Welded structure

Abstract

To stably obtain sufficient joining strength in a welded structure formed by welding a member containing aluminum as a main component and a member containing nickel as a main component.SOLUTION: A welded structure (1) has an interface (L) in which a first member (10) containing aluminium as a main component and a second member (20) containing nickel as a main component and a welded portion (30) formed by melting a part of the interface (L). A nickel-rich layer (40) in which a ratio of a nickel component is more than the aluminum component and an aluminum-rich layer (50) in which a ratio of the aluminum component is more than the nickel component are formed in each of a plurality of projected portions (61-64). In each of welded cross sections of each of the plurality of projected portions (61-64) projecting to the side of the first member (10) more than the interface (L), an area (50) occupied by an aluminum rich layer is fewer than an area (40) occupied by the nickel-rich layer.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a welded structure formed by welding a member mainly composed of aluminum (a member formed of aluminum or an aluminum alloy) and a member mainly composed of nickel (a member formed of nickel or a nickel alloy).

Background Art

[0002] For example, Japanese Patent Application Laid-Open No. 11-73940 (Patent Document 1) discloses a technique for laser-welding a member mainly composed of aluminum and a member mainly composed of nickel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a member mainly composed of aluminum and a member mainly composed of nickel are welded, sufficient joint strength may not be obtained.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to stably obtain sufficient joint strength in a welded structure formed by welding a member mainly composed of aluminum and a member mainly composed of nickel.

Means for Solving the Problems

[0006] (Item 1) The welded structure according to the present disclosure is a welded structure formed by welding a first member mainly composed of aluminum and a second member mainly composed of nickel, and includes an interface where the first member and the second member are in contact with each other, and a weld portion formed by melting a part of the interface. The weld portion includes a plurality of protruding portions each protruding toward the first member side from the interface. In each of the plurality of protruding portions, a nickel-rich layer having a higher ratio of nickel component than aluminum component and an aluminum-rich layer having a higher ratio of aluminum component than nickel component are formed. In the welded cross section of each of the plurality of protruding portions, the area occupied by the aluminum-rich layer is smaller than the area occupied by the nickel-rich layer.

[0007] (Item 2) In the welded structure according to Item 1, the plurality of protruding portions are separated from each other.

[0008] (Item 3) In the welded structure according to Item 1, the bases of the plurality of protruding portions overlap each other.

[0009] (Item 4) In the welded structure according to Item 1, the weld portion has a plurality of bead portions each extending in a first direction and adjacent to each other in a direction intersecting the first direction. The plurality of protruding portions are formed at positions corresponding to the plurality of bead portions, respectively.

Advantages of the Invention

[0010] According to the present disclosure, in a welded structure formed by welding a member mainly composed of aluminum and a member mainly composed of nickel, sufficient bonding strength can be stably obtained.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0013] FIG. 1 is a diagram schematically showing an example of a welded structure 1 according to the present embodiment. The welded structure 1 is formed by welding a plate-shaped first member 10 mainly composed of aluminum and a plate-shaped second member 20 mainly composed of nickel and containing an aluminum component. The welded structure 1 is welded by irradiating laser light toward the outer surface of the second member 20 with the first member 10 and the second member 20 overlapped. In the figure, the Z direction indicates the overlapping direction of the first member 10 and the second member 20, the X direction indicates the longitudinal direction of the second member 20, and the Y direction indicates the direction orthogonal to the X direction and the Z direction.

[0014] Generally, since the welding strength when welding aluminum and nickel is low, it is desirable to ensure the welding strength by increasing the welding area. In the example shown in FIG. 1, a plurality of welding beads 31 to 34 each extending linearly along the X direction are formed in proximity in the Y direction. Each of the welding beads 31 to 34 is formed by moving the laser light in the welding progress direction (X direction). Thus, by forming a plurality of welding beads 31 to 34, the welding area between the first member 10 and the second member 20 becomes large, and the joining strength between the two is ensured.

[0015] FIG. 2 is a diagram showing a welded cross-section of the welded structure 1 according to the present embodiment. The welded structure 1 includes a welded portion 30. The welded portion 30 is formed by melting the periphery of the interface L where the first member 10 and the second member 20 are in contact by irradiating a laser beam.

[0016] The welded portion 30 includes a plurality of protruding portions 61 to 64 that protrude toward the first member 10 side from the interface L. The plurality of protruding portions 61 to 64 are formed at positions corresponding to the plurality of welding beads 31 to 34, respectively. The plurality of protruding portions 61 to 64 are each formed by melting the first member 10 and the second member 20 up to the first member 10 side from the interface L when the welding beads 31 to 34 are formed. In FIG. 2, an example is shown in which one welded portion 30 is formed by the bases of the protruding portions 61 to 64 overlapping each other.

[0017] The welded portion 30 includes a nickel-rich layer 40 and an aluminum-rich layer 50. The nickel-rich layer 40 and the aluminum-rich layer 50 are formed by mixing the nickel component of the second member 20 and the aluminum component of the first member 10 by melting during welding. The nickel-rich layer 40 is a layer in which the proportion of the nickel component is larger than that of the aluminum component. The aluminum-rich layer 50 is a layer in which the proportion of the aluminum component is larger than that of the nickel component. The nickel-rich layer 40 and the aluminum-rich layer 50 are formed in each of the protruding portions 61 to 64.

[0018] The nickel-rich layer 40 is formed from the outer surface 20a of the second member 20 to a region on the first member 10 side from the interface L. The aluminum-rich layer 50 is formed adjacent to the nickel-rich layer 40 so as to cover the surface of the nickel-rich layer 40 on the first member 10 side.

[0019] Among the second member 20, the nickel-rich layer 40, the aluminum-rich layer 50, and the first member 10, the one with the highest strength is the second member 20, the one with the second highest strength after the second member 20 is the nickel-rich layer 40, the one with the third highest strength after the nickel-rich layer 40 is the first member 10, and the one with the lowest strength is the aluminum-rich layer 50.

[0020] In the welded structure 1 according to the present embodiment, as shown in FIG. 2, the area of each aluminum-rich layer 50 of the protruding portions 61 to 64 is smaller than the area of each nickel-rich layer 40 of the protruding portions 61 to 64 (the area on the first member 10 side from the interface L of the nickel-rich layer 40). Further, in the welded structure 1, as shown in FIG. 2, the thickness (Z-direction dimension) of each aluminum-rich layer 50 of the protruding portions 61 to 64 is thinner than the thickness (Z-direction distance from the interface L of the nickel-rich layer 40 to each tip) of each nickel-rich layer 40 of the protruding portions 61 to 64. The thickness of the aluminum-rich layer 50 is, for example, 100 μm or less.

[0021] Welding conditions (such as the intensity of the laser beam for welding, the welding speed, the environmental temperature, etc.) in which the relationship between the nickel-rich layer 40 and the aluminum-rich layer 50 is as shown in FIG. 2 are obtained in advance by experiments or the like, and by welding the first member 10 and the second member 20 under the welding conditions, the welded structure 1 according to the present embodiment can be obtained.

[0022] The aluminum-rich layer 50 has a characteristic that blowholes (voids) are likely to occur compared to the nickel-rich layer 40. When a plurality of blowholes are continuous in the aluminum-rich layer 50, it leads to a decrease in the bonding strength. In the welded structure 1 according to the present embodiment, as described above, since the aluminum-rich layer 50 is thin, it is difficult for blowholes to be continuous in the Z direction in the aluminum-rich layer 50. Therefore, in the welded structure 1 according to the present embodiment, a decrease in the bonding strength can be suppressed.

[0023] FIG. 3 is a view showing a welded cross section of a welded structure according to a comparative example. In the comparative example shown in FIG. 3, the area of each aluminum-rich layer 50 of the protruding portions 61 to 64 is larger than the area of the nickel-rich layer 40 of each of the protruding portions 61 to 64 (the area on the first member 10 side from the interface L of the nickel-rich layer 40). Further, in the comparative example shown in FIG. 3, the thickness of each aluminum-rich layer 50 of the protruding portions 61 to 64 is thicker than the thickness of the nickel-rich layer 40 of the protruding portions 61 to 64 (the Z-direction distance from the interface L of the nickel-rich layer 40 to each tip). Thus, in the comparative example shown in FIG. 3, since the aluminum-rich layer 50 is thick, blowholes are likely to be continuous in the Z direction in the aluminum-rich layer 50, and there is a concern that the bonding strength may decrease. On the other hand, in the welded structure 1 according to the present embodiment, as described above, since the aluminum-rich layer 50 is thin and blowholes are difficult to be continuous in the Z direction, sufficient bonding strength can be stably obtained.

[0024] As described above, the welded structure 1 according to the present embodiment includes an interface L where the first member 10 mainly composed of aluminum and the second member 20 mainly composed of nickel are in contact with each other, and a welded portion 30 formed by melting the periphery of the interface L. The welded portion 30 includes a plurality of protruding portions 61 to 64 that are each arranged along the interface L and protrude toward the first member 10 side from the interface L. In each of the plurality of protruding portions 61 to 64, a nickel-rich layer 40 having a higher ratio of nickel component than aluminum component and an aluminum-rich layer 50 having a higher ratio of aluminum component than nickel component are formed. In the welded cross section of each of the plurality of protruding portions 61 to 64, the area occupied by the aluminum-rich layer 50 is smaller than the area occupied by the nickel-rich layer 40.

[0025] According to the welded structure 1 according to the present embodiment, the thickness of the aluminum-rich layer 50 where blowholes are likely to occur is thin, and thus blowholes are difficult to be three-dimensionally continuous in the aluminum-rich layer 50. As a result, in the welded structure 1 formed by welding the first member 10 mainly composed of aluminum and the second member 20 mainly composed of nickel, sufficient bonding strength can be stably obtained.

[0026] Further, in the welded structure 1 according to the present embodiment, the bases of the plurality of protruding portions 61 to 64 overlap each other. In such a structure, the distance between the plurality of weld beads 31 to 34 is short, and during the process of sequentially forming the plurality of weld beads 31 to 34, heat is easily transferred to the already formed weld beads, and there is also a concern that the aluminum-rich layer 50 becomes thick and the joining strength decreases due to this influence. However, in the welded structure 1 according to the present embodiment, even in the structure where the bases of the plurality of protruding portions 61 to 64 overlap each other, welding conditions are obtained in advance by experiments or the like so that the area (thickness) of the aluminum-rich layer 50 is suppressed to be thin as described above, and by welding the first member 10 and the second member 20 under the welding conditions, a decrease in joining strength can be stably suppressed.

[0027] [Modification Example 1] In the welded structure 1 according to the above-described embodiment, the bases of the plurality of protruding portions 61 to 64 overlap each other, but the plurality of protruding portions 61 to 64 may be separated from each other.

[0028] FIG. 4 is a view of an example of the welded structure 1A according to the present modification example 1 as viewed from the Z direction. In the welded structure 1A according to the present modification example 1, as shown in FIG. 4, a plurality of weld beads 31a to 34a are formed at a predetermined distance in the Y direction.

[0029] FIG. 5 is a view showing a welded cross section of the welded structure 1A according to the present modification example 1. In the welded structure 1A according to the present modification example 1, a plurality of protruding portions 61a to 64a protruding to the side of the first member 10 from the interface L are separated from each other.

[0030] In the welded structure 1A according to the present modification example 1, the plurality of protruding portions 61a to 64a are separated from each other, and during the process of sequentially forming the plurality of weld beads 31a to 34a, the amount of heat transferred to the already formed weld beads can be reduced. As a result, the thickening of the aluminum-rich layer 50 is suppressed, and blow holes are less likely to be continuous. As a result, it is easier to further suppress a decrease in the strength of the welded portion.

[0031] [Modification Example 2] In the above-described embodiment and Modification Example 1, an example in which linear welding beads 31 to 34 each extending in the X direction are formed side by side in the Y direction has been described. However, the shape of the welding bead is not necessarily limited to being linear.

[0032] FIG. 6 is a view of an example of the welded structure 1B according to this Modification Example 2 as viewed from the Z direction. In the welded structure 1B according to this Modification Example 1, as shown in FIG. 6, one welding bead 31b is formed in a curved shape. Although there are portions where the welding bead 31b intersects in part, most of the other portions are separated from each other by a predetermined distance without overlapping. By preventing the welding bead 31b from overlapping in this way, the amount of heat transferred to the already formed portion can be reduced in the process of forming a new portion of the welding bead 31b. As a result, similar to Modification Example 1, the thickening of the aluminum-rich layer 50 is suppressed, and blowholes are less likely to be continuous, so that a decrease in the strength of the welded portion can be more easily suppressed.

[0033] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0034] 1, 1A, 1B Welded structures, 10 First member, 20 Second member, 20a Outer surface, 30 Welded portion, 31 to 34, 31a to 34a, 31b Welding beads, 40 Nickel-rich layer, 50 Aluminum-rich layer, 61 to 64, 61a to 64a Protruding portions, L Interface.

Claims

Claim 1 A welded structure formed by welding a first member mainly composed of aluminum and a second member mainly composed of nickel, an interface where the first member and the second member are in contact, and a welded portion formed by melting a part of the interface, wherein the welded portion includes a plurality of protruding portions each protruding toward the first member side from the interface, and each of the plurality of protruding portions is formed with a nickel-rich layer having a higher ratio of nickel component than aluminum component and an aluminum-rich layer having a higher ratio of aluminum component than nickel component, a welded structure in which, in the welded cross section of each of the plurality of protruding portions, the area occupied by the aluminum-rich layer is smaller than the area occupied by the nickel-rich layer. Claim 2 The welded structure according to claim 1, wherein the plurality of protruding portions are spaced apart from each other. Claim 3 The welded structure according to claim 1, wherein the bases of the plurality of protruding portions overlap each other. Claim 4 the welded portion has a plurality of bead portions each extending in a first direction and adjacent to each other in a direction intersecting the first direction, The welded structure according to claim 1, wherein the plurality of protruding portions are formed at positions corresponding to the plurality of bead portions, respectively.

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