Adhesive bonded structure

Abstract

Provided is an adhesively bonded structure which exhibits more excellent adhesion durability while maintaining red rust resistance. [Solution] This bonded structure has a first member, a second member, and an adhesive layer that bonds the first member and the second member, the first member being a plated steel member that has a steel member and a plating layer having a prescribed chemical composition, and the surface structure of the plating layer having a surface structure in which the surface structure of the plating layer has a surface structure in which the surface structure of the steel member has a surface structure in which the surface structure of the steel member has a surface structure in which the surface structure has a surface structure in which the surface structure has a surface structure. The average area ratio of an [alpha]-precipitated [eta] phase, which is a metallographic structure in which the [alpha] phase is precipitated in the [eta]-parent phase, is 5-95%, and a cross-section obtained by cutting the bonded structure in the lamination direction of the first member, the second member, and the adhesive layer is observed with an electron microscope. The ratio L / L0 is 1.10 or more, where L is the bonding length, which is the sum of the lengths of contact between the plating layer or the steel member and the adhesive layer, and L0 is the length of the field of view in the direction orthogonal to the surface normal direction of the steel member.

Description

Technical Field

[0001] The present invention relates to adhesively joined structures. Background Art

[0002] In the automotive and other transportation equipment industries, the use of adhesives for joining components is increasing for purposes such as improving vehicle body rigidity, assisting with weld fracture, and joining dissimilar materials. Significant performance improvements can be expected by joining components together using adhesives, making the use of adhesives an important tool for lightweighting vehicle bodies. Consequently, various studies are underway to develop adhesively bonded structures that use adhesives to join metal components together or to other materials, with the goal of increasing the joint strength between components.

[0003] For example, in the following patent document 1, the following technical idea is disclosed: in an adhesively bonded structure in which a first component having a metal part and a second component are bonded by means of an adhesive layer, in order to improve the bonding durability, a specific coating layer is provided on at least a portion of the surface of the metal part of the first component, and then the first component and the adhesive layer are bonded by means of the coating layer.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2020 / 067430 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] The present inventors have studied the adhesively bonded structure disclosed in Patent Document 1 and have found that improvement is still desired with respect to the technique disclosed in Patent Document 1 from the viewpoint of achieving even better adhesive durability.

[0009] Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an adhesively bonded structure that maintains red rust resistance and exhibits further excellent bonding durability.

[0010] Solutions for solving problems

[0011] The present inventors conducted intensive studies to solve the above-mentioned problems and found that better bonding durability can be achieved by controlling the bonding state between a member constituting an adhesively joined structure and an adhesive layer.

[0012] The gist of the present invention completed based on this knowledge is as follows.

[0013] (1) An adhesively bonded structure comprising a first member, a second member, and an adhesive layer bonding the first member to the second member, wherein the first member is a plated steel member comprising a steel member and a plating layer on the steel member, the plating layer having a chemical composition comprising, in mass %, 0.50 to 5.00% Al, 0.50 to 3.00% Mg, and 0.01 to 15.00% Fe, and optionally further comprising one or more elements selected from the group consisting of the following element group A, element group B, element group C, element group D, element group E, element group F, and element group G; The balance is Zn and impurities. In the surface structure when looking down at the surface of the aforementioned coating, the average area ratio of the α precipitated η phase in the metallographic structure obtained by precipitation of the α phase in the η parent phase is 5 to 95%. When the cross-section of the aforementioned adhesive joint structure cut along the stacking direction of the aforementioned first component, the aforementioned second component and the aforementioned adhesive layer is observed using an electron microscope, the sum of the lengths of the contact between the aforementioned coating or the aforementioned steel component and the aforementioned adhesive layer, that is, the bonding length, is recorded as L, and the length of the observation field in the direction perpendicular to the surface normal direction of the aforementioned steel component is recorded as L0, the ratio L / L0 is greater than 1.10.

[0014] [Element Group A]: One or two elements selected from the group consisting of Si: more than 0% and 2.00% or less and Ca: more than 0% and 2.00% or less

[0015] [Element Group B]: One or more elements selected from the group consisting of Sb: more than 0% and 0.5000% or less, Pb: more than 0% and 0.50% or less, and Sr: more than 0% and 0.50% or less

[0016] [Element Group C]: One or more elements selected from the group consisting of Cu: more than 0% and 1.00% or less, Ti: more than 0% and 1.00% or less, Cr: more than 0% and 1.00% or less, Nb: more than 0% and 1.00% or less, Ni: more than 0% and 1.00% or less, Mn: more than 0% and 1.00% or less, Mo: more than 0% and 1.00% or less, Co: more than 0% and 1.0000% or less, and V: more than 0% and 1.0000% or less.

[0017] [Element Group D]: One or more elements selected from the group consisting of Sn: more than 0% and 1.00% or less, In: more than 0% and 1.0000% or less, and Bi: more than 0% and 1.0000% or less

[0018] [Element Group E]: One or more elements selected from the group consisting of Zr: more than 0% and 1.00% or less, Ag: more than 0% and 1.00% or less, and Li: more than 0% and 1.00% or less

[0019] [Element Group F]: One or more elements selected from the group consisting of La: more than 0% and 0.50% or less, Ce: more than 0% and 0.50% or less, and Y: more than 0% and 0.50% or less

[0020] [Element Group G]: B: more than 0% and 0.50% or less

[0021] (2) The adhesively bonded structure according to (1), which has a chemical composition containing the element group A.

[0022] (3) The adhesively bonded structure according to (1), which has a chemical composition containing the element group B.

[0023] (4) The adhesively bonded structure according to (1), which has a chemical composition containing the element group C.

[0024] (5) The adhesively bonded structure according to (1), which has a chemical composition containing the element group D.

[0025] (6) The adhesively bonded structure according to (1), which has a chemical composition containing the element group E.

[0026] (7) The adhesively bonded structure according to (1), which has a chemical composition containing the element group F.

[0027] (8) The adhesively bonded structure according to (1), which has a chemical composition containing the element group G.

[0028] (9) The adhesively bonded structure according to any one of (1) to (8), wherein the plating layer contains 1.00 to 5.00 mass% of Al and 1.00 to 3.00 mass% of Mg.

[0029] (10) An adhesively bonded structure according to any one of (1) to (8), wherein the first component further has a chemical conversion coating layer on the coating layer, and in the presence of the chemical conversion coating layer, the bonding length L is the sum of the lengths of contact between the chemical conversion coating layer, the coating layer or the steel component and the adhesive layer.

[0030] (11) The adhesively bonded structure according to (9), wherein the first component further has a chemical conversion coating layer on the coating layer, and in the presence of the chemical conversion coating layer, the bonding length L is the sum of the lengths of contact between the chemical conversion coating layer, the coating layer or the steel component and the adhesive layer.

[0031] (12) The adhesively bonded structure according to (10), wherein the chemical conversion coating layer contains at least one of: a carbamate group, an epoxy group, or an ester group; and a silicon compound having at least one of a Si-O bond and a Si-OH bond, and when the chemical conversion coating layer is subjected to Ar sputtering from the adhesive layer side toward the steel member side in a manner including any portion of the interface between the plating layer and the chemical conversion coating layer, a peak corresponding to a Si-O-Me bond is observed when the chemical conversion coating layer is analyzed by time-of-flight secondary ion mass spectrometry, wherein the Si-O-Me bond is a bond to a metal element Me (Me: F, Zn, Al, Mg) derived from the steel member or the plating layer, and the value obtained by dividing the count of the peak corresponding to the Si-O-Me bond by the total value of all secondary ion counts detected in the mass scan range of m / z = 0 to 300 is 1.0×10 -3 above.

[0032] (13) The adhesively bonded structure according to (11), wherein the chemical conversion coating layer contains at least one of: a carbamate group, an epoxy group, or an ester group; and a silicon compound having at least one of a Si-O bond and a Si-OH bond, and when the chemical conversion coating layer is subjected to Ar sputtering from the adhesive layer side toward the steel member side in a manner including any portion of the interface between the plating layer and the chemical conversion coating layer, a peak corresponding to a Si-O-Me bond is observed when analyzed by time-of-flight secondary ion mass spectrometry, wherein the Si-O-Me bond is a bond to a metal element Me (Me: F, Zn, Al, Mg) from the steel member or the plating layer, and the value obtained by dividing the count of the peak corresponding to the Si-O-Me bond by the total value of all secondary ion counts detected in the mass scan range of m / z = 0 to 300 is 1.0×10 -3 above.

[0033] (14) The adhesively bonded structure according to (1), wherein the steel member has a tensile strength of 980 MPa or more.

[0034] (15) The adhesively bonded structure according to (1), wherein the steel member has a tensile strength of 1180 MPa or more.

[0035] (16) The adhesively bonded structure according to (1), wherein the ratio L / L0 is 1.30 or more.

[0036] (17) The adhesively bonded structure according to (1), wherein the ratio L / L0 is 1.60 or more.

[0037] Effects of the Invention

[0038] As described above, according to the present invention, it is possible to provide an adhesively bonded structure that maintains red rust resistance and exhibits further excellent bonding durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is an explanatory diagram schematically showing an example of an adhesively bonded structure according to an embodiment of the present invention.

[0040] Figure 2A It is an explanatory diagram schematically showing an example of the structure of the adhesively bonded structure according to this embodiment.

[0041] Figure 2B It is an explanatory diagram schematically showing an example of the structure of the adhesively bonded structure according to this embodiment.

[0042] Figure 3 It is an explanatory diagram for explaining the plating layer included in the first member of the adhesively bonded structure according to this embodiment.

[0043] Figure 4 It is an explanatory diagram for explaining the plating layer included in the first member of the adhesively bonded structure according to this embodiment.

[0044] Figure 5 It is an explanatory diagram for explaining the bonding length of the adhesively bonded structure according to this embodiment. DETAILED DESCRIPTION

[0045] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in this specification and the accompanying drawings, components having substantially the same functional configuration are denoted by the same reference numerals to omit repeated description.

[0046] (Regarding adhesively bonded structures)

[0047] <About the Overall Structure of the Adhesive Bonded Structure>

[0048] First, refer to Figure 1 The overall structure of the adhesively bonded structure according to the embodiment of the present invention will be described. Figure 1 It is an explanatory diagram schematically showing an example of the adhesively bonded structure according to the present embodiment.

[0049] like Figure 1 As shown schematically, the adhesively bonded structure 1 of this embodiment includes a first member 10 and a second member 20. Figure 1 , an example in which a so-called hat-shaped metal member is used as an example of the first member 10 is shown. Figure 1The first member 10 shown has a web portion, a pair of longitudinal walls connected to both widthwise edges of the web portion, and a pair of flanges connected to these longitudinal walls. It is a metal member having a hat-shaped cross-section perpendicular to the longitudinal direction (the depth of the paper). The web portion has a rectangular shape that is long in one direction.

[0050] exist Figure 1 In the embodiment, the second member 20 is bonded to the first member 10 via the adhesive layer 30 in the bonding region inside the web portion of the first member 10. Here, the inside of the web portion refers to the region surrounded by the web portion and the vertical wall portion.

[0051] It should be noted that, although the following description uses the case where the first member 10 is a hat-shaped member as an example, in this embodiment, the various members constituting the adhesively bonded structure 1 are not limited to the shapes shown in the figure. Furthermore, in this embodiment, at least the first member 10 may be a galvanized steel member having a specific coating layer as described in detail below, and the blank of the second member 20 is not particularly limited.

[0052] The following describes in detail the various components of the adhesively bonded structure 1 in the bonding region where the first member 10 and the second member 20 are bonded via the adhesive layer 30, with reference to Figure 2. Figure 2 is an explanatory diagram schematically showing an example of the structure of the bonding region of the adhesively bonded structure 1 according to this embodiment.

[0053] <About the First Member 10>

[0054] Next, refer to Figure 2A and Figure 2B Next, the first member 10 included in the adhesively bonded structure 1 of the present embodiment will be described. Figure 2A and Figure 2B It is an explanatory diagram schematically showing an example of the structure of the adhesively bonded structure according to the present embodiment.

[0055] In the adhesively bonded structure 1 of this embodiment, as the raw material of at least the first member 10 in the adhesive region, as mentioned above, a galvanized steel member having a specific coating layer is used. Here, the steel member refers to a steel product obtained by processing a steel plate and used in the fields of automobiles, home appliances, and building materials. The first member 10 in the adhesive region can be as follows: Figure 2A The schematic diagram shows a steel member 101 as a base material of a galvanized steel member and a coating 103 on the steel member 101. Figure 2B Schematically shown are a steel member 101 as a base material of a galvanized steel member, a plating layer 103 on the steel member 101 , and a chemical conversion coating layer 105 on the plating layer 103 .

[0056] Hereinafter, the first member 10 of this embodiment is as follows Figure 2B The case where a steel member 101, a plating layer 103, and a chemical conversion coating layer 105 are shown will be described as an example.

[0057] About Steel Structures 101

[0058] The size, composition, structure, and mechanical properties of the steel member 101 serving as the parent material of the first member 10 are not particularly limited. For example, various steel members can be used depending on the mechanical strength (e.g., tensile strength) required of the adhesively bonded structure 1. Examples of such steel members 101 include steel materials specified in the Japanese Industrial Standards (JIS), such as carbon steel, alloy steel, and high-tensile steel used for general structural and / or mechanical structural purposes. Specific examples of such steel materials include cold-rolled steel, hot-rolled steel, hot-rolled steel sheets for automotive structures, hot-rolled high-tensile steel sheets for automotive processing, cold-rolled steel sheets for automotive structures, cold-rolled high-tensile steel sheets for automotive processing, and high-tensile steel materials commonly referred to as hot stamping materials that are quenched during hot working. The composition of such steel materials is not particularly limited, and in addition to Fe and C, they may also contain one or more of Si, Mn, S, P, Al, N, Cr, Mo, Ni, Cu, Ca, Mg, Ce, Hf, La, Zr, and Sb. In order to obtain the required material strength and formability, one or more of these optional added elements may be appropriately selected, and the content may be appropriately adjusted.

[0059] Among the high-strength steels described above, for example, by using high-strength steel having a tensile strength of 980 MPa or more (so-called high-strength steel of the 980 MPa grade or more) and / or high-strength steel having a tensile strength of 1180 MPa or more (so-called high-strength steel of the 1180 MPa grade or more), the robustness of the manufactured article can be further improved, and therefore it is more preferable. Here, the tensile strength of the steel member 101 can be measured by a known method. As an example, for the adhesive joint structure whose tensile strength is to be measured, a chisel is inserted into the position of the adhesive layer to destroy the adhesive layer. Then, a coating stripper is used to remove the chemical conversion coating layer and the adhesive layer remaining on the first member. Next, the remaining plating layer is immersed in a 10% HCl aqueous solution to which an inhibitor has been added for about 1 minute, and the plating layer is partially peeled off, thereby obtaining a sample of the steel member 101. A test piece specified in JIS Z 2241:2011 is prepared from a part of the above sample, and the tensile strength of the obtained test piece is measured using the specified method. If it is not possible to obtain a sample of the steel member 101 from the portion where the adhesive layer is present, a test piece specified in JIS Z 2241:2011 can be prepared from a flat portion continuous with the steel member 101 and without the adhesive layer, and the tensile strength can be measured. The tensile strength obtained in this manner is considered the tensile strength of the steel member 101 present in the portion where the adhesive layer is present. It should be noted that the tensile strength of the steel material does not significantly change even if a plating layer is present. Therefore, even if a plating layer is present on the test piece obtained as described above, the measured tensile strength can be considered the tensile strength of the steel member 101.

[0060] The thickness of the steel member 101 is not particularly limited and may be appropriately set according to the mechanical strength required of the first member 10 .

[0061] About Coating 103

[0062] like Figure 2B As schematically shown, the plating layer 103 is provided on the surface of the steel member 101 in the bonding region, but is more preferably provided on the entire surface of the steel member 101. First, the chemical composition of the plating layer 103 will be described in detail below.

[0063] ◇About the chemical composition of coating 103

[0064] According to one embodiment, the chemical composition of the plating layer 103 of the present embodiment has the following chemical composition: Al: 0.50-5.00%, Mg: 0.50-3.00%, Fe: 0.01-15.00%, and the balance Zn and impurities.

[0065] According to another embodiment, the chemical composition of the plating layer 103 of this embodiment has the following composition: Al: 0.50-5.00%, Mg: 0.50-3.00%, Fe: 0.01-15.00%, and one or more elements selected from the group consisting of the following element groups: A, B, C, D, E, F, and G, with the balance being Zn and impurities. Specifically, in the chemical composition of the plating layer 103 of this embodiment, the contents of Al, Mg, and Fe are within the above-described ranges, the total content of Al, Mg, Fe, and elements A through G is less than 100% by mass, and the balance is Zn and impurities.

[0066] [Element Group A]: One or two elements selected from the group consisting of Si: more than 0% and 2.00% or less and Ca: more than 0% and 2.00% or less

[0067] [Element Group B]: One or more elements selected from the group consisting of Sb: more than 0% and 0.5000% or less, Pb: more than 0% and 0.5000% or less, and Sr: more than 0% and 0.5000% or less

[0068] [Element Group C]: One or more elements selected from the group consisting of Cu: more than 0% and 1.0000%, Ti: more than 0% and 1.0000%, Cr: more than 0% and 1.0000%, Nb: more than 0% and 1.0000%, Ni: more than 0% and 1.0000%, Mn: more than 0% and 1.0000%, Mo: more than 0% and 1.0000%, Co: more than 0% and 1.0000%, and V: more than 0% and 1.0000%.

[0069] [Element Group D]: One or more elements selected from the group consisting of Sn: more than 0% and 1.0000% or less, In: more than 0% and 1.0000% or less, and Bi: more than 0% and 1.0000% or less

[0070] [Element Group E]: One or more elements selected from the group consisting of Zr: more than 0% and 1.0000% or less, Ag: more than 0% and 1.0000% or less, and Li: more than 0% and 1.0000% or less

[0071] [Element Group F]: one or more elements selected from the group consisting of La: more than 0% and 0.5000% or less, Ce: more than 0% and 0.5000% or less, and Y: more than 0% and 0.5000% or less

[0072] [Element Group G]: B: more than 0% and 0.5000% or less

[0073] Thus, the coating 103 of this embodiment is a coating having the following chemical composition: in terms of mass %, it contains Al: 0.50-5.00%, Mg: 0.50-3.00%, Fe: 0.01-15.00%, and selectively contains one or more selected from the group consisting of element group A, element group B, element group C, element group D, element group E, element group F and element group G, with the remainder being Zn and impurities.

[0074] [Al: 0.50-5.00 mass %]

[0075] Al is an element necessary for constituting the main phase (Zn-Al-Mg alloy phase) of the coating 103 of the present embodiment. In order to ensure the corrosion resistance as a plated steel component, it is necessary to contain a certain amount or more. When the Al content in the coating 103 is less than 0.50% by mass, the corrosion resistance as a plated steel component cannot be ensured. Therefore, in the coating 103 of the present embodiment, the Al content is 0.50% by mass or more. The Al content is preferably 1.00% by mass or more, more preferably 1.00% by mass or more. By making the Al content within the above range, the corrosion resistance as a plated steel component can be ensured.

[0076] On the other hand, when the Al content in the coating 103 exceeds 5.00% by mass, the solidification behavior of the coating from the liquid phase to the solid phase changes, making it difficult to crystallize the η phase, and forming a dendritic structure mainly composed of Al. If a dendritic structure mainly composed of Al is formed, it will promote corrosion in the surrounding area, and therefore the corrosion resistance of the plated steel component cannot be ensured. In addition, due to the lack of η phase, the interface between the η phase and the eutectic structure, which is the source of cracks, is reduced, which also becomes the cause of insufficient cracks generated during processing. Therefore, in the coating 103 of the present embodiment, the Al content is 5.00% by mass or less. The Al content is preferably 4.00% by mass or less, and more preferably 3.00% by mass or less.

[0077] [Mg: 0.50-3.00 mass %]

[0078] Mg is an element necessary for constituting the main phase (Zn-Al-Mg alloy phase) of the coating 103 of the present embodiment, and in order to ensure the corrosion resistance as a plated steel component, it is necessary to contain a certain amount or more. Therefore, in the coating 103 of the present embodiment, the Mg content is 0.50% by mass or more. The Mg content is preferably 1.50% by mass or more, and more preferably 2.00% by mass or more. By making the Mg content within the above range, the corrosion resistance as a plated steel component can be ensured. When the Mg content exceeds 3.00%, it is difficult to precipitate the α phase from the η phase. The η phase in which Al is dissolved is hard, so deformation cannot be concentrated on the η phase during processing, which is the reason for the reduction in the number of cracks. Therefore, the upper limit of the Mg content is 3.00%.

[0079] On the other hand, when the Mg content in the coating 103 is less than 0.50 mass%, the corrosion resistance improvement effect brought about by the modification of corrosion products is insufficient, and therefore the corrosion resistance of the plated steel component cannot be ensured. Furthermore, if the Mg content is insufficient, the entire coating 103 softens, and deformation cannot be concentrated in the η phase during processing, which causes a decrease in the number of cracks. Therefore, in the coating 103 of this embodiment, the Mg content is 0.50 mass% or more. The Mg content is preferably 1.50 mass% or more, and more preferably 2.00 mass% or more. By setting the Mg content within the above range, the corrosion resistance of the plated steel component can be ensured.

[0080] [Fe: 0.01 to 15.00 mass%]

[0081] Elements that constitute the steel member may sometimes be incorporated into the coating 103 from the steel member 101, which serves as the base material. In particular, during hot-dip coating, elements that constitute the steel member 101 are easily incorporated into the coating 103 due to interdiffusion of elements caused by a solid-liquid reaction between the steel member 101 and the coating 103. This incorporation of elements results in a certain amount of Fe being incorporated into the coating 103, typically at a content of 0.01% by mass or greater. Promoting this interdiffusion improves the adhesion between the steel member 101 and the coating 103. To enhance the adhesion between the steel member 101 and the coating 103, the Fe content in the coating 103 is preferably at least 0.20% by mass.

[0082] Furthermore, Fe may be intentionally added to the plating bath used to produce the coating 103, within a range that does not impair the effects of the present invention. However, if the Fe content in the coating 103 is 15.00 mass % or greater, a high-melting-point intermetallic compound of Fe and Al is formed in the coating bath. This high-melting-point intermetallic compound adheres to the coating as scum, significantly reducing the appearance quality, which is not preferable. From this perspective, the Fe content in the coating bath is adjusted to 15.00 mass % or less. The Fe content in the coating 103 is more preferably 10.00 mass % or less.

[0083] In the plating layer 103 , the balance of the above-mentioned Al, Mg, and Fe is Zn and impurities.

[0084] Zn is an element necessary for constituting the main phase (Zn—Al—Mg alloy phase) of the plating layer 103 of the present embodiment, and is an important element for improving the corrosion resistance of the plated steel member.

[0085] Next, element groups A to E that may be included in the chemical composition of the plating layer 103 according to another aspect of the present embodiment will be described in detail.

[0086] It should be noted that in the coating 103 of this embodiment, when containing at least one element belonging to the following element group B to element group E, it is preferred that the coating 103 contain at least one element belonging to the following element group B to element group E within the following content range and with a total content of 5.0000 mass % or less.

[0087] By setting the total content of elements belonging to element groups B to E to 5.0000 mass % or less, the effects exhibited by the addition of each element, as described in detail below, can be achieved without mutually impairing each other. The total content of elements belonging to element groups B to E is preferably 1.0000 mass % or less, and more preferably 0.2000 mass % or less.

[0088] ◇Element Group A

[0089] In another aspect of the plating layer 103 of this embodiment, the element group A that can be contained in the plating layer 103 will be described. At least one element of the element group A described below is an element that can be contained in the plating layer 103 in place of a portion of the balance Zn.

[0090] [Element Group A]: One or two elements selected from the group consisting of Si: more than 0% and 2.00% or less and Ca: more than 0% and 2.00% or less

[0091] [Si: 0-2.00 mass %]

[0092] The coating 103 of this embodiment may not contain Si, so the lower limit of the Si content is 0% by mass. On the other hand, Si is an element that can suppress the excessive growth of Fe-Al intermetallic compounds formed at the interface between the coating and the steel member, thereby further improving the adhesion between the coating 103 and the steel member 101. When Si is contained in the coating 103, in order to suppress the excessive growth of Fe-Al intermetallic compounds, the Si content is preferably 0.05% by mass or more, and more preferably 0.10% by mass or more.

[0093] On the other hand, when the Si content exceeds 2.00% by mass, Si and Mg excessively form a high-melting-point intermetallic compound. In this embodiment, the first component 10 is sometimes joined to the second component 20 by a second joining method such as welding in addition to the adhesive layer 30. However, if this high-melting-point intermetallic compound of Si and Mg is excessively formed, it is possible to hinder the formation of Al-Mg oxides that exhibit a Zn evaporation-inhibiting effect when welding the portion where the coating is present. Therefore, the Si content in the coating 103 is preferably 2.00% by mass. In addition, if the Si content in the plating bath used to manufacture the coating 103 is too high, the viscosity of the coating bath may increase beyond necessity, resulting in a decrease in plating workability. Therefore, from the perspective of plating workability, by adjusting the Si content in the coating bath, the Si content in the coating 103 is preferably 1.00% by mass or less, and more preferably 0.50% by mass or less.

[0094] [Ca: 0-2.00 mass %]

[0095] The coating 103 of this embodiment may not contain Ca, so the lower limit of the Ca content is 0% by mass. On the other hand, if Ca is contained in the coating 103, it forms intermetallic compounds with Al and Zn. Furthermore, if Si is contained in the coating 103 along with Ca, Ca and Si form intermetallic compounds. These intermetallic compounds have high melting points and stable structures, and therefore, when welding is used as the second joining method, liquid metal embrittlement cracking (LME) during welding can be suppressed. When Ca is contained in the coating 103, the effect of suppressing LME during welding is achieved by setting the Ca content to 0.01% by mass or more. The Ca content in the coating 103 is more preferably 0.05% by mass or more.

[0096] On the other hand, if the Ca content in the coating 103 exceeds 2.00 mass%, the corrosion resistance of the plated steel member may be reduced. From this viewpoint, the Ca content in the coating 103 is 2.00 mass% or less. The Ca content in the coating 103 is preferably 1.50 mass% or less, and more preferably 1.00 mass% or less.

[0097] ◇Element Group B

[0098] Next, in another aspect of the plating layer 103 of this embodiment, the element group B that can be contained in the plating layer 103 will be described. At least one element of the element group B described below is an element that can be contained in the plating layer 103 in place of a portion of the balance Zn.

[0099] [Element Group B]: One or more elements selected from the group consisting of Sb: more than 0% and 0.5000% or less, Pb: more than 0% and 0.5000% or less, and Sr: more than 0% and 0.5000% or less

[0100] [Sb: 0 to 0.5000 mass %]

[0101] [Pb: 0 to 0.5000 mass %]

[0102] [Sr: 0 to 0.5000 mass %]

[0103] It is also possible to consider the case where the coating 103 of the present embodiment does not contain Sb, Pb, or Sr, so the lower limit of the content of these elements is 0% by mass. On the other hand, if at least any one of Sb, Pb, and Sr is contained in the coating 103, zinc flowers are formed on the surface of the coating 103, and it is possible to achieve an improvement in metallic luster. Therefore, from the viewpoint of improving the designability of the plated steel component, it is preferred that at least any one of Sb, Pb, and Sr is contained in the coating 103. This designability improvement effect is manifested when the content of at least any one of Sb, Pb, and Sr is 0.0500% by mass or more. Therefore, when at least any one of Sb, Pb, and Sr is contained in the coating 103, the content of these elements is each independently preferably 0.0500% by mass or more.

[0104] On the other hand, when forming the coating 103 in which any one of the contents of Sb, Pb, and Sr exceeds 0.5000 mass%, the amount of scum generated in the coating bath used to form the coating 103 increases, and it is impossible to produce a plated steel sheet with good coating properties. Therefore, the contents of Sb, Pb, and Sr in the coating 103 are each independently 0.5000 mass% or less. The contents of Sb, Pb, and Sr are each independently preferably 0.2000 mass% or less.

[0105] ◇Element Group C

[0106] Next, in another aspect of the plating layer 103 of this embodiment, the element group C that can be contained in the plating layer 103 will be described. At least one element of the element group C described below is an element that can be contained in the plating layer 103 in place of a portion of the balance Zn.

[0107] [Element Group C]: One or more elements selected from the group consisting of Cu: more than 0% and 1.0000%, Ti: more than 0% and 1.0000%, Cr: more than 0% and 1.0000%, Nb: more than 0% and 1.0000%, Ni: more than 0% and 1.0000%, Mn: more than 0% and 1.0000%, Mo: more than 0% and 1.0000%, Co: more than 0% and 1.0000%, and V: more than 0% and 1.0000%.

[0108] [Cu: 0 to 1.0000 mass %]

[0109] [Ti: 0 to 1.0000 mass%]

[0110] [Cr: 0 to 1.0000 mass %]

[0111] [Nb: 0 to 1.0000 mass%]

[0112] [Ni: 0 to 1.0000 mass %]

[0113] [Mn: 0 to 1.0000 mass %]

[0114] [Co: 0 to 1.0000 mass %]

[0115] [V: 0 to 1.0000 mass %]

[0116] The coating 103 of this embodiment may not contain Cu, Ti, Cr, Nb, Ni, Mn, Co, or V. Therefore, the lower limit of the content of these elements is 0% by mass. On the other hand, if at least one of Cu, Ti, Cr, Nb, Ni, Mn, Co, and V is contained in the coating 103, then when welding is used as the second joining method, these elements will be incorporated into the Fe-Al intermetallic compound formed by welding, thereby improving the corrosion resistance of the resulting weld. This effect of improving the corrosion resistance of the weld is achieved when the content of at least one of Cu, Ti, Cr, Nb, Ni, Mn, Co, and V in the coating 103 is 0.0050% by mass or more. Therefore, when at least one of Cu, Ti, Cr, Nb, Ni, Mn, Co, and V is contained in the coating 103, the content of each of these elements independently is preferably 0.0050% by mass or more.

[0117] On the other hand, when forming the coating 103 in which the content of any of Cu, Ti, Cr, Nb, Ni, Mn, Co, and V exceeds 1.0000 mass%, these elements form various intermetallic compounds in the plating bath used to form the coating 103, causing the viscosity of the plating bath to increase, and it is impossible to produce a plated steel component with good plating properties. Therefore, the content of Cu, Ti, Cr, Nb, Ni, Mn, Co, and V in the coating 103 is each independently 1.0000 mass% or less. The content of Cu, Ti, Cr, Nb, Ni, Mn, Co, and V is each independently 0.2000 mass% or less.

[0118] [Mo: 0 to 1.0000 mass %]

[0119] The coating 103 of this embodiment may not contain Mo, so the lower limit of the Mo content is 0 mass%. On the other hand, if Mo is included in the coating 103, the corrosion resistance can be further improved. This corrosion resistance improvement effect is apparent when the Mo content is 0.0100 mass% or more. Therefore, when Mo is included, its content is preferably 0.0100 mass% or more.

[0120] On the other hand, if the plating layer 103 is formed with a Mo content exceeding 1.0000 mass%, this will cause a large amount of scum to be generated in the plating bath used, which is not preferable. Therefore, the Mo content is 1.0000 mass% or less. The Mo content is preferably 0.0500 mass% or less.

[0121] ◇Element Group D

[0122] Next, in another aspect of the plating layer 103 of the present embodiment, the element group D that can be contained in the plating layer 103 will be described. The elements of the element group D described below are elements that can be contained in the plating layer 103 in place of a portion of the balance Zn.

[0123] [Element Group D]: One or more elements selected from the group consisting of Sn: more than 0% and 1.0000% or less, In: more than 0% and 1.0000% or less, and Bi: more than 0% and 1.0000% or less

[0124] [Sn: 0 to 1.0000 mass %]

[0125] [In: 0 to 1.0000 mass %]

[0126] [Bi: 0 to 1.0000 mass %]

[0127] It is also possible to consider the case where the coating 103 of this embodiment does not contain Sn, In, or Bi, so the lower limit of the content of Sn, In, and Bi is 0% by mass. On the other hand, the coating 103 containing Sn, In, and Bi is an element that increases the Mg dissolution rate when placed in a corrosive environment. If the Mg dissolution rate increases, Mg ions are supplied to the exposed portion of the steel member 101, improving corrosion resistance. From this viewpoint, when containing Sn, In, and Bi, it is preferred that the content of Sn, In, and Bi be each independently set to 0.0050% by mass or more. On the other hand, adding excessive amounts of Sn, In, and Bi will excessively promote the Mg dissolution rate, potentially reducing the corrosion resistance of the plated steel member. If any of the contents of Sn, In, and Bi exceeds 1.0000% by mass, the increase in the Mg dissolution rate becomes significant, so the contents of Sn, In, and Bi are each independently 1.0000% by mass or less. The contents of Sn, In, and Bi are each independently preferably 0.2000% by mass or less.

[0128] ◇Element Group E

[0129] Next, in another aspect of the plating layer 103 of this embodiment, the element group E that can be contained in the plating layer 103 will be described. At least one element of the element group E described below is an element that can be contained in the plating layer 103 in place of a portion of the balance Zn.

[0130] [Element Group E]: One or more elements selected from the group consisting of Zr: more than 0% and 1.0000% or less, Ag: more than 0% and 1.0000% or less, and Li: more than 0% and 1.0000% or less

[0131] [Zr: 0 to 1.0000 mass %]

[0132] [Ag: 0 to 1.0000 mass %]

[0133] [Li: 0 to 1.0000 mass %]

[0134] It is also possible to consider the case where the plating layer 103 of the present embodiment does not contain Zr, Ag, and Li, so the lower limit of the content of these elements is 0% by mass. On the other hand, if at least any one of Zr, Ag, and Li is contained in the plating layer 103, the plating workability can be improved. The effect of improving the plating property is manifested when the content of at least any one of Zr, Ag, and Li in the plating layer 103 becomes 0.0100% by mass or more. Therefore, when containing at least any one of Zr, Ag, and Li, the content of these elements is preferably 0.0100% by mass or more, each independently.

[0135] On the other hand, when forming the plating layer 103 in which the content of any one of Zr, Ag, and Li exceeds 1.0000 mass%, a large amount of scum is likely to be generated in the plating bath used to form the plating layer 103. Therefore, the content of at least one of Zr, Ag, and Li is each independently 1.0000 mass% or less. The content of at least one of Zr, Ag, and Li is each independently preferably 0.1000 mass% or less.

[0136] ◇Element Group F

[0137] Next, in another aspect of the plating layer 103 of this embodiment, the element group F that can be contained in the plating layer 103 will be described. At least one element of the element group F described below is an element that can be contained in the plating layer 103 in place of a portion of the balance Zn.

[0138] [Element Group F]: one or more elements selected from the group consisting of La: more than 0% and 0.5000% or less, Ce: more than 0% and 0.5000% or less, and Y: more than 0% and 0.5000% or less

[0139] [La: 0 to 0.5000 mass %]

[0140] [Ce: 0 to 0.5000 mass %]

[0141] [Y: 0 to 0.5000 mass %]

[0142] It is also possible to consider the case where the coating 103 of this embodiment does not contain La, Ce, and Y. Therefore, the lower limit of the content of these elements is 0% by mass. On the other hand, La, Ce, and Y are elements that show an effect roughly equivalent to that of Ca. This is because the atomic radius of each element is close to that of Ca. If these elements are contained in the coating 103, they will be substituted at the Ca position.

[0143] This effect is achieved by setting the content of each of these elements independently to 0.0100 mass% or greater. Therefore, when at least one of Zr, Ag, and Li is contained, the content of each of these elements is preferably independently 0.0100 mass% or greater. The content of La, Ce, and Y in the plating layer 103 is more preferably independently 0.0500 mass% or greater.

[0144] On the other hand, if the La, Ce, and Y contents in the plating bath used to produce the coating layer 103 are excessive, the viscosity of the plating bath may increase beyond necessity, thereby reducing plating workability. Therefore, from the perspective of plating workability, the La, Ce, and Y contents in the plating bath are adjusted so that the La, Ce, and Y contents are each independently 0.5000 mass % or less. The La, Ce, and Y contents are each preferably 0.1000 mass % or less.

[0145] ◇Element Group G

[0146] Next, in another aspect of the plating layer 103 of the present embodiment, the element group G that can be contained in the plating layer 103 will be described. The elements of the element group G shown below are elements that can be contained in the plating layer 103 in place of a portion of the balance Zn.

[0147] [Element Group G]: B: more than 0% and 0.5000% or less

[0148] [B: 0 to 0.5000 mass %]

[0149] It is also conceivable that the coating 103 of this embodiment does not contain B, so the lower limit of its content is 0 mass%. On the other hand, if B is contained in the coating 103, it has the effect of suppressing LME when welding is used as the second welding method. This is presumably because the presence of B in the coating 103 combines with at least one of Zn, Al, Mg, and Ca to form various intermetallic compounds. Furthermore, it is believed that the presence of B in the coating 103 allows B to diffuse from the coating 103 into the steel member 101, suppressing LME in the steel member 101 through grain boundary strengthening. Furthermore, it is presumed that the melting points of the various intermetallic compounds formed by B are extremely high, thus also contributing to the suppression of Zn evaporation during welding. These improvements are achieved when B is contained in an amount of 0.0500 mass% or more. Therefore, when B is contained, the B content is preferably 0.0500 mass% or more.

[0150] On the other hand, if the coating bath contains excessive amounts of B in order to include B in the coating layer 103, the coating melting point will rise sharply, the coating workability will decrease, and it will be impossible to produce a coated steel sheet with excellent coating properties. This decrease in coating workability becomes significant when the B content exceeds 0.50% by mass, so the B content is 0.5000% by mass or less. The B content is preferably 0.1000% by mass or less.

[0151] [Measurement method of chemical composition]

[0152] The chemical composition of the above-mentioned coating 103 can be measured using inductively coupled plasma atomic emission spectroscopy (ICP-AES, Inductively Coupled Plasma Atomic Emission Spectrometry) or inductively coupled plasma mass spectrometry (ICP-MS, Inductively Coupled Plasma Mass Spectrometry). It should be noted that, when analyzing chemical components up to 0.1% by mass, ICP-AES is used, and when analyzing trace chemical components less than 0.1% by mass, ICP-MS is used. The sample collected from the adhesive bonding structure of interest as described below is immersed in a 10% HCl aqueous solution to which an inhibitor is added for about 1 minute, the coating portion is peeled off, and a solution in which the coating is dissolved is prepared. The obtained solution is analyzed by ICP-AES or ICP-MS to obtain the overall average chemical composition of the coating.

[0153] Here, in the adhesively bonded structure of interest, when sampling the plating layer, the following procedure may be performed.

[0154] First, in an adhesively bonded structure, a chisel is inserted into the adhesive layer between the first and second components to break the adhesive layer. Then, a coating stripper is used to remove the chemical conversion coating layer and adhesive layer remaining on the first component. This provides a sample for chemical composition analysis.

[0155] If it is not possible to obtain a sample of the first member from the portion where the adhesive layer is present, a sample of the first member may be taken from the same surface on the side where the adhesive layer is present and analyzed as described above. The analysis results obtained in this manner shall be regarded as the analysis results of the plating layer present in the portion where the adhesive layer is present.

[0156] ◇About the adhesion amount of plating layer 103

[0157] There is no particular limitation on the amount of coating 103 applied. For example, it is preferably 15 to 250 g / m² per surface of the steel member. 2 By setting the coating amount of the plating layer 103 within the above-mentioned range, the plated steel member of the present embodiment can exhibit sufficient corrosion resistance.

[0158] The adhesion amount of the coating 103 is measured as follows. First, in the same manner as described above, a sample having a size of 30 mm × 30 mm when viewed from above is cut out from the adhesively bonded structure of interest. It should be noted that when cutting out the sample, the entire thickness direction is cut out, and the chemical conversion treatment coating layer and the adhesive layer are removed in advance using a coating stripper. On this basis, the mass of the sample collected in this way is measured in advance. A sealing tape is affixed to one surface of the sample so that the coating on this side does not dissolve in the next process. On this basis, the sample is immersed in a 10% HCl aqueous solution to which an inhibitor is added, the coating is pickled and stripped, and the mass of the sample after pickling is measured. Based on the change in the mass of the sample before and after pickling, the adhesion amount of the coating 103 on each side can be determined.

[0159] It should be noted that if a sample of the first member cannot be obtained from the portion where the adhesive layer is present, a sample of the first member can be taken from a flat portion that is continuous with the steel member 101 and does not have an adhesive layer, and the above-described measurement can be performed. The measurement results of the adhesion amount obtained in this manner are regarded as the measurement results of the plating layer present in the portion where the adhesive layer is present.

[0160] ◇About the metallographic structure of coating 103

[0161] Next, the metallographic structure of the plating layer 103 having the chemical composition described above will be described.

[0162] The coating 103 of the present embodiment has the above-mentioned chemical composition. In addition, the coating 103 is formed by the manufacturing method described in detail below, and contains metal phases and / or intermetallic compound phases such as α phase, η-Zn phase, MgZn2 phase, η / α / MgZn2 ternary eutectic phase, η / MgZn2 binary eutectic phase. In addition, depending on the elements that the coating 103 may also contain, in addition to the phases described above, the coating 103 may also contain intermetallic compound phases such as Al-Si-Ca phase, Al-Si-Ca-Fe phase, Mg2Si phase, Mg2Sn phase. The coating 103 of the present embodiment shows excellent corrosion resistance by having the metallographic structure described above. In addition, in the coating 103 of the present embodiment, a portion of the above-mentioned α phase and η-Zn phase exists in a specific state as described in detail below.

[0163] Here, what kind of metallographic structure the plating layer 103 of this embodiment has can be determined by observing the surface of the plating layer 103 using a scanning electron microscope (SEM).

[0164] In this observation, a sample is first collected from the adhesively bonded structure of interest, as described above, and the surface of the coating 103 is exposed using a coating stripper. The solidified structure of the coating 103 surface is then observed using an SEM. The phases present in the observation field can be determined based on the point analysis results of SEM-EPMA (Electron Probe Micro Analyzer) and the morphology of the crystalline phases in the reflected electron image. In this case, pre-processing such as polishing before SEM observation is not necessary.

[0165] Next, refer to Figure 3 and Figure 4 The specific state in which a portion of the α phase and the η-Zn phase are present in the plating layer 103 of this embodiment will be described in detail. Figure 3 and Figure 4 This is a schematic diagram for explaining the α-precipitated η phase included in the plating layer 103 of the present embodiment.

[0166] Focus is placed on the observation of the surface of the plating layer 103 according to this embodiment from the surface normal direction using an electron microscope (SEM).

[0167] When this observation was performed, in the plating layer 103 of the present embodiment, its surface structure had the α-precipitated η phase ( Figure 3 The α-precipitated η phase 111 has an average area ratio of 5 to 95%. Furthermore, the remainder of the α-precipitated η phase 111 forms a hard structure 113 composed of a MgZn2 phase, an η / α / MgZn2 ternary eutectic phase, an η / MgZn2 binary eutectic phase, and the like. It should be noted that the coating 103 of this embodiment contains 0.50% by mass or more of Mg as a chemical composition of the coating, and therefore, the hard structure 113 described above is inevitably formed by this chemical composition.

[0168] like Figure 4 As schematically shown, the α-precipitated η phase 111 is a metallurgical structure in which Al supersaturated solid solution in a matrix phase composed of an η-Zn phase (hereinafter referred to as "η matrix phase 123") precipitates as α phase 121, resulting in softening. When focusing on the backscattered electron image during SEM observation, the α phase 121 appears as a black substance, while the η matrix phase 123 appears as a white substance. Therefore, when observing the α-precipitated η phase 111 using a backscattered electron image, it is recognized as a structure consisting of black particles dispersed within a white phase.

[0169] The presence of such α-precipitated η phase 111 in the hard structure 113 causes uneven hardness in the plating layer 103. When a relatively soft metallographic structure exists within the hard metallographic structure, and strain is applied to the plating layer 103 due to processing for processing the plated steel member into a desired shape and / or pressure welding during the production of an adhesively bonded structure, the applied strain is concentrated on the α-precipitated η phase 111, which is the soft metallographic structure.

[0170] Furthermore, in the surface structure of the coating 103 of this embodiment, as described above, the average area ratio of the α-precipitated η phase 111 is within the range of 5 to 95%. By setting the average area ratio of the α-precipitated η phase 111 within the above range, even when the above-described strain is applied, the strain is not excessively concentrated in the α-precipitated η phase 111, and the desired bonding durability can be achieved.

[0171] If the average area ratio is less than 5%, the amount of α-precipitated η phase 111 present is too small, and the desired bonding durability cannot be achieved. By setting the average area ratio to 5% or higher, the desired bonding durability can be improved while maintaining corrosion resistance. The average area ratio of α-precipitated η phase 111 is preferably 8% or higher, and more preferably 15% or higher.

[0172] On the other hand, if the average area ratio of the α-precipitated η phase 111 exceeds 95%, the soft α-precipitated η phase occupies the majority of the coating, causing the coating as a whole to exhibit ductility, making it difficult to achieve the adhesion durability described below. This is not preferred. By setting the average area ratio of the α-precipitated η phase 111 to 95% or less, it is possible to maintain corrosion resistance while achieving the adhesion durability described below. The average area ratio of the α-precipitated η phase 111 is preferably 70% or less, more preferably 40% or less, and even more preferably 30% or less.

[0173] In addition, the effect of improving the bonding durability by the α-precipitated η phase 111 will be described again in detail below.

[0174] ◇Calculation method of the average area ratio of the α-precipitated η phase 111 in the coating layer 103

[0175] Here, the above-mentioned average area ratio is measured as follows.

[0176] Specifically, an elemental map is obtained by observing an arbitrary position on the surface of the coating 103 using SEM-EPMA. The obtained elemental map is binarized using the binarization function of a commercially available image analysis application, and the region corresponding to the α-precipitated η phase 111 is determined, and its area ratio is calculated.

[0177] More specifically, in the sample obtained as described above, an area of ​​120 μm×100 μm in plan view at an arbitrary position on the surface of the plating layer 103 was observed by SEM (equivalent to approximately 1000-fold magnification), and point analysis was performed by SEM-EPMA.

[0178] Specifically, the acceleration voltage was 15.0 kV, the irradiation current was 4.999×10 -8 A. Irradiation time: 50 milliseconds. Observe the aforementioned 120 μm × 100 μm area at a magnification of 1000. Under these conditions, obtain a reflected electron image of the desired area and, using the contrast of the reflected electron image, perform point analysis on three points for each metallographic structure.

[0179] In this analysis, a phase that satisfies the following conditions: Al: 20-99 atomic %, Zn: 0.5-80 atomic %, Mg: 0-5 atomic %, and a total of Al and Zn content of 70 atomic % or greater can be identified as an α phase. Furthermore, a phase with a Zn content of 98 atomic % or greater and a total content of other elements of 2 atomic % or less can be identified as an η-Zn phase.

[0180] It should be noted that the phase in which the content of Mg and Zn is respectively greater than 10 atomic % and the total content of Mg and Zn is greater than 85 atomic % is judged to be a hard structure 113 composed of MgZn2 phase, η / α / MgZn2 ternary eutectic phase, η / MgZn2 binary eutectic phase, etc.

[0181] The η-Zn phase contains no Mg, while a hard structure 113 containing Mg exists around the η-Zn phase. Therefore, by focusing on the distribution of the Mg element, a contour line can be determined that represents the boundary between the metallographic structure containing Mg and the metallographic structure not containing Mg. The metallographic structure not containing Mg surrounded by this contour line can be identified as the η-Zn phase. A person skilled in the art can easily distinguish the η-Zn phase from the surrounding hard structure 113 through visual identification.

[0182] Determine the outline of the η-Zn phase within the field of view during SEM observation as described above and manually draw this outline using various image analysis applications (e.g., ImageJ). Binarizing the image within the image analysis application makes it easy to determine whether black precipitates corresponding to the α phase are present within the η-Zn phase. For this purpose, the binarization threshold can be set to, for example, 200 in the Brightness / Contrast setting.

[0183] Next, for the η-Zn phase identified as described above, it is determined whether there is an α phase inside it. As described above, when observing using a reflected electron image, the α phase is visually identified as a black precipitate (i.e., black particles), while the η-Zn phase is visually identified as a white parent phase. Therefore, the α precipitated η phase 111 focused on in this embodiment is as follows: Figure 4 As shown schematically, a phase in which black particles are dispersed in a white matrix is ​​observed. Figure 4 In FIG, the outline shown by the dotted line corresponds to the outline of the η-Zn phase described above.

[0184] Therefore, by observing the reflected electron image as described above, the phase in which the black particles are dispersed in the white matrix is ​​determined, and then point analysis based on SEM-EPMA is performed. Focusing on one of the phases in which the black particles are dispersed in the white matrix, as shown in FIG. Figure 4 As shown schematically, a spot analysis using SEM-EPMA was performed on an arbitrary 5 μm x 5 μm area encompassing both the black particles and the white matrix phase. The results of the spot analysis indicate that regions with a Zn content of 90 atomic % or greater and an Al content of 0.05 to 10.00 atomic % can be identified as the α phase 121 within the η matrix phase 123. In this case, any black phase surrounding the region identified as the α phase can be uniformly identified as the α phase.

[0185] By the method as described above, it is possible to determine the region of the α precipitation η phase 111 in the region of 120 μm × 100 μm at any position on the surface of the coating 103. On this basis, various image analysis applications (such as ImageJ, etc.) are used to calculate the area ratio of the determined region. Specifically, on the basis of calculating the area of ​​the region equivalent to α precipitation η phase 111 by the image analysis application, the area of ​​the obtained α precipitation η phase 111 is divided by the area of ​​the entire visual field, thereby being able to obtain the area ratio of the α precipitation η phase 111 in the visual field of interest.

[0186] The above-described measurement / calculation process is performed at five arbitrary locations, and the average of the five obtained area ratios is calculated. The average thus obtained average is taken as the average area ratio of the α-precipitated η phase 111.

[0187] 《About Chemical Conversion Treatment Coating Layer 105》

[0188] Return again Figure 2B The chemical conversion coating layer 105 preferably included in the first member 10 of this embodiment will be described. Figure 2BAs schematically shown, the chemical conversion coating layer 105 is provided on the surface of the plating layer 103 in the bonding area, and more preferably, is provided on the entire surface of the plating layer 103. In addition, at least a portion of the chemical conversion coating layer 105 is in contact with the adhesive layer 30. Thus, the first member 10 is bonded to the second member 20 via the chemical conversion coating layer 105 through the adhesive layer 30.

[0189] As the chemical conversion coating layer 105 of this embodiment, various chemical conversion coating layers may be provided, such as a chromate chemical conversion coating layer, a phosphate-based chromate-free chemical conversion coating layer, and a zirconium-based chromate-free chemical conversion coating layer.

[0190] Among these, a silicon-based chromate-free chemical conversion coating layer, as described below, is more preferably provided as the chemical conversion coating layer 105. Providing a silicon-based chromate-free chemical conversion coating layer as the chemical conversion coating layer 105 can further improve the bonding durability of the adhesively bonded structure 1. This silicon-based chromate-free chemical conversion coating layer is described in detail below.

[0191] A more preferred form of the chemical conversion coating layer 105 is a silicon-based chromate-free chemical conversion coating layer containing a silicon compound having at least one of Si-O bonds and Si-OH bonds. This silicon compound may be an organic silicon compound or an inorganic silicon compound. When an organic silicon compound is contained as the silicon compound, a more preferred form of the chemical conversion coating layer 105 is a silicon-based chromate-free chemical conversion coating layer having at least one of Si-O bonds and Si-OH bonds and Si-C bonds. When an organic silicon compound is contained as the silicon compound, the organic silicon compound constitutes an organic compound phase. When an inorganic silicon compound is contained as the silicon compound, the inorganic silicon compound constitutes an inorganic compound phase.

[0192] In addition, from the viewpoint of convenience in forming the chemical conversion coating layer 105 , it is preferred that an organic silicon compound be used as the main silicon compound.

[0193] The organosilicon compound described above is not particularly limited as long as it has at least one of a Si-C bond and a Si-O bond or a Si-OH bond. For example, organosilicon compounds having a glycidoxy group or a mercapto group are preferably used. Using an organosilicon compound having a glycidoxy group or a mercapto group as the organosilicon compound allows for the formation of Si-O-Me bonds, as described in detail below, to be achieved in a more favorable state, thereby achieving long-term adhesive durability.

[0194] It should be noted that, in addition to organosilicon compounds having a glycidoxy group or a mercapto group, organosilicon compounds having, for example, an amino group, a vinyl group, a methacryloyl group, etc. may also be present in the organosilicon compounds. However, the verification results of the present inventors and others show that when organosilicon compounds having an amino group, a vinyl group, a methacryloyl group, etc. are used, the reaction of the organosilicon compound inside the chemical conversion coating layer 105 with the resin constituting the organic resin phase is further promoted compared to the reaction at the interface between the steel member 101 and the plating layer 103 and the chemical conversion coating layer 105, making it difficult to obtain long-term bonding durability. Therefore, from the viewpoint of achieving long-term bonding durability by preventing the infiltration of electrolytes such as water, it is preferred to use organosilicon compounds having a glycidoxy group or a mercapto group. It should be noted that as organosilicon compounds having a glycidoxy group or a mercapto group, commercially available organosilicon compounds that meet the conditions can be used, or organosilicon compounds produced by organic synthesis can be used.

[0195] Furthermore, when the chemical conversion coating layer 105 is a more preferred embodiment of a silicon-based chromate-free chemical conversion coating layer containing an inorganic compound, the strength of the chemical conversion coating layer is increased, thereby improving the bonding strength. Examples of the inorganic silicon compound constituting the inorganic compound phase include colloidal silica and fumed silica.

[0196] Furthermore, as the chemical conversion coating layer 105, a more preferred embodiment of a silicon-based chromate-free chemical conversion coating layer includes, in addition to the aforementioned silicon compound, an organic resin phase containing at least one of a carbamate group, an epoxy group, and an ester group. Specifically, as the chemical conversion coating layer 105, a more preferred embodiment of a silicon-based chromate-free chemical conversion coating layer includes at least one of a carbamate group, an epoxy group, or an ester group; and a silicon compound having at least one of a Si-O bond and a Si-OH bond. More specifically, the organic resin phase having the aforementioned specific functional groups primarily exists as resin particles, with the resin particles dispersed within the silicon compound phase.

[0197] By the presence of a silicon compound having the above-mentioned bond in the chemical conversion coating layer 105, a chemical bond such as a Si-O-Me bond is formed between the elements constituting the first component 10. Here, Me represents the main metal element constituting the first component 10. Specifically, as the above-mentioned Me, there are Fe from the steel component 101, and / or Zn, Al, and Mg from the plating layer 103. By forming such a primary bond, the bonding state between the steel component 101 and / or the plating layer 103 and the chemical conversion coating layer 105 becomes stronger, and the adhesion between the steel component 101 and the plating layer 103 and the chemical conversion coating layer 105 is further improved. As a result, a state is achieved in which it is difficult for water to penetrate from the outside into the interface between the steel component 101 and the plating layer 103 and the chemical conversion coating layer 105. As a result, in the adhesive joint structure 1 of this embodiment, the bonding durability can be improved.

[0198] In a more preferred embodiment of the chemical conversion coating layer 105 , the total volume ratio of the organic compound phase and the inorganic compound phase is preferably in the range of 16% to 84% by volume relative to the total volume of the chemical conversion coating layer.

[0199] If the combined volume ratio of the organic compound phase and the inorganic compound phase relative to the total volume of the chemical conversion coating layer is less than 16 volume %, Si-O-Me bonds may not be sufficiently formed. The combined volume ratio of the organic compound phase and the inorganic compound phase is more preferably 20 volume % or greater, and even more preferably 30 volume % or greater.

[0200] On the other hand, if the volume ratio of the organic compound phase and the inorganic compound phase relative to the total volume of the chemical conversion coating layer exceeds 84 volume %, the adhesion between the adhesive layer 30 and the chemical conversion coating layer may be reduced. The combined volume ratio of the organic compound phase and the inorganic compound phase is more preferably 80 volume % or less, and even more preferably 70 volume % or less.

[0201] It should be noted that when judging the total volume ratio of the organic compound phase and the inorganic compound phase from the cross-section of the chemical conversion treatment coating layer, the area ratio of the total organic compound phase and the inorganic compound phase relative to the cross-sectional area is calculated in the cross-section at any position of the chemical conversion treatment coating layer, and the total volume ratio of the organic compound phase and the inorganic compound phase can be judged.

[0202] In the more preferred embodiment of the chemical conversion coating layer 105 , the volume ratio of the organic compound phase in a silicon-based chromate-free chemical conversion coating layer is preferably within a range of 16% to 84% by volume relative to the total volume of the chemical conversion coating layer.

[0203] When the volume ratio of the organic compound phase relative to the total volume of the chemical conversion coating layer is less than 16 volume %, Si-O-Me bonds may not be sufficiently formed. The volume ratio of the organic compound phase is more preferably 20 volume % or more, and even more preferably 30 volume % or more.

[0204] On the other hand, if the volume ratio of the organic compound phase exceeds 84 volume % relative to the total volume of the chemical conversion coating layer, the adhesion between the adhesive layer 30 and the chemical conversion coating layer 105 may be reduced. The volume ratio of the organic compound phase is more preferably 80 volume % or less, and even more preferably 70 volume %.

[0205] It should be noted that when determining the volume ratio of the organic compound phase from the cross section of the chemical conversion coating layer, the area ratio of the organic compound phase relative to the cross-sectional area at any position of the cross section of the chemical conversion coating layer can be calculated and determined as the volume ratio of the organic compound phase.

[0206] In the more preferred embodiment of the chemical conversion coating layer 105 , the volume ratio of the inorganic compound phase in a silicon-based chromate-free chemical conversion coating layer is preferably 10% by volume or less relative to the total volume of the chemical conversion coating layer.

[0207] If the volume ratio of the inorganic compound phase exceeds 10% by volume, the adhesion between the steel member 101 and the plating layer 103 and the chemical conversion coating layer 105 may be reduced. In addition, in a more preferred embodiment of the chemical conversion coating layer 105, the chemical conversion coating layer does not need to contain an inorganic compound phase, so the lower limit is 0% by volume.

[0208] When determining the volume ratio of the inorganic compound phase from a cross-section of the chemical conversion coating layer, the area ratio of the inorganic compound phase relative to the cross-sectional area at any cross-section position of the chemical conversion coating layer can be calculated and used as the volume ratio of the inorganic compound phase. For example, the inorganic silicon compound can be determined based on its constituent elements by performing elemental analysis using EPMA at any cross-section position of the chemical conversion coating layer.

[0209] The volume ratio of the inorganic silicon compound and / or the organic silicon compound can be determined based on an SEM image obtained by observing a cross section using a scanning electron microscope (SEM) after elemental analysis using the above-described EPMA.

[0210] In addition, as the chemical conversion coating layer 105, in the silicon-based chromate-free chemical conversion coating layer which is a more preferred form, resin particles as an example of an organic resin phase are preferably dispersed in the organic compound phase. As described above, the resin particles have one or more functional groups selected from the group consisting of a carbamate group, an epoxy group, and an ester group. These functional groups are functional groups that are also contained in large quantities in the resin constituting the adhesive. Therefore, by containing resin particles having the functional groups as described above in the chemical conversion coating layer, the adhesion of the interface between the chemical conversion coating layer 105 and the adhesive layer 30 is improved. As a result, a state is achieved in which it is difficult for water to penetrate the interface between the chemical conversion coating layer 105 and the adhesive layer 30 from the outside. Thus, in the adhesive bonding structure 1 of the present embodiment, the bonding durability between the chemical conversion coating layer 105 and the adhesive layer 30 can be improved.

[0211] Here, the resin particles constituting the organic resin phase as described above are not particularly limited as long as they are resin particles having one or more functional groups among a carbamate group, an epoxy group, and an ester group. The resin particles can be water-dispersible water-based resins dispersed in water, or solvent-based resins dispersed in an organic solvent, or both. However, from the aspect of manufacturing cost and environmental adaptability, the above-mentioned resin particles are preferably water-based resins. In addition, the resin constituting the resin particles preferably has a main skeleton comprising carbon atoms.

[0212] Examples of the water-based resin include water-dispersible resins such as polyurethane resins, epoxy resins, polyester resins, and mixed resins of two or more of these resins.

[0213] When a polyester resin is used as the water-based resin, the molecular weight is preferably 10,000 to 30,000. If the molecular weight is less than 10,000, it may be difficult to ensure sufficient processability. On the other hand, if the molecular weight exceeds 30,000, the number of binding sites of the resin itself is reduced, and it may be difficult to ensure excellent adhesion with the adhesive layer 30. In addition, when a curing agent such as melamine is used for cross-linking, the cross-linking reaction may not proceed sufficiently, and the performance of the chemical conversion coating layer may be reduced.

[0214] When a polyurethane resin is used as the water-based resin, the polyurethane resin is preferably in the form of an emulsion with an emulsion particle size of 10 to 100 nm (more preferably 20 to 60 nm). If the emulsion particle size is too small, the cost may increase. On the other hand, if the emulsion particle size is too large, the gaps between the emulsions become larger during film formation, and thus the barrier properties of the chemical conversion coating layer may be reduced. Examples of polyurethane resin types include ether-based, polycarbonate-based, and ester-based. These polyurethane resins can be used alone or in combination.

[0215] On the other hand, examples of solvent-based resins include polyester resins, polyurethane resins, epoxy resins, and mixed resins of two or more of these resins.

[0216] Here, in the chemical conversion coating layer 105, which is a more preferred embodiment of a silicon-based chromate-free chemical conversion coating layer, the resin contained in the coating layer may be a cross-linked resin having a cross-linked structure or a non-cross-linked resin having no cross-linked structure. As a cross-linking agent (curing agent) for imparting a cross-linked structure to the resin, melamine, isocyanate, silane compound, zirconium compound, titanium compound, etc. are preferably used.

[0217] The amount of the crosslinking agent added is preferably 5 to 30 parts by mass relative to 100 parts by mass of the resin solids. When the amount of the crosslinking agent added is less than 5 parts by mass, the crosslinking reaction with the resin may be reduced, and the performance as a coating may become insufficient. On the other hand, when the amount of the crosslinking agent added exceeds 30 parts by mass, the crosslinking reaction may proceed excessively, the chemical conversion coating layer may become too hard, and the processability may be reduced. In addition, when using silane compounds, zirconium compounds, or titanium compounds as crosslinking agents, if the amount of the crosslinking agent added is more than 30 parts by mass, the coating stability may be further reduced.

[0218] Here, in a more preferred embodiment of the chemical conversion coating layer 105, a silicon-based chromate-free chemical conversion coating layer, whether the chemical conversion coating layer contains at least one of a urethane group, an epoxy group, and an ester group can be determined by the following method. Furthermore, the presence or absence of Si-C bonds, Si-O bonds, and Si-OH bonds can also be determined by the following method.

[0219] First, the portion of the adhesively bonded structure 1 where the chemical conversion coating layer 105 is disposed is cut by oblique cutting to expose its cross section. Next, the obtained cross section is further polished to obtain a cross-sectional sample in the thickness direction of the chemical conversion coating layer 105 of the first component 10. Next, the portion of the chemical conversion coating layer 105 of the obtained cross-sectional sample is analyzed using a microscopic infrared spectrometer to obtain an infrared absorption spectrum of the cross-sectional sample of interest. In the obtained infrared absorption spectrum, the presence or absence of the above-mentioned functional groups and / or bonds is determined based on whether vibration peaks from carbamate groups, epoxy groups, ester groups, Si-O bonds, Si-C bonds, and Si-OH bonds are observed.

[0220] Specifically, in the obtained infrared absorption spectrum, at 910 cm -1 If a peak is observed near 1550 cm -1 Nearby and 1740cm -1If a peak is observed near 1720-1740 cm -1 When a peak is observed near this region, it is determined that an ester group is contained.

[0221] In addition, in the infrared absorption spectrum obtained, the -1 If a peak is observed near 1000-1100 cm -1 If a peak is observed near 3650-3690 cm -1 When a peak is observed nearby, it is judged that a Si—OH bond is contained.

[0222] It should be noted that the cutting angle in the oblique cutting may be any angle as long as the chemical conversion coating layer 105 can be sufficiently expanded.

[0223] Here, we focus on the case where, as a chemical conversion coating layer 105, a silicon-based chromate-free chemical conversion coating layer, which is a more preferred embodiment, the chemical conversion coating layer 105 is analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS) while Ar sputtering from the adhesive layer 30 side toward the steel member 101 side, so as to include any portion of the interface between the steel member 101 and the plating layer 103. In this case, the following analysis results are preferably obtained. Specifically, in the TOF-SIMS analysis results, peaks corresponding to Si-O-Me bonds (Me: Fe, Zn, Al, Mg) are preferably observed, and the count value of the peak representing the Si-O-Me bond is preferably 15 or greater. In addition, the intensity (arbitrary unit) (Intensity (au)) in the total ion correction value (the value obtained by dividing the peak count of Si-O-Me bond by the total value of all detected secondary ion counts) is preferably 1.0×10 -3 Specifically, the value obtained by dividing the count value of the peak representing the Si-O-Me bond by the total value of all secondary ion counts detected in the mass scan range m / z = 0 to 300 (Total Ion Correction Value) is preferably 1.0×10 -3 above.

[0224] Here, the peak corresponding to the Si-O-Me bond is observed at a characteristic position of each element Me according to the specific type of element Me. For example, in the case of Me = Fe, the representative peak corresponding to the Si-O-Fe bond is the peak observed at a mass (m / z) of 100 ± 0.1 in the TOF-SIMS analysis results. In the case of Me = Zn, the representative peak corresponding to the Si-O-Zn bond is the peak observed at a mass (m / z) of 108 ± 0.1 in the TOF-SIMS analysis results. In the case of Me = Al, the representative peak corresponding to the Si-O-Al bond is the peak observed at a mass (m / z) of 71 ± 0.1 in the TOF-SIMS analysis results. In the case of Me = Mg, the representative peak corresponding to the Si-O-Mg bond is the peak observed at a mass (m / z) of 68 ± 0.1 in the TOF-SIMS analysis results.

[0225] The analysis results indicate that the Si-O-Me bond formation reaction proceeds efficiently at the interface between the steel member 101 and the plating layer 103, and the chemical conversion coating layer 105, resulting in a certain amount or more of Si-O-Me bonds being formed at the interface between the steel member 101 and the plating layer 103, and the chemical conversion coating layer 105. By forming a certain amount or more of Si-O-Me bonds at the interface between the steel member 101 and the plating layer 103, and the chemical conversion coating layer 105, water can be prevented from penetrating the interface between the steel member 101 and the plating layer 103, and the chemical conversion coating layer 105, even when the adhesively bonded structure 1 is exposed to a humid environment, thereby maintaining longer-term bonding durability.

[0226] The count value representing the Si-O-Me bond is more preferably 20 or more, and even more preferably 30 or more. The Total Ion correction value is more preferably 1.3×10 -3 More than 2.0×10 -3 .

[0227] Note that the count value of the peak corresponding to the Si—O—Me bond at the interface between the steel member 101 and the plating layer 103 and the chemical conversion coating layer 105 as described above can be measured as follows.

[0228] First, the steel component 101 and the bonding portion of the plating layer 103 and the chemical conversion coating layer 105 are cut with a 5-degree inclination from the adhesive layer 30 side toward the steel component 101 side using an inclined cutting device (Surface And Interfacial Cutting Analysis System: SAICAS), and Ar sputtering is performed to produce a sample in which the thickness of the adhesive layer 30 is thinned to about 1 μm. For the portion in which the thickness of the adhesive layer 30 is thinned to about 1 μm, Ar sputtering is performed from the adhesive layer 30 side toward the steel component 101 side while TOF-SIMS analysis is performed. After sputtering from the surface to a specified depth with an Ar beam, a TOF-SIMS measurement is performed, and then Ar sputtering is performed in the same manner and a TOF-SIMS measurement is performed. The above operation is repeated to obtain a depth distribution for various elements and bonds. The primary ion species is set to Au. 3+ , the acceleration voltage was set to 30 kV, the sputtering rate was set to about 80 nm / min (SiO2 conversion), and the measurement area was set to 50 μm×50 μm.

[0229] Each ion has a specific mass number. Therefore, in the TOF-SIMS measurement described above, the depth distribution of the theoretical mass number of the target Si-O-Me bond is measured. Based on the depth distribution of the mass corresponding to the Si-O-Me bond and the depth distributions of the Me ions, the main component of the metal part, and the C ions, the main component of the resin, the area from the rising portion of the Me ion count value to the falling portion of the C ion count value to the area where the C ion count value is approximately constant is considered to be the interface. Based on this, the count value corresponding to the Si-O-Me bond at this interface is measured.

[0230] It should be noted that when forming the chemical conversion coating layer 105 of the present embodiment, by appropriately adjusting the selection and content of the raw material serving as the raw material of the organic resin phase and the raw material of the organic compound phase, and appropriately controlling the surface conditions of the steel member 101 and the plating layer 103, the area ratio of the resin particles and the Si-O-Me bond count value in TOF-SIMS can be adjusted to fall within the desired range.

[0231] ◇About other ingredients

[0232] The chemical conversion coating layer 105 may contain other additives in addition to the above components. Examples of other additives include oxide particles, extender pigments, solid lubricants, rust inhibitors, leveling agents, viscosity-imparting agents, pigment anti-settling agents, defoaming agents, and other well-known additives.

[0233] ◇About the average thickness of the chemical conversion coating layer 105

[0234] In this embodiment, the average thickness of the chemical conversion coating layer 105 described above is preferably 0.2 μm or greater per surface of the first member 10. By setting the average thickness per surface of the chemical conversion coating layer 105 to 0.2 μm or greater, the aforementioned effects of providing the chemical conversion coating layer 105 can be reliably achieved. The average thickness per surface of the chemical conversion coating layer 105 is more preferably 0.4 μm or greater, and even more preferably 0.5 μm or greater. On the other hand, by setting the average thickness per surface of the chemical conversion coating layer 105 to 1.5 μm or less, electrical conductivity between the steel member 101 and the plating layer 103 can be ensured via the chemical conversion coating layer 105. This allows, for example, electrodeposition coating of the steel member 101 and the plating layer 103 to be performed via the chemical conversion coating layer 105, or spot welding of the steel member 101 and the plating layer 103 to be performed via the chemical conversion coating layer 105. The average thickness per surface of the chemical conversion coating layer 105 is more preferably 1.2 μm or less, and further preferably 1.0 μm or less.

[0235] It should be noted that the average thickness of the chemical conversion coating layer 105 can be measured as follows. First, any portion of the adhesively bonded structure 1 where the chemical conversion coating layer 105 is provided is cut along the thickness direction of the chemical conversion coating layer 105, thereby exposing its cross section. Next, the obtained cross section is further ground to obtain a cross-sectional sample of the chemical conversion coating layer 105 of the first component 10 in the thickness direction. Next, the portion of the chemical conversion coating layer 105 of the obtained cross-sectional sample is observed using an SEM to obtain an observation image of the cross section of the chemical conversion coating layer 105. For the chemical conversion coating layer 105 present in the field of view of the obtained observation image, the thickness is measured at 5 positions where the field of view is divided into 5 equal parts along the width direction, and the average value is calculated. The average thickness of the chemical conversion coating layer 105 is set to the average value of the values ​​obtained in the 5 fields of view. That is, the average thickness of the chemical conversion coating layer 105 is set to the average value of the thicknesses at a total of 25 locations.

[0236] The first member 10 of the adhesively bonded structure 1 according to the present embodiment has been described in detail above.

[0237] <About the Second Member 20>

[0238] In the adhesively bonded structure 1 of the present embodiment, the material of the second member 20 at least in the adhesive region is not particularly limited, and various metal members and various non-metal members can be used as the material.

[0239] When a metal member is used as the second member, its material may include, for example, iron, titanium, aluminum, magnesium and alloys thereof. Here, as examples of alloys, for example, iron-based alloys (including stainless steel), Ti-based alloys, Al-based alloys, Mg-based alloys, etc. may be listed. The material of the metal member is preferably a steel material (steel), iron-based alloys, titanium and aluminum, and more preferably a steel material having a higher tensile strength than other metal types. As such steel materials, for example, there are steel materials specified in Japanese Industrial Standards (JIS), etc., and carbon steel, alloy steel, high-tensile steel, etc. used for general structures and / or mechanical structures may be listed. Specific examples of such steel materials include cold-rolled steel, hot-rolled steel, hot-rolled steel plates for automobile structures, hot-rolled high-tensile steel plates for automobile processing, cold-rolled steel plates for automobile structures, cold-rolled high-tensile steel plates for automobile processing, and high-tensile steel materials generally referred to as hot stamping materials that have been quenched during hot working. The composition of such steel materials is not particularly limited, and in addition to Fe and C, one or more of Si, Mn, S, P, Al, N, Cr, Mo, Ni, Cu, Ca, Mg, Ce, Hf, La, Zr, and Sb may be contained. To achieve the desired material strength and formability, one or more of these optional additive elements may be appropriately selected, and their contents may be appropriately adjusted.

[0240] When the metal component is made of steel, any surface treatment may be applied to the steel. Examples of surface treatments include, but are not limited to, various plating treatments such as galvanizing, aluminum plating, and tin plating; chemical conversion treatments such as zinc phosphate treatment, chromate treatment, and chromate-free treatment; and physical surface roughening such as sandblasting or chemical etching. Furthermore, a variety of surface treatments may be applied. It is preferred that at least one surface treatment be performed to impart rust resistance.

[0241] In particular, among steel materials, plated steel members that have been plated have excellent corrosion resistance and are therefore preferred as the material for the second member 20. Examples of particularly preferred plated steel members for the second member 20 include galvanized steel sheets, Ni-plated steel sheets, alloyed Ni-plated steel sheets obtained by heat-treating these sheets to diffuse Fe into the Ni plating, Al-plated steel sheets, tin-plated steel sheets, and chrome-plated steel sheets.

[0242] Among the various types of plated steel sheets described above, galvanized steel sheets have excellent corrosion resistance and are therefore suitable as the raw material for the second member 20. In particular, alloyed hot-dip galvanized steel sheets, which are obtained by galvanizing a steel sheet and then alloying it to diffuse iron in the galvanized steel, further suppress the strength reduction of the adhesive over time and are therefore preferred as the raw material for the second member 20.

[0243] Therefore, as the blank of the second component 20, it is preferred to use a high-strength alloyed hot-dip galvanized steel plate, for example, an alloyed hot-dip galvanized steel plate with a tensile strength of 980 MPa or more, and more preferably an alloyed hot-dip galvanized steel plate with a tensile strength of 1180 MPa or more. In this way, the bonding strength between the first component 10 and the second component 20 can be further improved. In this case, when the adhesive joint structure 1 is subjected to stress, the adhesive layer 30 as a whole can be subjected to stress, so that the effect of the bonding durability of the adhesive joint structure of this embodiment can be further obtained. It should be noted that the tensile strength of the steel plate can be measured in accordance with JIS Z2241:2011.

[0244] Hereinafter, the hot-dip galvanized steel sheet and the alloyed hot-dip galvanized steel sheet will be described in detail.

[0245] The steel plate used as the base material for hot-dip galvanized steel sheets and alloyed hot-dip galvanized steel sheets can be a commonly known steel plate. Examples of such steel plates include hot-rolled mild steel plates and strips described in JIS G3131:2018, hot-rolled steel plates and strips for automobiles described in JIS G3113:2018, and cold-rolled steel plates and strips described in JIS G3141:2017. High-strength steel plates used in automotive applications are more preferably used as the base material. As mentioned above, high-strength steel plates with a tensile strength of 980 MPa or greater, and even higher tensile strength steel plates with a tensile strength of 1180 MPa or greater, are more preferably used.

[0246] In addition, as the blank of the second component 20, the plated steel plate having the steel component and the plating layer described in the above-mentioned first component 10 can be used. As the blank of the second component 20, the same blank as the blank of the above-mentioned first component 10 (that is, the plated steel plate having the steel component 101, the plating layer 103 and the chemical conversion treatment coating layer 105) can be used.

[0247] Alternatively, as the raw material of the second member 20 , a surface-treated metal member obtained by forming the chemical conversion coating layer 105 of the same material as that described for the first member 10 on the various metal members described above may be used.

[0248] Furthermore, in the adhesively bonded structure 1 of this embodiment, various non-metallic members such as various resin materials, and / or fiber-reinforced plastics (FRP) in which a matrix resin is composited with reinforcing fibers, and / or ceramic materials may be used as the blank of the second member 20. Examples of the reinforcing fibers used in the fiber-reinforced plastics include glass fibers and carbon fibers.

[0249] The second member 20 in the adhesively bonded structure 1 of the present embodiment has been described in detail above.

[0250] <About Adhesive Layer 30>

[0251] In the adhesively joined structure 1 of the present embodiment, the adhesive layer 30 is arranged between the first member 10 and the second member 20 in the bonding region, and bonds the first member 10 and the second member 20 together.

[0252] The adhesive layer 30 is mainly composed of an adhesive. The effect of the first component 10 is not impaired by the type of adhesive constituting the adhesive layer 30. Therefore, there is no particular limitation on the adhesive that can be used for the adhesive layer 30. For example, epoxy resin adhesives, polyester resin adhesives, polyurethane resin adhesives, etc., and / or adhesives in which rubber and / or elastomers are mixed with these adhesives, adhesives imparted with conductivity, etc. can be used. Among the above, from the viewpoint of initial bonding strength, the adhesive layer 30 preferably contains an epoxy resin adhesive or a polyurethane resin adhesive (i.e., a thermosetting adhesive).

[0253] Furthermore, when the first member 10 of this embodiment has a chemical conversion coating layer 105, the resin of the adhesive constituting the adhesive layer 30 preferably has a common chemical structure with at least one of the resins in the chemical conversion coating layer 105. This can further improve the initial adhesion between the adhesive layer 30 and the chemical conversion coating layer 105, and can further enhance the bonding strength of the adhesively bonded structure 1.

[0254] For example, the resin constituting the adhesive of the adhesive layer 30 may have a common main skeleton with at least one of the resins in the chemical conversion coating layer 105. Alternatively, the resin constituting the adhesive of the adhesive layer 30 may have a common side chain functional group with at least one of the resins in the chemical conversion coating layer 105.

[0255] The adhesive layer 30 in the adhesively bonded structure 1 of the present embodiment has been described in detail above.

[0256] <Regarding Bonding Length of Adhesive-Jointed Structure 1>

[0257] Next, refer to Figure 5 The bonding length of the adhesively bonded structure 1 of the present embodiment will be described. Figure 5 It is an explanatory diagram for explaining the bonding length of the adhesively bonded structure according to the present embodiment.

[0258] In the adhesively bonded structure 1 of this embodiment, the focus was on an arbitrary position at the portion where the first member 10 and the second member 20 were bonded via the adhesive layer 30. A cross-section of the first member 10, the second member 20, and the adhesive layer 30, taken along the stacking direction, was observed using an electron microscope (more specifically, a scanning electron microscope). The observation field was 130 μm × 100 μm in size, and the observation position was determined so that the interface between the steel member 101 of the first member 10, the plating layer 103 (including the chemical conversion coating layer 105, if present), and the adhesive layer 30 existed within the field of view.

[0259] In this observation, the total length of the contact between the plating layer 103 or the steel member 101 and the adhesive layer 30 is recorded as the bonding length L. In addition, when the chemical conversion coating layer 105 is present, the total length of the contact between the chemical conversion coating layer 105, the plating layer 103 or the steel member 101 and the adhesive layer 30 is recorded as the bonding length L. Figure 5 In the example shown, the length of the line segment indicated by the bold line corresponds to the bonding length L. In such observation, the length of the observation field in the direction perpendicular to the surface normal direction of the steel member 101 (ie, 130 μm) is denoted as L0.

[0260] In the adhesive bonding structure 1 of this embodiment, the ratio L / L0 of these two lengths is greater than 1.10. The ratio L / L0 being greater than 1.10 means that the bonding length L is longer than the length L0 of the observation field. The realization of such a state suggests that the surfaces of the coating 103 and the chemical conversion coating layer 105 are uneven and have undulations. The reason for achieving such a state is not certain, but the following reasons are speculated.

[0261] That is, the coating 103 possessed by the first component 10 of the present embodiment is in a state in which the α-precipitated η phase 111 as a soft tissue is dispersed in the hard tissue 113, as described above. In the case where the first component 10 is intended to be used to manufacture the adhesive bonding structure 1, it is believed that strain will be imparted to the coating 103 during the process of manufacturing the first component 10, the process of processing the first component 10 into the desired shape so as to realize the desired shape of the adhesive bonding structure 1, the process of applying an adhesive to the first component 10 and pressing it with the second component 20, etc. The strain imparted in such a process is concentrated on the α-precipitated η phase 111 as a relatively soft tissue. As a result, it is believed that cracks (cracks) are generated in the hard tissue 113 starting from the α-precipitated η phase 111. It is speculated that the cracks generated in this way exhibit the so-called anchoring effect, thereby achieving the above-mentioned ratio L / L0. That is, it can be said that the presence of the α-precipitated η phase 111 in the plating layer 103 of the first member 10 , one of the constituent members of the adhesively bonded structure 1 of this embodiment, in a specific amount (i.e., average area ratio) is an important factor in achieving the above-mentioned ratio L / L0.

[0262] The ratio L / L0 being 1.10 or greater means that the adhesively bonded structure 1 of the present embodiment exhibits the above-described anchoring effect. The adhesively bonded structure 1 that achieves such a ratio L / L0 exhibits excellent bonding durability due to the anchoring effect.

[0263] When the ratio L / L0 is less than 1.10, the above-mentioned anchoring effect is not sufficiently exhibited, and the adhesively bonded structure cannot exhibit excellent bonding durability. In the adhesively bonded structure 1 of this embodiment, the ratio L / L0 is preferably 1.30 or more, more preferably 1.60 or more.

[0264] On the other hand, the upper limit of the ratio L / L0 is not particularly specified, and the larger the better, but approximately 1000.00 is the actual upper limit.

[0265] To measure the bonding length L, SEM observation can be performed in the same manner as for observing the metallographic structure of the plating layer 103. This observation focuses on an area measuring 130 μm in width and 100 μm in height, encompassing the entire width of the adhesive layer 30. Using a length measurement application included with the SEM, etc., the total length of contact between the steel member 101, plating layer 103, or chemical conversion coating layer 105 and the adhesive layer 30 in this area is measured. This measurement process is performed at five arbitrary locations, and the average of the five measured values ​​is calculated. This average value is defined as the bonding length L.

[0266] It should be noted that, in the above description about the bonding length L, Figure 2BThe laminated structure 1 shown in FIG. is exemplified as an example, but in the case of Figure 2A In the case of the adhesively bonded structure 1 having the laminated structure shown, the bonding length L is the total length of the contact between the plating layer 103 or the steel member 101 and the adhesive layer 30 .

[0267] Above, refer to Figures 1 to 5 The adhesively bonded structure 1 of this embodiment has been described in detail.

[0268] It should be noted that, in the above embodiment, the first member 10 and the second member 20 are bonded together only by the adhesive layer 30 , but the present invention is not limited thereto, and adhesive bonding using an adhesive layer may be combined with other bonding methods (second bonding).

[0269] The second joining method that can be combined with adhesive joining is not particularly limited, and any joining method can be adopted. Specific examples of such joining methods include fusion joining, non-fusion joining, and mechanical joining.

[0270] Examples of fusion welding include spot welding, arc welding, and laser welding. Fusion welding can be applied when the second member includes a portion formed of a metal member. It should be noted that fusion welding can be performed without removing the adhesive layer, but if the adhesive layer is conductive, it can be performed without removing the adhesive layer.

[0271] Examples of non-melting joining include friction stir joining, diffusion joining, and pressure joining. Examples of mechanical joining include rivet joining and / or joining by screws.

[0272] (Regarding the method for manufacturing an adhesively bonded structure)

[0273] Hereinafter, an example of a method for producing the adhesively bonded structure according to the present embodiment will be described.

[0274] <About the Manufacturing Method of the First Member 10>

[0275] First, an example of a method for manufacturing the first member 10 will be described.

[0276] The first member 10 constituting the present embodiment has Figure 2B The plated steel member of the laminated structure shown is manufactured by forming a plating layer 103 on the surface of the steel member 101 using the above-mentioned steel member 101 as a base material, and then forming a chemical conversion coating layer 105 on the surface of the plating layer 103 using a predetermined chemical conversion agent.

[0277] Furthermore, in order to achieve the aforementioned ratio L / L0 when manufacturing the adhesively bonded structure 1 of this embodiment, as previously described, it is important to impart strain to the plating layer 103 during the process of manufacturing the first member 10, processing the first member 10 into a desired shape to achieve the desired shape of the adhesively bonded structure 1, and applying adhesive to the first member 10 and press-bonding it to the second member 20. The following description will take as an example the case of intentionally imparting strain during the manufacture of the first member 10.

[0278] Here, when forming the coating 103 on the steel member 101, in addition to the hot-dip coating method, other methods can be applied, such as spraying, cold spraying, sputtering, vapor deposition, and electroplating. However, in order to form a coating with a thickness generally used in automobiles, etc., the hot-dip coating method is most preferred in terms of cost.

[0279] The plated steel member (steel member 101 having the plating layer 103) obtained by the above method is subjected to a specific heat treatment process described below. This forms an α-precipitated η phase 111 in the plating layer 103. It is then speculated that by applying strain to the plated steel member that has undergone the heat treatment process using various methods, cracks are generated, which are the main cause for achieving the above-mentioned ratio L / L0.

[0280] Next, a predetermined chemical conversion treatment agent is applied to the surface of the formed plating layer 103, and the chemical conversion treatment agent is dried and cured, thereby forming a chemical conversion treatment film layer 105 on the surface of the plating layer 103. The drying and curing conditions for the chemical conversion treatment agent are not particularly specified; the temperature and treatment time required to vaporize the solvent and the treatment time may be appropriately set based on the solvent that constitutes the chemical conversion treatment agent. For example, a drying and curing time of 5 seconds to 30 minutes may be sufficient under the temperature conditions of 80°C to 250°C.

[0281] It should be noted that when a chemical conversion agent is applied after strain is applied to the plating layer 103, cracks generated by the strain may be filled by the chemical conversion agent. However, within the range of the average thickness of the chemical conversion coating layer 105 described above, it is difficult to assume that all generated cracks are completely filled, and it is believed that the anchoring effect described above is exhibited.

[0282] Hereinafter, an example of a method for producing a plated steel member using a hot-dip coating method to obtain a blank to be the first member 10 of the present embodiment will be described in detail.

[0283] In the manufacturing process of the plated steel sheet, first, a steel member 101 serving as a base material is rolled to a desired thickness by the Sendzimir method, and then wound into a coil and placed in a hot-dip coating line.

[0284] In a hot-dip coating line, steel sheets are continuously threaded onto a strip while being unwound from a coil. The steel sheets are then subjected to a heat reduction treatment at 800°C in an N2-5% H2 atmosphere, in an annealing facility installed in the line, under a low-oxidation environment (e.g., an oxygen concentration of 20 ppm or less). The steel sheets are then air-cooled with N2 gas to a temperature of approximately +20°C above the subsequent coating bath temperature, and then immersed in the coating bath.

[0285] Here, a molten plating alloy having the above-mentioned chemical composition is prepared in a plating bath, and the bath temperature of the plating bath is equal to or higher than the melting point of the plating alloy (eg, approximately 400 to 500° C.).

[0286] When preparing the material for the plating alloy, it is preferable to use pure metals (purity 99% or higher) as the alloying material. First, the alloying metals are mixed in predetermined amounts to form the composition of the aforementioned plating layer. The alloy is then completely melted in a high-frequency induction furnace and / or an arc furnace under vacuum or inert gas substitution to form the alloy. This alloy, mixed with the predetermined composition (the aforementioned plating layer composition), is then melted in the atmosphere, and the resulting melt is used as the plating bath.

[0287] It should be noted that, in the production of the above-mentioned plating alloy, there is no particular restriction on using pure metals, and existing Zn alloys, Mg alloys, and Al alloys can also be melted and used. In this case, there is no problem as long as a predetermined composition alloy with few impurities is used.

[0288] After immersing the steel member in the above-described plating bath, it is pulled out at a predetermined speed. At this time, the coating deposition amount is controlled, for example, by using N2 wiping gas, so that the formed coating layer 103 has the desired thickness. Regarding conditions other than the bath temperature, general plating operating conditions can be applied, and no special equipment and / or conditions are required.

[0289] Next, the molten plating alloy on the steel sheet is subjected to the following first and second cooling steps, thereby forming the molten plating alloy into a plating layer 103 and generating an α-precipitated η phase 111 in the plating layer 103. The first and second cooling steps are described in detail below.

[0290] The first cooling process is a cooling process performed when the temperature of the plating alloy is below the bath temperature and above 240°C. In this first cooling process, the plated steel member in the temperature range described above is quenched at an average cooling rate of 15.0°C / second or more. Here, when the average cooling rate is less than 15.0°C / second, the concentration of Al dissolved in the η phase decreases, and the driving force for the subsequent precipitation of the α phase in the η phase is insufficient, resulting in difficulty in forming the α-precipitated η phase. As a result, cracks will not be generated when strain is applied, and the bonding length described above cannot be achieved. It should be noted that when hot-dip plating is used in the plating process, the first cooling process is performed just after the steel member comes out of the plating bath. As a result, Al is dissolved in the solidifying η-Zn phase.

[0291] Here, the average cooling rate is preferably 25.0° C. / second or higher. The upper limit of the average cooling rate is not particularly specified, but approximately 90.0° C. / second is a practical upper limit, for example.

[0292] Then, when the temperature of the plating alloy (plating) is within the range of less than 240°C and more than 70°C, a second cooling process is implemented. In this second cooling process, the plated steel sheet in the temperature range described above is slowly cooled at an average cooling rate of less than 1.0°C / second. Here, when the average cooling rate exceeds 1.0°C / second, the time for the α phase to precipitate from the η phase cannot be ensured, and the formation of the α precipitation η phase becomes difficult. As a result, Al dissolved in the η-Zn phase in the first cooling process precipitates as the α phase, thereby softening the η-Zn phase to become the α precipitation η phase 111, and a hard structure 113 is present around the α precipitation η phase 111. Here, the above-mentioned average cooling rate is preferably less than 0.5°C / second.

[0293] As described above, by undergoing two cooling steps of rapid cooling in a temperature range below the bath temperature and above 240°C and slow cooling in a temperature range below 240°C and above 70°C, the α-precipitated η phase 111 can be formed in the coating layer 103 at a desired average area ratio.

[0294] Note that there is no particular limitation on the cooling state from 70° C. to room temperature, and cooling to room temperature may be performed by various methods.

[0295] Here, the interval from the completion of the first cooling step to the start of the second cooling step is preferably within 3 seconds, and the second cooling step is preferably started immediately after the completion of the first cooling step. If the interval from the completion of the first cooling step to the start of the second cooling step exceeds 3 seconds, an undesirable cooling process occurs, and the desired α-precipitated η phase 111 cannot be generated.

[0296] It should be noted that, without performing either the first cooling step or the second cooling step as described above, the desired α-precipitated η phase 111 cannot be achieved. By performing both the first cooling step and the second cooling step as described above, the α-precipitated η phase 111 can be generated in the coating layer 103 at a desired average area ratio, and soft tissue can be appropriately introduced into the coating layer 103.

[0297] Furthermore, if an alloying heat treatment step (e.g., a heat treatment step involving heating to a plate temperature of approximately 480 to 550°C) is performed after the second cooling step, which is often performed in the manufacture of alloyed hot-dip galvannealed steel members, the state of the α-precipitated η phase 111 controlled by the first and second cooling steps collapses, and as a result, the hydrogen desorption properties targeted in this embodiment cannot be achieved. From this perspective, it is important not to perform a heat treatment step after the second cooling step.

[0298] Here, in the cooling process described above, generally known methods such as N2 gas cooling, spray cooling, immersion, etc. can be applied. In addition, the cooling gas can also use a gas with a high heat removal effect such as He gas or hydrogen gas in addition to N2 gas.

[0299] It should be noted that, as a method for measuring the temperature of the coating, for example, a contact thermocouple (K-type) can be used. By installing a contact thermocouple on a steel member that becomes the base material, the average temperature of the coating as a whole can be monitored at all times. In addition, if various speeds and / or thicknesses are controlled mechanically and various operating conditions such as the preheating temperature of the steel member and / or the temperature of the coating bath are unified, the temperature of the coating as a whole at that moment under the manufacturing conditions can be roughly and accurately monitored. Thus, the cooling treatment in the first cooling process and the second cooling process can be precisely controlled. It should be noted that, although not as accurate as the contact type, the surface temperature of the coating can also be measured by a non-contact radiation thermometer.

[0300] In addition, the relationship between the surface temperature of the coating and the average temperature of the entire coating can also be obtained by simulating the heat conduction analysis. Specifically, based on various manufacturing conditions such as the preheating temperature of the steel component and / or the temperature of the coating bath, the speed at which the steel component is lifted from the coating bath, the thickness of the steel component, the thickness of the coating, the heat exchange amount between the coating and the manufacturing equipment, and the heat release of the coating, the surface temperature of the coating and the average temperature of the entire coating can be obtained. Then, using the obtained results, the relationship between the surface temperature of the coating and the average temperature of the entire coating can be obtained. Thus, by measuring the surface temperature of the coating when manufacturing the plated steel component, the average temperature of the entire coating at that moment under the manufacturing conditions can be estimated. As a result, the cooling process in the first cooling process and the second cooling process can be precisely controlled.

[0301] Next, strain is applied to the plated steel member obtained as described above. The method for applying strain is not particularly limited, and may include bending and stretching using a tension leveler, rolling using a skin pass rolling mill, or cold pressing to form the plated steel member into a desired shape.

[0302] Here, in the above-mentioned treatment for imparting strain, it is preferable to impart a strain of 0.2% or more of total elongation to the plated steel member. By imparting a strain corresponding to such a total elongation, the above-mentioned ratio L / L0 can be reliably achieved. Here, the total elongation R TOTAL (Unit: %) is a value determined by the following formula (101). It should be noted that in the following formula (101), L A L is the length in the strip-threading direction of an arbitrary strip-threading direction section X in the plated steel member before the treatment for imparting strain is performed (unit: m), B It is the length in the tape-threading direction of a portion of the plated steel member after the treatment for imparting strain, which portion is from an arbitrary tape-threading direction section X. It is to be noted that the total elongation is more preferably 0.6% or more.

[0303] R TOTAL (%)={(L B -L A ) / L A}×100···(101)

[0304] In addition, the total elongation R TOTAL There is no particular upper limit, but approximately 1.5% is the practical upper limit.

[0305] It should be noted that the above-mentioned treatment for imparting strain can be performed at any time, and can be performed without interruption after the above-mentioned two-stage cooling process, or can be performed after a certain period of time has passed after the completion of the two-stage cooling process. In the plated steel member of this embodiment, by passing through the above-mentioned two-stage cooling process, α-precipitated η phase 111 is generated in the coating layer 103 at a desired average area ratio. Therefore, as long as the treatment for imparting strain is performed at any time after the two-stage cooling process, the above-mentioned ratio L / L0 can be achieved.

[0306] Then, a desired chemical conversion treatment agent is used to form a chemical conversion coating layer 105 on the surface of the plating layer 103. Examples of treatments for forming the chemical conversion coating layer 105 include chromate treatment, phosphate treatment, and chromate-free treatment using a chromate-free chemical conversion treatment agent such as a silicon-based and / or zirconium-based one.

[0307] Chromate treatment includes: electrolytic chromate treatment in which a chromate coating is formed by electrolysis; reactive chromate treatment in which a coating is formed by reaction with the workpiece and then excess treatment liquid is washed away; and coating chromate treatment in which a treatment liquid is applied and dried without washing to form a coating. Any of these chromate treatments can be used.

[0308] Examples of the electrolytic chromate treatment include electrolytic chromate treatment using chromic acid, silica sol, resin (phosphoric acid resin, acrylic resin, vinyl ester resin, vinyl acetate acrylic emulsion, carboxylated styrene butadiene latex, diisopropanolamine-modified epoxy resin, etc.), and hard silica.

[0309] Examples of the phosphate treatment include zinc phosphate treatment, calcium zinc phosphate treatment, and manganese phosphate treatment.

[0310] Chromate-free treatment is particularly environmentally friendly and therefore preferred. Chromate-free treatments include electrolytic treatments that form a chromate-free coating by electrolysis; reactive treatments that form a coating by reacting with the workpiece and then rinsing away excess treatment liquid; and coating treatments that form a coating by applying a treatment liquid and drying it without rinsing. Any of these chromate-free treatments can be used.

[0311] As the chemical conversion treatment agent used for the chromate-free treatment, it is preferable to use the chemical conversion treatment agent containing the silicon compound described above.

[0312] By going through the above-described steps, the first member 10 of the present embodiment can be manufactured.

[0313] It should be noted that, in the above description, strain is applied after forming the plating layer 103, and then a chemical conversion treatment agent is applied. However, after forming the plating layer 103, a chemical conversion treatment coating layer 105 may be formed using a chemical conversion treatment agent, and then the steel member 101 including the chemical conversion treatment coating layer 105 and the plating layer 103 may be strained as described above.

[0314] <About the Manufacturing Method of the Second Member 20>

[0315] The manufacturing method of the second member 20 in this embodiment is not particularly limited, and an appropriate manufacturing method may be appropriately selected according to the blank used as the second member 20 .

[0316] <Regarding Molding Processing of First Member 10 and Second Member 20>

[0317] In the manufacturing method of the adhesively bonded structure 1 of this embodiment, the first component 10 and the second component 20 are formed into the desired shape as needed. Here, there is no particular limitation on the forming method, and a processing method for obtaining the shape of the target formed product can be selected from known metal processing methods. In addition, as needed, part of the forming process and the adhesive bonding process described later can also be carried out simultaneously.

[0318] <About Adhesive Joining Method>

[0319] When the manufactured first component 10 and the second component 20 are bonded together using a prescribed adhesive, first, the desired adhesive is arranged on the portion to be bonded (for example, a flange portion, etc.) of the obtained first component 10 and the second component 20 to form a bonding area. Thereafter, after the first component 10 and the second component 20 are stacked with the aid of the bonding area, a heat treatment is performed to cure the adhesive. Here, there is no particular limitation on the method of configuring the desired adhesive, as long as the desired adhesive is applied or the desired adhesive resin sheet is configured. Thus, the bonding structure 1 of the present embodiment in which the first component 10 and the second component 20 are bonded together with the aid of the adhesive layer 30 can be obtained.

[0320] When various fiber reinforced plastics or the like are used as the second member 20 , the adhesively bonded structure 1 can be obtained by performing warm molding while laminating the first member 10 and the fiber reinforced plastic or the like as the second member 20 with an adhesive.

[0321] An example of the method for producing the adhesively bonded structure according to the present embodiment has been specifically described above.

[0322] Example

[0323] The adhesive bonded structure of the present invention will be described in detail below with reference to Examples and Comparative Examples. It should be noted that the Examples shown below are merely examples of the adhesive bonded structure of the present invention, and the adhesive bonded structure of the present invention is not limited to the examples shown below.

[0324] <Manufacturing of the First Member>

[0325] [Manufacturing of Plated Steel Sheets]

[0326] Hereinafter, plated steel sheets are used as an example of plated steel members. Plated base sheets are cold-rolled steel sheets a to e (all manufactured by Nippon Steel Corporation) each with a thickness of 1.6 mm. The chemical composition of each cold-rolled steel sheet is as follows, with the remainder being Fe and impurities.

[0327] Cold rolled steel sheet a: 0.04 mass% C-0.40 mass% Si-2.20 mass% Mn

[0328] b: 0.09 mass% C-0.40 mass% Si-2.20 mass% Mn

[0329] c: 0.20 mass% C-0.80 mass% Si-2.20 mass% Mn

[0330] d: 0.25 mass% C-0.40 mass% Si-2.40 mass% Mn

[0331] e: 0.35 mass% C-0.70 mass% Si-2.40 mass% Mn

[0332] For each of the cold-rolled steel sheets a to e, JIS 13B test pieces were collected from arbitrary locations on the cold-rolled steel sheets in accordance with JIS Z 2241:2011, and the tensile strength was measured using a commercially available tensile testing machine. The results showed that the tensile strengths of the cold-rolled steel sheets a to e were 590 MPa (cold-rolled steel sheet a), 980 MPa (cold-rolled steel sheet b), 1180 MPa (cold-rolled steel sheet c), 1470 MPa (cold-rolled steel sheet d), and 2500 MPa (cold-rolled steel sheet e), respectively. It should be noted that when samples were collected from the manufactured adhesively bonded structure using the method described above and test pieces were collected from the samples, it is believed that a heating process for curing the adhesive was performed during the manufacture of the adhesively bonded structure. Therefore, in the samples of the steel components collected from the adhesively bonded structure, the steel components may have been heat-cured by the heating process for curing the adhesive, and may have achieved a strength higher than the tensile strength shown on the steel sheets before the adhesively bonded structure was manufactured. However, it is estimated that the tensile strength of the sample collected from the produced adhesively bonded structure is substantially the same as the tensile strength when the test piece is collected from the above-mentioned cold-rolled steel sheet.

[0333] The plated sheets were cut into 100 mm x 200 mm pieces and then plated using our intermittent hot-dip testing equipment. Multiple sheets of plated steel having the coating composition shown in Table 1 were produced for each level. The sheet temperature was measured using a thermocouple spot-welded to the center of the plated sheets. Prior to immersion in the plating bath, the surface of the plated sheets was subjected to a heat reduction treatment at 800°C in an N2-5% H2 atmosphere in a furnace with an oxygen concentration of less than 20 ppm. Following the heat reduction treatment, the sheets were air-cooled with N2 gas. Once the sheet temperature reached the bath temperature + 20°C, the sheets were immersed in the plating bath at the bath temperature shown in Table 1 for approximately 3 seconds.

[0334] After immersion in the coating bath, the steel sheet was pulled out at a speed of 20-200 mm / s. During removal, N2 wiping gas was used to control the coating deposition. After removal from the coating bath, the steel sheet was cooled from the coating bath temperature to room temperature under the conditions shown in Table 1.

[0335] It should be noted that samples were cut into 30 mm x 30 mm sections from each plated steel sheet and their surfaces were observed using a SEM according to the method described above, and the average area ratio of the α-precipitated η phase was calculated. The samples observed under SEM were then immersed in a 10% aqueous HCl solution containing an inhibitor. The coating was then pickled and stripped, and the composition of the coating was determined by ICP analysis of the elements dissolved in the aqueous solution. It is expected that similar results would be obtained when samples were collected from manufactured adhesively bonded structures and analyzed using the same method as described above.

[0336] The obtained samples of the respective plated steel sheets were rolled using a skin pass rolling mill to obtain the total elongation shown in Table 1 below, thereby imparting strain to the plated layer.

[0337] [Formation of Chemical Conversion Treatment Film Layer]

[0338] In order to form the chemical conversion coating layer, the following six chemical conversion agents were prepared.

[0339] (A1) As a chemical conversion treatment agent A1, a water-dispersible emulsion-type polyurethane resin SF-150 manufactured by Daiichi Kogyo Co., Ltd. and 3-glycidoxypropyltriethoxysilane were mixed at a solid content volume ratio of 3:2.

[0340] (A2) As a chemical conversion treatment agent A2, a water-dispersible emulsion-type polyurethane resin SF-150 manufactured by Daiichi Kogyo Co., Ltd. and 3-glycidoxypropyltriethoxysilane were mixed at a solid content volume ratio of 5:1.

[0341] (A3) As a chemical conversion treatment agent A3, a water-dispersible emulsion-type polyurethane resin SF-150 manufactured by Daiichi Kogyo Co., Ltd. and 3-glycidoxypropyltriethoxysilane were mixed at a solid content volume ratio of 1:5.

[0342] (A4) A chemical conversion treatment agent A4 was prepared by mixing a water-dispersible emulsion-type polyurethane resin SF-150 manufactured by Daiichi Kogyo Co., Ltd. and 3-mercaptopropyltrimethoxysilane at a solid content volume ratio of 1:5.

[0343] (B) A polyester resin VYLON GK140 manufactured by Toyobo Co., Ltd. was dissolved in cyclohexanone in a solvent, and imino-type melamine Cymel 325 manufactured by Cytec Industries, Japan was mixed so as to have a solid content volume ratio of 5:1 relative to the resin. A curing catalyst (Catalyst 296-9: Cytec Industries, Japan) was added to adjust the resin solution to 0.1% by volume relative to the resin solid content to prepare a chemical conversion treatment agent B.

[0344] (C) A chemical conversion treatment agent C using only an aqueous solution of 3-glycidoxypropyltriethoxysilane was prepared.

[0345] The chemical conversion agent was applied to a plated steel sheet to a dried film thickness as shown in Table 1 below, and dried and sintered in an induction heating furnace at a maximum plate temperature (PMT) of 150° C. to form a coating.

[0346] <Preparation of Second Component>

[0347] For each level shown in Table 1 below, the same blank as that for the first component manufactured as described above was used as the blank for the second component. In Table 1 below, for levels where the same blank as that for the first component was used as the blank for the second component, the "Second Component" column is marked as "Same as left."

[0348] It should be noted that for some of the levels shown in Table 1 below, alloyed hot-dip galvanized steel sheets (GA) with a tensile strength of 980 MPa at a thickness of 1.0 mm or standard A5000 aluminum sheets with a tensile strength of 290 MPa at a thickness of 1.0 mm (both commercially available products) were used. Furthermore, in No. 25 shown in Table 1 below, the first member in No. 21 shown in Table 1 below (i.e., a galvanized steel sheet without a chemical conversion coating layer) was used as the second member.

[0349] <Adhesive Bonding Process>

[0350] By forming the prepared first and second components, a metallic, cap-shaped component with a flange was produced. As an adhesive for bonding the first and second components, a mixture of 5% by mass of 200μm glass beads added to Penguin Cement #1066, an epoxy resin adhesive manufactured by SANSTAR, was prepared. For each first and second component combination shown in Table 1 below, the adhesive was applied to the surface of the first component, and the second component was attached thereto. This adhesive was then cured by placing the components in an atmosphere at 170°C for 30 minutes, resulting in a closed-section structure.

[0351] It should be noted that in the adhesive joint structure No. 7, a structure in which the adhesive-coated portion was also spot-welded was produced. Specifically, a CF-type Cr-Cu electrode with a tip diameter of 5 mm and R40 was used. 0.5 Under the welding conditions of 100 mm (t is the plate thickness [mm]), spot welding was performed at a spot interval of 30 mm. It should be noted that no adhesive was applied to the spot welding planned portion.

[0352] <Electrodeposition Coating of Cap Member>

[0353] To observe the bonding state under a corrosive environment, the hat-shaped component that had undergone the adhesive bonding treatment described above was subjected to Zn phosphate treatment (SD5350 system: a system in accordance with the standards of Nippon Paint Industrial Coding Co., Ltd.), and then was subjected to electrodeposition coating at 20 μm (PN110 Power Nix Gray-: Nippon Paint Industrial Coding Co., Ltd. standards) and sintered at a sintering temperature of 150°C for 20 minutes.

[0354] <Evaluation of Adhesive-Jointed Structures>

[0355] A plurality of samples were prepared by cutting out a portion of the obtained adhesively bonded structure, and microscopic infrared spectroscopy and TOF-SIMS analysis were performed on vertical cross sections near the interface between the first member and the adhesive layer according to the methods described above.

[0356] It should be noted that in the micro-infrared spectroscopy and TOF-SIMS analysis, the coating portion of the vertical cross section near the interface between the first member and the adhesive layer in the obtained adhesively bonded structure was cut with a 5-degree inclination using an inclined cutting device (DN-20S model manufactured by SAICAS, DAIPLA WINTES CO., LTD.) to expand the coating portion. The micro-infrared spectroscopy device used was an IRT-5200 manufactured by JASCO Corporation, and the TOF-SIMS used was a TOF-SIMS TRIFT-V manufactured by ULVAC-PHI Inc.

[0357] Here, in the microscopic infrared spectroscopy analysis, the above-mentioned microscopic infrared spectroscopy analysis device is used for mapping measurement. Based on the attribution of the observed peaks from the resin component in the infrared absorption spectrum of the obtained coating part, it is determined whether it contains one or more of water-based polyurethane resin, epoxy resin, and polyester resin, and whether it contains at least one of Si-C bond, Si-O bond, or Si-OH bond. Specifically, in the obtained infrared absorption spectrum, at 910 cm -1 If a peak is observed near 1550 cm -1 Nearby and 1740cm -1 If a peak is observed near 1720-1740 cm -1 In the following, the case where the compound is determined to contain at least any one of an epoxy group, a carbamate group, or an ester group is marked as A, and the case where the compound is determined not to contain these functional groups is marked as B.

[0358] In addition, in the TOF-SIMS analysis, the above-mentioned device is used to perform argon sputtering while analyzing any point in the portion where the adhesive layer is thinned to about 1 μm from the adhesive layer side toward the metal component side. After sputtering from the surface to a certain depth with an Ar beam, TOF-SIMS measurement is performed. Subsequently, the same sputtering is performed and TOF-SIMS measurement is performed. This operation is repeated to obtain a depth distribution for various elements and bonds. The primary ion species is Au. 3+ The acceleration voltage was 30 kV, the sputtering rate was approximately 80 nm / min (SiO2 conversion), and the measurement area was 50 μm × 50 μm. The presence or absence of a peak representing Si-O-Me bonds was confirmed at the interface between the chemical conversion coating layer (or the adhesive layer if no chemical conversion coating layer was present) and the metal component.

[0359] In Table 1 below, the presence or absence of Si-O-Me bonds and whether the Total Ion correction value exceeds 1.0×10 -3 It should be noted that, below, the compounds with Si-O-Me bonds and Total Ion correction values ​​exceeding 1.0×10 -3 The case with no Si-O-Me bond or a Total Ion correction value of 1.0×10 -3 The following situation is recorded as B.

[0360] A sample was prepared by cutting out a portion of the obtained adhesively bonded structure. A vertical cross section near the interface between the first member and the adhesive layer was observed using SEM (SU3800 manufactured by Hitachi Ltd.) according to the method described above, and the bonding length ratio L / L0 was calculated.

[0361] <Adhesion Durability Evaluation>

[0362] The bonding durability of the adhesively bonded structures obtained in each example was evaluated.

[0363] First, for each adhesive bonded structure, the torsional rigidity is measured and calculated using a torsion testing machine. Specifically, the two ends of each adhesive bonded structure are fixed with a jig, and only one end is rotated about the central axis of the adhesive bonded structure, thereby applying torsional deformation to the adhesive bonded structure. The torsional angle and torsional moment at this time are measured, and the torsional rigidity of each adhesive bonded structure is calculated based on the relationship between the torsional angle and the torsional moment within the elastic deformation range. Specifically, the initial slope of the torsional angle-torsional moment graph is used as the relationship between the torsional angle and the torsional moment within the elastic deformation range.

[0364] Next, a salt spray test was conducted in accordance with JIS Z2371:2015. Each adhesively bonded structure was allowed to stand for 4800 hours to accelerate degradation of the adhesive layer and the adhesive layer / chemical conversion coating layer interface. After standing in the salt spray tester, the torsional rigidity of each adhesively bonded structure was measured and calculated using a torsion tester. The torsional rigidity of each adhesively bonded structure was then compared with that of each adhesively bonded structure that had not undergone the degradation test. The reduction in torsional rigidity due to degradation was calculated and used as an evaluation indicator for joint durability.

[0365] The reduction rate of the flexural strength after the salt spray test relative to the flexural strength before the salt spray test was calculated and evaluated according to the following evaluation criteria: A score of C or higher was considered acceptable.

[0366] Rating AAA: Reduction rate less than 10%

[0367] AA: Reduction rate is 10% or more and less than 20%

[0368] A: The reduction rate is 20% or more and less than 30%

[0369] B: Reduction rate is 30% or more and less than 40%

[0370] C: Reduction rate is 40% or more and less than 50%

[0371] D: Reduction rate is more than 50%

[0372] <Red Rust Resistance Evaluation>

[0373] Red rust resistance was evaluated as follows.

[0374] Samples measuring 50 x 100 mm, cut from the first member at each level shown in Table 1 below, were treated with zinc phosphate (SD5350 system: a system manufactured by Nippon Paint Industrial Coding Co., Ltd.). They were then electroplated to a thickness of 20 μm (PN110 Power Nix Gray: manufactured by Nippon Paint Industrial Coding Co., Ltd.). After sintering at 150°C for 20 minutes, a cut was introduced into the center of the sample, reaching the ferrite. The samples were then subjected to a combined cycle corrosion test in accordance with JASO (M609-91) to evaluate the number of cycles required for red rust to develop.

[0375] The evaluation criteria are as follows: A score of A or higher is considered a pass.

[0376] Rating AA: More than 60 cycles

[0377] A: More than 30 cycles and less than 60 cycles

[0378] B: Less than 30 cycles

[0379] The obtained results are summarized in Table 2 below.

[0380] [Table 1]

[0381]

[0382] [Table 2]

[0383] Table 2

[0384]

[0385] As can be seen from Table 2, the adhesively bonded structures corresponding to the examples of the present invention exhibited excellent adhesive durability, whereas the adhesively bonded structures corresponding to the comparative examples of the present invention exhibited poor adhesive durability.

[0386] While preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these embodiments. It is obvious that anyone with ordinary knowledge in the technical field to which the present invention pertains would be able to conceive of various variations and modifications within the scope of the technical concept set forth in the claims, and such variations and modifications are naturally understood to fall within the technical scope of the present invention.

[0387] The embodiments disclosed herein are illustrative and non-restrictive in all respects. The above-mentioned embodiments may be omitted, replaced, or changed in various ways without departing from the appended claims, the configurations belonging to the technical scope of the present invention described later, and the gist thereof. For example, the constituent elements of the above-mentioned embodiments may be arbitrarily combined within the scope that does not impair their effects. In addition, according to this arbitrary combination, it is of course possible to obtain the effects and effects of the various constituent elements involved in the combination, and according to the description of this specification, it is possible to obtain other effects and other effects that are clear to those skilled in the art.

[0388] In addition, the effects described in this specification are merely illustrative or exemplary and are not limiting. That is, the technology involved in the present invention can also produce other effects that are obvious to those skilled in the art based on the description of this specification in addition to or instead of the above effects.

[0389] It should be noted that the following configurations also fall within the technical scope of the present invention. (1)

[0391] An adhesively bonded structure comprising a first member, a second member, and an adhesive layer for bonding the first member to the second member, wherein the first member is a plated steel member comprising a steel member and a plated layer on the steel member, wherein the plated layer has the following chemical composition: containing, by mass%, 0.50 to 5.00% Al, 0.50 to 3.00% Mg, and 0.01 to 15.00% Fe, and optionally containing one or more selected from the group consisting of the following element group A, element group B, element group C, element group D, element group E, element group F, and element group G, and the remainder The amount is Zn and impurities, and in the surface structure when looking down at the surface of the aforementioned coating, the average area ratio of the α precipitated η phase in the metallographic structure obtained by precipitation of the α phase in the η parent phase is 5 to 95%, and the cross-section of the aforementioned adhesive joint structure cut along the stacking direction of the aforementioned first component, the aforementioned second component and the aforementioned adhesive layer is observed by an electron microscope. The sum of the lengths of the contact between the aforementioned coating or the aforementioned steel component and the aforementioned adhesive layer, that is, the bonding length, is recorded as L, and the length of the observation field in the direction perpendicular to the surface normal direction of the aforementioned steel component is recorded as L0, and the ratio L / L0 is greater than 1.10.

[0392] [Element Group A]: One or two elements selected from the group consisting of Si: more than 0% and 2.00% or less and Ca: more than 0% and 2.00% or less

[0393] [Element Group B]: One or more elements selected from the group consisting of Sb: more than 0% and 0.5000% or less, Pb: more than 0% and 0.50% or less, and Sr: more than 0% and 0.50% or less

[0394] [Element Group C]: One or more elements selected from the group consisting of Cu: more than 0% and 1.00% or less, Ti: more than 0% and 1.00% or less, Cr: more than 0% and 1.00% or less, Nb: more than 0% and 1.00% or less, Ni: more than 0% and 1.00% or less, Mn: more than 0% and 1.00% or less, Mo: more than 0% and 1.00% or less, Co: more than 0% and 1.0000% or less, and V: more than 0% and 1.0000% or less.

[0395] [Element Group D]: One or more elements selected from the group consisting of Sn: more than 0% and 1.00% or less, In: more than 0% and 1.0000% or less, and Bi: more than 0% and 1.0000% or less

[0396] [Element Group E]: One or more elements selected from the group consisting of Zr: more than 0% and 1.00% or less, Ag: more than 0% and 1.00% or less, and Li: more than 0% and 1.00% or less

[0397] [Element Group F]: One or more elements selected from the group consisting of La: more than 0% and 0.50% or less, Ce: more than 0% and 0.50% or less, and Y: more than 0% and 0.50% or less

[0398] [Element Group G]: B: more than 0% and 0.50% or less (2)

[0400] The adhesively bonded structure according to (1) has a chemical composition containing the element group A. (3)

[0402] The adhesively bonded structure according to (1) has a chemical composition containing the element group B. (4)

[0404] The adhesively bonded structure according to (1) has a chemical composition containing the element group C. (5)

[0406] The adhesively bonded structure according to (1) has a chemical composition containing the element group D. (6)

[0408] The adhesively bonded structure according to (1) has a chemical composition containing the element group E. (7)

[0410] The adhesively bonded structure according to (1) has a chemical composition containing the element group F. (8)

[0412] The adhesively bonded structure according to (1) has a chemical composition containing the element group G. (9)

[0414] The adhesively bonded structure according to any one of (1) to (8), wherein the plating layer contains 1.00 to 5.00 mass % of Al and 1.00 to 3.00 mass % of Mg. (10)

[0416] An adhesively bonded structure according to any one of (1) to (9), wherein the first component further has a chemical conversion coating layer on the coating layer, and in the presence of the chemical conversion coating layer, the bonding length L is the sum of the contact lengths of the chemical conversion coating layer, the coating layer or the steel component and the adhesive layer. (11)

[0418] The adhesively bonded structure according to (10), wherein the chemical conversion coating layer contains at least one of: a carbamate group, an epoxy group, or an ester group; and a silicon compound having at least one of a Si-O bond and a Si-OH bond, and when the chemical conversion coating layer is subjected to Ar sputtering from the adhesive layer side toward the steel member side in a manner including any portion of the interface between the plating layer and the chemical conversion coating layer, a peak corresponding to a Si-O-Me bond is observed when analyzed by time-of-flight secondary ion mass spectrometry, wherein the Si-O-Me bond is a bond with a metal element Me (Me: F, Zn, Al, Mg) derived from the steel member or the plating layer, and the value obtained by dividing the count of the peak corresponding to the Si-O-Me bond by the total value of all secondary ion counts detected in the mass scan range of m / z = 0 to 300 is 1.0×10 -3 above. (12)

[0420] The adhesively bonded structure according to any one of (1) to (11), wherein the steel member has a tensile strength of 980 MPa or more. (13)

[0422] The adhesively bonded structure according to any one of (1) to (12), wherein the steel member has a tensile strength of 1180 MPa or more. (14)

[0424] The adhesively bonded structure according to any one of (1) to (13), wherein the ratio L / L0 is 1.30 or more. (15)

[0426] The adhesively bonded structure according to any one of (1) to (14), wherein the ratio L / L0 is 1.60 or more.

[0427] Description of Reference Numerals

[0428] 1. Bonding structures

[0429] 10 First Component

[0430] 20 Second component

[0431] 30 Adhesive layer

[0432] 101 Steel Structures

[0433] 103 coating

[0434] 105 Chemical conversion treatment coating layer

[0435] 111 α precipitation η phase

[0436] 113 Hard tissue

[0437] 121 α phase

[0438] 123 η-Zn phase

Claims

1. An adhesively bonded structure comprising a first member, a second member, and an adhesive layer for bonding the first member and the second member. The first member is a plated steel member having a steel member and a plated layer on the steel member, The coating has the following chemical composition: Contains by mass% Al：0.50～5.00％ Mg: 0.50~3.00% Fe: 0.01~15.00%, further optionally containing one or more elements selected from the group consisting of the following element group A, element group B, element group C, element group D, element group E, element group F, and element group G, The balance is Zn and impurities, In the surface structure of the plated layer when viewed from above, the average area ratio of the α-precipitated η phase in the metallographic structure obtained by precipitation of the α phase in the η matrix phase is 5 to 95%. When observing a cross section of the adhesively bonded structure cut along the lamination direction of the first member, the second member, and the adhesive layer using an electron microscope, where the total length of contact between the plating layer or the steel member and the adhesive layer, i.e., the bonding length, is represented by L, and the length of the observation field in a direction perpendicular to the surface normal direction of the steel member is represented by L0, the ratio L / L0 is 1.10 or greater. [Element Group A]: one or two elements selected from the group consisting of Si: more than 0% and 2.00% or less and Ca: more than 0% and 2.00% or less; [Element Group B]: one or more elements selected from the group consisting of Sb: more than 0% and 0.5000% or less, Pb: more than 0% and 0.50% or less, and Sr: more than 0% and 0.50% or less; [Element Group C]: one or more elements selected from the group consisting of Cu: more than 0% and 1.00% or less, Ti: more than 0% and 1.00% or less, Cr: more than 0% and 1.00% or less, Nb: more than 0% and 1.00% or less, Ni: more than 0% and 1.00% or less, Mn: more than 0% and 1.00% or less, Mo: more than 0% and 1.00% or less, Co: more than 0% and 1.0000% or less, and V: more than 0% and 1.0000% or less; [Element Group D]: one or more elements selected from the group consisting of Sn: more than 0% and 1.00% or less, In: more than 0% and 1.0000% or less, and Bi: more than 0% and 1.0000% or less; [Element Group E]: one or more elements selected from the group consisting of Zr: more than 0% and 1.00% or less, Ag: more than 0% and 1.00% or less, and Li: more than 0% and 1.00% or less; [Element Group F]: one or more elements selected from the group consisting of La: more than 0% and 0.50% or less, Ce: more than 0% and 0.50% or less, and Y: more than 0% and 0.50% or less; [Element Group G]: B: more than 0% and 0.50% or less. 2 . The adhesively bonded structure according to claim 1 , having a chemical composition containing the element group A. The adhesively bonded structure according to claim 1 , having a chemical composition containing the element group B. The adhesively bonded structure according to claim 1 , having a chemical composition containing the element group C. The adhesively bonded structure according to claim 1 , having a chemical composition containing the element group D. The adhesively bonded structure according to claim 1 , having a chemical composition containing the element group E. The adhesively bonded structure according to claim 1 , having a chemical composition containing the element group F. The adhesively bonded structure according to claim 1 , having a chemical composition containing the element group G.

9. The adhesively bonded structure according to any one of claims 1 to 8, wherein The plating layer contains 1.00 to 5.00 mass % of Al and 1.00 to 3.00 mass % of Mg.

10. The adhesively bonded structure according to any one of claims 1 to 8, wherein The first component further has a chemical conversion coating layer on the plating layer, When the chemical conversion coating layer is present, the bonding length L is the total length of contact between the chemical conversion coating layer, the plating layer, or the steel member and the adhesive layer.

11. The adhesively bonded structure according to claim 9, wherein: The first component further has a chemical conversion coating layer on the plating layer, When the chemical conversion coating layer is present, the bonding length L is the total length of contact between the chemical conversion coating layer, the plating layer, or the steel member and the adhesive layer.

12. The adhesively bonded structure according to claim 10, wherein: The chemical conversion coating layer contains at least one of a carbamate group, an epoxy group, or an ester group; and a silicon compound having at least one of a Si-O bond and a Si-OH bond. When the chemical conversion coating layer is subjected to Ar sputtering from the adhesive layer side toward the steel member side in a manner including any portion of the interface between the coating layer and the chemical conversion coating layer, and analyzed by time-of-flight secondary ion mass spectrometry, a peak corresponding to a Si-O-Me bond is observed, wherein the Si-O-Me bond is a bond with a metal element Me derived from the steel member or the coating layer, Me: F, Zn, Al, Mg, and the value obtained by dividing the count of the peak corresponding to the Si-O-Me bond by the total value of all secondary ion counts detected in the mass scan range of m / z = 0 to 300 is 1.0×10 -3 above.

13. The adhesively bonded structure according to claim 11, wherein: The chemical conversion coating layer contains at least one of a carbamate group, an epoxy group, or an ester group; and a silicon compound having at least one of a Si-O bond and a Si-OH bond. When the chemical conversion coating layer is subjected to Ar sputtering from the adhesive layer side toward the steel member side in a manner including any portion of the interface between the coating and the chemical conversion coating, and analyzed by time-of-flight secondary ion mass spectrometry, a peak corresponding to a Si-O-Me bond is observed, wherein the Si-O-Me bond is a bond with a metal element Me derived from the steel member or the coating, Me: F, Zn, Al, Mg, and the value obtained by dividing the count of the peak corresponding to the Si-O-Me bond by the total value of all secondary ion counts detected in the mass scan range of m / z = 0 to 300 is 1.0×10 -3 above.

14. The adhesively bonded structure according to claim 1, wherein The tensile strength of the steel member is greater than 980 MPa.

15. The adhesively bonded structure according to claim 1, wherein The tensile strength of the steel member is greater than 1180 MPa.

16. The adhesively bonded structure according to claim 1, wherein The ratio L / L0 is 1.30 or more.

17. The adhesively bonded structure according to claim 1, wherein: The ratio L / L0 is 1.60 or more.

Images