Junction structure and method of junction

Abstract

To suppress generation of electric corrosion in each overlapping part of a first member, a second member, and a third member.SOLUTION: A third member 30 includes a lamination part 31, a first flange part 32, and a second flange part 33. The lamination part 31 solidifies in a first penetration part 11 and a second penetration part 21 and extends in a lamination direction. The first flange part 32 is provided integrally with the lamination part 31 and presses a peripheral edge part of the first penetration part 11 in a plated layer 15 while overhanging outward from the first penetration part 11. The second flange part 33 is provided integrally with the lamination part 31 and presses a peripheral edge part of the second penetration part 21 in a second member 20 while overhanging outward from the second penetration part 21.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a joining structure and a joining method. [Background technology]

[0002] Patent Document 1 discloses a joining structure in which a first member (first metal material) and a second member (dissimilar material) that is difficult to weld to the first member are overlapped, and a third member (third material) is melted and arc-welded through a penetration portion of the second member.

[0003] At this time, the molten third member forms a flange portion that covers the outer periphery of the upper surface of the penetration portion of the second member, thereby fixing the first member and the second member together by the compressive fixing force between the flange portion and the first member due to solidification and shrinkage of the third member relative to the first member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 030272 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the invention of Patent Document 1, there is a risk that moisture may enter from the outside through the gap between the overlapping surfaces of the flange portion of the third member and the second member and the gap between the overlapping surfaces of the first member and the second member. The moisture may then cause electrolytic corrosion in the overlapping portion of the flange portion of the third member and the second member and the overlapping portion of the first member and the second member, resulting in a decrease in joint strength.

[0006] The present invention has been made in view of the above points, and an object thereof is to suppress the occurrence of electrolytic corrosion in the overlapping portions of the first member, the second member, and the third member. [Means for solving the problem]

[0007] The first invention is a joining structure in which a first member made of a metal material, a second member made of a material that is difficult to weld to the first member and laminated on the first member, and a third member made of a filler metal of the same type as the second member are joined together, wherein a plating layer made of the same type of material as the second member is provided on a surface of the first member, the first member is provided with a first through portion that penetrates in the lamination direction, and the second member is provided with a second through portion that penetrates in the lamination direction, and the third member has: a lamination portion that solidifies inside the first through portion and the second through portion and extends in the lamination direction, a first flange portion that is formed integrally with the lamination portion, protruding outward beyond the first through portion and pressing against a peripheral edge of the first through portion in the plating layer, and a second flange portion that is formed integrally with the lamination portion, protruding outward beyond the second through portion and pressing against a peripheral edge of the second through portion in the second member.

[0008] In the first invention, by providing a plating layer made of the same material as the second member on the surface of the first member, the overlapping portion between the first member and the second member is made of the same material. Also, the overlapping portion between the first flange portion of the third member and the first member and the overlapping portion between the second flange portion of the third member and the second member are also made of the same material.

[0009] In this way, by eliminating the areas where the metal material and the dissimilar material directly overlap in the overlapping portions of the first member, the second member, and the third member, it is possible to suppress the occurrence of electrolytic corrosion and ensure the joining strength.

[0010] Furthermore, by compressing and fixing the first member and the second member with the first flange portion and the second flange portion, the overlapping portions of the first member and the second member are tightly attached, making it difficult for moisture to penetrate from the outside.

[0011] A second aspect of the present invention is the joining structure of the first aspect, wherein an opening area of the second through portion is larger than an opening area of the first through portion.

[0012] In the second invention, the third member as a filler metal can be easily inserted through the second penetration portion, and the joining area between the second member and the third member can be increased, ensuring the joining strength.

[0013] A third invention is the joining structure of the first or second invention, wherein the second penetrating portion has a tapered portion that tapers toward the first member.

[0014] In the third invention, by providing a tapered portion in the second penetrating portion, the molten third member can easily flow toward the center of the second penetrating portion. Also, by solidifying the third member into a shape that follows the tapered portion of the second penetrating portion, the bonding area between the second member and the third member can be increased, and bonding strength can be ensured.

[0015] A fourth aspect of the present invention is the joining structure of the third aspect, wherein the first penetrating portion has a tapered portion that tapers toward the side opposite to the second member.

[0016] In the fourth aspect of the present invention, the first through portion is provided with a tapered portion, which makes it easier for the molten third member to flow toward the center of the first through portion.

[0017] A fifth invention is the joining structure of the first or second invention, wherein the amount of protrusion of the first flange portion from the peripheral edge portion of the first penetrating portion is 0.5 to 2.0 mm.

[0018] In the fifth aspect of the present invention, the amount of projection of the first flange portion from the peripheral edge portion of the first penetrating portion is appropriately set, thereby ensuring the joining strength.

[0019] A sixth invention is a joining method for joining a first member made of a metallic material and a second member made of a material that is difficult to weld to the first member and laminated on the first member, the method comprising: a first step of disposing a first mold having a first recess with a larger opening area than the first recess such that an opening side of the first recess abuts against the first member; a second step of filling molten metal obtained by melting a filler metal of the same type as the second member into the first recess through the first and second penetration portions; and a second step of disposing a first mold having a first recess with a larger opening area than the first penetration portion so that an opening side of the first recess abuts against the first member. a third step of filling the molten metal into the through portion and the second penetrating portion; a fourth step of filling the molten metal so that it protrudes outward beyond the peripheral edge of the second penetrating portion; and a fifth step of solidifying the molten metal to form a third member having a laminated portion, a first flange portion formed integrally with the laminated portion, and a second flange portion formed integrally with the laminated portion, wherein the laminated portion solidifies inside the first penetrating portion and the second penetrating portion and extends in the lamination direction, the first flange portion protrudes outward beyond the first penetrating portion and presses against the peripheral edge of the first penetrating portion in the plating layer, and the second flange portion protrudes outward beyond the second penetrating portion and presses against the peripheral edge of the second penetrating portion in the second member.

[0020] In the sixth aspect of the present invention, the first flange portion of the third member can be molded with high precision by filling the first recess of the first mold with molten metal. Also, a wide first flange portion can be formed.

[0021] A seventh aspect of the present invention is the joining method of the sixth aspect, wherein the first mold is made of a material having a higher melting point than the third member.

[0022] In the seventh aspect of the present invention, the first mold is prevented from being deformed by the molten third member.

[0023] An eighth invention is a joining method according to the sixth or seventh invention, which includes, before the second step, a step of positioning a second mold having a second recess with a larger opening area than the second through-hole and a communicating portion communicating with the second recess so that the opening side of the second recess abuts the second member, and in the second step, the molten metal is filled into the first recess through the communicating portion, the first through-hole, and the second through-hole, and in the fourth step, the molten metal is filled inside the second recess.

[0024] In the eighth aspect of the present invention, the second flange portion of the third member can be molded with high precision by filling the second recess of the second mold with molten metal. Also, a wide second flange portion can be formed.

[0025] A ninth aspect of the present invention is the joining method according to the eighth aspect, wherein the second mold is made of a material having a higher melting point than the third member.

[0026] In the ninth aspect of the present invention, the second mold is prevented from being deformed by the molten third member. [Effects of the Invention]

[0027] According to the present invention, it is possible to prevent electrolytic corrosion from occurring in the overlapping portions of the first member, the second member, and the third member. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a perspective view for explaining a joint structure according to the first embodiment. [Figure 2] FIG. 2 is a side cross-sectional view for explaining a joining structure. [Figure 3] FIG. 2 is a diagram illustrating the configuration of a first mold. [Figure 4] FIG. 10 is a side cross-sectional view for explaining a joint structure according to a second embodiment. [Figure 5] FIG. 11 is a side cross-sectional view for explaining a joint structure according to a third embodiment. [Figure 6]FIG. 10 is a side cross-sectional view for explaining a joint structure according to a fourth embodiment. [Figure 7] FIG. 11 is a side cross-sectional view for explaining a joint structure according to a fifth embodiment. [Figure 8] FIG. 10 is a perspective view illustrating a joint structure according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0030] First Embodiment 1 and 2 show a joining structure for joining together a first member 10 made of a metal material, a second member 20 made of a material that is difficult to weld to the first member 10 and laminated on the first member 10, and a third member 30 made of a filler material.

[0031] The first member 10 is a plate-shaped member made of a metal material. A plating layer 15 is provided on the surface of the first member 10. The plating layer 15 is made of the same type of material as the second member 20. The plating layer 15 is provided on the upper and lower surfaces of the first member 10. The plating layer 15 may also be provided on the outer periphery of the first member 10 so as to cover the entire first member 10. The first member 10 is provided with a first through portion 11 that penetrates in the stacking direction. The first through portion 11 is a circular through hole.

[0032] The second member 20 is a plate-like member made of a material that is difficult to weld to the first member 10. The second member 20 is overlaid on the upper side of the first member 10. The second member 20 is provided with a second through portion 21 that penetrates in the stacking direction. The second through portion 21 is a circular through hole. Note that the second member 20 may also be configured to be overlaid on the lower side of the first member 10.

[0033] The third member 30 is made of a filler metal that is the same type of metal as the plating layer 15 of the first member 10 and the second member 20. Here, the term "similar metals" refers to metals that can be welded to each other, and not only to metals of the same material, but also to metals that have good weldability, such as ferrous metals and non-ferrous metals. In other words, "similar metals" refers to materials of the same type that are compatible for welding.

[0034] Specifically, the following combinations of the second member 20 and the third member 30 during welding can be cited. For example, combinations of ferrous metal materials include mild steel and mild steel, stainless steel and stainless steel, and mild steel and high-tensile steel (high-tensile steel). Furthermore, combinations of non-ferrous metal materials include aluminum and aluminum, aluminum and aluminum alloy, aluminum alloy and aluminum alloy, copper and copper, copper and copper alloy, copper alloy and copper alloy, etc.

[0035] Furthermore, the second member 20 as a different material is made of a material different from that of the first member 10, and is difficult to weld to the first member 10.

[0036] For example, when the first member 10 as a metal material is an iron-based metal material, the second member 20 as a different material is a non-ferrous metal material such as copper or aluminum.

[0037] The third member 30 has a laminated portion 31, a first flange portion 32, and a second flange portion 33. The laminated portion 31 is formed by solidifying molten filler material inside the first through portion 11 and the second through portion 21. The laminated portion 31 extends inside the first through portion 11 and the second through portion 21 in the lamination direction.

[0038] The first flange portion 32 is provided integrally with the lower end portion in the stacking direction of the laminated portion 31. The first flange portion 32 protrudes outward beyond the first penetrating portion 11. The first flange portion 32 is welded to the peripheral edge of the first penetrating portion 11 in the plating layer 15 of the first member 10. The first flange portion 32 presses against the peripheral edge of the first penetrating portion 11 in the first member 10.

[0039] The second flange portion 33 is provided integrally with the upper end portion in the stacking direction of the laminated portion 31. The second flange portion 33 protrudes outward beyond the second through portion 21. The second flange portion 33 is welded to the peripheral edge portion of the second through portion 21 of the second member 20. The second flange portion 33 presses against the peripheral edge portion of the second through portion 21 of the second member 20.

[0040] Then, as the third member 30 solidifies and shrinks, the first member 10 and the second member 20 are compressed and fixed between the first flange portion 32 and the second flange portion 33.

[0041] <Joining method> Next, a description will be given of a joining method for joining the first member 10, the second member 20, and the third member 30. In the following description, a case will be described in which mild steel material is used as the first member 10, aluminum plating is used as the plating layer 15 of the first member 10, aluminum material is used as the second member 20, and aluminum material is used as the third member 30, which is a filler metal.

[0042] Although the case where aluminum plating is used as the plating layer 15 of the first member 10, aluminum material is used as the second member 20, and aluminum material is used as the third member 30 which is a filler metal, copper may be used instead of aluminum. Specifically, this is the case where copper plating is used as the plating layer 15 of the first member 10, copper material is used as the second member 20, and copper material is used as the third member 30 which is a filler metal.

[0043] 2, the arc welding machine 1 includes a nozzle 2 and a tip 3. The nozzle 2 supplies a shielding gas and the like to a welding point of an object to be welded. The tip 3 supplies a welding current to a third member 30 serving as a filler metal.

[0044] First, the second member 20 is stacked on the top surface of the first member 10. At this time, the first through portion 11 of the first member 10 and the second through portion 21 of the second member 20 are arranged substantially concentrically when viewed from the stacking direction.

[0045] A first mold 40 is placed on the underside of the first member 10. The first mold 40 is made of a material with a higher melting point than the molten third member 30. For example, if the third member 30 is made of aluminum, the first mold 40 is preferably made of carbon steel, cast iron, or cast steel.

[0046] The first mold 40 has a first recess 41. The first recess 41 has a larger opening area than the first through-hole 11. The first mold 40 is disposed so that the opening side of the first recess 41 abuts against the first member 10.

[0047] The arc welding machine 1 generates an arc 5 by supplying a welding current while feeding a third member 30, which is a filler material of the same type as the second member 20.

[0048] The third member 30 melted by arc welding is filled into the first recess 41 through the first through portion 11 and the second through portion 21. In the first recess 41, the molten third member 30 flows outward from the first through portion 11 and spreads in a flange shape.

[0049] The molten third member 30 fills up the first recess 41, and then fills up and stacks inside the first through portion 11 and the second through portion 21. Then, after filling up the first through portion 11 and the second through portion 21, the molten third member 30 flows outward from the peripheral edge of the second through portion 21 and spreads out in a flange shape.

[0050] Then, as the molten metal solidifies and shrinks, a third member 30 is formed, which has a laminated portion 31, a first flange portion 32 provided integrally with the laminated portion 31, and a second flange portion 33 provided integrally with the laminated portion 31. Thereafter, the first mold 40 is removed.

[0051] The first flange portion 32 projects outward from the first through portion 11 and is welded to the peripheral edge of the first through portion 11 in the plating layer 15. The second flange portion 33 projects outward from the second through portion 21 and is welded to the peripheral edge of the second through portion 21 in the second member 20.

[0052] Here, in the second member 20, heat is sufficiently trapped, which makes it easy for the second flange portion 33 to expand. Therefore, the outer diameter of the second flange portion 33 may be formed to be larger than the outer diameter of the first flange portion 32.

[0053] In this way, by melting the welding wire as the filler material, which is the third member 30, and supplying it to the first member 10 through the first through-hole 11 and the second through-hole 21, flange-shaped beads are formed on the surfaces of the first member 10 and the second member 20 to ensure strength, and the first member 10 and the second member 20 are clamped together by compression fixation.

[0054] <Configuration of the first mold> A specific configuration of the first die 40 will be described below with reference to Fig. 3. Here, the wire diameter of the third member 30 as a filler metal is set to φ1.2 mm.

[0055] In this case, the inner diameter of the first through portion 11 of the first member 10 is preferably φ7 mm or more. Also, the inner diameter of the second through portion 21 of the second member 20 is preferably φ7 mm or more. In the example shown in Fig. 3, the inner diameter of the first through portion 11 of the first member 10 is φ8.0 mm. The inner diameter of the second through portion 21 of the second member 20 is φ8.0 mm.

[0056] Furthermore, the amount of protrusion of the first flange portion 32 from the first through portion 11, i.e., the dimensional difference between the inner diameter of the opening side of the first recess 41 in the first mold 40 and the inner diameter of the first through portion 11, is preferably 0.5 to 2.0 mm. In the example shown in FIG. 3, the inner diameter of the opening side of the first recess 41 is φ10.0 mm. As a result, the first flange portion 32 protrudes radially outward by 1.0 mm along the periphery of the first through portion 11. Furthermore, the maximum depth of the first recess 41 in the first mold 40 is 4.0 mm.

[0057] In this way, by appropriately setting the inner diameters of the first through portion 11 and the second through portion 21 and the inner diameter of the opening side of the first recess 41 in the first mold 40, it is possible to sufficiently fill the molten third member 30 into the first recess 41. This makes it possible to form the first flange portion 32 with an appropriate shape.

[0058] -Effects of this embodiment- As described above, according to the joining structure of this embodiment, by providing the plating layer 15 made of the same type of material as the second member 20 on the surface of the first member 10, the overlapping portion between the first member 10 and the second member 20 is made of the same type of material. In addition, the overlapping portion between the first flange portion 32 of the third member 30 and the first member 10 and the overlapping portion between the second flange portion 33 of the third member 30 and the second member 20 are also made of the same type of material.

[0059] In this way, by eliminating the overlapping areas of the metal material and the dissimilar material in the overlapping portions of the first member 10, the second member 20, and the third member 30, it is possible to suppress the occurrence of electrolytic corrosion and ensure the joining strength.

[0060] Furthermore, by compressing and fixing the first member 10 and the second member 20 together using the first flange portion 32 and the second flange portion 33, the overlapping portions of the first member 10 and the second member 20 are tightly attached, making it difficult for moisture to penetrate from the outside.

[0061] The laminated portion 31 disposed inside the first penetrating portion 11 is in contact with the first member 10, and if moisture penetrates, there is a risk of an intermetallic compound being generated. However, this portion is separated from the first flange portion 32, and does not have much of an effect on ensuring the joining strength. Therefore, it is not necessary to provide a plated layer 15 on the inner peripheral surface of the first penetrating portion 11, but a configuration in which a plated layer 15 is provided may be adopted.

[0062] Furthermore, by filling the first recess 41 of the first mold 40 with molten metal, it is possible to mold the first flange portion 32 of the third member 30 with high precision. Also, it is possible to form the first flange portion 32 with a large width.

[0063] Furthermore, by melt-joining materials of the same type, it is possible to prevent the intrusion of moisture from the outside and to suppress electrolytic corrosion without using different construction methods such as commonly used adhesives, sealants, and sealing agents.

[0064] Second Embodiment Hereinafter, the same parts as those in the first embodiment will be assigned the same reference numerals, and only the differences will be described.

[0065] 4, the second member 20 has a second through portion 21. The opening area of the second through portion 21 is larger than the opening area of the first through portion 11.

[0066] The third member 30 is melted by arc welding. The molten third member 30 fills the first recess 41, and then fills the first through portion 11. After filling the first through portion 11, the molten third member 30 fills the second through portion 21. Inside the second through portion 21, the molten third member 30 flows outward from the first through portion 11 and spreads. After filling the second through portion 21, the molten third member 30 flows outward from the peripheral edge of the second through portion 21 and spreads in a flange shape.

[0067] As described above, according to the joining structure of this embodiment, the third member 30, which is a filler material, can be easily inserted through the second penetrating portion 21. In addition, the joining area between the second member 20 and the third member 30 can be increased, and the joining strength can be ensured.

[0068] Third Embodiment 5, the second member 20 has a second penetrating portion 21. The second penetrating portion 21 has a second tapered portion 22 that tapers toward the first member 10.

[0069] The third member 30 is melted by arc welding. The molten third member 30 flows along the second tapered portion 22 of the second penetration portion 21 so as to gather at the center of the second penetration portion 21.

[0070] As described above, according to the joining structure of this embodiment, the molten third member 30 can easily flow toward the center of the second penetrating portion 21. Furthermore, by solidifying the third member 30 into a shape that follows the second tapered portion 22 of the second penetrating portion 21, the joining area between the second member 20 and the third member 30 can be increased and the joining strength can be ensured.

[0071] Fourth Embodiment 6, the first member 10 has a first penetrating portion 11. The first penetrating portion 11 has a first tapered portion 12 that tapers toward the opposite side from the second member 20.

[0072] The second member 20 has a second penetrating portion 21. The second penetrating portion 21 has a second tapered portion 22 that tapers toward the first member 10.

[0073] 4, the inclination angles of the first tapered portion 12 and the second tapered portion 22 are set so that the first tapered portion 12 and the second tapered portion 22 extend continuously when the first member 10 and the second member 20 are stacked. Note that the inclination angle of the first tapered portion 12 and the inclination angle of the second tapered portion 22 may be different.

[0074] The third member 30 is melted by arc welding. The molten third member 30 flows along the second tapered portion 22 of the second penetrating portion 21 and the first tapered portion 12 of the first member 10, and gathers at the center of the second penetrating portion 21 and the first penetrating portion 11.

[0075] As described above, according to the joining structure according to this embodiment, the molten third member 30 can easily flow toward the center of the second through portion 21 and the first through portion 11.

[0076] Fifth Embodiment 7, the second member 20 is stacked on top of the upper surface of the first member 10. At this time, the first through portion 11 of the first member 10 and the second through portion 21 of the second member 20 are arranged substantially concentrically when viewed from the stacking direction.

[0077] A first mold 40 is placed on the underside of the first member 10. The first mold 40 has a first recess 41. The first recess 41 has a larger opening area than the first through-hole 11. The first mold 40 is placed so that the opening side of the first recess 41 abuts against the first member 10.

[0078] A second mold 50 is placed on the upper surface of the second member 20. The second mold 50 is made of a material with a higher melting point than the molten third member 30. For example, when the third member 30 is made of aluminum, the second mold 50 is preferably made of carbon steel, cast iron, or cast steel.

[0079] The second mold 50 has a second recess 51 and a communication portion 52. The second recess 51 has a larger opening area than the second through portion 21. The communication portion 52 is a hole that communicates with the second recess 51. The second mold 50 is positioned so that the opening side of the second recess 51 abuts against the second member 20.

[0080] The third member 30 melted by arc welding is filled into the first recess 41 via the communicating portion 52, the first through portion 11, and the second through portion 21. In the first recess 41, the molten third member 30 flows outward from the first through portion 11 and spreads in a flange shape.

[0081] The molten third member 30 fills up the first recess 41, and then fills the insides of the first through portion 11 and the second through portion 21 and is stacked.

[0082] Then, the molten third member 30 fills up the first through portion 11 and the second through portion 21, and then fills the second recess 51. In the second recess 51, the molten third member 30 flows outward from the second through portion 21 and spreads in a flange shape.

[0083] Then, as the molten metal solidifies and shrinks, a third member 30 is formed, which has a laminated portion 31, a first flange portion 32 provided integrally with the laminated portion 31, and a second flange portion 33 provided integrally with the laminated portion 31. Thereafter, the first mold 40 and the second mold 50 are removed.

[0084] As described above, according to the joining structure of this embodiment, the first flange portion 32 and the second flange portion of the third member can be molded with high precision by filling the first recessed portion 41 of the first mold 40 and the second recessed portion of the second mold 50 with molten metal. Also, the first flange portion 32 and the second flange portion 33 can be formed with large widths.

[0085] Other Embodiments The above embodiment may be configured as follows.

[0086] In this embodiment, the first member 10 and the second member 20 are compressed and fixed between the first flange portion 32 and the second flange portion 33, but three or more members may be sandwiched and compressed and fixed.

[0087] In this embodiment, the second through-hole 21 of the second member 20 is a circular through-hole, and during arc welding, the welding point as the welding location is stopped and the third member 30 is fed toward the second through-hole 21 as a filler metal, but this is not limited to this form.

[0088] For example, as shown in FIG. 8, the second through-hole 21 of the second member 20 may be a rectangular through-hole, and during arc welding, the welding point may be moved from one end of the second through-hole 21 to the other end in the longitudinal direction, while the third member 30 as a filler metal is fed toward the second through-hole 21. [Industrial Applicability]

[0089] As described above, the present invention has the highly practical effect of being able to suppress the occurrence of electrolytic corrosion in the overlapping portions of the first member, the second member, and the third member, and is therefore extremely useful and has high industrial applicability. [Explanation of symbols]

[0090] 10 First member 11 First penetration 12 First tapered section 15 plating layer 20 Second member 21 Second penetration 22 Second tapered section 30 Third member 31 Lamination section 32 First flange 33 Second flange 40 First mold 41 First recess 50 Second mold 51 Second recess 52 Communication part

Claims

1. A joining structure in which a first member made of a metal material, a second member made of a material that is difficult to weld to the first member and laminated on the first member, and a third member made of a filler material of the same type as the second member are joined together, a plating layer made of the same material as the second member is provided on a surface of the first member; The first member is provided with a first penetrating portion that penetrates in the stacking direction, The second member is provided with a second penetrating portion that penetrates in the stacking direction, The third member is a stacked portion solidified inside the first through portion and the second through portion and extending in a stacking direction; a first flange portion that is integral with the laminated portion, that protrudes outward beyond the first penetration portion, and that presses against a peripheral edge portion of the first penetration portion in the plating layer; a second flange portion that is integral with the laminated portion, that projects outward beyond the second penetration portion, and that presses against a peripheral edge portion of the second penetration portion of the second member; Joint structure.

2. The joining structure of claim 1, The opening area of the second through portion is larger than the opening area of the first through portion. Joint structure.

3. The joining structure according to claim 1 or 2, The second penetrating portion has a tapered portion that tapers toward the first member. Joint structure.

4. The joining structure of claim 3, The first penetrating portion has a tapered portion that tapers toward the opposite side to the second member. Joint structure.

5. The joining structure according to claim 1 or 2, The amount of protrusion of the first flange portion from the peripheral edge portion of the first penetrating portion is 0.5 to 2.0 mm. Joint structure.

6. A joining method for joining a first member made of a metal material and a second member made of a material that is difficult to weld to the first member and laminated on the first member, comprising: a plating layer made of the same material as the second member is provided on a surface of the first member; The first member is provided with a first penetrating portion that penetrates in the stacking direction, The second member is provided with a second penetrating portion that penetrates in the stacking direction, a first step of disposing a first mold having a first recess having an opening area larger than that of the first through-hole so that an opening side of the first recess abuts against the first member; a second step of filling the first recess with molten metal obtained by melting a filler material of the same type as the second member through the first penetration portion and the second penetration portion; a third step of filling the first penetration portion and the second penetration portion with the molten metal; a fourth step of filling the molten metal so that it extends outward beyond a peripheral edge of the second penetration portion; a fifth step of solidifying the molten metal to form a third member having a laminated portion, a first flange portion formed integrally with the laminated portion, and a second flange portion formed integrally with the laminated portion; the laminated portion solidifies inside the first through portion and the second through portion and extends in the lamination direction, the first flange portion projects outward from the first penetration portion and presses a peripheral edge portion of the plating layer at the first penetration portion; The second flange portion projects outward from the second penetration portion and presses a peripheral edge portion of the second penetration portion of the second member. Joining method.

7. The joining method according to claim 6, The first mold is made of a material having a higher melting point than the third member. Joining method.

8. The joining method according to claim 6 or 7, a step, prior to the second step, of placing a second mold having a second recess having an opening area larger than that of the second through-hole and a communication portion communicating with the second recess such that an opening side of the second recess abuts against the second member; In the second step, the molten metal is filled into the first recess through the communication portion, the first through portion, and the second through portion; In the fourth step, the molten metal is filled into the second recess. Joining method.

9. The joining method according to claim 8, The second mold is made of a material having a higher melting point than the third member. Joining method.

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