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 formula.

Description

[Technical field]

[0001] The present invention relates to a plated steel material. This application claims priority based on Japanese Patent Application No. 2023-064063 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] In recent years, plated steel materials for building materials used in roofs, walls, and the like are required to have excellent red rust resistance, which suppresses the occurrence of red rust on the base steel when the base steel is exposed, and excellent base steel corrosion resistance, which suppresses an increase in the corrosion depth of the base steel. However, in the prior art, there has been little research into improving both red rust resistance and base steel corrosion resistance.

[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 to the first region is 3.5 or more is defined as the first region, and the area where the intensity ratio is less than 3.5 is defined as the second region, it is said that by making the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion 30% or more, it is possible to intentionally make letters, designs, etc. appear on the surface of the plating layer, but red rust resistance and corrosion resistance of the base steel have 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 areas, but red rust resistance and corrosion protection of the base steel are 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 red rust resistance and base steel corrosion resistance. [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% Contains one or both of La and Ce in total at 0.005 to 0.500%. 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: 0~1.00%, Li: 0~1.00%, B It contains one or more elements selected from the group consisting of: Y: 0-0.500%, 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 the diffraction intensity obtained from an X-ray diffraction measurement of the plating layer satisfies the following formula (1): 0.15≦I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn}≦3.00 …(1) However, I(100) in formula (1) Zn is the diffraction intensity of (100) of the η-Zn phase, and I(002) Zn is the diffraction intensity of (002) of the η-Zn phase, and I(101) Zn is the diffraction intensity of (101) of the η-Zn phase, and I(100) Zn is the diffraction intensity of (100) 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 total content of one or both of La and Ce in the plating layer is 0.010 to 0.500%, The plated steel material according to [1] or [2], wherein the number of at least one of a LaCe-containing intermetallic compound phase, a La-containing intermetallic compound phase, and a Ce-containing intermetallic compound phase is at least one within a 200 μm × 200 μm field of view of the surface structure when the plating layer is viewed in a plane. [4] The total content of one or both of La and Ce in the plating layer is 0.050 to 0.500%, The plated steel material according to any one of [1] to [3], wherein the number of at least one of a LaCe-containing intermetallic compound phase, a La-containing intermetallic compound phase, and a Ce-containing intermetallic compound phase is 3 or more within a 200 μm × 200 μm field of view of a surface structure when the plating layer is viewed in a plane. [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] A plated steel material according to any one of claims 5 to 7, wherein the diffraction intensity obtained from X-ray diffraction measurement of the plating layer satisfies the following formula (2): 0.25≦I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn}≦3.00 …(2) [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. Effect of the Invention

[0011] According to the present invention, it is possible to provide a plated steel material having excellent red rust resistance and base steel corrosion prevention properties. [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] The sacrificial corrosion protection properties of a plating layer are achieved by forming a plating layer containing elements (e.g., Zn, Mg) that have a higher ionization tendency than the base steel on the surface of a steel material, and allowing the plating layer to corrode preferentially over the base steel.

[0014] Therefore, the present inventors have conducted extensive research to improve the sacrificial corrosion protection 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 corrosion products generated by the corrosion of Zn, so the sacrificial corrosion protection of the base steel is considered to be high. Therefore, it was thought that if the (100) plane of the η-Zn phase was oriented parallel to the surface of the plating layer, the sacrificial corrosion protection properties of the Zn plating layer containing Al and Mg, specifically the red rust resistance and corrosion protection of the base steel, could be improved.

[0015] Therefore, the present inventors attempted to orient the (100) plane of the η-Zn phase contained in the coating layer parallel to the surface of the coating layer. When the 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, MgZn2 phase, and η-Zn phase is formed. At this time, it was found that if a large amount of dendritic α phase crystallizes, the ternary eutectic structure containing the η-Zn phase is oriented in a random direction. Therefore, the inventors roughened the surface of the steel material and added one or both of La and Ce to the coating layer, and further controlled the cooling conditions. As a result, it was found that the crystallization of the α phase was suppressed and the crystallization of the ternary eutectic structure proceeded from the vicinity of the interface between the coating layer and the base steel, and as a result, the (100) plane of the η-Zn phase contained in the ternary eutectic structure was 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 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%, La or Ce is contained in a total of 0.005-0.500%, 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: 0-1.00%. The plated steel material contains one or more elements selected from the group consisting of 0.0%, Mn: 0-1.00%, Mo: 0-1.00%, Ag: 0-1.00%, Li: 0-1.00%, 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] 0.15≦I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn}≦3.00 …(1)

[0018] However, I(100) in formula (1) Zn is the diffraction intensity of the (100) plane of the η-Zn phase, and I(002) Zn is the diffraction intensity of the (002) plane of the η-Zn phase, and I(101) Zn is the diffraction intensity of the (101) plane of the η-Zn phase, and I(100) Zn is the diffraction intensity of the (100) plane 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.). "Red rust resistance" refers to the property of suppressing the occurrence of red rust on steel at bare steel parts (e.g., cut end surfaces of plated steel, cracked parts of the plated layer during processing, and parts where the steel is exposed due to peeling of the plated layer). "Base steel corrosion resistance" refers to the property of suppressing the increase in corrosion depth when the steel corrodes at bare steel parts. "Plane corrosion resistance" refers to the property of the plated layer (specifically, the Zn-Al-Mg alloy layer) itself being resistant to corrosion. "Plating layer" refers to a plated film produced by so-called hot-dip galvanizing 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, sacrificial corrosion resistance, and workability. 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 there is an excess of Al, the Mg concentration and Zn concentration are relatively reduced, and the red rust resistance and base steel corrosion resistance deteriorate. 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, or 20.0% or less.

[0026] <Mg:3.0~15.0%> Mg is an essential element for ensuring flat surface corrosion resistance, red rust resistance, and base steel corrosion resistance. Therefore, the Mg concentration is set to 3.0% or more. The Mg concentration may be set to 4.5% or more, or 6.0% or more. On the other hand, if the Mg concentration is excessive, the workability, particularly the powdering resistance, 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% to 2.0%> The Si concentration may be 0%. On the other hand, Si contributes to the improvement of the corrosion resistance of the planar part. 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 planar corrosion resistance, rust resistance, and subway corrosion protection performance deteriorate. 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% to 2.00%> The Ca concentration may be 0%. On the other hand, Ca is an element that can adjust the optimal Mg elution amount for imparting corrosion resistance to the planar part. 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 corrosion resistance and workability of the planar part 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] <Total of one or both of La and Ce: 0.005 to 0.500%> When either one or both of La and Ce are contained in the plating layer, it contributes to the improvement of rust resistance and subway corrosion protection performance. If the total of La and Ce is less than 0.005%, the rust resistance and subway corrosion protection performance cannot be improved. Also, if the total of La and Ce exceeds 0.500%, the corrosion resistance of the planar part deteriorates. Therefore, the total of one or both of La and Ce is set to 0.005 to 0.500%. The total of La and Ce may be 0.008% or more, 0.010% or more, or 0.050% or more. Also, the total of La and Ce may be 0.200% or less, 0.100% or less. When La and Ce are contained, the crystallization of the α phase is suppressed when the plating layer solidifies, and thus, the (100) plane of the η-Zn phase, which is abundantly contained in the ternary eutectic structure, is likely to be oriented parallel to the surface of the plating layer. Therefore, it is considered that the rust resistance and subway corrosion protection performance are improved.

[0031] Furthermore, the plating layer according to this embodiment contains the following components: 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 The alloy may contain one or more elements selected from the group consisting of Li: 0-1.00%, Li: 0-1.00%, 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%. 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, the total amount may be 0%.

[0032] <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 red rust resistance and base steel corrosion resistance. Therefore, the respective 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 respective concentrations of Sb and Pb are set to 0.50% or less. The respective concentrations of Sb and Pb may be set to 0.40% or less, 0.30% or less, or 0.25% or less.

[0033] <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 red rust resistance and base steel 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.

[0034] <Ni:0~1.000%> The Ni concentration may be 0%. On the other hand, these contribute to improving red rust resistance and base steel 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 set to 1.000% or less. The Ni concentration may be 0.800% or less, 0.700% or less, or 0.600% or less.

[0035] <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 red rust resistance and base steel 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.

[0036] <B:0~0.500%> The concentration of B may be 0%. On the other hand, B contributes to improving red rust resistance and base steel corrosion resistance. Therefore, each 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, each 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 red rust resistance and base steel 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 B, 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, 0.30% or less.

[0038] <Co、Bi、V:それぞれ0~0.500%> The concentrations of Co, Bi, and V may each be 0%. On the other hand, Co, Bi, and V contribute to improving red rust resistance and base steel corrosion resistance. Therefore, the concentrations of Co, Bi, and V may each 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 each set to 0.500% or less. The concentrations of Co, Bi, and V may each be set to 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%. Meanwhile, In and W contribute to improving red rust resistance and base steel corrosion resistance. Therefore, the respective concentrations of In and W may be 0.10% or more, 0.15% or more, or 0.20% or more. Meanwhile, if the concentrations of In and W are excessive, the corrosion resistance of the flat 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 portion corrosion resistance, red rust resistance, and base steel corrosion resistance. 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 according to this embodiment. For example, trace amounts of components other than Fe may be mixed in as impurities into the plating layer due to mutual atomic diffusion between the base steel 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 may be in the range of 70% or less, in the range of 5 to 70%, or in the range of 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 amount 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 red rust resistance 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] Furthermore, the plating layer may contain one or more of a LaCe-containing intermetallic compound phase, a La-containing intermetallic compound phase, and a Ce-containing intermetallic compound phase, as described below.

[0048] The plating layer may contain other phases as the balance, such as an Al-Ca-Si phase.

[0049] 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 (100) plane of the η-Zn phase is oriented parallel to the surface of the plating layer, improving both the red rust resistance and the corrosion protection of the base steel. It is more preferable that the following formula (2) is satisfied. I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn If the ratio of I(100) to I(100) is less than 0.15, the orientation of the (100) plane of the η-Zn phase is insufficient, and the red rust resistance and the corrosion resistance of the base steel are insufficient. Zn / {I(002) Zn +I(101) Zn +I(100) Zn If the value of} exceeds 3.00, the corrosion resistance of the flat portion may decrease.

[0050] 0.15≦I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn}≦3.00 …(1)

[0051] 0.25≦I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn}≦3.00 …(2)

[0052] However, I(100) in formula (1) and formula (2) Zn is the diffraction intensity of the (100) plane of the η-Zn phase, and I(002) Zn is the diffraction intensity of the (002) plane of the η-Zn phase, and I(101) Zn is the diffraction intensity of the (101) plane of the η-Zn phase, and I(100) Zn is the diffraction intensity of the (100) plane of the η-Zn phase.

[0053] In addition, when the plating layer contains one or both of La and Ce in a total of 0.01 to 0.50%, it is preferable that the plating layer contains at least one of LaCe-containing intermetallic compound phase, La-containing intermetallic compound phase, and Ce-containing intermetallic compound phase in a total of one or more in a 200 μm×200 μm visual field of the surface structure when viewed from above. More preferably, it is preferable that at least one of these intermetallic compound phases contains three or more in a 200 μm×200 μm visual field. It is preferable that at least one of the intermetallic compound phases contains 10 or less in a 200 μm×200 μm visual field.

[0054] The LaCe-containing intermetallic compound phase is an intermetallic compound phase containing La and Ce, the La-containing intermetallic compound phase is an intermetallic compound phase containing La, and the Ce-containing intermetallic compound phase is an intermetallic compound phase containing Ce. Elements other than La and Ce contained in these intermetallic compound phases include Al, Ca, Si, Mg, and Zn. For example, these intermetallic compound phases may contain Al-Ca-Si-Mg-Zn-(La,Ce) phase, Ca-Zn-(La,Ce) phase, etc. Note that the notation (La,Ce) means either or both of La and Ce. When such an intermetallic compound phase is contained, the (100) plane of the η-Zn phase is strongly oriented parallel to the surface of the plating layer, and the red rust resistance and the corrosion resistance of the base steel are further improved.

[0055] 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.

[0056] I(100) in formula (1) and formula (2) Zn / {I(002) Zn +I(101) Zn +I(100) 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(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn} is required.

[0057] 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.

[0058] Furthermore, the method for measuring the number of LaCe-containing intermetallic compound phases, La-containing intermetallic compound phases, and Ce-containing intermetallic compound phases in the surface structure of the plating layer 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 in a mirror state. Next, a rectangular observation field of 200 μm in length and 200 μm in width is set on the surface of the plating layer. An element distribution image is taken of this observation field using SEM-EDS. In this element distribution image, a phase containing either or both of La and Ce is identified as one of the LaCe-containing intermetallic compound phases, La-containing intermetallic compound phase, and Ce-containing intermetallic compound phase. Then, the number of these intermetallic compounds is counted.

[0059] 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, red rust resistance, and base steel 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.

[0060] 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.

[0061] In the method for producing a plated steel material of this embodiment, a steel material with irregularities formed on its surface is used as an original sheet for plating. This steel material is annealed in a reducing atmosphere, and the steel material immediately after annealing is immersed in a hot-dip plating bath and then pulled out to form a plating layer on the surface of the steel material. Next, the plating layer is cooled from the bath temperature to 340°C at an average cooling rate of 15°C / sec or more, and then cooled in the range of 340 to 320°C at a flux of 15,000 (L / min / m 2 ) or higher, while spraying cooling gas at an average cooling rate of 7°C / sec or less.

[0062] The roughness of the surface of the steel material to be plated is expressed as the curve length L of the roughness curve per reference length L0. p Ratio (L p / L0) is 1.08 or more. p By setting the ratio of L0 to 1.08 or more, nucleation sites for crystallizing a ternary eutectic structure are formed near the interface between the coating layer and the steel sheet. (L p The upper limit of the curvature length L0 is preferably 3.00 or less, and may be 2.50 or less. The reference length L0 is the length of the coating layer in the longitudinal direction when the coating layer is viewed in cross section, and the curve length L p is the curve length of the roughness curve relative to the reference length L0 when the plating layer is viewed in cross section, i.e., the total length of the contour line of the surface of the plating layer.

[0063] The adjustment of the roughness of the steel surface is not particularly limited, and may be performed, for example, by rolling the plated original sheet with a rolling roll or a roll for temper rolling whose roll surface has been adjusted to a desired roughness, thereby transferring the surface shape of the roll. Alternatively, the adjustment may be performed by pickling.

[0064] (L p The measurement of (L0) is performed, for example, using a shape measuring laser microscope (model number: VK-8700) manufactured by Keyence Corporation. The measurement conditions are, for example, scan area: 200 μm×200 μm, measurement mode: laser confocal, measurement quality: high precision, pitch: 0.75 μm, double scan: ON, optical zoom: 1x, objective lens name: Plan, γ coefficient: 0.45, offset: 0%. p The measuring device used for measuring L0) is not limited to the above example.

[0065] 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.

[0066] Next, the steel material immediately after annealing is immersed in a hot-dip galvanizing bath. The chemical composition of the hot-dip galvanizing bath may be appropriately adjusted so as to obtain the above-mentioned chemical composition of the coating layer. The temperature of the hot-dip galvanizing bath is not particularly limited, and a temperature at which hot-dip galvanizing can be performed may be appropriately selected. For example, the temperature of the galvanizing bath may be set to a value about 20° C. or more higher than the melting point of the galvanizing bath.

[0067] 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.

[0068] Next, the plating layer is cooled. The cooling is performed at an average cooling rate of 15°C / sec or more until the temperature of the plating layer is reduced from the bath temperature to 340°C. The average cooling rate until the temperature of the plating layer is reduced from the bath temperature to 340°C may be 30°C / sec or less. The cooling can be performed, for example, by spraying a cooling gas. When cooling by spraying a cooling gas, a plurality of spray nozzles for the cooling gas may be arranged along the conveying path of the steel material, and the cooling gas may be sprayed from the nozzles. By cooling at a rate of 15°C / sec or more in the range from the bath temperature to 340°C, the generation of a dendritic α-phase that is generated in the early stage of the solidification stage is suppressed. The α-phase dendrites may become nucleation sites during the crystallization of a ternary eutectic structure, and by suppressing the generation of the α-phase, a ternary eutectic structure is formed from nucleation sites near the interface between the steel material and the plating layer.

[0069] Next, the temperature range was 340 to 320 °C, and the flux was 15,000 (L / min / m 2 ) or more, while blowing cooling gas at an average cooling rate of 7°C / sec or less. In this case, cooling may be performed at an average cooling rate of 2°C or more. In addition, the flux of the cooling gas during cooling is 25,000 (L / min / m 2 In this case, multiple cooling gas spray nozzles are arranged along the steel material transport path. The flow rate is set to 15,000 (L / min / m 2 ) or more, the coating layer is vibrated by blowing cooling gas without being excessively supercooled. As a result, crystallization of the ternary eutectic structure starts near the interface between the coating layer and the steel material, and the ternary eutectic structure grows toward the surface of the coating layer.

[0070] 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 mixture of these gases.

[0071] 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.

[0072] The cooling conditions below 320° C. are not particularly limited, and either air cooling or natural cooling may be used.

[0073] 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.

[0074] In the above manufacturing method, by providing unevenness on the surface of the steel material before hot-dip coating, a nucleation site of the ternary eutectic structure is formed near the interface between the steel material and the coating layer. Then, by cooling the steel material immersed in the coating bath under the above conditions when it is pulled up, the nucleation site from which the crystallization of the ternary eutectic structure starts is directed to be near the interface between the steel material and the coating layer, not the α-phase dendrite. The ternary eutectic structure crystallized from the interface between the steel material and the coating layer has a crystal orientation oriented in a certain direction, unlike the case where the crystallization starts from the α-phase dendrite. As a result, it is considered that the (100) plane of the η-Zn phase contained in the ternary eutectic structure is oriented parallel to the surface of the coating layer, and the above formula (1) is satisfied. EXAMPLES

[0075] 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.

[0076] The plate used was a hot-rolled steel sheet with a thickness of 1.6 mm. The surface roughness of the hot-rolled steel sheet was controlled in advance using a skin pass mill or the like. The surface roughness was calculated by the curve length L of the roughness curve per the reference length L0. p Ratio (L p / L0) was adjusted to be 1.05 to 1.57.

[0077] In addition, (L p The measurement of the surface roughness (L0) was performed using a shape measuring laser microscope (model number: VK-8700) manufactured by Keyence Corporation. The measurement conditions were as follows: measurement mode: laser confocal, measurement quality: high precision, pitch: 0.75 μm, double scan: ON, optical zoom: 1x, objective lens name: Plan, γ coefficient: 0.45, offset: 0%.

[0078] Next, the plated original sheet with the adjusted surface roughness 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 plated original sheet after annealing was air-cooled with N2 gas to adjust the temperature when immersed in the plating bath to about (plating bath temperature + 20)°C, 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.

[0079] When cooling to a temperature range of 340 to 320°C, N2 gas was used as the cooling gas, and the gas flux was controlled as shown in Table 2. 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 47 were produced.

[0080] The chemical composition of the plating layer was as shown in Table 1. The metal structure of the plating layer was also evaluated, and the results are shown in Table 3. Furthermore, the red rust resistance and base steel corrosion resistance of the plated steel were evaluated, and the results are shown in Table 4.

[0081] 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.

[0082] 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 (200 μm long, 200 μm long area) 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 are in a lamellar shape 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.

[0083] I(100) in formula (1) Zn / {I(002) Zn +I(101) Zn +I(100) 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, 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(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn} was requested.

[0084] 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.

[0085] Furthermore, the number of LaCe-containing intermetallic compound phases, La-containing intermetallic compound phases, and Ce-containing intermetallic compound phases in the surface structure of the plating layer was measured. First, the surface of the plating layer was made into a mirror state in the same manner as above. Next, a rectangular observation field of 200 μm in length and 200 μm in width was set on the surface of the plating layer. An element distribution image was taken for this observation field using SEM-EDS. In this element distribution image, a phase containing either La or Ce or both was identified as one of the LaCe-containing intermetallic compound phases, La-containing intermetallic compound phases, and Ce-containing intermetallic compound phases. Then, the number of these intermetallic compounds was counted. The results are shown in Table 3. The column "LaCe-containing intermetallic compound phase" in Table 3 shows the total number of LaCe-containing intermetallic compound phases, La-containing intermetallic compound phases, and Ce-containing intermetallic compound phases.

[0086] Red rust resistance was evaluated as follows. Plated steel was cut to 100mm x 100mm to prepare test pieces. The plating layer in a 30mm 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 combined cycle test stipulated in the JASO-M609-91 method was performed on the exposed 30mm 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 red rust resistance are as follows: "AAAA", "AAA", "AA" and "A" were considered to be passing.

[0087] AAAA: Red rust area rate of 2% or less after 120 cycles AAA: Red rust area ratio over 2% to 5% after 120 cycles AA: Red rust area ratio is over 5% and 10% or less after 120 cycles A: Red rust area ratio over 10% and up to 15% after 120 cycles B: Red rust area ratio over 15% after 120 cycles

[0088] The corrosion protection of the steel substrate was evaluated as follows. The 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 (steel substrate). A combined cycle test stipulated in JASO-M609-91 was carried out on the 25mm diameter exposed area of ​​the steel substrate, and evaluation was based on the maximum steel substrate corrosion depth in the exposed area of ​​the steel substrate. The evaluation criteria for steel substrate corrosion protection are as follows: "AAA", "AA" and "A" were considered to be passing.

[0089] AAA: 0.5mm or less after 360 cycles AA: 0.5mm or less after 240 cycles A: 0.5mm or less after 180 cycles B: Over 0.5mm at 180 cycles

[0090] In Nos. 1 to 32 and 42 to 47 (Examples) according to the present invention, the chemical composition and metal structure of the plating layer were appropriately controlled, and both the red rust resistance and the corrosion resistance of the base steel were excellent.

[0091] Comparative example No. 33 had an insufficient amount of Al in the coating layer, which resulted in insufficient corrosion protection of the base steel in No. 31.

[0092] Comparative example No. 34 had an excessive amount of Al in the coating layer, which resulted in excessive formation of α-phase dendrites in No. 32, which functioned as nucleation sites for the η-Zn phase, making it impossible to ensure the orientation of the η-Zn phase, and resulting in insufficient red rust resistance and base steel corrosion resistance.

[0093] Comparative example No. 35 had an insufficient amount of Mg in the coating layer, and therefore No. 33 was insufficient in both red rust resistance and base steel corrosion resistance.

[0094] Comparative example No. 36 had an insufficient total amount of La and Ce in the coating layer, which meant that the orientation of the η-Zn phase could not be ensured and the base steel corrosion resistance was insufficient.

[0095] In the comparative example, No. 37, the amount of Mg in the plating layer was excessive, which resulted in the red rust resistance of No. 35 being insufficient.

[0096] In comparative example No. 38, the gas flux of the cooling gas was insufficient during cooling in the range of 340 to 320° C. Therefore, in No. 38, the orientation of the η-Zn phase could not be ensured, and the red rust resistance was insufficient.

[0097] In the comparative example, No. 39, the cooling rate exceeded 7° C. / sec in the range of 340 to 320° C. Therefore, in No. 39, the orientation of the η-Zn phase could not be ensured, and the red rust resistance was insufficient.

[0098] In the comparative example, No. 40, the cooling rate was less than 15° C. / sec in the range of bath temperature to 340° C. Therefore, in No. 40, the orientation of the η-Zn phase could not be ensured, and the red rust resistance was insufficient.

[0099] In the comparative example No. 41, the surface roughness of the plated original sheet ((L p / L0) was less than 1.08. Therefore, in No. 41, the orientation of the η-Zn phase could not be ensured, and the red rust resistance was insufficient.

[0100] [Table 1]

[0101] [Table 2]

[0102] [Table 3]

[0103] [Table 4] [Industrial Applicability]

[0104] INDUSTRIAL APPLICABILITY The plated steel material according to the present disclosure has excellent red rust resistance and base steel corrosion resistance and is therefore highly industrially applicable. [Explanation of symbols]

[0105] 1...plated steel material, 11...steel material, 12...plated 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%; Contains one or both of La and Ce in a total amount of 0.005 to 0.500%, 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: 0-1.00%, 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 a diffraction intensity obtained from an X-ray diffraction measurement of the plating layer satisfies the following formula (1): 0.15≦I(100) Ｚｎ / {I(002) Ｚｎ +I(101) Ｚｎ +I(100) Ｚｎ }≦3.00 …(1) However, I(100) in formula (1) Ｚｎ is the diffraction intensity of (100) of the η-Zn phase, and I(002) Ｚｎ is the diffraction intensity of (002) of the η-Zn phase, and I(101) Ｚｎ is the diffraction intensity of (101) of the η-Zn phase, and I(100) Ｚｎ is the diffraction intensity of (100) 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. The total content of one or both of La and Ce in the plating layer is 0.010 to 0.500%, 3. The plated steel material according to claim 1, wherein the number of at least one of a LaCe-containing intermetallic compound phase, a La-containing intermetallic compound phase, and a Ce-containing intermetallic compound phase in a 200 μm × 200 μm field of view of a surface structure when the plating layer is viewed in a plane is at least one.

4. The total content of one or both of La and Ce in the plating layer is 0.050 to 0.500%, 3. The plated steel material according to claim 1, wherein the number of at least one of a LaCe-containing intermetallic compound phase, a La-containing intermetallic compound phase, and a Ce-containing intermetallic compound phase in a 200 μm × 200 μm field of view of a surface structure when the plating layer is viewed in a plane is 3 or more.

5. The surface structure of the plating layer when viewed in plan view contains [α / MgZn ２ 3. The plated steel material according to claim 1, wherein the area ratio of the eutectic structure is 5 to 70%.

6. The plated steel material according to claim 3, 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 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.

8. The plated steel material according to claim 1 or 2, wherein a diffraction intensity obtained from an X-ray diffraction measurement of the plating layer satisfies the following formula (2): 0.25≦I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn}≦3.00 …(2)

9. The plated steel material as described in claim 3, wherein the diffraction intensity obtained from the X-ray diffraction measurement of the plating layer satisfies the following formula (2). 0.25≦I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn}≦3.00 …(2)

10. The plated steel material described in claim 4, wherein the diffraction intensity obtained from the X-ray diffraction measurement of the plating layer satisfies the following formula (2). 0.25≦I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn}≦3.00 …(2)

11. The plated steel material described in claim 5, wherein the diffraction intensity obtained from the X-ray diffraction measurement of the plating layer satisfies the following formula (2). 0.25≦I(100) Zn / {I(002) Zn +I(101) Zn +I(100) Zn}≦3.00 …(2)

12. 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 or 2, in which a Sn phase is detected.

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