Technical field
[0001]The present invention relates to a plated steel sheet.
BACKGROUND
[0002]In recent years, automobile structural members, the plated steel sheet is used from the viewpoint of rust, which is mainly in the domestic market are applied galvannealed steel sheet. Galvannealed steel sheet, heat-treated alloy after performing molten zinc plating steel sheet was by diffusing Fe from the steel sheet (substrate steel sheet) in the plating layer improves the weldability and corrosion resistance after painting plating it is a steel plate. For example, plated steel sheet disclosed in Patent Document 1 is used typically as an automotive coated steel sheet in Japan.
[0003]
　Usually, the plated steel sheet for automobiles, because they are used in a state of being molded of a plate into complex shapes, often are subjected to press forming. For galvannealed steel sheet, the plating layer becomes hard by diffusion of Fe from the substrate steel sheet. Therefore, easy plating layer is peeled off, such as powdering or flaking, plating layer is also present unique problems not found in hot-dip galvanized steel sheet softer.
[0004]
　Furthermore, plated steel sheet with a plating layer of rigid, easily plated layer is damaged by external pressure, once the cracks, the crack propagates to the interface between the plated layer and the base steel (steel plate). Therefore, the plating layer is peeled off starting from the interface with the base steel (steel plate), it tends to generate a dropout is a problem.
　For example, when using the galvannealed steel sheet outer panel of an automobile, painting and plating layer is peeled off simultaneously by pebbles collision (chipping) due to stone recoil vehicle, base steel (steel plate) is likely to be exposed . Therefore, corrosion than plated steel sheet having a plating layer of soft without alloying progresses early. Thus, long-term when it is used is started attack by corrosion of the base steel, a decrease in collision safety is a concern especially if used on suspension member.
　Further, from the viewpoint of appearance, galvannealed steel sheet contains Fe in the plating layer. Therefore, when such a chipping occurs due to corrosion of the plating layer immediately rust it is likely to occur in the red-brown, also cause problems on car appearance.
[0005]
　The resolution of these problems, the plating layer has a toughness, and the application of plated steel sheet containing no Fe is effective. For example, an automotive coated steel sheet in a plating layer not containing Fe, North America, in Europe, etc. are mainly galvanized steel sheet is used. However, galvanized steel sheets have not been processed alloying hardly occurs and chipping. In addition, hardly occurs even corrosion initial red rust for the plating layer containing no Fe as galvannealed steel sheet. However, the plating layer under the paint film is easily corroded by coating lifts the painted state (swelling). Therefore, galvanized steel sheet, since the long-term use is initiated erosion base steel, it can not be said means being suitable as a plated steel sheet for automobiles.
[0006]
　The molten Zn-based plating as a method for high corrosion resistance of, include a method of incorporating the Al to Zn plating layer, a highly corrosion-resistant plated steel sheet in the building materials sector, Patent Document 2 in the indicated manner the molten Al-Zn-based plating steel sheet has been widely put into practical use. Plated layer of such a molten Al-Zn-based plated steel sheet is comprised of first crystallized out dendritic alpha-Al phase (dendrite structure), Zn phase and Al phase formed in the gap dendritic structure from a molten state It is formed from the tissue (inter dendrite structure). Dendritic structure is passivated, and, inter dendritic structure has a high Zn concentration compared with the dendritic structure. Therefore, corrosion is concentrated on the inter dendritic structure.
　As a result, the corrosion proceeds inter dendritic tissue vermicular, corrosion travel path becomes complicated. Therefore, less likely to reach the corrosion easily base steel (steel plate).
　Thus, molten Al-Zn-based plating steel sheet, when the coating is used as a bare material not made, resistant to corrosion that the thickness of the plating layer was superior to the same hot-dip galvanized steel sheet.
[0007]
　When using such a molten Al-Zn-based plated steel sheet as automotive exterior panels, after the plated steel sheet was processed and subjected to an automobile manufacturer or the like in a state that has been subjected to plating in a continuous hot-dip plating equipment, where the panel section shape , chemical conversion treatment, electrodeposition coating, intermediate coating, and that topcoating automobile comprehensive paint containing is performed in general.
[0008]
　For the purpose of improving corrosion resistance it is also considered to be contained in Mg to Zn-Al-based plating layer. For example, Patent Document 3, the plating layer during MgZn 2 Zn / Al / MgZn containing a Mg compound such as 2 to form a ternary eutectic structure, the molten Zn-Al-Mg plated steel sheet with improved corrosion resistance It has been disclosed. Sacrificial anti-corrosion plated layer by the inclusion of Mg is anticorrosion effect of increased base steel is considered to be improved.
[0009]
　Further, in Patent Document 4, by containing Sn or In, to destroy the passivation dendrite structure, the molten Al-Zn alloy coated steel sheet having improved corrosion resistance after painting is disclosed.
[0010]
　Further, Patent Document 5 and Patent Document 6, the molten Al-Zn alloy coated steel sheet is a composite containing Mg and Sn is described. Patent Documents 5 and 6, the molten Al-Zn alloy coated steel sheet is described to be excellent in corrosion resistance after painting and / or processability.
[0011]
Patent Document 1: Japanese Patent 2003-253416 JP
Patent Document 2: Japanese Patent Publication 46-7161 discloses
Patent Document 3: Japanese Patent 2001-329383 JP
Patent Document 4: Japanese WO 2014 / 155944 Patent
Patent Document 5: Japanese Patent 2015-214747 JP
Patent Document 6: Japanese Patent 2002-180225 JP
Summary of the Invention
Problems that the Invention is to Solve
[0012]
　However, the outer panel with molten Al-Zn-based plated steel sheet described in Patent Document 2, (when exposed base steel) damage to the coating and the plating layer was when occurred, above-mentioned dendrite structure and inter due to the phase structure of the unique plating layer consisting of two tissue dendritic tissue, act as exposed base steel cathode, preferential dissolution of Zn in the plating layer (preferential corrosion of inter dendritic structure) coating film generated at the interface between the plating layer. This causes a swelling large coating film proceeds toward deep paint healthy portion, it is known that there is a problem that can not be suppressed erosion of the base steel.
　Moreover, inter-dendritic structure has a lower hardness than the dendritic structure. Therefore, due to the difference in hardness between the inter dendritic structure and dendritic tissue, during pressing deformation is concentrated at the inter dendritic structure. As a result, it is known to crack reaching the base steel to the plating layer. Since the base steel is corrosion at the crack vicinity portion exposed is promoted, in the conventional molten Al-Zn-based plated steel sheet, not only the coating film swelling occurs, was not able to suppress the erosion of the base steel.
[0013]
　Further, MgZn contained in the plating layer of the hot-dip Zn-Al-Mg plated steel sheet described in Patent Document 3 2 -phase is brittle. Therefore, when subjected to the plating steel sheet machining Zn / Al / MgZn 2 there is a possibility that results in a number of cracks starting from the ternary eutectic structure. To expose the base steel the cracks, there is a problem that can not be sufficiently suppressed erosion of the base steel in the vicinity of the still processing unit.
[0014]
　Further, the molten Al-Zn-based plated steel sheet described in Patent Document 4, the plating layer Mg is not contained in, is not any consideration attempts to reduce the corrosion rate of the plating layer itself. Therefore, from the viewpoint of long term inhibit erosion of the base steel, the sacrificial protection property is not be considered as satisfactory as plated steel sheet for automobiles.
[0015]
　Further, MgZn as a melt in the Al-Zn alloy coated steel sheet, not been sufficient study for controlling the plating tissue, brittle Mg intermetallic compound thus plating layer described in Patent Documents 5 and 6 2 There is estimated to form.
　In this case, the molten Al-Zn alloy coated steel sheet obtained is inferior in workability, is inferred that no further sacrifice corrosion resistance is also sufficient, cracks in the plating layer during press working. Therefore, the processing unit is expected that corrosion starting from the crack progresses.
　Erosion of base steel from the viewpoint of long term inhibiting, processability and sacrificial protection of these molten Al-Zn alloy coated steel sheet is not be considered as satisfactory as plated steel sheet for automobiles.
[0016]
　Therefore, conventionally, the molten Zn-plated steel sheet excellent in both workability and corrosion resistance after coating and sacrificial corrosion resistance has not been developed, were not especially exist plated steel sheet suitable as automotive applications.
[0017]
　Challenges One aspect of the present disclosure is to provide is to provide a plated steel sheet excellent in both workability and corrosion resistance after coating and sacrificial corrosion resistance.
Means for Solving the Problems
[0018]
　The means for solving the above problems includes the following aspects.
[0019]
<1>
　A plated steel sheet having a steel sheet, and a plated layer provided on at least part of the surface of the steel sheet,
　the plating layer is, in
　mass%, Al: 15%
　~ 60% Mg: 0.
　%
　~ 8.0 5% Sn:
　0.5% ~ 20.0% Si: 0.05% ~ 1.50%
　Bi: 0% ~ 5.0%, an In: 0% ~
　2.0%, Ca :
　0%
　~ 3.0%,
　Y: 0% ~ 0.5%, La: 0% ~
　0.5%, Ce: 0% ~ 0.5%, Cr: 0% ~
　0.25%, Ti :
　0%
　~ 0.25%,
　Ni: 0% ~ 0.25%, Co: 0% ~
　0.25%, V: 0% ~ 0.25%, Nb: 0% ~
　0.25%, Cu :
　0%
　~ 0.25%, Mn: 0%
　~ 0.25%, Sr: 0% ~ 0.5%,
　Sb: 0% ~ 0.5%, Pb: 0% ~
　0.5%, B : 0% to 0.5%,
　Contains, has a chemical composition and the balance being Zn and impurities,
　and the plating layer, the area fraction from 5 to 65% of the layered Mg 2 and Sn phase containing tissue, the tissue including a solid solution of Zn and Al has,
　the layered Mg 2 Sn phase containing tissue, Zn phase and the layered Mg having a thickness of less than 1 [mu] m 2 includes a Sn phase, the said laminar Mg 2 Sn phase the Zn phase a plurality of regions is the presence to that organization is divided into, plated steel sheet.
<2>
　in weight percent, plated steel sheet according to 0.5% to 3.0% content of Mg, the content of Sn is 1.0% to 7.5% <1>.
<3>
　in mass%, the content of Al is 20% to 60%, the content of Mg is 1.0% to 2.0%, the content of the Sn 1.0% to 5.0% , and plated steel sheet according to the content of the Si is 0.05% to 1.0% <1> or <2>.
<4>
　The content of the content and the Mg of the Sn is plated steel sheet according to any one of satisfying the following formula (1) <1> to <3>.
　Mg ≦ Sn ≦ 2.5 × Mg ··· Equation (1)
　In the formula (1), each element symbol represents the content of each element in weight percent.
<5>
　the layered Mg 2 -plated steel sheet according to Sn phase containing tissue area fraction of a 20% to 60% <1> to any one of <4>.
<6>
　the layered Mg 2 plated steel sheet Sn phase containing tissue area fraction of, according to any one of 30 to 60% <1> to <5>.
<7>
　plated steel sheet according to any one of the Zn and the area fraction of the tissue containing the solid solution of Al has 35% to 95% <1> to <6>.
<8>
　the plating layer is equivalent circle diameter 1μm or more bulk MgZn 2 -plated steel sheet according to any one of a 0% to 20% phase area fraction <1> to <7>.
<9>
　the plating layer is equivalent circle diameter 1μm or more bulk MgZn 2 -plated steel sheet according to any one of a 0% to 5% phase area fraction <1> to <8>.
<10>
　plated steel sheet of the plating layer, corresponds with 0% to 20% diameter 2μm or more bulk Zn phase in area fraction <1> according to any one of to <9>.
<11>
　plated steel sheet according to any one of the plating layer has 0-10% equivalent circular diameter 2μm or more bulk Zn phase in area fraction <1> to <10>.
<12>
　Plated steel sheet according to, any one of <1> to <11>, further comprising an interfacial alloy layer consisting of Al-Fe intermetallic compound having a thickness of 100 nm ~ 1.5 [mu] m between the plated layer and the steel sheet .
The invention's effect
[0020]
　According to one aspect of the present disclosure can provide a plated steel sheet excellent in both workability and corrosion resistance after coating and sacrificial corrosion resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021]
It is a [1] reflection electron image of the photographed SEM an example of the plating layer of the plated steel sheet according to the present disclosure (No.26 Example) 2000-fold (BSE images).
It is a [2] The region A in FIG. 1 the reflection electron image of the photographed SEM at 6000 times (BSE images).
No. [Figure 3] Example The plating layer of the plated steel sheet according to 24 is a reflection electron image of the photographed SEM at 2000 times (BSE images).
No. [Figure 4] Example The plating layer of the plated steel sheet according to 29, which is a reflection electron image of the photographed SEM at 2000 times (BSE images).
[FIG 5] Zn / Al / MgZn 2 is a ternary eutectic structure determination and reflected electron image of SEM of a cross section of the plating layer to the area fraction explaining a method of measuring (BSE images).
DESCRIPTION OF THE INVENTION
[0022]
　Hereinafter, an example of the present disclosure.
　In the present disclosure, the content of each element in the chemical composition shown in the "%" means "% by mass".
　Numerical ranges expressed using "to" means a range including numerical values described before and after "to" as the lower and upper limits.
　Numerical range when "super" or "less than" are assigned to the numerical values described before and after "to" means a range that does not include the lower limit or the upper limit value of these values.
　Content of the element of chemical composition, element content (e.g., Zn amount, Mg content, etc.) or elemental concentrations (e.g., Zn concentration, Mg concentration, etc.) may be referred to.
　The "flat portion corrosion resistance" indicates the corrosion hardly nature of the plating layer itself.
　The "sacrificial corrosion resistance", the base steel bare portion (cut end surface of example plated steel sheet, plating layer cracking unit during processing, and the peeling of the plating layer, portions of the base steel is exposed) the property of inhibiting corrosion of show.
　The "equivalent circle diameter", when observing a plating layer cross-section (taken along the cross section in the thickness direction of the plated layer), when the area defined by the contour of the phases, was considered a circle having the same area the diameter of a circle.
　The "C direction" indicates a direction perpendicular to the rolling direction of the steel sheet.
　The "L direction" indicates a direction parallel to the rolling direction of the steel sheet.
[0023]
　Plated steel sheet of the present disclosure includes a steel sheet, a plated layer provided on at least part of the surface of the steel sheet, a.
　Plating layer has a predetermined chemical composition. Also, the plating layer, the area fraction from 5 to 65% of the layered Mg 2 has a Sn phase containing tissue, tissue containing a solid solution of Zn and Al (hereinafter, for convenience, referred to as a "dendritic structure") and the.
　Then, the layered Mg 2 Sn phase containing tissue, and Zn phases, lamellar Mg having a thickness of less than 1 [mu] m 2 includes a Sn phase, the said laminar Mg 2 exist separately Sn phase the Zn phase into a plurality of regions it is to tissue.
[0024]
　Plated steel sheet of the present disclosure, the above-described configuration, the plated steel sheet excellent in both workability and corrosion resistance after coating and sacrificial corrosion resistance. Plated steel sheet of the present disclosure were found based on the following findings.
[0025]
　Inventors, automotive applications, suitable for coated steel sheet such as building materials, were studied workability after painting corrosion resistance and sacrificial corrosion resistance of the plating layer. As a result, we obtained the following findings.
　Mg intermetallic compounds, although a brittle phase, Mg 2 Sn phase MgZn 2 has a plastic deformability than the phase. The Mg 2 the Sn phase, a Zn phase having a plastic deformability, by the organization that exists separately Zn phase into a plurality of regions in layers, layered Mg 2 plastic deformability overall Sn phase containing tissues express, contributes to the improvement of workability.
　In addition, Mg 2 Sn phase becomes a source of Mg ions in a corrosive environment, for Mg ions to the insulating coating of the corrosion products, coatings corrosion under the painting state is suppressed. Although mechanism is not clear, layered Mg 2 In organizations with Sn phase are present separately Zn phase into a plurality of regions, corrosion layered Mg 2 travels along the Sn phase, resulting in a layered Mg 2 Sn phase There serve as a source of Mg ions for a long time. Then, Mg 2 Sn phase MgZn 2It is electrically baser than the phase, excellent essentially sacrificial protection property. Therefore, it is presumed to have the effect of improving the corrosion resistance after painting and the sacrificial corrosion resistance.
[0026]
　Therefore, a Zn phase, lamellar Mg having a thickness of less than 1 [mu] m 2 includes a Sn phase, the said laminar Mg 2 existing set of layered Mg divide the Sn phase the Zn phase into a plurality of areas 2 Sn phase content by the presence predetermined amount tissue in area fraction, processability and increases both the corrosion resistance after coating and sacrificial corrosion resistance. Specifically, the layered Mg 2 when the area fraction of the Sn phase containing tissue is 5% or more, than the commercial plated steel sheet, the corrosion resistance after coating, the higher the and the sacrificial protection property and processability.
[0027]
　By the above findings, the plated steel sheet of the present disclosure has been found to be a plated steel sheet excellent in both workability and corrosion resistance after coating and sacrificial corrosion resistance.
[0028]
　Furthermore, plated steel sheet of the present disclosure, because that is present in the plating layer of particulate layer dispersion tissue expressing plastic deformability, excellent chipping resistance can be realized longer life of the plated steel sheet after painting.
　Plated steel sheet of the present disclosure includes a predetermined amount of Al in the plating layer has a dendritic structure to increase the melting point of the plating layer. Therefore, excellent galling resistance can be suppressed adhesion to the press die of the plating layer during press molding. In other words, plated steel sheet of the present disclosure, it is possible to achieve both excellent corrosion resistance after painting and press formability.
[0029]
　It will be described in detail below plated steel sheet of the present disclosure.
[0030]
　First, a description will be given of steel plate.
　Steel plate becomes be plated is not particularly limited, Al-killed steel, very low carbon steel, high carbon steel, various high strength steels, Ni, various steel sheets such as Cr-containing steel can be used. Steelmaking process, the strength of the steel, hot rolling method, the pickling method, there is no special restriction on the pretreatment process of the steel sheet cold-rolled process, or the like.
[0031]
　Chemical composition of the steel sheet (C, Si, etc.) are not particularly limited. Ni contained in the steel sheet, Mn, Cr, Mo, Ti, elements such as B it is, has not been confirmed to affect the plating layer.
[0032]
　Next, a description will be given of a plating layer.
　First described the chemical composition of the plating layer.
　The chemical composition of the plated steel sheet comprises Al, Mg, Sn, and Si as essential elements, the balance being Zn and impurities. The chemical composition of the plated steel sheet, Bi, In, Ca, Y , La, Ce, Cr, Ti, Ni, Co, V, Nb, Cu, Mn, Sr, Sb, as optional elements at least one of Pb and B it may contain. In other words, any element may not contain.
　The content of each element of the plating layer means the average content of each element contained in the entire plating layer.
[0033]
[Al: 15% ~
　60%] Al is an essential element for improving the seizure resistance after painting corrosion resistance of the plating layer. Most Al present as Al phase in the interior of the dendritic structure in the plating layer. De
　dendritic structure to be described later is not passivated by the inclusion effect of Sn, in a state of not a factor to lower the corrosion resistance after coating. On the other hand, the metal in the plating layer is low melting point of the plating layer is baked stick that becomes a problem in the press die. However, as the Al concentration is high, the area fraction of the dendritic structure is a high melting point tissue is increased, therefore, possible to suppress the adhesion of the press die of the plating layer during press molding as a result (i.e., seizure improve per property that) becomes possible.
　Al concentration required to secure the area fraction of dendritic structure capable of expressing a sufficient seizure resistance is 15% or more. Therefore, the 15% lower limit of the Al concentration. Preferred Al concentration is 20% or more.
　On the other hand, when the Al concentration exceeds 60%, excessively grown is "interfacial alloy layer consisting of Al-Fe intermetallic compound" formed in the interface of the plating layer and the base steel to be described later, impairs workability. Therefore, the 60% upper limit of the Al concentration. Preferred Al concentration is 40% or less.
[0034]
[Mg: 0.5% ~
　8.0%] Mg is layered Mg 2 essential for the Sn phase containing tissue is formed in the plating layer to impart corrosion resistance after painting, the sacrificial protection property and processability to the plating layer it is an element. Mg is present as Mg intermetallic compound in plating layer elutes corrosive environment as Mg ions in a corrosive environment. Mg ion, a Zn-based corrosion products and insulating coating of, for barrier coating of rust. Thereby suppressing the invasion of corrosive factors to the plating layer and the coating film under can contribute to corrosion resistance after painting improves. Most Mg layered Mg 2 contained in the Sn phase containing tissue. Granular Mg 2 by formation of Sn phase containing tissues, corrosion resistance after painting, the sacrificial corrosion resistance and workability are improved. Corrosion resistance after painting, Mg concentration necessary to improve the sacrificial corrosion resistance and workability is 0.5%. Therefore, the 0.5% the lower limit of the Mg concentration. Preferred Mg concentration is 1.0% or more.
　On the other hand, if the Mg concentration exceeds 8.0%, the bulk MgZn below 2 phase is excessively formed, impairing workability. Therefore, the 8.0% upper limit of the Mg concentration. Massive MgZn impair the workability 2 from the viewpoint of suppressing the generation of phase, the preferred Mg concentration is set to 3.0% or less. More preferred Mg concentration is 2.0% or less.
[0035]
[Sn: 0.5% ~
　20.0%,] Sn is layered Mg with Mg 2 the Sn phase containing tissue is formed in the plating layer to impart corrosion resistance after painting, the sacrificial protection property and processability to the plating layer it is an essential element for. Further, Sn is, Zn / Al / MgZn 2 with ternary eutectic structure, bulk MgZn 2 is an element having also an effect of suppressing generation of phase.
　Therefore, Sn is corrosion resistance after painting to the plating layer, even an element enhancing the sacrificial protection property and processability.
　When the Sn concentration is low, the layered Mg 2 While Sn phase containing tissue is not easily formed, Zn / Al / MgZn 2 ternary eutectic structure and bulk MgZn 2 generation amount of phase is increased, corrosion resistance after painting of the plating layer , sacrificial corrosion resistance and workability tends to decrease. Therefore, the lower limit of the Sn concentration is 0.5%. Layered Mg 2 the Sn phase containing tissues sufficiently formed, Zn / Al / MgZn 2 ternary eutectic structure and bulk MgZn 2 from a sufficiently suppressing the generation of phase, the preferred Sn concentration is 0.1% or more . More preferred Sn concentration is 1.5% or more.
　On the other hand, when an excess of Sn concentration, Sn surplus crystallized out as a potentially noble Sn phase, it lowers the corrosion resistance after coating and the sacrificial corrosion resistance. Therefore, the upper limit of the Sn concentration is 20.0%. From the viewpoint of improving the corrosion resistance after painting, preferable Sn content is not more than 7.5%. More preferred Sn concentration is 5.0% or less.
[0036]
[Si: 0.05% ~
　1.50%] Si suppresses when contained in the plating bath, and Zn and Al contained in the plating bath, the reactivity of Fe element be plated elements it is. That, Si is plated layer and by controlling the reactivity of the steel matrix, affect the adhesiveness and workability of the plating layer composed of "Al-Fe intermetallic compound interface alloy layer (particularly, Fe 2 Al 5 is an essential element to control the formation behavior of the interfacial alloy layer) comprising or consisting of. minimum Si concentration required for inhibition of interfacial alloy layer is 0.05%.
　Si content If it is less than 0.05%, interfacial alloy layer is grown immediately after immersing be plated in the plating bath, the ductility imparting the plating layer is difficult, workability tends to decrease. Therefore, the lower limit of the Si concentration , 0.05%. the preferred Si concentration is more than 0.2%.
　on the other hand, when the Si concentration exceeds 1.50%, potentially noble Si phase remains to the plating layer, the corrosion acts as the cathode portion. as a result, the coating Leads to a decrease in Sogo corrosion resistance. Therefore, the upper limit of the Si concentration is 1.50%. The preferred Si concentration is 1.0% or less.
　In addition, Si is between metal and Mg in the plating layer Mg compounds 2 may exist as a Si phase, Mg 2 area fraction of Si phases is not more than 5%, no effect on performance.
[0037]
[Bi: 0 Pasento ～ 5.0
　Pasento] Bi is an element which contributes to the expense of corrosion resistance. Therefore, the lower limit of the Bi concentration is 0% greater than (preferably 0.1% or more, more preferably 3.0 or higher) is good.
　On the other hand, when the Bi concentration is increased, it tends to plating layer corrosion under the coating film, in the sense that the coating film swelling tends to be large, tends to corrosion resistance after coating is deteriorated. Therefore, the upper limit of the Bi concentration is 5.0% or less (preferably 0.5% or less, more preferably 0.1% or less) and.
[0038]
[An In: 0% ~
　2.0%] an In is an element which contributes to the sacrificial protection property. Therefore, the lower limit of the In concentration is 0% greater than (preferably 0.1% or more, more preferably 3.0 or higher) is good.
　On the other hand, when the In concentration is increased, it tends to plating layer corrosion under the coating film, in the sense that the coating film swelling tends to be large, tends to corrosion resistance after coating is deteriorated. Therefore, the upper limit of the In concentration is 2.0% or less (preferably 0.3% or less).
[0039]
[Ca: 0% ~ 3.0%] Ca
　is an element which can adjust the optimal Mg elution amount to impart corrosion resistance after painting and sacrificial corrosion resistance. Therefore, the lower limit of the Ca concentration is 0% greater than (preferably more than 0.05%) is better.
　On the other hand, when the Ca concentration increases, the processability tends to deteriorate. Therefore, the upper limit of the Ca concentration is 3.0% or less (preferably 1.0% or less).
[0040]
[Y: 0% ~ 0.5%]
　Y is an element which contributes to the sacrificial protection property. Therefore, the lower limit of the Y concentration is 0% greater than (preferably 0.1% or more) is good.
　On the other hand, when the Y concentration increases, the tendency for corrosion resistance after coating is deteriorated. Therefore, the upper limit of the Y concentration is 0.5% or less (preferably 0.3% or less).
[0041]
[La and Ce: 0% ~
　0.5%] La and Ce is an element contributing to the sacrificial corrosion resistance. Therefore, the lower limit of the La concentration and Ce concentrations, respectively, 0% greater than (preferably 0.1% or more) is good.
　On the other hand, when the La concentration and Ce concentration increases, the tendency for corrosion resistance after coating is deteriorated. Therefore, the upper limit of the La concentration and Ce concentration, respectively, and 0.5% or less (preferably 0.3% or less).
[0042]
[Cr, Ti, Ni, Co , V, Nb, Cu , and
　Mn: 0% ~ 0.25%] Cr, Ti, Ni, Co, V, Nb, Cu and Mn is the element contributing to the sacrificial protection property is there. Therefore, Cr, Ti, Ni, Co , V, Nb, the lower limit of the concentration of Cu and Mn, respectively, Si concentration exceeding 0 (preferably 0.05% or more, more preferably 0.1% or more) good .
　Meanwhile, Cr, Ti, Ni, Co , V, Nb, when the concentration of Cu and Mn increases, the tendency for corrosion resistance after coating is deteriorated. Therefore, Cr, Ti, Ni, Co , V, Nb, the upper limit of the concentration of Cu and Mn, respectively, and 0.25% or less.
[0043]
[Sr, Sb, Pb and B: 0%
　~ 0.5%] Sr, Sb, Pb and B is an element contributing to the sacrificial protection property. Therefore, Sr, Sb, the lower limit of the concentration of Pb and B, respectively, Si concentration exceeding 0 (preferably 0.05% or more, more preferably 0.1% or more) is good.
　Meanwhile, Sr, Sb, if the concentration of Pb and B increases, the tendency for corrosion resistance after coating is deteriorated. Therefore, the upper limit of the concentration of Sr, Sb, Pb and B, respectively, and 0.5% or less (preferably 0.1% or less).
[0044]
: [Balance Zn and impurities]
　balance of the chemical composition of the plating layer is a Zn and impurities.
　Zn, the sacrificial corrosion protection ability of the plating layer, the planar portion corrosion resistance, in order to properly secure a paint undercoating of a certain concentration or more, contained in the plated layer. These viewpoints, the chemical composition of the plating layer, the majority of Al and Zn.
　Impurities, components contained in the raw material, or a component mixed in the manufacturing process, refers to a do not have intentionally containing component. For example, the plating layer, by mutual atomic diffusion between the plating bath and the base steel (steel), as an impurity component such as Fe also be incorporated trace.
[0045]
　For example, by hot dipping, the case of forming a plating layer, the plating layer is sometimes contain certain Fe concentration as an impurity. Until Fe content of 3.0%, it has been confirmed no adverse effect on the performance included in the plating layer.
[0046]
[Chemical composition of the preferred plating layer]
　In the chemical composition of the plating layer, 0.5% to 3.0% content of Mg, it is preferable that the content of Sn is 1.0% 7.5% . When the Mg concentration and the Sn concentration in the above range, corrosion resistance after painting, the sacrificial corrosion resistance and workability is further improved.
　In particular, in the chemical composition of the plating layer, the content of Al is 20% to 60%, the content of Mg is 1.0% to 2.0%, and the content of said Sn is 1.0% to 5.0 %, and it is preferable that the content of the Si is 0.05% ~ 1.0%, Al concentration, Mg concentration, when the Sn concentration and the Si concentration in the above range, corrosion resistance after painting, the sacrificial corrosion resistance and processability sex can be further improved. In addition, further improved seizure resistance.
[Equation (1): Mg wt% ≦ Sn wt% ≦ 2.5 × Mg mass%]
　corrosion resistance after painting, in order to improve the sacrificial corrosion resistance and workability further particulate Mg 2 Sn phase containing tissue thoroughly formed, Zn / Al / MgZn 2 ternary eutectic structure and bulk MgZn 2 it is preferable to sufficiently suppress the formation of phases.
　Therefore, the content of the content and Mg of Sn is preferably satisfies the following formula (1), more preferably satisfies the following formula (2).
　Mg ≦ Sn ≦ 2.5 × Mg ··· Equation
　(1) 1.5 × Mg ≦ Sn ≦ 2.0 × mg · · · formula (2)
　Equation (1) to formula (2), the element symbol shows the contents of the elements in% by weight
[0047]
　Sn concentration did not satisfy the formula (1), if Sn is insufficient with respect to Mg, bulk MgZn 2 phase is formed, corrosion resistance after painting and sacrificial corrosion resistance tends to be low with processability.
　On the other hand, Sn concentration did not satisfy the formula (1), if Sn is excessive relative to Mg, potentially out noble Sn phase crystallizes, corrosion resistance and sacrificial corrosion resistance after painting tends to be low.
[0048]
　It will now be described metal structure of the plating layer.
　Plating layer, the layered Mg 2 has a Sn phase containing tissues, dendritic tissue (tissue comprising the solid solution of Zn and Al), the.
　Then, the plating layer is granular Mg 2 as Sn phase containing tissue other than the tissue, or equivalent circular diameter 1μm massive MgZn 2 phase, equivalent circular diameter 2μm or more bulk Zn phase, Zn / Al / MgZn 2 ternary eutectic structure there is a case of having a like.
[0049]
　Here, the reflection electron image of SEM of an example of the plating layer of the plated steel sheet of the present disclosure taken at 2000 times (BSE images) shown.
　As shown in FIG. 1, plated steel sheets, for example, a plating layer 1, and the steel plate 2, during the plating layer 1 and the steel plate 2 has an interfacial alloy layer 3 made of Al-Fe intermetallic compound, the ing.
　Tissue plating layer 1 is mainly laminar Mg 2 is composed of a Sn phase containing tissues 4 and dendrite structure 5. Further, as shown in FIG. 2 is an enlarged view of a region A in FIG. 1, Soshoyu Mg 2 Sn phase containing tissue 4, the layered Mg having a thickness of less than 1μm in Zn phase 6 2 Sn phase 7 there has been a tissue that is present so as to divide the Zn phase 6 into a plurality of regions.
　In Figure 1, dendritic tissue 5, together with the region shown in gray color, the area black indicated area surrounded corresponds. Color differences both regions, due to the difference of the Al concentration. Specifically, an area where dendrite structure 5 Al concentration is low is indicated by a gray color, an area dendrite structure 5 Al concentration was shown by high gray is shown in black.
　Note that in the plating layer 1, the layered Mg 2 Sn phase containing tissue 4 and besides dendritic structure 5, bulk MgZn 2 phase 10 (see FIG. 3), bulk Zn phase 9 (see FIG. 3), Zn / Al / MgZn 2 may have a ternary eutectic structure 8 (see Figure 3).
[0050]
Layered Mg 2 Sn phase containing tissues: the area fraction 5-65%]
　layered Mg 2 Sn phase containing tissue, and Zn phases, lamellar Mg having a thickness of less than 1 [mu] m 2 includes a Sn phase, the layered Mg 2 Sn phase are present separately the Zn phase into a plurality of regions.
　Layered Mg 2 Sn phase containing tissue, in the case where a plating layer was cross-section observation or surface observation, for example, a tissue present in the gap dendritic Zn phase. More specifically, in the case where a plating layer was cross-section observation or surface observation, with Zn phase which exists in the gap dendritic Zn phase structure, layered Mg having a thickness of less than 1 [mu] m 2 Sn phase and Zn phase into a plurality of regions is the presence to that organization is divided.
[0051]
　Here, the layered Mg 2 Sn phase, Mg present in the gap between the Zn phase structure together branched into dendritic 2 is Sn phase. By dendritic Zn phase structure with each other are in close contact, the layered Mg 2 Sn phase is the lamellar thickness of less than 1 [mu] m. Layered Mg 2 Sn phase is in the form of cover each dendrite Zn phase structure, as a result, has a shape divided Zn phase branches in dendritic into a plurality of regions.
[0052]
　Further, the layered Mg 2 it is necessary to solve problems of the present disclosure Sn phase is less than the thickness 1 [mu] m. Layered Mg as dendritic Zn phase structure divided finely 2 thickness of Sn phase becomes thinner. Layered Mg 2 is less than 1μm thickness of Sn phase, layered Mg 2 Sn phase containing tissue can be sufficiently exhibited plastic deformability. Incidentally, the layered Mg 2 Sn phase lower limit of the thickness is not particularly limited, for example, is 10nm or more.
[0053]
　In addition, if the cooling conditions of the process to be described later, the layered Mg 2 Mg occupied Sn phase containing tissue 2 area fraction of Sn phase becomes 10% or more. In this case, it is possible to improve the corrosion resistance while maintaining the plastic deformability. On the other hand, if not cooled by appropriate cooling conditions, Mg 2 area fraction of Sn phase is less than 10%, and, instead of the gaps between dendritic Zn phase structure, plate-shaped in the form of a mixture with coarse Zn phase mg 2 Sn phase is formed. In this case, Mg 2 becomes difficult to exhibit sufficient corrosion resistance since the amount of Sn phase is reduced. Thus, without cooling under appropriate cooling conditions, Mg 2 if the area fraction of the Sn phase is less than 10%, the tissue plate-like Mg 2 Sn phase containing tissue (Zn phase + plate Mg 2 Sn phase) was called layered Mg 2 distinguish Sn phase containing tissues.
[0054]
　The dendritic Zn phase structure plate Mg became coarse 2 Sn phase containing tissue, a small amount of Mg 2 because the stress in the Sn phase tends to concentrate, the layered Mg 2 plastic deformation as compared with the Sn phase containing tissue inferior in ability.
　The reason for this, is estimated as follows. Layered Mg 2 whereas Sn phase is provided so as to cover the respective fine dendrite Zn tissue, the plate-like Mg 2 Sn phase are present in a mixed state with the coarse dendrite Zn tissue. Therefore, the layered Mg 2 layered Mg in Sn phase containing tissue 2 while stress applied to the Sn phase is easily dispersed, a plate-like Mg 2 In Sn phase containing tissues, the plate-like Mg 2 stress tends to concentrate according to the Sn phase. Therefore, the plate-like Mg 2 Sn phase containing tissue, layered Mg 2 is presumed to poor plastic deformability as compared with the Sn phase containing tissue.
[0055]
　While not intending to be bound by theory, the layered Mg 2 Sn phase containing tissue, in the manufacturing process of the plating layer, Zn phase rapidly dendrite growth during final solidification, dendrite Zn phase adjacent Mg between branches 2 Sn phase is considered to be tissue formed solidifies in layers. In fact, the plating layer of the present disclosure, as shown in region B of FIG. 2, with a gap of dendrite structure 5, further dendrite growth Zn phase 6, the layered Mg around the Zn dendrites 2 Sn phase 7 it is possible to confirm the formation of the existing set of organizations. If such tissue was cross-section observation or surface observation of the plating layer, as shown in FIG. 1 and 2, the layered Mg 2 as an organization Sn phase 7 are present to divide the Zn phase 6 into a plurality of regions It is considered to be observed.
[0056]
　That is, the layered Mg 2 Sn phase containing tissue, the dendritic Zn phase, dendritic Zn phase branches layered Mg having a thickness of less than 1μm that exists between the 2 true and Sn phase, and is a tissue composed of .
　Here, the layered Mg 2 in Sn phase containing tissues, layered Mg 2 Sn phase containing tissue (i.e. Zn phase and the layered Mg 2 Sn phase) layered Mg for 2 that area fraction of Sn phase is 10-50% good. Further, the layered Mg 2 the average thickness of the Sn phase may be less than 0.01 ~ 1 [mu] m.
[0057]
　Layered Mg 2 average composition of the entire Sn phase containing tissue is not particularly limited, for example, Mg concentration of 1 to 10 mass%, Sn concentration of 1 to 25 mass%, Al concentration is 1 to 8 mass%, the balance There consisting Zn and about 2 wt% less impurities. Layered Mg 2 the composition of the entire Sn phase containing tissue can also include the optional elements that may be included in the chemical composition of the plating layer.
[0058]
　In the present disclosure, the particulate phase of the intermetallic compound corresponding to the following (1) to (5), layered Mg 2 regarded as Sn phase.
　(1) Mg was interstitial solid solution elements such as Si 2
　Sn (2) Mg 2 Sn phase Mg was transformed 9 Sn
　5 (3) Bi in a part of the Sn, In, Cr, Ti, Ni, Co, V, Nb, Cu, and at least one is substituted with substituted Mg of Mn 2 Sn and Mg 9 Sn 5 (Mg 2 Sn and Mg 9 Sn 5 of
　substituents) (4) Ca in a part of Mg, Y, La and substituted Mg for at least one Ce is substituted 2 Sn and Mg 9 Sn 5 (Mg 2 Sn and Mg 9 Sn 5 of
　substituents) (5) Ca in a part of Mg, Y, and at least one substitution of La and Ce, and Bi in a part of the Sn, In, Cr, Ti, Ni, Co, V, Nb, Cu, and substituted Mg for at least one is substituted for Mn 2 Sn and Mg 9 Sn 5 (Mg 2 Sn and Mg 9 Sn 5 substituted product)
[0059]
　Layered Mg 2 Sn phase containing tissue has an effect of improving corrosion resistance after painting and the sacrificial corrosion resistance, and processability.
　As described above, Mg is a brittle Mg intermetallic compound 2 but containing Sn phase, Mg 2 Sn phase MgZn 2 has a plastic deformability than the phase.
　As mentioned above, Mg-based intermetallic compound, although a brittle phase, Mg 2 Sn phase MgZn 2 has a plastic deformability than the phase. The Mg 2 the Sn phase, a Zn phase having a plastic deformability, by the organization that exists separately Zn phase into a plurality of regions in layers, express plastic deformability organization as a whole, processability It contributes to the improvement of.
　In addition, Mg 2 Sn phase becomes a source of Mg ions in a corrosive environment, for Mg ions to the insulating coating of the corrosion products, coatings corrosion under the painting state is suppressed. Although details of the mechanism is not clear, layered Mg 2 In organizations with Sn phase are present separately Zn phase into a plurality of regions, corrosion layered Mg 2 travels along the Sn phase, resulting in a layered Mg 2Sn phase serves as a source of Mg ions for a long time. Then, Mg 2 Sn phase MgZn 2 is electrically baser than the phase, excellent essentially sacrificial protection property. Therefore, it is presumed to have the effect of improving the corrosion resistance after painting and the sacrificial corrosion resistance.
　The layered Mg 2 Sn phase containing tissue by the corrosion resistance after coating, the sacrificial corrosion resistance and processability improving effect of the layered Mg present in the plating layer 2 increases the higher the Sn phase containing tissue area fraction of.
[0060]
　Layered Mg 2 when Sn phase containing tissue area fraction of less than 5%, corrosion resistance after painting, the effect of improving the sacrificial protection property and workability can not be obtained. Since layered Mg 2 and 5% the lower limit of the area fraction of Sn phase containing tissues. From the viewpoint of surely improving the corrosion resistance sacrificial corrosion resistance and workability after coating, the layered Mg 2 area fraction of Sn phase containing tissue is preferably 20% or more, more preferably 30% or more.
　On the other hand, as described above, the layered Mg 2 higher is the area fraction of the Sn phase containing tissues, corrosion resistance after painting, the effect of improving the sacrificial protection property and workability increase. Without limitation to the upper limit of the performance surface, on manufacturing constraints, it can generate layered Mg 2 area fraction of Sn phase containing tissue is 65% at maximum. Therefore, the layered Mg 2 upper limit of the area fraction of the Sn phase containing tissues is 65%. From the viewpoint of stable production, layered Mg 2 area fraction of Sn phase containing tissue is preferably 60% or less.
　That is, the layered Mg 2 area fraction of Sn phase containing tissue is 5 to 65%. Then, the layered Mg 2 area fraction of Sn phase containing tissue, preferably is 20-60%, more preferably 30 to 60%.
[0061]
[Dendritic organization: an area fraction of 35% to 95%
　dendritic structure is a tissue containing the solid solution of Zn and Al. Specifically, dendritic structure is a Al phase and Zn phase and finely divided tissue, Al concentration from 15 to 85%, a tissue exhibiting Zn concentration 15 to 85%. Therefore, dendritic tissue has an essentially plastic deformation capability, an organization that can contribute to improving the workability of the plating layer. In addition, there is also a contributing organization to the seizure improvement.
[0062]
　To ensure good workability, the area fraction of the dendritic structure is preferably at least 35%. From the standpoint of imparting to the plating layer superior workability, the area fraction of the dendritic structure is more preferably 40% or more. On the other hand, from a manufacturing standpoint, the upper limit of the dendritic structure is preferably 95%. In view of the particulate phase dispersed phase by improving corrosion resistance after painting and workability, dendritic structure is preferably 80% or less, more preferably 70% or less.
　That is, the area fraction of the dendritic structure is preferably 35 to 95%, more preferably 35 or 40 to 80%, more preferably 35 or 40% to 70%.
[0063]
[Massive Zn phase: an area fraction of 0% to 20%
　bulk Zn phase is present in amorphous in the plating layer, a Zn phase of 2μm or more bulk at equivalent circular diameter. The upper limit of the equivalent circular diameter of the bulk Zn phase is not particularly limited, for example, is 10μm or less.
　The higher the area fraction of the massive Zn phase, seizure resistance and corrosion resistance tend to decrease. Therefore, from the viewpoint of securing seizure resistance and corrosion resistance, the area fraction of the bulk Zn phase is preferably 20% or less. From the viewpoint of securing sufficient seizure resistance and corrosion resistance, the area fraction of the bulk Zn phase is more preferably 10% or less. Area fraction of bulk Zn phase 0 percent (most preferably free namely bulk Zn phase.) The most preferred
　words, the area fraction of the bulk Zn phase is preferably 0-20%, more preferably 0 to 10%, more preferably 0%.
[0064]
[Massive MgZn 2 : phase area fraction of 0% to 20%
　bulk MgZn 2 is phase was present in amorphous in the plating layer, a Zn phase of 2μm or more bulk at equivalent circular diameter. Bulk MgZn 2 maximum equivalent circle diameter of the phase is not particularly limited, for example, is 10μm or less.
　Bulk MgZn 2 phase is a brittle phase, likely to become the starting point of cracking at the time of processing. Then, in the vicinity of the crack corrosion is accelerated, which may become a cause of lowering the corrosion resistance after painting of the processing unit. Bulk MgZn 2 higher area fraction of phases, corrosion resistance after painting and workability tends to decrease. Therefore, from the viewpoint of securing corrosion resistance after painting and workability, bulk MgZn 2 area fraction of phases is preferably 20% or less. From the viewpoint of ensuring sufficient corrosion resistance after painting and workability, bulk MgZn 2 area fraction of phases is more preferably 5% or less. Bulk MgZn 2 area fraction of phases 0% (ie bulk MgZn most preferably 2 and most preferably does not contain the phase.)
　In other words, bulk MgZn 2 area fraction of phases is preferably 0 to 20% more preferably 0-5%, more preferably 0%.
[0065]
[Zn / Al / MgZn 2 ternary eutectic structure: an area
　fraction% ~ 3 0%] Zn / Al / MgZn 2 ternary eutectic structure is an Al phase, texture comprising Zn phase and MgZn phases. The shape of each phase, in order to change the size by chemical composition, shape is irregular. However, eutectic structure is at a constant temperature transformation, since the element moving during solidification is suppressed, to form a labyrinth that each phase shape, usually, each phase precipitates finely (see FIG. 5).
　Normally, each phase is, Zn phase is large, to form an island-like, then large MgZn phases, filled the gap Zn phase, Al phase, MgZn 2 an arrangement for distributed spots during phase it is often to take. Note that the chemical composition, phase constituting does not change, which precipitates in an island shape, MgZn 2 may become phase, Al phase or MgZn 2 might be a phase component of the immediately preceding coagulation positional relationship depending on the change.
　It will be described later particular method of ternary eutectic structure.
[0066]
　Zn / Al / MgZn 2 ternary eutectic structure is likely to progress of corrosion, brittle MgZn ternary eutectic structure in 2 tends phase becomes a starting point of cracking during processing. Then, in the vicinity of the crack corrosion is accelerated, which may become a cause of lowering the corrosion resistance after painting of the processing unit. Zn / Al / MgZn 2 as ternary eutectic structure area fraction of high corrosion resistance after painting and workability tends to decrease. Therefore, from the viewpoint of securing corrosion resistance after painting and workability, Zn / Al / MgZn 2 area fraction of the ternary eutectic structure is preferably 3% or less. From the viewpoint of ensuring sufficient corrosion resistance after painting and workability, Zn / Al / MgZn 2 area fraction of the ternary eutectic structure is most preferably 0% (i.e. Zn / Al / MgZn 2 contains ternary eutectic structure is most preferred.) that no
　other words, Zn / Al / MgZn 2 area fraction of the ternary eutectic structure is preferably 0-3%, most preferably 0%.
[0067]
　The thickness of the plating layer is, for example, lower than about 100 [mu] m. Since the plating layer total thickness depends on plating conditions, there is no particular limitation on the upper limit and the lower limit of the plating layer total thickness. For example, the thickness of the entire plating layer is in the conventional melt plating related viscosity and specific gravity of the plating bath. Furthermore the drawing speed and the wiping of the strength of the steel sheet (plating original plate), the plating amount is basis weight adjusted. Therefore, the lower limit of the plating layer total thickness is, for example, about 2 [mu] m. On the other hand, by the weight and uniformity of the plated metal can be fabricated by melt plating, the thickness of the plating layer is about 95 .mu.m.
　Therefore, the thickness of the plating layer may be a 2 ~ 95 .mu.m. -
[0068]
　Next, a description will be given interfacial alloy layer.
　Plated steel sheet of the present disclosure may further include an interface alloy layer consisting of Al-Fe intermetallic compound between steel and the plating layer. Usually, between the plating layer and steel sheet, generally interfacial alloy layer is formed consisting of the following Al-Fe intermetallic compound 3 [mu] m. However, depending on the formation conditions of the plating layer, interfacial alloy layer may not be formed.
　Interfacial alloy layer, in order to ensure adhesion of the plating layer and the base steel (steel plate) preferably has a thickness of at least 100 nm. On the other hand, Al-Fe-based intermetallic compound constituting the interfacial alloy layer are the brittle intermetallic compounds, there is a case where the thickness of the interfacial alloy layer reduces the chipping resistance exceeds 1.5 [mu] m.
　Therefore, if the plated steel sheet of the present disclosure having an interfacial alloy layer, it is preferable that the thickness of the interfacial alloy layer is 100 nm ~ 1.5 [mu] m.
　Incidentally, the interface alloy layer is in a state of solid solution Si, also has role in suppressing the alloying reaction of the plating layer and the base steel.
[0069]
　Here, the interface alloy layer consisting of Al-Fe intermetallic compound is, Al 5 Fe phase is a layer of the main phase. Al-Fe alloy layer is formed by mutual atomic diffusion base iron (steel) and the plating bath. However, interfacial alloy layer is partially, AlFe phase, Al 3 Fe phase, Al 5 Fe 2 in some cases, such as phase contains minor amounts.
[0070]
　Also, the interface alloy layer is a component of the plating layer, Zn, also including various elements such as Si. In particular, when Si is incorporated into the interfacial alloy layer to form a Al-Fe-Si intermetallic compound in the interface alloy layer.
　Further, interfacial alloy layer, when using various pre-plated steel sheet be plated may include a pre-plating components (e.g., Ni, etc.). When the pre-plating components (e.g., Ni, etc.) is taken into the interfacial alloy layer to form a Al-Fe-Ni intermetallic compound at the interface alloy layer.
[0071]
　In other words, interfacial alloy layer consisting of l-Fe intermetallic compound, Al 5 besides the alloy layer composed mainly of Fe phase, a layer comprising an alloy layer of the various embodiments.
[0072]
　Hereinafter, an example of a method for manufacturing a plated steel sheet of the present disclosure.
　Plated steel of the present disclosure, the surface of the plating original plate (i.e., one side or both sides) is obtained by forming a plating layer by a hot dipping method.
[0073]
Method for producing a plated steel sheet of the present disclosure, Zenjimia method, the pre-plating method, etc. are applicable. In the case of using Ni as a kind of pre-plating, there is a case where Ni is contained in it may be generated during the heating of the plating layer "interfacial alloy layer consisting of Al-Fe intermetallic compound."
[0074]
　Bath, so that the range of the chemical composition of the plating layer, to prepare a pure metal or alloy, for vatting dissolved in 450 ~ 650 ° C..
　Then, a plating original plate surface is sufficiently reduced, denominated Yokugo, immersed in the plating bath kept at a predetermined bath temperature, after pulling, cooled to form a plating layer on the surface of the plated original plate (steel plate) be able to. In order to control the coating weight of the plating layer, for example, N immediately after pulling up the be plated from the plating bath 2 implementing wiping by the gas.
[0075]
　Here, immediately after pulling up the be plated from the plating bath (i.e. plating temperature) the cooling rate of the temperature range from to 320 ° C. and below 10 ℃ / s, 20 ℃ the cooling rate of the temperature range up 280 ° C. from 320 ° C. / s or higher to be.
　Reflection electron image of the cross section of SEM of the plating layer of the present disclosure plated steel sheet shown in FIG. 1 (BSE images) until 280 ° C. The cooling rate of the temperature range from the plating bath temperature to 320 ° C. from 10 ℃ / s, 320 ℃ a reflection electron image of SEM of a cross section of the plating layer of the plated steel sheet and the cooling rate of the temperature range to produce a 40 ° C. / s of (BSE images).
　As shown in FIG. 1, when the cooling conditions, the plating layer, the layered Mg 2 tissue can be formed with a Sn phase containing tissue 4 and dendrite structure 5.
　The control of the cooling rate can be achieved by any method known to those skilled in the art. For example, a method of controlling the cooling rate by appropriately adjusting the flow rate of the cooling gas. In particular, when using a water-cooled, it is possible to achieve very high cooling rates in excess of 100 ° C. / s.
[0076]
　On the other hand, the cooling rate of the temperature range immediately after pulling up the be plated from the plating bath from (i.e. plating temperature) to 320 ° C. and 10 ° C. or less, the cooling rate of the temperature range up 280 ° C. from 320 ℃ 20 ℃ / s or higher even when the layered Mg in an amount sufficient when the Sn concentration is not proper 2 may not be formed the Sn phase containing tissue 4. For example, as shown in FIG. 3, when not adding the Sn, layered Mg in the plating layer 2 Sn phase containing tissue 4 is not formed, instead, dendritic tissue 5 with Zn / Al / MgZn 2 ternary eutectic structure 8 is formed.
[0077]
　Also, if you do not change the temperature region immediately after pulling up the be plated from the plating bath from (i.e. plating temperature) to 320 ° C., a temperature range of up to 280 ° C. from 320 ° C., the cooling rate between the above-mentioned range, sufficient a layered Mg amount 2 Sn phase containing tissue 4 may not be formed.
For example, as shown in FIG. 4, the cooling rate at a cooling rate condition is not changed in the above range, the particulate Mg in the plating layer 1 2 Sn phase containing tissue 4 is not formed, instead, the plate-like in Zn phase mg 2 Sn phase (thickness 0.2μm greater than mg 2 Sn phase) are mixed tissue 11 is formed. If the tissue 11 is formed, the area fraction of the plate Mg2Zn phase occupied in the tissue 11 is less than 25% more than 5%.
[0078]
　Detailed formation mechanism of the tissue 11 is not clear, it is believed as follows. Cooling rate A is 10 ° C. / s or less, Mg2Sn phase if the cooling rate B is less than 20 ° C. / s become coarse from lamellar to plate. Cooling rate A is less than 10 ° C. / s, when the cooling rate B is equal to or higher than 20 ° C. / s can not be solidified behavior which proceeds to the original non-equilibrium approach to equilibrium, Zn phase is dendrite growth. As a result, a thickness of 0.2μm ultra and area fraction plate-shaped Mg of less than 25% 2 are thought to form the Sn phase.
[0079]
　Hereinafter will be described a technique for analyzing the tissue of the molten Zn-plated steel sheet of the present disclosure.
[0080]
　Chemical composition of the plating layer is measured by the following method.
　First, obtain a calibration curve for quantitative analysis of each element in GDS (RF glow discharge spectroscopy). Then, to measure the depth direction of the chemical components of the plating layer of interest.
　Specifically, implement GDS (RF glow discharge spectroscopy) for a standard sample such as each element pure metal plate, obtaining a calibration curve showing the relationship between the advance element intensity plot and each element concentration.
　On the other hand, a 30mm square and several pieces taken from a sample of plated steel sheet to be measured, and GDS sample. From the surface of the plating layer was performed with argon ions sputter obtain elemental intensity plot in the depth direction. The calibration curve is converted into elemental concentrations from the resulting intensity plot.
　Analysis of chemical composition by the GDS, the analyzed area φ4mm above, the sputtering rate as the range of 0.04 ~ 0.1 [mu] m / sec, measuring more than 10 points. Each element concentration of chemical composition, the average value of the element concentration in each location.
　However, in each of the GDS analysis points, in order to remove the influence of the outermost layer of the oxide layer, ignoring the component plot of the surface layer 1μm depth, depth 1 to the average value of each element concentration of 10 [mu] m (5 [mu] m width) the adopted.
[0081]
　Organization of the plating layer (however, Zn / Al / MgZn 2 area fraction of the ternary eutectic structure is excluded) is measured by the following method.
　The measurement of the area fraction of the tissue of the plating layer, using the FE-SEM equipped with EDS (energy dispersive X-ray analyzer).
[0082]
　From plated steel sheet, cutting the sample piece having a C direction 25 mm × L direction 15mm cross section (cross section cut in the thickness direction of the plated layer). The obtained test pieces embedded in a resin, CP (cross session polisher) to the cross section of the plating layer to be measured is subjected to machining. After CP processing, to produce an element mapping images by the reflected electron image and EDS of SEM of the cross section of the plating layer. Elemental mapping images by the reflected electron image and EDS of the SEM, magnification 5000 times, of the visual field size: a longitudinal 50 [mu] m × horizontal 200 [mu] m.
　Based on the element mapping images by the reflected electron image and EDS of SEM, to identify regions of the tissue.
[0083]
　Next, it is determined in the reflection electron image of SEM, lightness of the gray scale indicated by each organization having the plating layer, the three values ​​of hue and contrast values. Lightness each tissue exhibits, three values ​​of hue and contrast value, since it reflects the atomic number of the elements contained in the tissue, usually atomic number is small Al content, the more the phase content of the Mg content is large, black the exhibits, as Zn amount is large phase, tend to exhibit a white color.
[0084]
　Only the range of the three values ​​indicated by each tissue included in the plating layer, to implement the computer image processing, such as color change (e.g., a particular tissue only, so as to display a white image, the area of ​​each tissue in the field of view calculating the (number of pixels) and the like). By performing the image processing in each phase, determine the area fraction of each tissue in the coating layer occupied in the backscattered electron image of SEM.
[0085]
　The area fraction of each tissue of the plating layer, in any five visual fields of the cross section (cross section cut in the plating layer thickness direction) of the plating layer, the average value of the area fraction of each tissue was determined by the operation .
[0086]
　Here, the layered Mg 2 area fraction of Sn phase containing tissue, the Zn phase region, the layered Mg having a thickness of less than 1 [mu] m 2 was in Zn phase Sn phase are present separately Zn phase into a plurality of regions Te, layered Mg 2 is the area fraction of the Sn phase, including the Zn phase.
　Area fraction of dendritic organization, a solid solution of Zn and Al (Al concentration from 15 to 85%, Zn concentration 15 to 85% are shown tissue) is the area fraction of the area occupied by the.
　Bulk MgZn 2 area fraction of phases is equivalent circular diameter 1μm or more MgZn 2 is the area fraction of phases.
　Area fraction of bulk Zn phase is the area fraction of the equivalent circular diameter 2μm or more Zn phase.
[0087]
　Incidentally, the layered Mg 2 Sn phase containing tissue (i.e. Zn phase and the layered Mg 2 Sn phase) layered Mg for 2 Measurement of area fraction of Sn phase occupied, magnification 10000 times, plating layer was size 12 [mu] m × 12 [mu] m field of view except that the backscattered electron image of a cross section of SEM and measured is measured by the same method.
　Further, the layered Mg 2 the average thickness of the Sn phase in the reflected electron image of the same SEM, 5 layered Mg field of view (5 points per field) 2 is calculated as an average value obtained by measuring the thickness of the Sn phase.
[0088]
　Zn / Al / MgZn in the plating layer 2 Identification and area fraction of the ternary eutectic structure is measured by the following method.
[0089]
　First, in the same manner as the measurement of the area fraction of each tissue in the coating layer, a reflective electron image of SEM, Al phase, Zn phase and MgZn 2 three phases of phase to identify the tissue eutectic. A portion of the tissue, a magnification of 30,000, size 3 [mu] m × 4 [mu] m (diagonal, 5 [mu] m) is observed in a rectangular field of view (see FIG. 5). At this time, in the rectangular field of view, when minus diagonal two, one diagonal per Zn phase five times or more, and Zn phases extending around MgZn 2 phase and Al phase 5 times or more, if the diagonal crosses , it determined to be a three-way eutectic structure. This judgment is the reference that the ternary eutectic structure unique is "each three phases finely dispersed tissue."
[0090]
　Incidentally, the possibility that the ternary eutectic structure is unevenly distributed, or ternary eutectic structure is formed hard composition, the ternary eutectic structure is, if it is not possible to the region of 3 [mu] m × 4 [mu] m, the 1μm square lattice pattern to the organization the separator, if each phase in the lattice is contained 1 or more, it is determined that the ternary eutectic structure.
[0091]
　Then, the reflected electron image (5000 magnification, field of view size: length 50 [mu] m × horizontal 200 [mu] m) of the same SEM and measurement of the area fraction of each organization in the coating layer with respect to, repeat the above operation, three-way while confirming the continuity of the eutectic structure, to grasp the ternary eutectic structure of the contour (area). Then, determine the area fraction of the ternary eutectic structure in the coating layer occupied in the backscattered electron image of SEM was grasped.
　The area fraction of the ternary eutectic structure is in any of at least five visual fields of the cross section (cross section cut in the plating layer thickness direction) of the plating layer, the area fraction of the ternary eutectic structure obtained by the above operation an average value.
[0092]
　Bulk MgZn 2 mean equivalent circular diameter of the phase, and bulk Zn phase is measured by the following method.
　When measuring the area fraction of the tissue, in the reflection electron image of SEM was identified organizations, among the identified phase, selects a phase with a top 5 equivalent circular diameter. Then, the operation was carried out five fields of view, the arithmetic mean of the total of 25 equivalent diameter, bulk MgZn 2 phase, and an average equivalent circular diameter of the bulk Zn phase.
[0093]
　The thickness of the interfacial alloy layer consisting of Al-Fe intermetallic compound is determined as follows.
　When measuring the area fraction of the tissue, the reflection electron image of SEM identified each tissue (5000 magnification, field of view size: length 50 [mu] m × horizontal 200 [mu] m, however, the field of view interfacial alloy layer is visually recognized. in), for any five points of the identified interface alloy layer, to measure the thickness. Then, the arithmetic mean of five positions to the thickness of the interfacial alloy layer.
[0094]
　The following describes the post-processing that can be applied to the plated steel sheet of the present disclosure.
　The plated steel sheet of the present disclosure, the film may be formed on the plating layer. Coating can form one or more layers. The type of film immediately above the plated layer, for example, chromate film, phosphate film include chromate-free coatings. Forming these films, chromate treatment, phosphate treatment, chromate-free treatment may be carried out by known methods.
[0095]
　The chromate treatment, electrolytic chromate treatment to form a chromate film by electrolysis, by using the reaction with the material to form a film, then washing out the excess treatment liquid reaction type chromate treatment was applied to the treatment liquid to the object to be coated there are dried coating type chromate treatment to form a film without washing with water. It may be adopted any of the processing.
[0096]
　The electrolytic chromate treatment, chromic acid, silica sol, resin (phosphoric acid, acrylic resin, vinyl ester resin, a vinyl acetate acrylic emulsion, carboxylated styrene butadiene latex, diisopropanolamine modified epoxy resin), and an electrolyte that uses a hard silica it can be exemplified chromate treatment.
[0097]
　The phosphate treatment, for example, zinc phosphate treatment, zinc phosphate calcium treatment, can be exemplified manganese phosphate treatment.
[0098]
　Chromate-free treatment is particularly suitable without impact on the environment. The chromate-free treatment, electrolytic chromate-free treatment to form a chromate-free coating by electrolysis, by using the reaction with the material to form a film, then, the reaction type chromate-free treatment to wash away the excess treatment liquid, the treatment liquid there are dried coating type chromate-free treatment to form a film without washing with water was applied to the object to be coated. It may be adopted any of the processing.
[0099]
　Further, on the film immediately above the plated layer may have an organic resin film one layer or two or more layers. As the organic resin is not limited to a specific type, for example, polyester resins, polyurethane resins, epoxy resins, acrylic resins, polyolefin resins, or modified products thereof and the like resins. Here modified products and is a reactive functional group contained in the structure of these resins were reacted and other compounds containing a functional group in the structure capable of reacting with a functional group (such as a monomer or a crosslinking agent) It refers to the resin.
[0100]
　Examples of such an organic resin may be used by mixing one or more organic resins (those not denatured), in the presence of at least one organic resin, at least one other the organic resin obtained by modifying an organic resin may be used alone or in combination. And it may include any coloring pigments and anticorrosive pigments in the organic resin film. Those water reduction by dissolving or dispersing in water can also be used.
Example
[0101]
　It is shown below as examples as an example of the present disclosure.
[0102]
　As the plating bath, the chemical composition of the plating layer has bath preparation the plating bath components adjusted so as to chemical composition shown in Table 1. Plating bath temperature depending on the composition, it was 465 ~ 595 ° C.. As it is plated, using a hot-rolled steel sheet having a thickness of 0.8 mm (carbon concentration of 0.2%). Original sheet, after cutting into 100 mm × 200 mm, plated with molten plating test apparatus-house batch. The sheet temperature was monitored using a thermocouple spot welded to be plated center. Further, in Table 1, a case satisfying the expression (1) is a composition balance of Mg and Sn disclosed disclosure OK, a case not satisfying described as NG.
[0103]
　Before plating bath immersion, N oxygen concentration in the following furnace 20 ppm 2 -5% H 2 gas, reducing the plated original plate surface of 800 ° C., N 2 in air and immersed plate temperature is bath temperature + 20 ° C. with gas reached
after was about 3 seconds immersed in the plating bath. After the plating bath immersion, it was pulled up by pulling speed 100mm / sec. During withdrawal, N 2 was coating weight adjustment by wiping gas.
[0104]
　After withdrawal of the steel plate from the plating bath, and cooled from the plating bath temperature of the plating layer under the conditions shown in Table 1 to room temperature to prepare a plated steel sheet.
　Incidentally, (No.101 in Table 1) Commercially available hot-dip galvanized steel sheet, (No.102 in Table 1) alloyed galvanized steel sheet, and to prepare the electro-galvanized steel sheet (No.103 in Table 1) , it was evaluated for the above.
[0105]
[Table 1-1]

[0106]
[Table 1-2]

[0107]
[Table 1-3]

[0108]
[Table 1-4]

[0109]
[Table 1-5]

[0110]
[Table 1-6]

[0111]
[Table 1-7]

[0112]
[Table 1-8]

[0113]
　Conducted the following measurement and evaluation for the coated steel sheet produced in each example are shown in the list in the above Table 1.
[0114]
- the area fraction of the measurement of each tissue -
　the area fraction below the tissue of the plating layer of the obtained coated steel sheet was measured according to the method described above.
· Layered Mg 2 Sn phase containing tissue (in the table, "lamellar phase containing tissue" hereinafter)
, dendritic tissue
-Zn / Al / MgZn 2 ternary eutectic structure
, equivalent circular diameter 1μm or more bulk MgZn 2 phase
-equivalent circle diameter 2μm or more bulk Zn phase
plate-like Mg in · Zn phase 2 plate of Mg Sn phase are mixed 2 Sn phase containing tissue (in the table, "Zn phase + plate Mg 2 denoted Sn
phase") · Sn phase
- Si phase
-Mg 2 Si phase
, the tissue other than the intermetallic compound phase (in the table referred to as "other phase" ")
[0115]
- Measurement of Average equivalent circle diameter of each tissue -
　a mean equivalent circular diameter below the tissue of the plating layer of the obtained coated steel sheet was measured according to the method described above. However, in Table 1, the average equivalent circle diameter is referred to as "equivalent circular diameter".
- equivalent circular diameter 1μm or more bulk MgZn 2 phase
-equivalent circular diameter 2μm or more massive Zn phase
-Sn phase
, Si phase -Mg
2 Si phase
[0116]
- thickness measurements of interfacial alloy layer -
　the thickness of the interfacial alloy layer of the obtained coated steel sheet was measured according to the method described above.
[0117]
- Layered Mg 2 Sn phase containing tissue average thickness and area fraction of lamellar MgSn phase -
　No. shown in Table 1 To give 26 of the reflected electron image of SEM and (BSE images). No. shown in Table 1 26 reflection electron image of SEM of the (BSE images) shown in FIGS. As apparent from FIG. 1, the plating layer 1 is mainly granular Mg 2 was composed of Sn phase containing tissue 4 and dendrite structure 5. Then, the granular Mg shown in FIG. 2 2 layered Mg formed in Sn phase containing tissue 4 2 average thickness and area fraction of Sn phase 7 (layered Mg 2 Sn phase containing tissue (i.e. Zn phase and the layered Mg 2 Sn phase ) layered Mg for 2 was examined area fraction of Sn phase).
　Similarly, for the other samples, the layered Mg 2 was examined an average thickness and area fraction of Sn phase. As a result, the layered Mg 2 layered Mg formed in Sn phase containing tissue 2 representative value of the average thickness and area fraction of Sn phase was shown in the table below 2.
[0118]
[Table 2]

[0119]
- bending workability -
　Evaluation of bending workability of the plating layer was performed in the following street.
　From the obtained plated steel sheets were cut test piece C direction 30 mm × L direction 60 mm (L). The test pieces were 180 ° bend (1T bending) in the C direction, the top of the working portion of the plating layer observed by SEM were counted number of cracks present on the top portion (1.6 mm × 30 mm).
　Four sandwiched specimen test piece inside the DoitaAtsu, six sandwiched specimen test piece inside the DoitaAtsu, and each 180 ° bend in the direction C (6T bending and 6T bending), Similarly, it counted number of cracks.
　Then, each plated steel sheet at least 3 samples prepared, calculates the average value of existing cracks was evaluated bending workability. Write number of cracks average is small, excellent in plastic deformability, bending property can be evaluated as good.
　Evaluation criteria "A" if the average number of cracks is a Crackless 0 present present, the case where the average number of cracks of 1 to 20 present "B", the average number of cracks the case between 21 and 100 " C ", the average number of cracks was not less than 101 present a" D ".
[0120]
- Evaluation of corrosion resistance after painting -
　Evaluation of corrosion resistance after painting of the plating layer was performed in the following street.
　From the obtained plated steel sheets were taken test piece C direction 50 mm × L direction 100 mm. The plating layer surface of the test piece, Zn phosphate treatment: subjected to (SD5350 system Nippon Paint Industrial coding manufactured by standard).
　Then, the plating layer surface of Zn phosphate treated test piece, electrodeposition coating -: by (PN110 POWERNICS gray Nippon Paint Industrial coding Inc. standard), to form a coating film having a thickness of 20 [mu] m, the baking temperature 150 ° C., subjected to baking of the coating at 20 minutes to form a electrodeposition coating film.
　Next, put the base steel crosscut scratches reaching the (steel) (40 × √2 2 pieces) with respect to electrodeposition coating film of the test piece.
　The obtained test pieces were subjected to combined cycle corrosion test in accordance with JASO (M609-91). Then, measure the maximum swelling width of the cross-cut around eight after each lapse of 30,60,90,150 cycle, the average value was determined.
　It was to evaluate the corrosion resistance after painting by this blistering width. The evaluation criteria, at the time of the number of cycles of 30,60,90,150 cycle JASO (M609-91), "A" if the blister width from the cross cut scratches of 1mm or less, in the case of the following 1mm beyond ~ 2mm was "B", in the case of less than 2mm beyond ~ 4mm "C", if the red rust occurs "D".
[0121]
- Evaluation of corrosion resistance after painting -
　Evaluation of sacrificial protection of the plating layer was performed in the following street.
　From the obtained plated steel sheets were taken test piece C direction 50 mm × L direction 100 mm. The plating layer surface of the test piece, Zn phosphate treatment: subjected to (SD5350 system Nippon Paint Industrial coding manufactured by standard).
　Then, the plating layer surface of Zn phosphate treated test piece, electrodeposition coating -: was performed at 20μm the (PN110 POWERNICS gray Nippon Paint Industrial coding Inc. standard), baking temperature 0.99 ° C., for 20 minutes and baked to form a electrodeposition coating film.
　Then, crosscut scratches (40 × √2 2 present) to reach the base steel against electrodeposition coating film of the test piece.
　The obtained test pieces were subjected to combined cycle corrosion test in accordance with JASO (M609-91). After each test the 30,60,90,150 cycle, the corrosion depth of the base steel was measured by a micrometer, and the average value was obtained.
　It was to evaluate the corrosion resistance after painting by the erosion depth. The evaluation criteria at the time of the number of cycles of 60,120,240,360 cycles each JASO (M609-91), if the base steel corrosion depth from the cross-cut scratch is less than 0.1mm "A", 0 when it is less than .1mm above-0.3mm and "B", in the case of 0.3mm or more and less than 0.4 mm "C", in the case of more than 0.4mm "D".
[0122]
- chipping resistance evaluation -
　chipping resistance of the plating layer was performed in the following street.
　In the same manner as in the evaluation of the corrosion resistance after coating, were prepared test pieces subjected to electrodeposition coating in the plated layer surface. The electrodeposition coating film surface of the test piece, further intermediate coating was performed topcoat, a clear paint, the film thickness as a whole to form each coating film so as to be 40 [mu] m.
　Using Gurabero tester (manufactured by Suga Test Instruments Co., Ltd.), 3.0 kg / cm No. 7 crushed stone 100g from a distance of 30 cm 2 at an air pressure of an angle of 90 degrees to the coating film of the cooled specimen -20 ° C. in was a collision. Then, by using the adhesive tape to expose the peeling of the plating layer at a collision portion, the diameter of the peeled portion was measured, and the average value was defined as an average peel diameter to choose five from the largest of the peeling diameter.
　The average peel diameter, was evaluated chipping resistance. Higher average peel diameter is smaller, the better the chipping resistance.
　Evaluation criteria average when peeling diameter is less than 1.0mm "A", the case where the average peel diameter of less than 1.5mm or 1.0mm "B", less than the average peel diameter 1.5mm to 3.0 "C" in the case of an average peeling diameter was equal to or larger than 3.0mm and "D".
[0123]
- seizure resistance evaluation -
　seizing resistance of the plating layer was performed in the following street.
　From the obtained plated steel sheets were taken test piece C direction 80 mm × L direction 350mm by two, respectively. Subjected to drawbead processed using jig which imitates a die and a bead on the two test pieces was generated length 150mm or more sliding between the plating layer forming surface and the die shoulder and the bead portion of the test piece . Incidentally, the respective stations radii of the die shoulder and the bead portion of the jig used in the test 2mmR and 5MmR, pressing pressure of the die 60KNm 2 , drawing speed of drawbead processing was 2m / min. Further, at the time of the test, the lubricating oil on the surface of the test piece: 10 mg / m on both sides of (550S Nippon Parkerizing Co., Ltd.) 2 was applied.
[0124]
　Then, Width: 80 mm × length: the primary test piece 350mm were taken every two respectively, this applies drawbead processed using jig which imitates a die and a bead, surface-treated surface of the steel sheet and the die shoulder and the bead It raises the length 150mm or more sliding between the parts, to evaluate the seizure resistance. Incidentally, the respective stations radii of the die shoulder and the bead portion of the jig used in the test 2mmR and 5MmR, pressing pressure of the die is 60 kN / m 2 , the drawing speed of the drawbead processing was 2m / min. Further, at the time of the test, the lubricating oil on the specimen surface: 0.5 g / m on both sides of (550S Nippon Parkerizing Co., Ltd.) 2 was applied.
　Evaluation criteria a case where the plating layer to the die and the bead in the visual is not seizure "A", "B" where the plating layer on the die and the bead minor although seizure in visually plated die and the bead in the visual layers were the case seizure is marked as "D".
DESCRIPTION OF SYMBOLS
[0125]
　1 plated layer
　2 steel
　3 interfacial alloy layer
　4 layered Mg 2 Sn phase containing tissue
　5 dendrite structure
　6 Zn phase
　7 layered Mg 2 Sn phase
　8 Zn / Al / MgZn 2 ternary eutectic structure
　9 bulk Zn phase
　10 mass MgZn 2 phase
　the plate Mg in 11 Zn phase 2 tissue Sn phase are mixed
　20: Zn / Al / MgZn 2 ternary eutectic structure of Zn phase
　21: Zn / Al / MgZn 2 ternary eutectic structure of MgZn 2 phase
　22 : Zn / Al / MgZn 2 Al phase of the ternary eutectic structure
[0126]
　Japanese disclosure of patent application 2017-053148 its entirety is incorporated herein by reference.
　All documents described herein, patent applications, and technical standards, each individual publication, patent application, and that the technical specification is incorporated by reference to the same extent as if marked specifically and individually, It incorporated by reference herein.

The scope of the claims

[Requested item 1]And the steel sheet, a plated steel sheet having a plating layer provided on at least part of the surface of the steel sheet,
　the plating layer is, in
　mass%, Al:
　15% ~ 60% Mg: 0.5% ~
　% 8.0
　Sn:
　0.5% ~ 20.0% Si: 0.05% ~ 1.50%
　Bi: 0% ~ 5.0%, an In: 0% ~
　2.0%, Ca: 0%
　3.0% ~,

　Y: 0% ~ 0.5%, La: 0% ~
　0.5%, Ce: 0% ~ 0.5%, Cr: 0% ~
　0.25%, Ti: 0%
　0.25%

　Ni:~, 0% ~ 0.25%, Co: 0% ~
　0.25%, V: 0% ~ 0.25%, Nb: 0% ~
　0.25%, Cu: 0%
　0.25%
~,
　0% ~ 0.25%, Sr: 0% ~ 0.5%,
　Sb: 0% ~ 0.5%, Pb: 0% ~
　0.5%, B: 0% to 0.5 percent,
　Contains, has a chemical composition and the balance being Zn and impurities,
　and the plating layer, the area fraction from 5 to 65% of the layered Mg 2 and Sn phase containing tissue, the tissue including a solid solution of Zn and Al has,
　the layered Mg 2 Sn phase containing tissue, Zn phase and the layered Mg having a thickness of less than 1 [mu] m 2 includes a Sn phase, the said laminar Mg 2 Sn phase the Zn phase a plurality of regions is the presence to that organization is divided into, plated steel sheet.
[Requested item 2]
　By mass%, plated steel sheet according to claim 1, wherein the content of Mg is 0.5% to 3.0%, the content of Sn is 1.0% to 7.5%.
[Requested item 3]
　In mass%, the content of 20% to 60% of Al, the content is 1.0% to 2.0% of Mg, the content of 1.0% to 5.0% of the Sn, and the plated steel sheet according to claim 1 or claim 2 content of Si is 0.05% to 1.0%.
[Requested item 4]
　Plated steel sheet according content of content and the Mg of the Sn is in any one of claims 1 to 3 satisfying the following formula (1).
　Mg ≦ Sn ≦ 2.5 × Mg ··· Equation (1)
　In the formula (1), each element symbol represents the content of each element in weight percent.
[Requested item 5]
　The layered Mg 2 plated steel sheet according to Sn phase containing tissue area fraction of any one of claims 1 to 4 is 20% to 60%.
[Requested item 6]
　The layered Mg 2 plated steel sheet Sn phase containing tissue area fraction of, according to any one of claims 1 to 5 is 30% to 60%.
[Requested item 7]
　Plated steel sheet according to any one of claims 1 to 6 wherein the Zn and an area fraction of the tissue containing the solid solution of Al, with 35% to 95%.
[Requested item 8]
　The plating layer is equivalent circle diameter 1μm or more bulk MgZn 2 -plated steel sheet according to any one of claims 1 to 7 having 0% to 20% phase area fraction.
[Requested item 9]
　The plating layer is equivalent circle diameter 1μm or more bulk MgZn 2 -plated steel sheet according to any one of claims 1 to 8 having 0% to 5% phase area fraction.
[Requested item 10]
　Plated steel sheet according to any one of claims 1 to 9 wherein the plating layer is, having 0-20% equivalent circular diameter 2μm or more bulk Zn phase in area fraction.
[Requested item 11]
　Plated steel sheet according to any one of the plating layer, claims 1 to 10 having from 0% to 10% equivalent circular diameter 2μm or more bulk Zn phase in area fraction.
[Requested item 12]
　Between the plated layer and the steel sheet, plated steel sheet according to any one of claims 1 to 11, further comprising an interfacial alloy layer consisting of Al-Fe intermetallic compound having a thickness of 100 nm ~ 1.5 [mu] m.