Joined body

Abstract

This joined body (1) includes: a first joining material (100) including a core material (110) having one surface (111) and a sacrificial anti-corrosion layer (120) covering the one surface of the core material; a second joining material (200) joined to the first joining material; and an adhesive (300) for joining the first joining material and the second joining material. The first joining material has dividing parts (101, 102, 116) for dividing a preferential sacrificial part (121) that will corrode in the sacrificial anti-corrosion layer and an adhesive part (123) to which the adhesive is fixed in the first joining material.

Description

zygote CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2024-34761 filed on March 7, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to conjugates.

[0003] Conventionally, a metal material comprising a base material, a sacrificial metal layer adhered to the surface of the base material via an insulating adhesive layer, and a protective layer formed on the surface of the sacrificial metal layer has been proposed, for example, in Patent Document 1.

[0004] JP 2008-001944 A

[0005] The inventors have investigated a structure in which a sacrificial protection layer, which is more susceptible to corrosion than the substrate, is provided on a substrate and another bonding material is bonded to the sacrificial protection layer. As a result, they have found that corrosion products are generated when part of the sacrificial protection layer corrodes, and that the corrosion products grow within the sacrificial protection layer.

[0006] Furthermore, it was found that as the volume of the corrosion products increases, the stress of the corrosion products concentrates at the bonded interface between the sacrificial protection layer and another bonded material, pushing up the bonded portion between the sacrificial protection layer and the other bonded material. This causes a gap to form between the sacrificial protection layer and the other bonded material, accelerating crevice corrosion. Alternatively, the application of an external force to the bonded body generates peeling stress at the bonded portion. This causes the sacrificial protection layer to peel off from the other bonded material early.

[0007] In view of the above, the present disclosure aims to provide a joined body that can improve corrosion life by maintaining joint strength even if corrosion of the sacrificial anticorrosion layer progresses.

[0008] According to one aspect of the present disclosure, a joint includes a first joining material including a core material having one surface and a sacrificial anticorrosion layer covering one surface of the core material and having a lower potential than the core material, a second joining material joined to the first joining material, and an adhesive joining the first joining material and the second joining material.

[0009] The first bonding material has a separating portion that separates the preferential sacrificial portion of the sacrificial anticorrosion layer that will corrode and the adhesive portion of the first bonding material where the adhesive is fixed.

[0010] According to this, the priority sacrificial portion of the sacrificial protection layer and the adhesive portion of the first bonding material are separated by the separating portion. Therefore, even if corrosion progresses in the priority sacrificial portion, the corrosion products cannot progress to the adhesive portion due to the separating portion. Therefore, the stress of the corrosion products is not concentrated in the adhesive portion, and premature peeling does not occur between the adhesive portion and the second bonding material. Therefore, even if corrosion progresses in the priority sacrificial portion of the sacrificial protection layer, the bonding strength between the first bonding material and the second bonding material can be maintained, and the corrosion life of the bonded structure can be improved.

[0011] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. 1 is a plan view of a bonded body according to the first embodiment, FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, FIG. 3 is a plan view of a bonded body showing the progression of corrosion products, FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3, FIG. 5 is a plan view of a comparative example of a bonded body according to the first embodiment, FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5, FIG. 7 is a cross-sectional view of another example of a bonded body according to the first embodiment, FIG. 8 is a cross-sectional view of another example of a bonded body according to the first embodiment, FIG. 9 is a cross-sectional view of another example of a bonded body according to the first embodiment, FIG. 10 is a cross-sectional view of another example of a bonded body according to the first embodiment, FIG. 11 is a cross-sectional view of another example of a bonded body according to the first embodiment, FIG. 12 is a cross-sectional view of another example of a bonded body according to the first embodiment, FIG. 13 is a cross-sectional view of another example of a bonded body according to the first embodiment, FIG. 14 is a cross-sectional view of another example of a bonded body according to the first embodiment, and FIG. 15 is a cross-sectional view of a bonded body according to the second embodiment.

[0012] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicated explanations may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0013] First Embodiment A bonded body according to this embodiment is formed by bonding a first bonding material and a second bonding material together. The bonded body is used, for example, to bond burred portions through which cooling water passes in a heat exchanger.

[0014] Fig. 1 is a plan view of a bonded structure 1. Fig. 2 is a cross-sectional view of the bonded structure 1 shown in Fig. 1. As shown in Figs. 1 and 2, the bonded structure 1 includes a first bonding material 100, a second bonding material 200, and an adhesive 300.

[0015] The first bonding material 100 includes a core material 110 and a sacrificial anticorrosion layer 120. The core material 110 is, for example, a plate-shaped component having one surface 111 and another surface 112 opposite to the one surface 111. The core material 110 is made of, for example, a metal material such as pure aluminum or an aluminum alloy.

[0016] The sacrificial protection layer 120 covers one surface 111 of the core material 110. In other words, the first bonding material 100 is a clad material in which one surface 111 of the core material 110 is covered with the sacrificial protection layer 120. The sacrificial protection layer 120 has a lower potential than the core material 110, that is, a lower potential than the core material 110. As a result, the sacrificial protection layer 120 corrodes preferentially to the core material 110, thereby preventing corrosion of the core material 110. The sacrificial protection layer 120 is made of, for example, an aluminum alloy such as an Al-Zn alloy.

[0017] The thickness of the sacrificial protection layer 120 is, for example, several tens of μm to several hundreds of μm. Since the sacrificial protection layer 120 is clad on one surface 111 of the core material 110, the thickness of the sacrificial protection layer 120 is uniform. Of course, there will be some difference in thickness depending on the position, but it is sufficient that the thickness of the sacrificial protection layer 120 is uniform. In other words, the thickness of the sacrificial protection layer 120 does not have to be completely uniform.

[0018] The second joining material 200 is a material to be joined to the first joining material 100. In this embodiment, the second joining material 200 is a metal plate such as pure aluminum or an aluminum alloy.

[0019] The core material 110 of the first bonding material 100 and the second bonding material 200 are not limited to aluminum-based metal materials, and may be made of other metal materials such as zinc-plated steel sheets. The shape of the second bonding material 200 is not limited to a plate shape, and various shapes such as a block or a pipe can be adopted. Of course, the second bonding material 200 may be a clad material consisting of a core material and a sacrificial anticorrosion layer, similar to the first bonding material 100.

[0020] The adhesive 300 is a component that bonds the first bonding material 100 and the second bonding material 200. The adhesive 300 is made of, for example, an epoxy-based resin. The adhesive 300 bonds the first bonding material 100 and the second bonding material 200 without heating, i.e., without causing solid-state diffusion of elements. Note that the adhesive 300 may be made of a silicone-based or acrylic-based resin.

[0021] Next, a specific structure of the joined body 1 will be described. In the above configuration, the first joining material 100 has a protrusion 101. As shown in Fig. 2, the protrusion 101 is formed by half-punching from the sacrificial protection layer 120 side to the core material 110 side in a state where the sacrificial protection layer 120 is formed on one surface 111 of the core material 110.

[0022] 1, the protrusion 101 is continuously formed on the core material 110 from one end 113 to the other end 114 of the core material 110 along one direction parallel to one surface 111 of the core material 110. Half-blanking is a type of press working. Half-blanking is a process in which a portion of the base material is deformed rather than being completely punched out.

[0023] 2, in a vertical direction perpendicular to one surface 111 of the core material 110, the protrusion 101 has a groove structure in which a part of the core material 110 is sunken, and also has a step structure. In this embodiment, the protrusion 101 is a step portion that forms two steps.

[0024] As described above, by subjecting a portion of the first bonding material 100 to half-punching, the sacrificial layer 120 is divided into a priority sacrificial portion 121 and a non-sacrificial portion 122. That is, the priority sacrificial portion 121 and the non-sacrificial portion 122 are completely separated. That is, the priority sacrificial portion 121 and the non-sacrificial portion 122 are not connected to each other.

[0025] The priority sacrificial portion 121 is a portion of the sacrificial protection layer 120 that will corrode. The priority sacrificial portion 121 is a portion of the joined body 1 that will be exposed to a corrosive solution. The non-sacrificial portion 122 is a portion of the sacrificial protection layer 120 that corresponds to the adhesive portion 123. The adhesive portion 123 is a portion of the first joining material 100 where the adhesive 300 is fixed. The adhesive portion 123 is the entire non-sacrificial portion 122.

[0026] The adhesive 300 bonds the non-sacrificial portion 122 of the sacrificial protection layer 120 to the second bonding material 200. Here, if a direction parallel to one surface 111 of the core material 110 and perpendicular to the one direction and the perpendicular direction is defined as the other direction, the end portion 210 of the second bonding material 200 on the preferential sacrificial portion 121 side in the other direction is fixed to the bonding portion 123 of the first bonding material 100 by the adhesive 300.

[0027] In this embodiment, the adhesive 300 is provided over the entire non-sacrificial portion 122. That is, the adhesive 300 fills the entire groove portion formed by the protrusion 101. Note that in FIG. 2 , the adhesive 300 is also in contact with a portion of the first surface 121A of the priority sacrificial portion 121 on the non-sacrificial portion 122 side, but this is only a portion of the adhesive 300 that has overflowed from between the first bonding material 100 and the second bonding material 200, and this amount does not contribute to the adhesive strength. That is, most of the adhesive 300 is provided in the non-sacrificial portion 122 of the sacrificial corrosion protection layer 120, and the non-sacrificial portion 122 corresponds to the adhesive portion 123 to the second bonding material 200.

[0028] In this embodiment, at least the portion of the sacrificial protection layer 120 that corresponds to the protrusion 101 is the non-sacrificial portion 122. In addition, the portion of the sacrificial protection layer 120 on the opposite side of the protrusion 101 from the priority sacrificial portion 121 is also the non-sacrificial portion 122. It can be said that the step on the priority sacrificial portion 121 side of the two steps of the protrusion 101 separates the priority sacrificial portion 121 from the non-sacrificial portion 122.

[0029] The height of the protrusion 101 formed by half-blanking, i.e., the size of the step, is adjusted as follows: That is, the difference in the vertical direction between the position of the first surface 121A of the priority sacrificial portion 121 and the position of the second surface 122A of the portion of the non-sacrificial portion 122 corresponding to the protrusion 101 is larger than the thickness of the priority sacrificial portion 121.

[0030] In other words, the vertical distance from the first surface 121A to the second surface 122A is greater than the thickness of the priority sacrificial portion 121. In other words, the size of the step formed by the protrusion 101 is greater than the thickness of the priority sacrificial portion 121. Due to the height of the protrusion 101, the side surface 115 of the half-punched portion of the core material 110 is exposed from the sacrificial protection layer 120. The sacrificial protection layer 120 is not present on the side surface 115 of the core material 110 that forms the protrusion 101. Therefore, the protrusion 101 can be said to be a step formed in the core material 110, as well as a dividing portion that divides the priority sacrificial portion 121 of the sacrificial protection layer 120 and the non-sacrificial portion 122 of the sacrificial protection layer 120 that corresponds to the adhesive portion 123 (protrusion 101).

[0031] In this embodiment, the first surface 121A of the priority sacrificial portion 121 and the surface of the portion of the non-sacrificial portion 122 that does not correspond to the protrusion 101 have the same vertical height. However, for example, the first surface 121A of the priority sacrificial portion 121 may have a higher vertical height than the surface of the portion of the non-sacrificial portion 122 that does not correspond to the protrusion 101. Alternatively, the first surface 121A of the priority sacrificial portion 121 may have a lower vertical height than the surface of the portion of the non-sacrificial portion 122 that does not correspond to the protrusion 101.

[0032] Next, a method for manufacturing the bonded body 1 will be described. First, the first bonding material 100 and the second bonding material 200, each having the protrusion 101 formed thereon, are prepared. Next, the adhesive 300 is applied to the portion of the first bonding material 100 corresponding to the adhesive portion 123. Alternatively, the adhesive 300 may be applied to the second bonding material 200. Then, the first bonding material 100 and the second bonding material 200 are brought relatively close to each other in the vertical direction, so that the second bonding material 200 comes into contact with the adhesive 300. Thereafter, the first bonding material 100 and the second bonding material 200 are held in place until the adhesive 300 hardens. In this manner, the bonded body 1 is completed.

[0033] As described above, in this embodiment, the protrusions 101 are provided on the first bonding material 100, so that the sacrificial layer 120 is structured to be fractured into a priority sacrificial portion 121 and a non-sacrificial portion 122. For this reason, as shown by the arrows in Figures 3 and 4 , even if corrosion occurs in the priority sacrificial portion 121 and progresses within the priority sacrificial portion 121, the corrosion products cannot progress beyond the priority sacrificial portion 121. In other words, the presence of the protrusions 101 prevents the corrosion products from progressing to the non-sacrificial portion 122 of the bonding joint 123.

[0034] As a comparative example, a structure in which the protrusion 101 is not provided on the first bonding material 100 is shown in Figures 5 and 6. As shown by the arrows in Figures 5 and 6, corrosion products can progress from end to end in other directions. Therefore, corrosion products generated in the sacrificial protection layer 120 can reach the adhesive joint 123. As a result, stress from the corrosion products is concentrated at the interface between the sacrificial protection layer 120 and the adhesive 300, causing the adhesive 300 to peel off from the sacrificial protection layer 120 early.

[0035] In contrast, in a structure in which the protrusions 101 are provided on the first bonding material 100, the protrusions 101 prevent the corrosion products from progressing to the non-sacrificial portion 122. Therefore, stress from the corrosion products is less likely to concentrate on the adhesive portion 123. Therefore, the adhesive portion 123 of the first bonding material 100 and the second bonding material 200 are less likely to peel off early. Therefore, even if corrosion progresses to the priority sacrificial portion 121 of the sacrificial corrosion protection layer 120, the bonding strength between the first bonding material 100 and the second bonding material 200 can be maintained. Furthermore, the corrosion resistance of the adhesive portion 123 of the first bonding material 100 can be improved, and the corrosion life of the bonded body 1 can be improved.

[0036] Moreover, the protrusions 101 can be provided to the first bonding material 100 when the first bonding material 100 is processed into parts. Therefore, the corrosion resistance of the bonded body 1 can be improved without adding a special material or a special process, that is, without reducing productivity.

[0037] As another example, as shown in FIGS. 7 and 8 , the adhesive 300 does not need to overflow onto the first surface 121A of the priority sacrificial portion 121. For example, as shown in FIG. 7 , the adhesive 300 may be provided over the entire non-sacrificial portion 122 of the sacrificial layer 120. Alternatively, as shown in FIG. 8 , the adhesive 300 may be provided so that a portion of the non-sacrificial portion 122 corresponding to the protrusion 101 is exposed on the priority sacrificial portion 121 side. In the case shown in FIG. 8 , the entire portion of the non-sacrificial portion 122 not corresponding to the protrusion 101 is covered with the adhesive 300, so there is no problem with adhesive strength. Furthermore, even if corrosion occurs in the portion of the non-sacrificial portion 122 corresponding to the protrusion 101, the step of the protrusion 101 prevents the corrosion products from progressing to the portion of the non-sacrificial portion 122 not corresponding to the protrusion 101.

[0038] 9, the protrusion 101 may be formed on the first bonding material 100 by half-punching from the core material 110 side to the sacrificial layer 120 side in a protruding shape, with the sacrificial layer 120 formed on one surface 111 of the core material 110. In this case, as in the cases shown in FIGS. 7 and 8, the adhesive 300 may be provided on the entire non-sacrificial portion 122, or may be provided so that a part of the portion of the non-sacrificial portion 122 corresponding to the protrusion 101 is exposed.

[0039] 10 , the first bonding material 100 may have a stepped portion 102 instead of the protruding portion 101. The stepped portion 102 is a step portion formed by half-punching the sacrificial protection layer 120 formed on one surface 111 of the core material 110 to form at least one stepped step from the sacrificial protection layer 120 side to the core material 110 side. The stepped portion 102 is also a dividing portion that divides the priority sacrificial portion 121 of the sacrificial protection layer 120 from the non-sacrificial portion 122 corresponding to the adhesive portion 123.

[0040] By providing the staircase portion 102 in the first bonding material 100, the sacrificial anticorrosion layer 120 is not present on the side surface 115 of the core material 110 that constitutes the staircase portion 102. The staircase portion 102 is not limited to one step, and may be formed with multiple steps. The adhesive 300 may be in contact with a portion of the first surface 121A of the priority sacrificial portion 121 as shown in FIG. 10 , or may not be in contact with the first surface 121A of the priority sacrificial portion 121 as shown in FIG. 11 .

[0041] 12 , the entire non-sacrificial portion 122 side of the first bonding material 100 may be inclined with respect to the priority sacrificial portion 121 side. Furthermore, on the non-sacrificial portion 122 side of the first bonding material 100, the portion near the staircase portion 102 may be inclined with respect to the priority sacrificial portion 121 side, while the portion away from the staircase portion 102 may not be inclined with respect to the priority sacrificial portion 121.

[0042] The entirety of the first bonding material 100 on the priority sacrificial portion 121 side may be inclined with respect to the non-sacrificial portion 122 side. Furthermore, on the priority sacrificial portion 121 side of the first bonding material 100, the portion near the staircase portion 102 may be inclined with respect to the non-sacrificial portion 122 side, while the portion away from the staircase portion 102 may not be inclined with respect to the non-sacrificial portion 122.

[0043] The entire first bonding material 100 on the priority sacrificial portion 121 side and the entire non-sacrificial portion 122 side may be inclined in the other direction. Of course, only the portion near the staircase portion 102 may be inclined in the other direction.

[0044] 13, the stepped portion 102 may be formed by half-punching at least one stepped step from the core material 110 side to the sacrificial layer 120 side, with the sacrificial layer 120 formed on one surface 111 of the core material 110. The stepped portion 102 may be formed in multiple steps. The adhesive 300 is provided so as to contact a portion of the first surface 121A of the priority sacrificial portion 121. Of course, as in the case shown in FIG. 11, the adhesive 300 does not necessarily have to contact the first surface 121A of the priority sacrificial portion 121. Note that in FIG. 13, as in FIG. 12, the non-sacrificial portion 122 side or the priority sacrificial portion 121 side may be inclined.

[0045] 14 , the first bonding material 100 may have a recess 104 instead of the protrusion 101 and the step portion 102. The recess 104 is a groove formed so as to penetrate the sacrificial protection layer 120 from the sacrificial protection layer 120 side to the core material 110 side and reach the core material 110, in a state in which the sacrificial protection layer 120 is formed on one surface 111 of the core material 110.

[0046] The recess 104 is formed continuously in one direction from one end 113 to the other end 114 of the core material. The recess 104 is formed in the first bonding material 100 by, for example, cutting or etching. The recess 104 divides the sacrificial anticorrosion layer 120 into a priority sacrificial portion 121 side and a non-sacrificial portion 122 side. Therefore, even if corrosion progresses in the priority sacrificial portion 121, the progression of corrosion toward the non-sacrificial portion 122 side can be suppressed.

[0047] Alternatively, a core material 110 having recesses 104 formed therein may be prepared, and a mask may be formed to prevent the sacrificial protection layer 120 from being formed in the recesses 104, followed by forming the preferential sacrificial portion 121 and the non-sacrificial portion 122 of the sacrificial protection layer 120 on one surface 111 of the core material 110. In this case as well, it can be said that the recesses 104 are formed so as to penetrate the sacrificial protection layer 120 from the sacrificial protection layer 120 side to the core material 110 side, reaching the core material 110, with the sacrificial protection layer 120 formed on one surface 111 of the core material 110.

[0048] In this embodiment, the protrusions 101, the stepped portions 102, and the recessed portions 104 correspond to the step portions and the divided portions.

[0049] Second Embodiment In this embodiment, differences from the first embodiment will be mainly described. As shown in Fig. 15 , the first bonding material 100 has a bent portion 103 formed by hemming a portion of the first bonding material 100 so that a portion of the sacrificial corrosion protection layer 120 faces another portion. Hemming is also called hemming bending or hemming.

[0050] In this embodiment, the bonded body 1 is composed of a plurality of hemmed first bonding materials 100. That is, it can be said that the first bonding materials 100 are used as the second bonding materials 200. The bent portion 103 of one of the first bonding materials 100 and the bent portion 103 of the other first bonding material 100 are oriented in the same direction.

[0051] Furthermore, a part of the other surface 112 of the core material 110 of one of the first bonding materials 100 and a part of the other surface 112 of the core material 110 of the other first bonding material 100 are fixed together with the adhesive 300. That is, the part of the other surface 112 of the core material 110 of the first bonding material 100 becomes the adhesive portion 124 to which the adhesive 300 is fixed.

[0052] For example, when the bonded body 1 is used in a heat exchanger, the plurality of first bonding materials 100 are arranged so that the bent portions 103 of the first bonding materials 100, i.e., the insides of the tubes of the core material 110, face each other. This allows, for example, cooling water to flow vertically through the space defined by the bent portions 103.

[0053] According to the above configuration, in each core material 110 of each first bonding material 100, the thickness portion 116 between one surface 111 of the core material 110 on which the priority sacrificial portion 121 is formed and the other surface 112 of the core material 110 opposite to the one surface 111 serves as the dividing portion. That is, the thickness portion 116 of the core material 110 divides the priority sacrificial portion 121 of the sacrificial protection layer 120 that will corrode and the adhesive portion 124 of the first bonding material 100 to which the adhesive 300 is fixed. In this embodiment, the entire sacrificial protection layer 120 serves as the priority sacrificial portion 121.

[0054] Therefore, even if corrosion products are generated in the priority sacrificial portion 121, the corrosion products cannot progress to the adhesive portion 124 due to the thickness portion 116. Therefore, the same effects as those of the first embodiment can be obtained.

[0055] As another example, the first bonding material 100 may be hemmed at multiple locations to have multiple folded portions 103. Furthermore, the other surface 112 of the first bonding material 100 corresponding to the folded portions 103 may be fixed to the second bonding material 200 as an adhesive portion 124.

[0056] In the present embodiment, an example is shown in which the first bonding material 100 is used as the second bonding material 200, but this is one example of the second bonding material 200. As the second bonding material 200, various parts such as a block, a plate member, a pipe, etc. can be used.

[0057] In this embodiment, the thickness portion 116 of the core material 110 corresponds to the dividing portion.

[0058] The present disclosure is not limited to the above-described embodiments, and various modifications can be made as follows within the scope of the present disclosure.

[0059] For example, the surface 111 of the core material 110 of the first bonding material 100 is not limited to a flat surface, but may be a curved surface. The surface 111 of the core material 110 may be formed to have a surface required for the bonded body 1.

[0060] The joined body 1 is not limited to being used in a heat exchanger. The joined body 1 may be any structure used in an environment exposed to corrosion. For example, the joined body 1 may be configured as a structure such as a pressure vessel or a sealed vessel. Alternatively, the joined body 1 may be applied to a joint between a vessel and a pipe or a joint between pipes. In other words, the joined body 1 can be applied to a structure that requires airtightness in which the inside and outside must not be connected in a corrosive environment.

[0061] The joined body 1 may be exposed to a corrosive environment other than water, such as air or a refrigerant, etc. Even in such a situation, the corrosion life of the joined body 1 can be improved.

[0062] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A joint comprising: a first joining material (100) including a core material (110) having one surface (111); a sacrificial corrosion protection layer (120) covering the one surface of the core material and having a lower potential than the core material; a second joining material (200) joined to the first joining material; and an adhesive (300) joining the first joining material and the second joining material, wherein the first joining material has a separating portion (101, 102, 116) separating a preferential sacrificial portion (121) of the sacrificial corrosion protection layer that will corrode and an adhesive portion (123, 124) of the first joining material to which the adhesive is fixed.

2. The joined body according to claim 1, wherein the core material is plate-shaped having the one surface, the dividing portion is a stepped portion (101, 102) formed in the core material continuously from one end (113) of the core material to the other end (114) of the core material along one direction parallel to the one surface of the core material, the stepped portion dividing the priority sacrificial portion of the sacrificial protection layer from a non-sacrificial portion (122) of the sacrificial protection layer corresponding to the adhesive portion (123), the difference in position between a first surface (121A) of the priority sacrificial portion and a second surface (122A) of the non-sacrificial portion corresponding to the stepped portion in a vertical direction perpendicular to the one surface of the core material is larger than the thickness of the priority sacrificial portion in the vertical direction, and the adhesive bonds the non-sacrificial portion of the sacrificial protection layer to the second joining material.

3. A joint as described in claim 2, wherein the step portion is a protrusion (101) formed by half-punching from the core material side to the sacrificial protection layer side, or from the sacrificial protection layer side to the core material side, with the sacrificial protection layer formed on one surface of the core material.

4. A joint as described in claim 2, wherein the step portion is a step portion (102) formed by half-punching from the core material side to the sacrificial protection layer side in a step shape of at least one step, with the sacrificial protection layer formed on one surface of the core material, or by half-punching from the sacrificial protection layer side to the core material side in a step shape of at least one step.

5. The joint body described in claim 2, wherein the step portion is a recess (104) formed so as to penetrate the sacrificial protection layer from the sacrificial protection layer side to the core material side and reach the core material when the sacrificial protection layer is formed on one surface of the core material.

6. The joined body according to claim 1, wherein the core material is plate-shaped having the one surface and another surface (112) opposite the one surface, the first joining material is bent so that one portion of the sacrificial corrosion protection layer faces another portion by hemming a portion of the first joining material, the dividing portion is a thickness portion (116) of the core material between the one surface and the other surface, and the adhesive bonds an adhesive portion (124) of the other surface of the core material to the second joining material.

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