Dissimilar metal joint material

Abstract

To provide a dissimilar metal joint material with which a working characteristic thereafter is even, a dissimilar metal having a difference in a mechanical characteristic due to cold working.SOLUTION: Provided is a dissimilar metal joint material obtained by joining a first metal member and a second metal member. The first metal member is a recrystallized structure and the second metal member is a working structure in which recrystallization is not completed. A hardness difference between the first metal member and the second metal member is equal to or less than 30% with respect to the hardness of the first metal member. The hardness difference between the first metal member and the second metal member is small and a working characteristic thereafter becomes even.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a dissimilar metal joint in which two metal members of different types are joined to each other. Material

Background Art

[0002] When performing machining such as rolling on a dissimilar metal joint material in which two metal members of different types are joined to each other, there are many cases where differences occur in the mechanical properties of the two metals. This is because dissimilar metals have different machining characteristics and their mechanical properties after machining do not become equal. Therefore, when machining a dissimilar metal joint material, subsequent machining may not go well. For example, when rolling a dissimilar metal joint material in which two metal members are arranged and joined, the hardness difference between the two increases. When performing press working in this state, due to the hardness difference, the machining characteristics lack homogeneity, resulting in an unsatisfactory machining result.

[0003] As a prior art document regarding dissimilar metal joint materials, the applicant is aware of the following Patent Document 1.

Prior Art Document

Patent Document

[0004]

Patent Document 1

[0005] The above Patent Document 1 relates to a method for manufacturing a metal composite body and has the following description. [Page 2, right column, line 13 to line 24 of the gazette] ​Hereinafter, the details of the method for manufacturing the metal composite according to the present invention will be described. In this method, copper or a copper alloy having a recrystallization temperature lower than 260°C is prepared as a core material, and a silver-oxide dispersion alloy is prepared as a coating material. The core material is in a normal temperature state and the coating material is in a heated state, and the two are arranged in a direct face-to-face contact relationship with each other. Then, the two are rolled in one direction at least once at a speed of at least 5 m per minute and a rolling rate of 40 to 95% on the upper and lower surfaces parallel to the bonding surface of the core material and the coating material by an upper and lower movable roll with fixed side walls, so as to raise the temperature of the core material to a temperature above recrystallization, and form a metal composite with a thickness of less than 10 cm.

Disclosure of the Invention

Problems to be Solved by the Invention

[0006] However, in the above Patent Document 1, the core material and the coating material arranged in a contact relationship are joined by rolling the two. That is, dissimilar metals with different processing characteristics are joined by rolling. Therefore, the dissimilar metals after rolling still have differences in mechanical properties, and the joined material still has variations in processing characteristics. Thus, the above document does not have the technical idea of making the subsequent processing characteristics uniform for dissimilar metal joined materials with differences in mechanical properties caused by cold working, and cannot solve the above-mentioned problems.

[0007] The present invention is made for the purpose of solving the above problems. For dissimilar metal joined materials with differences in mechanical properties caused by cold working, the subsequent processing characteristics is uniformly formed dissimilar metal joining into a are provided.

Means for Solving the Problems

[0008] The claim 1 The dissimilar metal joined material described adopts the following configuration to achieve the above object. A dissimilar metal joining material formed by joining a first metal member and a second metal member, wherein the first metal member has a recrystallized structure and the second metal member has material with incomplete recrystallization a worked structure, and the hardness difference between the first metal member and the second metal member is 30% or less with respect to the hardness of the first metal member.

[0009] The dissimilar metal joining material according to claim 2 employs the following configuration. In addition to the configuration described in claim 1, The first metal member has a specific gravity of 7 or more, and the second metal member has a specific gravity of 3 or less.

[0010] 3 The dissimilar metal joining material according to claim 3 employs the following configuration. In addition to the configuration described in claim 1, The difference in electrical resistivity between the first metal member and the second metal member is within 2 times.

[0011] The dissimilar metal bonding material according to claim 4 adopts the following configuration in addition to the configuration described in claim 1. The second metal member is a metal with a lower melting point than the first metal member.

Advantages of the Invention

[0012] 1 The dissimilar metal joining material according to claim 1 is a dissimilar metal joining material formed by joining a first metal member and a second metal member. The first metal member has a recrystallized structure and the second metal member has with incomplete recrystallization a worked structure. The hardness difference between the first metal member and the second metal member is 30% or less with respect to the hardness of the first metal member. The hardness difference between the first metal member and the second metal member is small く, and the subsequent processing characteristics become uniform.

[0013] The dissimilar metal joining material according to claim 2 is such that the first metal member has a specific gravity of 7 or more and the second metal member has a specific gravity of 3 or less. The hardness difference between the first metal member and the second metal member is small く, and the subsequent processing characteristics become uniform.

[0014] Claim 3 The dissimilar metal bonding material described has a difference in electrical resistivity between the first metal member and the second metal member within 2 times. The hardness difference between the first metal member and the second metal member is small く, Subsequent processing characteristics become uniform.

[0015] In the dissimilar metal bonding material according to claim 4, the second metal member is a metal with a lower melting point than the first metal member. The hardness difference between the first metal member and the second metal member is small, and the subsequent processing characteristics become uniform.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

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Figure 4

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Figure 6

Embodiments for Carrying Out the Invention

[0017] Next, embodiments for carrying out the present invention will be described.

[0018] This embodiment is a dissimilar metal bond formed by bonding a first metal member and a second metal member that are different in type from each other material There is. First, the manufacturing method will be described. This manufacturing method Then, a bonding process, a processing process, and a heating process are performed.

[0019] 〔Bonding Process〕 The above joining process joins a first metal member and a second metal member, which are different in type from each other, to form a dissimilar metal joining material.

[0020] FIG. 1 is a diagram showing an example of the above joining process. In this example, an example of forming the dissimilar metal joining material by friction stir joining the first metal member 10 and the second metal member 20 is shown. In this example, the friction stir joining is performed by inserting a rotary tool 30 into the second metal member 20.

[0021] Also, in this example, the first metal member 10 and the second metal member 20 are each a rectangle having a longitudinal direction L and a width direction W, and the thicknesses of the first metal member 10 and the second metal member 20 are substantially equal.

[0022] In the present embodiment, the first metal member 10 and the second metal member 20 are arranged side by side in the width direction and are arranged adjacent to each other so that there is substantially no gap. For example, it is a state in which two metal members are butted against each other. In this state, the rotary tool 30 that rotates about an axis is inserted from above the surface to the side of the second metal member 20. At this time, the rotary tool 30 is inserted at a position where the outer peripheral edge of the rotary tool 30 approaches extremely close to the boundary between the first metal member 10 and the second metal member 20. That is, the outer peripheral edge of the rotary tool 30 substantially coincides with the boundary and does not contact the first metal member 10. The outer peripheral edge is the outermost rotation locus of the rotating rotary tool 30.

[0023] The insertion depth at this time is such that the lower end of the rotary tool 30 is exposed on the lower surface of the second metal member 20. That is, the rotary tool 30 is penetrated with respect to the second metal member 20.

[0024] The rotary tool 30 is inserted, for example, at one end in the longitudinal direction L, and in that state, it is moved along the boundary to the other end. As a result, plastic flow occurs in the second metal member 20, and the metal constituting the second metal member 20 and the metal constituting the first metal member are in close contact at the boundary, and the first metal member 10 and the second metal member 20 are joined.

[0025] In the figure, reference numeral 32 denotes the machining area 32 by the rotary tool 30. The machining area 32 is a band-shaped area along the locus of movement of the rotary tool 30. In the machining area 32, plastic flow occurs in the second metal member 20, and the boundary between the first metal member 10 and the second metal member 20 is joined by friction stir welding. Alternatively, the boundary between the first metal member 10 and the second metal member 20 is also joined by solid-phase diffusion.

[0026] As described above, the second metal member 20 is inserted such that the outer peripheral edge of the rotary tool 30 substantially coincides with the boundary. By doing so, plastic flow occurs only in the second metal member 20, and almost no plastic flow occurs in the first metal member 10. Therefore, a good joint with few defects such as mixing of two types of metals and voids can be obtained. Also, by inserting the rotary tool 30 only on the side of the second metal member 20, the vertical force applied to the rotary tool 30 can be greatly relaxed, preventing deterioration of the tool.

[0027] The second metal member 20 on the side where the rotary tool 30 is inserted can be made of a metal having a lower hardness than the first metal member 10. By doing so, the rotary tool 30 is inserted only into the second metal member 20 having a low viscosity during plastic flow of friction stir welding. For this reason, adhesion of metal to the rotary tool 30 is also suppressed. Therefore, the frequency of maintenance such as removing the metal adhered to the rotary tool 30 and replacing the rotary tool 30 can be reduced. Also, since the energy required to cause plastic flow is small, it is advantageous for power saving.

[0028] The second metal member 20 on the side where the rotary tool 30 is inserted can be made of a metal having a melting point lower than that of the first metal member 10. If the melting point of the second metal member 20 into which the rotary tool 30 is inserted is higher, the first metal member 10, which is the mating member, may start to melt when the temperature rises until the second metal member 20 undergoes plastic flow, resulting in poor bonding or defects. By making the second metal member 20 into which the rotary tool 30 is inserted a metal having a melting point lower than that of the first metal member 10, the occurrence of such inconveniences can be prevented.

[0029] 〔Processing step〕 The processing step cold-works the dissimilar metal joining material. By this cold working, the first metal member is made into a first processed structure, and the second metal member is made into a second processed structure.

[0030] 〔Structure after processing step〕 That is, after the processing step, the first metal member and the second metal member constituting the dissimilar metal joining material will exhibit the following structures. The first metal member becomes a first processed structure, and this first processed structure recrystallizes at the first recrystallization temperature to become a first recrystallized structure. The second metal member becomes a second processed structure. The second processed structure is a structure having a lower hardness than the first processed structure. Also, the second processed structure recrystallizes at a second recrystallization temperature higher than the first recrystallization temperature to become a second recrystallized structure.

[0031] For example, by combining copper as the first metal member 10 and aluminum as the second metal member 20, the structure after the above-described processing step can be obtained. However, the present invention is not limited to the above combination. That is, the present invention holds for various combinations of metals as long as the structure after the above-described processing step can be obtained, and is intended to include various combinations of metals. In addition, the metals constituting the first metal member 10 and the metals constituting the second metal member 20 are not limited to pure metals, but also include various alloys.

[0032] Further, as the cold working performed in the above processing step, for example, rolling can be applied. However, the cold working of the present invention is not limited to rolling, and includes processing such as forging. That is, the cold working of the present invention includes various plastic working in which the first metal member 10 and the second metal member 20 are work-hardened and have a processed structure in which recrystallization occurs by heating.

[0033] 〔Heating step〕 In the above heating step, the cold-worked dissimilar metal joining material is heated at a temperature between the first recrystallization temperature and the second recrystallization temperature. Thereby, at least the first processed structure is made into a first recrystallized structure. By doing so, the difference in mechanical properties between the first metal member and the second metal member existing in the above processing step is relaxed by the above heating step, and the subsequent processing properties become uniform.

[0034] For example, when copper is used as the first metal member 10 and aluminum is used as the second metal member 20, the first recrystallization temperature of copper is 200 to 250 ° C, and the second recrystallization temperature of aluminum is about 350 ° C. The first recrystallization temperature of the first metal member 10 (copper) is lower than the second recrystallization temperature of the second metal member 20 (aluminum).

[0035] Further, when the joining material of the first metal member 10 and the second metal member 20 is cold-worked at an equal working rate by rolling or the like, the hardness of the first processed structure in which the first metal member 10 (copper) is work-hardened is higher than that of the second processed structure in which the second metal member 20 (aluminum) is work-hardened.

[0036] Here, the recrystallization temperature refers to the heating temperature at which the strain accumulated by cold working and the work-hardened processed structure have the hardness reduced to a predetermined constant level by heating (for example, "Mechanical and Metal Materials for Young Engineers - Revised Edition -" Etsuji Yajima, Michio Ichikawa, Koichi Furuzawa, Maruzen, 1979).

[0037] By performing the above heating process, the hardness difference between the first metal member 10 and the second metal member 20 after the heating process can be made 30% or less with respect to the hardness of the first metal member 10 after the heating process.

[0038] By doing so, the hardness difference between the first metal member 10 and the second metal member 20 becomes smaller, and the subsequent processing characteristics become uniform.

[0039] For example, when copper is used as the first metal member 10 and aluminum is used as the second metal member 20, the electrical resistivity of copper is 1.68×10 -8 Ω·m and the electrical resistivity of aluminum is 2.65×10 -8 Ω·m That is, the difference in electrical resistivity between the first metal member 10 and the second metal member 20 is within 2 times. Also, the specific gravity of copper is 8.5 g / cm 3 and the specific gravity of aluminum is 2.7 g / cm 3 That is, the first metal member 10 has a specific gravity of 7 or more, and the second metal member 20 has a specific gravity of 3 or less.

[0040] Thus, when copper is used as the first metal member 10 and aluminum is used as the second metal member 20, as described above, as heating conditions for making the hardness difference between the first metal member 10 and the second metal member 20 after the heating process 30% or less with respect to the hardness of the first metal member 10 after the heating process, it can be about a heating temperature of 150°C to 300°C with heating for 1 hour. In this state, the first metal member 10 has a recrystallized structure, and the second metal member 20 has a worked structure.

[0041] Up Recorded differenceThe heat treatment method of a dissimilar metal bonding material performs a bonding process, a processing process, and a heating process. The above-mentioned bonding process bonds a first metal member and a second metal member that are different in type from each other to form a dissimilar metal bonding material. The above-mentioned processing process cold-works the dissimilar metal bonding material. By the above-mentioned cold working, the first metal member is recrystallized at the first recrystallization temperature to form a first processed structure having a first recrystallized structure. Also, the second metal member is recrystallized at a second recrystallization temperature higher than the first recrystallization temperature to form a second processed structure having a second recrystallized structure. The above-mentioned heating process heats the cold-worked dissimilar metal bonding material at a temperature between the first recrystallization temperature and the second recrystallization temperature. Thereby, at least the first processed structure is made into a first recrystallized structure. By doing so, the difference in mechanical properties between the first metal member and the second metal member existing in the above-mentioned processing process is alleviated by the above-mentioned heating process, and the subsequent processing properties become uniform.

[0042] On Recorded difference The heat treatment method of a dissimilar metal bonding material is a method for heat-treating a dissimilar metal bonding material formed by bonding a first metal member and a second metal member that are different in type from each other. The first metal member constituting the dissimilar metal bonding material exhibits a first processed structure that is recrystallized at the first recrystallization temperature to form a first recrystallized structure. The second metal member constituting the dissimilar metal bonding material exhibits a second processed structure having a lower hardness than the first processed structure, and the second processed structure is recrystallized at a second recrystallization temperature higher than the first recrystallization temperature to form a second recrystallized structure. Then, a heating process is performed in which the dissimilar metal bonding material is heated at a temperature between the first recrystallization temperature and the second recrystallization temperature. Thereby, at least the first processed structure is made into a first recrystallized structure. By doing so, the difference in mechanical properties between the first metal member and the second metal member is alleviated by the above-mentioned heating process, and the subsequent processing properties become uniform.

[0043] On Recorded differenceThe heat treatment method of the dissimilar metal joining material makes the hardness difference between the first metal member and the second metal member 30% or less with respect to the hardness of the first metal member by performing the heating step. For this reason, the hardness difference between the first metal member and the second metal member becomes small, and the subsequent processing characteristics become uniform.

[0044] above Recorded difference The heat treatment method of the dissimilar metal joining material is such that the dissimilar metal joining material is obtained by joining the first metal member and the second metal member by friction stir joining in which a rotating tool is inserted into the second metal member. Friction stir joining in which a rotating tool is inserted into the second metal member is structurally difficult to join thin plates. Therefore, in the case of thin plates, even when it is desired to select friction stir joining depending on the characteristics of the joint part, it cannot be done. By the above rolling method, it becomes possible to roll the dissimilar metal joining material to obtain a thin plate. That is, friction stir joining can be selected according to the characteristics of the joint part, and a thin plate can be obtained by subsequent rolling.

[0045] above Recorded difference The heat treatment method of the dissimilar metal joining material is such that the second metal member on the side where the rotating tool is inserted is a metal having a lower hardness than the first metal member. For this reason, adhesion of the metal to the rotating tool is also suppressed. Therefore, the frequency of maintenance such as removing the metal adhering to the rotating tool and replacing the rotating tool can be reduced. In addition, since the energy required to generate plastic flow is small, it is advantageous for power saving.

[0046] above Recorded difference The heat treatment method of the dissimilar metal joining material is such that the second metal member on the side where the rotating tool is inserted is a metal having a lower melting point than the first metal member. If the second metal member into which the rotating tool is inserted has a higher melting point, the first metal member, which is the mating material, may start to melt when it reaches a high temperature until the second metal member undergoes plastic flow, resulting in poor joining or defects. By making the second metal member into which the rotating tool is inserted a metal having a lower melting point than the first metal member, the occurrence of such inconveniences can be prevented.

[0047] The dissimilar metal joining material of the above embodiment is a dissimilar metal joining material formed by joining a first metal member and a second metal member. The first metal member has a recrystallized structure, and the second metal member has a worked structure. The hardness difference between the first metal member and the second metal member is 30% or less with respect to the hardness of the first metal member. For this reason, the hardness difference between the first metal member and the second metal member becomes small, and the subsequent processing characteristics become uniform.

[0048] The dissimilar metal joining material of the above embodiment is a dissimilar metal joining material formed by joining a first metal member and a second metal member. The first metal member has a specific gravity of 7 or more, and the second metal member has a specific gravity of 3 or less. The hardness difference between the first metal member and the second metal member is 30% or less with respect to the hardness of the first metal member. For this reason, the hardness difference between the first metal member and the second metal member becomes small, and the subsequent processing characteristics become uniform.

[0049] The dissimilar metal joining material of the above embodiment is a dissimilar metal joining material formed by joining a first metal member and a second metal member. The difference in electrical resistivity between the first metal member and the second metal member is within 2 times. The hardness difference between the first metal member and the second metal member is 30% or less with respect to the hardness of the first metal member. For this reason, the hardness difference between the first metal member and the second metal member becomes small, and the subsequent processing characteristics become uniform.

Example

[0050] Next, examples will be described.

[0051] A copper plate was used as the first metal member 10, and an aluminum plate was prepared as the second metal member 20. The copper plate and the aluminum plate were joined by the friction stir welding method shown in FIG. 1 (joining step) to obtain a dissimilar metal joining material.

[0052] Figure 2 is a cross-sectional hardness distribution diagram of the dissimilar metal joint material obtained as described above. The center is the joint interface, the horizontal axis is the distance from the joint interface, and the vertical axis is the micro-Vickers hardness (the same applies in Figures 3 to 5). It can be seen that the first metal member 10 (copper plate) has a higher hardness than the second metal member 20 (aluminum plate).

[0053] Figure 3 is a cross-sectional hardness distribution diagram of the above dissimilar metal joint material after roll rolling (processing step) to obtain a rolled material. The rolling process was carried out by repeating the passes a plurality of times until the final rolling ratio reached 91%. It can be seen that both the first metal member 10 (copper plate) and the second metal member 20 (aluminum plate) have increased in hardness due to work hardening compared to the state after joining shown in Figure 2.

[0054] Figure 4 is a cross-sectional hardness distribution diagram of the above rolled material after annealing (heating step) at 150°C. The annealing time is 1 hour. It can be seen that the hardness of the first metal member 10 (copper plate) has decreased significantly and it has recrystallized. The second metal member 20 (aluminum plate) shows almost the same hardness as the state after rolling shown in Figure 3. Also, it can be seen that due to the above annealing, the hardness difference between the first metal member 10 (copper plate) and the second metal member 20 (aluminum plate) has become 30% or less of the hardness of the first metal member with respect to the hardness difference between the first metal member and the second metal member.

[0055] Figure 5 is a cross-sectional hardness distribution diagram of the above rolled material after annealing (heating step) at 200°C. The annealing time is 1 hour. It can be seen that the hardness of the first metal member 10 (copper plate) has decreased significantly and it has recrystallized. The second metal member 20 (aluminum plate) shows almost the same hardness as the state after rolling shown in Figure 3. Also, it can be seen that due to the above annealing, the hardness difference between the first metal member 10 (copper plate) and the second metal member 20 (aluminum plate) has become 30% or less of the hardness of the first metal member with respect to the hardness difference between the first metal member and the second metal member.

[0056] Figure 6 is a diagram showing the change in hardness when the rolled material is annealed at different heating temperatures. The annealing time is 1 hour. It can be seen that the first metal member 10 (copper plate) becomes a recrystallized structure at about 150°C and its hardness decreases. The second metal member 20 (aluminum plate) starts to recrystallize at about 250 - 300°C and its hardness decreases. Therefore, within the range of the heating temperature from 150°C to 250°C, the hardness difference between the first metal member 10 (copper plate) and the second metal member 20 (aluminum plate) can be made 30% or less with respect to the hardness of the first metal member.

[0057] Table 1 below shows the relationship between the heating temperature and the hardness when the rolled material is annealed.

Table 1

[0058] When copper is used as the first metal member 10 and aluminum is used as the second metal member 20, by setting the heating temperature to about 150°C to 300°C for 1 hour of heating, it can be seen that the hardness difference between the first metal member 10 and the second metal member 20 after the heating process can be made 30% or less with respect to the hardness of the first metal member 10 after the heating process.

[0059] 〔Modification Example〕 The above has described particularly preferred embodiments of the present invention. However, the present invention is not intended to be limited to the illustrated embodiments, and can be implemented in various modified forms, and the present invention is intended to include various modification examples.

[0060] For example, in the above Explanation , the friction stir welding method was applied as a method for forming the joint portion, but it is not limited thereto, and various joint methods can be applied.

Explanation of Reference Numerals

[0061] 10: First metal member 20: Second metal member 30: Rotary tool 32: Machining area

Claims

1. A dissimilar metal joining material formed by joining a first metal member and a second metal member, wherein the first metal member has a recrystallized structure, the second metal member has a worked structure in which recrystallization is not complete, and the hardness difference between the first metal member and the second metal member is 30% or less with respect to the hardness of the first metal member A dissimilar metal joining material characterized by this.

2. wherein the first metal member has a specific gravity of 7 or more, and the second metal member has a specific gravity of 3 or less The dissimilar metal joining material according to Claim 1.

3. wherein the difference in electrical resistivity between the first metal member and the second metal member is within 2 times The dissimilar metal joining material according to Claim 1.

4. The second metal member is a metal having a melting point lower than that of the first metal member The dissimilar metal joining material according to Claim 1.

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