Method for producing joined body

Abstract

To provide a technique for suppressing generation of brittle intermetallic compounds likely to be produced in welding between an iron-based metal member and an aluminum-based metal member.SOLUTION: A method for producing a joined body formed by welding using a weld metal member comprises irradiating the weld metal member with laser light and forming a joint portion by joining an iron-based metal member and an aluminum-based metal member with the molten weld metal member, wherein the joint portion is formed so as to extend across a first joining surface of the iron-based metal member and a second joining surface of the aluminum-based metal member, and short-wavelength laser light having a wavelength of 600 nm or less is used as the laser light.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a bonded body. [Background technology]

[0002] It is known that when an iron-based metal member and an aluminum-based metal member are directly welded together to form a composite material of the iron-based metal member and the aluminum-based metal member, brittle intermetallic compounds are formed at the joint.

[0003] Patent Document 1 discloses a method for controlling the formation of brittle intermetallic compounds by forming a weld metal joint that joins an iron-based metal member and an aluminum-based metal member by MIG welding using a filler metal that is an alloy containing nickel and copper and has a nickel content of 30 to 80 mass %. The weld metal joint contains nickel, copper, iron, and aluminum in specific proportions at the center. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-167013 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even when forming a weld metal part as in the above-mentioned Patent Document 1, in the case of welding using a large amount of heat input, for example, a near-infrared laser, the aluminum-based metal member is likely to be heated simultaneously when the filler metal is melted. Since aluminum has a lower melting point than nickel or copper, if the aluminum-based metal member is heated simultaneously when the filler metal is melted, it is likely to melt. Therefore, depending on the amount of heat input during melting, there is a problem in that the melted aluminum and iron are likely to mix, forming a brittle intermetallic compound.

[0006] An object of one aspect of the present disclosure is to provide a technique for suppressing the formation of brittle intermetallic compounds that tend to occur during welding of an iron-based metal member and an aluminum-based metal member. [Means for solving the problem]

[0007] One aspect of the present disclosure is a method for manufacturing a joined body formed by welding using a deposited metal member, the method comprising: irradiating the deposited metal member with a laser beam to form a joint that joins an iron-based metal member and an aluminum-based metal member with the molten deposited metal member. The joint is formed so as to straddle a first joining surface of the iron-based metal member and a second joining surface of the aluminum-based metal member. A short-wavelength laser beam having a wavelength of 600 nm or less is used as the laser beam.

[0008] While short-wavelength laser light tends to have a high absorption rate for metals commonly used in weld metal members, it has a low absorption rate for aluminum. Therefore, in the above-described configuration, when the weld metal member is melted by irradiation with short-wavelength laser light, the aluminum-based metal member is not likely to be heated at the same time, and as a result, aluminum is not likely to melt out of the aluminum-based metal member. Therefore, it is possible to suppress the formation of brittle intermetallic compounds that tend to occur when welding an iron-based metal member and an aluminum-based metal member.

[0009] In one aspect of the present disclosure, the deposited metal component may be a copper-based metal component. Copper has a high absorptivity for short wavelength laser light, so the above-described configuration allows the copper-based metal member to be melted stably.

[0010] In one aspect of the present disclosure, in addition to short wavelength laser light, near-infrared laser light with a wavelength in the near-infrared region may be used as the laser light. In this configuration, the short-wavelength laser beam melts the weld metal members, and the near-infrared laser beam tends to maintain the molten state of the weld metal members. This makes it easier to spread the molten weld metal members over the joining surfaces of the iron-based metal members and the aluminum-based metal members. This results in a stronger joining of the iron-based metal members and the aluminum-based metal members. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a side view schematically showing a joined body. [Figure 2] 10A to 10C are diagrams for explaining a method for manufacturing a bonded body. [Figure 3] FIG. 1 is a diagram showing the relationship between the wavelength of laser light and the absorptance of a metal material. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. Configuration] The joined body 100 shown in Fig. 1 is a composite material in which two different types of metal members, an iron-based metal member 1 and an aluminum-based metal member 2, are joined together. As will be described in detail later, the joined body 100 is formed by welding using a deposited metal member 3. The joined body 100 includes the iron-based metal member 1, the aluminum-based metal member 2, and a joining portion 3A.

[0013] 1 and 2, in this embodiment, the iron-based metal member 1 and the aluminum-based metal member 2 are, for example, rectangular flat-plate members. The iron-based metal member 1 is made of a metal containing iron as a main component (in other words, iron or an iron alloy). The aluminum-based metal member 2 is made of a metal containing aluminum as a main component (in other words, aluminum or an aluminum alloy). The plate thicknesses of the iron-based metal member 1 and the aluminum-based metal member 2 may be the same or different.

[0014] In the following description, the surfaces of the iron-based metal member 1 and the aluminum-based metal member 2 that face each other in the plate thickness direction are referred to as upper surfaces 11 and 21 and lower surfaces 12 and 22. In addition, the surface located between the edge of the upper surface 11 and the edge of the lower surface 12 of the iron-based metal member 1 is referred to as end surface 13, and the surface located between the edge of the upper surface 21 and the edge of the lower surface 22 of the aluminum-based metal member 2 is referred to as end surface 23.

[0015] In this embodiment, the joined body 100 is configured so that the aluminum-based metal member 2 overlaps the iron-based metal member 1. Specifically, the iron-based metal member 1 and the aluminum-based metal member 2 overlap with an end face 13 of the iron-based metal member 1 and an end face 23 of the aluminum-based metal member 2 misaligned. In the example shown in FIGS. 1 and 2 , the upper surface 11 of the iron-based metal member 1 and the lower surface 12 of the aluminum-based metal member 2 abut against each other so that a portion of the upper surface 11 of the iron-based metal member 1 is covered by the aluminum-based metal member 2. As a result, a step 4 is formed between the iron-based metal member 1 and the aluminum-based metal member 2.

[0016] The joined body may be configured such that the iron-based metal member 1 overlaps the aluminum-based metal member 2. In this case, the upper surface 21 of the aluminum-based metal member 2 and the lower surface 22 of the iron-based metal member 1 abut against each other so that a part of the upper surface 21 of the aluminum-based metal member 2 is covered by the iron-based metal member 1. This may form a step between the iron-based metal member 1 and the aluminum-based metal member 2, where a joint will be formed.

[0017] The joint 3A is a portion that joins the iron-based metal member 1 and the aluminum-based metal member 2, and is formed by melting the weld metal member 3 by irradiation with laser light L. In this embodiment, the joint 3A is formed in the step portion 4. Specifically, the joint 3A is formed in the step portion 4 so as to straddle the upper surface 11 of the iron-based metal member 1 and the end surface 23 of the aluminum-based metal member 2.

[0018] In this embodiment, the weld metal member 3 is a copper-based metal member made of a metal containing copper as a main component (in other words, copper or a copper alloy).

[0019] [2. Manufacturing method of bonded body] Next, a method for manufacturing the bonded body 100 will be described with reference to FIG. First, the iron-based metal member 1 and the aluminum-based metal member 2 are overlapped with each other. Specifically, the lower surface 22 of the aluminum-based metal member 2 is brought into contact with a part of the upper surface 11 of the iron-based metal member 1 so that a step portion 4 is formed.

[0020] Next, the iron-based metal member 1 and the aluminum-based metal member 2 are welded using a deposited metal member 3. Specifically, the deposited metal member 3 is irradiated with laser light L, and the molten deposited metal member 3 forms a joint 3A at the step portion 4. In this embodiment, the joint 3A is formed so as to extend along the step portion 4 by melting the weld metal member 3 while scanning the laser light L in the traveling direction shown in FIG. 2 . In this way, a joined body 100 in which the iron-based metal member 1 and the aluminum-based metal member 2 are joined together is produced.

[0021] In this embodiment, laser light L is used in combination with laser light of two different wavelength bands. Specifically, short-wavelength laser light L1 with a wavelength of 600 nm or less and near-infrared laser light L2 with a wavelength within the near-infrared region are used as the laser light L. The wavelength of the short-wavelength laser light L1 is preferably 550 nm or less. More preferably, the wavelength of the short-wavelength laser light L1 is 430 nm or more and 550 nm or less. The wavelength of the near-infrared laser light L2 is preferably 750 nm or more. More preferably, the wavelength of the near-infrared laser light L2 is 780 nm or more and 1700 nm or less. As an example, the wavelength of the near-infrared laser light L2 may be 1070 nm.

[0022] As shown in Figure 3, a diagram on the website of UW JAPAN Co., Ltd., light from a fiber laser, for example, within the wavelength band of the near-infrared laser light L2 (i.e., the near-infrared region), has a lower absorption rate in copper than in aluminum. Therefore, a large heat input is required to melt the weld metal member 3 using the near-infrared laser light L2. Therefore, when melting the weld metal member 3 using the near-infrared laser light L2, the aluminum-based metal member 2 is likely to be heated at the same time. Because aluminum has a lower melting point than copper, aluminum is likely to melt out of the aluminum-based metal member 2. Therefore, when welding the iron-based metal member 1 and the aluminum-based metal member 2, the melted aluminum and iron tend to mix to form brittle metal compounds.

[0023] Furthermore, if the absorptance of the near-infrared laser beam L2 in the weld metal members 3 is low, the heat input to the weld metal members 3 is unlikely to be stable, making it difficult to achieve a stable melted state. Thus, if the melting of the weld metal members 3 is unlikely to be stable, the size of the molten pool is likely to vary greatly. Therefore, when the near-infrared laser beam L2 is used to form the joint 3A, the melting of the weld metal members 3 is unlikely to be stable, making it difficult to achieve stable welding quality. As described above, the use of the near-infrared laser beam L2 alone to weld the iron-based metal members 1 and the aluminum-based metal members 2 is likely to cause the problems described above.

[0024] On the other hand, light from a blue laser, for example, within the wavelength band of the short-wavelength laser light L1, has a high absorptivity for copper but a low absorptivity for aluminum. Therefore, when irradiated with the short-wavelength laser light L1, the weld metal member 3 is easily heated, but the aluminum-based metal member 2 is not easily heated. In other words, when the weld metal member 3 is melted, the aluminum-based metal member 2 is not easily heated at the same time, and as a result, aluminum is not easily dissolved from the aluminum-based metal member 2. Therefore, brittle metal compounds are not easily formed during welding between the iron-based metal member 1 and the aluminum-based metal member 2.

[0025] Furthermore, when the absorptivity of the short-wavelength laser beam L1 in the weld metal members 3 is high, the heat input to the weld metal members 3 is likely to be stable, making it easier to achieve a stable melted state. In this way, when the melting of the weld metal members 3 is likely to be stable, the variation in the size of the molten pool is likely to be small. Therefore, when the short-wavelength laser beam L1 is used to form the joint 3A, the melting of the weld metal members 3 is likely to be stable, making it easier to achieve stable welding quality.

[0026] In other words, when the short wavelength laser light L1 is used to weld the iron-based metal member 1 and the aluminum-based metal member 2, it is possible to provide stable welding quality while suppressing the formation of brittle metal compounds.

[0027] Furthermore, when the near-infrared laser light L2 is used in combination with the short-wavelength laser light L1 as in this embodiment, the above-described effects of the short-wavelength laser light L1 are obtained, and the near-infrared laser light L2 also makes it easier to maintain the molten state of the molten weld metal member 3. This makes it easier for the molten weld metal member 3 to spread over the step portion 4, which tends to result in stronger joining of the iron-based metal member 1 and the aluminum-based metal member 2.

[0028] The short wavelength laser light L1 and the near infrared laser light L2 may be emitted from the same head so as to be coaxial, or may be emitted from different heads so as to be on different axes. Furthermore, the short wavelength laser light L1 and the near infrared laser light L2 may be emitted at the same timing, or may be emitted in the order of the short wavelength laser light L1 and the near infrared laser light L2 with staggered timing.

[0029] [3.Effects] According to the embodiment described above in detail, the following effects can be obtained. (3a) In this embodiment, a short-wavelength laser beam L1 is used to weld an iron-based metal member 1 and an aluminum-based metal member 2 using a weld metal member 3 that is a copper-based metal member. As described above, the short-wavelength laser beam L1 has a high absorptivity for copper but a low absorptivity for aluminum. Therefore, when the weld metal member 3 is melted by irradiation with the short-wavelength laser beam L1, the aluminum-based metal member 2 is not likely to be heated at the same time, and as a result, aluminum is not likely to melt out of the aluminum-based metal member 2. This makes it possible to suppress the formation of brittle intermetallic compounds that tend to occur when welding an iron-based metal member 1 and an aluminum-based metal member 2.

[0030] (3b) In this embodiment, a copper-based metal member is used as the weld metal member 3. As described above, the short-wavelength laser light L1 has a high absorption rate in copper, and therefore can stably melt the weld metal member 3. As a result, stable welding quality can be easily obtained.

[0031] (3c) In this embodiment, near-infrared laser light L2 is used in addition to the short-wavelength laser light L1 to weld the iron-based metal member 1 and the aluminum-based metal member 2. As a result, the short-wavelength laser light L1 melts the weld metal member 3, and the near-infrared laser light L2 tends to maintain the molten state of the weld metal member 3. This makes it easier to spread the molten weld metal member 3 over the upper surface 11 and the end surface 13 (i.e., the step portion 4), which are the joining surfaces of the iron-based metal member 1 and the aluminum-based metal member 2. This allows the iron-based metal member 1 and the aluminum-based metal member 2 to be joined more firmly.

[0032] In this embodiment, the upper surface 11 of the iron-based metal member 1 corresponds to an example of a first joining surface, and the end surface 23 of the aluminum-based metal member 2 corresponds to an example of a second joining surface.

[0033] 4. Other Embodiments Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

[0034] (4a) In the above embodiment, the weld metal member 3 is a copper-based metal member, but the metal constituting the weld metal member is not limited to copper. For example, the weld metal member may be composed of a metal primarily composed of silver (i.e., silver or a silver alloy), or a metal primarily composed of gold (i.e., gold or a gold alloy). As shown in FIG. 3, gold also has a high absorptivity of the short-wavelength laser light L1. Although not shown in FIG. 3, silver, like copper and gold, also has a high absorptivity of the short-wavelength laser light L1. Therefore, even when the weld metal member is a silver-based metal member or a gold-based metal member, the same effects as those of a copper-based metal member can be obtained.

[0035] (4b) In the above embodiment, the near-infrared laser light L2 is used in addition to the short-wavelength laser light L1 as the laser light L. However, for example, only the short-wavelength laser light L1 may be used as the laser light L.

[0036] (4c) In the above embodiment, the joined body 100 is illustrated as being manufactured by forming a joint 3A at a step 4 formed by overlapping an iron-based metal member 1 and an aluminum-based metal member 2. However, the shape of the joined body and the location where the joint is formed are not limited to this. For example, the joined body may be manufactured by abutting the iron-based metal member 1 and the aluminum-based metal member 2 at their end faces 13, 23, and forming a joint at the abutting portion so as to straddle the upper surface 11 of the iron-based metal member 1 and the upper surface 21 of the aluminum-based metal member 2. Furthermore, for example, the joined body may be manufactured by arranging the iron-based metal member and the aluminum-based metal member so that portions of their upper surfaces face each other, and forming a joint at the facing portion so as to straddle the upper surfaces.

[0037] (4d) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0038] 1...iron-based metal member, 2...aluminum-based metal member, 3...welded metal member, 3A...joint, 4...step portion, 11, 21...upper surface, 12, 22...lower surface, 13, 23...end surface, 100...joint, L...laser light, L1...short-wavelength laser light, L2...near-infrared laser light.

Claims

1. A method for manufacturing a joint formed by welding using a deposited metal member, comprising: irradiating the weld metal member with a laser beam to form a joint by the molten weld metal member, which joins the iron-based metal member and the aluminum-based metal member; the joint is formed so as to straddle a first joint surface of the iron-based metal member and a second joint surface of the aluminum-based metal member, A method for manufacturing a bonded body, wherein a short-wavelength laser beam having a wavelength of 600 nm or less is used as the laser beam.

2. A method for producing the bonded body according to claim 1, The method for manufacturing a joined body, wherein the deposited metal member is a copper-based metal member.

3. A method for producing the bonded body according to claim 1 or 2, comprising: The method for manufacturing a bonded body, wherein near-infrared laser light having a wavelength in the near-infrared region is used as the laser light in addition to the short-wavelength laser light.

Images