and the Zn-Al-Mg alloy layer. That is, the plated layer 12 may have a single-layer structure of a Zn-Al-Mg alloy layer, or may have a laminated structure including a Zn-Al-Mg alloy layer and an Fe-Al-based interfacial alloy layer. The Fe-Al-based interfacial alloy layer may also contain Ni.

[0024] The chemical composition of the plating layer according to this embodiment is composed of Zn and other alloying elements. The chemical composition of the plating layer will be described in detail below. Note that elements with a lower limit of 0% are not essential for solving the problems of the plated steel material according to this embodiment, but are optional elements that are allowed to be included in the plating layer for the purpose of improving characteristics, etc.

[0025] <Al:6.0~30.0%> Al forms an α-phase solid solution with Zn, and contributes to improving flat corrosion resistance, acidic environment corrosion resistance, and sacrificial corrosion protection. Therefore, the Al concentration is set to 6.0% or more. The Al concentration may be set to 10.0% or more, 12.0% or more, or 15.0% or more. On the other hand, if Al is excessive, the Mg concentration and Zn concentration are relatively decreased, and the sacrificial corrosion protection is deteriorated. Therefore, the Al concentration is set to 30.0% or less. The Al concentration may be set to 28.0% or less, 25.0% or less, 22.0% or less, or 20.0% or less.

[0026] <Mg:3.0~15.0%> Mg is an essential element for ensuring flat surface corrosion resistance, acidic environment corrosion resistance, and sacrificial corrosion resistance. Therefore, the Mg concentration is set to 3.0% or more. The Mg concentration may be set to 4.5% or more, 5.5% or more, or 6.0% or more. On the other hand, if the Mg concentration is excessive, the workability, particularly the powdering property, may deteriorate, and further the flat surface corrosion resistance may deteriorate. Therefore, the Mg concentration is set to 15.0% or less. The Mg concentration may be set to 12.0% or less, 10.0% or less, or 8.0% or less.

[0027] <Fe:0.01%~15.00%> The plating layer may contain 0.01% or more of Fe. It has been confirmed that the performance of the plating layer is not adversely affected if the Fe concentration is 15.00% or less. The Fe concentration may be, for example, 0.05% or more, 0.10% or more, 0.50% or more, or 1.00% or more. The Fe concentration may be, for example, 10.00% or less, 5.00% or less, 2.00% or less, or 1.00% or less. Since Fe may be mixed in from the steel material, the Fe concentration may be 0.05% or more.

[0028] <Si:0%~2.0%> The Si concentration may be 0%. On the other hand, Si contributes to improving the corrosion resistance of the flat surface and the corrosion resistance in an acidic environment. Therefore, the Si concentration may be 0.05% or more, 0.1% or more, 0.2% or more, or 0.5% or more. On the other hand, if the Si concentration is excessive, the corrosion resistance of the flat surface, the corrosion resistance in an acidic environment, and the sacrificial corrosion protection are deteriorated. Therefore, the Si concentration is set to 2.0% or less. The Si concentration may be 1.5% or less, 1.0% or less, or 0.5% or less.

[0029] <Ca:0%~2.00%> The Ca concentration may be 0%. On the other hand, Ca is an element that can adjust the amount of Mg elution that is optimal for imparting flat surface corrosion resistance and acidic environment corrosion resistance. Therefore, the Ca concentration may be 0.05% or more, 0.10% or more, or 0.50% or more. On the other hand, if the Ca concentration is excessive, the flat surface corrosion resistance and workability will deteriorate. Therefore, the Ca concentration is set to 2.00% or less. The Ca concentration may be 1.00% or less, 0.50% or less, or 0.10% or less.

[0030] Furthermore, the plating layer according to this embodiment contains Sb: 0 to 0.50%, Pb: 0 to 0.50%, Cu: 0 to 1.00%, Sn: 0 to 1.00%, Ti: 0 to 1.00%, Cr: 0 to 1.00%, Nb: 0 to 1.00%, Zr: 0 to 1.00%, Ni: 0 to 1.000%, Mn: 0 to 1.00%, Mo: 0 to 1.00%, Ag: 0 to 1.00%, Li: 0 to One or more elements selected from the group consisting of 1.00%, La: 0-1.000%, Ce: 0-1.000%, B: 0-0.500%, Y: 0-0.50%, P: 0-0.50%, Sr: 0-0.50%, Co: 0-0.500%, Bi: 0-0.500%, In: 0-0.50%, V: 0-0.500%, and W: 0-0.50% may be contained. The total of these elements is 0-5.0%. If the total exceeds 5.0%, the flat corrosion resistance, red rust resistance, and base steel corrosion resistance may decrease. In addition, since these elements are optional addition elements, the total amount may be 0%.

[0031] <Sb、Pb:それぞれ0~0.50%> The concentrations of Sb and Pb may be 0%. On the other hand, Sb and Pb contribute to improving sacrificial corrosion protection. Therefore, the concentrations of Sb and Pb may be 0.05% or more, 0.10% or more, or 0.15% or more. On the other hand, if the concentrations of Sb and Pb are excessive, the corrosion resistance of the flat surface portion deteriorates. Therefore, the concentrations of Sb and Pb are 0.50% or less. The concentrations of Sb and Pb may be 0.40% or less, 0.30% or less, or 0.25% or less.

[0032] <Cu、Ti、Cr、Nb、Zr、Mn、Mo、AgおよびLi:それぞれ0~1.00%> The concentrations of Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag and Li may each be 0%. On the other hand, these contribute to improving sacrificial corrosion resistance. Therefore, the concentrations of Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag and Li may each be 0.05% or more, 0.08% or more, or 0.10% or more. On the other hand, if the concentrations of Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag and Li are excessive, the corrosion resistance of the flat surface portion deteriorates. Therefore, the concentrations of Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag and Li are each 1.00% or less. The concentrations of Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag and Li may each be 0.80% or less, 0.70% or less, or 0.60% or less.

[0033] <Ni:0~1.000%> The Ni concentration may be 0%. On the other hand, these contribute to improving sacrificial corrosion resistance. Therefore, the Ni concentration may be 0.050% or more, 0.080% or more, or 0.100% or more. On the other hand, if the Ni concentration is excessive, the corrosion resistance of the flat surface portion deteriorates. Therefore, the Ni concentration is 1.000% or less. The Ni concentration may be 0.800% or less, 0.700% or less, or 0.600% or less.

[0034] <Sn:0~1.00%> The Sn concentration may be 0%. On the other hand, Sn is an element that forms an intermetallic compound with Mg and improves the sacrificial corrosion resistance of the plating layer. Therefore, the Sn concentration may be 0.01% or more, 0.05% or more, or 0.10% or more. However, if the Sn concentration is excessive, the planar corrosion resistance deteriorates. Therefore, the Sn concentration is set to 1.00% or less. The Sn concentration may be 0.50% or less, 0.30% or less, or 0.20% or less.

[0035] <La、Ce:それぞれ0~1.000%> The concentrations of La and Ce may each be 0%. On the other hand, La and Ce contribute to improving sacrificial corrosion protection. Therefore, the concentrations of La and Ce may each be 0.100% or more, 0.150% or more, or 0.200% or more. On the other hand, if the concentrations of La and Ce are excessive, the corrosion resistance of the flat surface portion deteriorates. Therefore, the concentrations of La and Ce are each 1.000% or less. The concentrations of La and Ce may each be 0.500% or less. Also, the total of one or two of La and Ce may be 0.010 to 0.500%.

[0036] <B:0~0.500%> The concentration of B may be 0%. On the other hand, B contributes to improving sacrificial corrosion protection. Therefore, the concentration of B may be 0.100% or more, 0.150% or more, or 0.200% or more. On the other hand, if the concentration of B is excessive, the corrosion resistance of the flat surface portion deteriorates. Therefore, the concentration of B is set to 0.500% or less. The concentration of B may be set to 0.400% or less, or 0.300% or less.

[0037] <Y、PおよびSr:それぞれ0~0.50%> The concentrations of Y, P and Sr may each be 0%. On the other hand, Y, P and Sr contribute to improving sacrificial corrosion resistance. Therefore, the concentrations of Y, P and Sr may each be 0.10% or more, 0.15% or more, or 0.20% or more. On the other hand, if the concentrations of Y, P and Sr are excessive, the corrosion resistance of the flat surface portion deteriorates. Therefore, the concentrations of Y, P and Sr are each set to 0.50% or less. The concentrations of Y, P and Sr may each be set to 0.40% or less, or 0.30% or less.

[0038] <Co、Bi、V:それぞれ0~0.500%> The concentrations of Co, Bi, and V may be 0%. On the other hand, Co, Bi, and V contribute to improving sacrificial corrosion resistance. Therefore, the concentrations of Co, Bi, and V may be 0.100% or more, 0.150% or more, or 0.200% or more. On the other hand, if the concentrations of Co, Bi, and V are excessive, the corrosion resistance of the flat surface portion deteriorates. Therefore, the concentrations of Co, Bi, and V are 0.500% or less. The concentrations of Co, Bi, and V may be 0.400% or less, or 0.300% or less.

[0039] <In、W:それぞれ0~0.50%> The respective concentrations of In and W may be 0%. On the other hand, In and W contribute to improving sacrificial corrosion protection. Therefore, the respective concentrations of In and W may be 0.10% or more, 0.15% or more, or 0.20% or more. On the other hand, if the concentrations of In and W are excessive, the corrosion resistance of the flat surface portion deteriorates. Therefore, the respective concentrations of In and W are set to 0.50% or less. The respective concentrations of In and W may be set to 0.40% or less, or 0.30% or less.

[0040] <Balance: Zn and impurities> The remainder of the components of the plating layer according to this embodiment are Zn and impurities. Zn is an element that provides the plating layer with flat corrosion resistance, acidic environment corrosion resistance, and sacrificial corrosion protection. In this embodiment, impurities refer to those that are mixed in from the manufacturing environment, etc., and those that are acceptable within a range that does not adversely affect the properties of the plated steel material according to this embodiment. For example, trace amounts of components other than Fe may be mixed into the plating layer as impurities due to mutual atomic diffusion between the base steel material and the plating bath.

[0041] The chemical composition of the plating layer is measured by the following method. For example, the plated steel is cut into a size of 30 mm x 30 mm to obtain a measurement sample. Next, an acid solution is obtained by peeling and dissolving the plating layer of the measurement sample using a 10% hydrochloric acid solution containing 0.06 mass % of an inhibitor (Ibit 710K, manufactured by Asahi Chemical Industry Co., Ltd.) that suppresses corrosion of steel. Next, the obtained acid solution is subjected to ICP analysis. This allows the chemical composition of the plating layer to be obtained. Note that when cutting the plated steel, it is preferable to avoid the ends and welds of the plated steel. There is no particular restriction on the type of acid as long as it is an acid that can dissolve the plating layer. For example, 10% by volume of HCl is used. Note that the chemical composition is measured three times by the above-mentioned means, and the average of the measurements is taken as the chemical composition of the plating layer.

[0042] Next, the metal structure of the plating layer will be described.

[0043] The plating layer contains an α phase and an MgZn2 phase. The α phase is a phase containing a fine Al phase and a fine Zn phase. The α phase and the MgZn2 phase may partially form a lamellar binary eutectic structure (α phase / MgZn2 eutectic structure). When the α phase / MgZn2 eutectic structure is contained, the corrosion resistance of the flat surface of the plating layer is further improved. However, when the α phase and the MgZn2 phase are excessively precipitated and the plating layer contains a large amount of the α phase / MgZn2 eutectic structure, the proportion of the η-Zn phase becomes relatively small, and the red rust resistance and the corrosion resistance of the base steel are reduced. Therefore, the area ratio of the α phase / MgZn2 eutectic structure is preferably in the range of 70% or less, preferably in the range of 5 to 70%, and may be 10 to 70%. The α phase / MgZn2 eutectic structure may be 0% or more than 0%.

[0044] The coating layer of the present embodiment contains an η-Zn phase in addition to the α phase and the MgZn2 phase. At least a part of the η-Zn phase forms a ternary eutectic structure together with the α phase and the MgZn2 phase. The η-Zn phase may be contained in the coating layer as a massive η-Zn phase.

[0045] Furthermore, when the plating layer contains 0.05 to 0.5% Sn, the plating layer definitely contains the Mg2Sn phase. The Mg2Sn phase may be contained even when the Sn content is 0.05% or less. Since the amount of the Mg2Sn phase is small, its presence can be confirmed by X-ray diffraction measurement. The inclusion of the Mg2Sn phase in the plating layer further improves the sacrificial corrosion protection of the plated steel material.

[0046] X-ray diffraction measurements are performed using Kα radiation from a Cu tube, and if a peak is detected at 23.4±0.3°, it is determined that the Mg2Sn phase is present. X-ray diffraction measurements are performed using an X-ray diffractometer (Rigaku, model number RINT-TTR III) with an X-ray output of 50 kV, 300 mA, copper target, goniometer TTR (horizontal goniometer), Kβ filter slit width of 0.05 mm, longitudinal limiting slit width of 2 mm, receiving slit width of 8 mm, and receiving slit 2 open, with a scan speed of 5 deg. / min, step width of 0.01 deg, and scan axis 2θ (5 to 90°).

[0047] The plating layer may contain other phases as the balance, such as an Al-Ca-Si phase.

[0048] Next, the crystal orientation of the η-Zn phase will be described. In the plating layer of this embodiment, the X-ray diffraction intensity obtained from the X-ray diffraction measurement of the plating layer must satisfy the relationship of the following formula (1). When the following formula (1) is satisfied, the (002) plane of the η-Zn phase is oriented parallel to the surface of the plating layer, improving the corrosion resistance in an acidic environment. It is more preferable that the following formula (2) is satisfied. I(002) Zn / {I(100) Zn +I(101) Zn When the ratio of I(002) to I(003) is less than 0.5, the orientation of the (002) plane of the η-Zn phase is insufficient, and the corrosion resistance in an acidic environment is insufficient. Zn / {I(100) Zn +I(101) Zn If the value of} exceeds 25.0, the sacrificial corrosion protection properties may decrease.

[0049] 0.5≦I(002) Zn / {I(100) Zn +I(101) Zn}≦25.0 …(1)

[0050] 1.5≦I(002) Zn / {I(100) Zn +I(101) Zn}≦25.0 …(2)

[0051] However, I(002) in formula (1) and formula (2) Zn is the diffraction intensity of (002) of the η-Zn phase, and I(100) Zn is the diffraction intensity of (100) of the η-Zn phase, and I(101) Zn is the diffraction intensity of (101) of the η-Zn phase.

[0052] The method for measuring the area ratio of the [α-phase / MgZn2 eutectic structure] is as follows. First, the surface of the plating layer is adjusted to be flat by mechanical polishing. Next, the surface of the plating layer is chemically polished by colloidal polishing until it becomes a mirror surface. The surface of the plated layer after polishing is observed with an SEM. Specifically, an element distribution image is taken using SEM-EDS at a magnification of 5000 times (area of ​​200 μm vertical and 200 μm horizontal). In this element distribution image, the phase in which Mg and Zn coexist is identified as the MgZn2 phase. Also, the phase containing Al and Zn is identified as the α phase. Most of the α phase exhibits a dendritic morphology. Then, after identifying the [α phase / MgZn2 eutectic structure] containing the α phase and the MgZn2 phase, the area ratio of the [α phase / MgZn2 eutectic structure] contained in the field of view is calculated by binarization using image analysis software.

[0053] I(002) in formula (1) and formula (2) Zn / {I(100) Zn +I(101) ZnThe measurement method of} is as follows: First, the surface of the plating layer is mechanically polished, and if necessary, chemically polished to make the surface of the plating layer into a mirror-like state. Next, for example, an X-ray diffraction measurement is performed using an X-ray diffractometer (Rigaku Corporation (Model RINT-TTR III)) with an X-ray output of 50 kV, 300 mA, a copper target, a goniometer TTR (horizontal goniometer), a Kβ filter slit width of 0.05 mm, a longitudinal limiting slit width of 2 mm, a receiving slit width of 8 mm, and a receiving slit 2 open, and with measurement conditions of a scan speed of 5 deg. / min, a step width of 0.01 deg, and a scan axis 2θ (5 to 90°). Then, the diffraction intensity of the (100) plane of the η-Zn phase (maximum intensity in the range of 38.993 ± 0.2°), the diffraction intensity of the (002) plane (maximum intensity in the range of 36.297 ± 0.2°), and the diffraction intensity of the (101) plane (maximum intensity in the range of 43.232 ± 0.2°) are measured. The diffraction intensity is the intensity excluding the background intensity. From the obtained diffraction intensities, the I(002) Zn / {I(100) Zn +I(101) Zn} is required.

[0054] Whether or not the plating layer contains an Mg2Sn phase is determined by whether or not a diffraction peak specific to Mg2Sn appears when the above-mentioned X-ray diffraction measurement is performed.

[0055] The coating weight per side of the plating layer is, for example, 20 to 300 g / m 2 The amount of adhesion per side should be within the range of 20 g / m 2 By setting the coating weight at 300 g / m or more, the flat corrosion resistance, acidic environment corrosion resistance, and sacrificial corrosion resistance of the plated steel material can be further improved. 2 By satisfying the following conditions, the workability of the plated steel material can be further improved.

[0056] Next, a method for producing the plated steel material according to the present embodiment will be described, but the method for producing the plated steel material according to the present embodiment is not particularly limited. For example, the plated steel material according to the present embodiment can be obtained according to the production conditions described below.

[0057] In the method for producing a plated steel material according to the present embodiment, a steel material is annealed in a reducing atmosphere, and the temperature of the annealed steel material is reduced to (coating bath temperature -20)°C or lower, and then the steel material is immersed in a hot-dip coating bath and is removed from the hot-dip coating bath to form a coating layer on the surface of the steel material. Next, a galvanic flux of 5000 (L / min / m) is applied to the steel material in the range from the bath temperature until the temperature of the coating layer reaches 320°C. 2 ) or less, while blowing cooling gas at an average cooling rate of 15 ° C / sec or more, and then, in the range of 320 to 260 ° C, a flux of 25,000 (L / min / m 2 ) or higher, while spraying cooling gas at an average cooling rate of 5°C / sec or less.

[0058] Annealing of the steel material to be plated is carried out in a reducing atmosphere. The reducing atmosphere and annealing conditions are not particularly limited. By this annealing, oxides present on the surface of the steel material are removed as much as possible.

[0059] Next, the steel immediately after annealing is cooled by a cooling gas such as nitrogen until the temperature of the steel is equal to or lower than (coating bath temperature -20)°C, and then immersed in a hot-dip coating bath. By lowering the temperature of the steel by 20°C or more below the coating bath temperature, the surface roughness of the Fe-Al-based interfacial alloy layer (surface roughness on the Zn-Al-Mg alloy layer side) formed at the interface between the steel and the coating layer is reduced.

[0060] The chemical composition of the plating bath may be appropriately adjusted so as to obtain the above-mentioned chemical composition of the plating layer. The temperature of the plating bath is not particularly limited, and any temperature at which hot-dip plating can be performed may be appropriately selected. For example, the plating bath temperature may be set to a value about 20°C or higher than the melting point of the plating bath.

[0061] Next, the steel material is pulled up from the hot-dip galvanizing bath. The coating weight of the coating layer can be controlled by controlling the pulling speed of the steel material. If necessary, the coating weight of the coating layer may be controlled by wiping the steel material to which the coating layer is attached. The coating weight of the coating layer is not particularly limited and can be within the above-mentioned range, for example.

[0062] Next, the plating layer is cooled. The plating layer is first cooled from the bath temperature to 320°C at an average cooling rate of 15°C / sec or more. The average cooling rate at which the plating layer is cooled from the bath temperature to 320°C may be 30°C / sec or less. The cooling is performed, for example, by spraying a cooling gas, and the flux of the cooling gas is set to 5000 (L / min / m 2 ) or less to minimize vibration of steel materials. 2 When cooling is performed by spraying cooling gas, a plurality of nozzles for spraying the cooling gas may be arranged along the transport path of the steel material, and the cooling gas may be sprayed from the nozzles.

[0063] In the range from the bath temperature to 320°C, the α phase and MgZn2 phase are crystallized, and furthermore, the eutectic reaction between the α phase and MgZn2 phase progresses, promoting the formation of a binary eutectic structure of the α phase and MgZn2 phase (α phase / MgZn2 eutectic structure). At this time, by cooling at a rate of 15°C / sec or more in the range from the bath temperature to 320°C while suppressing the flux of cooling gas to suppress vibration of the steel material, the crystallization of the ternary eutectic structure originating from the surface of the coating layer is less likely to proceed.

[0064] Next, the temperature range was 320 to 260°C, and the flux was 25,000 (L / min / m 2 ) or more, while cooling is performed at an average cooling rate of 5°C / sec or less. In this case, multiple nozzles for blowing the cooling gas are arranged along the steel material transport path. The flow rate is set to 25,000 (L / min / m 2 ) or more, the plating layer is vibrated by blowing the cooling gas. The flux of the cooling gas in the range of 320 to 260°C is 80,000 (L / min / m 2 ) or less. This starts the crystallization of the ternary eutectic structure, which has been suppressed up to now, and at this time, the (002) plane of the η-Zn phase contained in the ternary eutectic structure is oriented so as to be parallel to the surface of the plating layer.

[0065] In cooling within the range from the bath temperature to 320°C and within the range from 320°C to 260°C, the cooling gas to be sprayed is not particularly limited, and may be a non-oxidizing gas such as nitrogen, an inert gas such as argon, or air, or a mixed gas of these.

[0066] When controlling the flux of cooling gas, the shape of the gas nozzle from which the cooling gas is ejected is, for example, in the range of 1 to 50 mm in diameter. The angle between the tip of the gas nozzle and the steel plate is, for example, in the range of 70 to 110°, and more preferably 90° (right angle). The distance between the tip of the gas nozzle and the steel plate is in the range of 30 to 1000 mm. Note that the shape, angle, and distance of the gas nozzle are merely examples and are not limited to the above ranges.

[0067] The cooling conditions below 260° C. are not particularly limited, and either air cooling or natural cooling may be used.

[0068] By cooling the plating layer so as to satisfy the above-mentioned conditions, a plating layer that satisfies the above formula (1) is formed. The reason for this is presumed to be as follows.

[0069] In the above manufacturing method, the surface roughness of the Fe-Al-based interface alloy layer is reduced by lowering the temperature of the steel material by 20°C or more than the temperature of the plating bath when the steel material is immersed in the plating bath, and the nucleation sites of the ternary eutectic structure are reduced. The temperature difference between the temperature of the steel material and the plating bath temperature when the steel material is immersed in the plating bath is 40°C or less. If the temperature difference between the temperature of the steel material and the plating bath temperature when the steel material is immersed in the plating bath exceeds 40°C, the plating appearance is poor. Then, when the steel material immersed in the plating bath is pulled up, the steel material is quenched in the range from the bath temperature to 320°C while suppressing vibration of the steel material, thereby crystallizing the α-phase and MgZn2 phase in the plating layer, while suppressing the crystallization of the ternary eutectic structure, and the starting temperature of the eutectic reaction is set to a temperature lower than the eutectic starting temperature predicted from the plating composition. Next, the material is cooled under the above-mentioned conditions in the range of 320°C to 260°C to initiate crystallization of the ternary eutectic structure. However, since the crystallization occurs at a temperature lower than the eutectic start temperature predicted from the coating composition, it is believed that the (002) plane of the η-Zn phase contained in the ternary eutectic structure becomes oriented parallel to the surface of the coating layer, thereby satisfying the above formula (1). EXAMPLES

[0070] Examples of the present invention will be described below. However, the conditions in the examples are merely examples of conditions adopted to confirm the feasibility and effects of the present invention. The present invention is not limited to these examples of conditions. Various conditions may be adopted in the present invention as long as they do not deviate from the gist of the present invention and achieve the object of the present invention.

[0071] A hot-rolled steel sheet with a thickness of 1.6 mm was used as the base sheet for plating. This base sheet for plating was annealed. The annealing conditions were an N2-4% H2 atmosphere, a soaking temperature of 800°C, and a soaking time of 2 minutes. Next, the annealed base sheet for plating was air-cooled with N2 gas to adjust the temperature at the time of immersion in the plating bath to (plating bath temperature - 20)°C or less, and then immersed in various hot-dip plating baths and pulled up at a pulling speed of 20 to 200 mm / sec. During pulling, the coating weight was controlled by N2 wiping gas. After the steel material was pulled out of the plating bath, it was cooled under the conditions shown in Table 2.

[0072] When cooling to bath temperatures of up to 320°C and in the range of 320 to 260°C, N2 gas was used as the cooling gas, and the gas flux was controlled as shown in the table. The shape of the gas nozzle from which the cooling gas was ejected was 6 mm in diameter, the angle between the tip of the gas nozzle and the steel plate was a right angle, and the distance between the tip of the gas nozzle and the steel plate was 35 mm. In this manner, plated steel products No. 1 to No. 50 were produced.

[0073] The chemical composition of the plating layer was as shown in Table 1. The metal structure of the plating layer was evaluated, and the results are shown in Table 3. Furthermore, the acidic environment corrosion resistance and sacrificial corrosion protection of the plated steel material were evaluated, and the results are shown in Table 3.

[0074] The chemical composition of the plating layer was measured by immersing a sample cut to a size of 30 mm x 30 mm in a 10% HCl aqueous solution containing an inhibitor to pickle and peel off the plating layer, and then performing ICP analysis of the elements dissolved in the aqueous solution.

[0075] The area ratio of the [α-phase / MgZn2 eutectic structure] was evaluated as follows. First, the surface of the plating layer was polished to a mirror state by mechanical polishing and colloidal polishing. Next, the plating layer surface was observed at a magnification of 5000 times (area of ​​200 μm vertical and 200 μm horizontal) using a field emission scanning electron microscope (FE-SEM) equipped with an energy dispersive elemental analyzer (EDS), and an element distribution image was taken using EDS. In the element distribution image, the phase in which Mg and Zn coexist was identified as the MgZn2 phase, and the phase containing Al and Zn was identified as the α phase, and the [α-phase / MgZn2 eutectic structure] in which these were in a lamellar form was identified. Then, the area ratio of the [α-phase / MgZn2 eutectic structure] contained in the field of view was calculated by binarization using image analysis software.

[0076] I(002) in formula (1) Zn / {I(100) Zn +I(101) ZnThe measurement method of} was as follows. First, the surface of the plating layer was made into a mirror state in the same manner as above. Next, an X-ray diffraction measurement was performed using an X-ray diffractometer (Rigaku Co., Ltd., model number RINT-TTR III) with an X-ray output of 50 kV, 300 mA, a copper target, a goniometer TTR (horizontal goniometer), a Kβ filter slit width of 0.05 mm, a longitudinal limiting slit width of 2 mm, a receiving slit width of 8 mm, and a receiving slit 2 open, and with a scan speed of 5 deg. / min, a step width of 0.01 deg, and a scan axis 2θ (5 to 90°) as the measurement conditions. Then, the diffraction intensity of the (100) plane of the η-Zn phase (maximum intensity in the range of 38.993 ± 0.2°), the diffraction intensity of the (002) plane (maximum intensity in the range of 36.297 ± 0.2°), and the diffraction intensity of the (101) plane (maximum intensity in the range of 43.232 ± 0.2°) were measured, respectively. The diffraction intensity was the intensity excluding the background intensity. From the obtained diffraction intensity, I(002) Zn / {I(100) Zn +I(101) Zn} was requested.

[0077] Whether or not the plating layer contained an Mg2Sn phase was judged by whether or not a diffraction peak specific to Mg2Sn appeared when the above-mentioned X-ray diffraction measurement was performed.

[0078] The corrosion resistance in an acidic environment was evaluated as follows. The plated steel material was cut into a size of 150 mm x 50 mm to prepare a test piece. The end faces of the test piece were protected with polyester tape manufactured by Nitto Denko so that they would not be exposed, and then the area of ​​the flat part to be evaluated for corrosion was measured.

[0079] The test specimens, whose ends were protected with tape, were then subjected to the artificial acid rain cycle test specified in JISH8502:1999. The artificial acid rain cycle test consisted of one cycle of spraying the acid test liquid (spraying time: 2h, temperature: 35℃, pH: 3.5), drying (drying time: 4h, temperature: 60℃, humidity: 20-30%RH), and wetting (wetting time: 2h, temperature: 50℃, humidity: 95%RH), and this cycle was repeated. The acid test liquid used was 5% NaCl to which HNO3·H2SO4 was added, and the pH was adjusted to 3.5 by adding NaOH.

[0080] After the artificial acid rain cycle test, the tape protecting the end faces of the test pieces was peeled off and the pieces were immersed in a 30% chromic acid (VI) solution at 25°C for 10 minutes to remove the corrosion products that had formed on the sample surface. The weight of the test pieces after immersion in the chromic acid (VI) solution was measured, and the difference from the weight before the test was calculated. This was then divided by the area of ​​the surface to be evaluated to convert it into corrosion weight loss and evaluate corrosion resistance. The evaluation criteria were as follows: "AAAA", "AAA", "AA" and "A" were deemed to be pass marks. "AAAA", "AAA", "AA" and "A" were deemed to be pass marks.

[0081] AAAA: Corrosion loss of 20g / m after 60 cycles 2 below AAA: Corrosion weight loss of 20g / m after 60 cycles 2 Super 40g / m 2 below AA: Corrosion loss of 40g / m after 60 cycles 2 Super 60g / m 2 below A: Corrosion weight loss of 60g / m after 60 cycles 2 Super 100g / m 2 below B: Corrosion loss of 100g / m after 60 cycles 2 super

[0082] Sacrificial corrosion protection (simulated edge corrosion resistance) was evaluated as follows. Plated steel was cut to 100mm x 100mm to prepare test pieces. The plating layer in a 25mm diameter area centred on the intersection of the diagonals of the test piece was removed by milling to expose the steel sheet (base steel). A neutral salt spray test as specified in JIS Z2371:2015 was carried out on the exposed 25mm diameter area of ​​the base steel, and evaluation was based on the occurrence of red rust in the exposed area of ​​the base steel. The evaluation criteria for sacrificial corrosion protection are as follows. "AAA", "AA" and "A" were considered to be passing.

[0083] AAA: Red rust area rate 5% or less after 2200 hours AA: Red rust area ratio over 5% and 10% or less after 1800 hours A: Red rust area ratio over 10% and 15% or less after 1000 hours B: Red rust area ratio exceeds 15% after 1000 hours

[0084] Nos. 1 to 32, 42 to 45, 47, 48 and 50 (Examples) according to the present invention had appropriately controlled chemical compositions and metal structures of the plating layers, and were excellent in both acidic environment corrosion resistance and sacrificial corrosion resistance.

[0085] Comparative Example No. 33 had an insufficient amount of Al in the plating layer, which resulted in insufficient corrosion resistance in an acidic environment.

[0086] Comparative Example No. 34 had an excessive amount of Al in the coating layer, which resulted in excessive formation of α-phase dendrites, which functioned as nucleation sites for the η-Zn phase, making it impossible to ensure the orientation of the η-Zn phase, resulting in insufficient acidic environment corrosion resistance and sacrificial corrosion protection.

[0087] Comparative Example No. 35 had an insufficient amount of Mg in the coating layer, which meant that the orientation of the η-Zn phase could not be ensured, and both the acidic environment corrosion resistance and the sacrificial corrosion resistance were insufficient.

[0088] In the comparative example, No. 36, the amount of Mg in the coating layer was excessive, which resulted in an excess of MgZn2 phase, making it impossible to ensure the orientation of the η-Zn phase, and resulting in insufficient corrosion resistance in an acidic environment.

[0089] In the comparative example, No. 37, the flux of cooling gas was excessive in the cooling bath temperature range of 320° C. As a result, in No. 37, the orientation of the η-Zn phase could not be ensured, and the corrosion resistance in an acidic environment was insufficient.

[0090] In comparative example No. 38, the flux of cooling gas was insufficient during cooling in the range of 320° C. to 260° C. Therefore, in No. 38, the orientation of the η-Zn phase could not be ensured, and the corrosion resistance in an acidic environment was insufficient.

[0091] In the comparative example, No. 39, the cooling rate was slow in the cooling bath temperature range of 320° C. As a result, the orientation of the η-Zn phase could not be ensured in No. 39, and the corrosion resistance in an acidic environment was insufficient.

[0092] In the comparative example, No. 40, the cooling rate was excessive in the range of 320° C. to 260° C. Therefore, in No. 40, the orientation of the η-Zn phase could not be ensured, and the corrosion resistance in an acidic environment was insufficient.

[0093] In Comparative Example No. 41, the temperature of the steel sheet when immersed in the coating bath was more than (bath temperature - 20)° C. Therefore, in No. 41, the orientation of the η-Zn phase could not be ensured, and the corrosion resistance in an acidic environment was insufficient.

[0094] In comparative example No. 46, the cooling rate was excessive in the range of 320° C. to 260° C. Therefore, in No. 46, the orientation of the η-Zn phase could not be ensured, and the corrosion resistance in an acidic environment was insufficient.

[0095] In the comparative example, No. 49, the difference between the sheet entry temperature and the bath temperature was over 40° C., which resulted in poor plating appearance.

[0096] [Table 1]

[0097] [Table 2]

[0098] [Table 3] [Industrial Applicability]

[0099] INDUSTRIAL APPLICABILITY The plated steel material according to the present disclosure has excellent sacrificial corrosion resistance and corrosion resistance in acidic environments and is therefore highly industrially applicable. [Explanation of symbols]

[0100] 1...plated steel material, 11...steel material, 12...plating layer

Claims

1. Steel and A plating layer on the steel material; The chemical composition of the plating layer is, in mass%, Al: 6.0-30.0%, Mg: 3.0 to 15.0%, Fe: 0.01-15.00%, Si: 0-2.0%, Ca: 0 to 2.00%; Sb: 0-0.50%, Pb: 0-0.50%, Cu: 0-1.00%, Sn: 0-1.00%, Ti: 0-1.00%, Cr: 0-1.00%, Nb: 0-1.00%, Z r: 0-1.00%, Ni: 0-1.000%, Mn: 0-1.00%, Mo: 0-1.00%, Ag: 0-1.00%, Li: 0-1.00%, La: 0-1.000%, C The steel sheet contains one or more elements selected from the group consisting of e: 0-1.000%, B: 0-0.500%, Y: 0-0.50%, P: 0-0.50%, Sr: 0-0.50%, Co: 0-0.500%, Bi: 0-0.500%, In: 0-0.50%, V: 0-0.500%, and W: 0-0.50%, and the total amount of these elements is 0-5.0%; The balance is composed of Zn and impurities. A plated steel material, wherein a diffraction intensity obtained from an X-ray diffraction measurement of the plating layer satisfies the following formula (1): 0.5≦I(002) Ｚｎ / {I(100) Ｚｎ +I(101) Ｚｎ }≦25.0 …(1) However, I(002) in formula (1) Ｚｎ is the diffraction intensity of (002) of the η-Zn phase, and I(100) Ｚｎ is the diffraction intensity of (100) of the η-Zn phase, and I(101) Ｚｎ is the diffraction intensity of (101) of the η-Zn phase.

2. 2. The plated steel material according to claim 1, wherein the Al and Mg content of the plating layer is Al: 10.0 to 25.0% and Mg: 4.5 to 15.0%, respectively.

3. 2. The plated steel material according to claim 1, wherein the Al and Mg content of the plating layer is Al: 15.0 to 22.0% and Mg: 5.5 to 15.0%, respectively.

4. The plated steel material according to claim 1 , wherein a diffraction intensity obtained from an X-ray diffraction measurement of the plating layer satisfies the following formula (2): 1.5≦I(002) Ｚｎ / {I(100) Ｚｎ +I(101) Ｚｎ }≦25.0 …(2)

5. The surface structure of the plating layer when viewed from above contains [α / MgZn ２ The plated steel material according to any one of claims 1 to 3, wherein an area ratio of the eutectic structure is 5 to 70%.

6. The plated steel material according to claim 4, wherein the surface structure of the plated layer when viewed in a plane has an area ratio of 5 to 70% of the α / MgZn 2 eutectic structure.

7. The surface structure of the plating layer when viewed from above contains [α / MgZn ２ The plated steel material according to any one of claims 1 to 3, wherein an area ratio of the eutectic structure is 10 to 70%.

8. The plated steel material according to claim 4, wherein the surface structure of the plated layer when viewed in plan has an area ratio of 10 to 70% of the α / MgZn 2 eutectic structure.

9. The Sn content of the plating layer is, in mass%, Sn: 0.05 to 0.50%, The X-ray diffraction measurement of the plating layer showed that Mg ２ The plated steel material according to claim 1 , wherein a Sn phase is detected.

10. The plated steel material according to any one of claims 1 to 3, containing one or both of La and Ce in a total amount of 0.005 to 0.500%.

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